Method for guiding a moulding material in a moulding material cycle comprising two or more cycles

Abstract

The invention relates to a method for guiding a moulding material in a moulding material cycle comprising two or more cycles.

Description

[0001] HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Wiesenstraße 23, 40549 Düsseldorf Method for guiding a molding material in a molding material cycle comprising two or more cycles The present invention relates to a method for guiding a molding material in a molding material cycle comprising two or more cycles. Clays used to bind molding materials typically contain smectites. Examples of such smectite-containing clays are bentonites, in particular sodium and calcium bentonites, which contain sodium and calcium respectively, in addition to the elements magnesium, aluminum, and silicon. Other smectite-containing clays are hectorite, saponite, nontronite, beidellite, or sauconite. Clays such as kaolinite or illite can be used as clay-containing binders in mixtures with smectite-containing clays.The smectite-containing clay preferably has a montmorillonite content of 50 wt% or more, particularly preferably 60 wt% or more, particularly preferably 70 wt% or more. If the montmorillonite content in a naturally occurring smectite-containing clay is too low, it can be increased by purification. This applies in particular to bentonite. For example, sodium bentonite can contain 70 to 95 wt% montmorillonite, with quartz, opal, cristoballite, feldspar, biotite, clinoptilite, calcite, gypsum, and others occurring as the remaining components. ^ *20^23^93^82^14^* ^^^^^^^ Accordingly, in this document, the terms “smectite-containing clays” and “bentonite” are used both for corresponding clays extracted from natural deposits and for those produced by purifying naturally occurring clays.In this document, the term "clay-bound mold" is used, where appropriate, to refer to casting molds bound with a smectite-containing clay. This always refers to casting molds bound with a smectite-containing clay. Smectite-containing clays in the form of sodium or calcium bentonite and / or mixtures thereof are preferred in the foundry industry. These mixtures are sometimes created in situ by the addition of salts and the resulting ion exchange. Any sand that can form a foundry mold and retain this shape at high temperatures and in contact with hot metal can be used as a mold base material. Typical sands are silica sand, olivine sand, chromium ore sand, zircon sand, as well as artificially produced ceramic sands or mixtures of these sands. Typically, a mold contains at least 40% sand, preferably over 50% sand, particularly preferably over 60% sand, and most preferably over 70% sand.In industrial practice, clay-bonded casting molds are generally made from a molding material that contains smectite-containing clay as a binder and the mold base material, as well as additives and water. Such molding materials are also referred to as "green sand" or "wet casting sand." Compaction of the molding material solidifies it, thus ensuring sufficient dimensional stability. A molding material with smectite-containing clay as a binder is typically used in industrial practice in a molding material cycle. Molding material cycle, as defined in this disclosure, means that molding material from cast molds ("cast molding material," also referred to as used sand) is processed and used to produce new molding material, from which molds are again produced and cast.The mold base material contained in the molding material is therefore at least partially present as a component of processed molding material from at least one previously cast clay-bonded mold. A molding material cycle within the meaning of the present disclosure consists of at least two chronologically successive cycles. Two (not necessarily directly consecutive) cycles of a molding material cycle can therefore be distinguished as an earlier cycle and a later cycle. If the molding material cycle consists of only two cycles, then the first cycle in the chronological sequence is the earlier cycle, and the second cycle in the chronological sequence is the later cycle. A cycle of this molding material cycle can be described by the following characteristic steps (see Figure 1 for the following designation of the steps): (Step 1) Production of the molding material, i.e.Producing a molding material comprising recycled molding material from a previous cycle and additives (see below) (Step 2) Making the mold, i.e. making a mold bound with smectite-containing clay from the molding material produced in step (1), (Step 3) Casting, i.e. producing a casting by casting the mold produced in step (2) (Step 4) Separating, i.e. separating the casting produced in step (3) from the mold, resulting in a cast molding material comprising material from the cast mold (Step 5) Processing the cast molding material, i.e. processing the cast molding material from step (4) so ​​that a first processed molding material is obtained for producing a new molding material in step (1) of a later cycle. In certain cases, it is preferred that one, several or all cycles of the molding material cycle comprise further steps and / or that individual steps of said steps have further features.Details can be found in the following description as well as the appended claims and drawings. In each cycle of the molding material cycle described above, in step (3) a casting is produced by pouring the mold produced in step (2). The molding material undergoes significant material changes due to thermal and chemical stress during pouring (step (3) of the cycle). To enable a recycling of the molding material, the poured molding material must be processed. In some cases, particularly for the production of castings with complex geometries, in step (3) a casting is produced by pouring the mold produced in step (2) with one or more inserted cores (see Figure 3). Cores that are inserted into clay-bonded molds are typically not clay-bonded. Typically, such cores are bonded with an organic binder, e.g.a polyurethane or a phenolic resin, or with an inorganic binder containing no clay, e.g., a binder containing water glass. If the casting produced in step (3) is separated from the mold and cores in step (4), the result is usually a cast molding material containing material from the cast cores (used core sand). The processing of the cast molding material in step (5) leads to a processed molding material that remains in the molding material cycle. Thus, a portion of the molding base material used (usually quartz sand) remains in the molding material cycle as a component of the processed cast molding material. The processing regularly includes crushing the cast molding material (grain separation) and extensive removal of metal residues and other contaminants, for example contaminants in the form of auxiliary products from the casting process (core marks, feeder residues, etc.).The thermal, mechanical, and possibly chemical stresses during casting produce wear products such as fine sand particles, inactive clay particles, decomposition products of the additives, particularly the lustrous carbon formers, reaction products of core binders, and oolitized grains of the mold base material. To prevent such wear products from accumulating in the mold material cycle and / or to negatively impact the mold material properties or to prevent the required active proportions of the binder (smectite-containing clay) and the additives from decreasing too much, additives are added in step (1) of each subsequent cycle during mold material production, i.e. the processed mold material is refreshed with the additives. To keep the mass of the mold material in the cycle constant, a corresponding amount of mold material is removed from the mold material cycle.This can take place before rejuvenation by the aggregates (i.e. in step (5)) or after rejuvenation by the aggregates. The aggregates typically comprise smectite-containing clay, water, additives (see below) and one or more raw materials from the group consisting of - fresh molding material (new sand), - second processed molding material produced by processing uncast molds and / or cores and / or parts thereof - third processed molding material produced by processing molds and / or cores and / or parts thereof that were manufactured and cast outside the molding material cycle under consideration. Preferably, the aggregates (in particular the bentonite) also comprise water. The molds and cores from which the second and third processed molding materials are obtained as defined above do not have to be clay-bound.In particular, the cores are typically not clay-bound, but manufactured with a conventional organic binder, e.g. polyurethane, particularly polyurethane formed in the cold box process, or with a phenolic resin in the form of a resole, particularly those resoles used in the hot box or warm box process, or a novolak, particularly novolaks used in the croning process or shell molding process. In each cycle of an industrial molding material cycle, an essentially consistent quality of the castings should be achieved during casting. By controlled supply and removal of components of the molding material, essentially constant, optimal molding material properties can be achieved in the molding material cycle (molding material conditioning). In this process, the molding material is treated in each cycle by determining the required addition of smectite-containing clay (addition optional), additives, water and new sand orThe molding material is conditioned, i.e., optimally adjusted, by a second and third prepared molding material as defined above, as well as by determining the amount of used sand to be removed and by specifying machine parameters such as mixing time or cooling intensity. In industrial practice, molding materials for the production of clay-bonded casting molds usually contain additives in the form of so-called lustrous carbon formers. Lustrous carbon formers (also known as lustrous carbon carriers, see https: / / www.giesserei-praxis.de / giesserei-lexikon / glossar / glanzkohlenstoff) are molding material additives capable of forming hydrocarbon-containing gases that are coked in the reducing atmosphere of the mold cavity during casting. This produces lustrous carbon. Commonly used lustrous carbon formers include hard coal dust, pitch, bitumen, resins, oils, plastics, and mixtures thereof.Lustrous carbon formers are particularly added to clay-bonded mold materials for iron casting. The lustrous carbon prevents wetting by the liquid casting material at the metal / mold interface. Lustrous carbon formers in the mold material can also buffer quartz expansion and prevent sand expansion defects. However, increasing proportions of hard coal dust or other lustrous carbon formers and higher proportions of the decomposition products (coke) of the lustrous carbon formers in the processed mold material increase the water requirement of the mold material. An increased amount of water in the mold material can lead to casting defects such as explosion penetrations. Since lustrous carbon formers are thermally decomposed and coked during casting, the corresponding losses in the mold material cycle must be regularly replaced in industrial practice by adding fresh lustrous carbon formers.For this purpose, lustrous carbon formers are freshly added to at least some cycles, preferably all cycles, of the molding material cycle. A significant disadvantage of using lustrous carbon formers is the release of emissions, for example, in the form of CO, CO2, and NO. xand volatile organic compounds, particularly aromatic hydrocarbons such as benzene, toluene, and xylenes ("BTX emissions"), but also polycyclic aromatics. In addition, volatile sulfur-containing compounds are also usually emitted, since lustrous carbon formers often contain sulfur and / or sulfur-containing impurities. A further problem is the considerable risk of dust explosions and spontaneous combustion when handling lustrous carbon formers. Therefore, in industrial foundries, lustrous carbon formers are typically used in the form of a pre-mixed mixture with the smectite-containing clay, especially bentonite, in the production of clay-bonded molds. For the reasons stated, it is desirable and necessary to limit the use of lustrous carbon formers or to replace them with suitable alternatives, at least in a significant proportion. US 5,372,636 A discloses a molding material comprising sand, a sodium smectite clay (in particular sodium bentonite) and at least one oxide, salt (in particular carbonate) or hydroxide of a metal, e.g. aluminum, calcium, iron, sodium, magnesium, boron or zinc. Recycling of the molding material is not disclosed. Thus, this document provides no information as to whether such molding materials are suitable for use in a molding material cycle. WO 03 / 066253 A1 describes a method for producing a molding material, in particular a recycled one, for foundry purposes, according to which a material which does not swell in water is added to a mixture of a granular mass and additives, such as a binder, e.g. bentonite, and water. As non-swellable porous materials, framework or tectosilicates, such as zeolites, pumice or pumice stones, allophane, imogolite, diatomaceous earth, polygarskite, sepiolite, diatomaceous earth,or (acid and / or heat-treated) clays are used. CN 108356214 discloses molding material mixtures comprising sand, water, bentonite, and an additive with the following composition: SiO2 50-85 wt% Al2O3 9-45 wt% MgO 0.2-3 wt% Fe2O3 1-8 wt% CaO 1-7 wt% Fe3O4 0.4-8 wt% The additive is produced by mixing the individual oxides. It is intended to replace lustrous carbon formers. Molding materials containing this additive are said to be easily recyclable. Exemplary molding materials were used for two to four months. The primary object of the present invention is to reduce carbon-based emissions and / or carbon-based casting defects. Carbon-based emissions include, for example, emissions in the form of CO, CO2, and volatile organic compounds, in particular aromatic hydrocarbons such as benzene, toluene and xylenes (“BTX emissions”).but also polycyclic aromatics. This object is achieved by a method for guiding a molding material in a molding material cycle comprising two or more cycles, comprising the following steps: - in an earlier cycle of said two or more cycles of the molding material cycle, pouring into a mold comprising molding material bound with smectite-containing clay, resulting in a cast molding material, - processing the cast molding material to produce a first processed molding material, - in a later cycle of said two or more cycles of the molding material cycle, producing a molding material comprising (i) a first processed molding material, and (ii) additives comprising - one or more raw materials from the group consisting of - mold base material, - a second processed molding material produced by processing molding material from uncast molds and / or cores and / or parts thereof,- a third processed molding material produced by processing molding material from molds and / or cores cast outside the molding material cycle and / or parts thereof, - an additive containing at least one dehydratable inorganic compound that releases water at a temperature of 150 °C or more, - and optionally smectite-containing clay, preferably bentonite, wherein at least one of the processed molding materials contains an inorganic binder and / or reaction products thereof. The inorganic binder preferably contains water glass. The additives preferably also comprise water. The processed molding materials preferably contain no organic binders.Particularly preferably, no organic material at all. The processed molding materials most preferably contain no carbon and no carbon carrier. The carbon content of a molding material is determined by elemental analysis and includes carbon components from organic carbon carriers as well as from inorganic carbon carriers. Organic carbon carriers are, in particular, lustrous carbon formers, organic binders, organic additives, as well as residues or decomposition products of lustrous carbon formers, organic binders, and organic additives. Inorganic carbon carriers are, in particular, carbonates, which may be contained in the molding material as an additive. In molding materials with smectite-containing clay as a binder, the carbon content can be reduced, in particular, bythat the use of lustrous carbon formers is reduced or avoided. By reducing or even avoiding the use of lustrous carbon formers, fossil resources are conserved. Thus, a further object solved by the present invention is to provide a resource-saving molding material cycle. By reducing or even avoiding the use of lustrous carbon formers, the risk of dust explosions and spontaneous combustion during transport, storage, and handling of the lustrous carbon formers is reduced or even eliminated. Thus, a further object solved by the present invention is to reduce the risk of dust explosions and spontaneous combustion during transport,the storage and handling of lustrous carbon formers. By reducing or even avoiding the use of lustrous carbon formers, fewer pyrolysis products are formed during casting, which contaminate the cast molding material or the molding material discharged from the molding material cycle. The lower carbon and sulfur contents in the cast molding material associated with a reduction in the use of lustrous carbon formers are also advantageous for the landfilling of non-reusable molding material components. Thus, a further object solved by the present invention is to facilitate the reuse or landfilling of cast molding material. Further objects solved by the present inventionconsist in reducing sulfur-based emissions and NOx emissions during a molding material cycle comprising two or more cycles. A further object solved by the present invention is to reduce the odor nuisance released during casting. The reduction in the proportion of lustrous carbon should not impair the properties of the molding material, the casting molds produced therefrom, and the castings produced therewith in an unacceptable manner. The molding material cycle to which the method according to the invention relates is preferably an industrial molding material cycle in a foundry, preferably a foundry with at least one production line integrated into the molding material cycle, and optionally at least one further production line in which molds and / or cores are produced and / or cast that are not clay-bound. It is not absolutely necessarythat the above-defined additive is added in each cycle of the molding material cycle. A molding material cycle according to the invention can comprise individual cycles in which this additive is not added. Further special features, details, advantages, and preferred embodiments of the process according to the invention emerge from the following description as well as the appended claims and drawings. The solution to the above-defined objects is based on the use of an additive that is similarly effective in preventing mold expansion defects, in separating metal from molding material, and in promoting mold decomposition as the lustrous carbon formers used in the prior art. Surprisingly, it has been found that dehydratable inorganic compounds that release water at a temperature of 150°C or more,in preventing mold expansion defects and in promoting mold decomposition, they can be similarly effective as the lustrous carbon formers used in the prior art. Dehydration means the elimination of chemically (e.g., in the form of hydroxide ions) or physically (e.g., as water of crystallization in hydrates) bound water by heating. The dehydratable inorganic compounds contained in the additive to be used according to the invention are preferably compounds from the group of hydroxides and hydrate salts of metals. The term hydroxides as used here also includes oxide hydroxides. Hydroxides and hydrate salts of metals in the +II or +III oxidation state are preferred, particularly hydroxides of metals in the +II or +III oxidation state. Special preference is given to magnesium hydroxide (especially in the form of brucite) and aluminum hydroxide.Most preferred is aluminum trihydroxide Al(OH)3. The aluminum trioxide can be present in various modifications, particularly as gibbsite, bayerite, or nordstrandite, as well as in minerals in combination with other hydroxides or oxides. The additive preferably contains one or both compounds from the group consisting of aluminum hydroxide and magnesium hydroxide. The proportion of aluminum hydroxide is preferably at least 80%, more preferably at least 90%, particularly preferably at least 95%, and especially preferably at least 99%, based on the total mass of aluminum hydroxide and magnesium hydroxide in the additive. The additive to be used according to the invention preferably comprises no carbon or carbon carriers. In the process according to the invention, in an earlier cycle of the two or more cycles of the molding material cycle, a mold comprising molding material bound with smectite-containing clay is cast.whereby a casting is produced. A cast molding material results from the pouring of the mold. The cast molding material is processed in the manner described above, resulting in a first processed molding material. In order to keep the mass of the circulated molding material constant, a portion of the cast molding material is optionally discharged during processing, resulting in discharged molding material. However, it is not absolutely necessary that processed molding material be discharged in every cycle of the molding material cycle. A molding material cycle according to the invention can comprise individual cycles in which no discharge of processed molding material occurs. In a later cycle of the molding material cycle, a molding material is produced comprising (i) first processed molding material as defined above,and (ii) additives. These additives comprise - the additive as defined above - and one or more raw materials from the group consisting of - mold base material, in particular quartz sand - a second processed mold material produced by processing mold material from uncast molds and / or cores and / or parts thereof, - a third processed mold material produced by processing mold material from molds and / or cores and / or parts thereof cast outside the mold material cycle, - and optionally smectite-containing clay, preferably bentonite. If a portion of the cast mold material has not already been discharged after processing, a portion of the produced mold material can now be discharged in order to keep the mass of the circulated mold material constant, resulting in discharged mold material. However, this is not mandatory. A mold material cycle according to the invention can comprise individual cycles,in which no molding material is discharged. At least one of the prepared molding materials used in the process according to the invention (second and third prepared molding material as defined above) comprises an inorganic binder and / or reaction products thereof. The inorganic binder preferably contains water glass, in particular water glass hardened thermally or by gassing with CO2. Cast cores or molds contain reaction products of the inorganic binder formed during casting. The molding material produced in a later cycle of the molding material cycle comprises one, several, or all of the above-mentioned raw materials. The molding base material used as raw material preferably comprises fresh quartz sand (new sand) or silica sand, olivine sand, chromium ore sand, zircon sand, or artificially produced ceramic sands or mixtures of these sands. The smectite-containing clay is preferably bentonite,in particular from the group consisting of sodium and calcium bentonite and mixtures thereof. The second reprocessed molding material as defined above is produced by reprocessing molding material from uncast molds and / or cores and / or parts thereof. The uncast molds and / or cores are molds and / or cores that were not cast for various reasons, e.g. due to processing errors or lack of dimensional accuracy. The third reprocessed molding material as defined above is produced by reprocessing molding material from molds and / or cores and / or parts thereof cast outside the considered molding material cycle, i.e. molds and cores that were cast, for example, in another production line. Reprocessed molding material containing material from cast or uncast molds and / or cores and / or parts thereof,wherein the molds and / or cores are produced with an organic binder, is preferably not used. The molding material produced in the later cycle preferably has one or more of the following parameters: - a concentration of less than 1.5%, preferably less than 0.8% carbon, based on the mass of the molding material, determined by elemental analysis - a concentration of less than 0.1%, preferably less than 0.05% nitrogen, based on the mass of the molding material, determined by elemental analysis - a concentration of less than 0.05%, preferably less than 0.03% sulfur, based on the mass of the molding material, determined by elemental analysis - a loss on ignition of at most 5%, preferably at most 3.5%, determined according to VDG Data Sheet P33 (April 1997). The molding material produced in the later cycle particularly preferably has one or more of the following parameters: - a concentration of less than 0.8%, preferably less than 0.4%,particularly preferably less than 0.2% carbon based on the mass of the molding material, determined by elemental analysis - a concentration of less than 0.05%, preferably less than 0.03%, very particularly preferably less than 0.01% nitrogen, based on the mass of the molding material, determined by elemental analysis - a concentration of less than 0.03%, preferably less than 0.01%, very particularly preferably less than 0.005% sulfur, based on the mass of the molding material, determined by elemental analysis - a loss on ignition of at most 3.5%, preferably at most 3%, very preferably at most 2.5%, determined according to VDG Data Sheet P33 (April 1997). All of the stated parameters of the molding material are preferably in the above-mentioned preferred, in particular in the above-mentioned particularly preferred ranges. In one embodiment of the method according to the invention, in the earlier cycle, casting takes place in a mold with at least one inserted core,which was produced with an inorganic binder. This results in a cast molding material that comprises material from the cast mold and material from the cast core. The material from the cast core comprises reaction products of the inorganic binder formed during casting. Cores used in clay-bonded molds are typically not clay-bonded. In the embodiment of the method according to the invention described here, these cores are produced with an inorganic binder. The inorganic binder preferably contains water glass, in particular water glass hardened thermally and / or by gassing with CO2. The cast molding material resulting from the earlier cycle of the molding material cycle, and the resulting first processed molding material, thus contains material from at least one cast mold and at least one cast core.which were cast in the same casting process. In this embodiment of the method according to the invention, a second processed molding material can be used which contains material from uncast molds and / or cores and / or parts thereof, wherein the molds and / or cores are preferably produced with an inorganic binder, e.g. a binder containing water glass, and / or a third processed molding material which contains material from cast molds and / or cores and / or parts thereof, wherein the molds and / or cores are preferably produced with an inorganic binder, e.g. a binder containing water glass. Processed molding material which contains material from cast or uncast molds and / or cores and / or parts thereof, wherein the molds and / or cores are produced with an organic binder, e.g. phenolic resin or polyurethane,is preferably not used. In another embodiment of the method according to the invention, casting takes place in the earlier cycle in a mold without an inserted core, so that the first prepared molding material does not contain any material from cast cores. In this embodiment of the method according to the invention, the second prepared molding material contains material from uncast cores and / or molds and / or parts thereof, wherein the molds and / or cores were produced with an inorganic binder, and / or the third prepared molding material contains material from cast molds and / or cores and / or parts thereof, wherein the molds and / or cores were produced with an inorganic binder. The inorganic binder preferably contains water glass,in particular, water glass hardened thermally and / or by gassing with CO2. Material from cast molds and cores comprises reaction products of the inorganic binder formed during casting. Reprocessed molding material containing material from cast or uncast molds and / or cores and / or parts thereof, wherein the molds and / or cores are produced with an organic binder, e.g., phenolic resin or polyurethane, is preferably not used. In the process according to the invention, the circulated molding material is preferably used to produce molds for iron casting. In the process according to the invention, an earlier and a later, and preferably all cycles of the process according to the invention preferably comprise the following steps (cf. Figure 2, the further features of which are not intended to be limiting): (Step 1) Production of the molding material,i.e., producing a molding material comprising (i) the first processed molding material produced by processing the cast molding material resulting from a previous cycle of the molding material cycle, as defined above, and (ii) additives as defined above. (Step 2) Mold production, i.e., producing a mold bonded with smectite-containing clay from the molding material produced in step (1). (Step 3) Casting, i.e., producing a casting by casting the mold produced in step (2). (Step 4) Separation, i.e., separating the casting produced in step (3) from the mold, resulting in a cast molding material. Step (5) Processing the cast molding material, i.e., processing the cast molding material from step (4) to obtain a first processed molding material for producing a new molding material in step (1) of a later cycle, and if necessary, removing part of the cast molding material,so that discharged molding material results. If a portion of the cast molding material was not already discharged during processing in step (5), a portion of the molding material produced in step (1) of the next cycle is discharged in order to keep the mass of the circulated molding material constant, so that discharged molding material results. In a specific embodiment of the method according to the invention, an earlier and a later, and preferably all cycles of the method according to the invention preferably comprise the following steps (cf. Figure 4, the further features of which are not intended to be limiting): (Step 1) Production of the molding material, i.e. production of a molding material comprising (i) processed molding material produced by processing the cast molding material resulting from an earlier cycle of the molding material cycle, as defined above, and (ii) additives as defined above (Step 1a) Production of the core molding material,i.e. producing or providing a molding material for producing at least one core, wherein the molding material contains an inorganic binder, preferably a binder containing water glass (Step 2) Producing the mold, i.e. producing a mold bound with smectite-containing clay from the molding material produced in step (1) (Step 2a) Producing the core, i.e. producing at least one core and inserting the at least one core into the mold produced in step (2) (Step 3) Casting, i.e. producing a casting by casting the mold produced in step (2) with the at least one core inserted in step (2a), (Step 4) Separating, i.e. separating the casting produced in step (3) from the mold and the at least one core, wherein a cast molding material containing material from the cast mold and from the cast core results (Step 5) Processing, i.e. Preparation of the cast molding material from step (4),so that a first prepared molding material is obtained for producing a new molding material in step (1) of a later cycle, and optionally discharging a portion of the cast molding material, resulting in discharged molding material. If a portion of the cast molding material was not already discharged during processing in step (5), a portion of the molding material produced in step (1) of the next cycle is discharged in order to keep the mass of the circulated molding material constant, resulting in discharged molding material. In certain cases, it is preferred that one, several, or all cycles of the molding material cycle include further steps, and / or that individual steps have further features. Details can be found in the following description as well as the appended claims and drawings. During the production of the molding material, in particular in step (1) of the molding material cycle,Preferably, the prepared molding material and the additives are mixed. The additives preferably also include water. Preferably, the mold with the casting and - if present - the at least one core is cooled before separation in step (4). Preferably, the cast molding material is cooled before processing. The processing usually includes extensive removal of metal residues and other contaminants, for example, contaminants from auxiliary products from the casting process (core marks, feeder residues, etc.) and comminution of the cast molding material (grain separation). The thermal, mechanical, and possibly chemical stress results in wear products such as fine sand particles, inactive clay particles, decomposition products of the additives and / or the lustrous carbon formers, or reaction products of core binders.as well as oolite grains of the mold base material. To prevent such wear products from accumulating in the mold material cycle, and / or to prevent the mold material properties from being negatively affected, and / or to prevent the required active components of the binder (smectite-containing clay) and the additive used according to the invention from decreasing too much, additives are added to the mold material in a subsequent cycle, particularly in step (1), during the production of the mold material. This means that the prepared mold material is refreshed by the additives. To keep the mass of the mold material circulated constant, a corresponding amount of mold material is removed from the mold material cycle. This can occur before refreshing with the additives (i.e., particularly in step (5)), or after refreshing with the additives.i.e. after the production of the molding material in the later cycle. In the latter case, the amount of additives added is kept as low as possible. In some cases, step (5) therefore comprises the necessary discharge of cast molding material in the same amount as in step (1) of the next cycle, which is refreshed with additives comprising the additive to be used according to the invention; in this way, it is possible to achieve a uniform property profile. Preferably, in step (5), 0.5 wt% to 20 wt%, preferably 2 wt% to 15 wt%, particularly preferably 5 wt% to 10 wt% of the cast molding material is discharged (sand discharge) and in step (1) of the following cycle, a corresponding amount of additives is added in order to keep the mass of the molding material circulated in the circuit constant. If in step (5) a part of the cast molding material has not already been discharged, in order to keep the mass of the molding material in the circuit constant, 0,5 wt% to 20 wt%, preferably 2 wt% to 15 wt%, particularly preferably 5 wt% to 10 wt% of the molding material produced in step (1) is discharged. The molding material discharged during processing in step (5) preferably meets the requirements of landfill class DK I according to Annex 3 of the Ordinance on Landfills and Long-Term Storage (Deponieverordnung-DepV) of April 27, 2009. The molding material cycle to which the process according to the invention relates preferably comprises at least 10 cycles, preferably at least 15 cycles, particularly preferably at least 30 cycles. The additive to be used according to the invention (as defined above) is preferably free-flowing and / or pourable. The additive is preferably in the form of a powder or granulate. The additive is particularly preferably in the form of particles with a grain size of 20 µm to 200 µm, determined by laser granulometry. The proportion of dehydratable inorganic compounds is preferablywhich release water at a temperature of 150°C or more, 1% to 100%, based on the total mass of the additive as defined above. More preferably, the proportion of dehydratable inorganic compounds which release water at a temperature of 150°C or more is 20% to 100%, based on the total mass of the additive as defined above. Most preferably, the proportion of dehydratable inorganic compounds which release water at a temperature of 150°C or more is 30% to 100%, based on the total mass of the additive as defined above. Most preferably, the proportion of dehydratable inorganic compounds which release water at a temperature of 150°C or more is 50% to 100%, based on the total mass of the additive as defined above. The additive preferably contains aluminum hydroxide, wherein the aluminum hydroxide contained in the additive has a water content in the range of 0.01% to 20%, preferably 0.01% to 12%. Particularly preferred are aluminum hydroxides with a water content of less than 1% (i.e., less than 1% water content), determined by thermogravimetric analysis in the temperature range up to 105°C. No special effort is required for drying the aluminum hydroxide. The additive may contain aluminum hydroxide mixed with iron oxide and / or iron hydroxide, with the proportion of aluminum hydroxide being greater than 40%, based on the total mass of aluminum hydroxide, iron oxide, and / or iron hydroxide. The additive to be used according to the invention preferably has a pH in the range of 7 to 14, determined according to DIN 19747:2009-07 (sample preparation), DIN EN 12457-1:2003-01 (leaching), and DIN EN ISO 10523:2012-04 (determination of the pH value). The additive to be used according to the invention preferably contains one or more dehydratable inorganic compounds,which release water in a temperature range of 150°C to 850°C. The total proportion of elements from the group consisting of Pb, Cd, Cr, Co, Cu, Mo, Ni, Hg, Se, Zn, P, As, F, Br, and Cl is preferably 1% by weight or less, preferably 0.5% by weight or less, particularly preferably 0.1% by weight, and most particularly preferably 0.05% by weight, based on the total mass of the additive. When producing the molding material, the order in which the individual components are combined is flexible. For example, the additives can be provided as a mixture. Alternatively, the additive and smectite-containing clay can be provided as a mixture.and the other additives separately. This procedure corresponds to the currently common provision of lustrous carbon formers in a prefabricated mixture with smectite-containing clays. Thus, existing storage and dosing facilities in the foundry can continue to be used. Alternatively, the additive can be provided separately from the other additives. Alternatively, the additive and optionally the smectite-containing clay, or a premix of additive and smectite-containing clay, can first be mixed with the first prepared molding material, and then further raw materials are added as described above. The total mass of the raw materials is preferably from the group consisting of - basic molding material, - second prepared molding material produced by preparing molding material from uncast molds and / or cores and / or parts thereof,- third processed molding material produced by processing molds and / or cores and / or parts thereof cast outside the molding material cycle: 0.5 to 10 wt.%, preferably 1 to 8 wt.%, particularly preferably 1.5 to 7 wt.%, based on the total mass of the molding material to be produced. The mass of the smectite-containing clay added as an aggregate is preferably 0.1 to 1.5 wt.%, more preferably 0.3 to 1.2 wt.%, particularly preferably 0.5 to 1.0 wt.%, based on the total mass of the molding material to be produced. The total mass of the dehydratable inorganic compounds added as an aggregate with the additive (as defined above) that release water at a temperature of 150°C or more is 0.1 to 1 wt.%, preferably 0.3 to 0.8 wt.%, particularly preferably 0.4 to 0.7 wt.%, based on the total mass of the molding material to be produced. The smectite-containing clay to be used in the process according to the invention is preferably bentonite.particularly preferably selected from the group consisting of sodium bentonite and calcium bentonite and mixtures thereof. The mold base material is preferably selected from the group consisting of quartz sand, olivine sand, chromium ore sand, zircon sand, and artificially produced ceramic sands, and mixtures of these sands. Typically, a clay-bound mold contains at least 40% sand, preferably over 50% sand, particularly preferably over 60% sand, and most preferably over 70% sand. The process is preferably designed such that at least 90% by weight of the mold material is exposed to a temperature of at most 1000°C during casting. At temperatures above 1000°C, aluminum hydroxide is irreversibly converted into corundum (α-aluminum hydroxide), which cannot be converted back into aluminum hydroxide in a later cycle by adding water and is therefore no longer capable ofto act as an additive to be used according to the invention as defined above. Therefore, it is preferred that less than 50 wt.%, preferably less than 25 wt.%, and particularly preferably less than 10 wt.% of the Al2O3 contained in the molding material is in the form of corundum. The molding material produced in the later cycle of the process according to the invention preferably has the following parameters: - a compressibility in the range of 25% to 55%, determined according to VDG Data Sheet P37 (April 1997) and / or - a green compressive strength in the range of 8 N / cm² to 35 N / cm², determined according to VDG Data Sheet P38 (May 1997) and / or - a wet tensile strength of 0.10 N / cm² to 0.50 N / cm², determined according to VDG Data Sheet P38 (May 1997) and / or - a gas permeability of 70 to 200, determined according to BDG Guideline P41 (October 2013) and / or - an active clay content of 6 to 14%, determined by the methylene blue method according to VDG Data Sheet P035 (October 1999) and / or - a flowability of 20% to 90%,determined according to Morek Multiserw, technical documentation for the LUA-2e piling rig with electric drive, page 7. The molding material produced in the later cycle of the process according to the invention particularly preferably has the following parameters: - a compressibility in the range of 30% to 50%, determined according to VDG Data Sheet P37 (April 1997) and / or - a green compressive strength in the range of 10 N / cm² to 28 N / cm², determined according to VDG Data Sheet P38 (May 1997) and / or - a wet tensile strength of 0.20 N / cm² to 0.45 N / cm², determined according to VDG Data Sheet P38 (May 1997) and / or - a gas permeability of 90 to 160, determined according to BDG Guideline P41 (October 2013) and / or - an active clay content of 6 to 14%, determined by the methylene blue method according to VDG Data Sheet P035 (October 1999) and / or - a flowability of 50% to 90%, determined according to Morek Multiserw, technical documentation for the LUA-2e piling rig with electric drive,Page 7. Preferably, all of the stated parameters of the molding material are within the above-mentioned preferred, in particular particularly preferred, ranges. A further aspect of the present disclosure relates to the use of the above-defined additive in a process according to the invention as defined above. With regard to preferred additives and preferred process configurations, the above statements apply. The invention is described in more detail below with reference to the attached schematic figures. These show: Fig. 1 a molding material cycle (casting in coreless form) according to the prior art Fig. 2 a molding material cycle (casting in coreless form) according to the inventive process Fig. 3 a molding material cycle (casting in a form with a core) according to the prior art Fig. 4 a molding material cycle (casting in a form with a core) according to the inventive process One cycle of a molding material cycle,wherein the mold cast in step (3) does not contain an inserted core, comprises, according to Fig. 1 and Fig. 2, at least steps (1) to (5) as defined above. In step (1), a molding material is produced comprising (i) a first reprocessed molding material produced by reprocessing the cast molding material resulting from a previous cycle of the molding material cycle, which first reprocessed molding material does not comprise any material from cast cores, and (ii) additives. The additives comprise - one or more raw materials from the group consisting of - fresh molding base material (new sand), - as well as at least one reprocessed molding material from the group consisting of - a second reprocessed molding material produced by reprocessing uncast molds and / or cores and / or parts thereof, - a third reprocessed molding material produced by reprocessing molds and / or cores and / or parts thereof,which were produced and cast outside the molding material cycle shown in Fig. 1 or Fig. 2, - smectite-containing clay, preferably bentonite - water. The second processed molding material contains material from uncast molds, cores, and / or parts thereof, wherein the molds and / or cores were produced with an inorganic binder, and / or the third processed molding material contains material from cast molds, cores, and / or parts thereof, wherein the molds and / or cores were produced with an inorganic binder. Preferably, the inorganic binder contains water glass, in particular water glass hardened thermally or by gassing with CO2. The material from the cast molds and core comprises reaction products of the inorganic binder formed during casting. The processed molding materials preferably contain no organic binders.preferably no organic material at all. The processed molding materials preferably contain no carbon and no carbon carrier. In the process not according to the invention (Fig. 1), at least one lustrous carbon former is added as a further additive in step (1) during the production of the molding material. In the process according to the invention (Fig. 2), the additive defined above is added as a further additive in step (1) during the production of the molding material. The additive preferably contains or consists of aluminum trihydroxide. In step (2), a mold bound with smectite-containing clay is produced from the molding material produced in step (1). In step (3), a casting is produced by pouring the mold produced in step (2). The mold does not contain any inserted cores. In step (4), the casting produced in step (3) is separated from the mold, resulting in a cast molding material,which comprises material from a cast mold, but no material from cast cores. Preferably, before separation in step (4), the mold with the casting is cooled. In step (5), the cast molding material from step (4) is processed so that a first processed molding material is obtained for producing a new molding material in step (1) of a later, in particular the next, cycle. Preferably, before processing in step (5), the cast molding material is cooled. During processing, a portion of the cast molding material is discharged if necessary, so that a discharged molding material results. If a portion of the cast molding material was not already discharged during processing in step (5), a portion of the molding material produced in step (1) of the next cycle is discharged in order to keep the mass of the circulating molding material constant, so that discharged molding material results. In step (1) of a later,In particular, the next cycle, the first processed molding material resulting from step (5) of the earlier, in particular the previous cycle, is used to produce a new molding material as described above. A cycle of a molding material cycle, wherein the mold cast in step (3) contains at least one inserted core, comprises, according to Fig. 3 and Fig. 4, at least steps (1), (1a), (2), (2a), (3), (4), and (5) as defined above. In step (1), a molding material is produced comprising (i) the first processed molding material produced by processing the cast molding material resulting from an earlier cycle of the molding material cycle, which comprises material from cast cores produced with an inorganic binder, and (ii) aggregates. The aggregates comprise - one or more raw materials from the group consisting of - fresh molding base material (new sand),- and at least one processed molding material from the group consisting of - a second processed molding material produced by processing uncast molds and / or cores and / or parts thereof, - a third processed molding material produced by processing molds and / or cores and / or parts thereof that were produced and cast outside the molding material cycle shown in Fig. 3 or Fig. 4, - smectite-containing clay, preferably bentonite - water. In the process not according to the invention (Fig. 3), at least one lustrous carbon former is added as a further additive in step (1) during the production of the molding material. In the process according to the invention (Fig. 4), the additive defined above is added as a further additive in step (1) during the production of the molding material. The additive preferably contains or consists of aluminum trihydroxide. The processed molding materials preferably contain no organic binders.preferably no organic material at all. The prepared molding materials preferably contain no carbon and no carbon carrier. In step (1a), a molding material for producing at least one core (core molding material) is produced or provided. This molding material comprises a mold base material, an inorganic binder, and optionally additives. Suitable additives for molding materials for producing cores are known from the prior art. The binder is a conventional inorganic binder, e.g., a binder containing water glass. In step (2), a mold bonded with smectite-containing clay is produced from the molding material produced in step (1). In step (2a), at least one core is produced from the molding material (core molding material) produced or provided in step (1a) and inserted into the mold produced in step (2). In step (3), a casting is produced by pouring the mold produced in step (2).which contains at least one inserted core. In step (4), the casting produced in step (3) is separated from the mold, resulting in a cast molding material comprising material from the cast mold and material from the cast core. The material from the cast core comprises reaction products of the binder formed during casting. Preferably, before separation in step (4), the mold with the casting is cooled. In step (5), the cast molding material from step (4) is processed to obtain a first processed molding material for producing a new molding material in step (1) of a later, in particular the next, cycle. Preferably, the cast molding material is cooled before processing in step (5). During processing, a portion of the cast molding material is removed, if necessary.so that a discharged molding material results. If a portion of the cast molding material was not already discharged during processing in step (5), in order to keep the mass of the circulating molding material constant, a portion of the molding material produced in step (1) of the next cycle is discharged, resulting in discharged molding material. In step (1) of a later cycle, in particular the next cycle, the first processed molding material resulting in step (5) of the earlier cycle, in particular the previous cycle, is used to produce a new molding material as described above. The invention is further described below using non-limiting examples.

[0002] 0. Test methods and molding materials 0.1 Test methods The following test methods (measurement methods) were used (Table 1) Table 1: Measurement methods used Parameter / Property Measurement method / Definition Compactability (VDK), VDG Data Sheet P 37 (April 1997) Bulk density Green compressive strength (GDF) VDG Data Sheet P 38_Strengths (May 1997) Splitting strength VDG Data Sheet P 69_Binder test (October 1999) Shear strength 1 The dry compressive strength is specified according to P69 after a thermal loading of the test specimen for 3 hours (h) at 150 °C. Wet tensile strength (NZF) In addition, testing was carried out at the following times and temperatures: Dry compressive strength (TDF) 1)350 °C, 45 minutes (min) thermal stress at 450 °C and 30 min thermal stress at 750 °C. Flowability determined according to Morek Multiserw, Technical Documentation for the LUA-2e piling rig with electric drive, page 7. Gas permeability BDG Guideline P 41 (October 2013) (Gas permeability number) Water content VDG Data Sheet P 32_Water content of molding material (April 1997) VDG Data Sheet P 69_Binder test (October 1999) Active clay content (proportion of bindable clay, methylene blue value) VDG Data Sheet P 35_Methylene blue (October 1999) VDG Data Sheet P 69_Binder test (October 1999) Loss on ignition VDG Data Sheet P 33 (April 1997) Carbon, nitrogen, elemental analysis Sulphur contents (C, N, S) The elemental analysis of the elements C, N and S is carried out using the catalytic tube combustion method at 1140°C. Foreign gases are separated, and the measurement components are separated and detected using a thermal conductivity detector.A VARIO MAX CUBE elemental analyzer (from Elementar Analysensysteme GmbH) with application software is used. Surface roughness, roughness depth DIN EN ISO 4287 (July 2010) (Rz). The castings are blasted before roughness measurement. Blasting system: Model SMG160KP from MHG Strahlanlagen GmbH Blasting media: Hard cast iron blasting media Kantig HG 24 0.60 – 1.00 mm from Metalltechnik Schmidt GmbH & Co. KG Castings received with rib pattern device: 15 seconds on each rib surface with a blasting pressure of 600 kPa (6.0 bar) (castings received with molds corresponding to the rib pattern device) Castings received with sleeve pattern device: 5 seconds on each rib surface with a blasting pressure of 450 kPa (4.5 bar) (castings received with molds corresponding to the sleeve pattern device) AFS number Average grain size VDG data sheet P 34 (October 1999) Sludge content Degree of uniformity Sleeve and rib pattern devices as in (https: / / www.researchdisclosure.com / database / RD705032) and used in the following tests. 0.2 Materials used All information on raw material dosages refers to the pure raw material, i.e. as dry materials, without any moisture or hydration water. As part of the investigations, a molding material (hereinafter also referred to as the starting molding material) from the conditioned molding material circulation system of a brake disc foundry was used as the starting material for tests on converting molding material circulation systems that contain lustrous carbon formers. The molding material can be described by the following data (Table 2). Table 2: Parameters of the starting molding material P. arameter Molding material from the conditioned molding material circulation system of a brake disc foundry. Moisture content % (i.e. water content, see Table 1) 3,0Loss on ignition (900°C) % 3.5 Active clay content % 5.2 C % 2.5 N % 0.05 S % 0.02 AFS number 52 Average grain size mm 0.30 Sludge content % 10.1 Compactability % 45 Test specimen weight g 148 Green compressive strength N / cm² 18.2 Wet tensile strength N / cm² 0.31 Gas permeability 152 For the experimental investigations, processed molding materials made from core sands were used (second processed molding material as defined above). For this purpose, cores were produced with an organic binder or an inorganic binder and then grated through a circular vibrating screen from Webac. The starting material for a molding material produced with an organic binder are cores produced in the cold-box process using the binder Biocure 8568P1 / Silcure 8431P2 distributed by Hüttenes-Albertus Chemische Werke GmbH on a core shooter LL20 from Laempe.For this purpose, a type H32 sand from Quarzwerke was used, and 0.7 parts by weight of the binder components were dosed for 100 parts by weight of sand. The cores were produced at a firing pressure of 450 kPa (4.5 bar) and a firing time of 1.5 seconds. They were then cured by flowing 10 g of dimethylpropylamine (N,N-dimethylpropylamine, catalyst GH6 from Hüttenes-Albertus Chemische Werke GmbH) for 45 seconds at a gassing pressure of 200 kPa (2 bar). The starting material for a molding material produced with an inorganic binder is cores produced using the Cordis 9477 / Anorgit 9476 binder system distributed by Hüttenes-Albertus Chemische Werke GmbH on a Laempe LL20 core shooter. For this purpose, a sand of type H32 from Quarzwerke is used and 2.2 parts by weight of Cordis 9477 and 1.15 parts by weight of Anorgit 9476 of the binder components are dosed to 100 parts by weight of sand.The cores are produced with a shooting pressure of 450 kPa (4.5 bar) and a shooting time of 1.5 seconds in a core box heated to 180°C. For curing, the cores are blown through with hot air at 120°C at a gassing pressure of 200 kPa (2 bar) for 1 minute. The cores are grated using a circular vibrating screen (circular vibrating screen - 175056 pilot plant, Webac). The resulting molding material has the properties shown in Table 3. Table 3: Parameters of the processed molding materials from core sands Molding material from Molding material from inorganically bonded cores ColdBox cores Moisture content % 0.28 0.1 (i.e., water content, see Table 1) Loss on ignition (900°C) % 1.2 0.2 C % 1.04 0.06 N % 0.8 <NG S % < NG 0,01 AFS-Zahl 47 50 Schlämmstoffe % 0,2 0,5 Die Abkürzung NG zeigt an, dass die Messwerte unter der Nachweisgrenze liegen Ausgangsmaterial für unter den Versuchsbedingungen nicht zerfallende Kerne (d.h.Cores that do not disintegrate during separation (step (4)), see below, point 3, test series A), are quartz sand of the type HAP 0.20 / 0.315 / 0.40 from HA Polska and an inorganic binder consisting of water glass of the type Steinex 48 / 50 from Hüttenes-Albertus Chemische Werke GmbH in combination with Silica Fume Q1-Plus from RW Silicium. 100 parts by weight of quartz sand were mixed with 1.1 parts by weight of Silica Fume Q1-Plus and 3.4 parts by weight of Steinex 48 / 50 and formed into the core in a loose core box. The core was then gassed with 100°C hot CO2 in a Morek laboratory core shooter at a gassing pressure of 150 kPa (1.5 bar), thus curing. 1. Screening tests to identify suitable additives 6 kg of quartz sand (H32, Quarzwerke) are mixed in a mixer (pan mill mixer LM-2e, Morek MULTISERW) with 120 ml of water for 2 minutes at a speed of 40 rpm.Then, 0.48 kg of bentonite (dry weight) (Natroben 25F, Clariant) and 0.30 kg of additive (dry weight) are added and mixed for 7 minutes at a speed of 40 rpm. The resulting mixture is sieved by hand through a 3 mm sieve, and the compactability (CDC) of the material is then determined (testing equipment type: PVG; ID No.: 1501, year of manufacture: 2000). If the CDC is greater than 46.0%, the mixture is sieved again and the CDC measurement is repeated. This process is repeated until the CDC is below 46.0%. If the CDC is less than 44.0%, 7-12 ml of water are added and mixed for another minute, followed by sieving and CDC measurement. The addition of water is repeated until the VDK is above 44.0%.Three different state-of-the-art mixtures with lustrous carbon formers were used as references for the molding material properties: 1) a commercially available premix of 25% lustrous carbon former (“sea coal”) and 75% sodium bentonite (NEMIR 2575) from HA Italia SpA; 2) 5 parts by weight of coke flour (metallurgical coke) from LuxCarbon GmbH as lustrous carbon former and 8 parts by weight of bentonite (Natroben 25F, Clariant); 3) 5 parts by weight of Carboluxon 100 / P from Hüttenes-Albertus France as a commercially available lustrous carbon former and 8 parts by weight of bentonite (Natroben 25F, Clariant). In addition to the molding material properties, the casting quality is also a decisive criterion for selecting suitable additives. For this purpose, i.e. to check the casting quality, casting is carried out using the sleeve model device described in (https: / / www.researchdisclosure.com / database / RD705032), i.e.Molds manufactured according to the sleeve pattern setup described in (https: / / www.researchdisclosure.com / database / RD705032) are cast. The castings are then blasted, and the surface roughness is measured in accordance with DIN EN ISO 4287 (R_ISO). Two castings are examined, and the surfaces are measured three times each with a small, medium, and large spacing of the star-shaped ribs using a Mitutoyo SJ-500P surface measuring device over a measuring distance of 8 mm. No consistent trend can be determined with regard to the spacing of the ribs and the surface roughness; therefore, to simplify the evaluation, the average value of all measurements performed is used. This shows that the surface roughness of all castings obtained is within a range that allows commercial use. 1.1 Various types of aluminum hydroxide and magnesium hydroxide as additives. Al(OH)3 of type SH500 (SH500 nuance-00, Alteo) and type SH950 (SH950 nuance-00, Alteo) are used for the analysis of aluminum hydroxides. Brucite type 1, brucite type 2, and brucite type 3 from Ziegler & Co. GmbH are used for the analysis of magnesium hydroxides (Table 4, all values ​​according to Ziegler's technical data sheet dated October 2020). Table 4: Parameters of the brucite types used as additives Brucite type 1 Brucite type 2 Brucite type 3 Chemical analysis MgO 59.8% 63.2% 60.2% CaO 3.3% 0.2% 1.3% SiO2 5.6% 7.3% 7.1% Fe2O3 0.5% 0.7% 0.7% Loss on ignition 29.7% 28.5% 28.2% Physical properties Moisture <1% <1% <1% (i.e. water content, cf.Table 1) Bulk density 600 g / l 590 g / l 580 g / l Grain size (Cilas 920 laser granulometry) [µm] D98 53.0 52.9 53.5 D90 37.4 37.4 38.3 D50 9.6 9.7 9.9 D10 1.5 1.6 1.5 Table 5 shows the mold material properties and the roughness of the casting when using various hydroxides and the lustrous carbon formers 1) to 3) used as reference. Dry compressive strengths (TDF) of <35 N / cm are considered particularly positive. 2 and water contents of <2.8%, while dry compressive strengths of >50 N / cm 2 are considered negative, as are water contents of >3.2%. Hydroxides, especially aluminum hydroxide Al(OH)3 and magnesium hydroxide Mg(OH)2, enable the production of molds and exhibit good mold material properties (see Table 5). Table 5: Mold material properties and roughness of the casting when using various hydroxides or lustrous carbon formers as additives. n o d b P ix di x ) 1 5 r / 7 ) 2 a 0 or or C ) 30 1 d y d y 1 p 2 p 3 z n 5 e 2 z x z r e R n e u L n e n o hi 0 r t 0 5 hi 0 r t 5 9 y T y p y f I r t T T e M ef ( l r x h ef ul m ui H m S ui H i t i t i S c R E e u c u c u N R e e m s R o br n i n i rB r B r k a m B O C ul m ul K A A Compactability [%] 45.6 44.1 44.1 45.1 45.4 45.5 44.6 44.5 Weight of VDK test specimen [g] (test specimen for determining the compactability, cf. data sheet P 37) 159.2 168.4 162.2 162.8 161.0 164.1 168.6 168.5 Bulk density [g / cm³] 0.81 10.85 80.82 60.82 90.82 00.83 60.85 90.85 8 Test specimen weight [g] (test specimen for determining green compressive strength, shear strength and splitting strength) 152 155 147 152 152 151 152 153 Green compressive strength [N / cm²] 16.87 17.53 17.84 16.90 16.75 20.62 19.68 20.52 Shear strength (Green shear strength) [ N / cm²] 3.55 3.89 3.83 3.54 3.51 4.58 4.60 4.98Split strength (green split strength) [ N / cm²]2.97 3.02 3.28 2.94 2.84 3.78 3.57 3.74Wet tensile strength [N / cm²] 0.49 0.49 0.46 0.49 0.49 0.55 0.55 0.54 Gas permeability number 179 153 146 199 196 208 195 199 Water content [wt. %] 2.79 3.05 3.15 2.78 2.63 3.05 3.00 3.04 TDF 150°C / 3h [N / cm²] 29.9 46.3 32.3 36.6 32.1 53.9 48.2 40.4 TDF 350°C / 1.5h [N / cm²] 22.6 43.1 15.3 28.3 21.5 45.3 43.8 43.2 TDF 550°C / 45min [N / cm²] 23.2 41.8 19.5 34.9 22.1 43.0 40.0 34.2 TDF 750°C / 30min [N / cm²] 6.6 21.5 8.3 22.1 11.0 23.4 23.2 23.2 Surface roughness of the casting 102 150 73 150 151 [µm] 1.2 Investigation of aluminum hydroxide Al(OH)3 as an additive with addition of lustrous carbon formers The good values ​​for hydroxides, especially aluminum hydroxide Al(OH)3, can be further improved by the addition of lustrous carbon formers such as Carboluxon 100 / P, see Table 6.In particular, the surface roughness of the castings is reduced by the use of Carboluxon 100 / P, although the values ​​found using pure aluminum hydroxide are also sufficient. Table 6: Mold material properties and roughness of the casting when using Al(OH)3 SH 950 as an additive with the addition of the lustrous carbon former Carboluxon 100 / P d. i x or P / z d ) / P / / P / / P / n y 3 0 0 % 0 0 % % 0 0 % % 0 0 % h 0 z 1 0 1 0 1 01 0 01 0 e r i r 5 e n n 9 n ) 7 n 3 ) 5 n 5 ) f t 9e m ui H e r o ) 3 o )3 o S ef x ul H x O ul el h H x O ulel )3 o h o H x el O ul h R n i e o b (l o b o (lo (lo omR r A r K ( A br K ( A br K (u l a C a C a a A C C Compactability [%] 45.4 44.1 44.5 45.2 45.6 Weight of VDK test specimen [g] (test specimen for determining the compactability, cf. data sheet P 37) 161.0 162.2 164.3 161.4 159.5 Bulk density [g / cm³] 0.820 0.826 0.837 0.822 0.812 Test specimen weight [g] (test specimen for determining green compressive strength, shear strength and splitting strength) 152 147 150 150 150 Green compressive strength [N / cm²] 16.75 17.84 16.45 16.91 16.65 Shear strength (green shear strength) [ N / cm²] 3.51 3.83 3.63 3.72 3.56Split strength (green split strength) [ N / cm²]2.84 3.28 2.61 2.67 2.52 Wet tensile strength [N / cm²] 0.49 0.46 0.48 0.49 0.48 Gas permeability number 196 146 180 165 151 Water content [wt.%] 2.63 3.15 2.61 2.69 2.74 TDF 150°C / 3h [N / cm²] 32.1 32.3 24.9 29.0 26.8 TDF 350°C / 1.5h [N / cm²] 21.5 15.3 21.3 19.5 19.9 TDF 550°C / 45min [N / cm²] 22.1 19.5 14.7 16.9 15.4 TDF 750°C / 30min [N / cm²] 11.0 8.3 6.1 7.3 9.5 Surface roughness of the casting [µm] 150 73 150 116 83 1.3 Investigations of various carbonates as comparison additives While sufficiently good molding material values ​​cannot be achieved with huntite (trade name UltraCarb D98, obtained from LKAB Minerals), dolomite and manganese carbonate (obtained from TROPAG GmbH) show quite acceptable molding material values ​​(Table 7). The dolomites used were Bianco Zandobbio 0 / 50 micron from Ziegler and PE-DOL 90 from Possehl Erzkontor. Overall, the molding material values ​​are somewhat poorer than those when using the hydroxides described above.The values ​​nevertheless allow the materials to be used as a replacement for conventional lustrous carbon formers. However, carbonates have the disadvantage that they contain carbon. Table 7: Molding material properties when using various carbonates or lustrous carbon formers as additives. n o 8 b 9 0 9 ) 1 5 z 7 ) r P 2 a ) / 3 0 D 0 br L o O c n oi n 5 e 2 z C x 1 3 r u z R n e n O a C D - ai B b b r L n ( e r o x C a m r µ E P : ti o ef Ie M ef l h ef ul n t M l 3 5 : t d m n R E e e e o U N R m R br : i t i m ol a o Z s k a t o C n u l o D o K H DCompactability [%] 45.6 44.1 44.1 45.2 44.5 44.3 44.2 Weight of VDK test specimen [g] 159.2 168.4 162.2 163.0 169.1 164.9 165.9 (Test specimen for determining compactability, see Data Sheet P 37) Bulk density [g / cm³] 0.811 0.858 0.826 0.830 0.861 0.840 0.845 Test specimen weight [g] (Test specimen for determining green compressive strength, shear strength and splitting strength) 152 155 147 152 152 150 150 Green compressive strength [N / cm²] 16.87 17.53 17.84 17.04 19.28 18.53 17.65 Shear strength (green shear strength) 3.55 3.89 3.83 4.11 4.90 4.32 3.88 [N / cm²] Splitting strength (green splitting strength) 2.97 3.02 3.28 3.24 3.76 3.23 3.01 [N / cm²] Wet tensile strength [N / cm²] 0.49 0.49 0.46 0.49 0.55 0.53 0.53 Gas permeability number 179 153 146 224 205 229 233 Water content [wt.%] 2.79 3.05 3.15 3.08 3.68 2.80 2.74 TDF 150°C / 3h [N / cm²] 29.9 46.3 32.3 47.9 72.4 40.1 43.3 TDF 350°C / 1.5h [N / cm²] 22.6 43.1 15.3 56.7 55.5 37.7 42.2 TDF 550°C / 45min [N / cm²] 23.2 41.8 19.5 37.7 60.5 38.8 38.0 TDF 750°C / 30min [N / cm²] 6.6 21.5 8.3 17.2 18.0 17.6 18.5 The mold material properties can be improved by mixing carbonates with hydroxides (Table 8). MixMag is a 50% / 50% mixture of brucite (93% Mg(OH)2) with raw magnesite (92% MgCO3), which was purchased from Possehl Erzkontor GmbH & Co. KG, and Dolomag is a 50% / 50% mixture of brucite (93% Mg(OH)2) and dolomite (95% CaMg(CO3)2), which was also purchased from Possehl Erzkontor. Table 8: Mold material properties and roughness of the casting when using various carbonate-hydroxide mixtures 0. O 35 : 0 P ) / 030 0 ) 5 5: C n 1 3 ) 0 3 5) t ) 0 2 5 9 M z 1 h p g O g i h % n e n r o c e f x i y e l T a C a t i m x g mm M ol ol ci H S 0 5o e l ) 3 , 3e ul g c i o g ) R o r b u M+2 D r H H r e a V r B ) H D + ti e c V O (l O A (l C O( u A g r M B ( ( % 05Compactability [%] 44.1 44.5 45.8 45.2 45.4 45.7 Weight of VDK test specimen [g] (test specimen for determining the compressibility, cf. data sheet P 37) 162.2 168.5 161.2 163.4 161.0 161.2 Bulk density [g / cm³] 0.826 0.858 0.821 0.832 0.820 0.821 Test specimen weight [g] (test specimen for determining green compressive strength, shear strength and splitting strength) 147 153 151 152 152 150 Green compressive strength [N / cm²] 17.84 20.52 18.71 19.08 16.75 16.79 Shear strength (green shear strength) [ N / cm²] 3.83 4.98 4.54 3.90 3.51 3.72Split strength (green split strength) [ N / cm²]3.28 3.74 3.42 3.22 2.84 2.77Wet tensile strength [N / cm²] 0.46 0.54 0.61 0.54 0.49 0.48 Gas permeability number 146 199 216 214 196 192 Water content [wt. %] 3.15 3.04 2.80 2.78 2.63 2.66 TDF 150°C / 3h [N / cm²] 32.3 40.4 37.9 46.7 32.1 31.7 TDF 350°C / 1.5h [N / cm²] 15.3 43.2 44.4 40.2 21.5 26.8 TDF 550°C / 45min [N / cm²] 19.5 34.2 32.1 37.1 22.1 22.4 TDF 750°C / 30min [N / cm²] 8.3 23.2 20.7 15.5 11.0 8.1 Surface roughness of the casting [µm] 151 175 180 150If a state-of-the-art lustrous carbon former such as Carboluxon 100 / P is added to a mixture of hydroxide and carbonate, the molding material properties can be further improved (Table 9). Table 9: Molding material properties when using various carbonate-hydroxide mixtures with the addition of Carboluxon 100 / P as lustrous carbon former P % 0 % % ) / 3 0 ) / 1 0 0 P / 3 / 5. 0 / P / P z1 1 % nh g 0 0 % 0 0 0 % / 0 0 0 0 e n r o c a 9 ef x i u e m g 1 7 g 1 5 g1e l l gr x i a n m o a n o a n o R o br e M x i x u a V Ml m x i x o u m x Ml i x o ul o C br a b M r br C a C aC Compactability [%] 44.1 45.8 44.1 45.6 45.0 Weight of VDK test specimen [g] 162.2 161.2 166.4 160.9 162.3 (Test specimen for determining compactability, see data sheet P 37) Bulk density [g / cm³] 0.826 0.821 0.847 0.819 0.827 Test specimen weight [g] (Test specimen for determining green compressive strength, shear strength and splitting strength) 147 151 150 150 150 Green compressive strength [N / cm²] 17.84 18.71 19.54 18.49 18.69 Shear strength (green shear strength) 3.83 4.54 4.26 3.98 3.96 [N / cm²] Splitting strength (green splitting strength) 3.28 3.42 3.45 3.25 3.24 [N / cm²] Wet tensile strength [N / cm²] 0.46 0.61 0.54 0.52 0.50 Gas permeability number 146 216 208 196 180 Water content [wt. %] 3.15 2.80 2.74 2.90 2.92 TDF 150°C / 3h [N / cm²] 32.3 37.9 39.8 33.6 35.9 TDF 350°C / 1.5h [N / cm²] 15.3 44.4 29.5 24.2 19.3 TDF 550°C / 45min [N / cm²] 19.5 32.1 27.1 22.1 21.3 TDF 750°C / 30min [N / cm²] 8.3 20.7 9.8 11.2 9.9 1.4 Emissions of the bentonite and additives used Table 10 shows emission measurements of the bentonite and additives used. The emission measurements were carried out at the Foundry Institute of the University of Freiberg; for this purpose, the materials were introduced into a tube furnace at 900°C, and the resulting emissions were measured using online FT-IR; calibration was carried out using test gases. The emissions of the additives to be used according to the invention are significantly lower than those of conventional lustrous carbon formers such as the coke meal from LuxCarbon described above or the product Carboluxon 100 / P. Carbonates (not according to the invention) such as manganese carbonate reduce the emissions of hydrocarbons, particularly benzene, toluene, and xylene, but, as expected, lead to significantly increased CO2 emissions compared to hydroxides such as Al(OH)3.According to the invention, carbonates are therefore preferably used in combination with hydroxides. Table 10: Results of emission measurements using different additives (all figures in mg / kg, i.e., mg of the respective emission per kg of material). i l l o a l l e z O O 2H4H 4 H OO 2 ht o z o ul l ol n e C C C C 2 h P H C h n p e a B o T y b X l y N ht E Sodium bentonite 50 3242 6 0 0 1 0 3 1 0 0 Hard coal 3710 8549 12155132 71 62 63 278 6 1 3 Carboluxon 100 / P 4208 1275215155966 91 78 73 307 10 1 2 Al(OH)335 2957 4 0 0 1 0 5 1 0 0 MnCO316 17654 4 0 0 1 0 5 1 0 0

[0003] 2. Production and testing of molding materials in a closed-loop system. The objective of these experiments is to cast and recycle a specific quantity of molding material several times. As is common practice in industrial foundries, the molding material is recycled. During each reprocessing of the molding material, additives are added, which increase with each cycle. Components present in the initial molding material but no longer added decrease, i.e., the proportions of components that are no longer added in subsequent cycles decrease. The total quantity of molding material in the cycle remains constant at approximately 8 kg. Two molds are produced and cast per cycle according to the sleeve pattern setup described in (https: / / www.researchdisclosure.com / database / RD705032). To illustrate the test procedure, reference is made to the molding material cycle in Fig. 2.The mold material cycle comprises the following steps: Production of the mold material (step (1), first cycle) Test series 2.1, 2.2.1, 2.2.2, 2.3.1, 2.3.2 as described below. In the first cycle, 6 kg of quartz sand type H32 from Quarzwerke are used. The mold base material is then mixed with 480 g of sodium bentonite (Natroben 25F, HA ITALIA SpA, which is a Na-bentonite produced by activating a natural Ca-bentonite), 300 g of the respective additive, and 120 ml of water in a Morek Multiserw pan mill mixer for 1 minute without water, and then mixed again 7 minutes after the water has been added. For this purpose, the molding base material is first mixed with 120 ml of water on a Morek Multiserw pan mill mixer for 1 minute, and then, after adding 480 g of sodium bentonite (Natroben 25F, HA ITALIA SpA) and 300 g of the respective additive, the mixture is mixed again for 7 minutes on a Morek Multiserw pan mill mixer.Test series 2.4-2.6 as described below. In the first cycle, 3.7 kg of quartz sand type H32 from Quarzwerke are used. The mold base material is then mixed with 322 g of Volclay (GEKO™ V foundry bentonite from Clariant Deutschland GmbH, a naturally occurring sodium bentonite), 207 g of the respective additive, and 130 ml of water in a Morek Multiserw pan mill mixer for 1 minute without water, and then mixed again 7 minutes after the water has been added. To do this, first, the mold base material is mixed with 130 ml of water in a Morek Multiserw pan mill mixer for 1 minute, and then, after adding 322 g of Volclay and 207 g of the respective additive, mixed again for 7 minutes in a Morek Multiserw pan mill mixer. The following statements apply to all test series 2.1 to 2.6 (unless otherwise stated). During each production (step (1)) of the molding material, additives are added, which increase with each cycle.By removing part of the cast molding material in step (5) or in step (1) of the next cycle (see Figure 2), the proportion of components that are present in the initial molding material but are no longer added is reduced. Manufacturing the mold (step (2) in all cycles) For this purpose, the molding material is filled into the mold of the sleeve pattern device 3 minutes after mixing and compacted in two pressing processes (filling, pressing, refilling, pressing). The process is completed in a further 3 minutes. Two molds are produced per test. Pouring (step (3) in all cycles) The molds are poured one after the other after a waiting time of 30 minutes. The mold is poured with liquid metal of the alloy GJL 250 at 1450 °C using a pouring ladle. The poured mold stands overnight until it is separated. The casting cools down and the molding material first heats up and then cools down in the mold overnight.Separation (step (4) in all cycles) The casting and the poured molding material are separated. Preparation (step (5) in all cycles) The molding material is filled into a storage container and the molding material lumps are crushed. Metal residues are removed. Production of the molding material (step (1) in the 2nd and each subsequent cycle) A new molding material is produced by refreshing the processed molding material from the previous cycle (first processed molding material) by adding bentonite, water, additive (as defined above) and fresh molding material (new sand) or a second processed molding material produced by processing cores (see below for details). Fresh base material or a second prepared molding material, produced by preparing cores (see below for details), is added to the prepared molding material from the previous cycle and mixed with 120 ml of water for 1 minute, and then after adding sodium bentonite (Natroben 25F, HA ITALIA SpA, test series 2.1, 2.2.1, 2.2.2, 2.3.1, 2.3.2) or Volclay (foundry bentonite GEKO™ V from Clariant Deutschland GmbH, test series 2.4, 2.5 and 2.6) and the respective additive (quantities of bentonite and additive see below) are mixed for a further 7 minutes on a Morek Multiserw edge mill mixer. The increase in quantity of molding material due to additions in the mixer, i.e. the increase in quantity of molding material resulting from the addition defined above, is regulated by removing the same quantity of ready-mixed molding material in each cycle. Each time the molding material is manufactured (step (1)), additives are added, which increase with each cycle. By removing a portion of the cast molding material, the proportion of components present in the initial molding material but no longer added in subsequent cycles is reduced. 2.1 Additive Al(OH)3 orMg(OH)2 when fresh mold base material is added in subsequent cycles (not according to the invention). Ten cycles (0-9) are carried out using the sleeve model equipment described in (https: / / www.researchdisclosure.com / database / RD705032). The first test is carried out with 100% fresh mold base material of type H32 from Quarzwerke. In all subsequent cycles 1 to 9, 4 kg of the used mold material from the previous casting is used and refreshed with 400 g of mold base material (fresh mold base material), 64 g of bentonite, and 20 g of the respective additive. SH950 nuance-00 from Alteo is used as the aluminum hydroxide Al(OH)3 additive. The results of the tests with Al(OH)3 are shown in Table 11. Brucite Type 3 from Ziegler & Co. GmbH is used as the magnesium hydroxide additive Mg(OH)2. The results of the tests with Mg(OH)2 are shown in Table 12.When used with fresh mold base material as an aggregate (see Figure 2, step (1)), both additives exhibit good molding properties and a comparable surface quality, which can be seen in the measured roughness of the castings. Al(OH)3 as an additive results in a higher active clay content and a significantly lower loss on ignition. For both Al(OH)3 and Mg(OH)2, the mold material properties and the castings are of good quality. The surface roughness of the castings is correspondingly low.

[0004] Table 11: Characteristic values ​​of samples taken in the respective cycles to determine the mold material properties with Al(OH)3 as additive, and surface roughness of the casting f f ti ti r ot % tl ti e k - e g h k e t s ] tl a e k gi t t s i sl gi s li s et m r a h h e ] r a s ] ² u l s ä h u et ul k i y e o r f % s . e w g gr % . w bt ] ef k m c r e v ] l h a ar s ] c zs n s u m Z e b g f n e n e G ot s s e h G c % i [ c / h % [ r ti e µ [ d ur N [ ül u e h c Gu a [ A g s vi t a [ r e d d n G s k äl f s e u k W V ü r a r e d A A G G b O 0 100% 6.4% 2.5% 43% 15.8 2.12 179 150 1 78% 6.5% 2.5% 43% 19.8 2.06 174 148 2 69% 7.3% 2.7% 44% 20.6 1.98 188 144 3 61% 8.0% 2.8% 41% 21.4 1.91 189 151 4 53% 7.4% 2.9% 43% 23.1 1.85 198 168 5 47% 6.9% 2.9% 40% 23.2 1.86 195 163 6 42% 7.4% 3.1% 43% 23.5 1.86 200 152 7 37% 8.0% 3.3% 45% 22.3 1.74 216 173 8 32% 7.7% 3.3% 43% 22.1 1.85 224 175 9 29% 8.6% 3.4% 45% 21.2 1.81 236 174 Mean 7.4% 2.9% 43% 21.3 1.90 200 160S tandard- a bweichung 0.7% 0.3% 1.4% 2.2 0.11 19 11

[0005] Table 12: Characteristic values ​​of samples taken in the respective cycles to determine the mold material properties with Mg(OH)2 as an additive, and surface roughness of the casting f ft r o i t t t e s tl t e i e i e a tl i e k g t k g h u s li s t u e l t i m r ] % h a e h e ] k % r i a t s e ] ² s u i l s s ar n et s ] k e o y r f s . w g n ] % gr . w bt ] % f k m r c e v ] ä % l h e h s u m Z e b gf n e o tv [ e e h [ c / is s G c i ur N [ h ü [ cr c µ äl G [ u a A g G [ t s k a [ dr d l u d fr s e u A W e V n ü G s e d A r G a G b O 0 100% 5.7% 2.6% 42% 18.9 2.08 177 158 1 78% 4.9% 3.0% 43% 22.3 2.11 204 154 2 69% 5.1% 3.1% 43% 22.5 2.16 218 149 3 61% 5.5% 3.2% 42% 22.0 2.21 223 167 4 53% 6.2% 3.2% 43% 22.9 2.24 220 180 5 47% 5.9% 3.2% 40% 22.8 2.26 205 157 6 42% 6.5% 3.4% 42% 22.5 2.25 210 169 7 37% 6.2% 3.6% 42% 21.0 2.25 186 157 8 32% 7.4% 3.4% 42% 22.7 2.21 199 167 9 29% 7.0% 3.5% 42% 23.0 2.22 206 183 Mittel 6.0% 3.2% 42% 22.1 2.20 205 164S tandard-a bweichung0.8% 0.3% 0.9% 1.2 0.06 14 102.2 Al(OH)3 and Mg(OH)2 when adding ColdBox core sand in subsequent cycles (not according to the invention) 31 cycles (0-30) are carried out using the sleeve model device described in (https: / / www.researchdisclosure.com / database / RD705032). The test procedure and measurement of the molding material and casting properties are carried out as described in Chapter 2.1, but in subsequent cycles, instead of fresh mold base material, a second processed molding material (see Fig. 2, step (1)) produced by processing uncast cores (for the proportion of the produced molding material, see Tables 13 and 16) that had been produced with ColdBox binder ("ColdBox core sand") is added. 2.2.1 Aluminum hydroxide Al(OH)3 with addition of ColdBox core sand in subsequent cycles. When using aluminum hydroxide Al(OH)3, the molding material properties with a 5% addition of ColdBox core sand are so stable that from cycle 15 onwards the addition is increased to 10% ColdBox core sand (Tables 13 and 14). Furthermore, the molding material properties remained stable. Table 13: Composition and compactability of the molding material mixture in the individual cycles. s n g u n g n g n u tl ti u ul r e m i f ur u r r a e k s a k y i s d f o ei r e ei h r u l ff k o Z ] o y t d g n a t s ] s o g i so g s o l m e gr ] a bt ] Z s m g [ d n m i s m r % [ d ti n i d n i d r e r n e s % [ h c % [ o g n i F r a n o s r e o F n o v t i ti e i s i d s s a dr v nr e e K n d W K e B A a W V0 6000 300 4,8 480 300 120 2,55 42,0 1 3800 190 9,3 26,6 22,8 50 2,79 45,0 2 3750 188 13,6 26,3 22,5 50 2,84 45,0 3 3800 190 17,7 26,6 22,8 50 3,01 45,9 4 3800 190 21,7 26,6 22,8 50 3,05 45,1 5 3800 190 25,4 26,6 22,8 50 3,01 41,5 6 3800 190 28,9 26,6 22,8 50 2,98 38,9 7 3800 190 32,3 26,6 22,8 50 2,97 38,1 8 3750 188 35,5 26,3 22,5 50 3,26 44,1 9 3750 188 38,6 26,3 22,5 50 3,47 47,0 10 3750 188 41,5 26,3 22,5 50 3,49 44,5 11 3700 185 44,3 25,9 22,2 50 3,54 45,2 12 3700 185 47.0 25.9 22.2 50 3.65 43.9 13 3750 188 49.5 26.3 22.5 50 3.72 46.2 14 3800 190 51.9 26.6 22.8 50 3.82 44.0 15 3800 380 56.3 41.8 32.3 50 3.69 44.0 16 3800 380 60.3 41.8 32.3 50 3.52 41.2 17 3800 380 63.9 41.8 32.3 50 3.63 42.0 18 3800 380 67.2 41.8 32.3 50 3.48 40.0 19 3800 380 70.1 41.8 32.3 50 3.56 41.0 20 3800 380 72.9 41.8 32.3 50 3.51 42.5 21 3800 380 75.3 41.8 32.3 50 3.57 42.7 22 3800 380 77.6 41.8 32.3 50 3.72 44.5 23 3800 380 79.6 41.8 32.3 50 3.70 42.0 24 3800 380 81.5 41.8 32.3 50 3.74 45.0 25 3800 380 83.1 41.8 32.3 50 3.76 44.5 26 3800 380 84.7 41.8 32.3 50 3.56 43.0 27 3800 380 86.1 41.8 32.3 50 3.58 41.5 28 3800 380 87.3 41.8 32.3 50 3.62 42.0 29 3800 380 88.5 41.8 32.3 50 3.67 46.0 30 3800 380 89.5 41.8 32.3 50 3.68 46.0 Average 3.4 43.4 Table 14: Characteristic values ​​of samples taken in the respective cycles f. f t r o i t t e e s l k - g ] a g i is l ti s t u e l t m r % h e t s e ] ² F Z ] ² s äl h e kr k i e o r f s . w g n f k m c N* m c h a c z a y Z e b g n e o t % c u / N0 / N r u s ti b ß % f u a G [ v it r d [ 0 1 [ d e k e i A g s k n s l u A ü r a F A G G0 100% 5.7 16.0 41.0 149 50.5 1 93% 18.0 49.5 168 52.0 86% 18.8 49.2 169 51.3 80% 18.1 48.1 166 51.3 75% 19.0 47.8 170 51.0 69% 17.3 37.6 164 49.5 64% 19.8 38.8 152 49.5 60% 18.8 38.4 156 49.5 56% 18.9 35.7 166 50.5 52% 18.8 37.8 166 51.9 48% 18.4 38.5 170 51.6 45% 18.9 33.2 173 52.0 41% 17.6 35.8 185 51.5 38% 5.9 17.6 35.5 174 52.0 36% 17.6 35.2 182 52.2 32% 18.4 32.0 163 51.9 28% 19.7 31.3 155 51.2 25% 6.1 18.8 36.1 149 52.0 22% 18.5 32.9 150 52.0 19% 17.8 32.4 149 52.1 17% 5.8 19.8 30.1 154 51.5 15% 17.9 29.8 161 51.5 13% 16.8 34.9 155 52.6 12% 17.8 33.0 165 52.2 10% 16.6 32.9 155 52.9 9% 17.9 36.2 154 51.7 8% 17.8 31.7 156 52.1 7% 19.3 33.1 158 52.1 28 6% 6.2 18.9 35.4 170 51.0 29 6% 17.3 39.6 163 52.0 30 5% 6.2 18.5 34.5 166 51.5 Average 6.0% 18.2 36.7 162 51.5% The data from the CNS analysis of the molding materials from the different cycles show the increase in the carbon and nitrogen contents that come from the addition of ColdBox core sand.The surface roughness of the castings is improved compared to the test series with the addition of new sand (see above 2.1) instead of cold-box core sand. This is attributable to the addition of the core sand (Table 15). Table 15: CNS analysis of selected cycles and surface roughness of the corresponding castings f. f r ot r e s t s ) - s l et m] ] ] 1 ( n i e e- d - ] n s m µ k i r o % % . % ] e h ti t s ] dr g n e h e d [ ul y er f s . w . w % . c ä e h s m a d u c ä ti sli Z e b g w f n What is N e S , l f u a G w r u u µ [ n h c l f e et [ G [ G [ e e a r G S at i e r e h u s s A g s G u [ b A e S d w b b Oa r u G A a1 93% 0.25 0.01 < NG 153 9 4 75% 0.38 0.02 < NG 154 14 8 56% 0.49 0.03 < NG 116 8 12 41% 0.58 0.04 < NG 151 13 14 36% 0.6 0.04 < NG 16 28% 0.69 0.05 < NG 138 7 18 22% 0.73 0.05 < NG 20 17% 124 15 22 13% 0.78 0.06 < NG 24 10% 106 9 26 8% 0.85 0.06 < NG 30 5% 0.9 0.06 < NG 114 12 (1) The abbreviation NG indicates that the measured values ​​are below the detection limit 2.2.2 Mg(OH)2 when adding ColdBox core sand in subsequent cycles With magnesium hydroxide Mg(OH)2in the form of brucite type 3 as an additive, it becomes apparent after just a few cycles that the properties of the molding material cannot be kept stable. Therefore, the bentonite content of the molding material is increased in cycles 8 and 14 (Table 16). Despite this, there is no stabilization of the molding material properties (Table 17). In particular, the wet tensile strength decreases with increasing number of cycles and this trend can only be counteracted in the short term by adding more fresh bentonite.Table 16: Composition and compactability of the molding material mixture in the individual cycles. s l u ul i k d et t ] l ti t a ] e k s a y n n i v r h r u l ff o Z ] a a s ] d % n . n ot ] i ti ] es s ] l e g % a r . bt ] k y t g [ n g [ w g [ d g [ Z s m m r e r a s e n e d a m [ e s w e h c i % [ O gi e K nr G [ B A W s G [ dr F r o v e a K We V 0 6000 300 4.8 480 300 120 2.6 42.9 1 3800 190 9.3 19.0 13.3 50 2.5 42.5 2 3750 188 13.6 18.8 13.1 50 2.6 39.9 3 3800 190 17.7 19.0 13.3 50 2.8 42.2 4 3800 190 21.7 19.0 13.3 50 2.9 40.0 5 3800 190 25.4 19.0 13.3 50 2.9 39.5 6 3800 190 28.9 19.0 13.3 50 3.0 40.0 7 3800 190 32.3 19.0 13.3 50 3.2 44.0 8 3750 188 35.5 76.09 13.3 70 3.4 42.1 9 3750 188 38.6 26.3 13.1 60 3.5 41.5 10 3750 188 41.5 26.3 13.1 70 3.4 42.9 11 3700 185 44.3 26.3 13.1 70 3.5 41.3 12 3700 185 47.0 26.3 13.1 70 3.7 44.0 13 3750 188 49.5 26.3 13.1 70 3.7 40.5 14 3800 190 51.9 34.04 13.3 100 4.3 42.5 15 3800 190 54.2 34.04 13.3 90 4.2 39.5 16 3800 190 56.4 34.04 13.3 80 4.1 40.0 17 3800 190 58.5 34.04 13.3 80 4.0 39.0 18 3800 190 60.4 34.04 13.3 80 4.4 43.5 Average 3.4 41.5 Table 17: Characteristic values ​​of samples taken in the respective cycles f f r ot t - - e s t s l gi t g i t u e lt i m r ] a h s s s l i e e o r f % e e f s . w g n ] k c t ] i ² F Z ] ² äl h e m a kr c N m h z a ] k y Z e b g e o % [ u k / * f n 0 c / cr s ti b % [ u a G tv i r d N [ 0 N [ u ß d e e i A g [ t s k n ü 1 s k l u A r a F A G G0 87.0 4.8 18.2 44.6 154 50.0 1 82.8 5.2 20.1 34.3 154 50.0 2 78.9 4.1 21.4 27.0 150 49.8 3 75.1 3.1 19.8 18.4 142 50.6 4 71.5 3.1 20.4 14.4 139 49.6 5 68.1 2.0 18.1 9.6 142 48.6 6 64.9 2.0 20.0 9.1 132 49.5 7 61.8 1.9 16.9 6.1 132 50.2 8 58.9 3.6 21.9 14.1 137 50.0 9 56.0 3.3 20.7 13.6 133 51.3 10 53.4 3.4 21.1 9.0 136 51.2 11 50.8 3.2 21.7 10.2 131 50.6 12 48.4 2.9 21.4 12.2 137 51.3 13 46.1 3.3 22.3 9.3 124 50.9 14 43.9 6.2 21.8 18.3 128 51.7 15 41.8 6.9 23.2 21.3 123 50.8 16 39.8 6.2 23.6 22.3 125 50.5 17 37.9 5.4 23.5 20.8 126 51.5 18 36.1 4.8 22.1 17.5 133 52.5 As expected, the carbon content and, to a limited extent, the nitrogen content of the molding material increase when ColdBox core sand is added (Table 18). The surface roughness of the castings is good and is not negatively affected. In contrast to aluminum hydroxide Al(OH)3 (see test series 2.2.1 above), magnesium hydroxide Mg(OH)2 allows for the addition of organic core sand (i.e., ColdBox core sand, see) but no molding material cycle with stable molding material properties (Table 17). Table 18: CNS analysis of selected cycles and surface roughness of the corresponding castings f. r ot r ] e t s ] - n s - e d - n s m s et m i r ] ] o % . % % ) e h e d sl i ] dr g n e h e d µ[ u l k e y r f Z e s b g w . w . w1 ( c ä ti et s m a d u c ä ti sl i f n e Ce N e S % l fr e h s u µ [ n h a ci l fr e h et u aG A g [ s f G [ G [ e b u a u O r G t S e e w b u b a s r s u A a O G1 82.8 0.33 0.01 < NG 144 14 4 71.5 0.45 0.02 < NG 149 11 8 58.9 0.61 0.03 < NG 128 10 12 48.4 0.74 0.04 < NG 140 7 14 43.9 0.79 0.04 < NG 16 39.8 0.82 0.04 < NG 132 10 18 36.1 0.84 0.04 < NG 148 16 (1) The abbreviation NG indicates that the measured values ​​are below the detection limit 2.3 Al(OH)3 and Mg(OH)2 when adding inorganically bound core sand in the subsequent cycles In each case 31 cycles (0-30) were carried out using the sleeve model device described in (https: / / www.researchdisclosure.com / database / RD705032). The test procedure and measurement of the molding material and casting properties are carried out as described in Chapter 2.1, however, in the subsequent cycles, instead of fresh molding material, a second prepared molding material (see Fig. 2, step (1)) prepared by preparing uncast cores is added (for the proportion of the prepared molding material, see Table 19 or22) that were produced with an inorganic binder (water glass) ("IOB core sand"). This is therefore an inorganic molding material cycle with regard to all binders used. 2.3.1 Aluminum hydroxide Al(OH)3 as an additive when adding inorganically bound core sand in subsequent cycles. Even when adding IOB core sand, the use of aluminum hydroxide Al(OH)3 results in a molding material cycle with stable molding material properties, so that the addition of IOB core sand is increased to 10% from cycle 15 onwards (Tables 19 and 20). Table 19: Composition and compactability of the molding material mixtures in the individual cycles s s. u u l l i t ti s a k y ] e ul ff Z g [ t l n ] ti a e k k o ] d a d % . n vi t r e h r s ]l e g ] a b ] y t Z s m e m r g g i [ n a n s a w ot ] g i d ] g s r s e n e [ d [ a m [ e s % [ t h c % [ o r e nr e nr G A W s i e [ B a dr F hr K W e o v K V0 6000 300 4,8 480 300 120 2,6 44,0 1 3800 190 9,3 26,6 22,8 50 2,7 46,0 2 3750 188 13,6 26,3 22,5 50 2,8 44,8 3 3800 190 17,7 26,6 22,8 50 2,9 46,0 4 3800 190 21,7 26,6 22,8 50 3,0 43,9 5 3800 190 25,4 26,6 22,8 50 3,0 41,0 6 3800 190 28,9 26,6 22,8 50 3,0 40,8 7 3800 190 32,3 26,6 22,8 50 3,2 42,1 8 3750 188 35,5 26,3 22,5 50 3,3 44,6 9 3750 188 38,6 26,3 22,5 50 3,3 43,1 10 3750 188 41,5 26,3 22,5 50 3,4 46,5 11 3700 185 44,3 25,9 22,2 50 3,4 42,6 12 3700 185 47,0 25,9 22,2 50 3,5 43,0 13 3750 188 49,5 26,3 22,5 50 3,5 43,1 14 3800 190 51,9 26,6 22,8 50 3,5 41,8 15 3800 380 56,3 41,8 32,3 50 3,4 39,5 16 3800 380 60,3 41,8 32,3 50 3,5 42,0 17 3800 380 63,9 41,8 32,3 50 3,7 46,0 18 3800 380 67,2 41,8 32,3 50 3,5 46,0 19 3800 380 70,1 41,8 32,3 50 3,5 42,5 20 3800 380 72,9 41,8 32,3 50 3,5 43,0 21 3800 380 75,3 41,8 32,3 50 3,5 42,0 22 3800 380 77,6 41,8 32,3 50 3,7 44,2 23 3800 380 79,6 41,8 32,3 50 3,7 44,5 24 3800 380 81,5 41,8 32,3 50 3,9 46,0 25 3800 380 83,1 41,8 32,3 50 3,7 44,0 26 3800 380 84,7 41,8 32,3 50 3,5 41,0 27 3800 380 86,1 41,8 32,3 50 3,6 42,5 28 3800 380 87,3 41,8 32,3 50 3,7 42,5 29 3800 380 88,5 41,8 32,3 50 3,7 43,5 30 3800 380 89,5 41,8 32,3 50 3,7 43,5 Average 3,4 43,6 Table 20: Characteristic values ​​of samples taken in the respective cycles f, f t r o i t t e l e k - g s t s u e l t i m r ] a h g it i so f % ] . e g ] s e f ² F m Z ] ² s ä l ti e m l h h a kr ] k er s w n k N z a y Z e b g e o % [ c c / * f n 0 c / cr s t b% [ u a G [ tv it ur N [ 0 N [ u i e ß e A g d 1 d k i s k l u A n s ü a F A r G G0 87.0 5.7 17.5 44.5 146 50.5 1 82.8 18.0 49.4 160 50.8 2 78.9 20.7 48.9 150 50.5 3 75.1 19.2 48.7 155 50.5 4 71.5 21.7 48.6 155 50.7 5 68.1 20.3 48.1 163 49.1 6 64.9 22.5 47.7 155 49.5 7 61.8 19.9 46.4 164 50.0 8 58.9 21.4 48.7 173 50.8 9 56.0 20.7 48.7 170 52.7 10 53.4 21.3 45.5 172 52.3 11 50.8 21.2 47.5 185 51.6 12 48.4 21.7 48.0 180 52.4 13 46.1 5.7 21.5 48.4 180 52.0 14 43.9 20.8 46.3 173 52.2 15 39.9 22.2 36.5 142 51.0 16 36.3 21.7 37.6 156 51.5 17 33.0 5.7 20.7 38.2 153 52.5 18 30.0 20.1 37.5 166 52.5 19 27.3 21.4 34.4 155 51.8 20 24.8 5.5 21.8 34.6 162 52.5 21 22.5 21.6 36.5 162 52.0 22 20.5 20.5 37.6 160 52.5 23 18.6 20.5 39.6 169 52.5 24 16.9 18.7 38.1 156 53.0 25 15.4 21.8 36.5 151 51.5 26 14.0 6.1 22.7 35.7 149 51.0 27 12.7 22.3 34.6 147 51.9 28 11.6 5.9 21.7 36.5 184 51.0 29 10.5 21.2 40.2 177 51.5 30 9.6 5.8 21.2 39.4 176 51.0 Average 5.8% 20.9 42.2 162.8 51.5The molding material analyses (Table 21) show that there is no significant enrichment of carbon,Nitrogen or sulfur in the molding material; C-containing (carbon-containing) components from the inorganic binder (such as surfactants) are of minor importance. The low C (carbon) load is one of the major advantages of this inorganic molding material cycle, as only very low emissions are to be expected (see below). Despite the lower carbon content, the obtained surface roughness values ​​(Table 21) are very close to those of the tests with coldbox core sand (test series 2.2.1). Table 21: CNS analysis of selected cycles and surface roughness of the corresponding castings tf, f ti g i e r ot e s e n k gi ) ) ) h u s l u i h u s li s t u e l t m r ] 1 %( ] 1 ( ] 1 ( ] ar n et ci ar s ] e n et s ] k i y e o r f s . In C % . N % . S % . e h s w u m WITH e b g e µ b e a h c s u m f n w w w u a G [ e e e c äl G [ d äl G µ [ A g s G [ G [ G [ fr s r a fr s e e d e b e u A b d n O ad t S O r e d1 82.8 0.13 < NG < NG 150 17 4 71.5 0.13 < NG < NG 146 9 8 58.9 0.12 < NG < NG 116 8 12 48.4 0.14 < NG < NG 157 11 14 43.9 0.16 < NG < NG 16 36.3 0.14 < NG < NG 144 7 20 24.8 150 11 22 20.5 0.14 < NG < NG 24 16.9 135 13 26 14.0 0.13 < NG < NG 30 9.6 0.15 < NG < NG 145 18 (1) The abbreviation NG indicates that the measured values ​​are below the detection limit 2.3.2 Magnesium hydroxide Mg(OH)2 when inorganically bound core sand is added in subsequent cycles With magnesium hydroxide Mg(OH)2 in the form of brucite type 3 as an additive, it becomes apparent after just a few cycles that the properties of the molding material cannot be kept stable. Therefore, the bentonite content of the molding material is increased in cycles 8 and 15 (Table 22). Despite this, there is no stabilization of the molding material properties. In particular, the wet tensile strength decreases with increasing number of cycles, and this trend can only be counteracted in the short term by adding more fresh bentonite (Table 23).Similar to the addition of ColdBox core sand (test series 2.2.2), the addition of Mg(OH)2 as an additive does not result in a molding material cycle with stable molding material properties. The water requirement of the mix increases significantly, and the other molding material parameters also show instability (Table 23). The water requirement of a molding material corresponds to the water content of the molding material mix in its as-molded state (target compactability). The activated clay content and wet tensile strength show a significant decrease with increasing number of cycles. Although this can be compensated for by adding bentonite, overall the molding material cycle with stable molding material properties is not achieved. Table 22: Composition and compactability of the molding material mix in the individual cycles l. i e tl ti f d t ] a e k s f u o l t s ] n ng a a % ti s ] n vi g d n . ot ] g t r i ] e h g s s ] l e r g r ] a bt ] k y Z m r [ o nr [ a w n [ d d [ a m [ e % [ h % [ F e K s e nr G e A W s s c i e [ B a dr K W eV 0 4000 600 4.76 480 300 120 2.7 46.0 1 3800 190 9.30 19.0 13.3 50 2.7 47.0 2 3750 188 13.62 18.8 13.1 50 2.6 45.2 3 3800 190 17.73 19.0 13.3 50 3.0 44.5 4 3800 190 21.65 19.0 13.3 50 2.9 42.0 5 3800 190 25.38 19.0 13.3 50 3.2 42.9 6 3800 190 28.93 19.0 13.3 50 3.3 46.7 7 3800 190 32.32 19.0 13.3 50 3.4 43.5 8 3750 188 35.54 76.09 13.3 70 3.4 40.0 9 3750 188 38.61 26.3 13.1 60 3.4 40.5 10 3750 188 41.53 26.3 13.1 70 3.7 44.0 11 3700 185 44.32 26.3 13.1 70 3.7 45.0 12 3700 185 46.97 26.3 13.1 70 3.9 45.0 13 3750 188 49.49 26.3 13.1 70 3.7 43.0 14 3800 190 51.90 34.04 13.3 100 4.5 43.0 15 3800 190 54.19 34.04 13.3 90 4.8 44.6 16 3800 190 56.37 34.04 13.3 80 4.5 45.0 17 3800 190 58.45 34.04 13.3 80 4.5 43.0 18 3800 190 60.43 34.04 13.3 80 4.5 45.0 Table 23: Characteristic values ​​of samples taken in the respective cycles f f t r o i t t e l e k - g s t s u e lt i m r ] a h gi t i s ] o F ] k er f % e s s l ti s . g n e f ² Z ² ä e l h k m a kr c N m c h z a ] y Z e b g w f n e o t % c / * 0 / cr s ti b % [ u a G v i ur N [ 0 N [ u d e ß e i A g t s k d n 1 s k l u A ü A r a F G G0 100% 4.8 18.6 42.7 159 51.5 1 87.0 4.2 19.4 36.8 164 51.9 2 82.8 3.8 20.6 27.9 158 51.0 3 78.9 3.2 19.7 16.5 157 51.0 4 75.1 2.6 19.8 14.8 156 50.6 5 71.5 2.4 20.3 10.3 163 49.6 6 68.1 2.3 19.3 10.3 150 50.3 7 64.9 2.0 19.5 8.5 154 50.3 8 61.8 3.2 22.6 16.3 142 50.1 9 58.9 3.5 19.1 14.5 149 51.6 10 56.1 3.2 21.4 13.6 168 52.5 11 53.4 3.5 21.1 13.3 165 51.8 12 50.8 3.7 21.4 12.7 168 52.4 13 48.4 3.3 22.6 12.4 156 52.0 14 46.1 7.4 23.4 20.5 140 51.5 15 43.9 7.9 23.5 26.0 172 52.3 16 39.9 7.4 22.6 24.8 183 52.1 17 36.3 7.1 23.0 25.4 166 51.3 18 33.0 6.9 22.7 24.8 154 52.5 The analysis of selected molding material samples (Table 24) shows a slight increase in carbon content for high cycle numbers, which presumably results from the addition of bentonite; Ca bentonites are treated with carbonates during activation. The surface roughness of the castings is always acceptable, ie, good to very good.Table 24: CNS analysis of selected cycles and surface roughness of the corresponding castings f. f ti g ti n e h r ot e e h s u t s ] ) h u 1 ) 1 ) 1 u a li e ci ar s li s u e l t i m r % ( ] ( ] ( ] r t s e n e et s k e o y r f . % % % n e s ] w Z e s b g w C. N . S . hu m µ b h ] a c s ä u m µ f n e w u a G ew e w e c G [ d l fr G [ A g [ s G ä [ G [ G [ l fr s r e a e s e u e d d n b d A b THE at O S r e d1 87.0 0.18 < NG < NG 151 16 4 75.1 0.23 < NG < NG 141 11 8 61.8 0.24 < NG < NG 132 11 12 50.8 0.26 < NG < NG 154 7 14 46.1 0.30 < NG < NG 16 39.9 0.37 < NG < NG 196 28 18 33.0 0.28 < NG < NG 172 6 (1) The abbreviation NG indicates that the measured values ​​are below the detection limit 2.4 Additive Al(OH)3 when adding fresh molding material in the subsequent cycles (not according to the invention) 11 cycles (0-10) are carried out using the (https: / / www.researchdisclosure.com / database / RD705032) The first test was carried out using 100% fresh H32 mold base material from Quarzwerke. In all subsequent cycles 1 to 10, 3.7 kg of the used mold material from the previous casting was used and refreshed with 185 g of mold base material (fresh mold base material), 26 g of bentonite, and 23 g of the respective additive (Table 25). SH950 nuance-00 from Alteo was used as the aluminum hydroxide Al(OH)3 additive.Stable mold material properties were achieved (Table 26). When using fresh mold base material as an additive (see Figure 2, step (1)), good molding properties and a good to very good surface quality were achieved, which can be seen from the measured roughness of the castings. As expected, the CNS analysis after 11 cycles shows no significant carbon and nitrogen contents, since only inorganic materials were used (see Table 27). Table 25: Composition and compressibility of the mold material mixture in the individual cycles. s g n g u u n g g l u r mf ur n u n ur tl t a i e k s a ul f k f y ei i f Z s d ot e k o y t ] g o g ]i s r ei r ei h r s l e ] a ] [ d n n a s % o d g s g n o n o m gr Z s m e % bt h % m r e d n i s u m r o [ ti n i d vi i dr o gi e n i s [ [ s c i F r a e o s F ot ti s a dr v u e N n e d d s a W e V N B A W0 3700 185 4.8 322 207 130 2.4 42.1 1 3700 185 9.3 25.9 22.2 50 2.6 41.0 2 3850 193 13.6 27.0 23.1 50 2.6 39.5 3 3800 190 17.7 26.6 22.8 50 2.6 42.0 4 3800 190 21.7 26.6 22.8 50 2.7 41.5 5 3750 188 25.4 26.3 22.5 50 2.9 40.5 6 3800 190 28.9 26.6 22.8 50 3.0 42.0 7 3750 188 32.3 26.3 22.5 50 3.0 44.5 8 3700 185 35.5 25.9 22.2 50 3.1 43.0 9 3700 185 38.6 25.9 22.2 50 3.2 44.0 10 3700 185 41.5 25.9 22.2 50 3.2 44.5 Mean 2.9 42.2 Table 26: Characteristic values ​​of samples taken in the respective cycles f f ti r ot t e l e k - g i t s ] a t h g it s l i s u e l t i m r o % e s e ] ² F Z ] ² s äl h e kr k er f s . w g n fk m c N* m c h a z a y e b g e o t % c u / N0 / c N r u s ti b ß % Z f n u a G v A g [ it r d [ 0 1 [ d s k n s e k e il u A ü A r a F G G 0 85.5 8.9 18.1 47.8 154 50.5 1 79.4 6.6 19.5 49.2 194 51.5 2 73.8 7.8 17.4 40.1 165 51.5 3 68.6 7.9 18.8 48.9 177 53.5 4 63.7 8.5 17.3 49.6 202 53.1 5 59.2 8.9 18.7 48.9 175 52.2 6 55.0 9.0 18.4 49.4 201 52.3 7 51.1 8.8 19.9 49.3 223 52.5 8 47.5 8.8 21.1 52.0 216 53.2 9 44.1 8.9 19.0 52.9 222 53.5 10 41.0 8.9 20.1 50.9 231 53.2 Average 8.4 18.9 49.0 196 52.5 Table 27: CNS analysis of selected cycles and surface roughness of the corresponding castings f f ]ti g s li r ot % e s t s . w e n ) h u - u s l h n e et s u e m r ] e ] ] 1 ( i c ] ar et i e h c s u l t k i y e o r f % s . G [ w t % s . % . C w N w S % . n s ] , e w ä h s u m b l fr G ] s m Z e b g f n e u lr e e w c G µ [ ad e b e d µ [ u a A g G [ e G [ G [ e s v h G äl [ f r r s a e e d d O ti n r e u ü b e d h A l G O at S u a r0 85,5 140 10 1 79,4 140 15 2 73,8 138 10 3 68,6 138 10 4 63,7 144 10 5 59,2 144 10 6 55,0 139 15 7 51,1 162 10 8 47,5 163 16 9 44,1 145 16 10 41,0 2,4 0,07 <NG 0,02 159 14 Mittel 147 12 (1) Die Abkürzung NG zeigt an, dass die Messwerte unter der Nachweisgrenze liegen 2.5 Al(OH)3bei Zuschlag von ColdBox-Kernsand in den Folgezyklen (nicht erfindungs- gemäß) Es werden 11 Zyklen (0-10) durchgeführt unter Verwendung der in (https: / / www.researchdisclosure.com / database / RD705032) beschriebenen Hülsenmo- delleinrichtung. Die Versuchsdurchführung und Messung der Formstoff- und Gussteilei- genschaften geschieht wie in Kapitel 2.4 beschrieben, allerdings wird in den Folgezyklen anstelle von frischem Formgrundstoff ein zweiter aufbereiteter Formstoff (vgl. Fig.2, Schritt (1)) hergestellt durch Aufbereiten von nicht abgegossenen Kernen zugegeben (Mengen- anteil am hergestellten Formstoff siehe Tabelle 28), die mit Cold-Box Bindemittel herge- stellt worden waren („ColdBox-Kernsand“).Stable molding material properties were achieved (Table 29).

[0006] Table 28: Composition and compactability of the molding material mixture in the individual cycles gs s n g u u n g g n t l u k r e m i f ur n u r ur t r l a i e k s a y i s f o ei e e h r u l ff Z k o ] o g d n t s ] s g i s g i s l e g ] a b ] y t Z s m g m r e [ d d n n i a o s n m r % [ d ti nonomr n id vi i dr n i e s % [ t h c i % [ O gi F r a O s r o v n e F o r t ti e s d s s a dr e e K n e d A a W V K B W 0 3700 185 4.8 322 207 130 2.6 43.0 1 3800 190 9.3 26.6 22.8 50 2.7 41.5 2 3800 190 13.6 26.6 22.8 50 2.7 40.0 3 3850 193 17.7 27.0 23.1 50 2.9 44.5 4 3800 190 21.7 26.6 22.8 50 3.0 42.5 5 3750 188 25.4 26.3 22.5 50 3.0 39.7 6 3750 188 28.9 26.3 22.5 50 3.1 40.5 7 3750 188 32.3 26.3 22.5 50 3.1 40.5 8 3750 188 35.5 26.3 22.5 50 3.4 45.0 9 3750 188 38.6 26.3 22.5 50 3.5 45.0 10 3700 185 41.5 25.9 22.2 50 3.3 40.0 Average 3.0 42.0 Table 29: Characteristic values ​​of samples taken in the respective cycles f f r ot t- e s t s l g u e m r ] a i h s ] l t i ² F ] s l ti h e k k e of % . e y r e s g w g F e n o m Z ² ä N m l h a z r a t % D G c / * 0 c / cr s ti b ß % Z bf n u a G v N A g [ it [ 0 1 N [ u d s k s e k e il u A a F A G0 85.5 10.0 16.1 40.6 163 51.9 1 79.4 7.0 18.0 48.2 172 51.0 2 73.8 7.7 16.4 42.7 146 51.5 3 68.6 8.8 18.6 49.3 162 52.3 4 63.7 8.4 19.1 48.1 167 52.1 5 59.2 9.0 19.8 45.9 164 52.0 6 55.0 8.7 19.8 42.3 170 52.0 7 51.1 8.8 19.6 40.2 189 51.6 8 47.5 8.7 18.1 39.8 189 52.5 9 44.1 9.0 17.7 44.3 195 52.9 10 41.0 8.6 19.8 35.9 181 51.1 Average 8.6 18.4 43.3 173 51.9 The data from the CNS analysis of the molding material after 11 cycles show, particularly in comparison to the test series with new sand feed, significant carbon and nitrogen contents originating from the addition of ColdBox core sand (Table 30). Table 30: CNS analysis of selected cycles and surface roughness of the corresponding castings f f ] r ot % . ti g - e n u u a s l e s t s u e ] w e h lt m r % G [ ] ) u s li h c r i i n et s % ] % 1( ] ar et s ] e e h s k i y e o r f . t . . Z e s b g w s u C w e N w e S % n . , e h s u m w µ b c a äl u f G ] m µ f n e G lr G G e c äl G [ dr r e s e [ u a [ e [ [ A g s v G [ fr s a b u h e e d O d ti A ül b d n G Oat r S e e d h0 85,5 132 5 1 79,4 135 14 2 73,8 133 10 3 68,6 132 9 4 63,7 136 13 5 59,2 148 12 6 55,0 127 13 7 51,1 136 11 8 47,5 150 11 9 44,1 157 11 10 41,0 2,9 0,47 0,03 0,02 160 9 Mean 141 11 (1) The abbreviation NG indicates that the measured values ​​are below the detection limit 2.6 Al(OH)3with addition of inorganically bound core sand in the subsequent cycles 11 cycles (0-10) are carried out using the in (https: / / www.research- disclosure.com / database / RD705032) described sleeve model device The test procedure and measurement of the molding material and casting properties are carried out as described in Chapter 2.4, however, in the subsequent cycles, instead of fresh molding material, a second prepared molding material (see Fig. 2, step (1)) is added, produced by preparing uncast cores (for the proportion of the produced molding material, see Table 31), which had been produced with inorganic binder (water glass) ("IOB core sand").This is therefore an inorganic molding material cycle with regard to all binders used. Stable molding material properties were achieved (Table 32). Table 31: Composition and compactability of the molding material mixtures in the individual cycles s s. u u l lk ] i e t t tl i e s a f y Z g [ n a ] ti a v r h e kr u l f k ot m e ] d g n d % n . n w ot ] i g ti e d ] g s s ]l gr ] a bt ] y Z s [ a m a e n [ d [ a m [ e % [ h c % [r g io r s nr s n G e B A W s s i d F e hr e r e [ a r e o K v K W V 0 3700 185 4.8 322 207 130 2.5 43.0 1 3850 193 9.3 27.0 23.1 50 2.5 42.0 2 3800 190 13.6 26.6 22.8 50 2.6 40.0 3 3800 190 17.7 26.6 22.8 50 2.8 42.0 4 3800 190 21.7 26.6 22.8 50 2.9 41.5 5 3750 188 25.4 26.3 22.5 50 3.0 43.2 6 3750 188 28.9 26.3 22.5 50 3.0 40.5 7 3750 188 32.3 26.3 22.5 50 3.1 43.5 8 3750 188 35.5 26.3 22.5 50 3.3 42.5 9 3700 185 38.6 25.9 22.2 50 3.3 43.0 10 3700 185 41.5 25.9 22.2 50 3.3 45.0 Average 2.9 42.6 Table 32: Characteristic values ​​of samples taken in the respective cycles l f h f a r ot t z s e s t s l u e ma ti r ] h ] F ] e k ti e l t i o k y er f % s . e w g n ] % F ² Z ² g i kr D m c ] Z e b g n e o t [ G / N* m c s s a b N 0 / % 0 N äl ß [ f u a G [ v it [ 1 [ h e i A g s k cr l u A u F A d s a G 0 85,5 8,6 16,5 38,1 144 52,0 1 79,4 6,9 16,7 42,8 151 51,7 2 73,86,7 19,8 48,0 152 51,03 68,6 8,8 19,5 49,1 162 52,0 4 63,7 9,2 20,4 48,9 177 52,0 5 59,2 8,9 19,6 43,4 172 53,3 6 55,0 9,1 21,2 48,8 174 51,7 7 51,1 9,4 20,5 48,2 188 52,5 8 47,5 8,9 20,6 44,4 196 52,5 9 44,19.0 18.1 48.8 200 52.710 41.0 9.1 19.0 49.2 194 52.5 Average 8.6 19.3 46.3 174 52.2 The molding material analyses (Table 33) show that there is no significant accumulation of carbon, nitrogen, or sulfur in the molding material; C-containing (carbon-containing) components from the inorganic binder (such as surfactants) are of minor importance. The low C (carbon) load is one of the major advantages of this inorganic molding material cycle, as only very low emissions are to be expected (see below). Despite the lower carbon content, the surface roughness obtained (Table 33) is comparable to that of the tests with the addition of coldbox core sand (test series 2.5). Table 33: CNS analysis of selected cycles and surface roughness of the corresponding castings t i f f ] % ti g e r ot . e n k e h s u gi u s s t s m] w e ) 1 ) ) u l ( 1 ( 1 ( ar i h et ci e ar li et u e l t i r e of % . G [ t ] % ] % ] % n e s s ] w n e h s s ] k y r Z e s b g w e s u C. f n w N . w S . w h c u m µ [ b a c ä u m µ [ u a G lr e e e g [ e G G G äl G d f r l r s a fr G e s A sv u h [ [ [ e e d e A ül b d n b d G O at S O r e d 0 85,5 134 13 1 79,4 131 11 2 73,8 123 10 3 68,6 132 12 4 63,7 137 12 5 59,2 144 9 6 55,0 138 12 7 51,1 136 10 8 47,5 147 8 9 44,1 148 11 10 41,02,3 0,08 0,01 <NG 144 8Mittel 138 11 (1) Die Abkürzung NG zeigt an, dass die Messwerte unter der Nachweisgrenze liegen 3. Formstoffkreislauf mit sukzessiver Verringerung des Kohlenstoffgehalts im Formstoff Diese Versuche haben das Ziel, eine bestimmte Menge aufbereiteten Formstoff mehrmals abzugießen und wieder aufzubereiten, insbesondere mit sukzessiver Verringerung des Kohlenstoffgehalts im Formstoff. Wie in der industriellen Gießerei üblich wird der Formstoff dabei in einem Kreislauf geführt. Bei jeder Aufbereitung des Formstoffes werden Additive zugeführt, die sich mit jedem Zyklus anreichern. Komponenten, die im Ausgangsformstoff vorhanden sind, aber nicht mehr zugegeben werden, verringern sich, d.h. die Anteile der Komponenten, die in den Folgezyklen nicht mehr zugegeben werden, verringern sich. Die Gesamtmenge des Formstoffs ist konstant und beträgt rund 1.200 kg. Pro Zyklus werden vier Formen entsprechend der Rippenmodelleinrichtung wie in (https: / / www.researchdisclosure.com / database / RD705032) and cast. To illustrate the test procedure, reference is made to the molding material cycle in Fig. 4. The cycles of the molding material cycle include the following steps: Production of the molding material (step (1), first cycle) In the first cycle, processed molding material (starting molding material) from the molding material cycle of a brake disc foundry is used. (see point 0.2 above) The processed molding material is conveyed from a big bag into a hopper in front of the Eirich mixer (Eirich intensive mixer R09 with a capacity of 150 liters, max. 240 kg, batch operation under standard atmosphere) using a big bag unloading station and two conveyor belts. The previously weighed additives (aggregates) bentonite, base mold material or core molding material as well as the additive are added to the hopper discharge belt. Al(OH)3 of type SH950 (SH950 nuance -00, Alteo) is used as an additive. During each manufacturing process (step (1), seeFigure 4) of a molding material, additives are added which increase with each cycle. By discharging a portion of the poured molding material in step (5) or in step (1) of the next cycle (see Figure 4), the proportion of components that are present in the initial molding material but are no longer added is reduced. The molding material is drawn from the bunker and transported to the mixer together with the additives. The mixing process starts, water is automatically dosed and, after the mixing process is complete, the finished molding material is emptied from the mixer into a transport container. The transport container is transported to the molding system. The mixer program is selected between a mixing process without intermediate stop (Table 35) and a mixing process with intermediate stop (Table 34) depending on the situation (depending on the water content of the mix) and the desired compaction is set to 40% + / - 5% by controlling the water content.The desired compaction is achieved by checking the compactability. Compactability varies with the water content of the molding material. The water content was determined for each mix. Since the amount of water required to achieve the target compactability is unknown, the intermediate stop in the mixing process makes it easier to determine the required water quantity, and subsequent mixes can be produced without an intermediate stop. Table 34: Mixing process with an intermediate stop. Program step in the mixing program. Rotation of agitator. Rotation of the Eirich mixer container m / s. m / s Zeit s0Home position +6.00 1.001 Material addition +6.00 0.802 Mixing +6.00 0.80 15 3Water addition +6.00 1.004 Mixing +12.00 1.30 70 5Sampling 6 Mixing +12.00 1.30 10 7Water addition +12.00 1.2012 Mixing +12.00 1.30 45 13 Mixing finished +6.00 1.0014 Empty mixer +6.00 1.00 40 Table 35: Mixing sequence without intermediate stop Program step in the mixing program Rotation of agitator / Rotation of container / Time / of the Eirich mixer m / sm / ss 0Home position +6.00 1.001 Material addition +6.00 0.802 Mixing +6.00 0.80 15 3Water addition +6.00 1.004 Mixing +12.00 1.30 90 13 Mixing finished +6.00 1.0014 Emptying the mixer +6.00 1.00 40 Making the mold (step (2) in all cycles) For this purpose, first a partial volume of the lower box of the mold is filled with a layer of sieved molding material from the transport container; so much molding material is sieved that the contour of the rib model is no longer visible (this corresponds to a height of 80 mm in the lower box and 50 mm in the upper box).The remaining volume of the lower box is then filled with unscreened molding material. The screen has a mesh size of 2 mm. The lower box (i.e., the molding material in the lower box) is compacted in the HWS HSP-1D molding system using a Seiatsu airflow compression molding process with the specified parameters (Table 36, mold box size of 700 x 500 x 200 / 200 mm, pattern plate size of 650 x 450 x 30 mm). The time during which an airflow is passed through the molding material in the mold box to fluidize it is referred to as the Seiatsu time. The Seiatsu time can be set independently for the cope and lower boxes. The molding material is then pressed.Table 36: Compaction parameters Lower box Pressing pressure: 90 N / cm² Upper box Pressing pressure: 80 N / cm² Lower box Pressing time: 2,000 s Upper box Pressing time: 2,000 s Lower box SEIATSU time: 0.50 s Upper box SEIATSU time: 0.50 s The lower box is pulled off by hand and transported to the loading station by a crane. The upper box is filled, compacted, pulled off and transported in the same way. A previously manufactured core (step (1a), see Fig. 4) is inserted into the lower box (step (2a), see Fig. 4). The mold is added, clamped and transported to the casting station. Pouring (step (3) in all cycles) The mold is poured with liquid metal of the alloy GJL 250 at 1450 °C using a pouring ladle in a support iron with one-sided shears. The next molds are manufactured (step (2), (2a)) and cast. The cast mold is left to stand for 4 hours before separation. During this time, the casting cools and the mold material heats up.Separation (step (4) in all cycles) The upper and lower boxes are opened. The casting and the poured mold material are separated. In the three mold material cycles that were investigated, the core sand is handled differently: 1. In test series A, in which new sand is used as the added mold material, a core bonded with CO2-hardened water glass (see point 0.2 above) is used, which does not disintegrate during separation and is completely discharged at this point in the cycle. 2. In test series B, in which ColdBox cores are used, the core disintegrates completely in the middle and can no longer be separated from the mold material. The core marks do not disintegrate and cannot be easily crushed. Therefore, the core marks are discharged at this point in the cycle. 3. In test series C, in which inorganically bound (binder Cordis 9477 / Anorgit 9476, see point 0.2) If cores were used, they only disintegrate in the surface layer but can be easily crushed by hand. Therefore, the IOB core sand is not removed. Preparation (step (5) in all cycles) The molding material is spread out on the floor and molding material lumps are crushed using a shovel. The metal residues are removed. The molding material lies on the hall floor for at least 3 hours to cool. After cooling, the molding material is shoveled back into a big bag. Production of the molding material (step (1) in the 2nd and each subsequent cycle) A new molding material is produced by refreshing the processed molding material from the previous cycle (first processed molding material) by adding bentonite, water, additive (as defined above) and fresh molding base material (new sand, test series A) or a second processed molding material produced by processing cores (test series B and C, for details see below).For the mixing process, see the information on step (1) of the first cycle above. The increase in the quantity of molding material due to additions in the mixer, i.e. the increase in the quantity of molding material resulting from the additive defined above, is regulated by removing the same amount of ready-mixed molding material in each cycle. Each time the molding material is produced (step (1)), additives are added which increase with each cycle. By discharging a portion of the cast molding material, the proportion of components that are present in the initial molding material but are no longer added in subsequent cycles is reduced. 3.1 Test series with addition of fresh molding base material (new sand) in step (1) (Test series A, not according to the invention) When producing the mold (step (2) above), water glass-bonded cores are used which do not disintegrate after casting (see point 0.2 above) and are removed in step (4) as described above.In a test series with 30 cycles (A1-A30, see Table 37), the prepared molding material from the previous cycle (first prepared molding material) is refreshed in each subsequent cycle with Grudzen Laz.0.20 / 0.315 / 0.40 (coarse quartz sand, class 1K) molding material from Quarzwerke. Table 37: Composition and compactability of the molding material mixture in the individual cycles. r 1 ( ff ti o ] l n ] ] vi t ] r l e ) 2 ) ( 3 ( ti e t f ] t i ot li i i s ] tl e k s u r l et f ot li e e s e b d t n n e e t d e n d t n s a lie a h r a k et i y s er s t n a n g u WITH r E e b m r A - A . B A - e A -. Wt n e g bt f r A u o - . u Z g w e e b . In b e A a w b - . r e h c i d a F w e m r a G [ o g e g e a g w e s s r F G [ u Z G [ u Z G [u Z G [ a e W VA-1 90,2% 6,4% 1,2% 0,5% 1,6% 3,0% 41,3% A-2 90,0% 6,4% 1,2% 0,5% 1,8% 3,1% 40,7% A-3 90,1% 6,4% 1,2% 0,5% 1,7% 2,9% 42,3% A-4 90,2% 6,4% 1,2% 0,5% 1,6% 3,1% 41,5% A-5 90,2% 6,4% 1,2% 0,5% 1,6% 3,1% 41,9% A-6 90,4% 6,5% 1,2% 0,5% 1,3% 3,1% 40,3% A-7 90,2% 6,4% 1,2% 0,5% 1,6% 3,1% 41,4% A-8 90,1% 6,4% 1,2% 0,5% 1,7% 3,3% 41,7% A-9 90,1% 6,4% 1,2% 0,5% 1,7% 3,3% 40,9% A-10 90,2% 6,4% 1,1% 0,5% 1,8% 3,1% 41,8% A-11 90,3% 6,4% 1,1% 0,5% 1,6% 3,2% 39,9% A-12 90,3% 6,5% 1,1% 0,5% 1,6% 3,4% 42,3% A-13 90,5% 6,5% 1,1% 0,5% 1,4% 3,3% 42,5% A-14 90,4% 6,5% 1,1% 0,5% 1,6% 3,3% 42,2% A-15 90,5% 6,5% 1,1% 0,5% 1,4% 3,3% 43,3% A-16 90,8% 6,5% 1,1% 0,5% 1,1% 3,3% 41,8% A-17 90,2% 6,4% 1,1% 0,5% 1,7% 3,3% 41,3% A-18 90,3% 6,4% 1,1% 0,5% 1,7% 3,3% 39,4% A-19 89,8% 6,4% 1,1% 0,5% 2,2% 3,3% 41,0% A-20 90,2% 6,4% 1,1% 0,5% 1,7% 3,2% 42,8% A-21 90,8% 6,5% 1,1% 0,5% 1,1% 3,4% 43,6% A-22 90,2% 6,4% 1,1% 0,5% 1,7% 3,3% 40,0% A-23 90,1% 6,4% 1,0% 0,5% 1,9% 3,3% 39,5% A-24 90,0% 6,4% 1,0% 0,5% 2,0% 3,4% 39,5% A-25 89.8% 6.4% 1.0% 0.5% 2.3% 3.3% 39.5% A-26 89.7% 6.4% 1.0% 0.5% 2.4% 3.6% 38.9% A-27 90.1% 6.4% 1.0% 0.5% 2.0% 3.4% 38.7% A-28 90.0% 6.4% 1.0% 0.5% 2.0% 3.3% 43.0% A-29 89.9% 6.4% 1.0% 0.5% 2.1% 3.1% 37.8% A-30 90.1% 6.4% 1.0% 0.5% 1.9% 3.4% 38.1% Average 90.2% 6.4% 1.1% 0.5% 1.7% 3.2% 41.0% (1) “First recycled molding material” refers to the amount of molding material from the previous cycle that was reused after recycling (2) Addition of water (3) Measured water content of the mixture Table 38: Characteristic values ​​of samples taken in the respective cycles to determine the molding material properties t, f f t i r o i e t t e k e g - s t s ] l mi l k e g i t g i t t a h i t ] s ] s s l i e u e l ti r of n e g ] s ef ² e m f g ² m äl h k h a r k e y r e s g A - . n o k t % [ c c / u z c / c z a r s ti b Z bf n w u a e v it ur A g d N [ s s N u a [ d s G s e k ß e il u [ k A n ü r N* a F A G 0 0 G1A-1 90% 5.5% 23.0 42.2 146 71% A-2 81% 5.7% 21.1 36.2 135 69% A-3 73% 5.9% 22.6 35.2 134 67% A-4 66% 6.2% 20.9 32.5 135 77% A-5 60% 6.2% 21.1 39.1 151 73% A-6 54% 6.5% 21.6 43.4 134 70% A-7 49% 6.6% 22.3 33.0 123 71% A-8 44% 6.7% 21.3 36.2 117 63% A-9 39% 6.9% 22.1 38.5 115 63% A-10 36% 6.8% 20.1 38.1 145 59% A-11 32% 7.1% 21.7 36.6 128 63% A-12 29% 6.9% 21.2 37.8 124 59% A-13 26% 6.2% 21.2 41.5 143 56% A-14 24% 6.6% 21.1 35.8 126 63% A-15 22% 6.8% 21.2 36.2 131 55% A-16 20% 6.8% 22.2 46.7 137 60% A-17 18% 6.8% 20.6 37.5 127 51% A-18 16% 7.0% 21.5 33.4 115 68% A-19 14% 7.0% 21.1 33.1 126 63% A-20 13% 7.0% 20.6 35.6 149 57% A-21 12% 6.4% 21.9 38.6 154 53% A-22 11% 6.4% 21.4 36.1 136 60% A-23 9% 6.3% 19.3 35.6 138 57% A-24 9% 6.5% 21.5 36.3 119 64% A-25 9% 6.5% 20.5 34.1 129 63% A-26 8% 6.8% 19.8 33.0 126 52% A-27 7% 6.8% 21.2 34.6 123 57% A-28 6% 6.5% 18.7 30.9 144 53% A-29 6% 6.9% 20.4 35.9 160 54% A-30 5% 6.8% 22.0 33.1 130 50% Average 6.6% 21.2 36.5 133 61,4%Table 39: Analysis of samples from individual cycles t, l a e d ß ar t h e ö gs l i s s ] t ] t ] t ] g rl ti et mu u l l l l ff ] g l n h e n ] k r y e % v . a % a % a % % w h e . w h e . w h r ] a k a m e . o % w t s . w o m Z- gi nr 5. Z h ül e G - e G - e G- e m e K e m [ S F ß äo k 2 1 w , e G G [ C G [ N G [ S G [ m G äl [ r el A m h ni G e 0 < [ h c tt i ci F S M el G A-1 3,30 2,18 0,04 0,04 10,6 0,31 51 60,2 2,1 A-5 2,80 1,36 0,02 0,02 10,3 0,31 51 59,1 2,7 A-10 2,52 1,05 0,01 0,01 10,3 0,31 51 58,7 2,8 A-15 2,29 0,82 0,01 0,01 10,6 0,30 52 59,2 3,3 A-20 0,58 0 0 10,5 0,31 52 57,4 4,0 A-23 2,07 A-25 0,45 0 0 11,0 0,31 52 56,9 4,4 A-27 2,01 A-29 1,93A-30 0.31 0 0 10.9 0.31 52 58.6 3.9As expected, a gradual decrease in the loss on ignition of the samples can be observed, since with increasing cycle numbers, less organic material is present in the molding material. This is also demonstrated by the gradual decrease in the carbon, nitrogen, and sulfur contents (Table 39). The molding material properties remain essentially unchanged (Table 38). Despite the decreasing carbon content, no casting defects are observed, and the surface roughness of the castings does not change significantly due to the reduction in the carbon content (Table 40). Table 40: Surface roughness of castings produced during test series A Cycle A-1 A-5 A-10 A-15 A-20 A-23 A-27 A-30 Mean Proportion of the initial molding material [Wt.%] 90% 60% 36% 22% 13% 9% 7% 5% Surface roughness of the G ussteils [µm]249 250 254 277 253 253 278 290 263Standard deviation of the surface roughness of the casting [µm] 34 29 19 30 29 34 8 26 26 3.2 Test series with the addition of organically bound core sand (test series B, not according to the invention) During mold production (see step (2)), cold box cores (see point 0.2 above) are inserted, which completely disintegrate in the middle and can no longer be separated from the molding material. In this test series with 30 cycles (B1-B30, see Table 41), starting from the above-described prepared starting molding material from a brake disc foundry, a second prepared molding material (see Fig. 4) was added, produced by preparing cores that had been produced with cold box binder; ieIn each subsequent cycle, the prepared molding material from the previous cycle (first prepared molding material) is refreshed with a second prepared molding material produced by preparing cores that had been produced with cold-box binder. Table 41: Composition and compactability of the molding material mixture in the individual cycles. - r 1 e ( x t o ]l i n o ]l vi t r ) ) 3 t i ]l e s 2 ( ( t i e s u r t l e f t f ] ot li B e dl d i n et t n i e et d i d et s a ]l i l ke a h r a k et i y s Z r er s t E e b m n o a A Cs n n A. B n A . A n e A. W t e n e bt A g f r r h u o -. e r a F w b e a e w e K e b w b w b . e c i G a e a G g e a g w e s s dr G g [ g [ [ u Z u Z u Z G [ u Z G [ a e W VB-1 91,8% 4,4% 1,1% 0,5% 2,2% 2,8% 42,2% B-2 92,0% 4,4% 1,1% 0,5% 1,9% 3,0% 38,5% B-3 91,6% 4,8% 1,1% 0,5% 1,9% 3,0% 40,6% B-4 91,6% 4,8% 1,1% 0,5% 2,0% 3,1% 42,1% B-5 91,8% 4,8% 1,1% 0,5% 1,8% 3,0% 39,4% B-6 91,7% 4,8% 1,1% 0,5% 1,9% 2,9% 40,0% B-7 91,5% 4,8% 1,1% 0,5% 2,1% 3,1% 43,0% B-8 91,5% 4,8% 1,1% 0,5% 2,1% 3,0% 41,7% B-9 91,5% 4,8% 1,1% 0,5% 2,1% 3,0% 40,5% B-10 91,5% 4,8% 1,1% 0,5% 2,1% 3,1% 40,5% B-11 91,4% 4,8% 1,1% 0,5% 2,2% 3,1% 39,5% B-12 91,5% 4,8% 1,1% 0,5% 2,1% 2,9% 39,0% B-13 91,4% 4,8% 1,1% 0,5% 2,2% 3,1% 39,6% B-14 91,4% 4,8% 1,1% 0,5% 2,2% 3,2% 39,7% B-15 91,3% 4,8% 1,1% 0,5% 2,3% 3,3% 41,7% B-16 91,5% 4,8% 1,1% 0,5% 2,1% 3,2% 40,0% B-17 91,3% 4,8% 1,1% 0,5% 2,3% 3,3% 41,2% B-18 91,4% 4,8% 1,1% 0,5% 2,2% 3,1% 40,0% B-19 91,0% 4,8% 1,1% 0,5% 2,6% 3,0% 40,1% B-20 91,4% 4,8% 1,1% 0,5% 2,3% 3,3% 39,1% B-21 91,2% 4,8% 1,1% 0,5% 2,4% 3,5% 41,5% B-22 91,3% 4,8% 1,1% 0,5% 2,3% 3,2% 39,1% B-23 91,4% 4,8% 1,1% 0,5% 2,2% 3,3% 40,6% B-24 91,3% 4,8% 1,1% 0,5% 2,3% 3,2% 41,8% B-25 91.5% 4.8% 1.1% 0.5% 2.1% 3.4% 40.7% B-26 91.5% 4.8% 1.1% 0.5% 2.1% 3.3% 40.4% B-27 91.6% 4.8% 1.1% 0.5% 2.0% 3.2% 39.2% B-28 91.5% 4.8% 1.1% 0.5% 2.1% 3.1% 40.2% B-29 90.9% 4.8% 1.1% 0.5% 2.7% 3.3% 41.7% B-30 91.2% 4.8% 1.1% 0.5% 2.4% 3.3% 41.5% Average 91.5% 4.8% 1.1% 0.5% 2.2% 3.1% 40.5% (1) “First recycled molding material” refers to the amount of molding material from the previous cycle that was reused after recycling (2) Addition of water (3) Measured water content of the mixture Table 42: Characteristic values ​​of samples taken in the respective cycles to determine the molding material properties f, f t r o i t t e e s ]l i l a k - g g i s ti s t u e l t i m r e o t h i e ts ] ² F Z ] ² s ä l e l h kr k er f n s A g n ] e f k m c N m c h a c z a y Z e b g . f n w o t % [ c u / * u a e v it r N [ 0 / 0 N [ r u s t d i b e ß e i A g s G u [ k d A n 1 s k l ü r a F A G GB-1 92% 5.2% 22.5 38.2 147 53% B-2 85% 5.6% 21.8 33.0 133 53% B-3 77% 5.6% 22.1 30.2 130 65% B-4 71% 5.6% 21.4 30.5 127 63% B-5 65% 5.8% 21.3 31.7 136 63% B-6 60% 5.7% 21.4 33.3 135 62% B-7 54% 5.6% 19.8 33.7 139 57% B-8 50% 5.8% 20.5 31.0 155 67% B-9 46% 5.9% 20.4 31.7 142 54% B-10 42% 5.6% 20.6 37.2 143 58% B-11 38% 5.8% 20.1 31.7 127 59% B-12 35% 6.0% 20.9 32.2 130 50% B-13 32% 6.1% 20.4 30.4 126 55% B-14 29% 6.1% 18.9 33.7 163 51% B-15 27% 6.1% 19.0 34.0 160 52% B-16 24% 6.0% 19.7 32.4 154 50% B-17 22% 6.1% 19.2 34.1 136 57% B-18 20% 6.1% 18.3 34.4 172 61% B-19 18% 5.7% 17.8 31.8 152 61% B-20 17% 5.6% 19.0 32.3 133 61% B-21 15% 5.7% 18.3 31.7 144 52% B-22 14% 6.3% 18.8 32.7 169 53% B-23 13% 6.2% 18.9 31.5 159 55% B-24 12% 6.5% 18.3 31.9 177 57% B-25 11% 6.2% 18.8 32.5 135 58% B-26 10% 6.3% 18.5 34.5 141 53% B-27 9% 6.4% 18.2 31.5 152 60% B-28 8% 6.1% 18.6 30.1 141 60% B-29 7% 6.2% 18.3 33.0 137 55% B-30 7% 5.5% 19.8 30.9 125 62% Medium 5.9% 19.7 32.6 144 57,3%Table 43: Analysis of molding material samples from selected cycles f, f r o e t - e e ß s ti l i s t s ]l e i t t m r et s u l ] tl a ] tl a ] f tl a ] f o ö t s ] r g l e et n h k g n m m ] ul k i y e o r f n r s A % . e w h % e . w h % e . w h e % . % w m . w r o ] a m Z i -ß d a a nr 5 % w Z e b g f n w v u a g e h ü e G Ge Ge G l G [ - C G [ - N G [ G- e S G m [ äl e K m h G e S ä r c [ r [ F m e h g o k 2 1, e G l A ci ni e 0 < [ A s u [ S tt A i e M l F GB-1 92% 3.60 2.41 0.04 0 10.9 0.3 53 59.2 3.08 B-4 71% 3.33 1.91 0.04 0.03 10.8 0.29 54 60.1 3.91 B-8 50% 3.03 1.59 0.05 0.03 11.0 0.29 54 58.0 4.97 B-12 35% 2.76 1.25 0.04 0.01 11.0 0.29 54 57.9 5.31 B-16 24% 2.74 1.18 0.05 0.01 10.8 0.3 52 57.3 4.82 B-20 17% 2.56 0.95 0.04 0.01 10.9 0.31 53 56.5 4.95 B-24 12% 2.46 0.75 0.04 0.01 10.8 0.32 51 56.7 4.12 B-28 8% 2.29 0.71 0.04 0.01 10.9 0.31 52 56.0 4.34 B-30 7% 2.32 0.65 0.04 0.01 10.8 0.31 51 56.2 4.22 The molding material analysis (Table 43) shows that the loss on ignition of the molding material decreases with increasing number of cycles. At the same time, the carbon (C), sulfur, and nitrogen (N) content decreases, with the C and N content approaching limits determined by the addition of cold-box bonded core sand. The molding material properties remain essentially unchanged (Table 42). The surface roughness of the castings is also determined in this series of tests (Table 44).It is observed that good surfaces are obtained despite the decreasing carbon content in the molding material. No casting defects can be observed. Table 44: Surface roughness of castings produced during test series B Cycle B-1 B-4 B-6 B-8 B-12 B-16 B-20 B-24 B-30 Mean Proportion of initial mold material 92% 71% 60% 50% 35% 24% 17% 12% 7% Surface roughness 248 231 287 296 266 282 289 309 276 276 of the casting [µm] Standard deviation 31 40 41 51 38 54 47 56 29 43 of the surface roughness of the casting [µm] 3.3 Test series with addition of inorganically bound core sand (Test series C) When producing the mold (see step (2) above), Inorganically bound cores (binder Cordis 9477 / Anorgit 9476, see point 0.2 above) were used, which only disintegrate in the surface layer but can be easily crushed by hand. In this test series with 30 cycles (C1-C30, seeTable 45) a second processed molding material (cf. Fig.4) produced by processing cores that had been produced with water glass binder (Anorgit / Cordis system) was added to the above-described processed starting molding material from a brake disc foundry (point 0.2); ie in each further cycle the processed molding material from the previous cycle (first processed molding material) is refreshed with a second processed molding material produced by processing cores that had been produced with water glass binder (Anorgit / Cordis system). Table 45: Composition and compressibility of the molding material mixture in the individual cycles r. ) ti ) e n vi r e ) 3 ti s t f1 f ( ] ] l l i d i e u r t ot ] l n i e t ti d ] l i e s 2 ( ( t s ]l t e i l a kr l e et k t i ot e e y s e b n a r s t n a s n A e B n d A A n a A W et h a n e bt Z r HAVE BEEN e b m f r u o A. g w u nr . Z e w e e . b w e have been b . e a w A g have been b r h a . e s c i d a F e K G G [ [ a g u G [ g Z u ZG [ g w u e s Z G [ a r e W VC-1 91,6% 4,8% 1,1% 0,5% 2,0% 2,7% 42,2% C-2 91,6% 4,5% 1,1% 0,5% 2,3% 3,0% 38,5% C-3 91,6% 4,5% 1,1% 0,5% 2,3% 3,1% 40,6% C-4 91,7% 4,5% 1,1% 0,5% 2,2% 2,9% 42,1% C-5 91,8% 4,5% 1,1% 0,5% 2,1% 3,1% 39,4% C-6 91,8% 4,5% 1,1% 0,5% 2,1% 3,2% 40,0% C-7 91,6% 4,5% 1,1% 0,5% 2,3% 3,3% 43,0% C-8 90,7% 4,5% 2,0% 0,5% 2,4% 3,5% 41,7% C-9 91,6% 4,5% 1,1% 0,5% 2,2% 3,3% 40,5% C-10 91,3% 4,5% 1,1% 0,5% 2,5% 3,5% 41,7% C-11 91,5% 4,5% 1,1% 0,5% 2,4% 3,1% 38,9% C-12 90,9% 4,5% 1,6% 0,5% 2,5% 3,6% 40,6% C-13 91,5% 4,5% 1,1% 0,5% 2,3% 3,4% 41,8% C-14 91,5% 4,5% 1,1% 0,5% 2,3% 3,6% 40,2% C-15 91,6% 4,5% 1,1% 0,5% 2,2% 3,3% 39,8% C-16 91,5% 4,5% 1,1% 0,5% 2,3% 3,4% 40,2% C-17 91,5% 4,5% 1,1% 0,5% 2,4% 3,6% 41,3% C-18 91,6% 4,5% 1,1% 0,5% 2,2% 3,4% 39,4% C-19 91,4% 4,5% 1,1% 0,5% 2,5% 3,6% 42,2% C-20 91,6% 4,5% 1,1% 0,5% 2,2% 3,7% 39,8% C-21 92,8% 4,6% 0,0% 0,5% 2,1% 3,3% 39,7% C-22 91,8% 4,5% 1,1% 0,5% 2,1% 3,4% 39,4% C-23 91,6% 4,5% 1,1% 0,5% 2,2% 3,1% 39,3% C-24 91,6% 4,5% 1,1% 0,5% 2,2% 3,4% 41,6% C-25 91.6% 4.5% 1.1% 0.5% 2.2% 3.4% 39.4% C-26 91.6% 4.5% 1.1% 0.5% 2.1% 3.3% 40.0% C-27 91.6% 4.5% 1.1% 0.5% 2.2% 3.6% 40.4% C-28 91.6% 4.5% 1.1% 0.5% 2.2% 3.3% 39.5% C-29 91.6% 4.5% 1.1% 0.5% 2.4% 3.6% 42.0% C-30 91.5% 4.5% 1.1% 0.5% 2.2% 3.3% 41.7% Average 91.6% 4.5% 1.1% 0.5% 2.3% 3.3% 40.6% (1) “First recycled molding material” refers to the amount of molding material from the previous cycle that was reused after recycling (2) Addition of water (3) Measured water content of the mixture Table 46: Characteristic values ​​of samples taken in the respective cycles to determine the molding material properties f, f t i r ot e t s ] l i tl e a k - gi g t i s l s u e l t m r et h e s e ] ²F Z ] ² s äl h a k i e o r f n s A g n ] f k m c N m c h z y Z e b g . f n w o t % [ c u / * u a e v r N 0 / cr u s ti G it d [ 0 1 N [ d s e k A g s u [ k A n ü r a A G GC-1 92% 5.1% 21.36 33.6 142 C-2 84% 5.1% 21.56 33.4 129 C-3 77% 5.5% 21.48 28.8 117 C-4 71% 5.5% 20.49 34.5 145 C-5 65% 5.5% 20.39 32.3 139 C-6 59% 5.6% 19.62 29.2 119 C-7 54% 5.4% 19.43 29.2 117 C-8 49% 5.9% 19.78 33.9 119 C-9 45% 6.1% 19.46 34.1 154 C-10 41% 6.0% 19.57 30.1 108 C-11 38% 6.0% 18.84 35.5 175 C-12 34% 6.0% 20.42 32.6 111 C-13 31% 6.2% 19.72 33.2 142 C-14 29% 5.9% 19.84 31.2 125 C-15 26% 6.0% 19.89 29.2 126 C-16 24% 6.1% 19.7 34.7 135 C-17 22% 6.1% 19.63 30.9 123 C-18 20% 6.2% 20.32 28.7 127 C-19 18% 5.9% 19.97 33.5 142 C-20 17% 5.7% 19.75 31.3 113 C-21 16% 5.2% 18.37 31.6 139 C-22 14% 5.3% 19.08 27.3 121 C-23 13% 5.3% 18.4 26.3 150 C-24 12% 5.8% 19.78 34.4 152 C-25 11% 6.6% 19.04 31.1 146 C-26 10% 6.7% 18.91 32.3 172 C-27 9% 6.5% 20.4 30.3 111 C-28 9% 6.4% 19.47 34.3 152 C-29 8% 6.6% 20.22 31.1 115 C-30 7% 6.4% 18.94 34.7 167 Average 5.9% 19.8 30.0 134Table 47: Analysis of samples from selected cycles e ef ß ti e li s r t f ]l i t s ] t ] t ] t ] f o ö ] rlk and m]l et f o et u l l a l a l a t s g n ] h gi n u e k t i t n r % . h % . h % . h % . % . r a ß a m% . y s Z r er s E e b m A e f r . v h w e e G w e e G w e e G w e m m w e o K m Z m - S ä m nr o 5 2 w e u o w F eü G - G - G - G äl G e [ F h k 1, G G l G [ C [ N [ S [ h [ r el A ci ni 0 < [ a [ c S tt i el e G F MC-1 92% 3.49 1.82 0.03 0.02 10.9 0.3 52 59.7 2.84 C-4 71% 3.01 1.63 0.03 0.02 10.8 0.31 52 57.5 3.78 C-8 49% 2.84 1.28 0.02 0.01 12.17 0.29 56 56.4 5.49 C-12 34% 2.53 1.07 0.02 0.02 11.92 0.3 54 55.4 5.2 C-16 24% 2.33 0.62 0.01 0.01 11.63 0.29 55 56.9 5.44 C-20 17% 2.17 0.52 0 0.01 12.14 0.29 56 54.8 6.08 C-24 12% 2.05 0.45 0 0 11.78 0.3 55 54.8 5.27 C-27 9% 1.79 0.4 0 0 11.22 0.31 53 55.6 4.5 C-30 7% 1.91 0.38 0 0 10.83 0.31 52 55.1 4.25 The tests clearly show the successive decrease in the loss on ignition and the contents of carbon, nitrogen and sulfur with increasing exchange of the molding material (Table 47). The mold material properties remain essentially unchanged (Table 46). Despite the decreasing carbon content, no casting defects were observed, and the surface roughness of the castings did not change due to the reduction in carbon content (Table 48).Table 48: Surface roughness of castings produced during the test series Cycle C-1 C-6 C-11 C-16 C-19 C-23 C-24 C-25 C-27 C-30 Mean Percentage of the initial molding material 92% 59% 38% 24% 18% 13% 12% 11% 9% 7% [wt.%] Surface roughness of the casting 297 280 310 305 341 293 288 296 256 289 295 [µm] Standard deviation of the surface roughness 41 28 62 60 52 41 40 38 35 47 44 of the casting [µm] 3.4 Landfill class of the processed molding material From all three In a series of tests, the processed molding material is examined after the 30th cycle (A-30, B-30, or C-30), and the obtained values ​​are compared with those of the original molding material (Table 49; the abbreviation NG indicates that the measured values ​​are below the detection limit). The following was determined: According to the German Ordinance on Landfills and Long-Term Storage (Deponieverordnung) of July 4, 2019,In 2020, the processed molding material (starting sand) is assigned to landfill class II due to its loss on ignition, TOC value (Total Organic Carbon), and phenol index. The processed molding material from test series B only has a TOC value that is slightly too high for classification in landfill class I and is therefore assigned to landfill class II, although a further reduction in the TOC value is possible through continued replacement or use of a different cold box binder. The processed molding materials from test series A and C fall into landfill class I. Table 49 (The abbreviation NG indicates that the measured values ​​are below the detection limit) Determination from the original substance Parameter Unit Starting sand A-30 B-30 C-30 Dry mass. (1) Wt.% 100 100 100 99.5 Loss on ignition (550 °C) (2) Wt.% TS 3.1 2.1 2.1 1.5 TOC (3) Wt.% TS 2.6 0.4 0.8 0.3 Extractable lipophilic substances (4)Wt.% TS 0.05 < 0.02 < 0.02 < 0.02 Determination from the 10:1 shaking eluate according to DIN EN 12457-4: 2003-01 Parameter Unit Starting sand A-30 B-30 C-30 pH value at 23.3°C + / - 0.2°C (5) 9.8 9.9 9.7 10.1 Water-soluble fraction (6) Wt.% 0.43 1.20 0.95 0.25 Total dissolved solids (6) mg / l 430 1200 950 250 Fluoride (F) (7) mg / l < NG 2.1 < NG < NG Chloride (Cl) (7) mg / l 3.4 7.4 5.9 5.8 Sulfate (SO4) (7) mg / l 23 12 5.2 8.5 Cyanide easily released / Cyanide free (8) mg / l < NG < NG < NG < NG Antimony (Sb) (9) mg / l 0.012 < NG 0.001 < NG Arsenic (As) (9) mg / l 0.134 0.005 0.003 0.006 Barium (Ba) (9) mg / l 0.015 0.087 0.049 0.020 Lead (Pb) (9) mg / l 0.002 0.003 0.003 < NG cadmium (Cd) (9) mg / l < NG < NG < NG < NG Chromium (Cr) (9) mg / l < NG < NG < NG < NG Copper (Cu) (9) mg / l < NG < NG < NG < NG Molybdenum (Mo) (9) mg / l 0.002 < NG 0.001 0.001 Nickel (Ni) (9)mg / l < NG 0,001 < NG < NG Mercury (Hg) (10) mg / l < NG < NG < NG < NG Selenium (Se) (9) mg / l 0.002 < NG 0.001 0.001 Zinc (Zn) (9) mg / l < NG 0.02 < NG < NG Dissolved organic carbon (DOC) (11) mg / l 11 10 2,6 7,0 Phenolindex, wasserdampf-flüchtig (12)mg / l 0.28 0.01 1.2 < NG 1. Determined according to DIN EN 14346: 2007-03 2. Determined according to DIN EN 15169: 2007-05 3. Determined according to DIN EN 15936: 2012-11 (AN,L8: Ver.A; FG,F5:Ver.B) 4. Determined according to the communication of the German Working Group on Waste, Communication 35 short: KW / 04: 2019-09 5. Determined according to DIN EN ISO 10523 (C5): 2012-04 6. Determined according to DIN EN 15216: 2008-01 7. Determined according to DIN EN ISO 10304-1 (D20): 2009-07 8. Determined according to DIN EN ISO 14403-2: 2012-10 9. Determined according to DIN EN ISO 17294-2 (E29): 2017-01 10. Determined according to DIN EN ISO 12846 (E12): 2012-08 11. Determined according to DIN EN 1484: 2019-04 12. Determined according to DIN EN ISO 14402 (H37): 1999-12 3.5 BTX emission potential of the conditioned molding material The starting molding material from the conditioned molding material cycle of the brake disc foundry and the molding materials from cycles A-30, B-30 and C-30 were investigated with regard to their BTX emission potential.For this purpose, the samples are dried at 105°C and ground in a planetary ball mill (Retsch Planetary Ball Mill PM100CM) for 2 minutes at 300 rpm under cold conditions (vessel: 150 ml stainless steel beaker with stainless steel balls). The sample is cooled to -20°C for at least 12 hours, i.e., the grinding bowl of the planetary ball mill was stored at -20°C for at least 12 hours before use to prevent excessive heating of the sample during the grinding process. Subsequently, 10 mg of sample is weighed into a pyrolysis tube. A duplicate determination is performed for each sample. The measurements are carried out with the following equipment: ^ GERSTEL MPS ^ GERSTEL TDU 2 with pyrolysis module ^ Agilent 8890B gas chromatograph with Agilent 5977 mass spectrometer ^ RESTEK 13868 RXI-624Sil MS capillary column, -60 °C-300 °C (320 °C): 30 mx 250 µm x 1.40.25 mm ^ 150 mL stainless steel grinding bowl and stainless steel grinding balls ^ Hamilton electronic holder (VWR Art. No.HAMIDS86200) ^ Hamilton 1 µL syringe (VWR Art. No. 549-1224) ^ Carbotrap B packaged glass inlet liners (450 °C upper temperature limit) (Gerstel Art. No. 013248-005-00) ^ Quartz pyrolysis tubes (Gerstel Art. No. 018437-020-00) ^ Adsorbent matrix Carbopack™ B, 60-80 mesh (VWR Art. No. SUPL20273) ^ Glass wool, silanized (VWR Art. No. SERA22367.01) The following conditions are maintained: Gas chromatography (GC) parameters ^ Temperature program 40 °C start temperature, hold time 4 min 20 °C / min to 60 °C, hold time 35 min 25 °C / min to 300 °C, hold time 10 min ^ Carrier gas Helium 4.6 ^ Inlets Mode Solvent vent ^ Purge flow on split outlet 100 mL / min at 0.02 min ^ Flow rate 50 mL / min at 7.5 psi up to 0.01 min CIS parameters (CIS = cold inlet system - ie the sample is pyrolyzed, the pyrolysis gases are condensed and then evaporated for the GC measurement) ^ Start temperature -4 °C ^ Equilibration time 0.05 min ^ Use of Cryo Cooling yes: ^ Temperature ramp 1 16 °C / s, final temperature 150 °C, hold time 0.1 min ^ Temperature ramp 2 12 °C / s, final temperature 320 °C, hold time 10 min Calibration method: MSD parameters (MSD = mass spectrometric detector) ^ Tune file etune ^ Transfer line temperature 300 °C ^ Ion source temperature 230 °C ^ Quad temperature 150 °C ^ Gain factor 1.000 ^ Ionization mode Electron impact ionization (EI), 70 eV ^ Solvent exposure time 5.5 min ^. ModeScan mode, mass range 35-400 amu, threshold 40, scan speed 1562 u / s TDU parameters (TDU = Thermal Desorption Unit) ^ Start temperature 25 °C ^ Delay time 0.60 min. ^ Temperature ramp 1 Rate: 600 °C / min End temperature: 350 °C Hold time: 5.10 min Pyrolysis parameters ^ Lead time 0.10 min ^ Start temperature 350°C ^ Start time 4 min ^ Heater off yes Calibration was carried out with standards based on benzene, toluene; m- and p-xylene; styrene; o-xylene, ethylbenzene, cumene. Sample method: MSD Parameters ^ Tune File etune ^ Transferline Temperature 300 °C ^ Ion Source Temperature 230 °C ^ Quad Temperature 150 °C ^ Gain Factor 1.000 ^ Ionization Mode Electron Impact Ionization (EI), 70 eV ^ Solvent Exposure Time 0 min ^ ModeScan Mode, mass range 35-400 amu, threshold 40, scan speed 1562 u / s TDU Parameters ^ Start temperature 25 °C ^ Delay time 0.60 min. ^ Temperature ramp 1 rate: 100 °C / min End temperature: 35 °C Hold time: 11.10 min ^ Temperature ramp 2 rate: 600 °C / min End temperature: 50 °C Pyrolysis Parameters ^ Lead time 0.10 min ^ Start temperature 900 °C ^ Start time 10 min ^ Heater off yes Method key figures Linearity Benzene: R 2 = 0.989122 toluene: R 2 = 0.993010 Ethylbenzene: R 2 = 0.992232 m-,p-xylene: R 2 = 0.996029 o-xylene: R 2 = 0.998304 Styrene: R 2 = 0.997786 Cumene: R 2= 0.997454 Working range Benzene: 500-10000 ng (absolute), 50-1000 mg / kg Toluene: 500-10000 ng (absolute), 50-1000 mg / kg Ethylbenzene: 15-300 ng (absolute), 2-30 mg / kg m-,p-Xylene: 45-900 ng (absolute), 5-90 mg / kg o-Xylene: 20-250 ng (absolute), 2-25 mg / kg Styrene: 45-900 ng (absolute), 5-90 mg / kg Cumene: 81-500 ng (absolute), 8-50 mg / kg Detection limit Benzene: LOD = 1.30 ng (absolute) Toluene: LOD = 1.82 ng (absolute) Ethylbenzene: LOD = 0.05 ng (absolute) m-, p-xylene: LOD = 0.29 ng (absolute) o-xylene: LOD = 0.04 ng (absolute) Styrene: LOD = 0.14 ng (absolute) Cumene: LOD = 26.68 ng (absolute) Limit of quantification Benzene: BG = 3.94 ng (absolute), 0.39 mg / kg Toluene: BG = 4.97 ng (absolute), 0.50 mg / kg Ethylbenzene: BG = 0.09 ng (absolute), 0.01 mg / kg m-,p-xylene: BG = 0.61 ng (absolute), 0.06 mg / kg o-Xylene: BG = 0.07 ng (absolute), 0.01 mg / kg Styrene: BG = 0.20 ng (absolute), 0.02 mg / kg Cumene: BG = 80.84 ng (absolute), 8.08 mg / kg The evaluation was carried out using the MassHunter software.The results presented in Table 50 clearly demonstrate that pollutant emissions can be significantly reduced by using an additive according to the invention. The emission potential is significantly reduced, particularly in conjunction with inorganic cores or when fresh mold base material (new sand) is added to the mold material cycle. A significant effect is also observed when ColdBox core sand is added. The emission potential is reduced by over 45% in the model case. Table 50: Pyrolysis (GC-MS) of the mold materials after 30 cycles compared to the original mold material (all data as mg emissions / kg sample material) P. robe Ausgangs- Test series A Test series B Test series C f ormstoffafter 30 cycles after 30 cycles after 30 cycles Parameter Unit Benzene mg / kg 309 27 188 37 Toluene mg / kg 82 5 25 7 Ethylbenzene mg / kg 9 < 2 < 2 < 2 m-, p-xylene mg / kg 12 < 5 < 5 < 5 o-xylene mg / kg < 2 < 2 < 2 < 2 Styrene mg / kg < 16 < 16 < 16 < 16 Cumene mg / kg < 8 < 8 < 8 < 8 BTEX at 900°C mg / kg 412-414 37-46 213-222 44-53 In Table 50, values ​​“< …” mean that the content of the corresponding BTEX compound is below its detection limit. The following applies to the value ranges in the line “BTEX at 900 °C”: The lower limit corresponds to the sum of the contents of BTEX compounds that are above the respective detection limit, so that a value could be determined (in the case of the starting molding material, these are benzene, toluene, ethylbenzene and m-, p-xylene).The upper limit corresponds to the sum of the lower limit and the detection limits of each BTEX compound whose content is below the respective detection limit (in the case of the starting molding material, these are o-xylene, styrene and cumene).

Claims

1. A method for guiding a molding material in a molding material cycle comprising two or more cycles, comprising the following steps: - in an earlier cycle of said two or more cycles of the molding material cycle, casting in a mold comprising molding material bound with smectite-containing clay, resulting in a cast molding material, - processing the cast molding material to result in a first processed molding material, - in a later cycle of said two or more cycles of the molding material cycle, producing a molding material comprising (i) a first processed molding material, and (ii) additives comprising - one or more raw materials from the group consisting of - mold base material, - a second processed molding material produced by processing molding material from uncast molds and / or cores and / or parts thereof,which were produced with an inorganic binder - a third processed molding material produced by processing molds and / or cores and / or parts thereof cast outside the molding material cycle, which were produced with an inorganic binder - an additive containing at least one dehydratable inorganic compound which releases water at a temperature of 150 °C or more, - and optionally smectite-containing clay, wherein at least one of the processed molding materials contains inorganic binder and / or reaction products thereof.

2. The method according to claim 1, wherein the casting takes place in a mold with at least one inserted core produced with an inorganic binder, resulting in a cast molding material comprising material from the cast mold and material from the cast core.

3. The method according to claim 1 or 2, wherein the smectite-containing clay is bentonite.

4. The method according to any one of the preceding claims, wherein the inorganic binder contains water glass.

5. The method according to any one of the preceding claims, wherein the additive contains one or both compounds from the group consisting of aluminum hydroxide and magnesium hydroxide, wherein the proportion of aluminum hydroxide is preferably at least 80%, preferably at least 90%, and more preferably at least 95%, most preferably 99%, based on the total mass of aluminum hydroxide and magnesium hydroxide in the additive.Method according to one of the preceding claims, wherein the mold is cast with iron.

7. Method according to one of the preceding claims, wherein the molding material discharged during processing meets the requirements for landfill class DK I according to Annex 3 of the Ordinance on Landfills and Long-Term Storage (Deponieverordnung - DepV) of April 27, 2009.

8. The method according to any one of the preceding claims, wherein the molding material produced in the later cycle has one or more of the following parameters - a concentration of less than 1.5%, preferably less than 0.8% carbon, based on the mass of the molding material, determined by elemental analysis - a concentration of less than 0.1%, preferably less than 0.05% nitrogen, based on the mass of the molding material, determined by elemental analysis - a concentration of less than 0.05%, preferably less than 0.03% sulfur, based on the mass of the molding material, determined by elemental analysis. - a loss on ignition of at most 5%, preferably at most 3.5%, determined according to VDG Data Sheet P33 (April 1997).

9. Use of the additive as defined in claim 1 in a process according to any one of claims 1 to 8.

Images