Process for wet-chemical modification of a silicate structure, reaction product thereof and use, and corresponding reactor system

Abstract

A process for wet-chemical modification of a silicate structure, wherein the fraction, based on the silicon fraction, of a metal contained in the silicate structure is shifted towards lower values by exposure to a flowing treatment liquid within a reaction space bounded by an outer border, within an exposure time, where the silicate structure is also moved and within the exposure time flows through a flow pathway, and where a ratio of the length of the flow pathway or lengthwise extent of the outer border to the cube root of the reaction space volume is greater than 8, preferably greater than 12, more particularly greater than 16, and the reaction product of said process, and a reactor system.

Description

[0001] Process for the wet chemical modification of a silicate structure, its reaction product, application and corresponding reactor system

[0002] The invention relates to the field of hydrometallurgical wet-chemical dissolution processes. In particular, the invention relates to a method for the wet-chemical modification of a silicate structure, in which the proportion of a metal contained in the silicate structure, relative to the silicon content, is shifted to lower values ​​by exposure to a flowing treatment liquid within a reaction space defined by an external boundary. The silicate structure is also set in motion and flows through a flow path during the exposure time. Such methods are well known, for example, through the large-scale extraction of pure aluminum from natural raw materials such as kaolin, as described, for example, in US Pat. No. 4,239,735.This document proposes a 36% hydrochloric acid (acid lye) as the treatment liquid to ultimately obtain essentially pure AlCl3 ■ 6 H2O crystals from the aluminum dissolved from the silicate structure with the treatment liquid, with further treatment steps. For this purpose, a batch reactor is used in the form of a stirred tank or stirred tank cascade, in which the material is exposed to the acid treatment for a predetermined period of time, approximately two hours or four hours. Such stirred tank reactors are well known to those skilled in the art for such processes, are readily available commercially, and therefore will not be described in detail here.Acid leaching in a stirred tank for 2 hours is also used to convert aluminosilicates fired in an unusual way, namely flash-calcined, into a microporous inorganic particulate material, since a network of channels and pores is formed at bubbles resulting from flash calcination, as described in DE 698 17 732 T3.

[0003] The invention is based on the object of further improving a process of the type mentioned at the outset, in particular with a view to obtaining the desired end product in the most satisfactory quality possible in the simplest possible process design.

[0004] This object is achieved from a process engineering point of view by a further development of the method of the type mentioned at the outset, which is essentially characterized in that the exposure time depends on the speed of movement of the silicate structure and a ratio of the length of the flow path and the cubic root of the reaction space volume is greater than 8, preferably greater than 12, in particular greater than 16.

[0005] The invention is based on the realization that a simpler process design with less operational effort is possible if, unlike the prior art, the goal is not to obtain the metal obtained through treatment in as pure a form as possible as the final product, but rather to obtain the silicate structure that still contains metal after treatment, albeit in a lower ratio to silicon. In the process according to the invention, the exposure time thus depends on the movement speed of the silicate structure (flow reactor or flow reactor), unlike in stirred tanks or their cascades.In this respect, the invention, when expressed in this regard via features of the limitation, provides a further development of the method of the type mentioned at the outset, which is essentially characterized in that the reaction chamber (100) is an elongated reaction chamber of a flow reactor (throughflow reactor) with a length of the outer boundary extending from the reaction chamber inlet located at the start (a) of the flow path to the reaction chamber outlet located at the end (b) of the flow path and a flow cross-section delimited at a respective length position by the outer boundary and a ratio of the length of the outer boundary to the cubic root of the reaction chamber volume is greater than 8, preferably greater than 12, in particular greater than 16.

[0006] Preferably, a method is provided in which the spatial distance between the beginning and end of the flow path is smaller than the length of the flow path, preferably by at least a factor of 2, in particular by at least a factor of 4. This allows a more favorable implementation for applying an energy input into the system.

[0007] Preferably, a process is provided in which the shortest fluid-communicating (allowing fluid communication) connection in the reaction chamber between the beginning and end of the flow path or between the reaction chamber inlet and outlet is not less than 60%, in particular not less than 80%, of the length of the flow path. This reduces deviations from the preferably laminar flow behavior. In this context, it is preferred that the Reynolds number when flowing along the flow path does not exceed 4000, preferably does not exceed 3000, more preferably does not exceed 2500, in particular does not exceed 2000.

[0008] Preferably, a method is provided in which a 3 / s measured volume flow of the treatment liquid together with entrained silicate structure particles is not greater than 8%, preferably not greater than 2%, in particular not greater than 0.8% of the movement speed of the silicate structure measured in m / s. This allows a favorable configuration for efficient energy input. Preferably, a method is provided in which a cross-section through which the treatment liquid and the entrained silicate structure particles flow (the flow cross-section) averaged over the flow path is not greater than 4 dm 2 , preferably not larger than 1 dm 2 , further preferably not larger than 40 cm 2 , again preferably not larger than 20 cm 2 , preferably not larger than 6 cm 2 , especially not larger than 4 cm 2 or even as 2 cm 2This cross-section could be that of a tubular, in particular hose-shaped boundary. In this context, a hose is provided as the boundary, in particular made of a plastic material, such as a PFA hose. The hose could be inserted into a groove of a wall heating system and / or wound up in a coil. Preferably, the quotient of the area of ​​the outer boundary and the volume of the reaction space in cm' 1 measured larger than TT 1 / 2 / 10, preferably larger than TT 1 / 2 / 5, more preferred than (n75) 1 / 2 , even as (4n76) 1 / 2 .

[0009] Preferably, a method is provided in which the reaction chamber is subjected to an energy input provided by an energy source, in particular a heating device.

[0010] Preferably, a process is provided in which the silicate structure particles are added in a comminuted state, wherein a maximum transverse dimension of at least 95% of the silicate structure particles is less than 12%, preferably less than 10%, in particular less than 8% of the flow cross-sectional dimension (diameter or effective diameter) of the reaction chamber, and / or a transverse dimension of at least 50% of the silicate structure particles is greater than 0.04%, preferably greater than 0.1%, in particular greater than 0.3% of the flow cross-sectional dimension. Furthermore, the maximum size of the particles in their largest spatial extent is preferably no more than 40%, in particular less than 30% of the (in particular smallest) flow cross-sectional dimension of the reaction chamber.

[0011] A method is preferably provided in which the movement speed is controlled to an exposure time of less than or equal to 30 minutes, preferably less than or equal to 20 minutes, more preferably less than or equal to 15 minutes, in particular less than or equal to 10 minutes and / or to an exposure time of at least 20 seconds, preferably at least 2 minutes. This promotes the shift towards the desired metal contents which are significantly lower but still present. The length of the flow path is preferably at least 1 m, in particular at least 5 m and / or not more than 500 m, in particular not more than 300 m. The term “metal” on its own or in terms such as “metal content” does not restrict itself to the exclusively metallic form with an oxidation state of 0, but generally also includes mixed forms in the form of mixed oxides, carbonates or sulfates, as typically occur, for example, in phyllosilicates.

[0012] Preferably, a process is provided in which the weight ratio of silicate structure particles to treatment liquid is greater than 5%, preferably greater than 10%, more preferably than 15%, in particular than 20% and / or 60%, preferably 50%, in particular does not exceed 40%.

[0013] Preferably, a method is provided in which the flowing treatment liquid carrying the silicate structure particles is under a pressure of more than 1 bar, preferably more than 2 bar, in particular more than 4 bar, wherein the pressure preferably does not exceed 20 bar, more preferably does not exceed 18 bar, in particular does not exceed 15 bar.

[0014] Preferably, a process is provided which is below a temperature of at least 70°C, preferably at least 100°C, more preferably at least 120°C, in particular at least 140°C, and / or does not exceed 220°C, more preferably does not exceed 210°C, in particular does not exceed 200°C.

[0015] Preferably, a method is provided in which the treatment liquid contains an acid in a concentration of at least 5%, preferably at least 12%, more preferably at least 18%, in particular at least 24%, wherein the concentration is preferably less than 50%, more preferably not exceeding 40%, in particular not exceeding 30%.

[0016] In one proposed process design, the composition of the reactants is changed by adding a reactant, in particular acid, downstream of the reaction chamber inlet at a distance therefrom, with the reaction chamber preferably being continuous between the inlet and the addition point. Such an addition could also occur more than once, for example at additional addition points located even further downstream. For example, the acid or acid mixture used as the reactant, in particular hydrochloric acid, could be added multiple times in this way. Such an addition is not restricted to addition in liquid form; it could also occur by introducing, for example, gaseous HCl.

[0017] By adding the reactants in stages at different reaction points, the reaction kinetics can be influenced as desired by increasing the reactant concentration. Furthermore, the energy efficiency of the process can be influenced. A high dissolution rate of aluminum can be achieved even at Al:Cl ratios of less than 1:3. An AlCl solution, for example, could also be considered as an alternative to HCl.

[0018] For example, a main reaction occurring during acidolysis with hydrochloric acid (= reactant 2) can be briefly described as follows:

[0019] AI2O3 * 2SiO2* 2H2O + 6HCI -> 2AICL + 2SiO2+ 5H2O

[0020] Side effects that may occur include:

[0021] Me x O y + 2 y * HCl -> x * MeCl(2y (X )) + y * H2O

[0022] Where Me stands for Fe, Ca, K, Na, Sr, Mg, etc. As already mentioned, meta-kaolin (calcined kaolin) of varying quality depending on the original deposit can be used as the raw material (= reactant 1), or other comparable materials (e.g., enriched kaolin, not calcined). Of the calcined clays (metakaolin), non-flash calcined clays are preferred, in which the layer structure is not subjected to the effects of flash calcination.

[0023] A reaction mixture fed to the flow reactor (referred to as the first suspension) can initially be placed in a mixing vessel containing water, e.g., hydrochloric acid, and raw material. The acid supply source can preferably be located spatially separate from a protective vessel containing the reactor.

[0024] This first suspension can, for example, be continuously stirred at room temperature and pumped into the flow reactor by means of a pumping device (it is understood that the pump and flow settings depend on the overall setting and can be adjusted in particular within the limits of the values ​​given above, the same applies to the temperature and pressure settings).

[0025] After the reaction has taken place, the reaction mixture (hereinafter referred to as the second suspension) can be collected in a slurry container. With regard to the proportion of the metal contained, based on the silicon content, which is shifted to lower values ​​by the treatment in the reaction chamber, it is preferred that this shift occurs by dissolving the metal from the silicate structure, with preferably more than 60%, more preferably more than 70%, in particular more than 75%, even more than 77% of the metal, preferably aluminum in numerous examples, being dissolved out. However, it is also preferred that more than 3%, preferably more than 5%, more preferably more than 7%, even more than 9% of the originally contained metal, in particular aluminum, remain in the silicate structure.

[0026] In terms of control technology, it is particularly envisaged to meter the reactant, such as HCl, in the form of a closed-loop control, in particular via inline pH measurements and / or viscosity measurements of the reaction solution. In connection with the comparatively small reactor volume, precise metering can thus reduce or avoid the risk of overdosing, which otherwise potentially arise depending on the fluctuating starting material. The temperature of the process is also preferably monitored. In particular, the temperature is recorded at one or more of the following positions in the process, particularly by externally mounted temperature sensors: in the mixing tank, near the pump for pumping into the reaction chamber, the slurry tank for collecting the reaction mixture. Further temperature recordings can be provided between heating reactors, which generate the heat which provides the energy for the reaction, if necessary.also between a heating reactor outlet and a cooling water bath inlet, as well as in the cooling water bath or at the cooling water bath outlet. The room temperature can also be measured and fed into the control system.

[0027] A preferred method is one in which the media-contacting inner surfaces of the outer boundary are corrosion-resistant, and in particular comprise one or more materials selected from the group consisting of SiC, glass, ceramic, or a plastic such as PTFE or PFA. A preferred method is one in which the silicate structure, which still contains metal after this displacement / action, is separated from the treatment liquid after it has flowed through the flow path. The separation could be achieved by a continuous separation process, but also in a batch process, although the latter is also preferred. For example, a chamber filter press can be used for the separation.

[0028] The liquid phase resulting from the separation, which contains polyaluminum chloride, can be collected in a container of specified dimensions, preferably a multiple of the reactor volume. It can be further analyzed and, if necessary, transported to interested parties or further processed.

[0029] Preferably, a process is provided in which the (starting) silicate structure is formed from a natural aluminum silicate, in particular a layered silicate, preferably kaolin or metakaolin produced by its dehydration (but also preferably by conventional calcination, ie not by flash calcination).

[0030] The invention further relates to a reactor system with a reaction chamber delimited by an outer boundary, designed and controlled to carry out a method according to one of the preceding aspects. Thus, the reaction chamber defining the flow path can have one or more addition openings separated from its inlet and from one another to form the addition points explained above. Furthermore, the reactor chamber can be coupled to a heating device to enable energy input. With regard to the heating technology, direct heating is considered, for example in the form of one or more electrical heating devices, for example, via resistance heating, or microwave radiation. However, indirect heating via a heat transfer medium, preferably in the form of thermal oil or superheated steam, is also considered. Combinations of direct and indirect heating can also be provided.One possible design for the flow reactor could, for example, consist of two stacked hollow cylinders, with a tube (also called a reaction tube) surrounding the reaction chamber and wrapped around the outside of the cylinders. The reaction tube is sufficiently resistant to high temperatures and the chemicals used. The reaction tube can, for example, consist of a smooth plastic tube with external reinforcement, such as a braid made of stainless steel. The tube itself can be a smooth tube made of a material such as PTFE as the core.

[0031] In this specific example, the reaction tube can be wound up in such a way that the volume of the reaction space is at least 0.2 l, more preferably at least 0.4 l, in particular at least 0.6 l. Preferably, the volume of the reaction space is not greater than 8 l, more preferably not greater than 6 l, even more preferably not greater than 4 l, in particular not greater than 2 l. In a specific embodiment, the reaction volume could be approximately 0.75 l.

[0032] An external oil bath can be used for the heating system connected to the interior of the hollow cylinders, and a thermal HS oil, e.g. based on silicone, can be used as the tempering fluid.

[0033] In a preferred embodiment, the volume flow through the reaction chamber is controlled to at least one liter per hour, preferably at least two liters per hour, more preferably at least three liters per hour, even higher, such as four liters per hour or more. It is also preferred if this volume flow (flow) is no more than 20 liters per hour, likewise preferably no more than 16 liters per hour, more preferably no more than 12 liters per hour, even no more than 8 liters per hour. It is understood that the invention also contemplates larger systems which overall achieve a significantly higher total flow. For such embodiments, however, it is preferred to feed several reaction chambers in parallel, so that the above-mentioned values ​​are preferably achieved in at least one, preferably several, in particular the majority of the parallel reaction chambers used.

[0034] The flow reactor can be designed as a plug-flow reactor. However, variants with regions of turbulent flow are also conceivable. Even then, it is preferred if the average residence time (volume of the reaction chamber / throughput) deviates by no more than 30%, preferably no more than 20%, in particular no more than 10% from a reference time defined by purely laminar flow under otherwise identical conditions. The invention is not fundamentally restricted with regard to the pump technology used for the flow through the flow reactor. However, peristaltic pumps and / or gear pumps are preferably used. Preferably, at least one pump is arranged upstream in the reaction chamber. However, a further pump can also be provided downstream of the reaction chamber, for example, between a filter device and a tank arranged downstream of the reaction chamber.

[0035] The system's control system can preferably rely on inline measurement values ​​such as pH and / or viscosity. For example, corresponding measuring probes could be installed inline, for example, at or near the exit of the reaction chamber. Separation of the silicate structural particles could be achieved using a membrane filter press, and the separated material could be dried using conventional drying technology. Output tanks can be provided to provide / serve as a source of treatment fluid and (starting) silicate structure. Acidic wash water, which is withdrawn downstream of the separation step, could be recycled to these tanks.

[0036] The silicate structure particles obtained in this way have properties that make them suitable for use as additives for building materials such as concrete.

[0037] The invention thus also relates in general to a material which can be used as an additive for a building material such as concrete which, after the addition of water, is flowable and can set with the formation of strength-forming CSH phases.

[0038] Such additives for cements, mortars, concretes or other hydraulic binders, for example, are widely known in technology and serve to improve one or more of the properties of the building materials in use right up to the parts manufactured from them. Already well known in the historical development of building material systems based on such building materials are the long-standing use of tensile strength-enhancing reinforcing agents, for example in the form of reinforcing steel or in the form of fiber reinforcements made from various materials. Furthermore, there are typical, also commercially available, microsilicas that are widely and commonly used as additives. They have very high SiO2 contents, e.g. 97% (e.g. white microsilica Q1 from BCK Bau-Chemie-Kontor VertriebsGmbH) and other deliberately limited components, such as aluminum with a maximum of 0.3 wt.% (measured in Al2O3).Secondly, EP 0 517 869 B1 describes how a carbonate donor is added to a Portland cement-based system with the aim of quickly achieving higher strengths. Additives such as sodium carbonate, sodium sulfate, and calcium hydroxide are described in DE 4223494 C2, also for achieving high early strengths. Another accelerated system is described in DE 4313148, in which a sulfate carrier and a setting retarder, as well as additives in the form of microsilica or metakaolin as a rebound-reducing additive (for shotcrete), as well as sodium citrate and lignin sulfate, are added to Portland cement, deliberately omitting aluminate-containing setting accelerators. The addition of gluconate is also known, for example from DE 10141864 A1. DE 197 54 826 A1 discloses a separate addition of a reactive CaSO4 compound so that secondary etrengite is not formed after the hardening phase.DE 21 2012 000 163 U1 discloses a concrete additive with a pozzolanic carrier made of spherical fly ash for a photocatalytic material. The addition of halides is initially described in EP 1 719 742 A1 as being particularly effective for accelerating the CSH phase formation. However, this document suggests using ultrafine calcium hydroxide with a very high specific surface area and small grain sizes to achieve high early strengths. Each of the additives listed above has its own specific advantages and disadvantages.

[0039] From a material technology point of view, the invention is generally based on the object of advantageously developing an additive of the type mentioned above, in particular with a view to a suitable combination of properties relating to both technical properties, such as satisfactory compressive strength and in particular satisfactory flexural strength, and the appearance of the final product.

[0040] To this end, the invention provides a further development of a material usable as such an additive of the aforementioned type, which is essentially characterized in that the material comprising silicate-containing particles comprises aluminum, wherein the sum of the aluminum content of the material, calculated as Al2O3, the content of any and preferably provided titanium content of the material, calculated as TiO?, and any and preferably provided zirconium content of the material, calculated as ZrO2, is at least 0.6%, but the Al content is less than 32%, preferably less than 24%, in particular less than 16%, wherein the percentage values ​​(here and below) are each to be understood as weight percent (wt%). In a preferred embodiment, the Al content based on Al2O3 is at least 0.36%, preferably at least 0.42%, in particular at least 0.48%, but contents of at least 0.6%, even at least 0.75% are also contemplated.For further preferred embodiments, Al weight percentages (based on Al2O3) of more than 3%, preferably more than 3.6%, in particular more than 4.2% are also considered in this context. While the main material content is silicon (based on SiC>2), in particular with contents calculated as SiC>2 of more than 64%, preferably more than 80%, more preferably more than 84%, in particular more than 88%, Si contents of less than 94.5%, even less than 94%, or even 93.5% are also considered, particularly with higher Al contents. In variants with somewhat lower aluminum contents or other proportions of the members of the group for the above-mentioned total, higher Si contents are also considered, for example 95% or more, 96% or more, or even 97% or more. The silicate matrix of the particles is preferably layered. The material has reactive SiC>2 and has a pozzolanic effect.

[0041] In a particularly preferred variant, the titanium content, calculated as TiO2, is at least 0.2%, preferably at least 0.3%, more preferably at least 0.4%, although variants of at least 0.5% are also conceivable. In a further preferred embodiment, Zr, calculated as ZrO2, is present in at least 0.02%, preferably at least 0.03%, more preferably at least 0.04%. With regard to TiO2, however, values ​​of less than 0.96%, preferably less than 0.88%, more preferably less than 0.8%, even less than 0.75% are also conceivable. The ZrO2 content is preferably less than 1.0%, preferably less than 0.8%, even less than 0.5%, even less than 0.3%.

[0042] It is particularly preferred that the above-mentioned proportions of Al, Ti, and Zr, in their previously quantified proportions, be part of the silicate matrix of the particles, i.e., are incorporated into the silicate matrix or silicate structure of the particles, and not merely added in the form of additional particles or only adhering to the particles with the silicate matrix. Due to their incorporation into the silicate matrix, these proportions are also found inside the particles, which themselves are preferably mesoporous—in contrast to microporosity, such as would arise during flash calcination due to the blistering effect of flash calcination. However, the invention does not preclude the inclusion of further of these components or additional material portions in the material in a manner not incorporated into the silicate matrix.The invention therefore does not exclude materials which comprise a composite material made of the silicate-containing particles explained above with the portions incorporated in their silicate matrix as a first component and a second component (or further components), wherein the values ​​given so far and below, including the upper limit for the Al content given above, would then refer to this first component.

[0043] In a further variant, it is provided that iron, calculated as Fe2O3, of 0.01%, even 0.02%, but preferably not more than 1.5%, more preferably not more than 0.5%, in particular not more than 0.3% is incorporated into the silicate matrix of the particles.

[0044] Likewise, small amounts of calcium, calculated as CaO, of preferably not more than 0.2%, and / or magnesium, calculated as MgO, of preferably not more than 0.3%, and possibly also potassium, calculated as K2O, of preferably not more than 2%, in particular 1%, may be incorporated.

[0045] In a further preferred embodiment, the particles deviate significantly from a spherical shape in that they have a small dimension in one spatial direction compared to the dimension of the particles in the plane orthogonal thereto. In this sense, the particles are preferably platelet-shaped. d denotes the effective diameter of the expansion surface of a platelet-shaped particle (ie, d=2 (A / u)). 1 / 2, where A is the areal extent of the platelet-shaped particle), the ratio of platelet thickness to d is preferably less than 0.4, more preferably than 0.24, even more preferably than 0.16, in particular less than 0.13. However, this ratio is preferably greater than 0.03, more preferably than 0.04, in particular than 0.05, the values ​​for this ratio relating to the value averaged over the particles of the material (arithmetic mean). In addition, at least 60%, more preferably at least 70%, in particular at least 80% of the individual particles preferably have ratios in these ranges. The areal extent is preferably along the layers in the case of a preferably layered silicate matrix.

[0046] This asymmetrical particle design, compared to a spherical shape, also allows for an anisotropic growth direction of the CSH phases, namely with a predominantly directional component orthogonal to the small expansion direction (platelet thickness) of the respective particles. In this respect, it is also intended that the structure of the particles forms a support for the CSH phases, directing them toward an anisotropic growth direction.

[0047] This aspect of the present invention is also disclosed as independently worthy of protection. Thus, the invention discloses, as independently protectable, a material comprising silicate-containing particles that can be used as an additive for a building material that solidifies upon addition of water, forming strength-building CSH phases. The material has an aluminum content of the particles, based on Al2O3, of preferably less than 32%, more preferably less than 24%, and in particular less than 16%, in which the structure of the particles forms a carrier for CSH phases that directs the growth of the CSH phases toward an anisotropic CSH phase. This promotes the compressive strength and flexural strength of a building material for which the additive is used.

[0048] In this context, it is preferably provided that the material has an activity index of greater than 104%, preferably greater than 106%, in particular greater than 108% according to EN 196-1:2016, and / or a flexural strength-related activity index of greater than 105%, preferably greater than 107%, in particular greater than 109%, wherein a flexural strength test according to EN 196-1:2016 is used instead of the compressive strength test of the said standard for determining the activity index.

[0049] In a further preferred embodiment, the BET surface area of ​​the material is at least 70 m 2 / g, preferably at least 100 m 2 / g, in particular at least 130 m 2 / g, and / or less than 400 m 2 / g, preferably less than 370 m 2 / g, especially as 340 m 2 / g, and / or the oil number of the material is greater than 30, preferably than 35, in particular than 40, and / or less than 110, preferably less than 100, in particular less than 90. In a further embodiment considered (for example based on non-calcined clays), the BET surface area is less than 180 m 2 / g, more preferably less than 165 m 2 / g, especially less than 150 m 2 / g. In a further envisaged embodiment, the BET surface area of ​​the material is within these parameters before any (possible) thermal post-treatment affecting the BET surface area.

[0050] In a further preferred embodiment, the material has a whiteness L* (in the LAB color space) of greater than 92, preferably greater than 95, even more preferably greater than 96, in particular greater than 97. Such values ​​have not been achievable in the prior art, particularly with layered silicate structures. In this respect, the invention also provides a Puzzoian white pigment for building materials.

[0051] Accordingly, the invention also discloses, as independently protectable, a pozzoian white pigment containing silicate particles, which can be used in particular as an additive for a building material which, upon addition of water, flows and solidifies to form strength-building CSH phases, and has a whiteness L* of greater than 92, preferably greater than 95, even more preferably greater than 96, in particular greater than 97. This independent aspect of the invention can be readily combined with the further aspects of the invention explained above and below. Thus, an aluminum content (calculated as Al2O3) is preferably not greater than 32%, more preferably less than 24%, in particular less than 16%. In this context, a Zr content of less than 0.6 wt.%, in particular less than 0.5 wt.%, more preferably than 0.35 wt.%, in particular than 0.2 wt.% is also preferred, again calculated as ZrO2.

[0052] It is also preferred that the dgs of the particles be less than 70 pm, preferably less than 60 pm, more preferably less than 50 pm. It is also preferred that, in wet sieving with a mesh size of 125 pm, the residue is less than 2%, and / or in wet sieving with a mesh size of 63 pm, the residue is less than 3%.

[0053] In a further preferred embodiment, with regard to the size distribution, it is additionally provided that the passage during wet screening with a mesh size of 25 pm is less than 40%, preferably than 30%, in particular than 20%. In a further preferred embodiment, it is provided that the passage during wet screening with a mesh size of 20 pm is less than 40%, preferably than 30%, in particular than 20%. In a still more preferred embodiment, it is provided that the passage during wet screening with a mesh size of 15 pm is less than 40%, preferably than 30%, in particular than 20%. This provides a good combination of satisfactory activity and not too high a water requirement when the material is used in a building material mixture. This can be achieved, for example, by separating a material that previously had a different size distribution, in particular in the form of targeted remixing of its partial quantities sorted by size.In a preferred embodiment, the particles originate from a particularly natural starting material that also has a platelet-like shape, with the values ​​specified above also being preferred with regard to dimensions. Furthermore, a shape factor of the starting material of greater than 24, preferably greater than 27, in particular greater than 30 and / or less than 56, preferably less than 53, in particular less than 50 is preferred.

[0054] Furthermore, from a manufacturing perspective, it is preferred that the particles originate from a process in which an aluminum-containing layered silicate, in particular kaolin, optionally converted into metakaolin after dehydration, has undergone a shift in its Al content relative to the Si content to lower values ​​due to the action of an acid. In this context, it is preferred that the exposure time to the acid, for example HCl, is less than 30 minutes, preferably less than 20 minutes, more preferably less than 12 minutes, more preferably less than 15 minutes, in particular less than or equal to 10 minutes, with exposure times of at least 2 minutes being preferred, preferably in a flow reactor, in particular a plug-flow reactor. For variants with an even greater shift of the Si content to the Al content in favor of the Si content, the exposure times could, however, also be chosen to be longer, for example using a multi-stage process.

[0055] The aluminum-containing phyllosilicate is particularly preferably selected from the group of non-calcined phyllosilicates and calcined, but not flash-calcined phyllosilicates. Of the latter, phyllosilicates calcined for a period of at least 2 minutes are preferred, in particular phyllosilicates calcined in a rotary kiln. This avoids microporosity of the layered structure (due to the blistering effect).

[0056] Furthermore, the invention relates to a mixture of materials comprising the material according to the invention as a component, as well as to an assortment comprising at least two different materials or such mixtures of materials according to one of the preceding aspects, wherein a difference lies in the Al content, Ti content, the BET surface area, grain size and / or the reactivity, individually or in combination.

[0057] Furthermore, the invention relates to the use of a material according to one of the preceding aspects as an additive for a building material that is flowable upon addition of water and solidifies to form strength-forming CSH phases. A silicate structure provided by the invention, which is produced by a process according to one of the preceding aspects and obtained from the silicate structure separated (and dried) after the separation step, represents a preferred embodiment of such a material according to the above material-technical perspective. Before drying, the solid phase obtained after the separation step could also be purified, for example by washing with water, even repeated washing with water, for example until the wash water is pH-neutral.

[0058] The silicate structure particles (hereinafter also: the material) with reduced metal content obtained in this way can preferably be particles that are formed by the process with process parameters such as the exposure time, concentration of the media, pressure and / or temperature, and have one or more of the properties already listed above from a material technology point of view and in particular the following properties:

[0059] The particles may comprise aluminum as metal, wherein the sum of the aluminum content, calculated as Al2O3, the content of any and preferably provided portion of titanium, calculated as TO2, and any and preferably provided portion of zirconium, calculated as ZrO2, is at least 0.6%, but the Al content is less than 32%, preferably less than 24%, in particular less than 16%, wherein the percentage values ​​(here and below) are each to be understood as weight percent (wt%).

[0060] The Al content based on Al2O3 can be at least 0.36%, preferably at least 0.42%, in particular at least 0.48%, but proportions of at least 0.6%, even at least 0.75% are also contemplated. For further preferred embodiments, Al weight percentages (based on Al2O3) of more than 3%, preferably more than 3.6%, in particular more than 4.2% are also contemplated in this context. While the main material content is silicon (based on SiO2), in particular with proportions calculated as SiO2 of more than 64%, preferably more than 80%, more preferably more than 84%, in particular more than 88%, Si contents of less than 94.5%, even less than 94%, even more than 93.5% are also contemplated, especially with higher Al contents. In variants with slightly lower aluminum contents, or other proportions of the members of the group for the above-mentioned total, higher Si contents are also considered, such as 95% or more, 96% or more, or even 97% or more.The silicate matrix of the particles is preferably layered.

[0061] The titanium content, calculated as TiO2, can be at least 0.2%, preferably at least 0.3%, more preferably at least 0.4%, although variants with at least 0.5% are also conceivable. Furthermore, Zr, calculated as ZrO2, can be present in at least 0.02%, preferably at least 0.03%, more preferably at least 0.04%. However, with regard to TiO2, values ​​of less than 0.84%, preferably less than 0.8%, or even less than 0.75% are also conceivable. The ZrO2 content is preferably less than 1.0%, preferably less than 0.8%, even less than 0.5%, or even less than 0.3%.

[0062] It turns out that the above-mentioned proportions of Al, Ti, and Zr, in their previously quantified proportions, are part of the silicate matrix of the particles, i.e., they are incorporated into the silicate matrix or silicate structure of the particles, and are not merely added in the form of additional particles or only adhering to the particles with the silicate matrix. Therefore, due to their incorporation into the silicate matrix, these components are also found inside the particles, which themselves are preferably predominantly mesoporous. A composite material could also be formed from the particles produced in this way, namely from the silicate-containing particles produced in this way with the components incorporated into their silicate matrix as a first component and a second component (or even further components), whereby the values ​​given so far and below, including the upper limit for the Al content given above, would then refer to this first component.

[0063] It can be provided that iron, calculated as Fe2Os, of 0.01%, even 0.02%, but preferably not more than 5%, more preferably not more than 1.5%, in particular not more than 0.5%, is also incorporated into the silicate matrix of the particles, likewise small components of calcium, calculated as CaO, of preferably not more than 0.2%, and / or magnesium, calculated as MgO, of preferably not more than 0.3%, and optionally also potassium, calculated as K2O, of preferably not more than 2%, in particular 1%.

[0064] In one proposed design, the process is controlled by the starting material in such a way that the particles deviate significantly from a spherical shape by exhibiting a small dimension in one spatial direction compared to the dimension of the particles in the orthogonal plane. For example, the particles are then platelet-shaped in this sense. d denotes the effective diameter of the expansion area of ​​a platelet-shaped particle (i.e., d=2 (A / TT)). 1 / 2, where A is the areal extent of the platelet-shaped particle), the ratio of platelet thickness to d is, for example, less than 0.4, also than 0.24, also than 0.16, also than 0.13, even less than 0.1. However, this ratio is preferably greater than 0.03, more preferably than 0.04, in particular than 0.05, whereby the values ​​for this ratio relate to the value averaged over the particles of the material (arithmetic mean). For example, at least 60%, also at least 70%, even at least 60%, more preferably at least 70%, in particular at least 80% of the individual particle ratios have these ranges. The areal extent is preferably along the layers, with a preferably layered silicate matrix.

[0065] The BET surface area of ​​the material after the process and before any thermal post-treatment is then preferably at least 70 m 2 / g, preferably at least 100 m 2 / g, in particular at least 130 m 2 / g, and / or less than 400 m 2 / g, preferably less than 370 m 2 / g, especially as 340 m 2 / g, and / or the oil number of the material is greater than 30, preferably than 35, in particular than 40, and / or less than 110, preferably less than 100, in particular less than 90. In a further embodiment considered (for example based on non-calcined clays), the BET surface area is less than 180 m 2 / g, more preferably less than 165 m 2 / g, especially less than 150 m 2 / G.

[0066] It is also preferred that the dgs of the particles be less than 70 pm, preferably less than 60 pm, more preferably less than 50 pm. It is also preferred that, in wet sieving with a mesh size of 125 pm, the residue is less than 2%, and / or in wet sieving with a mesh size of 63 pm, the residue is less than 3%.

[0067] In a further preferred embodiment, with regard to the size distribution, it is additionally provided that the passage during wet sieving with a mesh size of 25 pm is less than 40%, preferably than 30%, in particular than 20%. In a further preferred embodiment, it is provided that the passage during wet sieving with a mesh size of 20 pm is less than 40%, preferably than 30%, in particular than 20%. In a still further preferred embodiment, it is provided that the passage during wet sieving with a mesh size of 15 pm is less than 40%, preferably than 30%, in particular than 20%. Thus, a predominant to significantly predominant proportion of the material has a corresponding minimum particle size.

[0068] The material can then have a whiteness L* (in the LAB color space) of greater than 86, preferably greater than 92, more preferably greater than 95, even more preferably greater than 96, in particular greater than 97. In this respect, a product of the process according to the invention can also be used as a pozzolanic white pigment for building materials.

[0069] If the particles originate from a natural starting material, its comminuted particles can also have a platelet-like shape, with the values ​​specified above also being preferred with regard to dimensions. Furthermore, a shape factor of the starting material of greater than 24, preferably greater than 27, in particular greater than 30 and / or less than 56, preferably less than 53, in particular less than 50 is preferred.

[0070] As stated above, such a product of the process according to the invention could thus be used as an additive for a building material which, after addition of water, is flowable and can solidify to form strength-forming CSH phases, for example to increase its flexural strength.

[0071] Further features, details and advantages of the invention will become apparent from the following description with reference to the accompanying figures, of which

[0072] Fig. 1 shows a schematic representation of a system for carrying out the method according to the invention.

[0073] The core of the reactor arrangement 1000 shown purely schematically in Fig. 1 is the reaction chamber 100, which is delimited by an outer boundary 110. Within the reaction chamber 100, which in this exemplary embodiment has a volume of approximately 0.5 l, a volume flow of a treatment liquid f with entrained particles p of a silicate structure is generated, in this exemplary embodiment kaolin, along a flow path s from a to b with a length of approximately 25 m in this exemplary embodiment and is subject to an action during this movement that dissolves metal from the silicate structure particles p. In this exemplary embodiment, some of the aluminum contained in the kaolin is dissolved out by the treatment liquid, which is present in the form of an acid, for example hydrochloric acid, here with a concentration of approximately 33%.A source of treatment fluid f is designated 60. Concentrated hydrochloric acid can be selectively added via dosing device 80 to the reaction path or is initially added to maintain the acid concentration at a desired level. Treatment fluid can also be recirculated via recirculation 70, and the supply of concentrated acid can be adjusted accordingly. Reference numeral 90 denotes an energy source that supplies heat to the reactor.

[0074] It is understood, however, that the invention is not limited to the components and dimensions presented in this exemplary embodiment. Variations, particularly in the dimensions, are certainly conceivable. However, for the overall scaling up, not only larger dimensions of the individual components, or in particular the reaction chamber, are considered, but also the multiple parallel use of reaction chambers and, if necessary, other components within an overall system.

[0075] The starting particles p are crushed kaolin fragments, but could also be metakaolin fragments or other crushed ores, preferably aluminum-containing phyllosilicates provided from a source 50 (preferably, the metakaolin fragments or phyllosilicates are not flash-calcined); details of crushing processes to dimensions, preferably in the range 10-500 microns, are known to the person skilled in the art and will not be explained further here.

[0076] In specific embodiments, acidolysis of meta-kaolin (20% slurry) was carried out with HCl in a flow reactor as described above. The acid was added as 22% hydrochloric acid, and the flow rate was varied in several test series around an acid flow of 5.6 liters per hour within a range of + / - 15%, and a target residence time of 8 minutes was also varied within a range of + / - approximately 15%. The temperature between the heating reactor outlet and the cooling water bath inlet was 145°C. The composition of the meta-kaolin used varied slightly within the range of typical composition values; between 80 and 87% of the aluminum was dissolved out. In further specific examples, acidolysis of meta-kaolin (10% slurry) was carried out not with hydrochloric acid, but with AICH as the acid.The flow rate for various test examples was somewhat lower than in the previous examples, ranging between 2.3 and 4.4 liters per hour, and the residence times were correspondingly longer (approximately 10 to 20 minutes). The temperature control was essentially the same as in the previous examples. In this example, the amount of aluminum extracted varied between 78 and 81% of the aluminum originally present in the raw material. The metakaolin can be obtained from calcination in a rotary kiln over several minutes.

[0077] Following the flow path s, the silicate structure particles q with reduced metal content are separated from the treatment liquid fm (now enriched with the dissolved metal) in a separation device 200. The separation device 200 can, with continuous or discontinuous discharge, have one or more separation stages, for example, with the filter technology of a membrane filter press or a filter technology based on a vacuum belt filter, vacuum drum filter, centrifugation, sedimentation, and the like. In addition, the silicate structure particles q with reduced metal content can also be further processed, for example, dried, in a processing stage 300 (drying, chopper). The treatment liquid fm enriched with the dissolved metal can then, if necessary, be fed to further processing steps or applications not explained here.The silicate structure particles can then be processed as a dry substance, such as powder or granules, or as a suspension, for example, as additives for concrete, or even as a pigment. Preferably, the structure or underlying layer structures are still preserved to the extent that they have not been subjected to flash calcination.

[0078] A control system for the process, indicated schematically with the reference number 99, controls the process parameters such as concentration of the media, pressure, temperature, energy input in the reactor chamber, etc. via pump devices or heating devices which are not fully shown in detail.

[0079] In a first embodiment of the present invention, the material is in dry powder form, i.e. in the form of particles, and a composition in weight percent according to chemical analysis (according to EN 196-2:2013) with proportions of

[0080] Other components with even smaller proportions are no longer listed.

[0081] A test for water-soluble substances in the material according to EN ISO 87-3 showed a concentration of 0.29%. The material contains soluble chloride, determined according to EN ISO 87-13, of less than 0.01% and a total chlorine content determined according to ISO 1158 of less than 0.01%.

[0082] The loss on ignition of the material determined according to EN 450-1 is 7.97%.

[0083] This material of the first embodiment shows the following results in the tests described below, in which the addition of the material is based on a cement quantity of a reference cement, namely CEM I 42.5 R 5%: The compressive strength was determined according to EN 196-1:2016; the values ​​given are the mean values ​​of six separately treated samples.

[0084] The onset of setting for the reference cement with the added material from Example 1 was 180 min, only 5 min later than in the reference cement itself. The end of setting was determined to be 240 min (determined according to EN 196-3:2017).

[0085] Further comparative tests with a different reference, namely the same base cement with the same (1.5%) addition of commercially available microsilica, resulted in a slightly lower compressive strength but a 12% higher flexural strength.

[0086] In another example, the main components of the material are (parts with only small traces of content are omitted):

[0087] For this example, a particle size of no larger than 100 pm was determined, with an XD 50 of about 12 pm. At a plane value of about 57,000 cm 2 / g, an activity index of 108% and a whiteness L* of 98.2, it also shows a favorable property as an additive for concrete, for example, due to the relative lightness and the high whiteness.

[0088] In a further embodiment, the material has the following composition: Other elements that are only present in trace amounts are not listed in detail.

[0089] In yet another embodiment, the material has the composition:

[0090] In yet another embodiment, the material has the composition:

[0091] In the production of the particulate material of the above-described embodiments, natural starting materials, namely purified kaolinite in this case, were subjected to a treatment with hydrochloric acid (22 percent) in a reactor under pressure and with the addition of heat. After dissolving some of the aluminum with the hydrochloric acid, the particles of the material were obtained by filtration, with the layered structure of the starting material essentially remaining intact (except for certain delamination effects), thus resulting in essentially platelet-shaped particles. The mesoporous silicate matrix of the particles also contains the aluminum in a desired amount, as well as other components as explained above. Furthermore, by avoiding flash calcination, the blistering effect can be avoided, and a mesoporous structure (rather than a microporous structure) can be obtained.

[0092] In a further embodiment, materials are created as in the preceding examples and separated according to particle size using a sieve (e.g., mesh size 20 μm), and the coarser-grained portion is provided as the material, or mixed with a fraction of the previously filtered portion and provided as the material. Preferably, at least 60 wt.% of the particles from the coarser-grained portion remain.

[0093] It is understood that the explanations in the two preceding paragraphs regarding the manufacturing process, although preferred, are exemplary, and other silicate structures can also be used as starting material, such as other layered silicates, framework silicates, the type of processing of the starting material such as the degree of comminution, etc., or others can be varied. However, as explained several times above, flash calcination is preferably omitted. Likewise, it is understood, although preferred, that the invention is not limited by details of such a manufacturing process, for example with regard to the acid or acid combination used, exposure times, specific reactor types, and the like.

[0094] The invention is not limited to the above embodiments. Rather, the features of the above description and the following claims, individually or in combination, may be essential for the realization of the invention in its various embodiments.

Claims

Claims 1. A method for the wet-chemical modification of a silicate structure (p), in which the proportion of a metal contained in the silicate structure (p), based on the silicon proportion, is shifted towards lower values ​​within an exposure time by the action of a flowing treatment liquid (f) within a reaction space (100) delimited by an outer boundary (110), wherein the silicate structure is also set in motion and flows through a flow path (s) within the exposure time, characterized in that the exposure time depends on the speed of movement of the silicate structure and a ratio of the length of the flow path to the cubic root of the reaction space volume is greater than 8, preferably greater than 12, in particular greater than 16.

2. A method for the wet-chemical modification of a silicate structure (p), in particular according to claim 1, in which the proportion of a metal contained in the silicate structure (p) relative to the silicon content is shifted to lower values ​​within an exposure time by the action of a flowing treatment liquid (f) within a reaction space (100) delimited by an outer boundary (110), wherein the silicate structure is also set in motion and flows through a flow path (s) within the exposure time, characterized in thatthat the reaction chamber (100) is an elongated reaction chamber of a flow reactor with a length of the outer boundary extending from the reaction chamber inlet located at the beginning (a) of the flow path to the reaction chamber outlet located at the end (b) of the flow path and a flow cross-section delimited at a respective length position by the outer boundary and a ratio of the length of the outer boundary and the cubic root of the reaction chamber volume is greater than 8, preferably greater than 12, in particular greater than 16., 3. Method according to claim 1 or 2, wherein the direct spatial distance between the beginning (a) and the end (b) of the flow path is less than the length of the flow path, preferably by at least a factor of 2, in particular by at least a factor of 4.

4. Method according to one of claims 1 to 3, in which the shortest fluid-communicating connection between the beginning and end of the flow path or between the reaction chamber inlet and the reaction chamber outlet is not less than 60%, in particular 80% of the length of the flow path.

5. Method according to one of the preceding claims, in which a 3 / s measured volume flow of the treatment liquid together with entrained silicate structure particles is not greater than 8%, preferably not greater than 2%, in particular not greater than 0.8% of the movement speed of the silicate structure measured in m / s.

6. Method according to one of the preceding claims, in which a cross-section through which the treatment liquid and the flowing silicate structure particles flow is averaged over the flow path not greater than 4 dm 2 , preferably not larger than 1 dm 2 , especially not larger than 6 cm 2 .

7. A method according to any one of the preceding claims, wherein the silicate structure- Particles are added in a comminuted state, wherein a maximum transverse dimension of at least 95% of the silicate structure particles is less than 12%, preferably than 10%, in particular than 8% of the flow cross-section of the reaction space, and / or a transverse dimension of at least 50% of the silicate structure particles is greater than 0.04%, preferably greater than 0.1%, in particular greater than 0.3% of the flow cross-section.

8. Method according to one of the preceding claims, in which the Movement speed is controlled to an exposure time of less than or equal to 30 minutes, preferably less than or equal to 20 minutes, more preferably less than or equal to 15 minutes, in particular less than or equal to 10 minutes.

9. A method according to any one of the preceding claims, wherein the volume ratio of the silicate structure particles to the treatment liquid is greater than 5%, preferably greater than 10%, more preferably than 15%, in particular than 20% and / or 60%, preferably 50%, in particular not exceeding 40%.

10. Method according to one of the preceding claims, in which the flowing treatment liquid carrying the silicate structure particles is under a pressure of more than 1 bar, preferably more than 2 bar, in particular more than 4 bar, wherein the pressure preferably does not exceed 20 bar, more preferably does not exceed 18 bar, in particular does not exceed 15 bar.

11. Process according to one of the preceding claims, which is below a temperature of at least 70 °C, preferably at least 100 °C, more preferably at least 120 °C, in particular at least 140 °C, and / or does not exceed 220 °C, more preferably does not exceed 210 °C, in particular does not exceed 200 °C.

12. Method according to one of the preceding claims, wherein the treatment liquid is an acid in a concentration of at least 5%, preferably at least 12%, more preferably at least 18%, in particular at least 24%, wherein the concentration is preferably less than 50%, more preferably not exceeding 40%, in particular not exceeding 30%.

13. Process according to one of the preceding claims, in which the composition of the reaction mixture is changed by adding a reactant, in particular acid, downstream of the reaction chamber inlet and at a distance therefrom, the reaction chamber preferably being formed as a continuous structure between the inlet and the point of addition.

14. Method according to one of the preceding claims, in which the media-contacting inner surfaces of the outer boundary are designed to be corrosion-resistant, and in particular comprises one or more materials from the group consisting of SiC, glass, ceramic or a plastic such as PTFE or PFA.

15. Method according to one of the preceding claims, in which the silicate structure (q) still containing metal after this displacement is separated from the treatment liquid after flowing through the flow path.

16. Process according to one of the preceding claims, in which the silicate structure is formed from a natural aluminum silicate, in particular a layered silicate, preferably kaolin or metakaolin formed by its dehydration, wherein preferably non-flash calcined aluminum silicates / layered silicates / metakaolin and / or non-calcined aluminum silicates / layered silicates / kaolin are used, the latter preferably being fired in a kiln, in particular a rotary kiln, for at least 2, in particular at least 4, preferably at least 6 minutes.

17. Reactor system with a reaction chamber delimited by an outer boundary, designed and controlled to carry out a process according to one of the preceding claims.

18. A material containing silicate particles which can be used as an additive for a building material which is flowable after the addition of water and which can solidify with the formation of strength-forming CSH phases, characterized in that the material contains aluminum, wherein the sum of the aluminum content, calculated as Al2O3, a content of any preferably provided content of titanium, calculated as TiO2, and any preferably provided content of zirconium, calculated as ZrO2, is at least 0.56 wt.%, preferably at least 0.64 wt.%, in particular at least 0.72 wt.%, but this Al content based on Al2O3 is less than 32 wt.%, preferably less than 24 wt.%, in particular less than 16 wt.%.

19. Material according to claim 18, having an Al content based on Al2O3 of at least 0.36 wt.%, preferably at least 0.42 wt.%, more preferably at least 0.48 wt.%, even more preferably at least 0.6 wt.%, in particular at least 0.75 wt.%.

20. Material according to claim 19, with an Al weight percentage of more than 3%, preferably more than 3.6%, in particular more than 4.2%, and / or a Si content of less than 94.5%, even less than 94%, even more than 93.5%.

21. Material according to one of claims 18 to 20, having a titanium content of at least 0.2 wt.%, preferably at least 0.3 wt.%, more preferably at least 0.4 wt.%, in particular at least 0.5 wt.%.

22. Material according to one of claims 18 to 21, with a zirconium content, calculated as ZrO2, of at least 0.02 wt.%, preferably at least 0.03 wt.%, more particularly at least 0.04 wt.%.

23. Material according to one of claims 18 to 22, in which the material components defined in the preceding claims are also part of the silicate matrix of the particles in their quantified proportions.

24. Material according to one of claims 18 to 23, in which at least the predominant number of the particles have a small dimension in one spatial direction compared to the dimension of the particles in the plane orthogonal thereto.

25. Material according to one of claims 18 to 24, in which the silicate matrix of the particles has a layered structure, and in particular the planar extent of the particles runs along the layers of the silicate matrix.

26. Material according to one of claims 18 to 25, wherein the structure of the particles formed by the silicate matrix forms a support for CSH phases directing them towards an anisotropic CSH phase growth direction.

27. Material according to one of claims 18 to 26, wherein the particle size is less than 70 pm, preferably less than 60 pm, more preferably less than 50 pm.

28. Material according to any one of claims 18 to 27, whose BET surface area is at least 70 m 2 / g, preferably at least 100 m 2 / g, in particular at least 130 m 2 / g, and / or less than 400 m 2 / g, preferably as 370 m 2 / g, especially as 340 m 2 / g, and / or whose oil number is greater than 30, preferably than 35, in particular than 40, and / or less than 110, preferably less than 100, in particular less than 90.

29. Material according to one of claims 18 to 28, having an activity index of greater than 104%, preferably greater than 106%, in particular greater than 108%, and / or an activity index related to flexural strength of greater than 105%, preferably greater than 107%, in particular greater than 109%.

30. A white pigment containing silicate particles, particularly according to one of claims 18 to 29, which can be used as an additive for a building material which is flowable after addition of water and solidifies with the formation of strength-forming CSH phases, having a whiteness L* of greater than 92, preferably greater than 95, further preferably greater than 96, in particular greater than 97.

31. Material according to any one of claims 18 to 30 in the form of a silicate structure produced by a process according to any one of claims 1 to 16 and obtained from the silicate structure separated after the separation step according to claim 15.

32. Multi-component mixture of substances with a first component in the form of a material according to one of claims 18 to 30 and a second component, in particular comprising quartz.

33. Assortment comprising at least two different materials provided according to any one of claims 18 to 30 or different material mixtures according to claim 32, wherein there is a difference in the Al content, the average grain size and / or the BET surface area.

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