Method for separating elemental phosphorus from iron oxide-containing and phosphate-containing materials

Abstract

A method for separating elemental phosphorus from an iron oxide-containing and phosphate-containing material, comprising at least the following steps: providing at least one iron oxide-containing and phosphate-containing material; adding at least one aluminum support to the at least one iron oxide-containing and phosphate-containing material, and melting the at least one aluminum support with the at least one iron oxide-containing and phosphate-containing material to form an aluminum-containing, and optionally aluminum oxide-containing, phosphate slag melt; and separating the aluminum-containing, and optionally aluminum oxide-containing, phosphate slag melt from the gaseous elements phosphorus, iron, and Al in a melting vessel (11). 2 O 3 reacting the slag with the gaseous element phosphorus to extract iron and Al 2 O 3 and extracting the contained slag.

Description

[Technical field]

[0001] The present invention relates to a method for separating elemental phosphorus from iron oxide-containing and phosphate-containing materials, in particular from waste materials such as sewage sludge (ash), animal meal, bone meal and / or steel mill slag, preferably together with materials such as apatite, phosphate rock and / or phosphorite, and to an apparatus for carrying out the method according to the invention. [Background technology]

[0002] The price of phosphate rock has been steadily increasing in recent times due to the scarcity of suitable raw material sources. Moreover, utilized phosphate rocks increasingly contain significant levels of uranium, cadmium, selenium and other harmful by-products. Such associated elements can only be removed at great expense, and as a result, the use of phosphates from such contaminated ores is becoming increasingly uneconomical.

[0003] On the other hand, waste materials may contain relatively high levels of phosphorus compounds. This is the case, for example, for sewage sludge, animal meals, bone meal and / or steel mill slag.

[0004] High purity phosphorus starting material, which can be prepared from elemental phosphorus (P4, white phosphorus), is needed in particular for food production and also for the pharmaceutical industry, but production is becoming increasingly difficult and is currently no longer practicable, at least in Europe.

[0005] The main problem in the recovery of elemental phosphorus from starting materials of the type mentioned above, in particular from waste materials, such as sewage sludge, animal meal, bone meal and / or steelworks slag, and / or from materials such as apatite, phosphate rock and / or phosphorite, lies in the formation of phosphorus sludge, which is formed, for example, during the Wöhler process, from silicates and carbon-containing accompanying substances of iron oxide-containing and phosphate-containing materials, which contain various phosphorus species. The phosphorus sludge is highly toxic and its disposal is a major problem, since it makes the extraction of elemental phosphorus using previously known processes more or less unpromising from an economic point of view. Moreover, in conventional processes, the recovery of elemental phosphorus involves the production of phosphine (specifically PH3, and generally PH4 in the context of the present invention) which is a volatile and highly toxic odorless gas. x ) is the main problem. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is therefore based on the task of creating a method and a corresponding device that allows the recovery of elemental phosphorus from the aforementioned starting materials without the formation of phosphorus sludge or phosphine. At the same time, in comparison with the prior art methods, the formation of undesirable iron-phosphorus alloys, such as iron phosphide, ferrophos and Fe2P, as well as CO2 emissions, should be avoided. [Means for solving the problem]

[0007] To solve this task, the method according to the invention comprises at least the following steps: Providing at least one iron oxide and phosphate containing material; adding at least one aluminum support to the at least one iron oxide and phosphate containing material and melting the at least one aluminum support with the at least one iron oxide and phosphate containing material to form an aluminum-containing and optionally aluminum oxide-containing phosphate slag melt; reacting an aluminum-containing and optionally alumina-containing phosphate slag melt with gaseous elemental phosphorus, iron and Al2O3-containing slag in a melting vessel; extracting gaseous elemental phosphorus and extracting iron and Al2O3-containing slag; Includes.

[0008] In the process according to the invention, the starting material is melted together with at least one aluminum support. In the resulting melt, which is an aluminum-containing phosphate slag melt and may possibly already initially contain aluminum oxide, the exothermic reaction of elemental phosphorus (P2, gaseous) and metallic iron then occurs. The process according to the invention thus utilizes an autothermal redox reaction between the redox partners iron oxide, phosphorus oxide (phosphate) and aluminum, which are present in different reduction stages, whereby the redox reaction is strongly exothermic and the reaction is therefore self-sustaining.

[0009] In the molten phase, the phosphate slags form easily mobile conductive cation and anion clusters (ion complexes). For example, the cation clusters are Fe 2+ , Ca 2+ , Mg 2+ , Na + , K + The anion cluster is formed from, for example, PO4 3- , SiO 3- , SiO4 4- , SiO3 2- and AlO3 3- A careful electrothermal (electrolysis of the molten stream) and / or aluthermic partial reduction of the phosphorus oxide of the phosphate slag melt leads to a very rapid reduction of the phosphate to gaseous P2 and of the iron oxide to metallic iron. Due to the exothermic nature of the process according to the invention, a large amount of heat is released, so that the reaction must be maintained and cooled by itself.

[0010] Advantageously, it may be provided that aluminum dross is used as the aluminum carrier. The dross is produced during the electrolysis of alumina to produce metallic aluminum or during the melting of scrap aluminum. The dross consists of metallic aluminum, which is surrounded by an aluminum oxide film. The dross is formed due to the oxidation of aluminum to alumina on the surface of the corresponding electrolytic or melting bath and is difficult to dispose of. Attempts have been made to destroy the oxide film, for example by using fluorides, but this obviously leads to even more serious waste and exhaust problems from such processes. The use of dross in the process according to the invention thus has the advantage that in addition to the aluminum desired for reduction, alumina, i.e. the reaction product of the process according to the invention, is also added, so that the violent exothermic reaction is mitigated and the heat generation is therefore reduced. At the same time, a slag with a particularly high alumina content is obtained, which ensures outstanding early strength values ​​in the cement containing this slag.

[0011] The conversion takes place so rapidly that no intermediates of phosphorus, as well as phosphates and compounds of phosphorus with the starting material, can be formed, and thus the formation of phosphorus sludge and phosphines is prevented and effectively avoided. Aluminates and non-metallic accompanying substances accumulate in the slag, while heavy metals are sometimes contained, for example, in sewage sludge or steel mill slag, or mill scales are alloyed with the formed iron. In this way, pure phosphorus is obtained directly in the gas phase, and the initially formed P2 can be converted into further phosphorus modifications, for example P4, by cooling methods known per se, for example by cooling and quenching with water, or preferably by indirect cooling using a regenerative heat exchanger.

[0012] After shock cooling, the formed slag can be used in the cement industry as a high quality hydraulic binder, whereas, if necessary, additional aggregates can be added to the slag depending on the needs of the target analysis of the slag. For example, by increasing the addition of metallic aluminum, the SiO2 content of the target slag can be reduced while simultaneously increasing the aluminum content. In this case, FeSi-containing molten iron with a slightly increased aluminum content is produced. This iron alloy can be advantageously used as a deox alloy addition in steel metallurgy.

[0013] Regarding the mixing of the starting materials and the aluminum support, according to a preferred embodiment of the present invention, the at least one iron oxide and phosphate-containing material can be provided as a phosphate slag melt in a melting vessel, and the at least one aluminum support is added to the phosphate slag melt. In this case, the phosphate slag melt can be provided from an oxidation process that is already almost free of contaminants, so that the formation of undesirable toxic substances is avoided from the start.

[0014] According to an alternative preferred embodiment of the invention, with regard to the mixing of the starting materials and the aluminum support, it may also be provided that the solid materials are in particular sewage sludge ash with lime support and / or apatite and / or phosphate rock, provided as iron oxide and phosphate-containing materials, and that solid metallic aluminum is added as at least one aluminum support. In this case, the aluminum support is therefore not added to the already present phosphate slag melt, but the starting materials are in solid form and come into contact with the metallic aluminum of the solid aluminum support during the addition. Here, the substances are preferably ground to a fine powder in order to increase the reaction surface. The mixture obtained by the adding step must first be ignited in some way. This can be achieved with a spark plug or a flame, or by melting the phosphate slag already present in the melting vessel. As the reaction proceeds, it is sustained by itself due to the exothermic nature of the redox reaction.

[0015] As already mentioned several times, the redox reaction between iron oxide, phosphorus oxide and aluminum is highly exothermic, and therefore a large amount of heat is generated in the process according to the invention, most of which requires the reaction to be cooled. In addition to the obvious possibility of cooling the melting vessel or the phosphate slag melt by various cooling coils, heat exchangers, etc., according to a preferred embodiment of the invention, it is also possible to proceed in such a way that for this purpose an Al2O3 support is added to the aluminum-containing and optionally alumina-containing phosphate slag melt. Al2O3 (aluminum oxide) is also a product of the redox reaction of the process according to the invention. The addition of the preferably cold alumina support shifts the equilibrium of the redox reaction towards the starting materials, thus inhibiting the reaction rate and therefore also the release of heat. In this way, overheating of the phosphate slag melt or the melting vessel can be effectively avoided at the point of heat release without introducing non-reactive chemical species into the process. In this context, it is particularly advantageous to increase the Al2O3 content of the target slag, since the addition of Al2O3 is favourable for the production of fast-binding cement.

[0016] With optimized process control, it is advantageous, especially with regard to the desired viscosity of the melt, to adjust the basicity (CaO / SiO2) of the aluminum-containing and optionally alumina-containing phosphate slag melt, preferably by adding CaO and / or SiO2 supports, to values ​​of 0.65 to 1.4, preferably 0.85 to 1.2 and particularly preferably 1, which correspond to the preferred embodiments of the present invention. In detail, chemical analysis of the target slag shows the following ratios of main components (in wt%): CaO 22~56 Al2O332~55 SiO21~22 Fe2O30.15~3 MgO 2~15 P 0.05 to 1.2 This corresponds to the directional analysis of high quality alumina fused cement.

[0017] Preferably, the tin bath is provided as a cathode body in the melting vessel below the aluminum-containing and optionally alumina-containing phosphate slag melt, and at least one anode body, preferably made of graphite, platinum or magnetite spinel, is provided to be immersed in the aluminum-containing and optionally alumina-containing phosphate slag melt. This realizes the electrochemical effects of the method according to the invention, which are described below. The choice of material for the anode body can be made according to various aspects. Graphite electrodes are certainly cheap to buy in the method according to the invention, but they are decomposed relatively quickly by nascent oxygen to form carbon dioxide. However, the formation of carbon dioxide should be avoided for reasons of climate protection, and frequent anode replacement is undesirable from an economic point of view. It has been observed that anodes made of platinum or magnetite, especially magnetite spinel, are expensive, especially in the case of platinum, but have a very long service life. Another advantage is that only oxygen and not carbon dioxide is produced in such electrodes.

[0018] In order to minimize the use of metallic aluminum as much as possible, it may be provided that a direct current, preferably 3V to 15V, preferably 6V to 12V, more preferably 8V to 10V, is applied to the cathode and anode bodies corresponding to the preferred embodiment of the present invention. This allows the reaction to be driven beyond the natural chemical equilibrium by electrolysis. The iron formed accumulates in the tin bath and undercoats the tin bath when it reaches saturation.

[0019] Alternatively, however, when the reaction is more or less complete, it is also preferred to withdraw the current from the cathode and anode bodies, as for direct current, for optimal adjustment of the quality of the starting materials as well as the basicity and temperature of the phosphate slag melt. In this case, the method according to the invention provides electrical energy by forming a voltage between the anode and the cathode, which can induce the flow of an external current, which can be used in any conceivable manner. At the same time, this galvanic chain can also be used to measure the progress of the reaction in the phosphate slag melt. If the iron oxide and phosphorus oxide of the phosphate slag melt are completely reduced and are present in elemental form, no current flows. Experiments have therefore shown that the current flow decreases with the progress of the phosphate slag reduction. The further added aluminum (metallic aluminum) no longer reacts with the now reduced phosphate slag melt.

[0020] In order to be able to obtain the products of the cathodic and anodic reactions separately, according to a preferred embodiment of the invention, a cathode body is provided in a first region of the melting vessel in a recess arranged in a partial region of the bottom surface of the melting vessel, and at least one anode body is provided in a second region of the melting vessel different from the first region, with the provision that gaseous phosphorus is withdrawn from the first region and oxygen is withdrawn from the second region. By arranging the cathode body in a region different from the region in which the anode body is arranged, the products of the cathodic and anodic reactions are generated in separate locations in the melting vessel or in the gas space of the melting vessel and can therefore also be withdrawn separately. At the cathode these are iron and gaseous phosphorus, at the anode, in the case of an inert anode, only oxygen in gaseous form is generated. The formed iron accumulates in the tin bath and undercoats it when the tin bath reaches saturation and can be withdrawn from the recess.

[0021] The device according to the invention for carrying out the method according to the invention comprises a melting vessel formed by a refractory-lined housing, a phosphate slag melt containing aluminum and optionally aluminum oxide arranged in the melting vessel, a gas chamber closed by a housing above the phosphate slag melt, as well as a feed device for the substance containing iron oxide and phosphate, and at least one discharge device for gaseous elemental phosphorus.

[0022] In this device according to the invention, the aluminum support can be melted together with the iron oxide-containing and phosphate-containing materials, the starting materials. In the resulting melt, which is a phosphate slag melt containing aluminum and optionally alumina, an exothermic release of elemental phosphorus (P2, gaseous) and metallic iron occurs, which corresponds to the rate of addition of metallic aluminum. After reduction or conversion, the original phosphate slag melt is substantially free of phosphorus and iron.

[0023] As previously described in connection with a preferred embodiment of the method according to the invention, if at least one iron oxide and phosphate-containing material is provided in the melting vessel as a phosphate slag melt and at least one aluminum carrier is added to the phosphate slag melt, the apparatus according to the invention is preferably characterized in that the feed device has a first tube penetrating the housing, in which a conveying device, preferably in the form of a screw conveyor, for the at least one aluminum carrier is arranged. Through this first tube, the aluminum carriers can be introduced into the housing of the device and finally into the phosphate slag melt, where they are melted together with the phosphate slag melt. The reduction process of the phosphate slag melt corresponds to the addition rate of metallic aluminum.

[0024] According to an alternative variant of the invention described previously, it is provided that a solid material, in particular sewage sludge ash with lime support and / or apatite and / or rock phosphate, is provided as the iron oxide and phosphate-containing material, and that solid metallic aluminum is added as the aluminum support. In this case, the addition as solid of aluminum scrap, preferably magnesium alloyed, phosphate-containing steel slag, phosphate-containing mill scale, etc. is also conceivable. In this case, the device according to the invention is preferably characterized in that the feeding device comprises a first tube penetrating the housing, in which a second tube is arranged, preferably forming an annular gap concentric with the first tube, one of the first and second tubes is designed to feed the material containing iron oxide and phosphate, the other of the first and second tubes is designed to feed the aluminum support, the first tube protruding beyond the second tube and penetrating the housing at its end. This feeding device allows two solid components, i.e. iron oxide-containing and phosphate-containing materials or starting materials and aluminum carriers, to be fed together into the device, whereby a first tube protrudes beyond the second tube and penetrates the housing at its end, establishing contact between the two components in the feeding device, which causes the formation of an autothermal reaction front, where the aluminum carrier melts with the iron oxide-containing and phosphate-containing material and where the reaction, which is exothermic, begins. The resulting aluminum-containing and, if necessary, alumina-containing phosphate slag melt then passes into the melting vessel and into the existing phosphate slag melt, where complete conversion to elemental iron and phosphorus takes place. Both the first and second tubes may contain suitable conveying means for conveying the components. In the end region of the second tube, an ignition device is provided for the aluminum carrier and the iron oxide-containing and phosphate-containing materials, although ignition of the mixture of the two aforementioned components may also be brought about by heating the phosphate slag melt.

[0025] To electrochemically influence the method according to the invention, the device according to the invention is preferably further designed in such a way that it has a cathode body arranged under the aluminum-containing and optionally alumina-containing phosphate slag melt and at least one anode body is immersed in the aluminum-containing and optionally alumina-containing phosphate slag melt. The cathode and anode bodies are obtained in a known manner with electrical leads forming a circuit.

[0026] In order to be able to obtain the products of the cathodic and anodic reactions separately, according to a preferred embodiment of the invention, the cathode bodies are arranged in a first region of the melting vessel in a recess arranged in the bottom surface of the melting vessel, and at least one anode body is arranged in a second region of the melting vessel laterally spaced from the first region, with a further extraction device arranged in the second region. By arranging the cathode bodies in a region different from the region in which the anode bodies are arranged, the products of the cathodic and anodic reactions are generated in separate locations in the melting vessel or in the gas space of the melting vessel and can therefore also be extracted separately. At the cathode these are iron and gaseous phosphorus, at the anode, in the case of an inert anode, only oxygen in gaseous form is generated. The iron formed accumulates in the tin bath and, if the tin bath reaches saturation, undercoats it and can be extracted from the recess.

[0027] In order to achieve the most complete separation of the products of the cathodic and anodic reactions in the gas space of the device according to the invention, the invention is preferably further designed such that the dividing wall dividing the gas space into two sections separated from each other is immersed in the aluminum-containing and optionally alumina-containing phosphate slag melt between the first and second sections, so that the products of the cathodic reactions cannot enter the first region with the anode and vice versa and can be withdrawn separately in this way.

[0028] On the other hand, when the gaseous products of the cathodic and anodic reactions are combined in an exothermic reaction, very pure P2O5 is formed. The P2O5 formed in this reaction can be directly converted by hydrolysis to food-grade phosphoric acid, which is therefore pure enough for use.

[0029] According to a preferred embodiment of the invention, the cathode body is formed by a tin bath. A tin bath as a cathode has the advantage that, in addition to the iron formed in the device according to the invention during the method according to the invention, heavy metals which may be contained under certain circumstances, for example in sewage sludge, steel mill slag or mill scale, are alloyed in the formed iron and therefore fixed. As soon as the tin bath is saturated with iron, the iron formed in the method according to the invention undercoats the tin bath and can be extracted.

[0030] To extend the service life of the device according to the invention, the tin bath is contained in a carbon inclusion arranged in a recess corresponding to a preferred embodiment of the invention. The carbon inclusion may preferably be formed as a graphite body or may consist of a carbon-containing mass.

[0031] According to a preferred embodiment of the invention, the anode body may be made of graphite, platinum or magnetite spinel. Graphite electrodes are widely used in the prior art and, when the method according to the invention is carried out with the device according to the invention, cause the formation of CO and possibly CO2 at the anode. The CO (carbon monoxide) can then be thermally recycled. The graphite anode is consumed in this method and must be periodically renewed. The advantages of the other anode materials mentioned have already been explained above in connection with the method according to the invention.

[0032] According to an alternative embodiment, to enable a CO-free process, the invention may be further embodied in that at least one anode body is made of high alloy steel, the steel being preferably coated with platinum, which essentially extends the good service life of the high alloy steel anode and also provides catalytic properties.

[0033] Furthermore, it may also be used as an anode body in a Soderberg electrode.

[0034] As mentioned above, when carrying out the method according to the invention, a large amount of heat is released in the device according to the invention, which can sometimes affect the apparatus. To prevent this, at least one anode body can be designed to be cooled, preferably by channels arranged inside the anode body for a tin melt, a salt melt or a sodium melt, or for gas cooling, preferably with nitrogen or argon, in accordance with a preferred embodiment of the invention.

[0035] As previously mentioned, in order to minimize the use of aluminum as much as possible, it may be provided that a direct current, preferably between 3V and 15V, preferably between 6V and 12V, more preferably between 8V and 10V, is applied to the cathode and anode bodies, so that the reaction can be driven beyond the natural chemical equilibrium by electrolysis. To this end, according to a preferred embodiment of the invention, the device comprises means for applying a direct current to the cathode and anode bodies.

[0036] Alternatively, however, it is also preferred that when the reaction is more or less complete, for optimal adjustment of the quality of the starting materials and the basicity and temperature of the phosphate slag melt, a direct current is withdrawn from the cathode and anode bodies. In this case, the method according to the invention provides electrical energy that can be used in any conceivable way. To this end, the device has, according to a preferred embodiment of the invention, means for obtaining a direct current from the cathode and from the anode bodies. The anodic reaction can be specified as follows: Al → Al 3+ +3e - This represents electron emission and, as a result, oxidation of the metallic aluminum.

[0037] The cathodic reaction may be designated herein as follows: P 3+ +3e -→P Fe 3+ +3e - →Fe This represents the uptake of electrons and hence the reduction of iron and phosphorus oxides.

[0038] The invention is explained in more detail below with reference to example embodiments illustrated in the drawings. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 shows a schematic diagram of a first device according to the invention. [Diagram 2] FIG. 2 shows a representation of a device according to the invention having a cathode body and several anode bodies. [Diagram 3] FIG. 3 shows a supply device according to a first embodiment of the device according to the invention, preferably for the device according to FIG. [Figure 4] FIG. 4 shows an embodiment of the invention in which a direct current is obtained at the electrodes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In FIG. 1, the device according to the invention is designated by the reference number 1. The device 1 comprises a housing 3 made of mild steel plates and supplied with a refractory material 2 to form a melting vessel 11. A refractory material suitable for the invention is found to be magnesium spinel in an Al2O3 matrix, this material being known as sintered refractory concrete. Corundum bricks are also suitable as refractory material. The phosphate slag melt 4 is placed in the housing as an iron oxide-containing and phosphate-containing material. The feed device 5 of the device 1 penetrates the housing 3 with a first tube 6. An aluminum carrier 7 containing metallic aluminum or an Al2O3 carrier can be fed through the first tube 6 of the feed device 5, which is achieved by a conveying device 8 in the form of a screw conveyor. The feed device 5 is immersed in the phosphate slag melt 4, so that the aluminum carriers 7 reach directly into the depth of the phosphate slag melt, where they melt together with the iron oxide and phosphate-containing materials, i.e. the phosphate slag melt 4, and are rapidly converted into elemental phosphorus and iron. The phosphorus is extracted via the extraction device 9, and the iron collects on the bottom surface 10 of the melting vessel 11, where it can be extracted. The phosphate slag melt 4 is converted into a phosphate-free cement slag without the addition of further starting materials.

[0041] In Fig. 2, identical parts are marked with identical reference numerals. The device 1 according to Fig. 2 has a cathode body 15 arranged below the aluminum-containing phosphate slag melt 4, a plurality of anode bodies 13 immersed in the aluminum-containing phosphate slag melt 4, the cathode body 15 being formed by a tin bath. In this case, the tin bath is arranged in a recess 14 in the bottom surface 10 of the melting vessel 11 and is undercoated by the iron formed as the reaction progresses. The tin bath is contained in a graphite body 18 located in the recess. The formation of an iron layer below the cathode body 15 is designated by reference numeral 12. An electric current is then introduced through the graphite body 18, the iron layer 12 and the tin bath 15. The anode body 13 may be made of graphite or high-alloy steel and may be provided with a coating 16.

[0042] The cathode bodies 15 are arranged in a first zone A of the melting vessel 11, which is separated from a second zone B laterally spaced from zone A by a dividing wall 16a immersed in the phosphate slag melt 4. Elemental phosphorus in the form of P2 is extracted in an extraction device 9, and in the case of coated anode bodies, oxygen (O2) escapes in a further extraction device 17 leading to the second zone B. A direct current is applied to the cathodes and anodes in a known manner.

[0043] The feeding device 5 has, according to Fig. 3, a first tube 6 penetrating the housing 3, in which a second tube 19 is arranged concentrically with the first tube 6 and forming an annular gap 20. The first tube 6 projects beyond the second tube 19 and penetrates the housing 3 at its end 6a. The two solid components, i.e. the iron oxide and phosphate-containing material 21 and the starting material 21 respectively, and the aluminum carrier 7, which is metallic aluminum in this case and is fed together into the device, come into contact with each other, which causes the formation of an autothermally sustained reaction front 22, in which the aluminum carrier 7 melts together with the iron oxide and phosphate-containing material 21. The resulting phosphate slag melt 4 contains aluminum, the aluminum oxide being represented by droplets, which enter the interior of the melting vessel and the already present phosphate slag melt, where their complete conversion into elemental iron and phosphorus takes place. In the region of the end 6 a of the second tube 6 an ignition device 23 may be provided for the aluminium support 7 and the iron oxide and phosphate containing material 21 .

[0044] In the embodiment shown in FIG. 4, the anode body 13 is arranged around the first tube 6 of the supply device 5 and means are provided for obtaining a direct current from the cathode body 15 and the anode body 13 . In relation to the present invention, the following is further disclosed: [1] 1. A process for separating elemental phosphorus from iron oxide-containing and phosphate-containing materials, in particular from waste materials such as sewage sludge (ash), animal meal, bone meal and / or steel mill slag, preferably together with materials such as apatite, phosphate rock and / or phosphorite, comprising the steps of: At least the following steps: Providing at least one iron oxide and phosphate containing material; adding at least one aluminum support to the at least one iron oxide and phosphate containing material and melting the at least one aluminum support with the at least one iron oxide and phosphate containing material to form an aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4); The aluminum-containing and optionally alumina-containing phosphate slag melt is mixed with the gaseous elements phosphorus, iron and Al in a melting vessel (11). 2 O 3 reacting the contained slag; Extract gaseous elemental phosphorus, iron and Al 2 O 3 Extracting the contained slag; The above method. [2] 10. The method according to claim 1, characterized in that at least one iron oxide- and phosphate-containing material (21) is provided as a phosphate slag melt (4) in a melting vessel (11) and at least one aluminum support (7) is added to the phosphate slag melt (4). [3] 1. The method according to claim 1, characterized in that a solid material, in particular sewage sludge ash with lime support and / or apatite and / or phosphate rock, is provided as iron oxide and phosphate-containing material (21) and solid metallic aluminum is added as at least one aluminum support (7). [4] Al 2 O 3 3. The method according to claim 1, wherein a support is added to the aluminum-containing and optionally alumina-containing phosphate slag melt (4). [5] Basicity (CaO / SiO ) of Aluminum-Containing and Possibly Aluminum Oxide-Containing Phosphate Slag Melts (4) 2 ) is preferably a CaO support and / or SiO 2 The method according to any one of [1] to [4], characterized in that the value is adjusted to 0.65 to 1.4, preferably 0.85 to 1.2, and more preferably 1, by adding a carrier. [6] The method according to any of the items [1] to [5], characterized in that a tin bath is arranged as a cathode body (15) in the melting vessel (11) below the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4) and at least one anode body (13), preferably of graphite, platinum or magnetite spinel, is arranged so as to be immersed in the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4). [7] The method according to [6], characterized in that a direct current, preferably between 3V and 15V, preferably between 6V and 12V, more preferably between 8V and 10V, is applied to the cathode body and the anode body. [8] The method according to [6], characterized in that a direct current is obtained from a cathode body (15) and an anode body (13). [9] 10. The method according to any of claims 6 to 8, characterized in that the cathode body (15) is arranged in a first area (A) of the melting vessel (11) in a recess (14) arranged in a partial area of ​​the bottom surface (10) of the melting vessel (11) and that at least one anode body (13) is arranged in a second area (B) of the melting vessel (11) different from the first area (A), and that gaseous phosphorus is withdrawn from the first area (A) and oxygen is withdrawn from the second area (B).

[10] A device for carrying out the method according to any of [1] to [9], comprising a melting vessel (11) formed by a refractory-lined housing (3), a phosphate slag melt (4) containing aluminum and optionally aluminum oxide arranged in the melting vessel (11), a gas chamber closed by the housing (3) above the phosphate slag melt (4), as well as a feed device (5) for iron oxide and phosphate-containing material (21) and at least one discharge device (9) for gaseous elemental phosphorus.

[11] The device according to

[10] , characterized in that the feed device (5) comprises a first tube (6) passing through the housing (3) in which a conveying device (8), preferably in the form of a screw conveyor, for at least one aluminium carrier (7) is arranged.

[12] 10. The device according to claim 10, characterized in that the supply device (5) comprises a first tube (6) passing through the housing (3) in which a second tube (19) is arranged, preferably forming an annular gap (20) concentric with the first tube (6), one of the first tube (6) and the second tube (19) designed to supply the iron oxide and phosphate containing material (21) and the other of the first tube (6) and the second tube (19) designed to supply the aluminum support (7), the first tube (6) protruding beyond the second tube (19) and penetrating into the housing (3) at its end (6a).

[13] The device according to any one of

[10] to

[12] , characterized in that the device (1) has a cathode body (15) arranged under the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4) and at least one anode body (13) immersed in the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4).

[14] 10. The device according to claim 9, characterized in that the cathode body (15) is arranged in a first region (A) of the melting vessel (11) in a recess (14) arranged in the bottom surface (10) of the melting vessel (11) and that at least one anode body (13) is arranged in a second region (B) of the melting vessel (11) laterally spaced from the first region (A), and a further discharge device (17) is arranged in the second region (B).

[15] The device according to

[14] , characterized in that between the first region (A) and the second region (B), a dividing wall (16a) dividing the gas space into two sections separated from each other is immersed in the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4).

[16] The device according to any one of

[13] to

[15] , characterized in that the cathode body (15) is formed from a tin bath.

[17] The device according to

[16] , characterized in that the tin bath is contained in a carbon containing body (18) arranged in a recess (14).

[18] The device according to any one of

[13] to

[15] , characterized in that at least one anode body (13) is made of graphite, platinum or magnetite spinel.

[19] The device according to any one of

[13] to

[15] , characterized in that at least one anode body (13) is made of high alloy steel, the steel being preferably coated with platinum (16).

[20] 19. The device according to any of the claims

[13] to

[19] , characterized in that at least one anode body (13) is designed to be coolable, preferably by means of channels arranged inside the anode body (13) for a tin melt, a salt melt or a sodium melt or for gas cooling, preferably with nitrogen or argon.

[21] The device according to any one of

[13] to

[20] , characterized in that the device (1) comprises means for applying a direct current to the cathode body (15) and to the anode body (13).

[22] A device according to any of the claims

[13] to

[21] , characterized in that the device (1) comprises means for obtaining a direct current from the cathode body (15) and from the anode body (13).

Claims

1. A method for separating elemental phosphorus from an iron oxide-containing and phosphate-containing material, comprising at least the following steps: Providing at least one iron oxide and phosphate containing material; adding at least one aluminum support to the at least one iron oxide and phosphate containing material and melting the at least one aluminum support together with the at least one iron oxide and phosphate containing material to form an aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4); The aluminum-containing and optionally aluminum oxide-containing phosphate slag melt is mixed with the gaseous elements phosphorus, iron and Al in a melting vessel (11). ２ O ３ reacting the contained slag; Gaseous elemental phosphorus is extracted, and iron and Al are extracted. ２ O ３ Extracting the contained slag; Including, The method according to claim 1, characterized in that the tin bath is arranged as a cathode body (15) below the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4) in the melting vessel (11), at least one anode body (13) is arranged so as to be immersed in the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4), and a direct current is applied to the cathode body and the anode body or a direct current is obtained from the cathode body (15) and from the anode body (13).

2. 2. The method according to claim 1, characterized in that at least one iron oxide- and phosphate-containing material (21) is provided as a phosphate slag melt (4) in a melting vessel (11) and at least one aluminum support (7) is added to the phosphate slag melt (4).

3. 2. The method according to claim 1, characterized in that a solid material is provided as iron oxide and phosphate-containing material (21) and solid metallic aluminum is added as at least one aluminum support (7).

4. A ２ O ３ 4. The method according to claim 1, wherein a support is added to the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4).

5. The aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4) is ２ 4. The process according to claim 1 , wherein the basicity, weight ratio, is adjusted to a value between 0.65 and 1.

4.

6. 4. The method according to claim 1, characterized in that the cathode body (15) is arranged in a first area (A) of the melting vessel (11) in a recess (14) arranged in a partial area of ​​the bottom surface (10) of the melting vessel (11) and that at least one anode body (13) is arranged in a second area (B) of the melting vessel (11) different from the first area (A), and that gaseous phosphorus is withdrawn from the first area (A) and oxygen is withdrawn from the second area (B).

7. 4. A device for carrying out the method according to claim 1, comprising a melting vessel (11) formed by a refractory-lined housing (3), a phosphate slag melt (4) containing aluminum and optionally aluminum oxide arranged in the melting vessel (11), a gas chamber closed by the housing (3) above the phosphate slag melt (4), as well as a feed device (5) for iron oxide- and phosphate-containing material (21) and at least one extraction device (9) for gaseous elemental phosphorus, characterized in that the device (1) comprises a cathode body (15) arranged below the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4) and at least one anode body (13) immersed in the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4).

8. 8. The device according to claim 7, characterized in that the supply device (5) comprises a first tube (6) passing through the housing (3) and in which the conveying device (8) is arranged.

9. 8. The device according to claim 7, characterized in that the supply device (5) comprises a first tube (6) passing through the housing (3) in which a second tube (19) is arranged and forms an annular gap (20), one of the first tube (6) and the second tube (19) is designed to supply the iron oxide and phosphate-containing material (21) and the other of the first tube (6) and the second tube (19) is designed to supply the aluminum support (7), the first tube (6) protruding beyond the second tube (19) and penetrating the housing (3) at its end (6a).

10. 8. The device according to claim 7, characterized in that the cathode body (15) is arranged in a first region (A) of the melting vessel (11) in a recess (14) arranged in the bottom surface (10) of the melting vessel (11) and that at least one anode body (13) is arranged in a second region (B) of the melting vessel (11) laterally spaced from the first region (A), and a further extraction device (17) is arranged in the second region (B).

11. 11. The device according to claim 10, characterized in that between the first area (A) and the second area (B), a dividing wall (16a) dividing the gas space into two sections separated from each other is immersed in the aluminum-containing and optionally aluminum oxide-containing phosphate slag melt (4).

12. 8. The device according to claim 7, characterized in that the cathode body (15) is formed from a tin bath.

13. 13. The device according to claim 12, characterized in that the tin bath is contained in a carbon containing body (18) arranged in the recess (14).

14. 8. A device according to claim 7, characterized in that at least one anode body (13) is made of graphite, platinum or magnetite spinel.

15. 8. A device according to claim 7, characterized in that at least one anode body (13) is made of high alloy steel.

16. 8. Device according to claim 7, characterized in that at least one anode body (13) is designed to be coolable.

17. 8. A device according to claim 7, characterized in that the device (1) comprises means for applying a direct current to the cathode body (15) and to the anode body (13).

18. 8. A device according to claim 7, characterized in that the device (1) comprises means for obtaining a direct current from the cathode body (15) and from the anode body (13).

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