WO2013157694A1 - Method and apparatus for recovering silicon from slag - Google Patents

Abstract

The present invention provides a method for recovering silicon from slag. The method comprises the steps of: preparing a reaction container comprising a material capable of enduring a high temperature environment of a temperature range at which slag melts and showing acid stability; injecting slag and a deoxidizing agent into the reaction container to mix the same; heating the reaction container to melt the slag so as to oxidize the deoxidizing agent and to reduce silicon from the slag; cooling the reaction container; injecting an acid solution into the reaction container to dissolve slag, oxidized deoxidizing agent and non-oxidized deoxidizing agent except silicon by acid treatment; and recovering the silicon by filtering.

Description

 【Specification】

 [Name of invention]

 Method and apparatus for recovering silicon from slag

 Technical Field

 The present invention relates to a method for recovering silicon, and more particularly, to a method and apparatus for economically recovering silicon from slag.

 Background Art

The steel industry consumes large quantities of raw materials and energy to produce steel, and generates large quantities of various by-products and wastes through a complex production system of raw materials, steelmaking, steelmaking, and rolling. These by-products and waste account for 65% of the main product, steel. About 80% of this solid by-product and waste is slag, the remainder in the form of dust or sludge. Metallurgical slag is typically produced in steel smelting process, and is an industrial by-product other than iron generated in blast furnaces, converters, and electric furnaces, and is classified into blast furnace slag generated in blast furnace process and steel slag generated in steelmaking process. Blast furnace slag is often derived from impurities of iron ore, reducing coke, and lime. The main components are silicon and calcium oxide. At present, the world's crude steel production amounted to about 1 billion lons per year, which varies depending on the country's crude steel technology. However, blast furnace slag produces about 300kg per tonne of crude steel and steel slag produces about 170kg of slag. Therefore, steel slag output can be estimated to be at least about 500 million tons. In Korea, the generation of POSCO accounts for more than 80% of the combined amount of blast furnace slag and steelmaking slag (electric converter). However, the amount of slag generated in Korea is rapidly increasing as Hyundai Steel also promotes an integrated steelmaking process. Given these enormous current outputs and future increases, eco-friendly research and investment in the treatment and use of metal smelting slags is an urgent and essential part of the stable development of the steel industry. Can be. Currently, blast furnace slag is recycled to fine aggregates and fine powders for cement and concrete, but almost all of steel slag is used as a simple landfill for filling or road aggregates. This is because the chemical composition of steelmaking slag is very different from that of blast furnace slag, making it difficult to use as a cement and the use of concrete aggregates as a result of the high glass lime contained in steelmaking slag. However, despite such problems, there is a lack of research or investment for new application development or product development. On the other hand, a technique for recovering silica from the slag is disclosed, for example, in Patent No. 10-1088901. However, this technique recovers Si02 from slag and reduces Si02 to Si using C. At this time, the reduction process by C should be carried out at a high temperature of about 2000 ^° C or more, so economic efficiency is low. In addition, even if high purity silica is recovered by acid treatment, silicon is contaminated again by impurities contained in C upon reduction by C, and therefore, an additional process must be performed. In addition, a process using trichlorosilane is carried out (also called the Siemens process), which is expensive because of the gas phase method, and the production rate of silicon is very slow. In addition, there is an environmental problem due to the use of silane chloride.

 [Detailed Description of the Invention]

 [Technical problem]

 The present invention is to solve the above-mentioned problems in the prior art, to provide a method for recovering the silicon from the slag in a simple process.

 Another object of the present invention is to provide a method for recovering silicon from slag economically at lower temperatures compared to the prior art of reducing silica using carbon.

 It is yet another object of the present invention to provide a method for recovering silicon from metal smelting waste without causing legal and technical special environmental problems in recovering silicon. Another object of the present invention is to provide a silicon recovery apparatus capable of performing the above method.

 [Technical solution]

In order to achieve the above object, according to the present invention there is provided a method for recovering silicon from slag, the method comprising a reaction container made of a material that can withstand a high silver environment in the temperature range in which the slag is melted and exhibits stability against acids And preparing and mixing slag and a deoxidizer in the reaction vessel, and heating the reaction vessel to melt the slag to oxidize the deoxidizer and reduce silicon from the slag. Cooling the reaction vessel, adding an acid solution to the reaction vessel, performing an acid treatment step of dissolving slag, oxidized deoxidizer, and non-oxidized deoxidizer, except for silicon; It is characterized in that it comprises the step of recovering the silicon. In one embodiment, the reaction vessel may be made of carbon, AI2O3 or MgO crucible. In one embodiment, the deoxidizer may be a deoxidizer having a higher oxidation degree than silicon. In one embodiment, the deoxidizer may be at least one deoxidizer selected from Al, Ca and Mg. In one embodiment, the deoxidizer may be mixed with the slag is added to the increase ratio of 0.1 to 2 relative to the slag. In one embodiment, the reaction vessel may be heated to a temperature of about 1500 ° C. In one embodiment, the heating of the reaction vessel, reaction of the slag of oxygen by the reaction at the interface of the slag and deoxidizer is combined with the deoxidizer to oxidize the deoxidizer, the silica in the slag is reduced to silicon Can be. In one embodiment, the acid solution may be at least one acid solution selected from hydrochloric acid, nitric acid, sulfuric acid and aqua regia. In one embodiment, silicon deposition impurities may also be removed in an ionic state by the interface reaction between the acid solution and silicon.

In one embodiment, the acid treatment may be performed in a reaction vessel for a time of 30 minutes or more and 24 hours or less, preferably for 30 minutes or more and 3 to 4 hours. According to another aspect of the present invention, there is provided a silicon recovery device for recovering silicon from the slag, the device is installed in the reaction chamber containing the reaction vessel, the upper and lower ends of the reaction chamber, the inside of the reaction chamber outside Sealing means for controlling the atmosphere inside the reaction chamber by shielding from the atmosphere, Gas supply means for injecting an inert gas into the reaction chamber and discharge the inert gas from the chamber, and installed in the reaction chamber Heating means for heating a reaction vessel mounted in the tub, and mounted inside the reaction vessel, containing slag and deoxidizer, capable of withstanding high temperature environments in the temperature range in which the slag is melted and exhibiting stability against acids A reaction vessel made of material, and a thermocouple for measuring temperature And supplying an acid solution capable of dissolving slag, oxidized deoxidizer, and non-oxidized deoxidizer to supply the slag supply unit and deoxidizer supply unit for supplying a deoxidizer having a higher oxidation degree than slag and silicon to the reaction vessel. An acid solution supply unit, a filter device for separating the reduced silicon and the component melted by the acid solution, and a control unit for controlling the overall operation of the silicon recovery device, wherein the control unit uses the heating means. The reaction vessel may be heated to silver in which the slag is melted to melt the slag of the reaction vessel, thereby oxidizing the deoxidizer and reducing silicon from the slag. In one embodiment, the reaction vessel of the silicon recovery device may be composed of carbon, AI2O3 or MgO crucible. In one embodiment, the deoxidizer may be at least one deoxidizer selected from Al, Ca and Mg. In one embodiment, the control unit of the silicon recovery device may be configured to supply the deoxidizer from the deoxidizer supply unit to the reaction vessel in a weight ratio of 0.1 to 2 relative to the slag. In one embodiment, the control unit of the silicon recovery device may be configured to heat the reaction vessel to a temperature of about 1,500 ^° C using the heating means. In one embodiment, by heating the reaction vessel of the silicon recovery device, the oxygen in the slag is combined with the deoxidizer through reaction at the interface of the slag and the deoxidizer, the deoxidizer is oxidized, and the slag silica Can be reduced to silicon. In one embodiment, the acid solution may be at least one acid solution selected from hydrochloric acid, nitric acid, sulfuric acid, and aqua regia. In one embodiment, silicon deposition impurities may also be removed in an ionic state by the interface reaction between the acid solution and silicon. In one embodiment, the control unit of the silicon recovery device may be configured to perform the treatment with the acid solution for 30 minutes to 24 hours, preferably 30 minutes to 3 to 4 hours in the reaction vessel. Advantageous Effects

 According to the present invention, it is possible to economically recover silicon, which is currently used as a semiconductor and solar cell material, by using a refining method applying a metallurgical refining process from slag disposed as a by-product in the steelmaking / steelmaking process through a very simple process. In addition, the silicon recovery method is more cost-effective and easier to process than carbon reduction by conventional gas phase refining and quartzite, and can in principle eliminate the cause of environmental pollution. have

 [Brief Description of Drawings]

 1 is a view schematically showing the configuration of a silicon rare water device according to an embodiment of the present invention.

 2A to 2D show that after the slag reduction treatment using aluminum deoxidizer according to one embodiment of the present invention, the cross section is observed by SEM, and the amount of silicon is reduced.

 3A to 3D show each component of the cross-section before and after acid treatment after slag reduction using aluminum deoxidizer according to one embodiment of the present invention. Indicates that it is

 4 is a view showing the results of XRD analysis on the recovered silicon subjected to acid treatment after slag reduction using aluminum deoxidizer according to one embodiment of the present invention, observed through SEM before acid treatment. It is shown that the reducing metals can be removed to recover the almost pure Si.

 [Best form for implementation of the invention]

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. In the following description, the description of the technical configuration already well known in the art will be omitted. Even if this description is omitted, those skilled in the art will be able to easily understand the features of the present invention through the following description. 1 schematically shows the configuration of a silicon recovery apparatus according to an embodiment of the present invention. As shown, the silicon recovery apparatus of the present invention comprises a reaction chamber (i.e., a vessel containing slag and deoxidizer) 50 containing a semi-unglube 10 (in one embodiment of the invention, mullite). Rubber cap 20 (in one embodiment of the present invention, silicone) for controlling the atmosphere inside the reaction chamber by blocking the inside of the reaction chamber from the outside atmosphere. Lance 30 for injecting and discharging inert gas In one embodiment, consisting of A1203), the inlet / exhaust gas injected into and out of the reaction tube 10 through the lance, installed around the reaction chamber 10, in the reaction tube A heating element 40 (in one embodiment of the invention, a SiC heating element is used) that heats the reaction chamber 50 to be mounted, mounted inside the reaction chamber 10, and containing slag and deoxidizer in a predetermined ratio. Reaction vessel 50 (in one embodiment of the invention, consisting of carbon) and a thermocouple 60 for measuring temperature. In addition, although not specifically illustrated, the slag supply unit for supplying the slag and the deoxidizer to the semi-atomizer 50 and the deoxidizer supply unit (not shown) and the reaction solution for supplying an acid solution capable of dissolving the slag and the deoxidizer, etc. An acid solution supply unit (not shown), and a filter device (not shown) for separating the component and silicon dissolved by the acid solution are also included, and a control unit (not shown) for controlling the overall operation of the silicon recovery device. do. The control unit automatically controls the method according to the present invention under the control of the user as a whole operation and the operation of each component. Such a control unit may be implemented in hardware and / or software, and the implementation form is not particularly limited. Those skilled in the art, with reference to the contents disclosed herein, can configure a control unit for performing the method of the present invention, the description of the configuration method of such a control unit will be omitted. Using the device configured as described above, a method for recovering the silicon from the slag in detail as follows. As described in the prior art, for example, in the case of manufacturing silicon for solar cells through the Siemens meteorological method and metallurgical method using silica ore, economical efficiency is not secured. In view of the problems of the prior art, the present invention provides a recovery technology of high-purity silicon that simultaneously realizes economic efficiency and production efficiency, that is, it is possible to economically recover silicon from metal smelting slag which is a by-product produced through steelmaking and steelmaking processes. Present the way. The present invention provides a method for economically recovering silicon from slag using oxidation / reduction reaction. Specifically, first, the slag and the deoxidizer are mixed with the reaction container 50 by mixing. At this time, as the deoxidizer, a deoxidizer having a higher oxidation degree than silicon, such as Al, Mg, Ca, or the like is used. The slag is then melted at a temperature such as, for example, one embodiment of the present invention, which is heated to a temperature of approximately 1,50 C to oxidize the deoxidizer and reduce the silicon. When heated, a reaction occurs at the slag and deoxidizer interface, oxygen in the slag is combined with the deoxidizer, and the deoxidizer is oxidized and the slag-rich silicon is reduced, i.e., the deoxidizer is more oxidized than silicon. Dew in conditions Combined with oxygen in lag, oxidized, and silica in the slag (Si02) is reduced to silicon. Meanwhile, in one embodiment of the present invention, the slag and the deoxidizer are mixed in an increase ratio of 1: 0.Γ 2. All. When the deoxidizer is added at a weight ratio smaller than αι, the reduction of silicon from the slag is not performed well, and when the deoxidizer is added at a weight ratio greater than 2, the reduction of the silicon is smooth but the economic efficiency is low. Add in weight ratio of .Γ 2. On the other hand, as described above, the redox reaction occurs at a very high temperature of about 1,500 ^° C. Therefore, the reaction container is preferably made of a material that withstands such a high temperature environment. In addition, as will be described later, the mixture is subjected to an acid treatment, and it is preferable to use a material having high stability against such an acid, that is, a material that does not significantly affect slag or deoxidizer contained in the reaction container. . In one embodiment of the invention, the reaction vessel is composed of carbon, A1203, MgO crucibles. After performing the oxidation / reduction reaction as above, the reaction vessel is cooled to a temperature of about 150 ° C. (natural cooling or forced cooling). Subsequently, a treatment for recovering the reduced silicon is performed. That is, one or more acid solutions selected from hydrochloric acid, nitric acid, sulfuric acid, and aqua regia (hydrochloric acid: nitric acid = 3: 1) are added to a reaction vessel in which slag, oxidized deoxidizer and reduced silicon are mixed. The slag is dissolved by the added acid solution, and the oxidized deoxidizer and the non-oxidized deoxidizer metal element except silicon are also dissolved. In addition, by the acid solution treatment, silicon dioxide impurities can be removed in an ionic state by the interface reaction between the acid solution and silicon. On the other hand, such acid solution treatment is carried out for 30 minutes or more and 24 hours or less, preferably 30 minutes or more and 3-4 hours. In other words, if the treatment with the acid solution is less than 30 minutes, the dissolution of impurities is not sufficient, and even if the acid solution is treated for 24 hours or more, the impurity removal effect is almost saturated. On the other hand, after the acid solution treatment for 3-4 hours, the effect of removing impurities does not increase significantly over time, so the acid solution treatment is carried out for 30 minutes or more and 24 hours or less, preferably for 30 minutes or more and 3-4 hours. After the above process, if the mixture solution is permeated through a suitable filter means or the filtering process is performed, the reduced silicon can be recovered. According to the conventional silicon recovery method, silica is reduced by using carbon. If you let

Although a high temperature of 2,000 r or more is required, according to the method of the present invention, it is possible to reduce the silicon even at a lower degree of silver, thereby ensuring economic efficiency. Also, using trichlorosilane Compared to the mens method, there is an advantage that can improve not only economic efficiency but also production speed. Hereinafter, the present invention will be described in detail through specific examples. A1 was added as a deoxidizer to the metal smelting slag, and heated to about 1,500 ° C. to oxidize A1 and to reduce silicon from silica in the aule slag. The slag in this state was observed using SEM, and the results are shown in Figures 2a to 2d. As shown in Figures 2a to 2d, the metal cross section was observed for each element, and each of them was again divided and marked, and as a result, it was confirmed that a significant amount of silicon was present in the reduced metal layer (Ca, Al, and some reductions). ). On the other hand, Figs. 3A to 3D show the samples before the subsequent acid treatment, and show that most of them are reduced to silicon although there are also calcium and aluminum (see Fig. 3B). The aqua regia was added to the reaction vessel containing the reduced metal and slag as described above and wet treatment was performed at 20 ^° C. for 1 hour. By this acid treatment, except for the reduced Si, the oxidized deoxidizer, slag, and impurities at the Si interface were dissolved. XRD analysis was performed on the recovered silicon after the acid treatment, and the results are shown in FIG. 4. As shown in FIG. 4, it was confirmed that Al, Ca, and the like remaining after the acid treatment among the reducing metals observed through the SEM before the acid treatment can be recovered to recover almost pure Si. It was confirmed that selective recovery of silicon was possible from the metal smelting slag. Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. That is, the embodiments may be variously modified and modified within the scope of the following claims, and they fall within the scope of the present invention. Accordingly, the invention is limited by the claims and their equivalents.

Claims

[Range of request]  [Claim 1]  As a method of recovering silicon from the slag,  Preparing a reaction vessel made of a material that can withstand high temperature environments in the temperature range in which the slag is melted and which is stable to acids;  Adding and mixing slag and deoxidizer into the reaction container;  Heating the reaction vessel to melt the slag to oxidize the deoxidizer and to reduce silicon from the slag;  Cooling the reaction vessel;  Adding an acid solution to the reaction vessel, performing an acid treatment step of dissolving slag, oxidized deoxidizer, and non-oxidized deoxidizer except silicon;  Performing a filtering process to recover the silicon  Method for recovering silicon from the slag comprising a.  [Claim 2] The method of claim 1 wherein the reaction vessel consists of carbon, A1 ₂ O ₃ or MgO crucible.  [Claim 3]  The method of claim 1, wherein the deoxidizer uses a deoxidizer having a higher oxidation degree than silicon.  [Claim 4]  The method of claim 3, wherein the deoxidizer is at least one deoxidizer selected from Al, Ca, and Mg additives.  [Claim 5]  The method for recovering silicon from slag according to any one of claims 1 to 3, wherein the deoxidizer is mixed with the slag by adding a weight ratio of 0.1 to 2 relative to the slag.  [Claim 6]  The method of claim 5, wherein the reaction vessel is heated to a temperature of about 1,50 ° C. 7.  [Claim 7] The method according to claim 6, wherein the reaction in the slag and the deoxidizer by the heating of the reaction vessel, oxygen in the slag is combined with the deoxidizer, the deoxidizer is oxidized, silica in the slag is reduced to silicon, characterized in that A method for recovering silicon from the slag. [Claim 8]  The method of claim 7, wherein the acid solution is at least one acid solution selected from hydrochloric acid, nitric acid, sulfuric acid, and aqua regia.  [Claim 9]  The method for recovering silicon from slag according to claim 8, wherein impurities in silicon are also removed in an ionic state by an interface reaction between the acid solution and silicon. [Claim 10]  10. The method of claim 9, wherein the acid treatment is carried out in a reaction vessel for 30 minutes to 24 hours.  [Claim 111]  The method of claim 10, wherein the acid treatment is performed in the reaction vessel for at least 30 minutes for 3 to 4 hours.  [Claim 12]  As a silicon recovery device for recovering silicon from the slag,  A reaction flow in which the reaction vessel is accommodated,  Sealing means is provided at the upper and lower ends of the reaction rib, the sealing means for controlling the atmosphere inside the reaction chamber by blocking the inside of the reaction rib from the outside atmosphere,  Gas supply means for injecting an inert gas into the reaction tube and discharging the inert gas from the rib;  Heating means installed around the reaction chamber to heat the reaction vessel mounted in the reaction chamber;  A reaction vessel mounted inside the reaction chamber, containing a slag and a deoxidizer, capable of withstanding a high temperature environment in the temperature range in which the slag is melted, and having a stability against acids;  Thermocouple for measuring temperature,  A slag supply unit and a deoxidizer supply unit for supplying a deoxidizer having a higher oxidation degree than slag and silicon to the semi-agitator;  An acid solution supply unit for supplying an acid solution capable of dissolving slag, oxidized deoxidizer, and non-oxidized deoxidizer except silicon;  Filter device for separating the molten component by the reduced silicon and the acid solution, and a control unit for controlling the overall operation of the silicon recovery device  Including The control unit uses the heating means to heat the reaction vessel to a temperature at which the slag is melted, to melt the slag in the reaction vessel to oxidize the deoxidizer and to remove the slag. And recover the silicon from the lag.  [Claim 13] The apparatus of claim 12, wherein the reaction vessel is comprised of carbon, A1 ₂ 0 _3, or MgO crucible.  [Claim 14]  The silicon recovery apparatus according to claim 12, wherein the deoxidizer is at least one deoxidizer selected from Al, Ca and Mg.  [Claim 15]  15. The silicon recovery apparatus according to any one of claims 12 to 14, wherein the control unit is configured to supply the deoxidizer from the deoxidizer supply unit to the reaction vessel at a weight ratio of 0.Γ2 relative to the slag.  [Claim 16]  The apparatus of claim 15, wherein the control unit is configured to heat the reaction vessel to a temperature of about 1,500 ° C. using the heating means.  [Claim 17]  The method according to claim 15, wherein by heating the reaction vessel, the oxygen in the slag is combined with the deoxidizer by the reaction at the interface between the slag and the deoxidizer, the deoxidizer is oxidized, the slag silica is reduced to silicon. A silicon recovery device.  [Claim 18]  18. The silicon recovery apparatus of claim 17, wherein the acid solution is at least one acid solution selected from hydrochloric acid, nitric acid, sulfuric acid, and aqua regia.  [Claim 19]  19. The silicon recovery apparatus according to claim 18, wherein silicon vapor impurities are also removed in an ionic state by an interface reaction between the acid solution and silicon.  [Claim 20]  20. The silicon recovery apparatus of claim 19, wherein the control unit is configured to perform the treatment with the acid solution for 30 minutes or more and 24 hours or less in the reaction vessel.  [Claim 21]  The apparatus of claim 20, wherein the control unit is configured to perform the treatment with the acid solution for at least 30 minutes for 3 to 4 hours in the reaction mixture.