Co-production process of granular silicon and white carbon black

Abstract

The invention provides a particle silicon and white carbon black co-production process, which comprises the following steps: step 1, inputting industrial silicon powder, hydrogen generated by a hydrogen production device and silicon tetrachloride STC into a circulating fluidized bed of a hydrogenation process according to a preset proportion, carrying out hydrogenation reaction to obtain trichlorosilane TCS, and sending the generated high-boiling residue to a slag slurry treatment process; step 2, feeding trichlorosilane (TCS) to a silane preparation process, and carrying out disproportionation reaction to obtain silicon tetrachloride (STC), trichlorosilane (TCS) and silane gas SiH4; wherein the trichlorosilane (TCS) is used for self-recycling in silane preparation; and step 3, sending the silicon tetrachloride STC to a white carbon black reaction process to obtain white carbon black, and sending the silane gas SiH4 to a granular silicon production process to obtain granular silicon.

Description

TECHNICAL FIELD

[0001] The present application relates to a co-production process, in particular a co-production process of granular silicon and white carbon black. BACKGROUND

[0002] This section provides background information only and can contain information that is not prior art.

[0003] In the prior art, a certain scale of granular silicon project is built separately, and various facilities such as hydrogen production station, cold hydrogenation, silane gas preparation, granular silicon device, post-processing / packaging, tail gas treatment, desalted water station, air separation nitrogen, circulating water station, boiler room and other supporting facilities are built to produce. The process flow is that hydrogen, industrial silicon powder and silicon tetrachloride are mixed in a certain proportion into a cold hydrogenation circulating fluidized bed to produce trichlorosilane, dichlorosilane and unreacted silicon tetrachloride, hydrogen and fine silicon powder. After treatment by a rectifying column, dichlorosilane, trichlorosilane and silicon tetrachloride are purified respectively, trichlorosilane enters the silane gas preparation process to generate dichlorosilane and silicon tetrachloride by disproportionation reaction, dichlorosilane produces silane gas by disproportionation reaction, and the purified silane gas enters the granular silicon process. More than 90% of the silane gas and hydrogen gas undergo homogeneous decomposition reaction in the granular silicon fluidized bed, and the silicon is deposited on the seed crystal surface and gradually grows to form granular silicon with a purity of more than 99.99999%. The formed granular silicon is discharged from the fluidized bed and subjected to post-processing / packaging before being sold as qualified products.

[0004] White carbon black (fumed silica) is an environmentally friendly and excellent performance additive, mainly used in rubber products (including high temperature vulcanized silicone rubber), textiles, papermaking, pesticides, food additive fields. The existing white carbon black project is built separately and the module is produced separately. The white carbon black production process gasifies silicon tetrachloride and monomethyltrichlorosilane (separately or proportionally) and then enters the reactor to react with compressed air and hydrogen at high temperature (about 1000℃) to generate a gas-solid mixture containing white carbon black, water vapor and hydrogen chloride. The mixture is separated by cyclone, and the solid white carbon black is deacidified, dried and packaged for sale. The acid-containing gas is dusted and absorbed to absorb the hydrogen chloride gas into by-product hydrochloric acid, which is stored and sold.

[0005] The existing granular silicon project and white carbon black project are built separately, and do not form a collaborative production, resulting in transportation and waste of water, electricity, raw materials and manpower.

[0006] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0007] The technical problem solved by the present application is to provide a cogeneration process of granular silicon and white carbon black.

[0008] To solve the above technical problem, the present application discloses a cogeneration process of granular silicon and white carbon black, comprising the following steps:

[0009] Step 1, input industrial silicon powder, hydrogen generated by a hydrogen production device and silicon tetrachloride STC into a circulating fluidized bed of a hydrogenation process according to a preset ratio, carry out a hydrogenation reaction, obtain trichlorosilane TCS, and send the generated high-boiling substance to a slag slurry treatment process;

[0010] Step 2, send the trichlorosilane TCS to a silane preparation process to carry out a disproportionation reaction, obtain silicon tetrachloride STC, trichlorosilane TCS and silane gas SiH4; wherein the trichlorosilane TCS is used for self-circulation of silane preparation;

[0011] Step 3, send the silicon tetrachloride STC to a white carbon black reaction process to obtain white carbon black, and send the silane gas SiH4 to a granular silicon production process to obtain granular silicon.

[0012] Further, the step 3 of sending the silane gas SiH4 to the granular silicon production process to obtain granular silicon comprises:

[0013] In the granular silicon production process, the silane gas SiH4 carries out a fluidization reaction to obtain granular silicon and hydrogen; wherein the hydrogen is sent to the white carbon black reaction process, and the granular silicon forms a product.

[0014] Further, the step 3 of sending the silicon tetrachloride STC to the white carbon black reaction process to obtain white carbon black comprises:

[0015] In the white carbon black reaction process, after the silicon tetrachloride STC and monomethyltrichlorosilane gasification, the mixture is mixed with compressed air and hydrogen, and enters a white carbon black reactor to carry out a high-temperature hydrolysis reaction to generate a gas-solid mixture including white carbon black, water vapor and hydrogen chloride gas;

[0016] The gas-solid mixture is subjected to cyclone separation to obtain solid white carbon black and acid-containing gas; wherein the solid white carbon black is subjected to deacidification and drying to form a product, and the acid-containing gas is subjected to dust removal, absorption and a hydrochloric acid resolution process to generate hydrogen chloride gas, which is used in the slag slurry treatment process.

[0017] Further, in the slag slurry treatment process of the step 1, the high-boiling substance, hydrogen chloride and catalyst are mixed according to a preset ratio, and are subjected to concentration and rectification processes to generate waste slag, waste gas and silicon tetrachloride STC; wherein the silicon tetrachloride STC is sent to the white carbon black reaction process.

[0018] Further, in the slag slurry treatment process, the waste slag is sent to the subsequent wastewater treatment process after hydrolysis reaction in the hydrolysis tank; the waste gas is sent to the tail gas treatment process, and the qualified gas after spraying in the leaching tower is discharged, and the wastewater generated at this time is sent to the wastewater treatment process.

[0019] Further, the silicon tetrachloride STC obtained in the silane preparation process in step 2 and the hydrogen obtained in the granular silicon production process are also sent to the hydrogenation process.

[0020] Further, the silicon tetrachloride STC obtained in the slag slurry treatment process is also sent to the hydrogenation process.

[0021] Further, a desalination water station is used to produce high-purity water for the hydrogen production device, and the circulating water generated at the same time is used for circulating cooling and temperature reduction in the white carbon black reaction process.

[0022] Further, the waste heat saturated steam generated in the white carbon black reaction process is used in the granular silicon production process.

[0023] Further, the wastewater treatment process receives the wastewater from the hydrochloric acid resolution process, the slag slurry treatment process and the tail gas treatment process, and the recovered water obtained after treatment is sent to the lime milk preparation and slag slurry treatment process for recycling, and the remaining part is concentrated and crystallized to generate crystalline salt.

[0024] Beneficial effects:

[0025] The cogeneration process of granular silicon and white carbon black provided by the application fundamentally solves the transportation and waste of energy sources such as water source, power, raw materials and manpower.

[0026] 1. The granular silicon production is prepared by cold hydrogenation technology to prepare trichlorosilane, and then silane gas is prepared, and the silane gas is decomposed to generate granular polycrystalline silicon, and in the process, trichlorosilane is disulfurized to generate silicon tetrachloride for producing white carbon black.

[0027] 2. The combustion hydrogen gas required in the white carbon black production process can be provided by the hydrogen gas generated in the granular silicon production (which can also be introduced from the hydrogen production station), and the compressed air required can be shared with the granular silicon production, thereby saving the investment of the white carbon black production facility.

[0028] 3. The high-temperature heat exchange medium circulating water in the white carbon black reaction process can be supplemented by the water source of the granular silicon desalination water station, thereby saving the investment of the white carbon black water station, and the nitrogen gas and instrument gas used by the white carbon black can share the product gas in the air separation nitrogen of the granular silicon, thereby saving the construction investment of the air compression station.

[0029] 4. The saturated steam generated in the silica reaction process can be used to supplement the steam heat source of granular silicon, reducing the investment in granular silicon steam generators. The wastewater produced by silica production can be discharged to the granular silicon wastewater treatment station for treatment to achieve zero wastewater discharge and reduce the construction investment of silica wastewater treatment stations.

[0030] 5. The acidic gas produced in the white carbon black reaction process is dust-removed and absorbed, and the hydrogen chloride gas is absorbed to become by-product hydrochloric acid. The hydrogen chloride gas is then generated through the hydrochloric acid analysis process and used for slurry treatment in the granular silicon project. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0032] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0033] The present invention provides a co-production process for granular silicon and white carbon black, which fundamentally solves the transportation and waste of energy such as water, electricity, raw materials, and manpower. The present invention adopts the FBR production process and the white carbon black reactor as the main equipment to produce granular silicon and nano-silicon. It is designed in accordance with the 51st item "Advanced Various Solar Photovoltaic Cells and High-Purity Silicon Materials" of the 28th item "Information Industry" in the "Guiding Catalogue for Industrial Structure Adjustment (2019 Edition)" and meets the condition of less than 70KWh / kg of comprehensive power consumption of new polysilicon projects in the "Standard Conditions for Photovoltaic Manufacturing Industry (2021 Edition)".

[0034] The present invention designs a granular silicon production line, a white carbon black production line and its supporting testing center, desalted water station, air separation nitrogen production, circulating water station, refrigeration station, wastewater treatment station and other facilities. The main facilities of the production line include: hydrogen production, cold hydrogenation, silane gas preparation, granular silicon, post-processing / packaging, slurry treatment, tail gas treatment, hydrochloric acid analysis, raw material workshop, white carbon black production workshop, and white carbon black packaging workshop.

[0035] The overall concept of the present invention is as follows:

[0036] 1. Granular silicon production is to prepare trichlorosilane through cold hydrogenation technology, and then prepare silane gas. The silane gas decomposes to produce granular polysilicon. In the process, trichlorosilane is disproportionated to produce silicon tetrachloride for the production of white carbon black.

[0037] 2. The combustion hydrogen required in the production of silica can be provided by the hydrogen produced by granular silicon production (or can be introduced from a hydrogen production station), and the compressed air required can be shared with granular silicon production, eliminating the investment in building separate facilities for silica production.

[0038] 3. The high-temperature heat exchange medium circulating water in the silica reaction process can be supplemented by the water source of the granular silicon desalted water station, eliminating the investment in the silica water station. The nitrogen and instrument gas used by silica can share the product gas in the air separation nitrogen production of granular silicon, eliminating the construction investment of the air compressor station.

[0039] 4. The saturated steam generated in the silica reaction process can be used to supplement the steam heat source of granular silicon, reducing the investment in granular silicon steam generators. The wastewater produced by silica production can be discharged to the granular silicon wastewater treatment station for treatment to achieve zero wastewater discharge and reduce the construction investment of silica wastewater treatment stations.

[0040] 5. The acidic gas produced in the white carbon black reaction process is dust-removed and absorbed, and then undergoes a hydrochloric acid analysis process to generate hydrogen chloride gas, which is used for slurry treatment in the granular silicon project.

[0041] like Figure 1 As shown, the overall technical solution of the present invention is as follows:

[0042] Industrial silicon powder, hydrogen produced by hydrogen production, and silicon tetrachloride (STC) are fed into a circulating fluidized bed for hydrogenation in a certain proportion, where a hydrogenation reaction occurs:

[0043] 3SiCL4+Si+2H2→4SiHCL3

[0044] The produced trichlorosilane (TCS) is sent to silane preparation, where a disproportionation reaction occurs:

[0045] 2SiHCL3→SiH2CL2+SiCL4

[0046] 3SiH2CL2→SiH4+2SiHCL3

[0047] The generated silicon tetrachloride (STC) is sent to the white carbon black reaction process for utilization, the generated trichlorosilane (TCS) is recycled, and the generated silane gas (SiH4) is sent to granular silicon, where the silane gas (SiH4) undergoes a fluidization reaction:

[0048] SiH4→Si+2H2

[0049] Silicon is deposited irregularly on the surface of the seed crystal and gradually grows to form granular silicon that meets the requirements of the finished product. The hydrogen can be sent to the silica reaction process for utilization; the granular silicon is sent to post-processing / packaging for finished product air separation, dust removal, polishing and other processes, and then packaged into tons for sale.

[0050] The silicon tetrachloride (STC) produced in the preparation of silane is vaporized and enters the white carbon black reactor, and high-temperature hydrolysis reaction (about 1000℃) occurs with compressed air and hydrogen (from the fluidized reaction of granular silicon or a hydrogen production device), to generate a gas-solid mixture containing white carbon black, water vapor, hydrogen chloride, etc. The gas-solid mixture is separated by a cyclone, and the solid white carbon black is deacidified, dried and packaged for sale; the acid-containing gas is dedusted and absorbed, and hydrogen chloride gas is generated by a hydrochloric acid resolution process, which is used for slag slurry treatment in the granular silicon project.

[0051] In another embodiment of the present application, the high-boiling substance produced by hydrogenation is sent to slag slurry treatment, and the high-boiling substance, hydrogen chloride, and catalyst are mixed in a certain proportion for reaction. The silicon tetrachloride (STC) generated by concentration and rectification processes is sent to white carbon black or hydrogenation use.

[0052] The waste residue produced by slag slurry treatment is sent to hydrolysis tank for hydrolysis reaction, and then to wastewater treatment; the waste gas produced by slag slurry treatment is sent to tail gas treatment process, and then discharged after being sprayed by a washing tower; and the produced wastewater is sent to wastewater treatment.

[0053] In another embodiment of the present application, the silicon tetrachloride (STC) produced by disproportionation reaction in the preparation of silane can be returned to hydrogenation for recycling use in addition to being sent to the white carbon black process for reaction to prepare fumed silica.

[0054] In another embodiment of the present application, the hydrogen gas produced by granular silicon can be returned to hydrogenation for recycling use in addition to being sent to the white carbon black process for reaction to prepare fumed silica.

[0055] In another embodiment of the present application, the silicon tetrachloride (STC) returned from slag slurry high-boiling treatment can be returned to hydrogenation for recycling use in addition to being sent to the white carbon black process for reaction to prepare fumed silica.

[0056] In another embodiment of the present application, the high-purity water produced by the desalination water station is used for hydrogen production, and the circulating water is used for cooling in the white carbon black reaction process.

[0057] In another embodiment of the present application, the nitrogen gas and instrument gas produced by air separation are used as instrument gas and nitrogen gas for granular silicon and white carbon black (not shown in the figure).

[0058] In another embodiment of the present application, the waste heat saturated steam produced in the white carbon black reaction process is used for granular silicon.

[0059] In another embodiment of the present application, the wastewater treatment receives wastewater from hydrochloric acid resolution, slag slurry treatment, and tail gas treatment, and the treated wastewater is sent to lime milk preparation and slag slurry treatment for recycling use (not shown in the figure); and the wastewater is concentrated and crystallized to produce crystalline salt for sale.

[0060] In specific implementations, the present application provides a computer storage medium and a corresponding data processing unit, wherein the computer storage medium is capable of storing a computer program, and the computer program is executable to perform some or all steps of the invention content and each embodiment of the co-production process of particulate silicon and white carbon black when executed by the data processing unit. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), or the like.

[0061] Those skilled in the art can clearly understand that the technical solutions in the embodiments of the present application can be realized by means of a computer program and its corresponding general hardware platform. Based on such understanding, the technical solutions in the embodiments of the present application can be embodied in the form of a computer program, i.e., a software product, which can be stored in a storage medium and includes a plurality of instructions for causing a device (which can be a personal computer, a server, a single-chip microcomputer, an MCU, or a network device) containing a data processing unit to execute the method described in each embodiment or some parts of the embodiments of the present application.

[0062] The present application provides a co-production process of particulate silicon and white carbon black. There are many methods and approaches to realize the technical solutions, and the above description is only the preferred embodiment of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, some improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application. The components not explicitly described in the embodiments can be realized by using existing technologies.

Claims

1. A process for the co-production of granular silicon and white carbon black, characterized in that: The following steps are involved: Step 1: Industrial silicon powder, hydrogen generated by a hydrogen production device, and silicon tetrachloride (STC) are fed into a circulating fluidized bed in a hydrogenation process according to a preset ratio to produce trichlorosilane (TCS). The high-boiling substances produced are then fed to a slurry treatment process. Step 2: Send trichlorosilane TCS to the silane preparation process for disproportionation reaction to obtain silicon tetrachloride STC, trichlorosilane TCS and silane gas SiH4; wherein, trichlorosilane TCS is used for self-recycling in silane preparation; Step 3: Send silicon tetrachloride STC to the white carbon black reaction process to obtain white carbon black, and send silane gas SiH4 to the granular silicon production process to obtain granular silicon.

2. The process for co-production of granular silicon and white carbon black according to claim 1, characterized in that: The step 3 of delivering silane gas SiH4 to the granular silicon production process to obtain granular silicon includes: In the granular silicon production process, silane gas SiH4 undergoes a fluidized reaction to produce granular silicon and hydrogen; among them, the hydrogen is sent to the white carbon black reaction process, and the granular silicon is formed into a product.

3. The process for co-production of granular silicon and white carbon black according to claim 2, characterized in that: The step 3 of sending silicon tetrachloride STC to a white carbon black reaction process to obtain white carbon black comprises: In the silica reaction process, silicon tetrachloride (STC) and monomethyltrichlorosilane are gasified and then enter the silica reactor with compressed air and hydrogen to undergo a high-temperature hydrolysis reaction, generating a gas-solid mixture of silica, water vapor, and hydrogen chloride. The gas-solid mixture is separated by a cyclone to obtain solid silica and acid-containing gas; wherein the solid silica is deacidified and dried to form a product, and the acid-containing gas is subjected to dust removal, absorption and hydrochloric acid analysis to generate hydrogen chloride gas for use in the slurry treatment process.

4. The process for co-production of granular silicon and white carbon black according to claim 3, characterized in that: In the slurry treatment process described in step 1, high boiling points, hydrogen chloride and catalyst are mixed and reacted in a preset ratio, and then undergo concentration and distillation processes to generate waste residue, waste gas and silicon tetrachloride STC; wherein the silicon tetrachloride STC is sent to the white carbon black reaction process.

5. The process for co-production of granular silicon and white carbon black according to claim 4, characterized in that: In the slurry treatment process, the waste slag is sent to the subsequent wastewater treatment process after hydrolysis reaction in the hydrolysis tank; the waste gas is sent to the tail gas treatment process, and the gas that passes the spraying in the leaching tower is discharged to the outside, and the wastewater generated at this time is sent to the wastewater treatment process.

6. The process for co-production of granular silicon and white carbon black according to claim 3, characterized in that: The silicon tetrachloride STC obtained in the silane preparation process in step 2 and the hydrogen obtained in the granular silicon production process are also sent to the hydrogenation process for use.

7. The process for co-production of granular silicon and white carbon black according to claim 4, characterized in that: The silicon tetrachloride STC obtained in the slurry treatment step is also sent to the hydrogenation step for use.

8. The process for co-production of granular silicon and white carbon black according to claim 1, characterized in that: A desalted water station is used to generate high-purity water for use in the hydrogen production device, and the circulating water generated is supplied to the silica reaction process for circulation cooling and temperature reduction.

9. The process for co-production of granular silicon and white carbon black according to claim 1, characterized in that: The waste heat saturated steam generated by the white carbon black reaction process is used in the granular silicon production process.

10. The process for co-production of granular silicon and white carbon black according to claim 5, characterized in that: The wastewater treatment process receives wastewater from the hydrochloric acid analysis process, the slurry treatment process and the tail gas treatment process. The recycled water obtained after treatment is sent to the lime milk preparation and slurry treatment process for recycling. The remaining part is concentrated and crystallized to produce crystalline salt.

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