CN102161487B - Method for producing pure silicon by using by-product silica gel in phosphate fertilizer industry - Google Patents

Method for producing pure silicon by using by-product silica gel in phosphate fertilizer industry Download PDF

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CN102161487B
CN102161487B CN201110055472.3A CN201110055472A CN102161487B CN 102161487 B CN102161487 B CN 102161487B CN 201110055472 A CN201110055472 A CN 201110055472A CN 102161487 B CN102161487 B CN 102161487B
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silica gel
phosphate fertilizer
fertilizer industry
silicon
product
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CN102161487A (en
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明大增
李英翔
李志祥
李崇贵
李勇辉
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YUNTIANHUA INTERNATIONAL CHEMICAL INDUSTRY Co Ltd YUNNAN
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Abstract

The invention relates to a method for producing pure silicon by using by-product silica gel in a phosphate fertilizer industry, which belongs to the fields of inorganic chemical industry, resource comprehensive utilization of the by-product silica gel in the phosphate fertilizer industry and the production technology of pure silicon. In the method, pure silicon is produced from the by-product silica gel in the phosphate fertilizer industry, which is used as a silicon source, by a carbon thermal reduction method. The method comprises the following steps of: a. pretreatment of raw materials; b. material mixing; c. reaction; d. cooling; e. crushing; f. wet purification; g. washing with water to be neutral after the wet purification, and then drying; h. vacuum refining; and i. finally cooling. The invention takes the by-product silica gel in the phosphate fertilizer industry as the silicon source, develops a new product and a new technology of the resource comprehensive utilization of the by-product silica gel in the phosphate fertilizer industry; the method has the advantages of simple process, low cost, high purity and the like, not only is favorable for the environmental pollution control in the phosphate fertilizer industry, but also is favorable for the protection and effective utilization of silicon resource associated with phosphate ores. Meanwhile, the method also brings good social and economic benefits.

Description

A kind of method of producing pure silicon with product silica gel in phosphate fertilizer industry
Technical field
The invention belongs to field of inorganic chemical engineering, relate to a kind of method of producing pure silicon with product silica gel in phosphate fertilizer industry, relate to the production technical field of product silica gel in phosphate fertilizer industry comprehensive utilization of resources, pure silicon.
Background technology
Product silica gel in phosphate fertilizer industry, mainly from waste gas containing fluoride absorption process and utilize silicate fluoride solution to produce the course of processing of fluorochemical (Sodium Fluoride, Neutral ammonium fluoride, aluminum fluoride, sodium aluminum fluoride, hydrogen fluoride etc.).Along with the raising of China's Phosphate Fertilizer Industry fluorine recovery technology, the quantity discharged of product silica gel in phosphate fertilizer industry will certainly cause the wasting of resources and environmental pollution by increasing.
Silicon (
Figure 2011100554723100002DEST_PATH_IMAGE001
) material is the base mateiral of microelectronics industry and solar electrical energy generation, along with developing rapidly of photovoltaic industry, the demand of pure silicon sharply increases.Therefore, the research and development of pure silicon new preparation technology become the problem that people very pay close attention to.At present, the method for preparing pure silicon is more, and its silicon source mostly is silicon-dioxide, silicofluoride, silicon carbide, silicon nitride, silane and derivative thereof etc.Silicon is extremely wide in distributed in nature, in the earth's crust, approximately contain 25.8 %, mainly the form with silicon-dioxide and silicate exists, therefore, industrially conventionally take silica (its main component is silicon-dioxide) and make industrial silicon, as need obtain highly purified silicon, need to carry out further Refining processing.At present, take the method that silicon-dioxide prepares pure silicon as silicon source mainly contains: hot reducing method, fused salt electrolysis process etc.Wherein, according to the difference of reductive agent, hot reducing method can be divided into metallothermics, nonmetal heating reduction method etc.; According to the difference of eutectic fused salt, fused salt electrolysis process can be divided into electrolysis of fluorides method, electrolysis of chloride method etc.Wherein, the most representative is carbothermic method, electrolysis of chloride method.
I, carbothermic method: industrial, to contain
Figure 2011100554723100002DEST_PATH_IMAGE002
mineral (silica or quartzy etc.) be raw material, the Carbonaceous matter (charcoal, refinery coke, coal etc.) of take is reductive agent, in mineral hot furnace, melting makes industrial silicon, is commonly referred to carbothermic method or electric heating process.Complicated Si-O-C system consists of Si, O, tri-kinds of elements of C, mainly has SiO 2, SiO, Si, SiC, C, six kinds of materials of CO, side reaction is more, its principal reaction formula is:
Figure 2011100554723100002DEST_PATH_IMAGE003
(1.2-5)
The technological process of producing all can substantially be divided into raw material preparation, batching, melting, the ingot casting of coming out of the stove, product crushing packing, reclaim several parts such as silicon ash, and its technological process of production as shown in Figure 2.
The method is used for industrial production, and technique is relatively ripe, raw material be easy to get and cost lower, product purity is higher, silicone content can reach 97.00 %~99.00 % conventionally, but energy consumption is larger, belongs to high energy consumption industry.
II, electrolysis of chloride method: Toshiyuki Nohira in 2003 etc. adopt CaCl 2for molten salt system, by SiO 2direct Electrolysis makes pure silicon.This research group has carried out deep, systematic research to novel process afterwards, and further research and demonstration have been carried out in the aspects such as the feasibility of the method, mechanism, influence factor.
Experiment is found, take graphite as anode, adopts special negative electrode, by high-purity Si O 2be placed in two silicon single crystal plates, and use molybdenum filament tighten, during electrolysis, molybdenum filament does not immerse in ionogen, to avoid polluted product, in temperature, is that 1123 K, decomposition voltage are under the condition of 1.25 V, adopts CaCl 2for molten salt system, can be by SiO 2direct Electrolysis makes pure silicon, and its technical process as shown in Figure 3.Its electrode reaction is:
Anodic reaction:
Figure 2011100554723100002DEST_PATH_IMAGE004
(1)
Cathodic reaction:
Figure 2011100554723100002DEST_PATH_IMAGE005
(2)
Total reaction:
Figure 2011100554723100002DEST_PATH_IMAGE006
(3)
After electrolysis, negative electrode is placed under 1772 K and carries out vacuum-treat, utilize fusing point difference, make the Si and the SiO of electrolysis not of deposition 2separation, the purity of gained Si is about 99.80 %.
The method technique is simple, and production efficiency is high, and product purity is high, and cost is low, and energy consumption is little, good in economic efficiency, environmental friendliness, and potentiality are large, and prospect is good.Therefore, cause the common concern of various countries academia and industry member.
The major ingredient of product silica gel in phosphate fertilizer industry is silicon-dioxide, is the good raw materials of machine silicon series product: water glass, precipitated silica, 4A molecular sieve, δ type laminated crystal of sodium disilicate, metasilicate pentahydrate sodium etc.At present, utilize research and the relevant report of product silica gel in phosphate fertilizer industry production pure silicon less.2002, B.N. Mukashev etc. adopted thermit reduction, make Si-Al alloy, and further Refining obtains elemental silicon.But metallothermics is used for testing laboratory, its cost depends primarily on raw materials cost, and the price of aluminum metal powder is higher, resource efficiency is lower, and first makes Si-Al alloy Refining again, the burden that has increased Refining, economic benefit is not obvious, is difficult to realize industrialization.In addition, there is no other researchs and relevant report.
Because product silica gel in phosphate fertilizer industry output is huge, and fused salt electrolysis process is at present still in testing laboratory's exploratory stage, and throughput is limited, and therefore unrealized suitability for industrialized production, selects the relatively ripe carbothermic method of industrial manufacture process in test.
Summary of the invention
Object purport of the present invention overcomes deficiency of the prior art, provides a kind of technique simple, and cost is low, the method for producing pure silicon with product silica gel in phosphate fertilizer industry that purity is high.
For achieving the above object, the present invention adopts carbothermic method to produce pure silicon, and take charcoal, refinery coke is carbonaceous reducing agent, and its principal reaction is
Figure 2011100554723100002DEST_PATH_IMAGE007
, concrete technical scheme is as follows:
A. raw materials pretreatment: product silica gel in phosphate fertilizer industry is washed, is dried, after pre-treatment, dioxide-containing silica reaches 95%, by charcoal, refinery coke fragmentation, screening, dry, selecting granularity is charcoal, the refinery coke of 100~50 μ m, and its fixed carbon content reaches respectively 70-75% and 80-85%;
B. prepare burden: selecting granularity is the product silica gel in phosphate fertilizer industry of 150~75 μ m, and selecting granularity is charcoal, the refinery coke of 100~50 μ m, then with silica gel and charcoal, refinery coke, prepares burden, and mixes, and obtains mixture;
C. reaction: step b gained mixture is sent into pyrocarbon pipe furnace and preheat, the condition that preheats is for being evacuated to 5.0 * 10 -2below mbar, 1mbar=100Pa, is warming up to 500~700 ℃, and temperature rise rate is 25~50 ℃ of min -1, insulation 10~30min, protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02~0.04MPa, and shielding gas flow speed is 5.0~10.0CFH, 1CFH=472 cm 3min -1, pressure is 25~75mbar, is warming up to 1775~1825 ℃, temperature rise rate is 25~50 ℃ of min -1, insulation 20~30min;
D. cooling: adopt instrument to control cooling, reaction product can obtain silicon through cooling 6~8h to room temperature;
E. broken, silicon is crushed to suitable granularity 150~75 μ m;
F. wet purification: step e gained silicon is leached with leaching agent, purify;
G. after wet purification, wash with water to neutrality, dry;
H. vacuum refinement: under vacuum condition, refining, the purity of raising silicon;
I. cooling, product is cooled to room temperature, can obtain product.
Product silica gel in phosphate fertilizer industry described in step a is that phosphate fertilizer by-product fluosilicic acid is produced the silica gel of separating out in hydrofluoric acid, anhydrous hydrogen fluoride process, and dioxide-containing silica is 85-95%.
The pre-treatment of the product silica gel in phosphate fertilizer industry described in step a, i.e. wash conditions: liquid-solid ratio is 12: 1gml -1, washing time is 2h, stirring intensity is 300radmin -1, washing at least 3 times, its dioxide-containing silica can reach 95%; Drying conditions: 105 ± 5 ℃ of steady temperatures, dry 1~2h, dry number of times 1~2 time, to constant weight, its granularity is 150~75 μ m.
Charcoal described in step a, the pre-treatment of refinery coke, i.e. broken, screening condition: by after charcoal, refinery coke fragmentation, with standard sieve screening, obtain charcoal, refinery coke that granularity is 100~50 μ m; Drying conditions: 105 ± 5 ℃ of steady temperatures, dry 1~2h, dry number of times 1~2 time, to constant weight.
Batching described in step b, in material, the proportioning of C-Si is
Figure 2011100554723100002DEST_PATH_IMAGE008
, material charcoal-refinery coke proportioning be
Figure 2011100554723100002DEST_PATH_IMAGE009
.
The fragmentation of the pure silicon described in step e, is about to after charcoal, refinery coke fragmentation, with standard sieve screening, obtains the pure silicon that granularity is 150~75 μ m.
Wet purification described in step f, its processing condition: silicon particle size is D=150~75 μ m, and wet purification progression is two-stage, and leaching agent is followed successively by 8.00% HCl, 5.15% HF, and liquid-solid ratio is 5: 1, and stir speed (S.S.) is 140 radmin -1magnetic agitation, extraction temperature is 71.3 ℃, extraction time is 4h.
Being dried described in step h, its drying conditions is: 105 ± 5 ℃ of steady temperatures, dry 1~2h, dry number of times 1~2 time, to constant weight.
Vacuum refinement described in step I, its processing condition: adopt argon gas to make protection gas, vacuum tightness is that P=0.5Pa, refining temperature are that T=1500 ℃, refining time are 60min.
The described method of producing pure silicon with product silica gel in phosphate fertilizer industry, if conversion unit can meet reaction conditions, especially pressure, temperature of reaction etc., adopt pyrocarbon pipe furnace, graphite furnace etc. to be all fine, i.e. the present invention is not limited by device type.
The innovative point of producing the method for pure silicon with product silica gel in phosphate fertilizer industry of the present invention: from product silica gel in phosphate fertilizer industry comprehensive utilization angle, product silica gel in phosphate fertilizer industry comprehensive utilization of resources technology is mainly confined to white carbon black, silicate product at present, the limited space of further processing and utilization, added value is not high; And pure silicon is a ring of most critical in silicon development of chemical industry, the space of processing and utilization is larger, and added value is higher.At present, utilize research and the relevant report of product silica gel in phosphate fertilizer industry production pure silicon less.
Product silica gel in phosphate fertilizer industry described in the present invention, mainly from waste gas containing fluoride absorption process and utilize silicate fluoride solution to produce fluorochemical, as the course of processing of Sodium Fluoride, Neutral ammonium fluoride, aluminum fluoride, sodium aluminum fluoride, hydrogen fluoride etc.If can not effectively recycle product silica gel in phosphate fertilizer industry, will certainly cause the wasting of resources and environmental pollution; Otherwise, if can recycle fully by-product silica gel, will bring good Social benefit and economic benefit.Along with the raising of China's Phosphate Fertilizer Industry fluorine recovery technology, the quantity discharged of product silica gel in phosphate fertilizer industry is by increasing.Therefore, the development and utilization of product silica gel in phosphate fertilizer industry is imperative.The major ingredient of product silica gel in phosphate fertilizer industry is silicon-dioxide, is the good raw materials of machine silicon series product, and this point is similar to silica.Meanwhile, in product silica gel in phosphate fertilizer industry, the foreign matter content such as iron, aluminium, calcium, far below silica, has reduced the product burden of purifying; Through pre-treatment such as overpickling, washings, the foreign matter content in product silica gel in phosphate fertilizer industry reduces greatly.Therefore, product silica gel in phosphate fertilizer industry substantially meets pure silicon and produces the requirement to silicon source, and it is feasible utilizing product silica gel in phosphate fertilizer industry to produce pure silicon.
The present invention be take product silica gel in phosphate fertilizer industry as silicon source; product innovation, the new technology of product silica gel in phosphate fertilizer industry comprehensive utilization of resources have been developed; it is simple that described method has technique; cost is low; purity advantages of higher; not only be conducive to the environmental pollution improvement of Phosphate Fertilizer Industry, and be conducive to the protection of phosphorus ore association silicon resource and effectively utilize.Meanwhile, also good Social benefit and economic benefit will be brought.
Accompanying drawing explanation
Fig. 1 is process flow diagram of the present invention.
Fig. 2 is industrial silicon production process flow diagram.
Fig. 3 is CaCl 2molten salt system Direct Electrolysis solid SiO 2prepare pure silicon sketch.
Fig. 4 is that the XRD of the embodiment of the present invention 2 products obtained therefroms characterizes.
Fig. 5 is that the SEM of the embodiment of the present invention 2 products obtained therefroms characterizes.
Embodiment
below in conjunction with embodiment, the present invention is described further, but be not limited to embodiment.
embodiment 1
Raw material after pretreatment, according to material proportion (C-Si ratio) is
Figure 583172DEST_PATH_IMAGE008
, material proportion (charcoal-refinery coke ratio) is
Figure 375679DEST_PATH_IMAGE009
prepare burden; Mixture is sent into pyrocarbon pipe furnace, and the condition that preheats is for being evacuated to 5.0 * 10 -3mbar (1mbar=100Pa), is warming up to 600 ℃, and temperature rise rate is 50 ℃ of min -1, insulation 20min; Protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02MPa, and shielding gas flow speed is 7.5CFH (1CFH=472 cm 3min -1), pressure is 25mbar, is warming up to 1825 ℃, temperature rise rate is 50 ℃ of min -1, insulation 25min; Be cooled to room temperature, can obtain product.
embodiment 2
Raw material after pretreatment, according to material proportion (C-Si ratio) is , material proportion (charcoal-refinery coke ratio) is
Figure 301358DEST_PATH_IMAGE009
prepare burden; Mixture is sent into pyrocarbon pipe furnace, and the condition that preheats is for being evacuated to 5.0 * 10 -3mbar (1mbar=100Pa), is warming up to 600 ℃, and temperature rise rate is 50 ℃ of min -1, insulation 20min; Protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02MPa, and shielding gas flow speed is 7.5CFH (1CFH=472 cm 3min -1), pressure is 25mbar, is warming up to 1825 ℃, temperature rise rate is 50 ℃ of min -1, insulation 25min; Reaction product is cooling, after fragmentation, at silicon particle size, be D=150~75 μ m, wet purification progression is two-stage, leaching agent is followed successively by 8.00% HCl, 5.15% HF, liquid-solid ratio is 5: 1, stir speed (S.S.) is 140 radmin -1magnetic agitation, extraction temperature is 71.3 ℃, under the processing condition that extraction time is 4h, carries out wet purification; Washing, dry after, adopt argon gas to make protection gas, in vacuum tightness, be that P=0.5Pa, refining temperature are under T=1500 ℃, the refining time condition that is 60min, carry out vacuum refinement; Be cooled to room temperature, can obtain product.
embodiment 3
Raw material after pretreatment, according to material proportion (C-Si ratio) is , material proportion (charcoal-refinery coke ratio) is prepare burden; Mixture is sent into pyrocarbon pipe furnace, and the condition that preheats is for being evacuated to 5.0 * 10 -3mbar (1mbar=100Pa), is warming up to 500~700 ℃, and temperature rise rate is 25~50 ℃ of min -1, insulation 10~30min; Protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02MPa, and shielding gas flow speed is 7.5CFH (1CFH=472 cm 3min -1), pressure is 50mbar, is warming up to 1775 ℃, temperature rise rate is 50 ℃ of min -1, insulation 30min; Reaction product is cooling, after fragmentation, at silicon particle size, be D=150~75 μ m, wet purification progression is two-stage, leaching agent is followed successively by 8.00% HCl, 5.15% HF, liquid-solid ratio is 5: 1, stir speed (S.S.) is 140radmin -1magnetic agitation, extraction temperature is 71.3 ℃, under the processing condition that extraction time is 4h, carries out wet purification; Washing, dry after, adopt argon gas to make protection gas, in vacuum tightness, be that P=0.5Pa, refining temperature are under T=1500 ℃, the refining time condition that is 60min, carry out vacuum refinement; Be cooled to room temperature, can obtain product.
embodiment 4
Raw material after pretreatment, according to material proportion (C-Si ratio) is , material proportion (charcoal-refinery coke ratio) is
Figure 902661DEST_PATH_IMAGE009
prepare burden; Mixture is sent into pyrocarbon pipe furnace, and the condition that preheats is for being evacuated to 5.0 * 10 -3mbar (1mbar=100Pa), is warming up to 600 ℃, and temperature rise rate is 50 ℃ of min -1, insulation 20min; Protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02MPa, and shielding gas flow speed is 7.5CFH (1CFH=472 cm 3min -1), pressure is 50mbar, is warming up to 1800 ℃, temperature rise rate is 50 ℃ of min -1, insulation 25min; Reaction product is cooling, after fragmentation, at silicon particle size, be D=150~75 μ m, wet purification progression is two-stage, leaching agent is followed successively by 8.00% HCl, 5.15% HF, liquid-solid ratio is 5: 1, stir speed (S.S.) is 140 radmin -1magnetic agitation, extraction temperature is 71.3 ℃, under the processing condition that extraction time is 4h, carries out wet purification; Washing, dry after, adopt argon gas to make protection gas, in vacuum tightness, be that P=0.5Pa, refining temperature are under T=1500 ℃, the refining time condition that is 60min, carry out vacuum refinement; Be cooled to room temperature, can obtain product.
embodiment 5
Raw material after pretreatment, according to material proportion (C-Si ratio) is
Figure 443976DEST_PATH_IMAGE008
, material proportion (charcoal-refinery coke ratio) is prepare burden; Mixture is sent into pyrocarbon pipe furnace, and the condition that preheats is for being evacuated to 5.0 * 10 -3mbar (1mbar=100Pa), is warming up to 600 ℃, and temperature rise rate is 50 ℃ of min -1, insulation 20min; Protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02MPa, and shielding gas flow speed is 7.5CFH (1CFH=472 cm 3min -1), pressure is 75mbar, is warming up to 1800 ℃, temperature rise rate is 50 ℃ of min -1, insulation 20min; Reaction product is cooling, after fragmentation, at silicon particle size, be D=150~75 μ m, wet purification progression is two-stage, leaching agent is followed successively by 8.00% HCl, 5.15% HF, liquid-solid ratio is 5: 1, stir speed (S.S.) is 140 radmin -1magnetic agitation, extraction temperature is 71.3 ℃, under the processing condition that extraction time is 4h, carries out wet purification; Washing, dry after, adopt argon gas to make protection gas, in vacuum tightness, be that P=0.5Pa, refining temperature are under T=1500 ℃, the refining time condition that is 60min, carry out vacuum refinement; Be cooled to room temperature, can obtain product.
Embodiment products obtained therefrom analytical results is as follows:
Table 1 embodiment products obtained therefrom analytical results
Figure 2011100554723100002DEST_PATH_IMAGE011

Claims (8)

1. with product silica gel in phosphate fertilizer industry, produce a method for pure silicon, take product silica gel in phosphate fertilizer industry as silicon source, adopt carbothermic method to produce pure silicon, it is characterized in that, its step comprises:
A. raw materials pretreatment: product silica gel in phosphate fertilizer industry is washed, is dried, after pre-treatment, dioxide-containing silica reaches 95%, by charcoal, refinery coke fragmentation, screening, dry, selecting granularity is charcoal, the refinery coke of 100~50 μ m, and its fixed carbon content reaches respectively 70-75% and 80-85%;
B. prepare burden: selecting granularity is the product silica gel in phosphate fertilizer industry of 150~75 μ m, selecting granularity is charcoal, the refinery coke of 100~50 μ m, then with silica gel and charcoal, refinery coke, carry out the batching of product silica gel in phosphate fertilizer industry, charcoal, refinery coke, and mix, obtain mixture;
C. reaction: step b gained mixture is sent into pyrocarbon pipe furnace and preheat, the condition that preheats is for being evacuated to 5.0 * 10 -2below mbar, be warming up to 500~700 ℃, temperature rise rate is 25~50 ℃ of min -1, insulation 10~30min, protective atmosphere condition is for being evacuated to 5.0 * 10 -2below mbar, take argon gas as protection gas, protection air pressure is by force 0.02~0.04MPa, and shielding gas flow speed is 5.0~10.0CFH, and pressure is 25~75mbar, is warming up to 1775~1825 ℃, and temperature rise rate is 25~50 ℃ of min -1, insulation 20~30min;
D. cooling: adopt instrument to control cooling, reaction product can obtain silicon through cooling 6~8h to room temperature;
E. broken, silicon is crushed to suitable granularity 150~75 μ m;
F. wet purification: step e gained silicon is leached with leaching agent, purify;
G. after wet purification, wash with water to neutrality, dry;
H. vacuum refinement: under vacuum condition, refining, the purity of raising silicon;
I. cooling, product is cooled to room temperature, can obtain product.
2. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1, it is characterized in that: the product silica gel in phosphate fertilizer industry described in step a is that phosphate fertilizer by-product fluosilicic acid is produced the silica gel of separating out in hydrofluoric acid, anhydrous hydrogen fluoride process, and dioxide-containing silica is 85-95%.
3. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1, it is characterized in that: the pre-treatment of the product silica gel in phosphate fertilizer industry described in step a, i.e. wash conditions: liquid-solid ratio is 12: 1gml -1, washing time is 2h, stirring intensity is 300radmin -1, washing at least 3 times, its dioxide-containing silica reaches more than 95%; Drying conditions: 105 ± 5 ℃ of steady temperatures, dry 1~2h, dry number of times 1~2 time, to constant weight, its granularity is 150~75 μ m.
4. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1, it is characterized in that: the charcoal described in step a, the pre-treatment of refinery coke, i.e. broken, screening condition: by after charcoal, refinery coke fragmentation, with standard sieve screening, obtain charcoal, refinery coke that granularity is 100~50 μ m; Drying conditions: 105 ± 5 ℃ of steady temperatures, dry 1~2h, dry number of times 1~2 time, to constant weight.
5. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1, it is characterized in that: the fragmentation of the pure silicon described in step e, be about to after charcoal, refinery coke fragmentation, with standard sieve screening, obtain the pure silicon that granularity is 150~75 μ m.
6. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1, it is characterized in that: the wet purification described in step f, its processing condition: silicon particle size is D=150~75 μ m, wet purification progression is two-stage, leaching agent is followed successively by 8.00% HCl, 5.15% HF, liquid-solid ratio is 5: 1, and stir speed (S.S.) is 140 radmin -1magnetic agitation, extraction temperature is 71.3 ℃, extraction time is 4h.
7. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1, it is characterized in that: being dried described in step h, its drying conditions is: 105 ± 5 ℃ of steady temperatures, dry 1~2h, dry number of times 1~2 time, to constant weight.
8. according to the method for producing pure silicon with product silica gel in phosphate fertilizer industry described in right 1; it is characterized in that: the vacuum refinement described in step I; its processing condition: adopt argon gas to make protection gas, vacuum tightness is that P=0.5Pa, refining temperature are that T=1500 ℃, refining time are 60min.
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