CN116144922B - Preparation method of composite caking coal reduction pellets for industrial silicon - Google Patents
Preparation method of composite caking coal reduction pellets for industrial silicon Download PDFInfo
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- 239000003245 coal Substances 0.000 title claims abstract description 229
- 239000002131 composite material Substances 0.000 title claims abstract description 77
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 65
- 239000010703 silicon Substances 0.000 title claims abstract description 65
- 239000008188 pellet Substances 0.000 title claims abstract description 64
- 230000009467 reduction Effects 0.000 title claims abstract description 39
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000002245 particle Substances 0.000 claims abstract description 98
- 239000011230 binding agent Substances 0.000 claims abstract description 70
- 239000011247 coating layer Substances 0.000 claims abstract description 64
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000010410 layer Substances 0.000 claims abstract description 13
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 62
- 239000007767 bonding agent Substances 0.000 claims description 43
- 239000011248 coating agent Substances 0.000 claims description 16
- 238000000576 coating method Methods 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 229920000881 Modified starch Polymers 0.000 claims description 14
- 239000004368 Modified starch Substances 0.000 claims description 14
- 235000019426 modified starch Nutrition 0.000 claims description 14
- 235000019353 potassium silicate Nutrition 0.000 claims description 14
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical group [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 11
- 238000005253 cladding Methods 0.000 claims description 8
- 239000000853 adhesive Substances 0.000 claims 5
- 230000001070 adhesive effect Effects 0.000 claims 5
- 238000003723 Smelting Methods 0.000 abstract description 32
- 239000003638 chemical reducing agent Substances 0.000 abstract description 18
- 239000002994 raw material Substances 0.000 abstract description 6
- 230000009257 reactivity Effects 0.000 abstract description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 14
- 239000000377 silicon dioxide Substances 0.000 description 7
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 6
- 239000003610 charcoal Substances 0.000 description 5
- 239000002006 petroleum coke Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000000571 coke Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000002802 bituminous coal Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 239000011863 silicon-based powder Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/244—Binding; Briquetting ; Granulating with binders organic
- C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates
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- Manufacturing & Machinery (AREA)
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- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
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Abstract
The invention belongs to the technical field of efficient clean utilization of resources, and particularly relates to a preparation method of composite caking coal reduction pellets for industrial silicon. The reduction pellets are formed by wrapping coal serving as a carbonaceous material, water and a binder layer by layer to form pellets; and the coating layer is more than or equal to 1. The preparation method comprises the following steps: adding water into the bonding coal with different particle sizes and different bonding indexes according to the law that the small particles are wrapped with large particles and the high bonding index is wrapped with non-bonding index for layer-by-layer wrapping, then insulating air at 500-600 ℃ and roasting for 2-3 hours, and cooling to obtain the composite bonding coal reducer pellet. The invention takes coal as a carbonaceous raw material, utilizes the combination of different particle sizes and bonding properties to coat layer by layer to form a porous structure, and improves the pellet strength and the fixed carbon content by roasting the bonded coal. The invention not only can ensure that the product has high fixed carbon content, good reactivity, low ash content, proper bonding index and low cost, but also can produce high-quality industrial silicon, and can be completely used for smelting and producing the industrial silicon.
Description
Technical Field
The invention belongs to the technical field of efficient clean utilization of resources, and particularly relates to a preparation method of composite caking coal reduction pellets for industrial silicon.
Background
At present, most of carbonaceous reducing agents used in silicon industry smelting in China are traditional mixed carbonaceous reducing agents which are prepared from charcoal, petroleum coke, wood blocks and semi-coke serving as raw materials according to a certain proportion. With the expansion of industrial silicon products in domestic and foreign markets, the supply shortage and price rising of main raw carbonaceous reducing agent materials for silicon industry production are caused, wherein the goods sources of charcoal and petroleum coke are very tight, the price rising range is large, the quality is unstable, and the bonding index is lower, which definitely makes industrial silicon production face great difficulties. Thus, there is a great need in the market for a new reducing agent for use in the silicon industry.
The production and consumption of coal in China are dominant, wherein the coal has higher specific resistance and proper bonding index, is not easy to graphitize, and can replace charcoal to become a reducing agent for producing industrial silicon. The method has the advantages that the whole coal is only used as an industrial silicon smelting reducer, the reaction speed of furnace burden is increased under the conditions of high current and low voltage, the reaction is more complete, the silicon yield is improved, the energy consumption is reduced, the untreated coal has lower fixed carbon content, and the high volatile content can cause serious ignition of the furnace burden, so that the raw material waste is caused. At present, a carbonaceous reducing agent material obtained by mixing charcoal, petroleum coke and bituminous coal is adopted to reduce silica, for example, patent CN115072724A, the patent designs that biomass carbon, semi-coke, petroleum coke, coke reducing agent, bonded clean coal and unbonded clean coal are fully mixed according to mass ratio, and the mixture is fed into an ore smelting furnace by using a feeding device to carry out industrial silicon smelting production. Meanwhile, the patent CN113636560A also obtains a reducing agent by mixing 40 to 45 parts of charcoal powder, 20 to 25 parts of refined coal powder, 8 to 12 parts of petroleum coke powder, 3 to 6 parts of micro silicon powder, 4 to 5 parts of presoaked glue solution, 6 to 8 parts of composite binder and 4 to 5 parts of NaOH solution. However, the mixing technology may have the problems of low activity of the reducing agent, poor air permeability of the furnace burden, extra energy consumption and the like.
Disclosure of Invention
Aiming at the problems of the preparation of the bituminous coal reducing agent in the prior art, the invention provides a preparation method of the composite bonding coal reduction pellet for industrial silicon, which takes composite bonding coal as a carbonaceous raw material, and utilizes the combination of different particle sizes and bonding properties to coat layer by layer to form a porous structure for the first time, and the strength and the fixed carbon content of the pellet are improved by roasting the bonding coal, so that the pellet reaches a certain bonding index, the pellet is ensured to have high fixed carbon content, good reactivity, low ash content and proper bonding index, and can be used for producing high-quality industrial silicon, and the method can be completely used for smelting and producing industrial silicon.
A preparation method of composite caking coal reduction pellets for industrial silicon uses coal as carbonaceous material, and water and binder are mixed to form pellets layer by layer; and the coating layer is more than or equal to 1; namely, the composite caking coal reduction pellet for the industrial silicon comprises a first caking coal and a coating layer; wherein the first caking coal has a larger particle size than the coating coal; the caking index of the coal used for the first caking coal is less than the caking index of the coal used for the coating. The preparation method comprises the following steps: coating a first coating layer on the first bonding coal, and coating an ith coating layer on the ith-1 coating layer if the number of the coating layers is more than 2; and i is more than or equal to 2.
Preferably, the coating layer is 2 or more;
as a further preferred aspect, the first coating layer is directly coated on the first binder coal, and the second coating layer is coated on the first coating layer; and by analogy, the ith coating layer is coated on the ith-1 coating layer, and i is more than or equal to 2.
As a further preference, the particle size of the coal used for the i-1 th coating layer is larger than the particle size of the coal used for the i-th coating layer; the caking index of the coal used for the i-1 th coating layer is smaller than that of the coal used for the i-th coating layer.
Preferably, the particle size of the first binder coal is 5-16mm, further optimized to 6-15.5mm, and further preferably 6-15mm; the bond index is 0; the particle size of the coal (namely the second bonding coal) used by the first coating layer is 0.2-0.6mm, and the bonding index is 50-85; the particle size of the coal used for the second coating layer (the third bonding coal) is less than 0.1mm, and the bonding index is more than 85.
As a further preferable scheme, the particle size of the first caking coal is 14-15.5 mm, and is further optimized to 15mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.25-0.35 mm, and the particle size is further optimized to be 0.3mm, and the bonding index is 85; the particle size of the coal used for the second coating layer is less than 0.1mm, and the bonding index is 96; the mass ratio of the first bonding coal to the first coating layer to the second coating layer is as follows: 30:50:20.
As a further preferable scheme, the particle size of the first caking coal is 14-15.5 mm, and is further optimized to 15mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.25-0.35 mm, and the particle size is further optimized to be 0.35mm, and the bonding index is 85; the particle size of the coal used for the second coating layer is less than 0.1mm, and the bonding index is 94; the mass ratio of the first bonding coal to the first coating layer to the second coating layer is as follows: 20:40:40.
As a further preferable scheme, the particle size of the first caking coal is 8-10 mm, and is further optimized to be 8mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.4-0.5mm, preferably 0.45mm, and the caking index is 78; the particle size of the coal used for the second coating layer is less than 0.1mm, and the bonding index is 96; the mass ratio of the first bonding coal to the first coating layer to the second coating layer is as follows: 25:30:45.
Further, the composite caking coal reduction pellet for industrial silicon is prepared by the following steps when i=2:
Step 1, firstly, crushing three kinds of coals with different caking indexes into particles with required granularity according to the order from small caking indexes to large caking indexes; wherein the particle size of the first kind of caking coal is 6-10mm, the caking index is 0, the particle size of the second kind of caking coal is 0.3-0.5mm, the caking index is 65-85, the particle size of the third kind of caking coal is less than 0.1mm, and the caking index is more than 85;
Step 2, adding the first bonding coal into the second bonding coal, adding 8-12 wt.% of water, and stirring 0.8-1.2wt.%, preferably 1 wt.% of binder until the binder is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 20-30 mm;
step 3, adding the agglomerate particles in the step 2 into the third caking coal, adding 8-12 wt.% of water, and stirring 0.8-1.2wt.%, preferably 1 wt.% of binder until obvious caking, and coating the agglomerate particles in the step 2 into agglomerate particles with the diameter of 30-60 mm;
And 4, placing the agglomerate particles formed in the step 3 into an air-isolated low-temperature roasting furnace at 500-600 ℃ for 2-3 hours, and cooling the mixture to room temperature along with a furnace to obtain the composite caking coal reduction pellets.
In the step 1, the mass ratio of the first bonding coal to the second bonding coal to the third bonding coal is 20-30:30-50:20-50.
The low-temperature roasting temperature in the step 4 is 500-600 ℃ and the time is 2-3 h.
The coal fixed carbon content of the three different caking indexes in the step 1 is 55 to 65 wt%.
The binder in the steps 2 and 3 is an organic-inorganic composite binder, wherein the inorganic binder accounts for 20-40 wt% and the organic binder accounts for 60-80 wt%. The inorganic binder is selected from water glass; the organic binder is selected from the group consisting of textured starches.
The bonding index of the composite bonding coal reduction pellet for the industrial silicon prepared by the method is 60-80, and the cold strength is 8-12 MPa.
The beneficial effects of the invention are as follows:
1. The invention takes the composite caking coal as the carbonaceous raw material, and utilizes the combination of different particle diameters and caking property of the three caking coals to coat layer by layer to form a porous structure, and the smaller the particle diameter is, the higher the caking effect is, so that a large number of gaps exist in the particles, the full dispersion in use is facilitated, the full combustion of the carbonaceous material is ensured, and the combustion stability is also improved.
2. The invention improves the strength of the pellets by roasting the bonded coal, the colloid produced by the coal at a certain temperature enables the pellets to be combined more tightly, improves the strength of the reduced pellets of the composite bonded coal, and simultaneously the temperature is increased to enable the reduced pellets of the composite bonded coal to reach a certain bonding index, thereby not only ensuring the high content of fixed carbon, good reaction activity, low ash content, proper bonding index and low cost, but also being capable of producing high-quality industrial silicon and being completely used for smelting and producing the industrial silicon.
3. The composite caking coal reduction pellets for industrial silicon prepared by the invention are released in a large amount of volatile matters after being roasted, the fixed carbon content is more than 75 wt%, the volatile matter content is 15 wt% to 20 wt%, the ash content is less than 4 wt%, the cold strength is 8 to 12MPa, and the caking index is 60 to 80, so that the composite caking coal reduction pellets for industrial silicon can be completely suitable for industrial silicon.
4. The modified starch binder used for the composite bonding coal reduction pellet for industrial silicon prepared by the invention is released as volatile matters in the industrial silicon smelting process, so that the pellet forms a porous structure and the chemical reaction activity is increased.
Detailed Description
The invention will be described in further detail with reference to specific embodiments, but the scope of the invention is not limited to the description.
Example 1
The industrial silicon is reduced into pellets by using the composite caking coal, the fixed carbon content reaches 77.4wt.%, the volatile content reaches 19wt.%, the ash content reaches 3.6wt.%, the caking index G reaches 70, and the pellet cold strength reaches 10MPa.
The preparation method of the composite caking coal reduction pellet for the industrial silicon comprises the following steps:
Step 1, firstly, crushing three kinds of coals with different caking indexes into 10mm,0.5mm and 0.075mm particle sizes respectively according to the order of the caking indexes from small to large, wherein the caking index of the first kind of caking coal is 0, and the caking index of the second kind of caking coal is 75; the third caking coal has a caking index of 90, and the mass ratio of the first caking coal to the second caking coal to the third caking coal is 20:50:30wt.%;
Step 2, adding the first bonding coal, 9wt.% of water and 1wt.% of bonding agent into the second bonding coal, stirring until the bonding coal is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 25mm, wherein the bonding agent is an organic-inorganic composite bonding agent, the inorganic bonding agent accounts for 30wt%, the organic bonding agent accounts for 70wt%, the inorganic bonding agent is water glass, and the organic bonding agent is modified starch;
Step 3, adding the agglomerate particles in the step 2, 9wt.% of water and 1wt.% of binder into the third type of caking coal, stirring until the agglomerate particles are obviously agglomerated, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 45mm, wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 30 wt.% in the organic-inorganic composite binder, the organic binder accounts for 70 wt.%, the inorganic binder is water glass, and the organic binder is modified starch;
and 4, placing the agglomerate particles formed in the step 3 into an air-insulated low-temperature roasting furnace at the temperature of 500 ℃ for 2 hours, and cooling the mixture to room temperature along with a furnace to obtain the composite caking coal reduction pellets.
The raw materials used are as follows:
The first caking coal had a fixed carbon content of 60wt.%, a volatile content of 32.6wt.%, and an ash content of 1wt.%;
The second caking coal had a fixed carbon content of 59wt.%, a volatile content of 36.7wt.%, and an ash content of 1.2wt.%;
the third caking coal had a fixed carbon content of 55wt.%, a volatile content of 38.2wt.%, and an ash content of 0.4wt.%.
200Kg of silica (99.5% SiO 2、0.05％Al2O3、0.03％Fe2O3 and 0.05% CaO) is crushed into blocks with the granularity of 20-100 mm, and the blocks are cleaned and sieved, are uniformly mixed with 103kg of the composite carbonaceous reducing agent, are added into a submerged arc furnace for smelting (the smelting temperature is 2200 ℃), the smelting is stable under the furnace condition, and 85.4kg of industrial silicon products are obtained after smelting, the components of the industrial silicon products are Si >99.5 wt%, fe is less than or equal to 0.19 wt%, al is less than or equal to 0.09 wt%, and Ca is less than or equal to 0.05 wt%.
Example 2
The composite caking coal for industrial silicon reduces the pellets, the fixed carbon content reaches 79.6wt.%, the volatile content reaches 17wt.%, the ash content reaches 3.4wt.%, the caking index G reaches 80, and the pellet cold strength reaches 12MPa.
The preparation method of the composite caking coal reduction pellet for the industrial silicon comprises the following steps:
Step 1, firstly, crushing three kinds of coals with different caking indexes into 15mm,0.3mm and 0.068mm particle sizes respectively according to the order from small caking indexes to large caking indexes, wherein the caking index of the first kind of caking coal is 0, and the caking index of the second kind of caking coal is 85; the third caking coal has a caking index of 96, and the mass ratio of the first caking coal to the second caking coal to the third caking coal is 30:50:20wt.%;
Step 2, adding a first bonding coal, 12wt.% of water and 1wt.% of bonding agent into a second bonding coal, stirring until the bonding coal is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 20mm, wherein the bonding agent is an organic-inorganic composite bonding agent, the inorganic bonding agent accounts for 20wt%, the organic bonding agent accounts for 80wt%, the inorganic bonding agent is water glass, and the organic bonding agent is modified starch;
Step 3, adding the agglomerate particles in the step 2, 12wt.% of water and 1wt.% of binder into the third type of caking coal, stirring until the agglomerate particles are obviously agglomerated, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 50mm, wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 20 wt.% in the organic-inorganic composite binder, the organic binder accounts for 80 wt.% in the organic-inorganic composite binder, the inorganic binder is water glass, and the organic binder is modified starch;
And 4, placing the agglomerate particles formed in the step 3 into an air-insulated low-temperature roasting furnace at 550 ℃ for 2 hours, and cooling the mixture to room temperature along with a furnace to obtain the composite bonded coal reduction pellets.
The first caking coal had a fixed carbon content of 63wt.%, a volatile content of 33.6wt.%, and an ash content of 0.6wt.%;
the second binder coal had a fixed carbon content of 58wt.%, a volatile content of 34.5wt.%, and an ash content of 1.2wt.%;
the third caking coal had a fixed carbon content of 56wt.%, a volatile content of 36.2wt.%, and an ash content of 1.6wt.%.
200Kg of silica (99.5% SiO 2、0.05％Al2O3、0.03％Fe2O3 and 0.05% CaO) is crushed into blocks with the granularity of 20-100 mm, and the blocks are cleaned and sieved, then the blocks are uniformly mixed with 100kg of the composite carbonaceous reducing agent, the mixture is added into a submerged arc furnace for smelting (the smelting temperature is 2200 ℃), the smelting is stable under the furnace condition, 91.3kg of industrial silicon products are obtained after smelting, 12290Kw h, the components of the industrial silicon products are Si >99.6 wt%, fe is less than or equal to 0.19 wt%, al is less than or equal to 0.09 wt%, and Ca is less than or equal to 0.05 wt%.
Example 3
The industrial silicon is reduced into pellets by using the composite caking coal, the fixed carbon content reaches 81.5wt.%, the volatile content reaches 15wt.%, the ash content reaches 3.5wt.%, the caking index G reaches 60, and the pellet cold strength reaches 9MPa.
The preparation method of the composite caking coal reduction pellet for the industrial silicon comprises the following steps:
Step 1, firstly, crushing three kinds of coals with different caking indexes into particles with the granularity of 5mm,0.4mm and 0.068mm respectively according to the order of the caking indexes from small to large, wherein the caking index of the first kind of caking coal is 0, and the caking index of the second kind of caking coal is 65; the third caking coal has a caking index of 91, and the mass ratio of the first caking coal to the second caking coal to the third caking coal is 30:50:20wt.%;
Step 2, adding a first bonding coal, 12wt.% of water and 1wt.% of bonding agent into a second bonding coal, stirring until the bonding coal is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 24mm, wherein the bonding agent is an organic-inorganic composite bonding agent, the inorganic bonding agent accounts for 25wt%, the organic bonding agent accounts for 75wt%, the inorganic bonding agent is water glass, and the organic bonding agent is modified starch;
Step 3, adding the agglomerate particles in the step 2, 12wt.% of water and 1wt.% of binder into the third type of caking coal, stirring until the agglomerate particles are obviously agglomerated, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 35mm, wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 25wt%, the organic binder accounts for 75wt%, the inorganic binder is water glass and the organic binder is modified starch;
And 4, placing the agglomerate particles formed in the step 3 into a furnace to cool to room temperature along with the low-temperature roasting for 3 hours at 600 ℃ under the condition of isolating air, so as to obtain the composite caking coal reduction pellets.
The first caking coal had a fixed carbon content of 59wt.%, a volatile content of 31.6wt.%, and an ash content of 0.7wt.%;
the second binder coal had a fixed carbon content of 65wt.%, a volatile content of 33.5wt.%, and an ash content of 1.2wt.%;
the third caking coal had a fixed carbon content of 56wt.%, a volatile content of 37.2wt.%, and an ash content of 1.6wt.%.
200Kg of silica (99.5% SiO 2、0.05％Al2O3、0.03％Fe2O3 and 0.05% CaO) is crushed into blocks with the granularity of 20-100 mm, and the blocks are cleaned and sieved, then the blocks are uniformly mixed with 98kg of the composite carbonaceous reducing agent, the mixture is added into a submerged arc furnace for smelting (the smelting temperature is 2200 ℃), the smelting is basically stable, 79.3kg of industrial silicon products are obtained after smelting, 12990Kw.h, the components of the industrial silicon products are Si >99.4 wt%, fe is less than or equal to 0.19 wt%, al is less than or equal to 0.09 wt%, and Ca is less than or equal to 0.05 wt%.
Example 4
The industrial silicon is reduced into pellets by using the composite caking coal, the fixed carbon content reaches 78 wt%, the volatile content reaches 19 wt%, the ash content reaches 3 wt%, the caking index G reaches 75, and the pellet cold strength reaches 11MPa.
The preparation method of the composite caking coal reduction pellet for the industrial silicon comprises the following steps:
Step 1, firstly, crushing three kinds of coals with different caking indexes into 15mm,0.35mm and 0.065mm particle sizes respectively according to the order from small caking indexes to large caking indexes, wherein the caking index of the first kind of caking coal is 0, and the caking index of the second kind of caking coal is 85; the third caking coal has a caking index of 94, and the mass ratio of the first caking coal to the second caking coal to the third caking coal is 20:40:40wt.%;
Step 2, adding the first bonding coal, 10wt.% of water and 1wt.% of bonding agent into the second bonding coal, stirring until the bonding coal is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 30mm, wherein the bonding agent is an organic-inorganic composite bonding agent, the inorganic bonding agent accounts for 40wt%, the organic bonding agent accounts for 60wt%, the inorganic bonding agent is water glass, and the organic bonding agent is modified starch;
Step 3, adding the agglomerate particles in the step 2, 10wt.% of water and 1wt.% of binder into the third type of caking coal, stirring until the agglomerate particles are obviously agglomerated, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 55mm, wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 40wt%, the organic binder accounts for 60wt%, the inorganic binder is water glass and the organic binder is modified starch;
And 4, placing the agglomerate particles formed in the step 3 into an air-isolated low-temperature roasting furnace at 550 ℃ for 3 hours, and cooling the mixture to room temperature along with a furnace to obtain the composite bonded coal reduction pellets.
The first caking coal had a fixed carbon content of 55wt.%, a volatile content of 34.6wt.%, and an ash content of 0.5wt.%;
the second caking coal had a fixed carbon content of 60wt.%, a volatile content of 36.5wt.%, and an ash content of 1.4wt.%;
The third caking coal had a fixed carbon content of 61wt.%, a volatile content of 33.2wt.%, and an ash content of 0.6wt.%.
200Kg of silica (99.5% SiO 2、0.05％Al2O3、0.03％Fe2O3 and 0.05% CaO) is crushed into blocks with the granularity of 20-100 mm, and the blocks are cleaned and sieved, are uniformly mixed with 102kg of the composite carbonaceous reducing agent, are added into a submerged arc furnace for smelting (the smelting temperature is 2200 ℃), the smelting is stable under the furnace condition, 87.3kg of industrial silicon products are obtained after smelting, 11890Kw h, the components of the industrial silicon products are Si >99.6 wt%, fe is less than or equal to 0.19 wt%, al is less than or equal to 0.09 wt%, and Ca is less than or equal to 0.05 wt%.
Example 5
The industrial silicon is reduced into pellets by using the composite caking coal, the fixed carbon content reaches 80.8wt.%, the volatile content reaches 18wt.%, the ash content reaches 1.2wt.%, the caking index G reaches 65, and the pellet cold strength reaches 8MPa.
The preparation method of the composite caking coal reduction pellet for the industrial silicon comprises the following steps:
Step 1, firstly, crushing three kinds of coals with different caking indexes into 18mm,0.4mm and 0.065mm particle sizes respectively according to the order from small to large, wherein the caking index of the first kind of caking coal is 0, and the caking index of the second kind of caking coal is 80; the third caking coal has a caking index of 89, and the mass ratio of the first caking coal to the second caking coal to the third caking coal is 30:30:40wt.%;
Step 2, adding the first bonding coal, 11wt.% of water and 1wt.% of bonding agent into the second bonding coal, stirring until the bonding coal is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 22mm, wherein the bonding agent is an organic-inorganic composite bonding agent, the inorganic bonding agent accounts for 20wt%, the organic bonding agent accounts for 80wt%, the inorganic bonding agent is water glass, and the organic bonding agent is modified starch;
Step 3, adding the agglomerate particles in the step 2, 11wt.% of water and 1wt.% of binder into the third type of caking coal, stirring until the agglomerate particles are obviously agglomerated, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 58mm, wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 20 wt.% in the organic-inorganic composite binder, the organic binder accounts for 80 wt.% in the organic-inorganic composite binder, the inorganic binder is water glass, and the organic binder is modified starch;
And 4, placing the agglomerate particles formed in the step 3 into a furnace to cool to room temperature along with the low-temperature roasting for 2 hours at 600 ℃ under the condition of isolating air, so as to obtain the composite caking coal reduction pellets.
The first caking coal had a fixed carbon content of 58wt.%, a volatile content of 36.2wt.%, and an ash content of 0.6wt.%;
the second binder coal had a fixed carbon content of 60wt.%, a volatile content of 36.5wt.%, and an ash content of 0.3wt.%;
The third caking coal had a fixed carbon content of 65wt.%, a volatile content of 33.3wt.%, and an ash content of 0.2wt.%.
200Kg of silica (99.5% SiO 2、0.05％Al2O3、0.03％Fe2O3 and 0.05% CaO) is crushed into blocks with the granularity of 20-100 mm, and the blocks are cleaned and sieved, then the blocks are uniformly mixed with 99kg of the composite carbonaceous reducing agent, the mixture is added into a submerged arc furnace for smelting (the smelting temperature is 2200 ℃), the smelting is stable under the furnace condition, 80.3kg of industrial silicon products are obtained after smelting, the consumption of electric energy is 12590Kw.h, the components of the industrial silicon products are Si >99.5 wt%, fe is less than or equal to 0.19 wt%, al is less than or equal to 0.09 wt%, and Ca is less than or equal to 0.05 wt%.
Example 6
The composite caking coal for industrial silicon reduces the pellets, the fixed carbon content reaches 78.9wt.%, the volatile content reaches 17.4wt.%, the ash content reaches 3.7wt.%, the caking index G reaches 77, and the pellet cold strength reaches 11MPa.
The preparation method of the composite caking coal reduction pellet for the industrial silicon comprises the following steps:
Step 1, firstly, crushing three kinds of coals with different caking indexes into particles with the particle sizes of 8mm,0.45mm and 0.075mm respectively according to the order of the caking indexes from small to large, wherein the caking index of the first kind of caking coal is 0, and the caking index of the second kind of caking coal is 78; the third caking coal has a caking index of 96, and the mass ratio of the first caking coal, the second caking coal and the third caking coal is 25:30:45wt.%;
Step 2, adding the first bonding coal, 10wt.% of water and 1wt.% of bonding agent into the second bonding coal, stirring until the bonding coal is obviously agglomerated, and cladding the first bonding coal into agglomerate particles with the diameter of 22mm, wherein the bonding agent is an organic-inorganic composite bonding agent, the inorganic bonding agent accounts for 30wt%, the organic bonding agent accounts for 70wt%, the inorganic bonding agent is water glass, and the organic bonding agent is modified starch;
Step 3, adding the agglomerate particles in the step 2, 10wt.% of water and 1wt.% of binder into the third type of caking coal, stirring until the agglomerate particles are obviously agglomerated, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 60mm, wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 30 wt.% in the organic-inorganic composite binder, the organic binder accounts for 70 wt.%, the inorganic binder is water glass, and the organic binder is modified starch;
And 4, placing the agglomerate particles formed in the step 3 into an air-isolated low-temperature roasting furnace at 500 ℃ for 3 hours, and cooling the mixture to room temperature along with a furnace to obtain the composite bonded coal reduction pellets.
The first caking coal had a fixed carbon content of 64wt.%, a volatile content of 31.2wt.%, and an ash content of 0.9wt.%;
The second caking coal had a fixed carbon content of 57wt.%, a volatile content of 34.5wt.%, and an ash content of 1.2wt.%;
the third caking coal had a fixed carbon content of 59wt.%, a volatile content of 35.3wt.%, and an ash content of 1.6wt.%.
200Kg of silica (99.5% SiO 2、0.05％Al2O3、0.03％Fe2O3 and 0.05% CaO) is crushed into blocks with the granularity of 20-100 mm, and the blocks are cleaned and sieved, then the blocks are uniformly mixed with 101kg of the composite carbonaceous reducing agent, the mixture is added into a submerged arc furnace for smelting (the smelting temperature is 2200 ℃), the smelting is stable under the furnace condition, 91.1kg of industrial silicon products are obtained after smelting, the consumption of electric energy 11990Kw.h, the components of the industrial silicon products are Si >99.6 wt%, fe is less than or equal to 0.19 wt%, al is less than or equal to 0.09 wt%, and Ca is less than or equal to 0.05 wt%.
While the present invention has been described in detail with reference to the specific embodiments thereof, the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present invention.
Claims (10)
1. A preparation method of composite caking coal reduction pellets for industrial silicon is characterized by comprising the following steps: coal is taken as a carbonaceous material, water and a binder are matched to be coated layer by layer to form a pellet; and the coating layer is more than or equal to 1;
The composite caking coal reduction pellet for the industrial silicon comprises a first caking coal and a coating layer; wherein the first caking coal has a larger particle size than the coating coal; the caking index of the coal used for the first caking coal is smaller than the caking index of the coal used for the coating layer; a first coating layer in the coating layers is coated on the first bonding coal; the preparation method comprises the following steps: coating a first coating layer on the first bonding coal, and coating an ith coating layer on the ith-1 coating layer if the number of the coating layers is more than 2; and i is more than or equal to 2.
2. The method for preparing the composite caking coal reduction pellets for industrial silicon according to claim 1, which is characterized by comprising the following steps: the coating layer is more than or equal to 2.
3. The method for preparing the composite caking coal reduction pellets for industrial silicon according to claim 2, which is characterized by comprising the following steps: the first coating layer is directly coated on the first bonding coal, and the second coating layer is coated on the first coating layer; and by analogy, coating the ith coating layer on the ith-1 coating layer, wherein i is more than or equal to 2;
Wherein the particle size of the coal used for the i-1 th coating layer is larger than that of the coal used for the i-th coating layer; the caking index of the coal used for the i-1 th coating layer is smaller than that of the coal used for the i-th coating layer.
4. The method for preparing the composite caking coal reduction pellets for industrial silicon according to claim 3, wherein the method comprises the following steps: the particle size of the first kind of caking coal is 5-16mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.2-0.6mm, and the caking index is 50-85; the particle size of the coal used for the second coating layer is less than 0.1mm, and the caking index is more than 85.
5. The method for preparing the composite caking coal reduction pellets for industrial silicon according to claim 3, wherein the method comprises the following steps: when i=2, the composite caking coal reduction pellet for industrial silicon is prepared by the following steps:
step 1, firstly, crushing three kinds of coals with different caking indexes into particles with required granularity according to the order from small caking indexes to large caking indexes; wherein the first kind of caking coal has a grain size of 5-15.5mm, a caking index of 0, the second kind of caking coal has a grain size of 0.3-0.5mm, a caking index of 50-85, and the third kind of caking coal has a grain size of <0.1 mm, and a caking index of > 85;
Step 2, adding the first bonding coal into the second bonding coal, adding 8-12 wt wt.% of water, stirring 0.8-1.2wt.% of bonding agent until obvious caking, and cladding the first bonding coal into agglomerate particles with the diameter of 20-30 mm;
Step3, adding the agglomerate particles in the step 2 into the third caking coal, adding 8-12 wt wt.% of water, stirring 0.8-1.2wt.% of binder until obvious caking, and coating and forming the agglomerate particles in the step 2 into agglomerate particles with the diameter of 30-60 mm;
And 4, placing the agglomerate particles formed in the step 3 into an air-isolated low-temperature roasting furnace at 500-600 ℃ for 2-3 hours, and cooling the mixture to room temperature along with a furnace to obtain the composite caking coal reduction pellets.
6. The method for preparing the composite caking coal reduction pellet for industrial silicon according to claim 5, which is characterized in that:
the particle size of the first caking coal is 6-15mm, and the caking index is 0;
In the step 1, the mass ratio of the first bonding coal to the second bonding coal to the third bonding coal is 20-30:30-50:20-50.
7. The method for preparing the composite caking coal reduction pellet for industrial silicon according to claim 5, which is characterized in that:
The particle size of the first kind of caking coal is 14-15.5 mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.25-0.35 mm, and the bonding index is 85; the particle size of the coal used for the second coating layer is less than 0.1mm, and the bonding index is 96; the mass ratio of the first bonding coal to the first coating layer to the second coating layer is as follows: 30:50:20.
8. The method for preparing the composite caking coal reduction pellet for industrial silicon according to claim 5, which is characterized in that:
The particle size of the first kind of caking coal is 14-15.5 mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.25-0.35 mm, and the bonding index is 85; the particle size of the coal used for the second coating layer is less than 0.1mm, and the bonding index is 94; the mass ratio of the first bonding coal to the first coating layer to the second coating layer is as follows: 20:40:40.
9. The method for preparing the composite caking coal reduction pellet for industrial silicon according to claim 5, which is characterized in that:
the particle size of the first kind of caking coal is 8-10 mm; the bond index is 0; the particle size of the coal used for the first coating layer is 0.4-0.5mm, and the caking index is 78; the particle size of the coal used for the second coating layer is less than 0.1mm, and the bonding index is 96; the mass ratio of the first bonding coal to the first coating layer to the second coating layer is as follows: 25:30:45.
10. The method for preparing the composite caking coal reduction pellet for industrial silicon according to claim 5, which is characterized in that:
The fixed carbon content of the coal with three different caking indexes in the step 1 is 55 to 65wt.%;
The adhesive in the step 2 and the step 3 is an organic-inorganic composite adhesive, wherein the inorganic adhesive accounts for 20-40 wt% of the composite adhesive, and the organic adhesive accounts for 60-80 wt%; the inorganic binder is water glass; the organic binder is modified starch.
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