CN116282033A - A kind of preparation method of honeycomb reducing pellets for industrial silicon - Google Patents

Abstract

The invention relates to a preparation method of honeycomb reduction pellets for industrial silicon, and belongs to the technical field of efficient clean utilization of resources. The honeycomb reduction pellet for the industrial silicon is prepared by taking coking coal with different particle sizes as a carbonaceous material, mixing and stirring the coking coal with water and a binder, coating the coking coal into a honeycomb shape layer by layer, then roasting the honeycomb reduction pellet for the industrial silicon at the low temperature of 400-600 ℃ for 2-4 hours while isolating air, and cooling the honeycomb reduction pellet for the industrial silicon. According to the invention, coking coal is used as a carbonaceous material, and the porous honeycomb structure is formed by layer-by-layer cladding after mixing and stirring by utilizing the combination of different particle sizes and binding properties, and the density, the porosity and the fixed carbon content of the pellets are improved by roasting the coking coal. The honeycomb reduction pellet for industrial silicon has high fixed carbon content, good reactivity, low ash content, high specific resistance and low cost; the honeycomb reduction pellet for industrial silicon is applied to industrial silicon smelting, the carbon burning loss rate is reduced by 8% -12%, and the silicon yield is improved by 4% -8%.

Description

A kind of preparation method of honeycomb reducing pellets for industrial silicon

technical field

The invention relates to a method for preparing honeycomb-shaped reduced pellets for industrial silicon, and belongs to the technical field of efficient and clean utilization of resources.

Background technique

my country's silicon industry smelting mainly mixes two or more raw materials such as coal, petroleum coke, semi-coke, blue charcoal, charcoal, wood blocks (bagasse, peanut shells, etc.) in a certain proportion as carbonaceous raw materials. According to the use of carbonaceous reducing agent, the production of industrial silicon can be divided into all-coal process, half-coal and half-coke process, etc. The all-coal process uses clean coal as a carbonaceous reducing agent, and the semi-coal and semi-coke uses charcoal, bituminous coal, petroleum coke, etc. as reducing agents. Although charcoal has good reducibility, it is not environmentally friendly. Although petroleum coke can be used as a carbonaceous reducing agent, because of its high degree of graphitization with the increase of calcination temperature, its electrical conductivity increases, and its specific resistance drops sharply; Serious encrustation will affect the gas permeability of the furnace charge, cause severe fire sting, and make the furnace condition difficult to control. Therefore, the future development direction is mainly coal. However, the ash content of coal is high, and pyrolysis at high temperature affects the gas permeability of the furnace charge, reduces the utilization rate of carbon raw materials, and also causes ash and coking in the heated area of the furnace, increasing slag, and easily causing problems such as rising of the furnace bottom. Therefore, the research and development of new reducing agents for industrial silicon smelting is the only way for the development of silicon industry.

Contents of the invention

The present invention aims at the problem of reducing agent preparation in industrial silicon smelting in the prior art, and provides a preparation method of honeycomb-shaped reducing pellets for industrial silicon, using coking coal as carbonaceous material, and using different particle sizes and bonding properties for the first time After combined mixing and stirring, the porous honeycomb structure is formed layer by layer, and the density, porosity and fixed carbon content of the pellets are increased by roasting coking coal, so that the pellets can reach a certain cohesion index. The honeycomb reducing pellets for industrial silicon have a reactivity of over 99% at 1000°C, a fixed carbon content of over 75%, a volatile matter content of 12-20%, ash content of less than 4%, and a specific resistance of 3000-4000Ω. m.

A method for preparing honeycomb-shaped reducing pellets for industrial silicon of the present invention comprises the following steps:

Step 1 Preparation of central honeycomb pellets

The raw materials used in the central honeycomb pellets include low-caking coal and medium-caking coal. The particle size of low-caking coal is 5-15mm, and the caking index is less than or equal to 20. The particle size of medium-caking coal used is 0.2-0.6mm. for 50-65;

When preparing central honeycomb pellets, the mass ratio of low-caking coal and medium-caking coal used is 40-50:30-40;

Add low-viscosity coal to medium-sticky coal, mix and stir evenly, then add 8wt.% to 12wt.% of water, 0.8-1.2wt.%, preferably 1wt% of binder, stir until obvious agglomeration, and shape into a diameter of 20 -30mm central honeycomb pellets;

Step 2 Coating

Select high-caking coals with different particle sizes and cohesive indices, and coat the central honeycomb pellets layer by layer; sequentially coat the first coating layer on the central honeycomb pellets, and coat the first coating layer on the first coating layer. 2 coating layers, and so on, coating the i+1th coating layer on the i-th coating layer; obtaining formed agglomerate particles;

Where i is a positive integer greater than or equal to 1; the caking index of the high-caking coal used in the i-th cladding layer is less than the caking index of the high-caking coal used in the i+1 cladding layer; the caking index of the high-caking coal used in the i-th cladding layer The diameter is greater than the sticky diameter of the high caking coal used in the i+1 cladding layer; and the diameter of the high caking coal used in the i cladding layer is smaller than the diameter of the medium caking coal used in the central honeycomb pellet;

Among them, the mass ratio of the low-viscosity coal used in the central honeycomb pellets and the high-viscosity coal used in the first cladding layer of the central honeycomb pellets is 40-50:30-40:20-30;

The mass ratio of the high sticky coal used in the first cladding layer to the high sticky coal used in the second cladding layer is 20-30:20-30;

The particle size of the high caking coal used in the first cladding layer is 0.05-0.1mm, and the caking index is 70-85;

Step 3: put the agglomerate particles shaped in step 2 at a temperature of 400-600° C. for 2-4 hours in the absence of air and low-temperature roasting, and cool down to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

The coal used in the present invention is preferably coking coal. Of course other carbonaceous materials can also be used in the present invention.

As a preference, the present invention can also introduce low-cohesive coal when preparing any cladding layer; the particle size and cohesion index of the introduced low-cohesive coal and the low-cohesive coal used to prepare the central honeycomb pellets are basically the same. That is, when preparing any cladding layer, low-caking coal can also be introduced; the particle size of the low-caking coal is 5-15mm, and the caking index is less than or equal to 20.

As a preference, when preparing any cladding layer in the present invention, the mass ratio of the introduced low-sticky coal to the high-sticky coal used in the layer is 20-50:50-80. The reason why the present invention is to control the mass ratio of the introduced low-viscosity coal to the high-viscosity coal used in the layer to be 20-50:50-80 when preparing any cladding layer is because it is necessary to control the density of the prepared honeycomb-shaped reduced pellets. The cohesion index is in the range of 60-80, and the cold strength is in the range of 8-14MPa; if the proportion of low-caking coal introduced is too high, the pellets will be easy to crack and powder will fall off, resulting in waste of raw materials; if it is too low, it will lead to power consumption Consumption increases, energy loss increases, and costs increase.

As a further preference, when preparing the first cladding layer in the present invention, the mass ratio of the introduced low-sticky coal to the high-sticky coal used in this layer is 20-50:50-80. Preferably it is 30-50:50-70.

As a further preference, when preparing the second cladding layer in the present invention, the mass ratio of the introduced low-sticky coal to the high-sticky coal used in this layer is 20-50:50-80. Preferably it is 20-40:60-80.

As one of the further preferred schemes, the particle size of the low-caking coal used in the central honeycomb pellets is 7mm, the caking index is 5, the particle size of the medium-caking coal used is 0.3mm, and the caking index is 55; the first coating The particle size of high caking coal used in the first layer is 0.06mm, and the caking index is 75; the particle diameter of high caking coal used in the second cladding layer is 0.025mm, and the caking index is 90.

The mass ratio of the low-viscosity coal used in the central honeycomb pellet, the medium-caused coal used in the central honeycomb pellet, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 45:30:30:25.

As one of the further preferred schemes, the particle size of the low-caking coal used in the core honeycomb pellets is 8mm, the caking index is 15, the particle size of the medium-caking coal used is 0.3mm, and the caking index is 60; the first coating The particle size of high caking coal used in the first layer is 0.065mm, and the caking index is 70; the particle diameter of high caking coal used in the second cladding layer is 0.044mm, and the caking index is 94.

The mass ratio of the low-viscosity coal used in the central honeycomb pellets, the medium-caused coal used in the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 40:35:25:25.

As one of the further preferred schemes, the particle size of the low-caking coal used in the central honeycomb pellets is 10mm, the caking index is 10, the particle size of the medium caking coal used is 0.4mm, and the caking index is 64; the first coating The particle size of high caking coal used in the first layer is 0.075mm, and the caking index is 80; the particle diameter of high caking coal used in the second cladding layer is 0.037mm, and the caking index is 96.

The mass ratio of the low-viscosity coal used in the central honeycomb pellets, the medium-caused coal used in the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 50:35:30:25.

Further, the honeycomb-shaped reduced pellets for industrial silicon, when i=2, are prepared through the following steps, including the following steps:

Step 1, first crush four kinds of coal with different caking index to the required particle size; among them, the particle size of low caking coal is 6-12mm, and the caking index is 5-20; the particle size of medium caking coal is 0.3 -0.5mm, the caking index is 55-65; the particle size of high caking coal used in the first cladding layer is 0.06-0.1mm, and the caking index is 70-85; the particle diameter of high caking coal used in the second cladding layer It is 0.02-0.045mm, and the bonding index is >85.

Step 2: Add low-viscosity coal to medium-caking coal, mix and stir evenly at a mass ratio of 40-50:30-40, then add 8wt.% to 12wt.% of water, 0.8-1.2wt.%, preferably 1wt% Stir the binder until it agglomerates obviously, forming a central honeycomb pellet with a diameter of 20-30mm;

Step 3: After mixing the low-viscosity coal and the high-viscosity coal used in the first cladding layer according to the mass ratio of 30-50:50-70 and stirring evenly, add the central honeycomb pellet in step 2, and then add 8wt.%~12wt. % of water, 0.8-1.2wt.%, preferably 1wt% of binder, stirred until obvious agglomeration, and the central honeycomb pellet in step 2 is overmolded into agglomerate particles with a diameter of 30-50mm;

Step 4: Mix the low-viscosity coal and the high-viscosity coal used in the second cladding layer according to the mass ratio of 20-40:60-80, and then add the agglomerate particles in step 3, and then add 8wt.%~12wt.% % of water, 0.8-1.2wt.%, preferably 1wt% of binder, stirred until obvious agglomeration, and the central honeycomb pellets in step 3 were overmolded into agglomerate particles with a diameter of 50-60mm;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 400-600° C. for 2-4 hours in isolation from air and low-temperature roasting, and cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

The fixed carbon content of the coals with four different caking indices in the step 1 is 55-68wt.%.

The binder in the steps 2, 3 and 4 is an organic-inorganic composite binder, in which the inorganic binder accounts for 20-40wt.%, and the organic binder accounts for 60-80wt.%. The inorganic binder is selected from water glass; the organic binder is selected from deformed starch.

The composite caking coal reducing pellets for industrial silicon prepared above has a caking index of 60-80 and a cold strength of 8-14 MPa.

In the present invention, the silicon yield refers to the ratio of 1t to the silica mass (t) consumed to produce one ton of silicon. The silicon output rate=1t/unit consumption of silica*100%.

By adopting the process of the invention, the yield of silicon is 38.9%-43.1%, and the purity of the obtained industrial silicon is greater than or equal to 99.3%.

After optimization, the yield of silicon is 43.1%, and the purity of silicon is 99.6wt%.

The beneficial effects of the present invention are:

1. In the present invention, coking coal is used as carbonaceous raw material, and a combination of different particle sizes and bonding properties is used to mix and stir to form a porous honeycomb structure layer by layer, and the smaller the particle size, the higher the bonding effect, so that the particles exist A large number of voids help to fully disperse in smelting and ensure full combustion of carbon materials.

2. The present invention increases the pellet density, porosity and fixed carbon content by roasting coking coal, and at the same time increases the temperature to make the honeycomb-shaped reduced pellets reach a certain cohesion index, and finally forms a porous honeycomb structure with higher strength , can ensure the permeability of the charge in smelting, reduce the carbon burning loss rate by 8%-12%, and increase the silicon yield rate by 4%-8%.

3. The honeycomb-shaped reducing pellets for industrial silicon prepared by the present invention release a large amount of volatile matter after roasting, the reactivity reaches more than 99% at 1000°C, the fixed carbon content reaches more than 75%, the volatile matter content is 12-20%, and the ash content The low content is less than 4%, the specific resistance is 3000-4000Ω·m, the cold strength reaches 8-14MPa, and the bonding index reaches 60-80, which can be completely suitable for industrial silicon.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the content described.

In steps 3 and 4 of the embodiment of the present invention, all low-caking coals and the low-caking coals in steps 1 and 2 of the corresponding embodiment are the same batch.

Example 1

The honeycomb-shaped reduction pellets for industrial silicon have a fixed carbon content of 77.4wt.%, a volatile content of 19wt.%, an ash content of 3.6wt.%, a specific resistance of 3500Ω·m, a knot index G of 70, and a cold strength of the pellets. up to 11MPa.

The method for preparing honeycomb reducing pellets for industrial silicon comprises the following steps:

Step 1. Firstly, four kinds of coals with different caking indices are crushed to the required particle size; among them, the particle size of low caking coal is 10 mm, and the caking index is 5; the particle size of medium caking coal is 0.3 mm, and the caking index is 5. The index is 55; the particle size of the high caking coal used in the first cladding layer is 0.06mm, and the caking index is 75; the particle diameter of the high caking coal used in the second cladding layer is 0.02mm, and the caking index is 93; for the preparation of The mass ratio of the low-viscosity coal used in the central honeycomb pellets, the medium-caused coal used to prepare the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 45:35:25: 25.

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to mass ratio, medium-causity coal: low-viscosity coal = 45:35, then add 10wt.% water, 1wt% binder and stir until obvious Block, shaped into a central honeycomb pellet with a diameter of 25mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 20wt% in the organic-inorganic composite binder, the organic binder accounts for 80wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

Step 3, mix the low-viscosity coal and the high-viscosity coal used in the first cladding layer, according to the mass ratio, low-viscosity coal: high-viscosity coal used in the first cladding layer = 40:60, after mixing evenly, add the Central honeycomb pellets, then add 10wt.% water, 1wt% binder and stir until obviously agglomerated, and the central honeycomb pellets in step 2 are overmolded into agglomerate particles with a diameter of 40mm; wherein the binder is Organic-inorganic composite binder, the inorganic binder accounts for 20wt% in the organic-inorganic composite binder, the organic binder accounts for 80wt%, the inorganic binder is water glass, and the organic binder is modified starch;

Step 4, mix the low-viscosity coal and the high-viscosity coal used in the second cladding layer according to the mass ratio, low-viscosity coal: high-viscosity coal used in the second cladding layer = 35:65, mix and stir evenly, then add the Agglomerate particles, then add 10wt.% of water, 1wt% binder and stir until obvious agglomeration, the center honeycomb pellet in step 3 is overmolded into agglomerate particles with a diameter of 50mm; wherein the binder is an organic Inorganic composite binder, in the organic-inorganic composite binder, the inorganic binder accounts for 20wt%, the organic binder accounts for 80wt%, the inorganic binder is water glass, and the organic binder is modified starch;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 500° C. for 3 hours in isolation from air and low-temperature roasting, and cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

Among the raw materials used:

The fixed carbon content of low caking coal is 63wt.%, the volatile content is 32.6wt.%, and the ash content is 1wt.%.

The fixed carbon content of medium caking coal is 59wt.%, the volatile content is 36.7wt.%, and the ash content is 1.2wt.%.

The high caking coal used in the first cladding layer has a fixed carbon content of 55wt.%, a volatile content of 38.2wt.%, and an ash content of 0.5wt.%.

The high caking coal used in the second cladding layer has a fixed carbon content of 64wt.%, a volatile content of 32.2wt.%, and an ash content of 0.9wt.%.

Break 200kg of silica (99.5% SiO ₂ , 0.05% Al ₂ O ₃ , 0.03% Fe ₂ O ₃ , 0.05% CaO) into chunks with a particle size of 25-100 mm, and after cleaning and screening, reduce it with 103 kg of the above composite carbonaceous Mix the agent evenly, add it to the submerged arc furnace for smelting (the melting temperature is 2200 degrees Celsius), the silicon yield is 40.4%, and the composition of industrial silicon products is Si>99.4Wt.%, Fe≤0.19Wt.%, Al≤ 0.09Wt.%, Ca≤0.05Wt.%.

Example 2

The honeycomb-shaped reduction pellets for industrial silicon have a fixed carbon content of 77.5wt.%, a volatile content of 20wt.%, an ash content of 2.8wt.%, a specific resistance of 4000Ω·m, a knot index G of 74, and a cold strength of the pellets. Reach 13MPa.

The method for preparing honeycomb reducing pellets for industrial silicon comprises the following steps:

Step 1. Firstly, four kinds of coals with different caking indices are crushed to the required particle size; among them, the particle size of low caking coal is 8mm, and the caking index is 10; the particle size of medium caking coal is 0.35mm, and the caking index is The index is 60; the particle size of high caking coal used in the first cladding layer is 0.065mm, and the caking index is 80; the particle diameter of high caking coal used in the second cladding layer is 0.037mm, and the caking index is 90. The mass ratio of the low-viscosity coal used to prepare the central honeycomb pellets, the medium-caused coal used to prepare the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 40:30 :25:20.

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to the mass ratio, medium-causity coal: low-viscosity coal = 40:30, then add 11wt.% water, 1wt% binder and stir until obvious knot Block, shaped into a central honeycomb pellet with a diameter of 30mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 30wt% in the organic-inorganic composite binder, the organic binder accounts for 70wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

Step 3, mix the low-viscosity coal and the high-viscosity coal used in the first cladding layer by mass ratio, low-viscosity coal: high-viscosity coal used in the first cladding layer = 35:65, mix and stir evenly, then add the Central honeycomb pellets, then add 11wt.% of water, 1wt% binder and stir until obviously agglomerated, and the central honeycomb pellets in step 2 are overmolded into agglomerate particles with a diameter of 45mm; wherein the binder is Organic-inorganic composite binder, the inorganic binder accounts for 30wt% in the organic-inorganic composite binder, the organic binder accounts for 70wt%, the inorganic binder is water glass, and the organic binder is modified starch;

Step 4, mix the low-viscosity coal and the high-viscosity coal used in the second cladding layer, according to the mass ratio, low-viscosity coal: high-viscosity coal used in the second cladding layer = 20:80, after mixing evenly, add the Agglomerate granule, then add 11wt.% of water, 1wt% binder and stir until obvious agglomeration, and the central honeycomb pellet in step 3 is overmolded into agglomerate granule with a diameter of 55mm; wherein the binder is an organic Inorganic composite binder, in the organic-inorganic composite binder, the inorganic binder accounts for 30wt%, the organic binder accounts for 70wt%, the inorganic binder is water glass, and the organic binder is modified starch;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 550° C. for 2 hours in the absence of air and low-temperature roasting, and cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

Among the raw materials used:

The fixed carbon content of low caking coal is 64wt.%, the volatile content is 34.6wt.%, and the ash content is 0.8wt.%.

The fixed carbon content of medium caking coal is 60wt.%, the volatile content is 35.7wt.%, and the ash content is 1wt.%.

The high caking coal used in the first cladding layer has a fixed carbon content of 56wt.%, a volatile content of 37.2wt.%, and an ash content of 0.4wt.%.

The high caking coal used in the second coating layer has a fixed carbon content of 58wt.%, a volatile content of 36.2wt.%, and an ash content of 0.6wt.%.

Break 200kg of silica (99.5% SiO ₂ , 0.05% Al ₂ O ₃ , 0.03% Fe ₂ O ₃ , 0.05% CaO) into chunks with a particle size of 25-100 mm, and after cleaning and screening, reduce it with 103 kg of the above composite carbonaceous Mix the agent evenly, add it to the submerged arc furnace for smelting (the melting temperature is 2200 degrees Celsius), the silicon yield is 43.1%, and the composition of industrial silicon products is Si>99.6Wt.%, Fe≤0.19Wt.%, Al≤ 0.09Wt.%, Ca≤0.05Wt.%.

Example 3

The honeycomb-shaped reduction pellets for industrial silicon have a fixed carbon content of 78.5wt.%, a volatile content of 18.2wt.%, an ash content of 3.3wt.%, a specific resistance of 3800Ω·m, a knot index G of 68, and a cold pellet. The strength reaches 10MPa.

The method for preparing honeycomb reducing pellets for industrial silicon comprises the following steps:

Step 1. Firstly, four kinds of coals with different caking indices are crushed to the required particle size; among them, the particle size of low caking coal is 12 mm, and the caking index is 13; the particle size of medium caking coal is 0.5 mm, and the caking index is 13 The index is 61; the particle size of high caking coal used in the first cladding layer is 0.08mm, and the caking index is 82; the particle diameter of high caking coal used in the second cladding layer is 0.045mm, and the caking index is 89. The mass ratio of the low-viscosity coal used to prepare the central honeycomb pellets, the medium-caused coal used to prepare the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 50:40 :30:25.

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to the mass ratio, medium-causity coal: low-viscosity coal = 50:40, then add 12wt.% water, 1wt% binder and stir until obvious knot Block, shaped into a central honeycomb pellet with a diameter of 30mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 20wt% in the organic-inorganic composite binder, the organic binder accounts for 80wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

Step 3, mix the low-viscosity coal and the high-viscosity coal used in the first cladding layer, according to the mass ratio, low-viscosity coal: high-viscosity coal used in the first cladding layer = 45:55, after mixing evenly, add the Central honeycomb pellets, then add 12wt.% water, 1wt% binder and stir until obvious agglomeration, and the central honeycomb pellets in step 2 are overmolded into agglomerate particles with a diameter of 48mm; wherein the binder is Organic-inorganic composite binder, the inorganic binder accounts for 20wt% in the organic-inorganic composite binder, the organic binder accounts for 80wt%, the inorganic binder is water glass, and the organic binder is modified starch;

Step 4, mix the low-viscosity coal and the high-viscosity coal used in the second coating layer according to the mass ratio, low-viscosity coal: high-viscosity coal used in the second coating layer = 40:60, after mixing evenly, add the Agglomerate granules, then add 12wt.% water, 1wt% binder and stir until obvious agglomeration, and the central honeycomb pellet in step 3 is overmolded into agglomerate particles with a diameter of 60mm; wherein the binder is an organic Inorganic composite binder, in the organic-inorganic composite binder, the inorganic binder accounts for 20wt%, the organic binder accounts for 80wt%, the inorganic binder is water glass, and the organic binder is modified starch;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 500° C. for 4 hours in the absence of air and low-temperature roasting, and cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

Among the raw materials used:

The fixed carbon content of low caking coal is 59wt.%, the volatile content is 35.6wt.%, and the ash content is 1.1wt.%.

The fixed carbon content of medium caking coal is 63wt.%, the volatile content is 34.7wt.%, and the ash content is 1.2wt.%.

The high caking coal used in the first cladding layer has a fixed carbon content of 62wt.%, a volatile content of 36.2wt.%, and an ash content of 0.6wt.%.

The high caking coal used in the second cladding layer has a fixed carbon content of 64wt.%, a volatile content of 33.2wt.%, and an ash content of 0.4wt.%.

Break 200kg of silica (99.5% SiO ₂ , 0.05% Al ₂ O ₃ , 0.03% Fe ₂ O ₃ , 0.05% CaO) into chunks with a particle size of 25-100 mm, and after cleaning and screening, reduce it with 103 kg of the above composite carbonaceous Mix the agent evenly, add it to the submerged arc furnace for smelting (the melting temperature is 2200 degrees Celsius), the silicon yield is 39.9%, and the composition of industrial silicon products is Si>99.4Wt.%, Fe≤0.19Wt.%, Al≤ 0.09Wt.%, Ca≤0.05Wt.%.

Example 4

The honeycomb-shaped reduction pellets for industrial silicon have a fixed carbon content of 80.4wt.%, a volatile content of 16wt.%, ash content of 3.6wt.%, a specific resistance of 3200Ω·m, a knot index G of 60, and a cold strength of the pellets. Reach 8MPa.

The method for preparing honeycomb reducing pellets for industrial silicon comprises the following steps:

Step 1. Firstly, four kinds of coals with different caking indexes are crushed to the required particle size; the particle size of low caking coal is 13mm, and the caking index is 8; the particle diameter of medium caking coal is 0.45mm, and the caking index is 8. The index is 56; the particle size of high caking coal used in the first cladding layer is 0.06mm, and the caking index is 70; the particle diameter of high caking coal used in the second cladding layer is 0.035mm, and the caking index is 88. The mass ratio of the low-viscosity coal used to prepare the central honeycomb pellets, the medium-viscosity coal used to prepare the central honeycomb pellets, the high-viscosity coal used in the first cladding layer, and the high-constraint coal used in the second cladding layer is 45:40 :30:20.

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to the mass ratio, medium-catheter coal: low-viscosity coal = 45:40, then add 8wt.% of water, 1wt% of binder and stir until obvious knot Block, shaped into a central honeycomb pellet with a diameter of 30mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 30wt% in the organic-inorganic composite binder, the organic binder accounts for 70wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

Step 3, mix the low-viscosity coal and the high-viscosity coal used in the first cladding layer by mass ratio, low-viscosity coal: high-viscosity coal used in the first cladding layer = 50:50, mix and stir evenly, add the Central honeycomb pellets, then add 8wt.% water, 1wt% binder and stir until obvious agglomeration, and the central honeycomb pellets in step 2 are overmolded into agglomerate particles with a diameter of 45mm; wherein the binder is Organic-inorganic composite binder, the inorganic binder accounts for 30wt% in the organic-inorganic composite binder, the organic binder accounts for 70wt%, the inorganic binder is water glass, and the organic binder is modified starch;

Step 4, mix the low-viscosity coal and the high-viscosity coal used in the second coating layer according to the mass ratio, low-viscosity coal: high-viscosity coal used in the second coating layer = 40:60, after mixing evenly, add the Agglomerate granules, then add 8wt.% water, 1wt% binder and stir until obvious agglomeration, and the central honeycomb pellet in step 3 is overmolded into agglomerate particles with a diameter of 50mm; wherein the binder is an organic Inorganic composite binder, in the organic-inorganic composite binder, the inorganic binder accounts for 30wt%, the organic binder accounts for 70wt%, the inorganic binder is water glass, and the organic binder is modified starch;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 400° C. for 4 hours in the absence of air and low-temperature roasting, and then cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

Among the raw materials used:

The fixed carbon content of low caking coal is 68wt.%, the volatile content is 30.6wt.%, and the ash content is 0.6wt.%.

The fixed carbon content of medium caking coal is 60wt.%, the volatile content is 34.7wt.%, and the ash content is 1.8wt.%.

The high caking coal used in the first cladding layer has a fixed carbon content of 59wt.%, a volatile content of 36.2wt.%, and an ash content of 0.8wt.%.

The high caking coal used in the second cladding layer has a fixed carbon content of 63wt.%, a volatile content of 33.2wt.%, and an ash content of 0.4wt.%.

Break 200kg of silica (99.5% SiO ₂ , 0.05% Al ₂ O ₃ , 0.03% Fe ₂ O ₃ , 0.05% CaO) into chunks with a particle size of 25-100 mm, and after cleaning and sieving, reduce it with 100 kg of the above composite carbonaceous Mix the agent evenly, add it to the submerged arc furnace for smelting (the melting temperature is 2200 degrees Celsius), the silicon yield is 38.9%, and the composition of industrial silicon products is Si>99.3Wt.%, Fe≤0.19Wt.%, Al≤ 0.09Wt.%, Ca≤0.05Wt.%.

Example 5

The honeycomb-shaped reduction pellets for industrial silicon have a fixed carbon content of 81.5wt.%, a volatile content of 14.8wt.%, an ash content of 3.7wt.%, a specific resistance of 3400Ω·m, a knot index G of 80, and a cold pellet. The strength reaches 14MPa.

The method for preparing honeycomb reducing pellets for industrial silicon comprises the following steps:

Step 1. Firstly, four kinds of coals with different caking indices are crushed to the required particle size; among them, the particle size of low caking coal is 12mm, and the caking index is 15; the particle size of medium caking coal is 0.35mm, and the caking index is The index is 65; the particle size of high caking coal used in the first cladding layer is 0.075mm, and the caking index is 75; the particle diameter of high caking coal used in the second cladding layer is 0.025mm, and the caking index is 93. The mass ratio of the low-viscosity coal used to prepare the central honeycomb pellets, the medium-viscosity coal used to prepare the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 50:30 :30:30.

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to the mass ratio, medium-causity coal: low-viscosity coal = 50:30, then add 10wt.% water, 1wt% binder and stir until obvious knot Block, shaped into a central honeycomb pellet with a diameter of 28mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 40wt% in the organic-inorganic composite binder, the organic binder accounts for 60wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

Step 3, mix the low-viscosity coal and the high-viscosity coal used in the first cladding layer, according to the mass ratio, low-viscosity coal: high-viscosity coal used in the first cladding layer = 30:70, after mixing evenly, add the Central honeycomb pellets, then add 10wt.% water, 1wt% binder and stir until obviously agglomerated, and the central honeycomb pellets in step 2 are overmolded into agglomerate particles with a diameter of 50mm; wherein the binder is Organic-inorganic composite binder, the inorganic binder accounts for 40wt% in the organic-inorganic composite binder, the organic binder accounts for 60wt%, the inorganic binder is water glass, and the organic binder is modified starch;

Step 4, mix the low-viscosity coal and the high-viscosity coal used in the second cladding layer according to the mass ratio, low-viscosity coal: high-viscosity coal used in the second cladding layer = 35:65, mix and stir evenly, then add the Agglomerate granule, then add 10wt.% water, 1wt% binding agent and stir until obvious agglomeration, the central honeycomb pellet in step 3 is overmolded into the agglomerate particle of diameter 60mm; Wherein binding agent is organic Inorganic composite binder, in the 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;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 600° C. for 2 hours in the absence of air and low-temperature roasting, and cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

Among the raw materials used:

The fixed carbon content of low caking coal is 65wt.%, the volatile content is 31.6wt.%, and the ash content is 1.4wt.%.

The fixed carbon content of medium caking coal is 63wt.%, the volatile content is 33.7wt.%, and the ash content is 1wt.%.

The high caking coal used in the first cladding layer has a fixed carbon content of 60wt.%, a volatile content of 35.2wt.%, and an ash content of 0.7wt.%.

The high caking coal used in the second cladding layer has a fixed carbon content of 68wt.%, a volatile content of 30.2wt.%, and an ash content of 0.6wt.%.

Break 200kg of silica (99.5% SiO ₂ , 0.05% Al ₂ O ₃ , 0.03% Fe ₂ O ₃ , 0.05% CaO) into chunks with a particle size of 25-100 mm, and after cleaning and screening, reduce it with 103 kg of the above composite carbonaceous Mix the agent evenly, add it to the submerged arc furnace for smelting (the melting temperature is 2200 degrees Celsius), the silicon yield is 41.5%, and the composition of industrial silicon products is Si>99.5Wt.%, Fe≤0.19Wt.%, Al≤ 0.09Wt.%, Ca≤0.05Wt.%.

Example 6

The honeycomb-shaped reduction pellets for industrial silicon have a fixed carbon content of 79.8wt.%, a volatile content of 16.8wt.%, an ash content of 3.4%, a specific resistance of 3700Ω·m, a knot index G of 74, and a pellet cold strength of 14MPa.

The method for preparing honeycomb reducing pellets for industrial silicon comprises the following steps:

Step 1. First, four kinds of coal with different caking indices are crushed to the required particle size; the particle size of low caking coal is 7mm, and the caking index is 14; the particle size of medium caking coal is 0.35mm, caking index is 14; The index is 60; the particle size of high caking coal used in the first cladding layer is 0.065mm, and the caking index is 74; the particle diameter of high caking coal used in the second cladding layer is 0.045mm, and the caking index is 96. The mass ratio of the low-viscosity coal used to prepare the central honeycomb pellets, the medium-caused coal used to prepare the central honeycomb pellets, the high-viscosity coal used in the first coating layer and the high-viscosity coal used in the second coating layer is 40:35 :30:30.

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to the mass ratio, medium-causity coal: low-viscosity coal = 40:35, then add 12wt.% of water, 1wt% of binder and stir until obvious knot Block, shaped into a central honeycomb pellet with a diameter of 27mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 30wt% in the organic-inorganic composite binder, the organic binder accounts for 70wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

Step 3, mix the low-viscosity coal and the high-viscosity coal used in the first cladding layer by mass ratio, low-viscosity coal: high-viscosity coal used in the first cladding layer = 35:65, mix and stir evenly, then add the Central honeycomb pellets, then add 12wt.% water, 1wt% binder and stir until obvious agglomeration, and the central honeycomb pellets in step 2 are overmolded into agglomerate particles with a diameter of 48mm; wherein the binder is Organic-inorganic composite binder, the inorganic binder accounts for 30wt% in the organic-inorganic composite binder, the organic binder accounts for 70wt%, the inorganic binder is water glass, and the organic binder is modified starch;

Step 4, mix the low-viscosity coal and the high-viscosity coal used in the second coating layer according to the mass ratio, low-viscosity coal: high-viscosity coal used in the second coating layer = 30:70, mix and stir evenly, and then add the Agglomerate granules, then add 12wt.% water, 1wt% binding agent and stir until obvious agglomeration, and the central honeycomb pellet in step 3 is overmolded into agglomerate particles with a diameter of 58mm; wherein the binding agent is an organic Inorganic composite binder, in the organic-inorganic composite binder, the inorganic binder accounts for 30wt%, the organic binder accounts for 70wt%, the inorganic binder is water glass, and the organic binder is modified starch;

In step 5, the agglomerate particles formed in step 4 are placed at a temperature of 550° C. for 3 hours in the absence of air and low-temperature roasting, and then cooled to room temperature with the furnace to obtain honeycomb-shaped reduced pellets for industrial silicon.

Among the raw materials used:

The fixed carbon content of low caking coal is 59wt.%, the volatile content is 34.6wt.%, and the ash content is 1.8wt.%.

The fixed carbon content of medium caking coal is 60wt.%, the volatile content is 35.7wt.%, and the ash content is 0.7wt.%.

The high caking coal used in the first cladding layer has a fixed carbon content of 65wt.%, a volatile content of 33.2wt.%, and an ash content of 0.4wt.%.

The high caking coal used in the second cladding layer has a fixed carbon content of 59wt.%, a volatile content of 35.2wt.%, and an ash content of 0.8wt.%.

Break 200kg of silica (99.5% SiO ₂ , 0.05% Al ₂ O ₃ , 0.03% Fe ₂ O ₃ , 0.05% CaO) into chunks with a particle size of 25-100 mm, and after cleaning and sieving, reduce it with 100 kg of the above composite carbonaceous Mix the agent evenly, add it to the submerged arc furnace for smelting (the melting temperature is 2200 degrees Celsius), the silicon yield is 42.7%, and the composition of industrial silicon products is Si>99.6Wt.%, Fe≤0.19Wt.%, Al≤ 0.09Wt.%, Ca≤0.05Wt.%.

Comparative example 1

Others are consistent with Example 1, except that 4 kinds of coals are directly mixed; the result is: the silicon yield is 32.5%, and the composition of industrial silicon products is 87.1Wt.% Si.

Comparative example 2

Others are consistent with Example 1, the difference is:

Step 1, firstly crush three kinds of coal with different caking index to the required particle size; among them, the particle size of low caking coal is 10mm, caking index is 5; the particle size of high caking coal used in the first cladding layer is 0.06mm, caking index is 75; particle size of high caking coal used in the second cladding layer is 0.02mm, caking index 93; low caking coal used to prepare central honeycomb pellets, high The mass ratio of caking coal and high caking coal used in the second cladding layer is 45:25:25.

Step 2, add 10wt.% water and 1wt% binder to the medium caking coal and stir until it is obviously agglomerated, forming a central honeycomb pellet with a diameter of 25mm; wherein the binder is an organic-inorganic composite binder, an organic In the inorganic composite binder, the inorganic binder accounts for 20wt%, the organic binder accounts for 80wt%, the inorganic binder is water glass, and the organic binder is modified starch;

The operation of steps 3, 4, 5 and parameters are consistent with embodiment 1;

The result is: the yield of silicon is 35.1%, and the composition of industrial silicon products is 96.4wt.% of Si.

Comparative example 3

Others are consistent with Example 1, the difference is:

Step 2, add low-viscosity coal to medium-causity coal, mix and stir evenly according to the mass ratio, medium-causity coal: low-viscosity coal = 20:40, then add 10wt.% water, 1wt% binder and stir until obvious knot Block, shaped into a central honeycomb pellet with a diameter of 25mm; wherein the binder is an organic-inorganic composite binder, the inorganic binder accounts for 20wt% in the organic-inorganic composite binder, the organic binder accounts for 80wt%, and the inorganic binder The agent is water glass, and the organic binder is modified starch;

The operation and parameters of steps 1, 3, 4, 5 are consistent with Example 1;

The result is: the yield of silicon is 36.2%, and the composition of industrial silicon products is 97.1wt.%.

Comparative example 4

Others are consistent with Example 1, the difference is:

No low-viscosity coal is added in step 3; the result is: the yield of silicon is 34.3%, and the composition of industrial silicon products is 95.7wt.% of Si.

Comparative example 5

Others are consistent with Example 1, the difference is:

No low-viscosity coal was added in step 4; the result was: the yield of silicon was 36.8%, and the composition of industrial silicon products was 98.3wt.% of Si.

The specific embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments, and various changes can also be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art .

Claims (10)

1. The preparation method of the honeycomb-shaped reduction pellet for the industrial silicon is characterized by comprising the following steps of:

step one preparation of center honeycomb pellets

The raw materials used for the central honeycomb pellet comprise low-viscosity coal and medium-viscosity coal, wherein the particle size of the low-viscosity coal is 5-15mm, the bonding index is less than or equal to 20, the particle size of the medium-viscosity coal is 0.2-0.6mm, and the bonding index is 50-65;

when the central honeycomb pellets are prepared, the mass ratio of the low-viscosity coal to the medium-viscosity coal is 40-50:30-40;

adding low-viscosity coal into medium-viscosity coal, mixing, stirring uniformly, adding 8-12 wt.% of water, and 0.8-1.2wt.%, preferably 1wt.% of binder, stirring until the binder is obviously agglomerated, and forming into central honeycomb pellets with the diameter of 20-30 mm;

step two cladding

Selecting high-viscosity coal with different particle sizes and binding indexes, and coating the central honeycomb pellets layer by layer; coating a 1 st coating layer on the central honeycomb pellet, coating a 2 nd coating layer on the 1 st coating layer, and so on, coating an i+1 th coating layer on the i th coating layer; obtaining formed agglomerate particles;

wherein i is a positive integer of 1 or more; the bonding index of the high-viscosity coal used by the ith coating layer is smaller than that of the high-viscosity coal used by the (i+1) th coating layer; the diameter of the high-viscosity coal used by the ith coating layer is larger than the viscosity diameter of the high-viscosity coal used by the (i+1) th coating layer; the diameter of the high-viscosity coal used by the ith coating layer is smaller than that of the medium-viscosity coal used by the central honeycomb pellet;

wherein, the mass ratio of the low-viscosity coal used for the center honeycomb pellet to the high-viscosity coal used for the first coating layer of the medium-viscosity coal used for the center honeycomb pellet is 40-50:30-40:20-30;

the mass ratio of the high-viscosity coal used for the first coating layer to the high-viscosity coal used for the second coating layer is 20-30:20-30;

the grain diameter of the high-viscosity coal used for the first coating layer is 0.05-0.1mm, and the bonding index is 70-85; the particle size of the high-viscosity coal used for the second coating layer is 0.02-0.05mm, and the bonding index is more than 85;

and thirdly, placing the agglomerate particles formed in the second step into an air-isolated low-temperature roasting furnace at 400-600 ℃ for 2-4 hours, and cooling the mixture to room temperature along with a furnace to obtain the honeycomb-shaped reduction pellets for the industrial silicon.

2. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: when any coating layer is prepared, low-viscosity coal is introduced; the granularity and the bonding index of the introduced low-viscosity coal are consistent with those of the low-viscosity coal used for preparing the central honeycomb pellets, namely, when any coating layer is prepared, the low-viscosity coal is introduced; the particle size of the low-viscosity coal is 5-15mm, and the caking index is less than or equal to 20.

3. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: when any coating layer is prepared, the mass ratio of the introduced low-viscosity coal to the high-viscosity coal used for the coating layer is 20-50:50-80.

4. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: in the preparation of the 1 st coating layer, the mass ratio of the introduced low-viscosity coal to the high-viscosity coal used for the layer is 20-50:50-80. Preferably 30-50:50-70.

5. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: in the preparation of the coating layer 2, the mass ratio of the introduced low-viscosity coal to the high-viscosity coal used for the coating layer is 20-50:50-80. Preferably 20-40:60-80.

6. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: the particle size of the low-viscosity coal used for the central honeycomb pellet is 7mm, the bonding index is 5, the particle size of the medium-viscosity coal used is 0.3mm, and the bonding index is 55; the particle size of the high-viscosity coal used for the first coating layer is 0.06mm, and the bonding index is 75; the particle size of the high-viscosity coal used for the second coating layer is 0.025mm, and the bonding index is 90.

7. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: the mass ratio of the low-viscosity coal used for the center honeycomb pellets, the medium-viscosity coal used for the center honeycomb pellets, the high-viscosity coal used for the first coating layer and the high-viscosity coal used for the second coating layer is 45:30:30:25.

8. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps:

the particle size of the low-viscosity coal used for the honeycomb pellets is 8mm, the bonding index is 15, the particle size of the medium-viscosity coal used is 0.3mm, and the bonding index is 60; the particle size of the high-viscosity coal used for the first coating layer is 0.065mm, and the bonding index is 70; the particle size of the high-viscosity coal used by the second coating layer is 0.044mm, the bonding index is 94, the mass ratio of the low-viscosity coal used by the center honeycomb pellet to the medium-viscosity coal used by the center honeycomb pellet to the high-viscosity coal used by the first coating layer to the high-viscosity coal used by the second coating layer is 40:35:25:25; or (b)

The particle size of the low-viscosity coal used for the central honeycomb pellet is 10mm, the bonding index is 10, the particle size of the medium-viscosity coal used is 0.4mm, and the bonding index is 64; the particle size of the high-viscosity coal used for the first coating layer is 0.075mm, and the bonding index is 80; the particle size of the high-viscosity coal used for the second coating layer is 0.037mm, the bonding index is 96, the mass ratio of the low-viscosity coal used for the center honeycomb pellet to the medium-viscosity coal used for the center honeycomb pellet to the high-viscosity coal used for the first coating layer to the high-viscosity coal used for the second coating layer is 50:35:30:25.

9. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: when i=2, it is prepared by the steps comprising:

step 1, firstly, respectively crushing four kinds of coals with different caking indexes into particles with required granularity; wherein the particle size of the low-viscosity coal is 6-12mm, and the caking index is 5-20; the particle size of the medium caking coal is 0.3-0.5mm, and the caking index is 55-65; the grain diameter of the high-viscosity coal used for the first coating layer is 0.06-0.1mm, and the bonding index is 70-85; the particle size of the high-viscosity coal used for the second coating layer is 0.02-0.045mm, and the bonding index is more than 85.

Step 2, adding low-viscosity coal into the medium-viscosity coal according to the mass ratio of 40-50: mixing and stirring evenly 30-40, adding 8-12 wt.% of water, and stirring 0.8-1.2wt.% of binder, preferably 1wt.% to obviously agglomerate, and forming into a central honeycomb pellet with the diameter of 20-30 mm;

step 3, mixing low-viscosity coal and high-viscosity coal used for the first coating layer according to a mass ratio of 30-50:50-70, adding the central honeycomb pellets in the step 2, adding 8-12 wt.% of water, and stirring 0.8-1.2wt.%, preferably 1wt.% of binder until the binder is obviously agglomerated, and coating the central honeycomb pellets in the step 2 into agglomerate particles with the diameter of 30-50 mm;

step 4, mixing the low-viscosity coal and the high-viscosity coal used for the second coating layer according to the mass ratio of 20-40:60-80, adding the agglomerate particles in the step 3, adding 8-12 wt.% of water, and stirring 0.8-1.2wt.%, preferably 1wt.% of binder until the binder is obviously agglomerated, and coating and molding the central honeycomb pellets in the step 3 into agglomerate particles with the diameter of 50-60 mm;

and 5, placing the agglomerate particles formed in the step 4 into an air-isolated low-temperature roasting furnace at 400-600 ℃ for 2-4 hours, and cooling to room temperature along with a furnace to obtain the honeycomb-shaped reduction pellets for the industrial silicon.

10. The method for preparing honeycomb reduction pellets for industrial silicon according to claim 1, wherein the method comprises the following steps: the fixed carbon content of the four coals with different caking indexes in the step 1 is 55 to 68wt.%;

the binder in the steps 2,3 and 4 is an organic-inorganic composite binder, wherein the inorganic binder accounts for 20-40 wt% of the composite binder, 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 obtained composite bonding coal reduction pellet for industrial silicon is 60-80, and the cold strength is 8-14 MPa.