Method for preparing reducing agent for silicon smelting by vacuum roasting coupled microbial upgrading of non-sticky high-sulfur bituminous coal

Abstract

The present application relates to a kind of vacuum roasting coupling microbial upgrading no-bonding high-sulfur bituminous coal preparation silicon smelting reducing agent method, belong to industrial silicon smelting composite reducing agent technical field.The present application mixes even with bituminous coal powder and corn cob powder and obtains mixture A, hydrogen peroxide solution is added in mixture A and grinds and mixes evenly and obtains mixture B;Mixture B is placed in temperature 800~1200 ℃ under vacuum roasting 30~90min, with furnace cooling and obtains roasting mixture C;Deionized water, bacteria liquid and sodium silicate are added to roasting mixture C, and carry out microbial leaching at temperature 25~65 ℃ for 5~10h, and stratify after standing, remove supernatant;Repeat microbial leaching step until supernatant is neutral, solid-liquid separation, and solid drying obtains low-sulfur composite reducing agent.The low-sulfur composite reducing agent obtained by the present application reaches 91.2~93.7%, and the caking index is 28~53, and the reaction activation energy is 13.4~17.7KJ / mol, meet the requirements of industrial silicon composite reducing agent.

Description

Technical Field

[0001] This invention relates to a method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading, belonging to the technical field of composite reducing agents for industrial silicon smelting. Background Technology

[0002] China has relatively abundant coal resources, but the amount of high-rank coal with high utilization value, high calorific value, low ash content and low impurity content is relatively small. However, low-rank coal with low industrial utilization value accounts for about 50% of my country's coal resources, resulting in the phenomenon of "idle" low-rank coal, which leads to the imbalance of the use cost of high-rank coal and the distribution of coal resources.

[0003] Currently, the carbonaceous reducing agents used in silicon smelting mainly include petroleum coke, charcoal, and coal, with coal accounting for the majority. Due to the continuous depletion of high-quality coal resources in my country, high-rank coal is facing high prices and resource scarcity. Furthermore, according to relevant statistics, over 80% of the SO2 emitted into the atmosphere in my country each year comes from coal combustion. Therefore, research on upgrading low-rank coal (especially high-sulfur bituminous coal) is essential, offering significant social and economic benefits and providing theoretical support for the comprehensive high-value application of coal resources. Research on desulfurization technology for high-sulfur bituminous coal has been reported. Patent number ZL2014101802599 proposes a biological desulfurization method for coal, with a desulfurization cycle of up to 10 days, but its desulfurization rate is only 57.8%. Patent application number 201710021693.6 proposes a microwave-assisted desulfurization method for low-quality coal. This method involves adding nitric acid, aluminum chloride, and a surfactant to a high-sulfur coal sample, followed by microwave irradiation for desulfurization, and then adding urea peroxide for further microwave irradiation for further oxidation and desulfurization. However, this technology only achieves a final desulfurization rate of 67.6%. Summary of the Invention

[0004] To address the issues of low industrial utilization value and high SO2 production from the combustion of low-rank, non-sticky, high-sulfur bituminous coal, this invention proposes a method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal using vacuum roasting coupled with microbial upgrading. Specifically, waste corn cob biomass is used as an additive. Through vacuum roasting, alkali metals from the corn cob migrate more rapidly into the pores of the high-sulfur coal, further increasing the reaction rate of the mixture, lowering the activation energy, and promoting the decomposition of CS bonds by organic acids in the corn cob. Simultaneously, the generated -OH groups effectively alter the internal structure of the organic matter, improving the binding index of the composite reducing agent. This invention also couples microbial desulfurization technology to specifically remove inorganic sulfur from bituminous coal, reducing the total sulfur content to the desired level. Adding an appropriate amount of sodium silicate to the microbial leaching system allows for sufficient contact between the microorganisms and pyrite, resulting in a more significant oxidative desulfurization effect.

[0005] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0006] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to obtain bituminous coal powder and corn cob powder respectively.

[0007] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B.

[0008] (3) Mixture B is placed in a vacuum calcination at a temperature of 800-1200℃ for 30-90 min, and then cooled in the furnace to obtain calcined mixture C;

[0009] (4) Add deionized water, bacterial solution and sodium silicate to the calcination mixture C, and carry out microbial leaching at a temperature of 25-65℃ for 5-10 hours. Let it stand and separate into layers, and remove the supernatant. Repeat the microbial leaching step until the supernatant is neutral, separate the solid and liquid, and dry the solid to obtain a low-sulfur composite reducing agent. The microorganisms in the bacterial solution are one or more of Thiobacillus thiooxidans, Thiobacillus thioreducans, Thiobacillus ferrooxidans and Thiobacillus denitrification.

[0010] The caking index of the non-caking high-sulfur bituminous coal in step (1) is 0-7, and the total sulfur content is 3%-8%; the total alkali metal content in the corn cob powder is 10-35 wt.%, the organic acid content is 10-25 wt%, and the organic matter content is 30-55 wt%.

[0011] Based on the mass of mixture A, in step (2), the bituminous coal accounts for 60-90% and the corn cob accounts for 10-40% of mixture A; the mass concentration of hydrogen peroxide solution is 3-8%, and the amount of hydrogen peroxide solution added is 4-10% of the mass of mixture A.

[0012] The vacuum degree of the vacuum calcination in step (3) is 10. -3 Pa ~ 100 Pa.

[0013] The concentration of the bacterial solution in step (4) is 1.6 × 10⁻⁶. 6 ~1.6×10 8 per mL.

[0014] In step (4), the liquid-to-solid ratio of deionized water to calcined mixture C is 8-15:1 (mL:g); the amount of bacterial solution added is 1-3% of the volume of deionized water, and the amount of sodium silicate added is 2-6 g / L.

[0015] The low-sulfur composite reducing agent in step (4) has a bonding index of 28-53, a desulfurization rate of 91.2-93.7%, and a reaction activation energy of 13.4-17.7 KJ / mol.

[0016] The beneficial effects of this invention are:

[0017] (1) This invention uses waste corn cobs as biomass additives and mixes them with non-sticky high-sulfur bituminous coal. The organic acids in the corn cobs can change the structure of organic sulfur in the bituminous coal, forming an easily decomposed sulfonic acid structure. Vacuum roasting accelerates the migration rate of alkali metals in the corn cobs into the bituminous coal microcrystals, improving the efficiency of organic sulfur removal. At the same time, organic sulfur generates -OH free radicals during structural transformation, which modifies the organic structure inside the corn cobs, enhances the stickiness of the corn cob powder, and improves the adhesion of the composite reducing agent, thus realizing the clean and efficient utilization of waste biomass.

[0018] (2) This invention utilizes pulsed electrodeposition with high anodic voltage and low cathode voltage to deposit large ceramic particles onto the alloy surface while small ceramic particles detach from the surface, which facilitates the formation of pores in the ceramic coating. Simultaneously, coupled microbial desulfurization technology further purifies high-sulfur bituminous coal, effectively improving the removal efficiency of inorganic sulfur (especially pyrite), ultimately converting inorganic sulfur into SO4. 2- ;

[0019] (3) The present invention uses vacuum roasting to remove organic sulfur, which can completely prevent the desulfurization product Na2S from reacting with water or oxygen, and effectively prevent the generation and emission of toxic gas SO2.

[0020] (4) The total sulfur content of the composite reducing agent obtained by the method of the present invention reaches the expected effect, the desulfurization rate is 91.2-93.7%, the bonding index is 28-53, and the reaction activation energy is 13.4-17.7 KJ / mol, which meets the requirements of composite reducing agent for industrial silicon.

[0021] (5) The process of the present invention is clean and efficient, environmentally friendly, with low investment cost and energy consumption, and strong production safety. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0023] Example 1: In this example, the caking index of the non-caking high-sulfur bituminous coal is 2, and the total sulfur content is 4%; the total content of alkali metal elements (K and Na) in the corn cob powder is 20wt.%, the content of organic acids (such as linoleic acid and oleic acid) is 10wt%, and the content of organic matter is 45wt%.

[0024] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0025] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to a particle size of less than 0.15 mm to obtain bituminous coal powder and corn cob powder respectively;

[0026] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. Based on the mass of mixture A, bituminous coal accounts for 90% and corn cob accounts for 10%. The mass concentration of hydrogen peroxide solution is 4%, and the amount of hydrogen peroxide solution added is 4% of the mass of mixture A.

[0027] (3) Mixture B was placed in a vacuum calcination at 1200℃ for 30 min, and then cooled in the furnace to obtain calcined mixture C; the vacuum degree of the vacuum calcination was 10. -3 Pa;

[0028] (4) Deionized water, bacterial solution (the microbial bacteria being *Thiobacillus thiocyanate*), and sodium silicate were added to the calcination mixture C. Microbial leaching was carried out at 25°C for 6 hours, followed by standing and separation. The supernatant was removed. The microbial leaching step was repeated until the supernatant was neutral. Solid-liquid separation was performed, and the solid was dried to obtain a low-sulfur composite reducing agent. The concentration of the bacterial solution was 1.6 × 10⁻⁶. 6 The liquid-to-solid ratio of deionized water to calcined mixture C is 8:1 (mL:g); the amount of bacterial solution added is 1% of the volume of deionized water, and the amount of sodium silicate added is 3 g / L.

[0029] In this embodiment, the low-sulfur composite reducing agent has a bonding index of 37, a desulfurization rate of 91.2%, and a reaction activation energy of 14.8 KJ / mol.

[0030] Comparative Example 1: The difference between this comparative example and Example 1 is that the vacuum calcination in step (3) is not included, and deionized water, bacterial solution (the microbial bacteria is Thiobacillus thiocyanate) and sodium silicate are directly added to mixture B for microbial leaching.

[0031] The composite reducing agent obtained in this comparative example has a bonding index of 12, a desulfurization rate of 41.6%, and a reaction activation energy of 19.9 KJ / mol.

[0032] Comparative Example 2: The difference between this comparative example and Example 1 is that: in step (4), no bacterial solution (the microbial bacteria is Thiobacillus thiocyanate) and sodium silicate are added, and only deionized water is used to leach the roasted mixture C;

[0033] The composite reducing agent obtained in this comparative example has a bonding index of 9, a desulfurization rate of 36.5%, and a reaction activation energy of 21.8 KJ / mol.

[0034] Example 2: In this example, the caking index of the non-caking high-sulfur bituminous coal is 4, and the total sulfur content is 5%; the total content of alkali metal elements (K and Na) in the corn cob powder is 15wt.%, the content of organic acids (such as linoleic acid and oleic acid) is 20wt%, and the content of organic matter is 30wt%.

[0035] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0036] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to a particle size of less than 0.15 mm to obtain bituminous coal powder and corn cob powder respectively;

[0037] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. Based on the mass of mixture A, bituminous coal accounts for 80% and corn cob accounts for 20%. The mass concentration of hydrogen peroxide solution is 6%, and the amount of hydrogen peroxide solution added is 8% of the mass of mixture A.

[0038] (3) Mixture B was placed in a vacuum calcination at 850℃ for 80 min and cooled in the furnace to obtain calcined mixture C; the vacuum degree of the vacuum calcination was 60 Pa;

[0039] (4) Deionized water, bacterial solution (the microbial bacteria being *Thiobacillus thiocyanate*), and sodium silicate were added to the calcination mixture C. Microbial leaching was carried out at 30°C for 5 hours, followed by standing and separation. The supernatant was removed. The microbial leaching step was repeated until the supernatant was neutral. Solid-liquid separation was performed, and the solid was dried to obtain a low-sulfur composite reducing agent. The concentration of the bacterial solution was 1.8 × 10⁻⁶. 6 The liquid-to-solid ratio of deionized water to calcined mixture C is 10:1 (mL:g); the amount of bacterial solution added is 1.5% of the volume of deionized water, and the amount of sodium silicate added is 5 g / L.

[0040] In this embodiment, the low-sulfur composite reducing agent has a bonding index of 53, a desulfurization rate of 92.5%, and a reaction activation energy of 13.4 KJ / mol.

[0041] Comparative Example 3: The difference between this comparative example and Example 2 is that the vacuum calcination in step (3) is not included, and deionized water, bacterial solution (the microbial bacteria is Thiobacillus thiocyanate) and sodium silicate are directly added to mixture B for microbial leaching;

[0042] The composite reducing agent obtained in this comparative example has a bonding index of 13, a desulfurization rate of 43.5%, and a reaction activation energy of 20.1 KJ / mol.

[0043] Comparative Example 4: The difference between this comparative example and Example 2 is that: in step (4), no bacterial solution (the microbial bacteria is Thiobacillus thiocyanate) and sodium silicate are added, and only deionized water is used to leach the calcined mixture C;

[0044] The composite reducing agent obtained in this comparative example has a bonding index of 10, a desulfurization rate of 39.2%, and a reaction activation energy of 20.8 KJ / mol.

[0045] Example 3: In this example, the caking index of the non-caking high-sulfur bituminous coal is 0, and the total sulfur content is 6%; the total content of alkali metal elements (K and Na) in the corn cob powder is 10 wt.%, the content of organic acids (such as linoleic acid and oleic acid) is 25 wt%, and the content of organic matter is 35 wt%.

[0046] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0047] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to a particle size of less than 0.15 mm to obtain bituminous coal powder and corn cob powder respectively;

[0048] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. Based on the mass of mixture A, bituminous coal accounts for 70% and corn cob accounts for 30%. The mass concentration of hydrogen peroxide solution is 3%, and the amount of hydrogen peroxide solution added is 7% of the mass of mixture A.

[0049] (3) Mixture B was placed in a vacuum calcination at 1000℃ for 60 min and cooled in the furnace to obtain calcined mixture C; the vacuum degree of the vacuum calcination was 80 Pa;

[0050] (4) Deionized water, bacterial solution (the microbial bacteria being *Thiobacillus thiooxidans*), and sodium silicate were added to the calcination mixture C. Microbial leaching was carried out at 65°C for 7 hours, followed by standing and separation. The supernatant was removed. The microbial leaching step was repeated until the supernatant was neutral. Solid-liquid separation was performed, and the solid was dried to obtain a low-sulfur composite reducing agent. The concentration of the bacterial solution was 2.0 × 10⁻⁶. 7 The liquid-to-solid ratio of deionized water to calcined mixture C is 15:1 (mL:g); the amount of bacterial solution added is 1.8% of the volume of deionized water, and the amount of sodium silicate added is 2 g / L.

[0051] In this embodiment, the low-sulfur composite reducing agent has a bonding index of 35, a desulfurization rate of 93.7%, and a reaction activation energy of 15.2 KJ / mol.

[0052] Comparative Example 5: The difference between this comparative example and Example 3 is that the vacuum calcination in step (3) is not included, and deionized water, bacterial solution (the microbial bacteria is Thiobacillus thiooxidans) and sodium silicate are directly added to mixture B for microbial leaching.

[0053] The composite reducing agent obtained in this comparative example has a bonding index of 20, a desulfurization rate of 57.8%, and a reaction activation energy of 19.3 KJ / mol.

[0054] Comparative Example 6: The difference between this comparative example and Example 3 is that: in step (4), no bacterial solution (the microbial bacteria is Thiobacillus thiooxidans) and sodium silicate are added, and only deionized water is used to leach the calcined mixture C;

[0055] The composite reducing agent obtained in this comparative example has a bonding index of 17, a desulfurization rate of 43.2%, and a reaction activation energy of 19.8 KJ / mol.

[0056] Example 4: In this example, the caking index of the non-caking high-sulfur bituminous coal is 1, and the total sulfur content is 8%; the total content of alkali metal elements (K and Na) in the corn cob powder is 30 wt.%, the content of organic acids (such as linoleic acid and oleic acid) is 15 wt%, and the content of organic matter is 40 wt%.

[0057] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0058] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to a particle size of less than 0.15 mm to obtain bituminous coal powder and corn cob powder respectively;

[0059] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. Based on the mass of mixture A, bituminous coal accounts for 60% and corn cob accounts for 40%. The mass concentration of hydrogen peroxide solution is 8%, and the amount of hydrogen peroxide solution added is 10% of the mass of mixture A.

[0060] (3) Mixture B was placed in a vacuum calcination at 1100℃ for 40 min and cooled in the furnace to obtain calcined mixture C; the vacuum degree of the vacuum calcination was 50 Pa.

[0061] (4) Deionized water, bacterial solution (the microbial strain being *Thiobacillus ferrooxidans*), and sodium silicate were added to the calcination mixture C. Microbial leaching was carried out at 50°C for 10 hours, followed by standing and separation. The supernatant was removed. The microbial leaching step was repeated until the supernatant was neutral. Solid-liquid separation was performed, and the solid was dried to obtain a low-sulfur composite reducing agent. The concentration of the bacterial solution was 1.6 × 10⁻⁶. 8 The liquid-to-solid ratio of deionized water to calcined mixture C is 12:1 (mL:g); the amount of bacterial solution added is 3% of the volume of deionized water, and the amount of sodium silicate added is 3 g / L.

[0062] In this embodiment, the low-sulfur composite reducing agent has a bonding index of 28, a desulfurization rate of 93.3%, and a reaction activation energy of 14.5 KJ / mol.

[0063] Comparative Example 7: The difference between this comparative example and Example 4 is that the vacuum calcination in step (3) is not included, and deionized water, bacterial solution (the microbial bacteria is ferrooxidizobacillus) and sodium silicate are directly added to mixture B for microbial leaching;

[0064] The composite reducing agent obtained in this comparative example has a bonding index of 15, a desulfurization rate of 48.7%, and a reaction activation energy of 18.4 KJ / mol.

[0065] Comparative Example 8: The difference between this comparative example and Example 4 is that: in step (4), no bacterial solution (the microbial bacteria is ferrooxidizobacillus) and sodium silicate are added, and only deionized water is used to leach the calcined mixture C;

[0066] The composite reducing agent obtained in this comparative example has a bonding index of 12, a desulfurization rate of 38.3%, and a reaction activation energy of 19.9 KJ / mol.

[0067] Example 5: In this example, the caking index of the non-caking high-sulfur bituminous coal is 3, and the total sulfur content is 3%; the total content of alkali metal elements (K and Na) in the corn cob powder is 35wt.%, the content of organic acids (such as linoleic acid and oleic acid) is 18wt%, and the content of organic matter is 55wt%.

[0068] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0069] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to a particle size of less than 0.15 mm to obtain bituminous coal powder and corn cob powder respectively;

[0070] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. Based on the mass of mixture A, bituminous coal accounts for 85% and corn cob accounts for 15%. The mass concentration of hydrogen peroxide solution is 5%, and the amount of hydrogen peroxide solution added is 6% of the mass of mixture A.

[0071] (3) Mixture B was placed in a vacuum calcination at 800℃ for 90 min and cooled in the furnace to obtain calcined mixture C; the vacuum degree of the vacuum calcination was 100 Pa;

[0072] (4) Deionized water, bacterial solution (the microbial strain being *Thiobacillus ferrooxidans*), and sodium silicate were added to the calcination mixture C. Microbial leaching was carried out at 45°C for 8 hours, followed by standing and separation. The supernatant was removed. The microbial leaching step was repeated until the supernatant was neutral. Solid-liquid separation was performed, and the solid was dried to obtain a low-sulfur composite reducing agent. The concentration of the bacterial solution was 5.0 × 10⁻⁶. 7The liquid-to-solid ratio of deionized water to calcined mixture C is 9:1 (mL:g); the amount of bacterial solution added is 2.5% of the volume of deionized water, and the amount of sodium silicate added is 4 g / L.

[0073] In this embodiment, the low-sulfur composite reducing agent has a bonding index of 43, a desulfurization rate of 91.9%, and a reaction activation energy of 17.7 KJ / mol.

[0074] Comparative Example 9: The difference between this comparative example and Example 5 is that the vacuum calcination in step (3) is not included, and deionized water, bacterial solution (the microbial bacteria is ferrooxidizobacillus) and sodium silicate are directly added to mixture B for microbial leaching;

[0075] The composite reducing agent obtained in this comparative example has a bonding index of 18, a desulfurization rate of 52.8%, and a reaction activation energy of 19.2 KJ / mol.

[0076] Comparative Example 10: The difference between this comparative example and Example 5 is that: in step (4), no bacterial solution (the microbial bacteria is ferrooxidizobacillus) and sodium silicate are added, and only deionized water is used to leach the calcined mixture C;

[0077] The composite reducing agent obtained in this comparative example has a bonding index of 11, a desulfurization rate of 48.5%, and a reaction activation energy of 21.1 KJ / mol.

[0078] Example 6: In this example, the caking index of the non-caking high-sulfur bituminous coal is 7, and the total sulfur content is 7%; the total content of alkali metal elements (K and Na) in the corn cob powder is 25 wt.%, the content of organic acids (such as linoleic acid and oleic acid) is 10 wt%, and the content of organic matter is 50 wt%.

[0079] A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading includes the following specific steps:

[0080] (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to a particle size of less than 0.15 mm to obtain bituminous coal powder and corn cob powder respectively;

[0081] (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. Based on the mass of mixture A, bituminous coal accounts for 75% and corn cob accounts for 25%. The mass concentration of hydrogen peroxide solution is 7%, and the amount of hydrogen peroxide solution added is 5% of the mass of mixture A.

[0082] (3) Mixture B was placed in a vacuum calcination at 900℃ for 70 min and cooled in the furnace to obtain calcined mixture C; the vacuum degree of the vacuum calcination was 30 Pa;

[0083] (4) Deionized water, bacterial solution (the microorganisms being *Thiobacillus ferrooxidans* and *Thiobacillus thiocyanate*), and sodium silicate were added to the calcination mixture C. Microbial leaching was carried out at 60°C for 9 hours, followed by standing and separation. The supernatant was removed. The microbial leaching step was repeated until the supernatant was neutral. Solid-liquid separation was performed, and the solid was dried to obtain a low-sulfur composite reducing agent. The concentration of the bacterial solution was 7.5 × 10⁻⁶. 7 The liquid-to-solid ratio of deionized water to calcined mixture C is 13:1 (mL:g); the amount of bacterial solution added is 2% of the volume of deionized water, and the amount of sodium silicate added is 6 g / L.

[0084] In this embodiment, the low-sulfur composite reducing agent has a bonding index of 50, a desulfurization rate of 92.1%, and a reaction activation energy of 16.9 KJ / mol.

[0085] Comparative Example 11: The difference between this comparative example and Example 6 is that the vacuum calcination in step (3) is not included, and deionized water, bacterial solution (the microorganisms are ferrooxidizobacterium and thiobacillus thiocyanate) and sodium silicate are directly added to mixture B for microbial leaching;

[0086] The composite reducing agent obtained in this comparative example has a bonding index of 17, a desulfurization rate of 46.8%, and a reaction activation energy of 18.3 KJ / mol.

[0087] Comparative Example 12: The difference between this comparative example and Example 6 is that: in step (4), no bacterial solution (the microbial bacteria are ferrooxidizobacterium and thiobacillus thiocyanate) and sodium silicate are added, and only deionized water is used to leach the calcined mixture C;

[0088] The composite reducing agent obtained in this comparative example has a bonding index of 13, a desulfurization rate of 39.1%, and a reaction activation energy of 19.2 KJ / mol.

[0089] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing a reducing agent for silicon smelting from non-sticky, high-sulfur bituminous coal by vacuum roasting coupled with microbial upgrading, characterized in that... The specific steps are as follows: (1) Dry blocky non-sticky high-sulfur bituminous coal and dry corn cob are crushed to obtain bituminous coal powder and corn cob powder respectively. (2) Mix the bituminous coal powder and corn cob powder evenly to obtain mixture A. Add hydrogen peroxide solution to mixture A and grind and mix evenly to obtain mixture B. (3) Mixture B is placed in a vacuum calcination at a temperature of 800-1200℃ for 30-90 min, and then cooled in the furnace to obtain calcined mixture C; (4) Add deionized water, bacterial solution and sodium silicate to the calcination mixture C, and carry out microbial leaching at a temperature of 25-65℃ for 5-10 hours. Let it stand and separate into layers, and remove the supernatant. Repeat the microbial leaching step until the supernatant is neutral, separate the solid and liquid, and dry the solid to obtain a low-sulfur composite reducing agent. The microorganisms in the bacterial solution are one or more of Thiobacillus thiooxidans, Thiobacillus thioreducans, Thiobacillus ferrooxidans and Thiobacillus denitrification.

2. The method for preparing a reducing agent for silicon smelting from vacuum roasting coupled with microbial upgrading of non-sticky high-sulfur bituminous coal according to claim 1, characterized in that: The caking index of the non-caking high-sulfur bituminous coal in step (1) is 0-7, and the total sulfur content is 3%-8%; the total alkali metal content in the corn cob powder is 10-35 wt.%, the organic acid content is 10-25 wt%, and the organic matter content is 30-55 wt%.

3. The method for preparing a reducing agent for silicon smelting from vacuum roasting coupled with microbial upgrading of non-sticky high-sulfur bituminous coal according to claim 1, characterized in that: Based on the mass of mixture A, in step (2), the bituminous coal accounts for 60-90% and the corn cob accounts for 10-40% of mixture A; the mass concentration of hydrogen peroxide solution is 3-8%, and the amount of hydrogen peroxide solution added is 4-10% of the mass of mixture A.

4. The method for preparing a reducing agent for silicon smelting from vacuum roasting coupled with microbial upgrading of non-sticky high-sulfur bituminous coal according to claim 1, characterized in that: The vacuum degree of step (3) vacuum calcination is 10. -3 Pa ~ 100 Pa.

5. The method for preparing a reducing agent for silicon smelting from vacuum roasting coupled with microbial upgrading of non-sticky high-sulfur bituminous coal according to claim 1, characterized in that: The concentration of the bacterial solution in step (4) is 1.6 × 10⁻⁶. 6 ~1.6×10 8 per mL.

6. The method for preparing a reducing agent for silicon smelting from vacuum roasting coupled with microbial upgrading of non-sticky high-sulfur bituminous coal according to claim 1, characterized in that: Step (4) The liquid-solid ratio of deionized water to calcined mixture C is 8-15:1 (mL:g); the amount of bacterial solution added is 1-3% of the volume of deionized water, and the amount of sodium silicate added is 2-6 g / L.

7. The method for preparing a reducing agent for silicon smelting from vacuum roasting coupled with microbial upgrading of non-sticky high-sulfur bituminous coal according to claim 1, characterized in that: Step (4) The low-sulfur composite reducing agent has a bonding index of 28 to 53 and a reaction activation energy of 13.4 to 17.7 KJ / mol.