Purification and activation integrated method of coal for industrial silicon smelting

Abstract

The invention relates to a purification and activation integrated method of coal for industrial silicon smelting, and belongs to the technical field of industrial silicon smelting. Aiming at the problems of product quality reduction and high production energy consumption caused by high impurity content and low reaction activity of coal for industrial silicon smelting, the method comprises the following steps: crushing reducing agent coal for industrial silicon smelting to obtain coal particles; adding the coal particles into an acidic impurity removal agent-active agent mixed solution, carrying out mechanical stirring, activating and impurity removal, and carrying out solid-liquid separation to obtain coarse purified coal particles; adding the coarsely purified coal particles into an oxidant-modifier mixed solution for oxidation modification treatment, and carrying out solid-liquid separation to obtain activated coal particles; and adding the activated coal particles into an alkaline solution for soaking treatment, carrying out solid-liquid separation, and drying the solid to obtain the reducing agent coal particles for smelting the low-impurity and high-activity industrial silicon. Synchronous purification and activation of coal for industrial silicon smelting are integrated, reaction conditions are mild, the process is simple, and production automation, mechanization and large-scale production are easy to achieve.

Description

Technical Field

[0001] The invention relates to an integrated method for purifying and activating coal for industrial silicon smelting, belonging to the technical field of industrial silicon smelting. Background Art

[0002] Industrial silicon is the basic raw material for the production of photovoltaic crystalline silicon, organic silicon, and silicon alloys. It is obtained by smelting silica and carbonaceous reducing agents in a submerged arc furnace. Among many reducing agents, charcoal has a low impurity content, high reactivity and resistivity, and is an ideal choice for reducing agents for industrial silicon smelting. However, due to ecological problems caused by the consumption of forest resources, the use of charcoal is greatly restricted. Coal, as a traditional energy source, has considerable reserves. With the large-scale application of large submerged arc furnaces, coal has a lower cost advantage in large submerged arc furnaces. The full coal process has entered commercial application, and coal has become the main reducing agent for industrial silicon smelting. Since coal is a natural fossil energy source, it is inevitable to bring in mineral impurities during the molding, mining and transportation process. Impurities will partially enter the industrial silicon product along with the carbon thermal reduction reaction in the electric furnace, which will have a significant adverse effect on the production of downstream industries and product performance. In addition, the reactivity of coal is weaker than that of charcoal, resulting in huge energy consumption in actual smelting. Therefore, it is required that the impurity content of coal used for silicon smelting is as low as possible and has a high reactivity, so as to reduce unit energy consumption and output high-quality industrial silicon. At present, industrial silicon smelting controls furnace conditions and industrial silicon impurity content by selecting high-quality coal with low impurities and high activity. With the rapid consumption of high-quality coal resources, the industry urgently needs to develop a universal coal purification and activation process for industrial silicon smelting.

[0003] The mainstream process for purifying coal for silicon smelting is physical washing (jigging method, heavy medium method). In actual application, the physical method has some disadvantages, namely, it can only remove large-particle mineral impurities, cannot effectively separate sparsely distributed small-particle impurities, and is prone to secondary impurities. Therefore, the quality of coal produced by physical washing mainly depends on the characteristics of the original coal and is not universally applicable. In addition, the existing process mainly focuses on the purification of coal. For the activation of coal for industrial silicon smelting, there is currently no industrial silicon smelting coal production process that integrates purification and activation. Summary of the invention

[0004] In view of the poor universality of existing coal purification technologies for industrial silicon smelting and the inability to simultaneously improve the reaction activity of coal, the present invention proposes an integrated method for purification and activation of coal for industrial silicon smelting, which exposes mineral impurities inside the coal through mechanical stirring and acidic activation, and strengthens the removal of impurities such as silicates, carbonates, and oxide ores to obtain crude purified coal particles; the crude purified coal particles are oxidatively modified by an oxidant-modifier solution to deeply remove sulfide ores and organic impurities, and at the same time, the swelling of the crude purified coal particles is regulated to strengthen the porous structure, the modifier replaces hydrogen atoms and is grafted onto the coal particles, the oxidant reacts with the coal to form oxygen-containing functional groups such as aldehydes, carboxylic acids, and hydroxyls, and the two together provide oxygen-containing active sites to obtain activated coal particles; the activated coal particles are subjected to alkali treatment to remove titanium impurities, and alkali metal ions replace atoms on the oxygen-containing active sites and connect with them, so as to obtain low-impurity and high-activity coal suitable for industrial silicon smelting.

[0005] An integrated method for purifying and activating coal for industrial silicon smelting, the specific steps are as follows:

[0006] (1) crushing the reducing agent coal used for industrial silicon smelting to obtain coal particles;

[0007] (2) adding coal particles into an acidic impurity remover-activator mixed solution for mechanical stirring to activate and remove impurities, and performing solid-liquid separation to obtain crude purified coal particles; preferably, the crude purified coal particles have a particle size of 0.5 to 1.5 cm;

[0008] (3) The crude purified coal particles (containing sulfide and organic impurities) are added to an oxidant-modifier mixed solution for oxidation modification, and the solid-liquid separation is performed to obtain activated coal particles; under the action of the oxidant, the sulfide and organic impurities are removed as free ions, and oxygen-containing active sites are formed on the surface of the coal particles, thereby improving the reaction activity of the coal; the modifier can coordinate with the impurity ions to form a chelate, thereby enhancing the impurity removal effect, and at the same time, the modifier can be grafted onto the coal particles to increase the oxygen-containing active sites and provide chemical conditions for coal swelling;

[0009] (4) The activated coal particles are added to an alkaline solution for soaking treatment, solid-liquid separation, and solid drying to obtain low-impurity and high-activity industrial silicon smelting reducing agent coal particles. Alkali treatment removes titanium oxide and ilmenite into soluble titanates, and alkali metals replace hydrogen atoms on oxygen-containing functional groups in coal, further improving the reaction activity of coal; the soaking process can be left standing without stirring, and the soaking time should not be too long to avoid causing a decrease in the mechanical properties of the coal particles.

[0010] Preferably, the particle size of the coal particles in step (1) is 2 to 3 cm, the total amount of metal impurities in the coal particles is 0.8 to 8 wt.%, and the total amount of non-metallic impurities is 0.5 to 1.5 wt.%.

[0011] The metal impurity elements in step (1) include one or more of iron, aluminum, calcium, and titanium, and the non-metallic impurity elements include one or more of boron, phosphorus, and sulfur.

[0012] Impurities in the coal particles include, but are not limited to, silicates, oxide minerals, carbonates, sulfates, phosphates, and borates.

[0013] Preferably, the acidic impurity remover in the acidic impurity remover-active agent mixed solution in step (2) is two or more of hydrochloric acid, sulfuric acid, and hydrofluoric acid, the active agent is sodium lignin sulfonate, polyethylene glycol, or sodium polyacrylate, and the mass concentration of the acidic impurity remover in the acidic impurity remover-active agent mixed solution is 10-30%, and the mass concentration of the active agent is 0.1-0.5%.

[0014] Preferably, the liquid-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles in step (2) is 2 to 10:1 in mL:g, the mechanical stirring rate is 2 to 10 rpm, and the activation impurity removal time is 0.5 to 2 hours. Under the action of mechanical force (stirring rate is 2 to 10 rpm), a large number of cracks and pores are generated on the surface of the coal, so that the internal impurities are fully in contact with the impurity remover, which can reduce the activation energy required for the reaction between the impurities and the impurity remover; too fast a rotation speed or too long a time will increase energy consumption and cause the coal particles to be too fine to meet the requirements of industrial silicon production.

[0015] Preferably, in the oxidant-modifier mixed solution of step (3), the mass concentration of the oxidant is 3-15%, and the mass concentration of the modifier is 10-15%.

[0016] Preferably, the oxidant in step (3) is one or more of hydrogen peroxide, sodium hypochlorite, ferric sulfate, ferric chloride, sodium peroxide, peracetic acid, sodium percarbonate, and sodium persulfate, and the modifier is one or more of oxalic acid, citric acid, ethanol, propanol, and cyclohexanol.

[0017] Preferably, the liquid-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles in step (3) is 1 to 2:1, the oxidation modification treatment temperature is 15 to 70°C, and the time is 4 to 8 hours. The oxidation modification process is left to stand without stirring. The purpose of long-term immersion is to make the coal particles swell and form a loose porous structure on the surface.

[0018] Preferably, the alkaline solution in step (4) is one or more of sodium hydroxide, potassium hydroxide, sodium chloride, potassium chloride, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate, and the mass concentration of the alkaline solution is 5-15%.

[0019] Preferably, the liquid-to-solid ratio of the alkaline solution to the activated coal particles is 1 to 1.5:1 in mL:g, the soaking treatment temperature is 15 to 50°C, and the time is 0.5 to 2 hours.

[0020] Preferably, the impurity content of the reducing agent coal particles for low-impurity and high-activity industrial silicon smelting in step (4) is: iron <0.1wt.%, aluminum <0.2wt.%, calcium <0.2wt.%, titanium <0.01wt.%, boron <0.005wt.%, phosphorus <0.001wt.%, and sulfur <0.3wt.%.

[0021] Preferably, the reaction activity of the low-impurity and high-activity reducing agent coal particles for industrial silicon smelting in step (4) is increased by 10 to 25%.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention adopts acidic mechanical activation to increase the pores and defects of coal particles under the action of mechanical stress and chemical corrosion, reduce the reaction activation energy, fully expose the internal impurity minerals, and create more contact points between impurities and impurity removers; compared with the traditional crushing and impurity removal process, efficient impurity removal-activation is achieved in one step;

[0024] (2) The present invention uses oxidants and modifiers to strengthen the removal of sulfide ores and organic impurities, and simultaneously increases the number of oxygen-containing functional groups in coal particles, providing cross-linking active sites for alkali treatment; alkali treatment can remove titanium impurities, and alkali metals are loaded to improve reaction activity, thereby achieving simultaneous purification and activation;

[0025] (3) The present invention integrates an efficient purification and activation integrated process, has mild reaction conditions, simple process, strong universality, and has the advantages of easy realization of production automation, mechanization and scale, and can produce industrial silicon smelting coal with low iron, low aluminum, low calcium, low titanium, low sulfur, low phosphorus and low boron, and improve the reaction activity by 10 to 25% based on the raw coal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is the coal gasification reaction activity curve of Example 1 and Comparative Example 1;

[0027] Figure 2 2 are the coal gasification reaction activity curves of Example 2 and Comparative Example 2;

[0028] Figure 3 3 are the coal gasification reaction activity curves of Example 3 and Comparative Example 3;

[0029] Figure 4 1 is the coal gasification reaction activity curve of Example 4 and Comparative Example 4;

[0030] Figure 5 2 are the coal gasification reaction activity curves of Example 5 and Comparative Example 5. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0032] In the embodiments of the present invention, the impurity content in the coal is determined by pretreatment according to GB / T 30732-2014 and analysis by ICP-OES; the chemical reactivity of the coal is determined according to GB / T 220-2018, the chemical reactivity of coal to carbon dioxide.

[0033] Example 1: The impurity contents of the reducing agent coal for industrial silicon smelting in this example are 1.88wt.% iron, 4.15wt.% aluminum, 0.83wt.% calcium, 0.17wt.% titanium, 0.073wt.% boron, 0.036wt.% phosphorus, and 0.36wt.% sulfur;

[0034] An integrated method for purifying and activating coal for industrial silicon smelting, the specific steps are as follows:

[0035] (1) crushing the reducing agent coal for industrial silicon smelting to a particle size of 2 to 3 cm to obtain coal particles;

[0036] (2) adding coal particles to an acidic impurity remover-activator mixed solution, mechanically stirring and activating the impurities for 2 hours at a stirring rate of 5 rpm, and performing solid-liquid separation to obtain crude purified coal particles with a particle size of 0.5 to 1.5 cm; the acidic impurity remover-activator mixed solution contains 5 wt.% hydrochloric acid, 5 wt.% hydrofluoric acid, and 0.1 wt.% activator (sodium lignin sulfonate), and the liquid-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles is 4:1 in mL:g;

[0037] (3) adding crude purified coal particles (containing sulfide and organic impurities) to an oxidant-modifier mixed solution, oxidizing and modifying the mixture at 15°C without stirring for 8 hours, and obtaining activated coal particles by solid-liquid separation; the oxidant-modifier mixed solution contains 15wt.% ethanol modifier and 3wt.% hydrogen peroxide oxidizing agent, and the liquid-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles is 1.5:1 in mL:g;

[0038] (4) The activated coal particles are added to an alkaline solution (15 wt.% sodium hydroxide), immersed at a temperature of 25° C. for 1 hour, and the solid-liquid separation is performed. The solid is dried to obtain a reducing agent coal particle for industrial silicon smelting with low impurities and high activity; the liquid-solid ratio of the alkaline solution (15 wt.% sodium hydroxide) to the activated coal particles is 1.5:1 in mL:g;

[0039] After testing, the impurity contents of the low-impurity and high-activity reducing agent coal particles for industrial silicon smelting in this embodiment are 0.083wt.% iron, 0.15wt.% aluminum, 0.18wt.% calcium, 0.0061wt.% titanium, 0.0024wt.% boron, 0.00071wt.% phosphorus, and 0.11wt.% sulfur; the untreated coal is comparative example 1, and the gasification reaction activity of the comparative example 1 coal with carbon dioxide at 1200°C is 88.06%, while the gasification reaction activity of the low-impurity and high-activity coal in this embodiment is 100% at 1200°C, and the gasification reaction activity is increased by 11.94%.

[0040] Example 2: The impurity contents of the reducing agent coal for industrial silicon smelting in this example are 1.37wt.% iron, 5.63wt.% aluminum, 0.42wt.% calcium, 0.11wt.% titanium, 0.046wt.% boron, 0.027wt.% phosphorus, and 0.47wt.% sulfur;

[0041] An integrated method for purifying and activating coal for industrial silicon smelting, the specific steps are as follows:

[0042] (1) crushing the reducing agent coal for industrial silicon smelting into a particle size of 2 to 3 cm to obtain coal particles;

[0043] (2) adding coal particles to an acidic impurity remover-activator mixed solution, mechanically stirring and activating impurities for 1.5 hours at a stirring rate of 7 rpm, and performing solid-liquid separation to obtain crude purified coal particles with a particle size of 0.5 to 1.5 cm; the acidic impurity remover-activator mixed solution contains 20 wt.% sulfuric acid, 8 wt.% hydrofluoric acid, and 0.2 wt.% activator (polyethylene glycol), and the liquid-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles is 2:1 in mL:g;

[0044] (3) adding crude purified coal particles (containing sulfide and organic impurities) to an oxidant-modifier mixed solution, oxidizing and modifying the mixture at 50°C without stirring for 5 hours, and obtaining activated coal particles by solid-liquid separation; the oxidant-modifier mixed solution contains 10wt.% citric acid modifier and 5wt.% sodium persulfate oxidant, and the liquid-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles is 3:1 in mL:g;

[0045] (4) adding the activated coal particles into an alkaline solution (5 wt.% potassium carbonate), soaking them at 30°C for 1.5 hours, separating the solid and the liquid, and drying the solid to obtain the reducing agent coal particles for industrial silicon smelting with low impurities and high activity; the liquid-solid ratio of the alkaline solution (5 wt.% potassium carbonate) to the activated coal particles is 1:1 in mL:g;

[0046] After testing, the impurity contents of the low-impurity and high-activity reducing agent coal particles for industrial silicon smelting in this embodiment are 0.056wt.% iron, 0.18wt.% aluminum, 0.010wt.% calcium, 0.0073wt.% titanium, 0.0025wt.% boron, 0.00076wt.% phosphorus, and 0.18wt.% sulfur; the untreated coal is Comparative Example 2, and the gasification reaction activity of the Comparative Example 2 coal with carbon dioxide at 1200°C is 83.82%, while the gasification reaction activity of the low-impurity and high-activity coal in this embodiment is 100% at 1200°C, and the gasification reaction activity is increased by 16.18%.

[0047] Example 3: The impurity contents of the reducing agent coal for industrial silicon smelting in this example are 2.01wt.% iron, 1.98wt.% aluminum, 0.10wt.% calcium, 0.18wt.% titanium, 0.080wt.% boron, 0.015wt.% phosphorus, and 1.08wt.% sulfur;

[0048] An integrated method for purifying and activating coal for industrial silicon smelting, the specific steps are as follows:

[0049] (1) crushing the reducing agent coal for industrial silicon smelting to a particle size of 2 to 3 cm to obtain coal particles;

[0050] (2) adding coal particles to an acidic impurity remover-activator mixed solution, mechanically stirring and activating the impurities for 2 hours at a stirring rate of 3 rpm, and performing solid-liquid separation to obtain crude purified coal particles with a particle size of 0.5 to 1.5 cm; the acidic impurity remover-activator mixed solution contains 15 wt.% sulfuric acid, 5 wt.% hydrofluoric acid, and 0.3 wt.% activator (sodium polyacrylate), and the liquid-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles is 3:1 in mL:g;

[0051] (3) adding crude purified coal particles (containing sulfide and organic impurities) to an oxidant-modifier mixed solution, oxidizing and modifying the mixture at 30°C without stirring for 6 hours, and obtaining activated coal particles by solid-liquid separation; the oxidant-modifier mixed solution contains 15wt.% oxalic acid modifier and 10wt.% peracetic acid oxidant, and the liquid-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles is 2:1 in mL:g;

[0052] (4) The activated coal particles are added to an alkaline solution (15 wt.% potassium hydroxide), immersed at a temperature of 30° C. for 1.2 h, and the solid-liquid separation is performed, and the solid is dried to obtain a reducing agent coal particle for industrial silicon smelting with low impurities and high activity; the liquid-solid ratio of the alkaline solution (15 wt.% sodium hydroxide) to the activated coal particles is 1:1 in mL:g;

[0053] After testing, the impurity contents of the low-impurity and high-activity reducing agent coal particles for industrial silicon smelting in this embodiment are 0.049wt.% iron, 0.16wt.% aluminum, 0.0020wt.% calcium, 0.0038wt.% titanium, 0.0035wt.% boron, 0.00049wt.% phosphorus, and 0.13wt.% sulfur; the untreated coal is comparative example 3, and the gasification reaction activity of the comparative example 3 coal with carbon dioxide at 1300°C is 78.48%, while the gasification reaction activity of the low-impurity and high-activity coal in this embodiment is 100% at 1300°C, and the gasification reaction activity is increased by 21.52%.

[0054] Example 4: The impurity contents of the reducing agent coal for industrial silicon smelting in this example are 1.85wt.% iron, 0.54wt.% aluminum, 1.67wt.% calcium, 0.098wt.% titanium, 0.074wt.% boron, 0.013wt.% phosphorus, and 2.17wt.% sulfur;

[0055] An integrated method for purifying and activating coal for industrial silicon smelting, the specific steps are as follows:

[0056] (1) crushing the reducing agent coal for industrial silicon smelting to a particle size of 2 to 3 cm to obtain coal particles;

[0057] (2) adding coal particles to an acidic impurity remover-activator mixed solution, mechanically stirring at a stirring rate of 10 rpm for activation and impurity removal for 1 hour, and performing solid-liquid separation to obtain crude purified coal particles with a particle size of 0.5 to 1.5 cm; the acidic impurity remover-activator mixed solution contains 15 wt.% hydrochloric acid, 10 wt.% sulfuric acid, and 0.5 wt.% activator (sodium lignin sulfonate), and the liquid-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles is 7:1 in mL:g;

[0058] (3) adding crude purified coal particles (containing sulfide and organic impurities) to an oxidant-modifier mixed solution, oxidizing and modifying the mixture at 70° C. without stirring for 4 h, and performing solid-liquid separation to obtain activated coal particles; the oxidant-modifier mixed solution contains 12 wt.% propanol modifier and 15 wt.% sodium hypochlorite oxidant, and the liquid-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles is 1:1 in mL:g;

[0059] (4) The activated coal particles are added to an alkaline solution (5wt.% sodium chloride and 5% sodium hydroxide), immersed at a temperature of 50°C for 2h, solid-liquid separation, and solid drying to obtain low-impurity and high-activity reducing agent coal particles for industrial silicon smelting; the liquid-solid ratio of the alkaline solution (5wt.% sodium chloride and 5% sodium hydroxide) to the activated coal particles is 1.5:1 in mL:g;

[0060] After testing, the impurity contents of the low-impurity and high-activity reducing agent coal particles for industrial silicon smelting in this embodiment are 0.052wt.% iron, 0.17wt.% aluminum, 0.081wt.% calcium, 0.0076wt.% titanium, 0.0021wt.% boron, 0.00066wt.% phosphorus, and 0.097wt.% sulfur; the untreated coal is Comparative Example 4, and the gasification reaction activity of the Comparative Example 4 coal with carbon dioxide at 1300°C is 75.64%, while the gasification reaction activity of the low-impurity and high-activity coal in this embodiment is 100% at 1300°C, and the gasification reaction activity is increased by 24.36%.

[0061] Example 5: The impurity contents of the reducing agent coal for industrial silicon smelting in this example are 0.64wt.% iron, 5.16wt.% aluminum, 0.49wt.% calcium, 0.11wt.% titanium, 0.095wt.% boron, 0.0086wt.% phosphorus, and 0.73wt.% sulfur;

[0062] An integrated method for purifying and activating coal for industrial silicon smelting, the specific steps are as follows:

[0063] (1) crushing the reducing agent coal for industrial silicon smelting to a particle size of 2 to 3 cm to obtain coal particles;

[0064] (2) adding coal particles to an acidic impurity remover-activator mixed solution, mechanically stirring and activating impurities for 2 hours at a stirring rate of 2 rpm, and performing solid-liquid separation to obtain crude purified coal particles with a particle size of 0.5 to 1.5 cm; the acidic impurity remover-activator mixed solution contains 20 wt.% hydrochloric acid, 10 wt.% hydrofluoric acid, and 0.4 wt.% activator (polyethylene glycol), and the liquid-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles is 10:1 in mL:g;

[0065] (3) adding crude purified coal particles (containing sulfide and organic impurities) to an oxidant-modifier mixed solution, oxidizing and modifying the mixture at 60° C. without stirring for 7 h, and obtaining activated coal particles by solid-liquid separation; the oxidant-modifier mixed solution contains 10 wt.% cyclohexanol modifier and 7 wt.% sodium percarbonate oxidant, and the liquid-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles is 1.5:1 in mL:g;

[0066] (4) The activated coal particles are added to an alkaline solution (5wt.% potassium chloride and 10% sodium bicarbonate), soaked at a temperature of 15°C for 0.5h, solid-liquid separation, and solid drying to obtain low-impurity and high-activity reducing agent coal particles for industrial silicon smelting; the liquid-solid ratio of the alkaline solution (5wt.% potassium chloride and 10% sodium bicarbonate) to the activated coal particles is 1.2:1 in mL:g;

[0067] After testing, the impurity content of the low-impurity high-activity industrial silicon smelting reducing agent coal particles in this embodiment is 0.063wt.% iron, 0.094wt.% aluminum, 0.076wt.% calcium, 0.0021wt.% titanium, 0.0039wt.% boron, 0.00058wt.% phosphorus, and 0.21wt.% sulfur; the untreated coal is comparative example 5, and the gasification reaction activity of the comparative example 5 coal with carbon dioxide at 1300°C is 72.97%, while the gasification reaction activity of the low-impurity high-activity coal in this embodiment is 91.54% at 1300°C, and the gasification reaction activity is increased by 18.57%. The above is a detailed description of the specific embodiments of the present invention, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. An integrated method for purifying and activating coal for industrial silicon smelting, characterized in that: The specific steps are as follows: (1) crushing the reducing agent coal used for industrial silicon smelting to obtain coal particles; (2) adding coal particles into an acidic impurity remover-activator mixed solution for mechanical stirring to activate and remove impurities, and performing solid-liquid separation to obtain crude purified coal particles; (3) adding the crude purified coal particles into an oxidant-modifier mixed solution for oxidation modification, and performing solid-liquid separation to obtain activated coal particles; (4) The activated coal particles are added to an alkaline solution for soaking, solid-liquid separation, and solid drying to obtain reducing agent coal particles with low impurities and high activity for industrial silicon smelting.

2. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1, characterized in that: The particle size of the coal particles in step (1) is 2 to 3 cm, the total amount of metal impurities in the coal particles is 0.8 to 8 wt.%, and the total amount of non-metallic impurities is 0.5 to 1.5 wt.%.

3. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 2, characterized in that: The metal impurity elements in step (1) include one or more of iron, aluminum, calcium, and titanium, and the non-metal impurity elements include one or more of boron, phosphorus, and sulfur.

4. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1, characterized in that: The acidic impurity remover in the acidic impurity remover-activator mixed solution of step (2) is two or more of hydrochloric acid, sulfuric acid and hydrofluoric acid, the activator is sodium lignin sulfonate, polyethylene glycol or sodium polyacrylate, the mass concentration of the acidic impurity remover in the acidic impurity remover-activator mixed solution is 10-30%, and the mass concentration of the activator is 0.1-0.5%.

5. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1 or 4, characterized in that: In step (2), the liquid-to-solid ratio of the acidic impurity remover-activator mixed solution to the coal particles is 2 to 10:1 in mL:g, the mechanical stirring rate is 2 to 10 rpm, and the activation impurity removal time is 0.5 to 2 h.

6. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1, characterized in that: In step (3), the mass concentration of the oxidant in the oxidant-modifier mixed solution is 3-15%, and the mass concentration of the modifier is 10-15%.

7. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1 or 6, characterized in that: In step (3), the oxidant is one or more of hydrogen peroxide, sodium hypochlorite, ferric sulfate, ferric chloride, sodium peroxide, peracetic acid, sodium percarbonate, and sodium persulfate, and the modifier is one or more of oxalic acid, citric acid, ethanol, propanol, and cyclohexanol.

8. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1 or 6, characterized in that: In step (3), the liquid-to-solid ratio of the oxidant-modifier mixed solution to the crude purified coal particles is 1 to 2:1 in mL:g, the oxidation modification treatment temperature is 15 to 70°C, and the time is 4 to 8 hours.

9. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1, characterized in that: The alkaline solution in step (4) is one or more of sodium hydroxide, potassium hydroxide, sodium chloride, potassium chloride, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate, and the mass concentration of the alkaline solution is 5-15%.

10. The integrated method for purifying and activating coal for industrial silicon smelting according to claim 1 or 9, characterized in that: The liquid-solid ratio of the alkaline solution to the activated coal particles is 1 to 1.5:1 in mL:g, the soaking treatment temperature is 15 to 50°C, and the time is 0.5 to 2h.

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