A method for purifying a reducing agent coal for industrial silicon production

Abstract

This invention discloses a method for purifying reducing agent coal used in industrial silicon production, belonging to the field of chemical raw material purification technology. The invention provides a purifying agent that enters the interior of the reducing agent coal through the pores to carry out an iron removal reaction. Nonylphenol polyoxyethylene ether promotes the dissolution of oxalic acid in water and inhibits foam formation. Iron in reducing agent coal used in industrial silicon production mainly exists in two modes: Fe2O3 accounts for 40%-50%, and FeS accounts for 50%-60%. Since Fe2O3 can react with oxalic acid (H2C2O4) to form a precipitate that is insoluble in water, washing with water after soaking achieves the purpose of iron removal. The method of purifying reducing agent coal used in industrial silicon production using a purifying agent can significantly remove trace impurities such as Fe, Al, and Ca that affect the quality of industrial silicon products.

Description

Technical Field

[0001] This invention belongs to the field of chemical raw material purification technology, specifically relating to a method for purifying coal, a reducing agent used in industrial silicon production. Background Technology

[0002] Currently, in industrial silicon production, the quality of raw materials determines the quality of the product because Fe is inherently non-removable during the process. Furthermore, the reducing agent coal used in the reduction reaction undergoes only a simple water washing process, which cannot improve the quality of the industrial silicon product.

[0003] Existing water washing technology can only reduce the ash content on the surface of reducing agent coal, but cannot effectively remove impurities inside the reducing agent coal such as Fe, Al, and Ca. Summary of the Invention

[0004] The purpose of this invention is to provide a method for purifying coal, a reducing agent used in industrial silicon production. This purification method can significantly remove trace impurity elements Fe, Al, and Ca that affect the quality of industrial silicon products.

[0005] This invention is achieved through the following technical solution:

[0006] A method for purifying coal as a reducing agent in industrial silicon production, comprising:

[0007] Select the purifying agent according to the corresponding mass fraction, add it to the reducing agent coal, mix and soak and wash with water to obtain the purified reducing agent coal.

[0008] Preferably, the purifying agent is obtained by mixing oxalic acid, nonylphenol polyoxyethylene ether, and water.

[0009] Preferably, the purifying agent contains 10 wt% oxalic acid, 89 wt% nonylphenol polyoxyethylene ether, and 1 wt% water.

[0010] Since the solubility of oxalic acid at room temperature (26℃) is approximately 12.5%, a 10% oxalic acid concentration is selected to ensure complete dissolution. Nonylphenol polyoxyethylene ether can achieve its own promoting effect at a concentration of 1%, and excessive application would increase production costs.

[0011] Preferably, the purifying agent contains 12 wt% oxalic acid, 87 wt% nonylphenol polyoxyethylene ether, and 2 wt% water.

[0012] The above invention provides a purification agent made from a mixture of oxalic acid, nonylphenol polyoxyethylene ether, and water. This purification agent enters the interior of the reducing coal through the pores to carry out an iron removal reaction. The nonylphenol polyoxyethylene ether promotes the dissolution of oxalic acid in water and inhibits foam formation. The iron in the reducing coal used in industrial silicon production exists primarily in two modes: Fe2O3 and FeS, with Fe2O3 accounting for 40%-50% and FeS accounting for 50%-60%. Oxalic acid is used because Fe2O3 reacts with oxalic acid (H2C2O4) as follows: Fe2O3 + H2C2O4 = Fe2(C2O4)3 + H2O. The product Fe2(C2O4)3 is a precipitate, insoluble in water. After soaking, rinsing with water achieves the purpose of iron removal.

[0013] Preferably, the soaking temperature is 25-30℃.

[0014] Preferably, the soaking time is 65-72 hours.

[0015] The soaking temperature is limited to 25-30℃ to ensure the solubility of oxalic acid. Only when the soaking time is greater than 65 hours can the oxalic acid react fully with the ferric oxide in the reducing agent coal, thereby maximizing the iron removal rate.

[0016] If the temperature is below the aforementioned limit, oxalic acid cannot dissolve completely; if it is above the limit, specialized heating equipment is required, increasing production costs. When the ambient temperature is below 25°C, an electric heating tape can be used to achieve the required temperature, minimizing production costs. If the soaking time is less than 65 hours, oxalic acid cannot react fully with the ferric oxide in the reducing agent coal, reducing the iron removal rate. If the soaking time is greater than 72 hours, the average yield per unit time decreases, reducing enterprise profits.

[0017] Preferably, the mass ratio of the purifying agent to the reducing agent coal is 1:1.

[0018] Preferably, the pipe inner diameter is 1.5cm, the water pressure is 0.5-0.6MP, the flow rate is 32L / S, and the washing time is 1-1.5min.

[0019] A method for purifying reducing agent coal used in industrial silicon production yields purified reducing agent coal.

[0020] Compared with the prior art, the present invention has at least the following technical effects:

[0021] This invention provides a purification agent made from a mixture of oxalic acid, nonylphenol polyoxyethylene ether, and water. This purification agent enters the interior of the reducing coal through the pores to carry out an iron removal reaction. The nonylphenol polyoxyethylene ether promotes the dissolution of oxalic acid in water and inhibits foam formation. The iron in the reducing coal used in industrial silicon production exists primarily in two modes: Fe2O3 and FeS, with Fe2O3 accounting for 40%-50% and FeS accounting for 50%-60%. Oxalic acid is used because Fe2O3 reacts with oxalic acid (H2C2O4) as follows: Fe2O3 + H2C2O4 = Fe2(C2O4)3 + H2O. The resulting Fe2(C2O4)3 is a precipitate, insoluble in water. After soaking, rinsing with water achieves the purpose of iron removal.

[0022] This invention provides a method for purifying reducing agent coal used in industrial silicon production using a purifying agent. The method involves soaking the reducing agent coal with a purifying agent and then washing it with water, which significantly removes trace impurity elements Fe, Al, and Ca that affect the quality of industrial silicon products. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions not specified in the examples shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] One specific embodiment of the present invention is as follows:

[0025] A method for purifying coal as a reducing agent in industrial silicon production, comprising:

[0026] Select the purifying agent according to the corresponding mass fraction, add it to the reducing agent coal, mix and soak and wash with water to obtain the purified reducing agent coal.

[0027] Preferably, the purifying agent is obtained by mixing oxalic acid, nonylphenol polyoxyethylene ether, and water.

[0028] Preferably, the purifying agent contains 10 wt% oxalic acid, 89 wt% nonylphenol polyoxyethylene ether, and 1 wt% water.

[0029] Preferably, the purifying agent contains 12 wt% oxalic acid, 87 wt% nonylphenol polyoxyethylene ether, and 2 wt% water.

[0030] Preferably, the soaking temperature is 25-30℃.

[0031] Preferably, the soaking time is 65-72 hours.

[0032] Preferably, the mass ratio of the purifying agent to the reducing agent coal is 1:1.

[0033] Preferably, the pipe inner diameter is 1.5cm, the water pressure is 0.5-0.6MP, the flow rate is 32L / S, and the washing time is 1-1.5min.

[0034] A method for purifying reducing agent coal used in industrial silicon production yields purified reducing agent coal.

[0035] Example 1:

[0036] A method for purifying coal as a reducing agent in industrial silicon production, comprising:

[0037] Select the purifying agent according to the corresponding mass fraction, add it to the reducing agent coal, mix and soak and wash with water to obtain the purified reducing agent coal.

[0038] The above-mentioned purifying agent contains 10 wt% oxalic acid, 89 wt% nonylphenol polyoxyethylene ether, and 1 wt% water.

[0039] The soaking temperature mentioned above is 25℃.

[0040] The soaking time is 65 hours.

[0041] During the above water washing process, the pipe inner diameter is 1.5cm, the water pressure is 0.5-0.6MP, the flow rate is 32L / S, and the washing time is 1min.

[0042] Example 2:

[0043] A method for purifying coal as a reducing agent in industrial silicon production, comprising:

[0044] Select the purifying agent according to the corresponding mass fraction, add it to the reducing agent coal, mix and soak and wash with water to obtain the purified reducing agent coal.

[0045] The above-mentioned purifying agent contains 12 wt% oxalic acid, 87 wt% nonylphenol polyoxyethylene ether, and 2 wt% water.

[0046] The soaking temperature is 25-30℃.

[0047] The soaking time is 65-72 hours.

[0048] During the above water washing process, the pipe inner diameter is 1.5cm, the water pressure is 0.5-0.6MP, the flow rate is 32L / S, and the washing time is 1min.

[0049] Experimental Example

[0050] Experimental method: The reducing agent (coal) was divided into two groups: a control group without the purification agent and an experimental group using the purification agent prepared in Example 1. The experimental results are shown in the table below.

[0051] Result 1:

[0052]

[0053] Result 2:

[0054]

[0055] Result 3:

[0056]

[0057] Result 4:

[0058]

[0059] Conclusion: The results of the above experimental examples show that the length of soaking time affects the removal effect.

[0060] The reducing agent (coal) selected above for No. 4 material yard refers to the production coal that was purchased but was put aside due to excessive iron content (≥0.16%), and was used as a test sample again.

[0061] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for purifying coal as a reducing agent in industrial silicon production, characterized in that, include: Select the purifying agent according to the corresponding mass fraction, add it to the reducing agent coal, mix and soak and wash with water to obtain the purified reducing agent coal; The purifying agent is obtained by mixing oxalic acid, nonylphenol polyoxyethylene ether and water; The purifying agent contains 10 wt% oxalic acid, 89 wt% nonylphenol polyoxyethylene ether, and 1 wt% water. The soaking temperature is 25-30℃; The soaking time is 65-72 hours; The mass ratio of the purifying agent to the reducing agent coal is 1:1; The water washing process involves a pipe inner diameter of 1.5cm, a water pressure of 0.5-0.6MP, a flow rate of 32L / S, and a washing duration of 1-1.5min.

2. A method for purifying reducing agent coal for industrial silicon production as described in claim 1, resulting in purified reducing agent coal.

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