Method for deep dearsenication of a crude antimony chloride solution

Abstract

The application discloses a method for deep dearsenication of a crude antimony chloride solution. The method comprises the following steps: determining the mass ratio of arsenic to antimony in the crude antimony chloride solution and grading; adding a dearsenication agent to the graded crude antimony chloride solution to perform a dearsenication reaction, then performing liquid-solid separation to obtain a liquid phase and a solid phase; and performing arsenic content determination and correction on the obtained liquid phase. The method can accurately grade the mass ratio of arsenic to antimony in the crude antimony chloride solution, determine the adding amount of the dearsenication agent according to the mass ratio of arsenic to antimony, convert soluble arsenic salts into insoluble substances, and precipitate the insoluble substances. The method can realize deep dearsenication of the crude antimony chloride solution by using only a single dearsenication agent. Through detection, the arsenic content in the dearsenicated antimony chloride solution is less than 40 mg / L, and the removal rate of arsenic reaches more than 99%.

Description

Technical Field

[0001] The invention relates to a method for removing arsenic from an arsenic-containing solution, in particular to a method for deep removing arsenic from a crude antimony chloride solution, and belongs to the technical field of solution impurity removal. Background Art

[0002] During the chloride leaching process for producing antimony oxide, the crude antimony chloride solution obtained from the chloride leaching of antimony concentrate contains high arsenic levels. Without specialized arsenic removal, the product, when hydrolyzed, can easily exceed the 40 ppm arsenic standard, failing to meet purity requirements and becoming waste. A common arsenic removal method involves adding a sulfide agent to the crude antimony chloride solution to form an arsenic sulfide precipitate to remove the arsenic. However, this method is generally ineffective, requiring multiple dearsenicization reactions. Furthermore, this method is ineffective for deep arsenic removal, and poorly controlled dearsenic removal can easily result in excessive arsenic levels in the product antimony oxide. Summary of the Invention

[0003] To address the problems of the prior art, the present invention provides a method for deep arsenic removal from a crude antimony chloride solution. This method achieves deep arsenic removal from the crude antimony chloride solution by strictly grading the arsenic-antimony mass ratio in the solution, determining the amplification factor of a dearsenicizing agent, and adding a corresponding amount of the agent. This method converts soluble arsenic salts into insoluble or sparingly soluble arsenic compounds and elemental arsenic.

[0004] To achieve the above technical objectives, the present invention provides a method for deep arsenic removal from a crude antimony chloride solution, which is characterized by comprising: determining the arsenic-antimony mass ratio in the crude antimony chloride solution and classifying it according to the arsenic-antimony mass ratio; adding a dearsenicizing agent to the classified crude antimony chloride solution to carry out a dearsenicization reaction, and then performing liquid-solid separation to obtain a liquid phase and a solid phase; and determining and correcting the arsenic content in the obtained liquid phase;

[0005] The arsenic removal agent is phosphite or hypophosphite; and the amount of the arsenic removal agent added is in a linear negative correlation with the arsenic-antimony ratio in the crude antimony chloride solution.

[0006] The removal method provided by the present invention is based on the synergistic effect between the various steps. By accurately grading the arsenic-antimony mass ratio in crude antimony chloride and determining the amount of arsenic removal agent added according to the arsenic-antimony mass ratio, soluble arsenic salts are converted into insoluble substances, which are precipitated and precipitated, thereby achieving deep arsenic removal from the crude antimony chloride solution. Since the conversion reaction of the soluble arsenic salt is a reversible reaction and the acidity of the solution system is increased during the conversion process, thereby causing the precipitated arsenide to dissolve again, the amount of arsenic removal agent added needs to be strictly controlled according to the arsenic-antimony mass ratio.

[0007] As a preferred solution, the crude antimony chloride solution is divided into 6 grades according to the arsenic-antimony mass ratio As / Sb, which are as follows from small to large: As / Sb<0.00045, 0.00045≤As / Sb<0.0010, 0.0010≤As / Sb<0.0020, 0.0020≤As / Sb<0.0050, 0.0050≤As / Sb≤0.0101, and 0.0101<As / Sb.

[0008] As a preferred solution, the amount of the arsenic removal agent added is corrected according to the mass ratio of arsenic to antimony, and the addition amount is calculated as follows:

[0009] Formula 1: Dearsenicizing agent addition amount = 0.881 × A × V × C p ;

[0010] In formula 1, A is the amplification factor, which is dimensionless and ranges from 1.2 to 2.5; V is the volume of the crude antimony chloride solution, which is in L; and Cp is the arsenic content in the crude antimony chloride solution, which is in g / L.

[0011] As a preferred solution, the corresponding amounts of the amplification factor A and the mass ratio of arsenic and antimony are graded from small to large as follows: 3, 2.5, 2, 1.5, 1.35 and 1.2.

[0012] The amount of arsenic removal agent added must be precisely adjusted according to the mass ratio of arsenic to antimony. When the mass of arsenic and antimony in the solution is relatively small, the amplification factor of the amount of arsenic removal agent added is larger. This is because the arsenic content in the solution is low and difficult to convert and precipitate. By increasing the content of arsenic removal agent, the arsenic removal reaction is promoted to move in the forward direction, thereby removing trace soluble arsenic salts in the solution; when the mass of arsenic and antimony in the solution is relatively large, the arsenic content in the solution is higher. Under the premise of ensuring that the arsenic removal reaction proceeds in the forward direction, in order to prevent the occurrence of side reactions, a smaller amplification factor is selected to prevent the precipitated arsenic compound from dissolving again, thereby achieving deep arsenic removal of the solution.

[0013] As a preferred solution, the arsenic removal reaction process is: adding the arsenic removal agent at 100-110° C. and stirring the reaction for 1.5-2.5 hours, and then allowing the reaction to settle for 10-14 hours after the reaction is completed.

[0014] As a preferred solution, the arsenic content correction process is: when the arsenic content in the obtained liquid phase is greater than 40 mg / L, the arsenic removal reaction is continued until the arsenic content in the liquid phase is less than or equal to 40 mg / L.

[0015] As a preferred solution, the antimony content in the crude antimony chloride solution is 450 g / L.

[0016] As a preferred solution, the acidity of the arsenic removal reaction is 3.3-3.8 mol / L.

[0017] As a preferred solution, the phosphite is any one of tris(nonylphenyl)phosphite, aluminum phosphite, magnesium phosphite and sodium phosphite.

[0018] As a preferred solution, the hypophosphite is sodium hypophosphite and / or potassium hypophosphite.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] 1) In the technical solution provided by the present invention, by strictly grading the arsenic-antimony mass ratio in the crude antimony chloride solution, determining the amplification factor of the arsenic removal agent and adding a corresponding amount of the arsenic removal agent, soluble arsenic salts are converted into insoluble or insoluble arsenic compounds and elemental arsenic, thereby achieving deep arsenic removal from the crude antimony chloride solution;

[0021] 2) In the technical solution provided by the present invention, only phosphite or hypophosphite is used as a single dearsenicizing agent. Under the premise of ensuring the acidity of the dearsenicizing reaction is 3.3 to 3.8 mol / L, soluble arsenic salts are converted into insoluble arsenides, thereby achieving deep dearsenicization of the crude antimony chloride solution. After testing, the arsenic content in the antimony chloride solution after dearsenicization is less than 40 mg / L, and the arsenic removal rate reaches more than 99%;

[0022] 3) In the technical solution provided by the present invention, the amount of arsenic removal agent added must be precisely adjusted according to the mass ratio of arsenic to antimony. When the mass of arsenic and antimony in the solution is relatively small, the amplification factor of the amount of arsenic removal agent added is large. This is because the arsenic content in the solution is low and difficult to convert and precipitate. By increasing the content of the arsenic removal agent, the arsenic removal reaction is promoted to move in the forward direction, thereby removing the trace soluble arsenic salts in the solution; when the mass of arsenic and antimony in the solution is relatively large, the arsenic content in the solution is high. Under the premise of ensuring that the arsenic removal reaction proceeds in the forward direction, in order to prevent the occurrence of side reactions, a smaller amplification factor is selected to prevent the precipitated arsenide from dissolving again, thereby achieving deep arsenic removal of the solution. DETAILED DESCRIPTION

[0023] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0024] Example 1

[0025] The antimony content in a crude antimony chloride solution is 400 g / L, the arsenic content is 2.1 g / L, and the mass ratio of arsenic to antimony is 0.0053. 500 ml of the crude antimony chloride solution is taken, and the amplification factor is determined to be 1.35 based on the arsenic-antimony mass ratio. 1.25 g of sodium hypophosphite is added, and the reaction is stirred at 105°C and an acidity of 3.5 mol / L for 2 hours. After the reaction is completed, the solution is allowed to settle for 12 hours. Filtration is used to achieve solid-liquid separation. The arsenic content of the filtrate is tested to be 24 mg / L, which is less than 40 mg / L, and the arsenic removal rate is 98.8%.

[0026] Example 2

[0027] The antimony content in a crude antimony chloride solution is 400 g / L, the arsenic content is 0.7 g / L, and the mass ratio of arsenic to antimony is 0.00175. 1000 ml of the crude antimony chloride solution is taken, and the amplification factor is determined to be 2 based on the arsenic-antimony mass ratio. 1.24 g of sodium hypophosphite is added, and the reaction is stirred at 105°C and an acidity of 3.5 mol / L for 2 hours. After the reaction is completed, the solution is allowed to settle for 12 hours. Filtration is used to achieve solid-liquid separation. The arsenic content of the filtrate is tested to be 22 mg / L, less than 40 mg / L, and the arsenic removal rate is 96.8%.

[0028] Example 3

[0029] The antimony content in a crude antimony chloride solution is 400 g / L, the arsenic content is 0.25 g / L, and the mass ratio of arsenic to antimony is 0.0006. 3000 ml of the crude antimony chloride solution is taken, and the amplification factor is determined to be 2.5 based on the arsenic-antimony mass ratio. 1.65 g of sodium hypophosphite is added, and the reaction is stirred at 105°C and an acidity of 3.5 mol / L for 2 hours. After the reaction is completed, the solution is allowed to settle for 12 hours. Filtration is used to achieve solid-liquid separation. The arsenic content of the obtained filtrate is tested to be 20 mg / L, which is less than 40 mg / L, and the arsenic removal rate is 92%.

Claims

1. A method for deep arsenic removal from a crude antimony chloride solution, characterized in that: include: The method comprises the following steps: determining the arsenic-antimony mass ratio in a crude antimony chloride solution and classifying the solution according to the arsenic-antimony mass ratio; adding an arsenic removal agent to the classified crude antimony chloride solution for a arsenic removal reaction, and performing liquid-solid separation to obtain a liquid phase and a solid phase; determining and correcting the arsenic content in the obtained liquid phase; wherein the arsenic removal agent is a phosphite or a hypophosphite; and classifying the crude antimony chloride solution into six grades according to the arsenic-antimony mass ratio As / Sb, which is as follows from smallest to largest: As / Sb < 0.00045, 0.00045 ≤ As / Sb < 0.0010, 0.0010 ≤ As / Sb < 0.0020, 0.0020 ≤ As / Sb < 0.0050, 0.0050 ≤ As / Sb ≤ 0.0101, and 0.0101 < As / Sb; The amount of the arsenic removal agent added is corrected according to the mass ratio of arsenic to antimony, and the addition amount is calculated as follows: Formula 1: Dearsenicizing agent addition amount = 0.881 × A × V × Cp; In formula 1, A is the amplification factor, which is dimensionless. Its corresponding amounts to the mass ratio of arsenic and antimony are 3, 2.5, 2, 1.5, 1.35 and 1.2 from small to large; V is the volume of the crude antimony chloride solution, which is in L; Cp is the arsenic content in the crude antimony chloride solution, which is in g / L.

2. The method for deep arsenic removal from a crude antimony chloride solution according to claim 1, wherein: The arsenic removal reaction process is as follows: adding a arsenic removal agent at 100-110° C. and stirring to react for 1.5-2.5 hours; after the reaction is completed, standing and settling for 10-14 hours.

3. The method for deep arsenic removal from a crude antimony chloride solution according to claim 1, wherein: The arsenic content correction process is: when the arsenic content in the obtained liquid phase is greater than 40 mg / L, the arsenic removal reaction is continued until the arsenic content in the liquid phase is less than or equal to 40 mg / L.

4. The method for deep arsenic removal from a crude antimony chloride solution according to claim 1, wherein: The antimony content in the crude antimony chloride solution is 450 g / L; the acidity of the dearsenicization reaction is 3.3-3.8 mol / L.

5. The method for deep arsenic removal from a crude antimony chloride solution according to claim 1, wherein: The phosphite is any one of tris(nonylphenyl)phosphite, aluminum phosphite, magnesium phosphite and sodium phosphite; the hypophosphite is sodium hypophosphite and / or potassium hypophosphite.