Method for deep antimony removal from tungstate solution

Abstract

This invention belongs to the field of purification and impurity removal technology, and discloses a method for deep antimony removal from tungstate solutions. Without affecting product quality, this invention adjusts the acidity directly or by evaporating ammonia to remove impurities from the tungstate solution, ensuring no ammonium paratungstate precipitates during the process, thus reducing energy consumption and saving costs. The deep antimony removal method provided by this invention can remove antimony from tungstate solutions to below 8 ppm.

Description

Technical Field

[0001] The invention belongs to the technical field of purification and impurity removal, and in particular relates to a method for deep antimony removal of a tungstate solution. Background Art

[0002] With the continuous development and utilization of tungsten resources, high-quality tungsten resources are constantly consumed, the utilization of complex multi-metallic associated tungsten ores is becoming more and more common, and the problem of impurity removal is becoming increasingly prominent. No matter which tungsten ore decomposition and extraction technology is used, the resulting tungstate solution still contains relatively high levels of impurity elements such as antimony, molybdenum, arsenic, and tin. In recent years, users have increasingly stringent requirements on the impurity content in tungsten metallurgical products such as ammonium paratungstate. The APT-0 grade products specified in my country's GB / T 10116-2007 contain no more than 5ppm, 20ppm, 10ppm, and 2ppm of antimony, molybdenum, arsenic, and tin, respectively. Therefore, the study of efficient and economic deep removal of the above impurities from tungstate solutions has become an important topic in the tungsten metallurgical process. In order to deeply remove the above impurities from tungstate solutions, the main method is currently the selective precipitation method. For example, the patent document with the publication number CN1203279A discloses a method for precipitating and removing molybdenum, arsenic, antimony, and tin from a tungstate solution. The method proposes adding S to a tungstate solution with a pH value of 6-6.5. 2- or HS - Sulfidation is performed to convert all impurities such as molybdenum, arsenic, antimony, and tin into corresponding thioates, and then copper-containing substances are added to the above-mentioned thioated tungstate solution as precipitants. The corresponding impurity thioates are combined with copper to form insoluble compound precipitations, and the precipitate containing impurity elements is separated from the tungstate solution. The filtrate is a pure tungstate solution, but this method has a high removal rate for molybdenum, tin, and arsenic, while the removal rate for antimony is low. The antimony removal rate of this method for high-antimony ammonium tungstate solution is actually less than 50%. The patent document with publication number CN107447119A discloses a method for removing antimony, molybdenum, arsenic, and tin from a tungstate solution. The method utilizes the difference in the sulfidation behavior of antimony and molybdenum, arsenic, and tin to preferentially remove antimony by sulfidation precipitation. The method proposes adding a sulfiding agent of 2-4 times the amount of antimony substance to the tungstate solution under alkaline conditions for sulfidation, and leaving it for 6-8 hours. The antimony is reduced and completely sulfided, mainly to SbS 2- In the form of copper or iron, a precipitant containing copper or iron is added to it to react and generate copper antimony ore (CuSbS 2 ) or iron antimony ore (FeSb 2 S 4), deeply remove the antimony in the solution, then filter, further remove molybdenum, arsenic and tin in the filtrate, add 6-10 times the amount of the total amount of molybdenum, arsenic and tin to the filtrate for sulfidation, let it stand for 6-8h, add copper-containing precipitant again after sufficient sulfidation, the corresponding impurity thioacid radicals are combined with copper to form insoluble compound precipitation, the precipitate containing impurity elements is separated from the tungstate solution, and the filtrate is pure tungstate solution. This method repeats the selective precipitation method twice, the operation time is long, the first step of sulfidation requires high precision, and it is impossible to accurately control only antimony sulfidation. Other impurity elements will compete with antimony for sulfidation, affecting the antimony removal effect. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for deep antimony removal from a tungstate solution, which has simple operation, easy controllable conditions and low cost.

[0004] The present invention creatively finds that the antimony in the tungstate solution can be deeply removed by adopting the following technical scheme.

[0005] A method for deep antimony removal from a tungstate solution comprises the following steps:

[0006] (1) Add a sulfiding agent to the tungstate solution to fully sulfide the Mo, Sb, As, and Sn in the solution into MoS 4 2- , SbS 4 3- , AsS 4 3- 、SnS 3 2- ; Then add a copper-containing precipitant to generate a precipitate; after solid-liquid separation, obtain filtrate A;

[0007] (2) Adjustment of free S in filtrate A 2- The concentration is less than 100ppm, the pH value is 6~8, and after stirring for a certain period of time and standing, a red precipitate and a tungstate solution with deep antimony removal are obtained after solid-liquid separation.

[0008] Preferably, in step (2), the temperature of the filtrate A can be further controlled to be 60-95° C., and the filtrate A can be cooled naturally while standing.

[0009] At the same time, during the research process, it was creatively discovered that the following steps can be used to replace step (2) in the above method when purifying and removing impurities from ammonium tungstate solution:

[0010] Adjust the free S in filtrate A 2- The concentration is <100ppm, and then the filtrate A is placed in a crystallization pot at a temperature >50°C to evaporate ammonia. When the pH value of the filtrate A drops to 7-8, it is allowed to stand and cool naturally, and filtered to separate the red precipitate and the deeply antimony-removed tungstate solution.

[0011] It should be noted that, while evaporating ammonia to control the pH value of the filtrate A, the precipitation of ammonium paratungstate should be prevented.

[0012] Compared with the prior art, the present invention has the following technical effects:

[0013] The above two methods for deep antimony removal provided by the present invention, by adjusting the concentration of free sulfide ions and pH value in the tungstate solution without affecting the product quality, directly adjust the acidity or adjust the pH value by evaporating and crystallizing ammonia and ensure that no ammonium paratungstate is precipitated in the process, thereby reducing energy consumption and saving costs.

[0014] The deep antimony removal method provided by the present invention can remove the antimony in the tungstate solution to below 8 ppm. DETAILED DESCRIPTION

[0015] The present invention is described in detail below. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0016] Example 1

[0017] ① The pH value of the sodium tungstate solution is 10. The content of W and the content of Mo, Sb, As and Sn in the sodium tungstate solution are detected and analyzed. The results are shown in Table 1.

[0018] Table 1 W content and Mo, Sb, As, Sn content in sodium tungstate solution (unit: g / L)

[0019]

[0020] ② Under normal temperature and stirring conditions, add sodium sulfide to the sodium tungstate solution for sulfidation. The amount used is theoretically sufficient to fully sulfidize Sb, Mo, As, and Sn into SbS 4 3- 、MoS 4 2- , AsS 4 3- 、SnS 3 2- 4 times the amount of the above-mentioned amount was added, stirring was stopped and the mixture was allowed to stand for 3 hours after the addition was completed, and then stirring was started again to add 4 times the theoretical amount of copper sulfate solution to completely precipitate and remove Mo, AS, Sn and Sb, and the mixture was stirred for 0.5 hours and allowed to stand for 8 hours, and solid-liquid separation was performed to obtain filtrate A. The contents of Sb, Mo, As and Sn in filtrate A were detected and analyzed, and the results are shown in Table 2.

[0021] Table 2 Contents of Sb, Mo, As and Sn in filtrate A (unit: g / L)

[0022]

[0023] Comparing the data in Table 1 and Table 2, it is not difficult to find that after the sodium tungstate solution is sulfided and copper sulfate solution is added to remove impurities, the removal effect of Sb is very unsatisfactory.

[0024] ③ Heat the temperature of filtrate A to 75-80°C, adjust the pH value of filtrate A to between 6.5 and 7 with hydrochloric acid, stir for 3 hours, let stand, separate the solid and the liquid, and obtain a red solid and a sodium tungstate solution after antimony removal.

[0025] The red solid was collected and analyzed for phase, and the results are shown in Table 3. It can be determined that the main components of the red solid are compounds of Sb and S.

[0026] Table 3 Red solid phase analysis

[0027]

[0028] The Sb content in the sodium tungstate solution after antimony removal was further analyzed and the result was 0.0078 g / L.

[0029] Example 2

[0030] ① The pH value of the ammonium tungstate solution is 9. The content of W and the content of Mo, Sb, As and Sn in the ammonium tungstate solution are detected and analyzed. The results are shown in Table 4.

[0031] Table 4 W content and Mo, Sb, As, Sn content in ammonium tungstate solution (unit: g / L)

[0032]

[0033] ② Under normal temperature and stirring conditions, add sodium sulfide to the ammonium tungstate solution for sulfidation. The amount used is theoretically sufficient to fully sulfidize Sb, Mo, As, and Sn into SbS 4 3- 、MoS 4 2- , AsS 4 3- 、SnS 3 2- 4 times the amount of the above-mentioned amount was added, stirring was stopped after the addition, and the mixture was allowed to stand for 3 hours. Then stirring was started again, and 4 times the theoretical amount of copper sulfate solution for completely precipitating and removing Mo, AS, Sn, and Sb was added. After stirring for 0.5 hours, the mixture was allowed to stand for 8 hours, and solid-liquid separation was performed to obtain filtrate A. The contents of Sb, Mo, As, and Sn in filtrate A were detected and analyzed, and the results are shown in Table 5.

[0034] Table 5 Contents of Sb, Mo, As and Sn in filtrate A (unit: g / L)

[0035]

[0036] Comparing the data in Table 3 and Table 4, it is not difficult to find that after the ammonium tungstate solution is sulfided and copper sulfate solution is added to remove impurities, the removal effect of Sb is very unsatisfactory.

[0037] ③Put the filtrate A in a crystallization pot, heat it to 80℃ to evaporate ammonia, control the pH value of the filtrate A to be close to but not less than 7, and after the red solid appears in the filtrate A, let it stand for solid-liquid separation to obtain the red solid and the ammonium tungstate solution after antimony removal.

[0038] The red solid was collected and analyzed for phase, and the results are shown in Table 6. It can be determined that the main components of the red solid are compounds of Sb and S.

[0039] Table 6 Red solid phase analysis

[0040]

[0041] The Sb content in the ammonium tungstate solution after antimony removal was further analyzed and the result was 0.008 g / L.

[0042] Example 3

[0043] ① The pH value of the sodium tungstate solution is 10. The content of W and the content of Mo, Sb, As and Sn in the sodium tungstate solution are detected and analyzed. The results are shown in Table 7.

[0044] Table 7 W content and Mo, Sb, As, Sn content in sodium tungstate solution (unit: g / L)

[0045]

[0046] ② Under normal temperature and stirring conditions, add sodium sulfide to the sodium tungstate solution for sulfidation. The amount used is theoretically sufficient to fully sulfidize Sb, Mo, As, and Sn into SbS 4 3- 、MoS 4 2- , AsS 4 3- 、SnS 3 2- 4 times the amount of the above-mentioned amount was added, stirring was stopped after the addition, and the mixture was allowed to stand for 3 hours. Then stirring was started again, and 4 times the theoretical amount of copper sulfate solution for completely precipitating and removing Mo, AS, Sn, and Sb was added. After stirring for 0.5 hours, the mixture was allowed to stand for 8 hours, and solid-liquid separation was performed to obtain filtrate A. The contents of Sb, Mo, As, and Sn in filtrate A were detected and analyzed, and the results are shown in Table 8.

[0047] Table 8 Contents of Sb, Mo, As and Sn in filtrate A (unit: g / L)

[0048]

[0049] Comparing the data in Table 7 and Table 8, it is not difficult to find that after the sodium tungstate solution is sulfided and copper sulfate solution is added to remove impurities, the removal effect of Sb is very unsatisfactory.

[0050] ③ Heat the temperature of filtrate A to 75-80°C, adjust the pH value of filtrate A to between 7 and 8 with hydrochloric acid, stir for 3 hours, let stand, separate the solid and the liquid, and obtain a red solid and a sodium tungstate solution after antimony removal.

[0051] The Sb content in the sodium tungstate solution after antimony removal was further analyzed and the result was 0.0046 g / L.

[0052] The contents not described in detail in the specification are prior art known to those skilled in the art.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for deep antimony removal from tungstate solution, characterized in that: The following steps are involved: (1) Add a sulfiding agent to the tungstate solution to fully sulfide the Mo, Sb, As, and Sn in the solution into MoS4 2- 、SbS4 3- 、AsS4 3- SnS3 2- ; Then add a copper-containing precipitant to generate a precipitate; after solid-liquid separation, obtain filtrate A; (2) Adjustment of free sulfur in filtrate A 2- The concentration is less than 100ppm, the pH value is 6~8, and after stirring for a certain period of time and standing, a red precipitate and a tungstate solution with deep antimony removal are obtained after solid-liquid separation.

2. The method for deep antimony removal from tungstate solution according to claim 1, characterized in that: In step (2), the temperature of the filtrate A is controlled to be 60-95° C., and the filtrate A is cooled naturally while being allowed to stand.

3. A method for deep antimony removal from tungstate solution, characterized in that: The following steps are involved: (1) Add a sulfiding agent to the tungstate solution to fully sulfide the Mo, Sb, As, and Sn in the solution into MoS4 2- 、SbS4 3- 、AsS4 3- SnS3 2- ; Then add a copper-containing precipitant to generate a precipitate; after solid-liquid separation, obtain filtrate A; (2) Adjustment of free sulfur in filtrate A 2- The concentration is <100ppm, and then the filtrate A is placed in a crystallization pot at a temperature >50°C to evaporate ammonia. When the pH value of the filtrate A drops to 7-8, it is allowed to stand and cool naturally, and filtered to separate the red precipitate and the deeply antimony-removed tungstate solution.

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