Method for removing copper, manganese and zinc in P204 strip liquor

Abstract

The invention discloses a method for removing copper, manganese and zinc in P204 strip liquor, and belongs to the technical field of metal refining. The method provided by the invention comprises the following steps: (1) adding lime to adjust the pH value of the P204 strip liquor to be alkaline, and carrying out copper-zinc deposition reaction; after the reaction is finished, carrying out filter pressing to obtain a first filter residue and a first filtrate; (2) mixing the first filtrate and the P507 raffinate, then adding caustic soda liquid to adjust the pH to be alkaline, and further performing precipitation reaction on copper and manganese in the solution; and after the reaction is finished, carrying out filter pressing to obtain nickel slag and a second filtrate. The method has the advantages of simple steps, low cost and high safety, reduces the burden of waste liquid treatment, and has good applicability in industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of metal refining, and in particular to a method for removing copper, manganese and zinc from P204 stripping solution. Background Art

[0002] P204 is the full name of bis(2-ethylhexyl) phosphate, which is an industrial extractant widely used in the separation of rare earth elements and the extraction of non-ferrous metals. Its chemical name is Di-(2-ethylhexyl)phosphoric acid, and its molecular formula is C 16 H 35 O4P, molecular weight is 322.4205.

[0003] The leaching step in cobalt-nickel smelting is the process of transferring the valuable metals in the cobalt-nickel ore into the solution through chemical reactions. This process usually uses acid or other chemical reagents to dissolve the metals in the ore, turning them into ionic forms that are soluble in water, so as to facilitate subsequent separation and purification. After the leaching step, P204 is usually selected to extract impurities (such as copper, manganese, and zinc). After the extraction is completed, inorganic acids (such as sulfuric acid, etc.) can be used for stripping to obtain P204 stripping solution. During the recovery and treatment of the P204 stripping solution, the remaining copper, zinc, and manganese elements need to be removed.

[0004] For example, the applicant's research and development team disclosed a method for removing copper and zinc from P204 stripping solution by a cobalt-nickel hydrometallurgical process in a Chinese invention patent with publication number CN117089717A, which includes the following steps: (1) copper precipitation: adding a liquid alkali solution to the P204 stripping solution, adjusting the pH to 6.6-6.8, and performing a copper precipitation reaction; filtering after the reaction is completed to obtain copper hydroxide slag and a first filtrate; (2) copper and zinc precipitation: adding sodium sulfide to the first filtrate to perform a copper and zinc precipitation reaction; filtering after the reaction is completed to obtain copper sulfide zinc slag and a second filtrate; (3) calcium and magnesium precipitation: adding sodium fluoride to the second filtrate to perform a calcium and magnesium precipitation reaction; filtering after the reaction is completed to obtain calcium fluoride magnesium slag and a P204 stripping solution after impurities are removed. This method reduces the risk of endothermic spontaneous combustion of copper sulfide during the reaction process and reduces production risks. However, sodium sulfide is used in the copper and zinc precipitation process. Sodium sulfide is easily generated by dissolving in water. Hydrogen sulfide is a colorless and highly toxic acidic gas. Sodium fluoride is used when precipitating calcium and magnesium, which will result in fluoride ions in the wastewater that cannot be removed, increasing the burden of wastewater treatment.

[0005] The applicant's research and development team provides a method for removing copper and zinc from the P204 stripping solution of the nickel-cobalt hydrometallurgical process in the Chinese invention patent with publication number CN115404343A. The method adopts a one-stage alkali precipitation and a two-stage resin adsorption method. The first stage of alkali precipitation is to add an alkaline solution to the stripping solution to precipitate most of the copper and zinc in the form of hydroxides, leaving only a small amount of copper and zinc; after the solid-liquid separation of the first stage of alkali precipitation liquid, the filtrate enters the second stage of chelating resin adsorption, and then enters the back-end process after the chelating resin adsorption; when the resin adsorption is saturated, desorption is performed, and the desorption liquid is a high content of copper and zinc and a low content of manganese, thereby achieving two-stage copper and zinc removal, avoiding the addition of sodium sulfide, and solving the safety risk problem of flammable sulfides. However, the process uses chelating resin for adsorption, and as the use time increases, the surface of the chelating resin will be adsorbed by a large amount of metal ions, resulting in saturation of exchange sites, thereby affecting the performance. In addition, the preparation and production costs of the chelating resin are high, and regeneration is required after adsorption saturation for reuse. The regeneration process of chelating resin is relatively complicated and requires the use of a specific regeneration agent, which will increase the cost and time of operation and maintenance, limiting its application in industrial-scale treatment.

[0006] In summary, providing a method for removing copper, manganese and zinc in P204 stripping solution with low cost, simple operation, low safety hazard and easy industrial-scale processing is of great significance for expanding the application in this field. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, a method for removing copper, manganese and zinc from P204 stripping solution with simple steps, low cost and high safety is provided, comprising the following steps: (1) adding lime to adjust the pH of the P204 stripping solution to be alkaline, and performing a copper-zinc precipitation reaction; after the reaction is completed, performing filter pressing to obtain a first filter residue and a first filtrate; (2) The first filtrate and the P507 raffinate are combined, and then liquid caustic soda is added to adjust the pH to alkaline, so as to further precipitate the copper and manganese in the solution; after the reaction is completed, the mixture is filtered to obtain a second filter residue and a second filtrate.

[0008] Preferably, in step (1), the P204 stripping solution is a P204 stripping solution produced by a cobalt-nickel hydrometallurgical process.

[0009] At different pH values, the binding ability of metal ions and hydroxide ions is different, thus affecting the formation of precipitation. The pH value will affect the speed of precipitation reaction. At different pH values, the binding speed of copper and zinc ions and hydroxide ions is different, thus affecting the speed of precipitation reaction. Therefore, controlling the pH value within the range of 9.0-9.5 can adjust the speed of precipitation reaction, thereby achieving control of copper and zinc precipitation reaction.

[0010] Preferably, in step (1), the pH of the P204 stripping solution is adjusted to 9.0-9.5.

[0011] Temperature has an impact on the rate of precipitation reaction and the quality of the product. Too low a temperature will cause the rate of precipitation reaction to be too slow, prolonging the reaction time, which is not conducive to improving production efficiency; and it will cause incomplete precipitation, so that the product still contains unprecipitated metal ions, and too high a temperature may cause adverse chemical reactions, affecting the quality of the precipitation layer. The present invention is based on the method of lime precipitation, and the precipitation temperature is appropriately controlled within a suitable range, and the temperature is controlled to achieve the precipitation of the target metal ions, thereby achieving the separation of the metal ions. When no further precipitation is generated in the reaction system, the reaction is considered to be completed, and those skilled in the art can select a suitable duration according to the actual reaction scale.

[0012] Preferably, in step (1), the temperature of the copper-zinc deposition reaction is 50-60°C.

[0013] Preferably, in step (2), the volume ratio of the first filtrate to the P507 raffinate is 2-3:7-8.

[0014] Similar to the copper-zinc precipitation reaction, the pH value of the precipitation reaction of copper and manganese in the solution is preferably controlled in the range of 10.5-11.0. In this pH range, the concentration of hydroxide ions is relatively high, and for the remaining copper ions, the reaction proceeds in the direction of forming precipitation; for manganese ions, it is easy to form more stable high-valent manganese oxide or hydroxide precipitation, so that the two ions are effectively removed.

[0015] Preferably, in step (2), liquid alkali is added to adjust the pH to 10.5-11.0.

[0016] Preferably, in step (2), the precipitation reaction temperature is 50-60°C.

[0017] Preferably, in step (2), the copper and manganese contents in the second filter residue are both less than 0.01 g / L.

[0018] In the art, the residual liquid after extraction and impurity removal by the P204 extractant system enters the P507 system for cobalt and nickel separation. After nickel is extracted from P507, P507 raffinate is obtained. P507 raffinate usually contains more nickel (about 500 mg), cobalt (about 70 mg), and other impurities with lower content, such as Mn.

[0019] The present invention uses lime to replace liquid alkali for copper-zinc precipitation reaction, which greatly reduces the processing cost. The accumulation of copper, zinc and manganese ions in the environment may have a negative impact on the ecosystem, and these metal ions may pose a potential threat to human health. In addition, copper, zinc and manganese ions also have certain economic value, and their separated filter residues can also be used for further recycling and processing. Whether from the perspective of environmental impact, health risk or resource recovery, the three metal ions have the necessity of treatment or recovery. In comparison, calcium ions are widely present in natural rocks and organisms, and are not as harmful as general heavy metals; in the application scenario of the invention, the calcium ions introduced by lime do not produce corresponding negative effects. Considering that lime is a weak base, the subsequent precipitation of the remaining manganese in the first filtrate (copper-manganese liquid) is complete, and even if a large amount of lime needs to be added, the pH requirement of the precipitation reaction cannot be achieved, which causes a waste of auxiliary material cost and a large amount of manganese loss in the first filtrate. Therefore, the present invention combines the first filtrate and the P507 raffinate, and uses liquid alkali for precipitation, which shortens the processing time and cost of the copper-manganese liquid route.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects: The invention provides a method for removing copper, manganese and zinc in a P204 stripping solution, which has the advantages of simple steps, low cost and high safety, reduces the burden of waste liquid treatment and has good applicability in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the process flow of the embodiment. DETAILED DESCRIPTION

[0022] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0023] Example 1 Methods for removing copper, manganese and zinc from P204 stripping solution, such as Figure 1 As shown, the steps are as follows: (1) adding lime to adjust the pH of the P204 stripping solution to 9.0, and performing copper-zinc precipitation reaction at a reaction temperature of 50°C; after the reaction is completed, performing filter pressing to obtain a first filter residue (lime precipitate residue) and a first filtrate; (2) The first filtrate and the P507 raffinate were mixed in a volume ratio of 3:7, and then liquid alkali was added to adjust the pH to 10.5, and the copper and manganese in the solution were further precipitated at a temperature of 50 °C. After the reaction was completed, the solution was filtered to obtain a second filter residue (nickel residue) and a second filtrate.

[0024] Example 2 The method for removing copper, manganese and zinc from P204 stripping solution is as follows: (1) adding lime to adjust the pH of the P204 stripping solution to 9.5, and performing copper-zinc precipitation reaction at a reaction temperature of 60°C; after the reaction is completed, performing filter pressing to obtain a first filter residue (lime precipitate residue) and a first filtrate; (2) The first filtrate and the P507 raffinate were mixed in a volume ratio of 2:8, and then liquid alkali was added to adjust the pH to 11.0, and the copper and manganese in the solution were further precipitated at a temperature of 60 °C. After the reaction was completed, the solution was filtered to obtain a second filter residue (nickel residue) and a second filtrate.

[0025] Comparative Example 1 In this comparative example, liquid alkali is used instead of lime for precipitation in the copper and zinc precipitation step to compare the difference between the process of the present invention and the existing process. The operation is as follows: (1) Liquid alkali is added to adjust the pH of the P204 stripping solution to 9.0, and copper and zinc precipitation reaction is carried out; after the reaction is completed, pressure filtration is performed to obtain a first filter residue (liquid alkali precipitation residue) and a first filtrate.

[0026] The content of Cu, Mn, Zn and Ca in the P204 stripping solution was tested and recorded by atomic absorption spectroscopy; in step (1) of Example 1 and Comparative Example 1, the content of the above elements in the first filtrate and the first filtrate was tested when lime was precipitated to pH = 9 and when liquid alkali was precipitated to pH = 9, respectively, and the unit consumption of lime and liquid alkali was recorded. The results of the element content and unit consumption of the first filtrate are shown in Table 1; the results of the element content of the first filter residue are shown in Table 2.

[0027] Table 1: Element content and unit consumption of the first filtrate

[0028] In the table, “ND” stands for not detected.

[0029] Table 2: Element content of the first filter residue

[0030] The Cu and Mn contents of the combined solution and the second filtrate in step (2) of Example 1 were tested and recorded. The test results are shown in Table 3.

[0031] Table 3: Cu and Mn contents of the combined solution and the second filtrate

[0032] From the above test data, it can be seen that using lime precipitation to pH = 9 can achieve a similar treatment effect as using liquid alkali precipitation to pH = 9. The amount of slag obtained by lime precipitation will increase by 10%, and the calcium content will increase at the same time. This is because there are about 4-5g / L sulfate ions in the original solution, which finally react with calcium to form calcium sulfate; the manganese content in the slag obtained by lime precipitation is about 20wt.%, which is slightly lower than the manganese content of the slag obtained by liquid alkali precipitation.

[0033] Considering the cost, if the price of lime is 1000 yuan / t, the cost of lime precipitation is 0.2×1000=200 yuan / m 3 ; Based on the price of liquid alkali of 800 yuan / ton, the cost of liquid alkali precipitation is 0.405×800=324 yuan / m 3 . Lime is used as a precipitant. 3 The invention can remove copper, manganese and zinc in P204 stripping solution with lower cost and simpler steps.

[0034] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for removing copper, manganese and zinc from P204 stripping solution, characterized in that: The steps include: (1) adding lime to adjust the pH of the P204 stripping solution to be alkaline, and performing a copper-zinc precipitation reaction; after the reaction is completed, performing filter pressing to obtain a first filter residue and a first filtrate; (2) The first filtrate and the P507 raffinate are combined, and then liquid caustic soda is added to adjust the pH to alkaline, so as to further precipitate the copper and manganese in the solution; after the reaction is completed, the mixture is filtered to obtain a second filter residue and a second filtrate.

2. The method for removing copper, manganese and zinc from P204 stripping solution according to claim 1, characterized in that: In the step (1), the P204 stripping solution is a P204 stripping solution produced by a cobalt-nickel hydrometallurgical process.

3. The method for removing copper, manganese and zinc from P204 stripping solution according to claim 1, characterized in that: In the step (1), the pH of the P204 stripping solution is adjusted to 9.0-9.

5.

4. The method for removing copper, manganese and zinc from P204 stripping solution according to claim 1, characterized in that: In the step (1), the temperature of the copper-zinc deposition reaction is 50-60°C.

5. The method for removing copper, manganese and zinc from P204 stripping solution according to claim 1, characterized in that: In the step (2), the volume ratio of the first filtrate to the P507 raffinate is 2-3:7-8.

6. The method for removing copper, manganese and zinc from P204 stripping solution according to claim 1, characterized in that: In the step (2), liquid alkali is added to adjust the pH to 10.5-11.

0.

7. The method for removing copper, manganese and zinc from P204 stripping solution according to claim 1, characterized in that: In the step (2), the temperature of the precipitation reaction is 50-60°C.

8. The method for removing copper, manganese and zinc in P204 stripping solution according to claim 1, characterized in that: In the step (2), the copper and manganese contents in the second filter residue are both less than 0.01 g / L.

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