Method for selectively separating zinc and magnesium from crystallization product of zinc hydrometallurgy solution

Abstract

The invention relates to a method for selectively separating zinc and magnesium from a zinc hydrometallurgy solution crystallization product, and belongs to the field of metallurgical solid waste recycling, the zinc hydrometallurgy solution crystallization product is dissolved in water at room temperature to obtain a mixed solution, magnesium sulfide powder is slowly and uniformly added into the mixed solution in a stirring state, a reaction is carried out at room temperature, and magnesium sulfide powder is obtained; zinc is converted into zinc sulfide and zinc hydroxide to be precipitated and separated out, liquid-solid separation is conducted, zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium and a magnesium sulfate solution containing a small amount of zinc are obtained, the zinc sulfide and zinc hydroxide solids are returned to a zinc smelting system to be utilized, and the magnesium sulfate solution is directly recycled to obtain magnesium sulfate; selective separation and resource utilization of zinc hydrometallurgy solution crystallization products zinc sulfate and magnesium sulfate are achieved, the process is simple, no waste water or waste residue is discharged, and the process is clean and environmentally friendly.

Description

Technical Field

[0001] The invention relates to a method for selectively separating zinc and magnesium from a crystallized product of a wet zinc smelting solution, and belongs to the technical field of metallurgical waste resource utilization. Background Art

[0002] During the hydrometallurgical zinc smelting process, magnesium enters the solution in the form of sulfate. If not effectively removed, it will lead to cyclic enrichment of magnesium in the solution, causing crystallization and blockage of production equipment pipelines, reduced current efficiency of electrolytic zinc deposition, and increased energy consumption. Therefore, the separation of magnesium from the hydrometallurgical zinc solution is extremely necessary.

[0003] At present, when pyrometallurgy is used to volatilize and recover zinc and to render it harmless, the energy consumption is high, and the magnesium separated by crystallization enters the pyrometallurgical water-quenching slag and cannot be utilized as a resource. In order to solve the problem of efficient separation and comprehensive recovery of zinc and magnesium in zinc-magnesium sulfate produced by pyrometallurgical treatment of wet zinc smelting solution, Chinese patent CN202510161164.0 discloses a method for separating zinc and magnesium from the crystallized product of waste electrolyte from wet zinc smelting. Ammonia water is added to the crystallized product of waste electrolyte from wet zinc smelting and the pH value of the solution system is controlled to be 11-13, so that the magnesium sulfate in the crystallized product is converted into magnesium hydroxide precipitate, and the zinc sulfate is dissolved into a zinc-ammonium complex. The zinc-ammonium complex solution is hydrothermally precipitated to produce zinc oxide at a temperature of 220-250°C and ammonia water is simultaneously evaporated and condensed. The ammonia water consumption during the treatment process is large, and the hydrothermal treatment requires a relatively high temperature to be achieved.

[0004] Therefore, it is necessary to develop a new process for selectively separating zinc and magnesium from the crystallization products of wet zinc smelting solution to achieve a clean and efficient wet treatment process with low energy consumption. Summary of the Invention

[0005] In view of the problems of high energy consumption and low resource utilization rate in the harmless treatment of zinc sulfate and magnesium crystals produced by physical crystallization of wet zinc smelting solution in the prior art, the present invention proposes a method for selectively separating zinc and magnesium from the crystallized products of wet zinc smelting solution. By utilizing the different stabilities of zinc sulfide and magnesium sulfide in aqueous solution, zinc is converted into zinc sulfide precipitate using magnesium sulfide, while magnesium is retained in the solution as magnesium sulfate, which can be crystallized and recovered and can also be directly used for ore washing in mines. The present invention can realize the separation and resource utilization of zinc sulfate and magnesium sulfate, the crystallized products of wet zinc smelting solution, and has the characteristics of high zinc and magnesium separation and resource utilization rate, high added value, simple process, no wastewater and waste residue discharge, and a clean and environmentally friendly process.

[0006] A method for selectively separating zinc and magnesium from a crystallized product of a hydrometallurgical zinc smelting solution, comprising the following steps: The crystallized product of the wet zinc smelting solution is dissolved in water at room temperature to obtain a mixed solution of zinc sulfate and magnesium sulfate. Magnesium sulfide powder is slowly and evenly added to the mixed solution under stirring, and the mixture is reacted at room temperature for 1.5 to 2 hours to convert zinc into zinc sulfide and zinc hydroxide for precipitation. Liquid-solid separation is performed to obtain zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium and a magnesium sulfate solution containing a small amount of zinc. The zinc sulfide and zinc hydroxide solids are returned to the zinc smelting system for utilization; the magnesium sulfate solution directly recycles magnesium sulfate. The present invention realizes the separation and resource utilization of the crystallized product of the wet zinc smelting solution of zinc sulfate and magnesium sulfate, has a simple process, does not discharge wastewater and waste residue, and is clean and environmentally friendly.

[0007] The crystallized product of the wet zinc smelting solution is a mixture of zinc sulfate and magnesium sulfate hydrate, which is derived from the natural crystallization or cooling crystallization product of the wet zinc smelting leachate, or the cooling crystallization or freezing crystallization product of the wet zinc smelting electrolytic waste liquid.

[0008] The mass of the water is 1 to 1.1 times the mass of the crystallized product of the hydrometallurgical zinc smelting solution, and the water needs to completely dissolve the crystallized product of the hydrometallurgical zinc smelting solution.

[0009] The mixed solution is a mixed solution of zinc sulfate and magnesium sulfate with a pH value of 2-2.5, a zinc concentration of 90-100 g / L, and a magnesium concentration of 55-60 g / L.

[0010] The stirring is slow stirring with a stirring speed of 100-200 r / min, and the precipitation of hydrogen sulfide is controlled under the premise of mixing the components.

[0011] The magnesium sulfide powder is added slowly and evenly within 1 to 1.5 hours. The amount of magnesium sulfide added is 1.1 to 1.2 times the theoretical amount, which is the amount that converts all zinc in the mixed solution into zinc sulfide.

[0012] The magnesium sulfate solution is directly recycled and magnesium sulfate is crystallized and recovered or directly used for ore washing in mines.

[0013] The beneficial effects of the present invention are as follows: (1) High separation efficiency and resource utilization rate of zinc and magnesium: The present invention utilizes the different stability of zinc sulfide and magnesium sulfide in aqueous solution, and uses magnesium sulfide hydrolysis to increase the pH value of the solution to about 7.0. Magnesium sulfide is used to convert zinc into zinc sulfide and zinc hydroxide precipitation, while magnesium is retained in the solution as magnesium sulfate, thereby achieving efficient separation and recycling of the mixture of zinc sulfate and magnesium sulfate in the wet zinc smelting crystal product.

[0014] (2) The process is clean, efficient, and waste-free: The zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium obtained in the present invention are returned to the zinc smelting system for utilization, and the magnesium sulfate solution containing a small amount of zinc obtained can be crystallized to recover magnesium sulfate (the mother liquor is returned for utilization without being discharged) or directly used for ore washing in mines, thus achieving the goal of no wastewater or waste residue discharge. DETAILED DESCRIPTION

[0015] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0016] The embodiment of the present invention takes the mixed product of zinc sulfate and magnesium sulfate hydrate produced by crystallization of hydrometallurgical zinc electrolysis waste liquid with a magnesium mass fraction of 6.11% and a zinc mass fraction of 9.94% as the treatment object, and carries out a specific implementation method.

[0017] Example 1 The mixed product of zinc sulfate and magnesium sulfate hydrate produced by crystallization of hydrometallurgical zinc electrolysis waste liquid was dissolved in water of one times its mass at room temperature to obtain a mixed solution of zinc sulfate and magnesium sulfate having a pH of 2.03, a zinc concentration of 98.41 g / L, and a magnesium concentration of 60.73 g / L; Under stirring at a speed of 200 r / min, 1.1 times the theoretical amount of magnesium sulfide powder (the theoretical amount is the amount for converting all the zinc in the mixed solution into zinc sulfide) is slowly and evenly added to the mixed solution at a uniform speed within 1 hour. The mixture is reacted at room temperature for 1.5 hours to convert zinc into zinc sulfide and zinc hydroxide, which are precipitated. Liquid-solid separation is performed to obtain zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium and a magnesium sulfate solution containing a small amount of zinc. The zinc sulfide and zinc hydroxide solids are returned to the zinc smelting system for utilization; the magnesium sulfate solution is used to directly recycle magnesium sulfate, including crystallization recovery or direct use in mine washing.

[0018] In this embodiment, the zinc recovery rate is 97.58%, and the magnesium content in the precipitated solid is 0.65wt%; the magnesium recovery rate is 94.71%, and the zinc concentration in the magnesium sulfate solution is 1.93g / L.

[0019] Example 2 The mixed product of zinc sulfate and magnesium sulfate hydrate produced by crystallization of hydrometallurgical zinc electrolysis waste liquid was dissolved in water 1.03 times its mass at room temperature to obtain a mixed solution of zinc sulfate and magnesium sulfate with a pH of 2.43, a zinc concentration of 95.53 g / L, and a magnesium concentration of 58.96 g / L; Under stirring at a speed of 100 r / min, 1.1 times the theoretical amount of magnesium sulfide powder (the theoretical amount is the amount for converting all the zinc in the mixed solution into zinc sulfide) is slowly and evenly added to the mixed solution at a uniform speed within 1.5 hours. The mixture is reacted at room temperature for 2 hours to convert zinc into zinc sulfide and zinc hydroxide, which are precipitated. Liquid-solid separation is performed to obtain zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium and a magnesium sulfate solution containing a small amount of zinc. The zinc sulfide and zinc hydroxide solids are returned to the zinc smelting system for utilization; the magnesium sulfate solution is used to directly recycle magnesium sulfate, including crystallization recovery or direct use in mine washing.

[0020] In this embodiment, the zinc recovery rate is 95.26%, and the magnesium content in the precipitated solid is 0.53wt%; the magnesium recovery rate is 95.28%, and the zinc concentration in the magnesium sulfate solution is 2.51g / L.

[0021] Example 3 The mixed product of zinc sulfate and magnesium sulfate hydrate produced by crystallization of hydrometallurgical zinc electrolysis waste liquid was dissolved in water 1.08 times its mass at room temperature to obtain a mixed solution of zinc sulfate and magnesium sulfate with a pH of 2.28, a zinc concentration of 91.12 g / L, and a magnesium concentration of 56.23 g / L; Under stirring at a speed of 150 r / min, 1.2 times the theoretical amount of magnesium sulfide powder (the theoretical amount is the amount for converting all the zinc in the mixed solution into zinc sulfide) is slowly and evenly added to the mixed solution at a uniform speed within 1.2 hours. The mixture is reacted at room temperature for 2 hours to convert zinc into zinc sulfide and zinc hydroxide, which are precipitated. Liquid-solid separation is performed to obtain zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium and a magnesium sulfate solution containing a small amount of zinc. The zinc sulfide and zinc hydroxide solids are returned to the zinc smelting system for utilization; the magnesium sulfate solution is used to directly recycle magnesium sulfate, including crystallization recovery or direct use in mine washing.

[0022] In this embodiment, the zinc recovery rate is 96.15%, and the magnesium content in the precipitated solid is 0.59 wt %; the magnesium recovery rate is 94.98%, and the zinc concentration in the magnesium sulfate solution is 2.06 g / L.

[0023] The above describes the specific embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A method for selectively separating zinc and magnesium from a crystallized product of a wet zinc smelting solution, characterized in that: The specific steps are as follows: The crystallized product of the wet zinc smelting solution is dissolved in water at room temperature to obtain a mixed solution of zinc sulfate and magnesium sulfate; magnesium sulfide powder is added to the mixed solution under stirring, and the mixture is reacted at room temperature for 1.5 to 2 hours to convert zinc into zinc sulfide and zinc hydroxide, which are precipitated. Liquid-solid separation is performed to obtain zinc sulfide and zinc hydroxide solids mixed with a small amount of magnesium and a magnesium sulfate solution containing a small amount of zinc. The solid is returned to the zinc smelting system for utilization, and the solution is directly recycled for magnesium sulfate.

2. The method for selectively separating zinc and magnesium from the crystallized product of hydrometallurgical zinc smelting solution according to claim 1, characterized in that: The stirring speed is 100-200 r / min.

3. The method for selectively separating zinc and magnesium from the crystallized product of hydrometallurgical zinc smelting solution according to claim 1, characterized in that: The magnesium sulfide powder is added at a uniform speed within 1 to 1.5 hours.

4. The method for selectively separating zinc and magnesium from the crystallized product of hydrometallurgical zinc smelting solution according to claim 1, characterized in that: The amount of magnesium sulfide added is 1.1 to 1.2 times the theoretical amount.