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How to prepare zinc sulfide?

wallpapers News 2021-12-23
Method 1: Add ammonium sulfide to the zinc salt solution to obtain a white precipitate of zinc sulfide, which is then refined by recrystallization.
Method 2: Add ammonium acetate to the zinc sulfate solution, and pass in hydrogen sulfide when the pH is 2 to 3 to produce precipitation. The precipitate is filtered and dried under air isolation, and a good white crystalline zinc sulfide can be obtained.
Method 3: A method for preparing fine zinc sulfide in a closed-loop cycle, which includes the following steps:
Step 1. Mix ZnO solid powder and H2SO4 solution into the first reactor. The mass ratio of the ZnO solid powder to the H2SO4 solution is 1:1.5 to 2.5, and the mass percentage concentration of H2SO4 is 20 to 25%. After reacting at a temperature of 65-75°C for 25-35 minutes, the pH value of the solution after the reaction is adjusted to 5.0-5.5 to obtain a doped ZnSO4 solution. Then, impurity removal treatment is performed on the doped ZnSO4 solution to remove the impurities nickel, molybdenum, chromium, copper, lead, and iron in the ZnSO4 solution to obtain a pure ZnSO4 solution with an impurity content of less than 0.02%.
Step 2. Add the pure ZnSO4 solution and Na2S solution obtained in step 1 into the second reactor. The mass ratio of ZnSO4 solution to Na2S solution is 2~2.5:1, and the concentration of Na2S mass percentage is 20~25%. The reaction product is separated by the first pressure filtration with a filter press, and the water content of the filter cake is not more than 30%, and the Na2SO4 The content of solid crude zinc sulfide is not more than 5%.
Step 3. Wash the crude zinc sulfide with clean water in the washing tank, and control the specific gravity of the solution after washing to be between 0 and 0.2, and the content of Na2SO4 is less than 0.15%.
Step 4. The mixed liquid in the washing tank is separated by a second filter press using filter press. The extracted solid zinc sulfide is dried at a temperature of 100-110°C and burned at a high temperature of 745-755°C for 30-50 minutes. Highly pulverized by a jet mill to obtain a fine zinc sulfide product with a particle size of 1000-1500 mesh.
Step 5. After the mixed liquid in the washing tank is separated by the second pressure filtration with a filter press, the dialysis liquid contains 0.7-1.7% sodium sulfate by mass and 0.75-0.85% zinc sulfide by mass. The wastewater is sent to the first reactor and mixed with ZnO solid powder and H2SO4 solution to achieve a closed-loop.

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