Recovery Plan for Molybdenum Slag Removal

The chemical properties of tungsten and molybdenum are similar, and they are often associated with each other in nature. In the current tungsten smelting process, the separation of tungsten and molybdenum has become a very important process, among which the selective precipitation method is the most concerned.

Molybdenum removal by selective precipitation method is based on the fact that MoS₄^2- has the property of sulfur affinity and can react with sulfide to form precipitation, while WO₄^2- is not sulfur affinity, thus realizing the separation of tungsten and molybdenum in solution. The process is characterized by short process flow, simple operation, high molybdenum removal efficiency and less tungsten loss. It has become the main method for molybdenum removal in tungsten smelting enterprises in China.

For molybdenum removal slag containing a large amount of copper, Mo and a small amount of W, the following recovery schemes can be adopted:

After drying and grinding the molybdenum-removal wet residue and passing through 300 mesh sieve, 50 g of sieve material and ammonia water with a concentration of 10 mol/L at 500 ml were added into the autoclave. The oxygen partial pressure in the autoclave was controlled to be 2.5 Mpa. The solid-liquid separation was carried out after 10 hours of reaction at 60 ℃. The leaching rates of copper, Mo and WO₃ in the molybdenum-removal residue were 98.8%, 98% and 96.2% respectively. The filtrate was flowed through ion exchange column with strong alkaline anion exchange resin. After evaporation and concentration, the solution containing Cu²⁺100g/L was obtained and returned to the selective precipitation and molybdenum removal process; the resin was washed with deionized water, and the washed water was returned to ammonia water for oxygen pressure ammonia leaching; the resin was desorbed with a mixed solution of 5 mol/L ammonium chloride and 2 mol/L ammonia water, and the mixed solution containing a large amount of ammonium molybdate and a small amount of ammonium tungstate was separated from molybdenum and tungsten to produce molybden products and tungsten products.

The above process simplifies the treatment process of copper in molybdenum slag, realizes the resource reuse of copper, greatly reduces the reagent cost of molybdenum removal process; the solution containing Mo and W obtained by resin desorption can be used in the production of molybdenum products and tungsten products. Moreover, the whole process is short, easy to operate, environmentally friendly, high resource recovery, low production cost and easy to industrialize.

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