Recycling Ammonium Paratungstate, Cobalt, Nickel from Waste Tungsten Carbide

With the economic developing rapidly, tungsten carbide used in each industry is being more and more widely, thus leading a huge demand and consumption of tungsten. The metal composition of carbide is almost rare metal elements, and tungsten takes a large proportion. The more consumption of carbide means the more consumption of rare metals, in this case, recover tungsten and other rare metals is extremely important.
 
The steps of recovery waste tungsten carbide are like bellows:
1. Melting tungsten carbide
Pour the waste tungsten carbide scrap into a furnace, and adding sodium bicarbonate or sodium carbonate, then heating to 800~1200℃ to get carbide mixture;
2. Preparation of sodium tungstate
Pour the carbide mixture into water to generate a solution containing with sodium tungstate and precipitate, and then filter to separate sodium tungstate solution and solid matter;
3. Preparation of ammonium paratungstate
Sodium tungstate solution goes through extraction and adding ammonia to generate ammonium tungstate solution, heating to evaporate APT crystal;
Further more, the APT is dried, and calcination to obtain tungsten oxide, and then reduced to tungsten powder in a hydrogen atmosphere;
4. Extract cobalt, nickel and other metals from the solids
1) Mix the solid with hydrochloric acid solution (concentration of 10-30%), and then filter to separate the precipitate and liquid;
2) Taking liquids, removing the impurities of iron, and then carrying out extraction to separate liquids containing with cobalt and nickel;
3) Add ammonium oxalate solution respectively into the liquids containing with cobalt and nickel, and precipitation, filtration, evaporation and drying after the reaction is completed, to obtain solids that cobalt and nickel oxalate, then reduced to obtain cobalt and nickel powder;
4) Take the precipitate to calcine and melt for second time, and then get tantalum and niobium by dissolving it in water.

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