APT crystalline mother liquor’s main components are ammonium chloride, ammonium tungstate, a small amount of sulfur ions and sulfate ions. Tungsten and ammonia in mother liquor of APT crystal can be recovered by adopting one-step method, calcium hydroxide or calcium oxide as calcium source and caustic source. The one-step method has the advantages of simple process, easy availability of raw materials, and controllable cost. In a word, it provides a new way for resource utilization of APT crystalline mother liquor.
For industrial applications, it is more favorable to recover tungsten and ammonium in the mother liquor of ammonium paratungstate crystallization if higher grade of calcium hydroxide is used.
Take homemade mother liquor and industrial mother liquor as samples to carry out the experiment. The results showed that more tungsten is precipitated by one-step method, which means the recovery of tungsten is more complete. When the stoichiometric ratio of Ca2+/NH4+ is greater than 0.5, the residual NH4+ in the solution is less than 200mg/L.
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