Abstract: The process consisting of direct acid leaching-extraction-back extraction-vanadium precipitation by ammonia is adopted to treat the vanadium-containing stone coal in Shaanxi Wuzhou Mining Co., Ltd..However, there are some problems in this treatment such as low vanadium precipitation rate (about 95%), high content of ammonia-nitrogen in mother liquid and high LOI in filtering cake of vanadium precipitation, high prices of liquid ammonia, difficulty in transportation, and instable quality of final product V₂O₅.To solve these problems, possibility of vanadium precipitation from back-extracting vanadium-rich liquid in Wuzhou Mining Company by ammonium salts to substitute liquid ammonia was firstly investigated in laboratory.The results showed that all three kinds of ammonium salts adopted in the laboratory obtained better vanadium precipitation effect than the liquid ammonia.Especially, ammonium bicarbonate is the best one (highest vanadium precipitation and highest purity in the final products V₂O₅, lowest ammonia-nitrogen content in mother liquid and lowest LOI of filtering cake).The suitable dosage of ammonium bicarbonate is as two times as ammonium factor.According to laboratory test results, industrial tests of ammonia bicarbonate instead of liquid ammonia are further carried out in vanadium precipitation workshop of Wuzhou Mining Company.The test results showed that its vanadium precipitation rate reached nearly 99%, and the purity of final product V₂O₅ was stabilized at 98 % or more.These verify the effectiveness of ammonium bicarbonate instead of liquid ammonia.In accordance with industrial estimates, the ammonium bicarbonate as vanadium precipitation agent may increase economic benefit by 300 million in Wuzhou Mining Company.

Key words: Vanadium extraction from stone coal, Back extraction of vanadium-rich liquid, Vanadium precipitation, Ammonium bicarbonate, Liquid ammonia