摘要
The extraction of tungsten from scheelite was carried out using a sulfuric acid solution with oxalic acid as the chelating agent.Tungsten was obtained in the form of highly soluble hydrogen aqua oxalato tungstate H_(2)[WO_(3)(C_(2)O_(4))·H_(2)O] during the leaching process,while calcium remained in the residue as calcium sulfate dihydrate(CaSO4·2H2O).About 99.2%of the tungsten was leached at 70℃,1.5 mol/L sulfuric acid,1 mol/L oxalic acid,a liquid/solid ratio of 25:1(mL/g),an oxalic acid to sulfuric acid molar ratio of 1:1,a stirring speed of 300 r/min and a leaching time of 2 h.H_(2)[WO_(3)(C_(2)O_(4))·H_(2)O]was thermally decomposed into tungstic acid(H_(2)WO_(4)),and tungsten trioxide(WO_(3))was directly produced by calcining H_(2)WO_(4) at 700℃ for 2 h.The surface chemical reaction was determined to be the controlling step during tungsten leaching,and the apparent activation energy was calculated to be 51.43 kJ/mol.
以草酸为络合剂,利用硫酸从白钨矿中提取钨。在浸出过程中,钨以高水溶性H_(2)[WO_(3)(C_(2)O_(4))·H_(2)O]的形式完全浸出,而钙则以CaSO_(4)·2H_(2)O的形式残留在渣中。在温度70℃、1.5 mol/L硫酸、1 mol/L草酸、液固比25:1(mL/g)、草酸/硫酸摩尔比1:1、搅拌速度300 r/min、浸出时间2 h的条件下,钨的浸出率为99.2%。H_(2)[WO_(3)(C_(2)O_(4))·H_(2)O]经热分解转化为H_(2)WO_(4),H_(2)WO_(4)在700℃下焙烧2 h,可直接分解成WO3。冶金动力学研究表明,白钨矿浸出过程由表面化学反应控制,其表观活化能为51.43 kJ/mol。
基金
financial supports from the National Natural Science Foundation of China (Nos.51564019, 51674125)
Science and Technology Project of Jiangxi Provincial Education Department,China (No.GJJ181501).
