(中南大學(xué) 冶金與環(huán)境學(xué)院，長沙 410083)
摘 要: 利用雙氧水易與鎢形成可溶性過氧鎢酸的特性，提出了雙氧水(H2O2)協(xié)同鹽酸分解人造白鎢(CaWO4)的新工藝，使CaWO4以氯化鈣(CaCl2)和過氧鎢酸(H4[WO3(O2)2])的形式溶解到浸出體系中，大幅提高了人造白鎢的分解率。研究鹽酸和雙氧水濃度、反應(yīng)溫度、液固比及反應(yīng)時間等因素對人造白鎢分解效果的影響。結(jié)果表明：在H2O2存在的情況下，鹽酸用量可大幅降低，所用的鹽酸初始濃度很低故揮發(fā)損失很少；H2O2濃度的增加有利于反應(yīng)的進(jìn)行；當(dāng)溫度低于30 ℃時，升高溫度對人造白鎢的分解浸出有明顯的促進(jìn)作用，超過40 ℃后H2O2會逐漸分解且產(chǎn)物過氧鎢酸變得不穩(wěn)定反而不利于浸出。得到的較優(yōu)條件如下：H2O2濃度2.4 mol/L，鹽酸濃度1.5 mol/L，溫度30 ℃，液固比10:1(mL/g)，反應(yīng)時間40 min。在此條件下，人造白鎢實(shí)現(xiàn)了完全分解。
關(guān)鍵字: 人造白鎢；鹽酸；雙氧水；過氧鎢酸
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:A new process was proposed for the digestion of synthetic scheelite (CaWO4) in hydrochloric acid solution using hydrogen peroxide (H2O2) as complexing agent. H2O2 as a chelating agent, can readily react with H2WO4 to form water-soluble peroxotungstic acid H4[WO3(O2)2], and the conversion rate of WO3 was raised substantially. The effects of relevant parameters, such as the concentrations of HCl and H2O2, reaction temperature, liquid-to-solid ratio and reaction time, were studied. The results show that increasing the concentration of H2O2 benefits the process and both the concentrate and consumption of HCl drastically drop and the volatility loss of HCl reduces noticeably. Elevating the temperature promotes the decomposition of CaWO4 below 30 ℃ while becomes unfavorable above 40 ℃ because the stability of H2O2 and peroxotungstic acid gradually decreases. The optimum process conditions are as follows: the concentrations of H2O2 and HCl are 2.4 and 1.5 mol/L, respectively, the temperature is 30 ℃, the liquid-to-solid ratio is 10:1 (mL/g), and the reaction time is 40 min. Under these conditions the synthetic scheelite can be completely decomposed.
Key words: synthetic scheelite; hydrochloric acid; hydrogen peroxide; peroxotungstic acid
