摘要
目前钨冶炼的碱分解工艺,存在用水量大、废水量大、加工成本高等问题,使钨冶炼企业面临着经济与环保的双重压力,不能继续满足行业发展需求.对此,在大量白钨焙烧分解工艺研究的基础上,提出了酸法焙烧思路,开发出了硫酸盐焙烧分解白钨工艺,一步转型生成WO_(3).由于白钨矿焙烧产物的主要杂质为Na_(2)SO_(4)与难溶CaSO_(4),可采用盐酸浸出方式进行钨钙分离,本文采用等温平衡法,考察对比了WO_(3)、CaSO_(4)与WO_(3)–CaSO_(4)在HCl–Na_(2)SO_(4)溶液中的溶解行为,结果表明:WO_(3)与CaSO_(4)在盐酸中的溶解度相差较大,CaSO_(4)在盐酸中溶解度随温度、盐酸浓度的升高而增大,在温度80℃、盐酸浓度3 mol·L^(–1)的条件下,硫酸钙在盐酸中的溶解度达到峰值55 g·L^(-1),而Na_(2)SO_(4)可显著降低CaSO_(4)在盐酸中的溶解度,缩小CaSO_(4)与WO_(3)在盐酸中的溶解差,WO_(3)溶解度则维持在0.3~3 g·L^(-1)范围内,结合目前成熟的低钨回收工艺,能将该部分溶解钨有效地回收,即控制一定的溶解条件有利于钨钙高效分离.
There are numerous issues in the mainstream process of alkali decomposition of tungsten ores,such as large water consumption,large amounts of wastewater,and high processing costs,which add the dual pressure of economic and environmental protection on smelting enterprises and prevent them from meeting the industry’s development needs.As a result of a series of studies on scheelite roasting and decomposition processes,our team innovatively proposed the use of acid roasting to develop the process of sulfate decomposition of scheelite so that CaWO4in the scheelite could be transformed directly into WO_(3).In addition to WO_(3),the roasting products contained soluble Na_(2)SO_(4)and insoluble CaSO_(4).Because CaSO_(4)can be dissolved in hydrochloric acid,it can be separated from WO_(3)via hydrochloric acid leaching to further enrich WO_(3),resulting in a higher-grade material for subsequent procedures.In the presence of Na_(2)SO_(4),its effect on the dissolution of WO_(3)or CaSO_(4)in hydrochloric acid will directly determine the separation effect of calcium and tungsten in the roasting products.Thus,using pure substances such as WO_(3),CaSO_(4),and Na_(2)SO_(4)as raw materials,the dissolution behaviors of WO_(3),CaSO_(4),and WO_(3)–CaSO_(4)in HCl–Na_(2)SO_(4)solution were investigated separately via isothermal equilibrium dissolution to investigate the effects of hydrochloric acid concentration,sodium sulfate concentration,dissolution time,and dissolution temperature on the solubility of WO_(3),CaSO_(4),and WO_(3)–CasO4in HCl–Na_(2)SO_(4)solution.The analysis shows that WO_(3)and CaSO_(4)have very different solubilities in hydrochloric acid.The solubility of CaSO_(4)in hydrochloric acid increases with temperature and hydrochloric acid concentration when the dissolution time is 0.5–2.5 h,the hydrochloric acid concentration is 1–5 mol·L^(-1),the molar ratio of HCl and Na_(2)SO_(4)is 1∶2–2∶1,and the dissolution temperature is 40–80℃.The solubility of calcium sulfate in hydrochloric acid increases with the increase in temperature and hydrochloric acid concentration.When the temperature is 80℃and the concentration of hydrochloric acid is 3 mol·L^(-1),the solubility of calcium sulfate in hydrochloric acid reaches a peak of 55 g·L^(-1).Due to the same ion effect,Na_(2)SO_(4)can significantly reduce the solubility of CaSO_(4)and narrow the solubility difference between CaSO_(4)and WO_(3)in hydrochloric acid.CaSO_(4)has the highest solubility in HCl–Na_(2)SO_(4)solution at 17.04 g·L^(-1).The dissolved WO_(3),whose solubility is maintained at 0.3–3 g·L^(-1),can be effectively recovered by using the current mature low-tungsten recovery process.Therefore,when CaSO_(4)and WO_(3)coexist in hydrochloric acid,increasing the concentration of hydrochloric acid and the dissolution temperature while decreasing the concentration of Na_(2)SO_(4)can increase the solubility difference between them and achieve separation.
作者
徐略渭
何秉轩
徐国钻
雷鑫
胡皓东
梁勇
刘德刚
XU Lüe-wei;HE Bing-xuan;XU Guo-zuan;LEI Xin;HU Hao-dong;LIANG Yong;LIU De-gang(Faculty of Materials Metallurgical Chemistry,Jiangxi University of Science and Technology,Ganzhou 341000,China;Chongyi Zhangyuan Tungsten Co.,Ltd.,Ganzhou 341300,China)
出处
《工程科学学报》
EI
CSCD
北大核心
2023年第6期883-889,共7页
Chinese Journal of Engineering
基金
江西理工大学清江青年英才支持计划资助项目(JXUSTQJBJ2017004)
江西省自然科学基金资助项目(20202ACBL204002)。
关键词
硫酸钙
三氧化钨
硫酸钠
盐酸
溶解度
calcium sulfate
tungsten trioxide
sodium sulfate
hydrochloric acid
solubility
