湿法炼锌危废铁矾渣水热分解及铁物相转化行为

湿法炼锌过程产出的铁矾渣含有大量的有价金属锌、铅以及伴生金属铁,在水热条件下,危废铁矾渣将发生高效分解与转化,有价金属转入溶液,伴生铁转化为赤铁矿。本文以湿法炼锌企业产出的铁矾渣为研究对象,研究了反应温度、反应时间、液固比、初始酸度、晶种浓度等宏观技术参数对铁矾渣分解与转化的影响规律。理论计算和实验结果均表明在高温水热体系中,铁矾渣中的黄钾铁矾、黄铵铁矾和铁酸锌物相均可有效转化为赤铁矿,而铅铁矾性质稳定不易转化。升高温度并延长反应时间有利于黄钾铁矾、黄铵铁矾和铁酸锌物相的水热分解与转化。在220℃下反应1 h后,铁矾物相转化基本完成,其转化率达94%;反应4 h后铁酸锌物相衍射峰完全消失,锌浸出率达87%,转化渣中赤铁矿含量达68%。适当提高初始酸度有利于铁酸锌的转化,但当体系初始酸度高于15 g/L时将抑制铁矾物相转化。在反应温度220℃、反应时间4 h、液固比(mL/g) 10:1、初始酸度0.01 g/L的条件下,锌浸出率为89%,铁矾物相的转化率可达95%,铁矾转化渣中主要物相为赤铁矿,其含量为68%。

Hydrothermal decomposition of hazardous jarosite residue produced in zinc hydrometallurgy and transformation behavior of iron containing phase

The jarosite produced in the process of zinc hydrometallurgy contains a large amount of valuable metal Zn,Pb and associated metal Fe.Under hydrothermal conditions,the jarosite will decompose and transform efficiently,the valuable metal will be transferred into solution,and the associated Fe will be transformed into hematite.In this paper,the jarosite produced by the zinc-iron separation process in the wet zinc smelting enterprise was taken as the research object,the effects of macroscopic technical parameters such as reaction temperature,reaction time,liquid-solid ratio,acidity and crystalline concentration on the decomposition and transformation of jarosite and zinc ferrite phases in precipitates were studied.Theoretical calculation and experimental results show that in high-temperature hydrothermal system,jarosite,ammoniojarosite and zinc ferrite phase in jarosite slag can be effectively transformed into hematite,while the plumbojarosite are stable and difficult to be transformed.Increasing the temperature and prolonging the reaction time are beneficial to the hydrothermal decomposition and transformation of the phase of jarosite,ammoniojarosite and zinc ferrite.After reaction of 1 h at 220℃,jarosite phase transformation is basically completed,the conversion rate is 94%;and after the reaction of 4 h,the diffraction peak of zinc ferrite phase disappears completely,zinc leaching rate is 87%,and the transformation of precipitates in hematite content is 68%.Appropriately increasing the acidity of the system is conducive to the transformation of zinc ferrite,but when the initial acidity of the system is higher than 15 g/L,the phase transformation of ferrite will be inhibited.Under the conditions of reaction temperature of 220℃,reaction time of 4 h,liquid-solid ratio(mL/g)of 10:1,and initial acidity of 0.01 g/L,the zinc leaching rate is 89%,the conversion rate of jarosite phase can reach 95%.Hematite is the main phase in precipitates,and its content is 68%.