含锗锌浸出渣加压强化浸出及铁沉淀行为

Pressure enhanced leaching and iron precipitation behavior of germanium containing zinc leaching residue

针对锌浸出渣处理过程中存在有价金属回收率低、危废铁渣量大等关键技术难题,本文提出了锌浸出渣Ⅰ段控铁低酸加压浸出−Ⅱ段深度高酸加压浸出的两段逆流加压酸浸工艺路线。以某湿法炼锌企业产出的含锗锌浸出渣为研究对象,重点研究了Ⅰ段控铁加压低酸浸出过程中锌、锗、铁的浸出行为,铁的高温水解沉淀行为以及铁物相演变规律。结果表明:温度是影响铁高效沉淀与铁物相组成的关键因素,升高温度能促进Fe^(3+)水解生成铁矾(MFe_(3)(SO_(4))_(2)(OH)_(6)),并有利于铁酸盐(MeFe_(2)O_(4))的溶解。降低初始酸度、延长反应时间均有利于铁矾晶体的发育长大;在高酸体系下,铁矾的热力学稳定性降低,且不利于Fe^(3+)的水解沉淀,但通过升高反应温度可使Fe^(3+)水解生成铁矾和赤铁矿(Fe_(2)O_(3))等沉铁物相,达到铁高效沉淀分离的目的;因锌浸出渣中铁主要以Fe^(3+)形式存在,故氧分压对Ⅰ段浸出过程中铁的沉淀分离影响不显著。在反应温度140℃、初始酸度46 g/L、反应时间180 min、氧分压0.3 MPa、液固比6 mL/g、搅拌转速500 r/min的Ⅰ段控铁低酸加压浸出优化条件下,约90%以上的铁水解沉淀为铁矾,获得了铁浓度仅为1.88 g/L的Ⅰ段浸出液,为Ⅰ段浸出液中有价金属的进一步分离提取提供有利条件。经Ⅱ段深度高酸加压浸出后,锌、铜、锗的两段总浸出率分别为96.24%、94.73%、68.76%,含锗锌浸出渣的两段逆流加压酸浸工艺可同时实现锌、铁高效分离与锌、铜、锗等有价金属的高效浸出。

Given the critical technical issues in the treatment of zinc leaching residue,such as low metal recovery and a large amount of hazardous waste iron residue,this paper proposes a two-stage countercurrent pressure acid leaching process route for zinc leaching residue,consisting ofⅠ-stage iron-controlled low acid pressure leaching andⅡ-stage deep high acid pressure leaching.Taking the germanium containing zinc leaching residue produced by a zinc hydrometallurgy enterprise as the research object,the leaching behaviors of Zn,Ge,and Fe,the hightemperature hydrolysis precipitation behavior of iron,and the evolution law of the iron phase in the process of ironcontrolled pressurized low acid leaching in stageⅠwere studied.The results show that temperature is the key factor affecting the efficient precipitation of iron and the composition of the iron phase.Increasing the temperature can promote the hydrolysis of Fe^(3+)to form jarosite(MeFe_(3)(SO_(4))_(2)(OH)_(6))and is conducive to the dissolution of ferrite(MeFe2O4).Reducing the initial acidity and prolonging the reaction time are conducive to the development and growth of jarosite crystals.In the high-acid system,the thermodynamic stability of jarosite decreases and is not conducive to the hydrolysis and precipitation of Fe^(3+).However,by increasing the reaction temperature,Fe^(3+)can be hydrolyzed to form iron precipitation phases such as jarosite and hematite(Fe_(2)O_(3)),so as to achieve the purpose of efficient precipitation and separation of iron;Because iron in zinc leaching residue is mostly in the form of Fe^(3+),the effect of oxygen partial pressure on iron precipitation and separation inⅠ-stage leaching is negligible.Under the optimized conditions ofⅠ-stage iron-controlled low acid pressure leaching with a reaction temperature of 140℃,initial acidity of 46 g/L,a reaction time of 180 min,oxygen partial pressure of 0.3 MPa,a liquid-to-solid ratio of 6 m L/g,and stirring speed of 500 r/min,more than 90%of the iron is hydrolyzed and precipitated into alum,and theⅠ-stage leaching solution with an iron concentration of only 1.88 g/L is obtained,which provide favorable conditions for the further separation and extraction of valuable metals from the leaching solution.After theⅡ-stage of deep high-acid pressure leaching,the total leaching rates of the two stages of zinc,copper,and germanium are 96.24%,94.73%,and 68.76%,respectively.The two-stage countercurrent pressure acid leaching process of the germanium containing zinc leaching residue can be realized at the same time.With the highefficiency separation of zinc and iron and high-efficiency leaching of valuable metals such as zinc,copper,and germanium under high-acid pressure leaching,the total leaching rates of the two stages of zinc,copper,and germanium are 96.24%,94.73%,and 68.76%,respectively.The two-stage countercurrent pressure acid leaching process of the germanium containing zinc leaching residue can be realized at the same time for high-efficiency separation of zinc and iron and high-efficiency leaching of valuable metals such as zinc,copper,and germanium.