硫化锌精矿与锌浸出渣协同助浸机理及行为

Mechanism and behavior of synergistic leaching of zinc sulfide concentrate and zinc leaching residue

针对硫化锌精矿两段氧压浸出能耗高、锌浸出渣处理产生危废铁渣量大等行业技术难题,提出硫化锌精矿与锌浸出渣协同助浸工艺,利用锌浸出渣中高价铁的载氧体特性促进硫化锌精矿中低价硫化物的高效溶解,同时实现铁酸锌、金属硫化物的强化解离和铁的高效沉淀分离。研究结果表明:添加锌浸出渣可以强化硫化锌精矿的浸出;反应温度和初始酸度是关键影响因素,升高反应温度可显著提高锌浸出率,同时促进Fe3+水解沉淀成铁矾,提高酸度可以促进硫化锌精矿的高效溶解,但酸度过高时氧气溶解度降低,将抑制硫化锌精矿的溶解和Fe3+水解沉淀。在锌浸出渣与硫化锌精矿质量比为1:3、初始酸度95 g/L、反应温度160℃、液固比7:1、氧压0.8 MPa、搅拌转速800 r/min、反应时间120 min的最优技术条件下,渣计锌浸出率为98.6%,同时溶液中92.69%的铁以铁矾的形式沉淀入渣,浸出终渣主要物相组成为单质硫、黄钾铁矾、黄钠铁矾和赤铁矿,其占比分别为40.00%、39.10%、16.60%和4.30%;浸出液中铁质量浓度仅为1.62 g/L,为浸出液后续提锌创造了有利条件。

In view of the industrial technical problems such as high energy consumption of two-stage oxygen pressure leaching of zinc sulfide concentrate and large amount of hazardous waste iron slag from zinc leaching slag treatment, a synergistic leaching process of zinc sulfide concentrate and zinc leaching slag was proposed. The oxygen carrier properties of medium and high valent iron promote the efficient dissolution of low-valent sulfides in zinc sulfide concentrates, and the dissociation of zinc ferrite and metal sulfides and the efficient precipitation and separation of iron were enhanced. The results show that adding zinc leaching residue can strengthen the leaching of zinc sulfide concentrate. The reaction temperature and initial acidity are the key influencing factors.Increasing the reaction temperature can significantly improve the zinc leaching rate and promote the hydrolysis and precipitation of Fe3+into alum. Increasing the acidity can promote the efficient dissolution of zinc sulfide concentrate. However, when the acidity is too high, the oxygen solubility decreases, which will inhibit the dissolution of zinc sulfide concentrate and the hydrolysis and precipitation of Fe3+. The optimal technology is that the mass ratio of zinc leaching residue to zinc sulfide concentrate is 1:3, the initial acidity is 95 g/L, the reaction temperature is 160 ℃, the liquid-solid ratio is 7:1, the oxygen pressure is 0.8 MPa, the stirring speed is 800 r/min,and the reaction time is 120 min. Under the conditions, the leaching rate of zinc from the slag is 98.60%, and 92.69% of the iron in leachate is precipitated into the slag in the form of jarosite. The main phase composition of the final leaching slag is elemental sulfur, jarosite, jarosite, hematite, whose proportions are 40.00%, 39.10%,16.60% and 4.30%, respectively. The iron concentration in the leaching solution is only 1.62 g/L, which creates favorable conditions for the subsequent extraction of zinc from the leaching solution.