铜冶炼烟尘加压浸出及物相演变行为

Pressurized leaching and phase evolution behavior of copper smelting dust

铜冶炼烟尘是火法炼铜过程产出的高附加值二次资源,为实现其中铜、锌等有价金属的浸出及砷的分离,本文研究铜烟尘加压浸出及同步沉砷新工艺技术参数优化与过程物相演变规律。结果表明:在反应温度由140℃升高至160℃过程中,锌、铜浸出率分别可达96%和97%,砷沉淀率由36%提高至92%,砷沉淀形态由非晶形砷酸铁(FeAsO_(4)·n H_(2)O,n≠2)向晶型砷酸铁(FeAsO_(4)·2H_(2)O)演变;整个反应过程显著分为以锌、铜高效浸出(0~60 min)和砷铁共沉淀(60~180 min)两个阶段;增大搅拌转速、提高液固比可进一步提升体系的氧化传质速率和砷酸铁矿化物相-臭葱石生成速率。在反应温度160℃、时间3 h、初始酸度40 g/L、液固比5∶1、搅拌转速600 r/min的优化技术参数条件下,锌、铜浸出率均可达96%以上,砷沉淀率可达92%,浸出渣主要物相为硫酸铅与臭葱石,实现了锌、铜的深度浸出和砷的高效分离。

Copper smelting dust is a high value-added secondary resource produced in the process of copper smelting.In order to realize the deep leaching of valuable metals,such as copper and zinc,and the efficient separation of arsenic,this paper carried out the optimization of the technical parameters of the new process of pressurized leaching of copper dust and synchronous deposition of arsenic and studied the law of phase evolution of the process.The results show that,when the reaction temperature increases from 140℃ to 160℃,the leaching rates of zinc and copper reaches 96%and 97%,the precipitation rate of arsenic increase from 36% to 92%,and the precipitation form of arsenic changed from amorphous iron arsenate(FeAsO_(4)·n H_(2)O,n≠2) to crystalline iron arsenate(FeAsO_(4)·2H_(2)O).The whole reaction process is significantly divided into two stages characterized by high efficiency leaching of copper,zinc and arsenic(0-60 min) and coprecipitation of arsenic and iron(60-180 min).Increasing the stirring speed and liquid-solid ratio can further improve the oxidation mass transfer rate and the formation rate of iron arsenate mineral-scalloite phase.Under the optimized technical parameters of reaction temperature 160℃,reaction time 3 h,initial sulfuric acid concentration 40 g/L,slurry liquid-solid ratio 5∶1 and stirring speed 600 r/min,the leaching rates of zinc and copper can reach more than 96%,and the precipitation rate of arsenic can reach 92%.The main phases of leaching residue are lead sulfate and scorodite.Deep leaching of zinc and copper and high efficiency separation of arsenic were realized.