Pressurized leaching and phase evolution behavior of copper smelting dust
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(FeAsO4·nH2O,n≠2)to crystalline iron arsenate(FeAsO4·2H2O).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.
copper smelting dustpressure leachingzinc and copper leaching ratescorodite
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