Research On The Comprehensive Recovery Of Valuable Metals From Zinc Kiln Slag Processing And Smelting

With the rapid development of economy,the production and consumption of non-ferrous metals in China have reached record highs in recent years,resulting in the increasingly serious problem of smelting waste slag treatment.Zinc kiln slag as one of the waste slags produced by the zinc smelting process that contains more valence metal components,but its resource utilization has always been a big problem.The research object of the zinc kiln slag was produced by a zinc smelter in Yunnan province to conduct a comprehensive recovery process for valuable metals in this paper.The element composition,phase composition and occurrence state of raw materials are analyzed by modern analytical methods?XRD?XRF?SEM?ICP?and based on the analysis that it was confirmed that the main recovery elements were C,Fe,Cu,Zn,In and the possibility of comprehensive recovery was verified by the selective metallurgical process experiments,including carbon flotation,magnetic separation,and leaching experiments.The results are as shows:?1?The appearance of this zinc kiln slag is reddish brown with high hardness.The mineral composition is complex that the largest component is the iron compound with an elemental content of 36.21%while phase composition is triiron tetroxide,elemental iron,iron oxide and iron sulfide.Other valuable elements include 1.02%copper,2.24%zinc,94.78g/t indium,46.64g/t silver while the majority of the phases are sulfides.?2?The results of carbon flotation and magnetic separation experiments are all poo r as the main elements Cu,Zn,and In are unevenly distributed that not conducive to not conducive to the purpose of this study in exploratory experiment.?3?The influence of oxidant concentration,sulfuric acid concentration and reaction temperature on the leaching rate of each element was examined in leaching experiment of kiln slag under normal pressure oxidation.The optimal technological conditions are as follow:the zinc kiln slag was leached at 80?for 2h with sulfuric acid concentration3mol·L^-11 as H₂O₂ oxidant addition 0.6m L·g^-1 in liquid-solid ratio 6:1.Under this conditions that the leaching rate of indium is 93.92%while the leaching rate of copper is 89.84%as well as the leaching rate of zinc is 66.49%.On basis of this experiments,response surface methodology was used to optimize the indium leaching rate while the model fit was better.The optimized technological parameters are as fllows:the zinc kiln slag was leached 80.51?for 2h with sulfuric acid concentration 2.92mol·L^-1 as H₂O₂oxidant addition 0.6m L·g^-1 in liquid-solid ratio 6:1.under this conditions the leaching rate of indium is 91.57%.?4?The influence of particle size,sulfuric acid concentration and leaching temperature on the leaching rate of each element was examined in this leaching experiment of kiln slag under oxygen pressure oxidation.The optimal technological conditions are as follow:the zinc kiln slag with particle size at 75%-0.048mm was leached at 160?for 1.5h that sulfuric acid concentration at 2mol·L^-1 as sodium lingo sulfonate added in an amount of 1%in liquid-solid ratio 7:1 under oxygen partial pressure 1.0MPa.Under this conditions that the leaching rate of indium is 93.85%while the leaching rate of copper is 93.98%as well as the leaching rate of zinc is 91.11%.On basis of oxygen pressure leaching process parameters,a kilogram-scale expansion test was conducted that the test results were good.The obtained leaching rate result that laeching rate of indium is 90.41%as leaching rate of copper is 91.83%as leaching rate of zinc is 89.57%while more consistent with the small experimental results.