| Smelting acid sludge is one of the main wastes in the process of smelting copper and zinc by pyrotechnics,in the nonferrous metallurgy industry,especially in China,there are many problems such as large consumption of resources,high energy consumption for production,low utilization rate of secondary resources,and a considerable part of available secondary resources that pollute the environment because they are not used.At present,the problem of environmental pollution has become very serious.If the metals in the smelt sludge are effectively recycled,it will be beneficial to make full use of secondary mineral resources,save energy and reduce consumption,reduce environmental pollution,and have obvious social,economic and environmental benefits.In this paper,the smelting acid sludge produced by a zinc smelter in a city was recovered,and the copper and zinc elements in the sludge were extracted and recovered.The test results are as follows:(1)The effects of sulfuric acid concentration,solid-liquid ratio,leaching time and leaching temperature on the leaching rates of copper,zinc,iron and arsenic were investigated by leaching experiments with sulfuric acid on the sludge,and the results showed that the maximum leaching rate could be reached under the conditions of sulfuric acid concentration of 2 mol/L,solid-liquid ratio of 1:6,leaching time of 2 h and temperature of 60 ~oC.Under the above optimal conditions,the leaching rates of copper,zinc,iron and arsenic reached 90.65%,95.26%,79.32%and 85.45%,respectively.Under the optimal leaching conditions,the concentrations of copper,zinc,iron and arsenic in the leaching solution were 1.51 g/L,2.45g/L,3.21 g/L and 5.48 mg/L,respectively.(2)Arsenic removal tests were carried out by lime-iron salt method to investigate the effects of iron-arsenic ratio,temperature,end-point p H value and time on the arsenic removal rate.It was concluded that when Fe/As(molar ratio)=1:1,water bath temperature 85 ~oC,and the end-point p H of the reaction was controlled at 1.2 and the reaction time was 5 h,the removal rate of arsenic was 72.22%.(3)The effect of excess coefficient of iron powder,temperature,p H value and reaction time on copper replacement rate was investigated through copper recovery test by replacement method.It was concluded that when the replacement temperature was 60 ~oC,the leaching solution p H 2,the reaction time was 2 h,and the excess coefficient of iron powder was 1.5 times,the optimal replacement rate was achieved,and the replacement rate reached99.63%.(4)Iron removal test was carried out by oxidation neutralization method,and the effects of hydrogen peroxide dosage,reaction time,temperature and initial p H on iron removal rate were investigated.It was concluded that when the reaction time was 2 h,the reaction temperature was 60 ~oC,the initial p H of the solution was 2.0,and the amount of hydrogen peroxide was 2.5 m L,the iron removal rate reached 99.79%.(5)By solvent extraction of zinc recovery test,initial p H value,P204 volume concentration,extraction time,extraction(O/A)influence on extraction rate,concluded that when the initial solution p H value is 3.5,P204 volume concentration is 30%,the extraction time of 6 min,extraction(O/A)is 2:1,extraction temperature is 70 ~oC when the zinc in the best single stage extraction rate can reach 58.6%,after 4 extraction of zinc extraction rate of98.33%,reverse extraction rate of 99.15%,basic can completely reverse extraction. |
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