Research On Alkali Leaching Of High Arsenic Fumes From Copper Smelting And Treatment Of The Leaching Solution

Arsenic is widely found in the earth's crust and is usually associated with metal minerals.As the main mineral is mined,most of it goes into the smelting system.Further,various arsenic-containing materials are formed during the smelting process.At present,more than 80%of the world's copper is produced by pyrometallurgical smelting.In the pyrometallurgical process using raw copper concentrate as raw material,it will produce about 10%of the fine copper production.In addition to a large amount of valuable metals such as copper,lead,zinc,antimony,bismuth and indium,soot also contains a large amount of arsenic.Once improperly handled,it is easy to cause environmental pollution,which has a serious negative impact on social development.Taking copper smelting high arsenic soot as the research object,based on the principle of“effective separation of arsenic and valuable metals to effectively recover valuable metals and arsenic centralized treatment”,to achieve comprehensive utilization of resources and reduce environmental pollution.Based on a large number of literatures,this study proposed the process of“alkali leaching–sulfide precipitation–arsenic precipitation”and carried out theoretical and experimental research on its main processes.It mainly includes the following contents:1.Chemical composition analysis,chemical phase analysis,X-ray diffraction analysis,scanning electron microscopy and energy spectrum analysis were us ed to study the high arsenic fumes in copper smelting.The results show that the main elements contained in soot are As,Zn,Pb and Bi.Among them,Zn and Pb mainly exist in the form of oxides and sulfates,and As mainly exists in the form of oxides,sulfa tes and arsenates.Pb,Zn and As are mutually doped and uniformly distributed.2.The thermodynamics of the high arsenic soot pickling process in copper smelting was studied by using the Meh-H₂O Eh-pH diagram under 298K conditions.The results show that alkali leaching of arsenic from copper smelting soot is thermodynamically feasible.During the alkali leaching process,the process pH is controlled,As will enter the solution,and Zn,Pb,and Bi enter the leaching slag.Conducive to centralized disposal of arsenic and comprehensive recovery of valuable metals.3.The conditional test was used to test the alkali leaching process of high arsenic soot in copper smelting.The optimization conditions are:NaOH concentration 3.81M,leaching temperature 80?,leaching time 120 minutes,liquid-solid ratio 4:1,stirring speed 450 r/min.Under the optimal conditions,the leaching rate of As is 96.02%,the leaching rate of Zn is 9.58%,and the leaching rate of Pb is 17.54%.4.The condition test was used to conduct the sulfide precipitation test on the alkali immersion liquid.The optimization conditions are:1.5 times the amount of Na₂S added,the temperature is 70?,and the time is 60 minutes.Under optimized conditions,the lead and zinc recovery rates were:>92%and 98%,respectively.5.The arsenic test was carried out on the sulfided precipitated liquid by conditional experiment.The optimum conditions were as follows:the molar ratio of calcium to arsenic was 9,the test temperature was 65?,the test time was 2 h,and the amount of aluminum chloride added was 0.075 mol.Under optimized conditions,the solidification rate of arsenic reached 98.99%.