The Selective Bioleaching Of Zinc From Lead-sulfate Concentrate And Its Leaching Mechanism

In this paper,due to the close symbiosis of lead-zinc ores,the high zinc content of the lead concentrate produced by traditional flotation,there are technical difficulties or high costs in further separation.Taking the high zinc lead concentrate as the research object,the screening and domestication of the bioleaching bacteria,the influencing factors of the selective zinc leaching process,and the mechanism are discussed and studied.In order to selectively leach the zinc from the lead concentrate by means of bioleaching technology,to reduce the zinc content of the lead concentrate and effectively enrich the valuable metal zinc,to remove the impurity zinc from the lead concentrate,to improve the comprehensive recovery rate of the lead and zinc,and to indirectly solve the problem of complex lead and zinc ore dressing.It provides a new technical idea and technology,which has far-reaching theoretical significance and practical application value.The effects of insoluble lead salt(PbSO4)and Zn2+on the bacteria were simulated,and the bacteria were screened and domesticated.The physiological activity of bacteria was not affected by the trace amount of Pb2+released from PbSO4 during bioleaching of zinc bearing lead concentrate.Zn2+ is the main toxic ion in the bioleaching process of zinc lead concentrate.Mesophilic bacteria have better tolerance to Zn2+than mesophilic bacteria.After 7 days of bioleaching,the formation rate of lead alum in mesophilic bacteria system is 34.57%;that in mesophilic bacteria system is 44.93%;the bioleaching process of mesophilic bacteria produces less lead alum,and the zinc leaching selectivity is better.The medium temperature bacteria and different domestication materials were used to domesticate the high-efficiency ore leaching bacteria,and the zinc concentrate domestication bacteria was obtained as the experimental strain.The high-throughput technology was used to explore the change rule of the bacterial structure during the zinc leaching process.In the early stage of leaching,the dominant bacteria and its content were Acidithiobacillus sp.(59.15%).In the middle stage of leaching,the dominant bacteria was Sulfobacillus sp.(54.8%),and in the later stage of leaching,the dominant bacteria was Sulfobacillus sp.(66.87%).This paper reveals the law of bioselective zinc leaching of zinc bearing lead concentrate,and investigates the influence of pulp concentration,pulp pH value,leaching time,C(Fe3+)/C(Fe2+)and other factors on the leaching results.The lower pulp concentration is more favorable for the selective zinc leaching of zinc bearing lead concentrate.When the initial pH value is 1.8,the leaching system shows the maximum zinc leaching rate of 55.33%,the minimum lead alum formation rate of 31.12%,and the lead grade of 58.32%.When the ratio of C(Fe3+)/C(Fe2+)is high,it is beneficial to the oxidation process of bioleaching.When the ratio of C(Fe3+)/C(Fe2+)is 1:1(TFe 3g/L),the selectivity of zinc leaching from zinc bearing lead concentrate is the best,the zinc leaching rate is 63.12%,the lead alum production rate is 28.7%,the grade of Pb is 58.97%,and the content of impurity Zn decreased to 3.31%.With the increase of leaching time,the growth rate of lead alum decreases,and the longer leaching time is conducive to the selective leaching of zinc in zinc bearing lead concentrate.According to the influence rule of bioleaching conditions,the better process conditions are to control the pulp concentration within 8%,the initial pH value is 1.8,the C(Fe3+)/C(Fe2+)is 1:1(TFe 3g/L),and the leaching time is 7 days.The relationship between the shrinking core model controlled by kinetic diffusion and the factors such as temperature,particle size,pH value and pulp concentration on the oxidation rate of ZnS and PBS in bioleaching system was studied.Combined with various characterization techniques,the mechanism of selective bioleaching of zinc bearing lead concentrate was analyzed,the oxidative etching effect of bioleaching bacteria on the particles of zinc bearing lead concentrate was explored,the types,binding energy and valence of various elements in the product layer were found out,and the complex redox reaction mechanism and diffusion control steps in bioleaching of zinc bearing lead concentrate were revealed.These preliminary results provide a theoretical basis for the practical application of selective bioleaching of zinc bearing lead concentrate.