Removal Of Thallium From Lead Sulfide Concentrate By Microwave-oxidation-acid Leaching Process

Tantalum is a toxic element with extremely strong physiological toxicity.The lead sulfide concentrate contains higher Tl.Through human activities and epigenetic effects,Tantalum can be relocated to the environment,and threat the ecological environment.In this paper,it is proposed that the process of "microwave-oxidation-acid leaching" can effectively reduce the content of Tl in lead sulfide concentrate and control the pollution of Tl from the source.The tested sample in this paper was obtained from Hunan Baoshan non-ferrous metals industry Ltd,the grade of thallium is 38.34 g/t.Thallium removal from lead sulfide concentrate was achieved by microwave-oxidation-acid technique.The stable situation of rising temperature was investigated for the lead concentrate and sulfuric acid solution in microwave field.IBMM shows that Tl exists in the lead sulfide concentrate with the form of reductant,and oxidizing reaction is belificial to the removal of Tl from the sample.The effect of different oxidants and oxidant dosage on Tl removal efficiency from lead sulfide concentrate under microwave heating was investigated.The effect of rotated speed,grinding fineness,sulfuric acid dosage,liquid to solid ratio and leaching temperature on Tl removal efficiency were studied.The effect of extraction concentration,extraction time,the oil to aqueous ritio,extraction temperature and reverse extraction on Tl extraction were investigated.(1)The situation of rising temperature was stable for the lead sulfide and sulfuric acid solution in microwave field,and there was no overheating.(2)In the microwave-oxidation-acid leaching process,H2O2,KMnO4,and NaClO were selected as oxidants.Under the same conditions,when using NaClO as an oxidant under microwave heating conditions,the removal rate of Tl was the highest.Compared with conventional water heating and microwave heating,using NaCIO as an oxidant,the effect of rotated speed,grinding fineness,sulfuric acid dosage,liquid to solid ratio and leaching temperature on Tl removal efficiency were studied.It shows the removal rate of Tl was the highest in microwave heating conditions,and the removal rate of Tl reached more than 80%.The best experimental conditions:rotated speed 300 r/min,grinding fineness-0.074 mm 90%,sulfuric acid dosage of 7%,liquid solid ratio 3:1,leaching temperature o 90 ?;Repeating test results:the removal rate of Tl was 80.98%.Using the unreacted nuclear contraction model to fit Tl leaching data,the activation energy of Tl leaching under microwave heating was 40.92 kJ/mol,and the activation energy of Tl leaching under normal water bath heating was 18.11 kJ/mol.(3)After microwave leaching,the leachate is pretreated to obtain the original leachate,Extraction and reverse extraction tests of the extract solution were conducted.The effect of extraction concentration,extraction the oil to aqueous ritio,extraction time,extraction temperature,and reverse extraction the oil to aqueous ritio were investigated.The best experimental conditions:extraction concentration 25%,extraction time 6 min,extraction the oil to aqueous ritio 3:1,extraction temperature 30 ?,reverse extraction the oil to aqueous ritio 3:1,The TI extraction rate was more than 96%,and the reverse extraction rate was more than 95%...