Technology For Leaching Tellurium From The Gold Concentrate Containing Tellurium Cyanide Tailings

There are a large amount of the gold concentrate containing tellurium in the lesser Qinling Mountains area of Henan Province.For the disposal of such ores are mainly through cyanide leaching to recover gold and silver from the gold concentration which is obtained by flotation and enrichment at present.So,plenty of the gold concentrate containing tellurium cyanide tailings are produced.However,this type of ore contains high gade metal tellurium.The storage or landfill of these tailings will cause great damage to the environment and waste tellurium resources.Therefore,the development of a process for leaching tellurium form such ore will be of great value.This study based on process mineralogy adopted the oxidation roasting-alkaline leaching process to leaching tellurium from gold concentrate containing tellurium cyanide tailings Meanwhile,started study separately for the oxidizing roasting-alkali leaching and roasting kinetics of leaching process for the main tellurides in this type of ore-PbTe,and explore the mechanism of alkali leaching of PbTe and construct the roasting kinetic model of PbTeIn the study of process mineralogy,it is found that the elemental tellurium in ore mainly exists in the minerals of altaite(PbTe),tellurobismuthite(Bi2Te3),frohbergite(FeTe2)and grilnlingite(Bi2TeS2),and the grade of tellurium reaches 161 g/t.Among them,tellurium is mainly distributed in PbTe with a ratio of 63.77%.The particle size of the tellurium-containing minerals is fine,both below 18?m,and the particle sizes of the FeTe2 and Bi2TeS2 ore are finer,all below 4.8 ?m.Each of the tellurides has been substantially dissociated from the monomer without further grinding.On this basis,The cyanide tailings was directly leaching under the process conditions of NaOH adjusting pulp pH 13,Na2S dosage 17.5 g/L,leaching temperature 80?,leaching time 5 h,pulp solid ratio 4:1,the leaching rate of tellurium is only 43.72%,the leaching rate is low.Then,combined with the nature of the telluride,adopted a new process for leaching tellurium by oxidizing roasting-alkali leaching.The roasting temperature was 5300C,the roasting time was 2h,the pH of the pulp was adjusted to 12 by NaOH,the amount of NaZS was 15 g/L,leaching temperature 80?,leaching time 5h,pulp solid ratio 4:1,the leaching rate of tellurium was 68.38%.Compared with the direct alkali leaching process,the consumption of chemicals is reduced,the leaching time is also reduced,and the leaching rate of tellurium is increased by 24.66%.The leaching effect of the oxidizing roasting-alkali leaching process is obviously better than that of the direct alkali leaching process,It is better to achieve leaching of cesium from such ores.It was found that oxidizing roasting is necessary before alkali leaching and Na2S is indispensable in the process of alkali leaching from the test of alkali leaching of PbTe.The use of Na2S not only achieves the separation of Te and Pb,but also avoids the formation of PbTeO3,which can greatly improve the leaching rate of tellurium.During the oxidative roasting test of PbTe,I found that too high roasting temperature caused a large amount of PbTeO3 to be encapsulated on the surface of PbTe,which reduced the rate of PbTe oxidation,and prevented further reaction of PbTe.In addition,the chemical reaction kinetics study on the oxidative roasting of PbTe shows that the PbTe conforms to the random nucleation and subsequent growth model during oxidative roasting.The function expression is:[-ln(1-a)]2=17.3136B-2.4028exp(-67690/RT)t.Its apparent activation energy E was 67.69 kJ/mol.