Study On Cleaning Extraction Technology Of Antimony Sulfide Concentrate By Reduction And Sulfur-fixing Roasting

The metal antimony is an important strategic resource,60%of the world's antimony resources are concentrated in China.At present,the main process is pyrometallurgy,and there are problems such as long process,high energy consumption and low concentration of SO₂pollution.And the hydrometallurgy process has problems such as waste water,extraction efficiency and equipment corrosion.It is urgent to develop a green and economical method of antimony smelting.Therefore,a new extraction process of antimony sulfide concentrate based on reduction sulphur-fixation roasting was proposed.Taking ZnO as sulfur-fixing agent and carbon as reducing agent,the metal antimony was directly obtained by roasting Sb₂S₃at low temperature.Subsequently,antimony was separated by mineral processing and SO₂was not produced in the process.Firstly,the thermodynamic analysis of Sb₂S₃-ZnO-C system was carried out.The dominant zone diagram of Sb-S-O and Sb-Zn-S-O systems showed that Sb₂S₃could be directly converted to metallic antimony,and with the increase of temperature,the requirements of oxygen and sulfur partial pressure for the coexistence stability zone of Sb and Zn S were reduced.The?r G^?values of all the other reactions were less than zero temperature range 500–1000?,which indicated that the reductions of Sb₂S₃were spontaneous.In addition,according to the equilibrium simulation analysis of Sb₂S₃-ZnO-C system,it could be concluded that reactions may be carried out in two steps without SO₂generated.Secondly,the dynamic reactions were performed.The kinetics Sb₂S₃-ZnO system and Sb₂S₃-ZnO-C system were calculated based on TG-DSC,results showed that in the Sb₂S₃-ZnO system,the average values of E and ln A of the reaction between Sb₂S₃and ZnO were 189.72 k J/mol and 35.29 s^-1,respectively.In the Sb₂S₃-ZnO-C system,the E values in sulfur-fixing reaction and reduction reaction were 233.4 k J/mol and 288.59 k J/mol,and ln A was 41.92 s^-1and 40.7 s^-1,respectively.The XRD and SEM analysis of the products indicated that the roasting reaction could be divided into two steps,The first step was the cross-reaction between Sb₂S₃and ZnO to obtain Sb₂O₃and Zn S,and the second step was the reduction of Sb₂O₃to Sb over 700?.Zn S and Sb did not form a package,which was conducive to the separation of Sb and Zn S in the subsequent process.It was also clear that the metal antimony was made up of larger microcrystals,and a reduced cooling mode was beneficial to make surface of Sb particles smooth.Finally,the roasting process was optimized and the optimal reaction conditions were as follows:roasting temperature of 800?,carbon powder size of100–150 mesh,content of ZnO 1 times the stoichiometric requirement,and roasting time of 2 h.Under the optimal condition,the antimony generation rate and the sulfur-fixing rate could reach 90.4%and 94.8%,respectively.In the comprehensive expansion experiment,Sb₂S₃concentrate with high and low antimony content was used,the formation rate of Sb was 91.8%,88.9%,and the sulfur fixation rate was 89.1%,86.1%,respectively.The direct recovery rates of Sb and Zn were 90.57%and 89.23%,and the gold enrichment rate and sulfur fixation rate were 87.82%and 94.35%,respectively.Therefore,the feasibility of the process was verified.It can be concluded that this new process is short,low temperature,low consumption and has an increased economic attraction to the extraction similar heavy metal sulfide.