Study On The Purification Of Antimony-enriched Gold By Electrowinning Crude Antimony Vacuum Distillation

Antimony-gold concentrate is an important antimony and gold resource.Electrowinning crude antimony containing gold will be produced by sodium sulfide leaching-sodium thioantimonite solution electrowinning process.The electrowinning crude antimony is directly sold,and the value of antimony and gold is greatly lost.However,it is difficult to separate antimony and gold by the widely used alkaline pyrometallurgical refining process,and the refining slag yield is large and the refining efficiency is low.Therefore,it is of great practical significance to develop a technology for the efficient separation and purification of antimony and gold enrichment of electrowinning crude antimony.Aiming at the typical electrowinning crude antimony produced by a domestic gold production enterprise(about 70?80%antimony,about100 g/t gold),the research group proposed a refining process with vacuum distillation as the core,which realized the purification of antimony and enrichment of gold cleanly and efficiently.Firstly,by means of X-ray fluorescence spectroscopy,chemical analysis,ICP-AES and X-ray diffraction,the chemical composition and the occurrence state of the main impurities in the electrowinning crude antimony were determined.The results show that the main impurity elements of electrowinning crude antimony are sodium,sulfur,iron,arsenic,selenium and copper,and the gold content is up to 100 g/t.The sodium and sulfur are physically mixed in the crude antimony in the form of Na Sb(OH)₆,Na₂S_x,Na₂SO₄ and Na₆(CO₃)_x(SO₄)_y.Secondly,the theory,small-scale experiment and ten-kilogram scale expansion test of electrowinning crude antimony vacuum distillation to purify antimony-enriched gold were carried out.The feasibility of electrowinning crude antimony vacuum distillation to purify antimony-enriched gold was discussed,and the optimal distillation conditions were obtained.The distribution of main impurities in the vacuum distillation process and the technical indexes could be achieved were defined.Studies have shown that the electrowinning crude antimony can achieve antimony purification and gold enrichment through vacuum distillation.Under the optimal conditions of distillation temperature 1073 K,holding time 30 min,and pressure 10?30 Pa,the content of antimony and gold in the volatiles is 99.79%and 0.92 g/t,the volatilization rate of antimony and gold is 90.49%and 0.66%,and Sb₂O₄,Na₂Sb₄O₇ and other non-volatile antimony compounds are the main reason for the low antimony volatilization rate.Sodium salt hinders the evaporation of antimony.The antimony volatilizes basically meets the requirements of the national standard,and sodium salt and arsenic are the main impurities that affect the purity.Gold is enriched in the residue together with selenium,iron,and copper,and gold can be enriched by about 11 times.Thirdly,the method of electrowinning crude antimony melting and slag removal to remove sodium salt was proposed.Corresponding theories,small-scale experiments and expanded experimental research were carried out to investigate the influence of crucible material,melting temperature,holding time,and atmosphere on the distribution of antimony and gold in the scum.Studies have shown that the density of Na₂SO₄,Na Sb O₃ and other sodium salts in the electrowinning crude antimony is less than that of antimony and gold.The sodium salt can be effectively removed by melting and slagging.With the increase of melting temperature and the extension of holding time,the distribution of antimony in the scum tends to be stable,and the distribution of gold in the scum tends to decrease.The main phase of the scum changes with the melting temperature,and the phase of the crucible is different for different materials.In the air atmosphere,electrowinning crude antimony melting and sodium removal should be carried out at a higher temperature,but there is obvious oxidation of antimony in the process of melting,slagging and cooling.Finally,an expanded test study of 100 kg vacuum distillation was carried out to investigate the influence of the removal of sodium salt on vacuum distillation.The results show that the removal of sodium salt has a significant effect on improving the purity of volatiles and the evaporation rate of antimony.The Na₃Sb S₄·9H₂O remaining in the antimony liquid can volatilize together with the antimony.On the basis of the existing experiments,the process of"electrowinning crude antimony melting to remove sodium salt-vacuum distillation enrichment of gold-remelting refining to remove arsenic"was determined to purify antimony and enrich gold.The direct yield of antimony and gold in the whole process was about 94%and96%,and the power consumption of crude antimony per ton was about 2000k W·h.The economic and social benefits were significant after the application in the future.