Research On The Resource Treatment Of High Arsenic And Antimony Dust By The Selective Oxidation-reduction Two-step Method

At present,the accumulation of arsenic-antimony dust generated in the smelting process of non-ferrous metals is large,and them was piled and stored in most enterprises,which not only causes great waste of resources,but also poses a great threat to the environment and human health.Thus,it is very necessary to study the resource and harmless treatment of arsenic-antimony dust.For this situation,this paper carried out a study on the selective oxidation roasting of arsenic-antimony dust using Ca O as an additive to separate arsenic and antimony,and combined with the reduction roasting-carbon-thermal reduction process in a closed pot to recover arsenic.Based on the difference in oxidizability and volatility between As₂O₃ and Sb₂O₃,a facile method for promoting the separation of arsenic and antimony through destructing arsenic-antimony solid solution structure from the dust using Ca O in an oxidizing atmosphere was adopted in this study,and the effects of the variables,including addition amount of Ca O,roasting temperature and time,oxygen partial pressure on the volatilization of arsenic and antimony were investigated.The results show that the formation of the vitreous material?As-Sb-O?was hindered through the transformation of Sb₂O₃ and?Sb,As?₂O₃ in the untreated dust into Sb₂O₄,Sb₂O₅,Sb₆O₁₃ and Ca₂Sb₂O₇,and the volatilization of arsenic was promoted,under an oxidizing atmosphere in the presence of Ca O.The volatilization of arsenic of 91.53%was attained,while the volatilization of antimony was only 4.30%when the conditions of 5 wt.%Ca O,a roasting temperature of 550°C,an oxygen partial pressure of 21vol%,and a roasting time of 80 min,and antimony in the slag was recovered in the form of antimony concentrate,and arsenic was mainly condensed and collected in the form of As₂O₃,which realized the efficient separation of arsenic and antimony.A study for obtaining primary As₂O₃ by using Pb O and activated carbon as additives to separate antimony and other impurities from high arsenic volatiles by reduction roasting was conducted.Under the conditions of Pb O addition amount of 12%,activated carbon amount of 20%,roasting temperature of 550 ^oC and roasting time of30 min,97.01%arsenic was separated by volatilization and recovered as primary As₂O₃,while 79.01%antimony was fixed in the residue in the form of Fe Sb₂,Sn Sb and Pb-Sb alloy.This method achieved effective separation of arsenic and impurities such as antimony in high-arsenic volatiles.Finally,the primary As₂O₃ was used as the raw material for the production of elemental arsenic,and the As_98.5 elemental arsenic with a purity greater than 98.5%and the As_99.0 elemental arsenic with a purity higher than 99.0%were obtained through the carbon thermal reduction of the closed pot,thus the resource recovery of arsenic was achieved.