Selective Oxidation-sulfide Roasting Arsenic And Antimony Fumes To Separate Arsenic And Recovery Of Antimony Resources

In China,under the serious arsenic pollution and exhausted antimony resources,it is important to improve the smelting technology level and efficiency.In addition,the recovery of arsenic and antimony should be regarded as a strategy of nonferrous metallurgy development.The arsenic-antimony bearing dust are mostly produced in the process of recovering precious metals from nonferrous metal anode slime in central and southwest China.The Sb content of the dust is 20⁵0%and As is 20⁴0%.Arsenic-antimony bearing dusts contains large amounts of harmful elements arsenic,the directly stacked will pose a potential threat to the environment.Meanwhile,and the content of antimony resources,find an appropriate method for separating the arsenic and antimony is the best way to weaken the environmental hazards and relieve the crisis of antimony resources.Considering that the Sb₂O₃ is more easily oxidized and vulcanized than As₂O₃,this study proposes a way to separate the arsenic from dusts by selective oxidation-sulfurization roasting using CuO and CuS,and the way of recovering antimony resources after removing arsenic is also put forward.The XRD and EPMA analysis show that The arsenic and antimony in arsenic-antimony bearing dusts exist mainly in the forms of As₂O₃ and Sb₂O₃,respectively,and accompanied by a small amount of?Sb,As?₂O₃.The addition of CuO play an active role on separation of arsenic and antimony.The results show that volatilization rates of arsenic and antimony increase with the roasting temperature and time.The structures of?Sb,As?₂O₃ in the dust will be destroyed after the“Sb”component being oxidized to Sb₂O₄ that stayed in the roasted residue,and this part of arsenic is released to volatilize.However,in a certain range,the arsenic volatilization rate decreases with CuO amount which is attributed to the more formation of Cu₃?As O₄?₂ and Cu₃As.Under the optimum conditions of roasting temperature of 400°C,roasting time of 100 min,CuO amount of34.54%and N₂ flow rate of 30 m L/min,the antimony in dusts is transformed into Sb₂O₄and its volatilization rate is only 8.63 mass%.Meanwhile,the arsenic removal rate is up to 91.50 mass%,and the arsenic content in the roasted residue is reduced to 1.08%.In order to further reduce the arsenic content in the roasted residue,simultaneously combined with the low volatility of stibnite at low temperature,CuO was chosen as an additive to treat the arsenic-antimony bearing dust with a comprehensive oxidation and sulfidation roasting tests.The experimental results show that a better separation rate of arsenic and antimony can be obtained using CuS,the reason mainly includes two points.In the one hand,the structures of?Sb,As?₂O₃ in the dust will be destroyed by the suitable oxidizability of“Cu2+”in CuS,in which the“Sb”component being tramsformed to Sb₂O₄ and Sb₂S₃ that stayed in the roasted residue and arsenic is released to volatilize.In the other hand,the sulfurization of is Sb₂O₃ poper to As₂O₃,causing the easier tramsformation of“Sb”component to the nonvolatile Sb₂S₃.Therefore,Under the optimum conditions of roasting temperature of 400°C and CuS amount of 130%,the volatilization rates of arsenic and antimony are 97.80%and 8.29%,respectively,and the arsenic content in the roasted residue is reduced to 0.3%.Finally,CO is used as a reducing agent to recovery antimony in the roasted residue.The results show that recovery rate of antimony increases with temperature from 650 to800°C,and decreases with temperature increased further due to the formation of metallic antimony.Similarly,the recovery rate of antimony increases substantially with the CO partial pressure range of 1.25 to 7.5 vol%,and then decreases gradually when the CO partial pressure is over 7.5 vol%.Under optimized conditions of roasting temperature of 800°C,CO partial pressure of 7.5 vol%and roasting time of 120 min,98.40%of arsenic removal rate and 80.40%antimony recovery rate could be obtained.In addition,the products of“As₂O₃”can be used for preparing ferric arsenate after it has been oxidated which realized the harmless treatment of it.