Research On Technology Of Comprehensive Recovery Of Antimony In Black Copper Sludges

At present, the researches of treatment of black copper sludges mainlyfocuse on controlling arsenic contamination,essentially recycle copper andarsenic or recycle arsenic only. Because antimony products have highervalue and better market prospect, it will cause waste of antimony resource.In this paper, two process routes was designed to recycle copper and arsenicas well as recycle antimony. The first process route is: black copper sludgeswere leached in sulfuric acid solution firstly, Leaching residue was leachedin the sodium sulfide solution to recycle antimony. The second processroute is: black copper sludges were leached directly in the sodium sulfidesolution to recycle antimony. In this subject, the kinetics mechanism ofsodium sulfide leaching was analyzed. The following researches have beencarried out:（1） The optimum process conditions of acid leaching of copper sludgeswere drawn by single factor experiment. The optimum conditions are asfollows: concentration of sulfuric acid is1mol/L, temperture is80℃,liquid-solid ratio is10:1, leaching time is4hours, flowing rate of air is0.7m3/h, rate of stirring is400r/min. Under these optimal conditions, the slagrate is around25%, the leaching rate of copper and arsenic seperately aremore than90%、88.49%while that of antimony is lower than5%. Antimonyis beneficated in the leaching residue, antimony and arsenic are recycledthrongh leaching acid leaching residue in the sodium sulfide solution.Copper and arsenic are recycled from acid leaching solution.（2） The optimum process conditions of sodium sulfide leaching of acidleaching residue sludges were drawn by single factor experiment. Theoptimal process conditions of sodium sulfide leaching are as follow: excesscoefficient of sodium sulfide is1.3, massconcentration of sodiumhydroxide is30g/L, liquid-solid ratio is10:1, leaching time is2.5hours,temperture is85℃, rate of stirring is500r/min. Under these optimalconditions, the leaching rate of antimony、copper and arsenic seperately are85%、81%and1%. Antimony and arsenic are separated effectively fromother metals through sodium sulfide leaching. （3） Maintaining strong alkaline conditions, impure sodium antimonateand sodium arsenate solution are obtained through oxidize sodium sulfideleaching solution usinghydrogen peroxide as oxidant. Sodiumpyroantimonate product is obtained in which the mass fraction of antimonyis48.98%by acidizing、 neutralizing processes using impure sodiumantimonate as material. The product quality of sodium pyroantimonate is upto the first grade standard of china （YS221992）. Oxidation solution isconcentrated, crystallined and precipitated to get sodium arsenate product,the content of Na3AsO4is37.06%～40.57%in the product.（4） The purity98.16%of CuSO₄·5H₂O is obtained from acid leachingsolution after evaporating and crystallizing, the product quality ofCuSO₄·5H₂O is up to the first grade standard of china （GB4371993）. Inorder to realize comprehensive recovery of copper and arsenic, copperarsenate production is prepared using the solution after crystallication ofcopper sulfate, the production could basic meet demands of enterprisestandard.（5） For the second process route, whole process experiments werecarried out reference technological parameters of the first process route.Sodium pyroantimonate product is obtained in which the mass fraction ofantimony is49.11%. The product quality of sodium pyroantimonate is up tothe first grade standard of china （YS221992）. Oxidation solution isconcentrated, crystallined and precipitated to get sodium arsenate product,the concent of Na3AsO4is36.08%～40.02%in the product.（6） Leaching process of antimony and arsenic with sodium sulfide canbe described by the shrinking core model which is controlled by thediffusion in the boundary layer、 product layer diffusion and chemicalreaction not one single step.