| Secondary zinc oxide, the sediment soot was produced in the process of smeltingZinc and Lead imperial smelting process (ISP) slag by fuming furnace. It is chargecharacters as follow: (1) the quantity is great. (2) the accompanied scattered metalindium was enriched. (3)The content of arsenic is very high, 40～50％arsenic whichwas contained in the material was enriched in the secondary zinc oxide, the arseniccontent reach 8～10％. (4)It contains many kinds of valued metal such as Zn, Pb, In,Ag and Bi which could be recycled.The above characteristics show that: thesecondary zinc oxide was worth recovery, but the severe interfere of Sn, Sb, Fe, As,the destroy to the environment from the poisonous elements As, Pb, Cd are allincrease the price of the comprehensive recovery and hardness of technic.Based on the methods, technics and research development of recycling valuedmetals form various zinc slag, combined with the characteristic of secondary zincoxide, this research has brought forward a new technic on comprehensive recovery ofthe secondary zinc oxide. This technic can comprehensively recycle many metals suchas Zn, In, As, Bi, Pb and Ag at the lowest cost, efficiently and environmentallyconscious, and reduce the release of waste residue in the zinc-smelting industry.Five key technical problems in the process of comprehensive recovery of thesecondary zinc oxide were resolved in this technic:At first, the crystallographic component and host occurrence state were analyzedby XRF and XRD instrument, conjoining with lixiviation kinetics, the effects of theacidity, ratio of solid and liquid, temperature, time, particle size and oxidant on thelixiviating rate of indium were studied. The optimal lixiviation conditions wereconfirmed; the lixiviation rate of indium could reach up to 97％.Secondly, the technology of precipitate removing impurities was introduced inthe process of purifying the lixivium in which contain indium. The removal efficiencyof As, Sb, Sn in the lixivium can reach up to 99％, 95％, 86％respectively, and theloss rate of indium is less than 2％. The purified lixivium can be used to extractindium direct after being deoxidize with iron powder. Thirdly, base on the analysis of molecular frame and assign characteristic of P204,the principium of extracting indium with P204 were researched. On thermodynamicsaspect, the extraction equilibrium constant log KΘand other thermodynamicsquantum were working-out using extrapolation method. On the aspect of extractiondynamics, the process of extracting indium was taken apart. The affections of P204concentration, acidity of lixivium, time of extraction, impurity iron to the extractionratio of indium were researched. Meanwhile, the problem of emulsification in theprocess of extraction was researched.Fourthly, the residue of indium dross leaching could be used to oxidate-muriaticacid leach-hydrolytic recycling bismuth, leach plumbum with ammonium acetate tomake stearic acid lead, leach with ammonia to recycle silver. This technics canseparate and enrich each valued metals efficiently. The indium-raffmate was used torecycle zinc to make zinc chloride or zinc sulfate, successfully realized thecomprehensive recovery of valued metals and management of waste water.At last, the distribution of the poisonous element arsenic in the process of thecomprehensive recovery was studied, and the method of recycle arsenic was proposed.This could greatly minish the cost of production and the damage to the environment inthe process of comprehensive recovery.In all, this technology has many merits such as higher rate of recovery, lowercost, less waste release and so on. The release quantity of waste slag could reduce83％, the harmful element arsenic could reduce 95％; the discharging water can meetthe national standard. It can be used to discharge directly or return for reuseing.
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