铁矾渣提铟及铁资源利用新工艺研究

【作者】 覃宝桂；

【导师】 唐谟堂； 邹魁；

【作者基本信息】 中南大学 ， 有色金属冶金， 2010， 硕士

【摘要】 为简化现有铁矾渣提铟流程,提高铟的直收率,消除低浓度SO2烟气排放危害,本论文提出了"NaOH分解-稀盐酸浸出-还原-TBP萃取”的含铟铁矾渣湿法处理新工艺。首先在NaOH体系中分解铁矾渣,产出Na2SO4溶液和含In、Zn的铁渣。前者经净化除杂、浓缩结晶回收芒硝后返回分解工序；后者则在盐酸体系选择性浸出和TBP萃取In、Zn,浸出渣经磁选富集后作为炼铁原料。碱分解试验结果表明,在WNaOH:W铁矾渣=0.3814：1、温度60℃、液固比2：1、时间2h的最优条件下,铁矾渣分解率高达98.03%,As的浸出率为83.36%,In、Cu、Pb、Cd、Ag、Zn、Sb、Sn等有价金属绝大部留于分解渣中。碱分解过程中,铁主要以Fe3O4形式入渣。在温度40℃、液固比7：1、反应时间2h、MHC1/MTheory=1.8的最优条件下用稀HCl浸出分解渣,In、Zn、Cu、Cd、As、Sn、Sb、Pb、Ag的渣计浸出率分别为98.26%、99.35%、98.79%、98.93%、76.27%、68.50%、80.12%、64.82%和60.80%。89.25%的Fe留于浸出渣中,渣含Fe高达52.48%,经磁选富集和除杂后可作为炼铁原料。在温度50℃、时间25min、铁粉用量为1.5倍理论量的最优条件下,采用铁粉还原浸出液中的三价铁并置换除杂。Fe3+的还原率达到99.90%,而As3+、Sb3+、Bi3+的脱除率分别为63.95%、100%和97.65%,In的损失率<1%。采用70%TBP+30%磺化煤油的有机相同时萃取净化液中的In、Zn,在相比O／A=1.5：1、室温、水相初始酸度1.5mol·L-1振荡及静置分层时间均为10min、三级逆流萃取的最佳工艺条件下,In、Zn平均萃取率分别为98.13%和99.05%,而Fe2+的萃取率小于1%。采用纯水反萃铟锌负载有机相,在室温、3级反萃、相比O／A=3：1、振荡和静置分层时间均为5min的最佳工艺条件下,Zn、In平均反萃率分别达到93.62%和99.10%。从萃取原液到萃余液,Zn、In的直收率分别为92.73%和97.24%。反萃液在常温下用锌板置换反萃液产出海绵铟和ZnCl2溶液,铟置换率大于99%。“NaOH分解-盐酸浸出-还原-TBP萃取”的含铟铁矾渣湿法处理流程实现了铁渣和低浓度502烟气的零排放,In和Zn的直收率大幅提高。浸出渣中的铁Fe含量高达52.48%,经磁选富集和除杂后可作为炼铁原料,可以实现锌精矿铁资源利用并消除铁渣排放对生态环境的污染。更多还原

【Abstract】 To simplify current process of indium extraction from jarosite residue, raise direct yield of indium and eliminate the polution of low concentration SO2, a new process of "NaOH decomposition-dilute hydrochloric acid leaching-reduction-TBP extraction" was proposed in this disseration. Jarosite residue was firstly decomposed in NaOH medium to produce Na2SO4 solution and iron residue bearing indium. Na2SO4 solution was concentrated and then refrigerated crystallization to recover mirabilite after arsenic removal, mother liquid was recycled to alkaline decomposition operation. After selective leaching of In and Zn with dilute hydrochloric acid, the magnetic separation of leached residue was carried out to produce iron concentrates that used as raw material in iron smelting. Indium and zinc in pregnant solution were simultaneously solvent extracted by TBP.The results of NaOH decomposition show that he decomposition ratio of ammonium jarosite can reach 98.03% under the following optimum conditions:WNaOH/WJarosite=0.3814:1,60℃, L/S ratio 2:1,2h. Impurity elements like Zn, In, Cu, Cd, Pb, Sb, Sn and Ag, are left in residue, while 83.36% of As is leached into pregnant solution in presence of AsO43-. DSC-TGA thermal analysis and XRD characterization results demonstrate that Fe is precipitated in form of Fe3O4 during alkaline decomposition. The content of Fe, In and Zn in decomposition residue is 38.81%,0.23% and 12.89%, respectively. After selective leaching with dilute HC1, the leaching ratio of In, Zn, Cu, Cd, As, Sn, Sb, Pb and Ag is 98.26%,99.35%,98.79%,98.93%,76.27%,68.50%,80.12%,64.82% and 60.80%, respectively, under the following optimum conditions:40℃, L/S ratio 7:1,2h, MHC1/MTheory=1.8.89.25% of Fe is left in leached residue with grade of 52.48%. After magnetic separation and impurities removal, iron concentrate obtained can be used as raw material for iron smelting.Impurity ions such as As3+, Sb2+ and Bi2+ in pregnant solution were removed by iron scrap, and their removing rate is 63.95%,100%, and 97.65%, respectively, at 50℃for 25min with iron scrap addition of 1.5 times of theoretical consumption. The reduction ratio of Fe3+ is closer to 100%, and the loss ratio of indium is lower than 1% during iron replacement process. Zn2+ and In3+ in purified solution were solvent extracted with 70%TBP+30% sulfated kerosene at room temperature for 10min with phase ratio of 1.5:1. After three-stage of countercurrent solvent extraction, the extraction ratio of Zn and In is 98.13% and 99.05%, respectively, while that of Fe2+ is lower than 1%. Zn2+ and In3+ in loaded organic phase was stripped by distilled water at ambient temperature for 5min with phase ratio of O/A=3:1. After three-stage of countercurrent stripping, the stripping rate of In and Zn is 99.10% and 93.62%, respectively. From purified solution to stripping solution, the total recovery ratio of Zn and In is 92.73% and 97.24%. Zinc plate was added into stripping solution to replacement sponge indium and purified ZnCl2 solution. The replacement rate of In3+ is higher than 99%.In the present process of "NaOH decomposition-dilute hydrochloric acid leaching-reduction-TBP extraction", iron residue and SO2 off-gas are not produced and the direct yield of In and Zn are higher. Iron content in the leached residue is 52.48%, which can be concentrated by magnetic separation as ironmaking raw materials. Consequently, iron resource in zinc concentrates can be utilizated and the environmental pollution due to iron residue emission are also eliminated更多还原