Technical Studies On Hot Acid Leaching-removing Ferric Ion By Lead Jarosite

Using the process of "three stage leaching-reduction by zinc concentrate-neutralizing for precipitation of indium" to deal with high-lead containing zinc calcine for recycling valuable metals, the experimental results show that a large number of ferric ion will be precipitated under the following conditions, which are the higher temperature and lower final acid concentration in low-acid leaching process. Aimed at finding this reasons, the process of low and high acid leaching zinc ore with high iron content were studied. A new topic of "hot acid leaching-removing ferric ion by lead jarosite" was proposed in present dissertation, studies on the formation mechanism and application of lead jarosite was carried out. The new technique of "hot acid leaching-lead jarosite removing ferric ion-sulfation roasting" was proposed, realizing the separation of iron’zinc and regeneration of sinking agent.The experimental results show that Fe3+is precipitated as hydronium jarosite and lead jarosite, Fe3+is partly substituted In3+to form a more complex jarosite containing indium under the following conditions, which are the higher temperature and lower final acid concentration in low-acid leaching process by three-stage leaching high-lead containing zinc calcine.Studies on the formation conditions and mechanism of lead jarosite was carried out thoroughly. Lead jarosite can form under the following conditions, which are low acidity (pH>0.7) and high temperature (>75℃); the increase of concentration of ferric ion, the extension of time, the increase of the content of the lead sulfate and the presence of seed are beneficial to the formation of lead jarosite; Using ammonium acetate to deal with lead jarosite residual, residual PbSO4of lead jarosite residue is selectively dissolved to leave a "pure" product-lead jarosite seed; The ion reactive of the formation of lead jarosite in sulfuric acid system goes as follow:PbSO4=Pb2++SO42-, Pb2++6Fe3++4SO42-+12H2O=PbFe6(SO4)4(OH)12+12H+Studies on lead jarosite removing ferric ion and leaching of lead jarosite residue was carried out thoroughly. Lead sulphate was used for removing ferric from the low-acid leaching solution, the precipitation ratio of Fe and In can reach to95.47%and94.87. The leaching ratio of Zn, Fe and In can reach to97.60%、98.41%and97.92%by pretreat the lead jarosite residue with sulfation roasting before leaching. The pH of leaching solution is about1.0, this is beneficial to neutralization precipitation indium. High-lead residue can be returned to remove ferric; The behavior of impurities during the precipitation of lead jarosite goes as follow:the most of arsenic antimony indium tin together with ferric entered to the lead residue, a handful of copper and cadmium entered to the lead residue.This topic provides theoretical bases for the feasibility of using "hot acid leaching-removing ferric ion by lead jarosite" to treat zinc ore with high iron content, possessing extensive application foreground; and furthermore, improves the theoretical study on "ferrum-removal by jarosite from sulfuric acid solution", possessing a certain academic reference value.