Yunnan, A Low-grade Zinc Oxide Ore Flotation Pilot Study

Zinc ore resources are very rich in our country, and the zinc oxide takes a large percent age and its distribution centralizes. Zinc oxide is a secondary zinc mineral and a great variety.The main zinc oxide minerals include:Smithsonite (ZnCO3), willemite (ZnSiO4), hemimorphite (H2ZnSiO5或Zn2SiO4·H2O), water zinc [3Zn(OH)2·2ZnCO3],zincite (ZnO), and so on.At present the main flotation method used at home and abroad are:Sulfide-amine salt flotation, sulfide-xanthate flotation, the fatty acids collector flotation and the flocculation flotation, and so on.One kind of zinc oxide ore in Yunnan is dolomite type, with a high rate of oxidation rate. The valuable minerals are secondary zinc ore which formed by efflorescence and oxidation (smithsonite, etc.), and gangues are dolomite in the main, followed by quartz, limonite, few feldspar and micro pyrite.The samples appear mixed depth of brown color, with less loose block, more earthy and powdery, micro-mud crystal, sparsely dipping, crusting and concentric ring banded structure.The results of research showed that the zinc oxide ore was mainly composed of smithsonite, with small particle size, mineral crystal for the mud (<0.03mm) dispersing in the basis of dolomite. The dolomite appeared the micro-mud crystal structure (<0.03mm). The limonite existed among the dolomite and smithsonite, distributing as the type of impregnation, and its size was generally 0.005～0.03mm.Considering the nature of the ore, a pre-trial for removing mud and a series of medicament exploration experiment were carried on, and eventually the program was determined as follows:the new collector YX-1 was adopted as the collector of the zinc oxide ore flotation and sodium carbonate, sodium silicate and sodium hexametaphosphate were taken as the depressor for gangue and sludge dispersant,2# oil as the foaming agent. In the basis of conditioned experiment, after grinding the run-of-mine to 95%-0.074mm and three roughings and two cleanings, the grade of zinc concentrate was 32.74%, and the recovery was 61.64%.Open flowsheet was used in the experiment because of mud,and the middlings can take some zinc metal, therefore,we have conducted the middlings. The flotation was used to select the middlings, after two cleanings, the grade of zinc concentrate was 16.78% and the recovery was 69.70%, and the grade of tailings reached to 1.92%. The recovery utilization rate of the valuable minerals has been raised by the concentrate conduction of middlings.New collector, YX-1, is a kind of synthetic amine collector, which can enhance the effect on the amine numerator and improve the collection character by the co-operate effect of the medicament and adding appropriate emulsifier. Test results show that the new collector YX-1 of the zinc oxide has a good effect, that is to say, having good collection character to the impregnate zinc oxide.Given that the ore contains a large amount of mud, and the following classification work will be affected greatly in closed circuit process, open flowsheet is suggested in the production.