Applied Fundamental Research Of Comprehensive Recovering Valuable Elements From Cyanidation Tailing

Cyanidation tailing from gold industry is one of the bulk hazardous waste in our country.Landfill of cyanidation tailing not only causes irreparable harm to surrounding environment and ecology,but also causes the waste of valuable elements contained in the tailing.It is of great significance to research on the treatment of cyanidation tailing in order to realize the comprehensive utilization of valuable elements in the tailing and convert it into harmless solid waste.Firstly,this paper aimed at the analysis of the chemical and physical properties of cyanidation tailing from four gold plants with different storage time.The mineral composition of cyanidation tailing mainly contained pyrite and quartz.The valuable elements were copper,lead,zinc,sulfur and iron,which mainly existed as sulphide ore.The grades of copper,lead and zinc were only 0.2 to 0.6%,increasing the difficulty of flotation separation.Besides,the particle size of cyanidation tailing was very fine with 90%grain sizes less than 50 microns,which caused the slime entrainment in flotation.The main differences between various cyanidation tailing embodied in the surface properties,such as pH value and total cyanide value.The storage time also influenced the pH and cyanide content of cyanidation tailing.The pH and cyanide content became lower and lower with storage time going on,as the tailing might react slowly with oxygen to may produce acid.The acid could neutralize the pH value and release the cyanide.Secondly,the influence of cyanide on flotation of valuable elements were studied by Eh-pH and IR test.The test results showed that the recovery of chalcopyrite,galena,sphalerite,pyrite in cyanide-containing water were very low.IR results showed that there was CN group absorbed on the surface of sphalerite and pyrite,which explained that cyanide can strongly inhibit the flotation of sphalerite and pyrite for its hydrophilia.In order to decrease the influence of cyanide,it is essential to remove the cyanide from cyanide-containing water.On the basis of conventional cyanide removal methods,such as acid treatment,ferrous sulphate precipitation method,copper sulfate precipitation method,and hydrogen peroxide oxidation method,this paper put forward to use persulfuric compound to remove cyanide efficiently.The persulfuric compound could oxidize free cyanide into nontoxic carbon dioxide and ammonia.And the Cu2+ in the water combined with ferricyanide to form bimetal cyanide complex.A small amount of Cu2+ reacted with thiocyanide ion to generate Cu(SCN)2,which quickly transformed into CuSCN to precipitate from solution.As a result,the cyanide and metal ions in cyanide-containing water were removed almost completely.Thirdly,we developed a composite RX-2,which was composited by weak oxidizer,polyphosphate and starch for the purpose of Cu-Pb bulk flotation.This reagent had dual function of activation and dispersion.Flotation dynamics results showed that the copper-lead bulk flotation accorded with classic first-order kinetics model.The flotation rate constant with RX-2 as activator was bigger than that without RX-2,indicating that RX-2 could promote the flotation of chalcopyrite and galena.Cycle voltammetry curve and XPS test results showed that RX-2 with proper dosage reinforced more elemental sulfur S0 generated on the surface of chalcopyrite and galena,which was hydrophobic and beneficial to flotation.The maximum recovery of chalcopyrite and galena can be achieved with RX-2 dosage of 1200 g/t.In the recovery of copper,lead,zinc and pyrite from cyanidation tailing,hydrocyclone was used in pretreatment process to remove very fine slime.Combined with RX-2,a Cu-Pb bulk concentrate was achieved.Then,the copper-lead bulk concentrate was separated by modified CP mixture effectively.The copper-lead bulk tailing was treated with copper sulfate to achieve sphalerite concentrate.The sphalerite tailing served as pyrite feed to achieve pyrite concentrate.Finally,a copper concentrate,a zinc concentrate,and a sulfur concentrate were accomplished in the "Cu-Pb bulk flotation;Cu-Pb separation;Zn flotation;S flotation" flotation flowsheet,realizing the comprehensive recovery of valuable elements from cyanidation tailing.