Experimental Study On Flotation Separation Of Copper-lead-zinc Sulfide Mixed Concentrate

Copper,lead and zinc are strategic mineral resources in China.They are widely used in national economy and national defense construction and occupy an important position.Cu-Pb-Zn polymetallic sulphide ore is an important source to extract copper,lead and zinc.However,due to the complex mineral composition and similar floatability between minerals,the flotation separation process is generally complicated.Mixed flotation is often used to acquire Cu-Pb-Zn mixed concentrate,and then separate the mixture into copper,lead and zinc.The first reason for the difficulty in sorting mixed concentrate is that the residual agent on the surface of the mixed concentrate will cause the foam to become sticky and cause fine-grain entrainment.Secondly,the sphalerite in the mixed concentrate has been activated by Cu²⁺and Pb²⁺in frontal flotation,thus obtaining good floatability.In this way activated sphalerite and copper-lead minerals can not be separated effectively.The Cu-Pb-Zn mixed concentrate which is obtained from the mixed-preferential flotation process of Xuzhou polymetallic sulphide ore is taken as the research object in this paper.Based on the determination of the separation flotation process and the optimum reagent system,we focused on the study of reagent removal process,selection of high-efficiency collectors and effective depressants of sphalerite,and obtained the following conclusions:The pure mineral flotation experiments of chalcopyrite and sphalerite showed that the natural floatability of chalcopyrite was better than that of sphalerite.Under three collector systems?butyl xanthate,DDTC,Z-200?,chalcopyrite had good floatability throughout the wide pH range,while sphalerite was less floating under alkaline conditions,so it was more conducive to separation of two minerals under alkaline conditions.Considering the selectivity and collecting ability,Z-200 was chosen as the chalcopyrite collector.Cu²⁺could significantly improve the floatability of sphalerite.The floatability of sphalerite which was activated by Cu²⁺was not much different from that of chalcopyrite and therefore it was difficult to separate them.The combined depressants?ZnSO₄+Na₂SO₃?had a significant inhibitory effect on the activated sphalerite,but had little effect on the chalcopyrite.Therefore,when Z-200was used as a collector,the addition of combined depressant could achieve efficient separation of chalcopyrite and activated sphalerite.The mixed concentrate test showed that the mixed concentrate containing3.75%copper,7.85%lead and 41.78%zinc was de-reagent by sodium sulfide,and ZnSO₄+Na₂SO₃ was used as depressants,Z-200+DDTC was used as collectors in roughing process.After the open circuit test with a roughing process and a selected process,Cu-Pb mixed concentrate?Cu grade of 15.21%,Cu recovery of 76.29%,Pb grade of 27.44%,Pb recovery of 65.75%,Zn grade of 7.66%?and Zn concentrate?Zn grade of 53.24%,Zn recovery of 90.29%,Cu grade of 0.03%,Pb grade of 2.10%?was finally obtained.Infrared spectroscopy testing showed that when the pH value of the solution was8,the adsorption of Z-200 on the surface of chalcopyrite is stronger than that on the surface of sphalerite,indicating that Z-200 could be used as the efficient collector of chalcopyrite.When the pH value of the solution was 10,the adsorption of DDTC on the surface of chalcopyrite was strong,but it was difficult to observe obvious adsorption on the surface of sphalerite,indicating that DDTC had good selectivity for two minerals.The adsorption amount test showed that sodium sulfide had a strong desorption effect on the butyl xanthate adsorbed on the surface of chalcopyrite and sphalerite,verifying the desorption effect of sodium sulfide.The adsorption amount of the collector on the mineral surface and pH of the slurry were closely related:Z-200had good selectivity to chalcopyrite and sphalerite under neutral-weak alkaline conditions,while DDTC had good selectivity to the two minerals under strong alkaline conditions.