The Basic Theory And Sorting Process Of Recovering Copper And Nickel From Acid-modified Flotation Of Jinchuan High-magnesium Tailings

Nickel is an important nonferrous metal which is widely used in defense industry and civil industry.It holds an important status in the national economic system.It has a shortage of nickel resources,accounting for only 3.7%of the world’s nickel resources in China.The available resources are mainly the bearing-copper and nickel sulfide ores which are bearing magnesium silicate minerals.Because of the gangue which is easily associated with the valuable mineral and easy to slime,a large amount of copper and nickel is lost in the tailings.Therefore,the utilization of tailing is vital.It is said that 62%nickel resources are mainly distributed in Gansu Province of China.Jinchuan company as domestic nickel industry’s largest production base,the nickel smelting scale ranks the second in the world.After more than 50 years of development and utilization,tailing dam store up 120million tons of tailing.Now,it is still increasing sharply at the more than 9million tons of tailing,and the amount of nickel and copper metal lossed in the tailing both by up to 20,000 tons every year.By developing beneficiation technology,it can be made nickel/copper useful mineral adequately recycling.It will not only relieve shortage of raw ore,but also bring substantial economic benefits.The flotation tailings bearing magnesium silicate minerals of Jinchuan have been selected as the research object.The basic theory of acid modified flotation is studied systematically by Zeta,adsorption method,slurry viscosity,turbidity detection,contact angle,SEM,XPS and DLVO spectrum analysis.Based on it,the paper discovered the rule of hydrophily or hydrophobicity of Mg-removed serpentine,and explained the variation of serpentine influenced flotation behavior of nicopyrite and copper.At the same time,the influence of ions in the acid solution to mineral floatability was investigated.It’s going to clear up the feasibility of separate bearing-copper and nickel sulfide mineral from magnesium silicate minerals by acid modified flotation.In the process of acid modified flotation,Mg is removed from the serpentine surface on the premise of not broken the crystal structure of serpentine.The Zeta of Mg-removed serpentine move in the direction of the negative axis comparison to that PZC of serpentine is 10.2.The PZC of serpentine in the rate of 32.27%Mg-removed is 6.9 and the rate of 85.53%Mg-removed is 4.3.The contact angle of serpentine is 39.2°,but the contact angle of serpentine in the rate of 32.27%Mg-removed is 34.72° and the rate of 85.53%Mg-removed is 30.86°.It will solve the problem of hetero-aggregation and concentrate bearing MgO in theory,when it recycles bearing Cu-Ni sulfide mineral from tailing by flotation.The result from micro-minerals tests showed that the floatability of serpentine is low with butyl xanthates as collector,but recovery is closely related with particle size.The results from mixed minerals system tests showed that the depressing effect of serpentine on nicopyrite and chalcopyrite were significantlyimproved with the increasing contents and the decreasing particle size of serpentine.Moreover,the Mg-removed serpentine was not floated and the inhibiting effect was weaker between Mg-removed serpentine and bearing Cu-Ni sulfide mineral,in the butyl xanthate system.According to the DLVO theory,the total potential energy between mineral particles showed that the mutual attraction turns to repellant between serpentine and besring Cu-Ni sulfide mineral with the butyl xanthate as collector,when the Mg2+ of serpentine surface is removed.The less of hetero-aggregation was beneficial to improve the flotation environment and optimize concentrate quality.In the process of acid modification,the results from ions on the mineral flotation and the analysis of XPS indicated that Cu2+ and Ni2+ could activate the serpentine,and the activation of Cu2+ is all the better with the pH>6,while Cu2+ and Ni2+ could not activate the Mg-removed serpentine.In the pH>7,Mg2+、Fe2+ and Fe3+ could depress the floatability of nicopyrite,while they are barely depress the floatability of chalcopyrite.Mg2+ played more effect than Fe3+ and Fe2+ in flotation.The study of the action with ions showed that they needed magnesium ion as the activated sites by the adsorption forms of oxyhydroxide precipitation on the serpentine surface.Because of the Mg2+ of serpentine surface removed,activated sites of Cu and Ni were cut down.The oxyhydroxide precipitation on the serpentine surface was reduced,so the Mg-removed serpentine couldn’t be floated.The flotation results from low-grade bearing copper-nickel sulfide tailing with the high content of magnesium silicate minerals from Jinchuan showed that the bulk concentrate can be gained by acid modified flotation.The grades of Cu and Ni respectively are 4.58%and 3.02%,in the meantime,the recovery of Cu and Ni respectively are 21.70%and 18.48%,while the content of MgO is 4.86%.The result reachs to the expected objective.In the paper,the acid modified flotation basic theory system of bearing copper-nickel sulfide tailing with high content magnesium silicate minerals had been preliminarily established.The rules of hydrophily and hydrophobicity of serpentine were investigated.It also developed and improved the bearing Cu-Ni sulfide mineral flotation system.It supported the technology for solving the difficult problem of recycle the low-grade bearing copper-nickel sulfide tailing with magnesium silicate minerals and high content of magnesium in concentrate.Therefore,the research results provided an important theoretical basement and a new researching direction with the reutilization of bearing Cu-Ni tailing.