Study On The Selective Inhibition Of Cassiterite And Chlorite Flotation In The Sodium Oleate System

Tin is one of the rare metals in the world,its content in the earth’s crust is 0.004%,and the global tin reserves are about 4.7 million tons.Tin ore resources are one of the advantageous mineral resources in China,and the reserves rank first in the world,accounting for 23% of world reserves.However,the ore of tin resources that can be exploited and utilized are poorly endowed with complex dissemination characteristics.As a result,the grade and recovery of tin concentrate are low and the particle size of cassiterite is fine.In the production practice of cassiterite,in addition to quartz and calcite,most of the gangue minerals also contain silicate minerals such as serpentine,chlorite,and amphibole.In addition,chlorite easily adheres to bubbles and floats,polluting the flotation concentrate and causing the quality of the concentrate to decline.In the existing research reports,there are few basic researches specifically for the separation of cassiterite and chlorite,so the selective depression effect of the reagent on the realization of the separation of cassiterite and chlorite is very critical,and it also has certain practical significance.For this purpose,this paper studies the basic research on flotation separation of cassiterite and chlorite and the selective mechanism of depressant on cassiterite and chlorite flotation by means of pure mineral flotation test,artificial mixed ore flotation test,solution chemical calculation,Zeta potential test,infrared spectrum test,and X-ray photoelectron spectroscopy（XPS）.The results of flotation studies show that sodium oleate has a certain ability to collect cassiterite and chlorite,cassiterite has good floatability in weakly alkaline environments（pH=7～9）,and chlorite can float in alkaline conditions（pH=7～9）;At pH=8,the amount of sodium oleate is 1.5×10^-4mol/L,the recovery of cassiterite is 87.89%,and the recovery of chlorite is 29.29%.Among all the depressants used in the test,inorganic depressants（water glass,hexametaphosphate,sodium fluosilicate）,small molecule organic depressants（citric acid,oxalic acid）and xanthan gum have a certain degree of depression on cassiterite and chlorite,and the selectivity is poor;three ionic macromolecular depressants（sodium humate,sodium lignosulfonate,sodium polyacrylate）and locust bean gum,soluble starch have a significant depression effect on cassiterite,but have a small effect on chlorite.A certain amount of carboxymethyl cellulose has a good selective depress ion effect on cassiterite and chlorite.At pH=8,the dosage of carboxymethyl cellulose is 12.5mg/L,the recovery of cassiterite is 92.23% and the recovery of chlorite is 6.25%.The artificial ore mixing test showed that the flotation separation effect was the best when the amount of carboxymethyl cellulose was 6.5 mg/L,at this time,the mixed concentrate yield was 43.98%,the grade of Sn was 75.09%,and the recovery was 82.79%.After sodium oleate interacts with cassiterite and chlorite,the carbon element concentration on the surface of the two minerals increases,the surface Zeta potential shifts negatively,and the characteristic peak of sodium oleate group also appears,indicating that sodium oleate acts on the surface of cassiterite and chlorite with chemical and physical co-adsorption,and the adsorption on the cassiterite surface is not achieved by the direct interaction with the Sn sites on the cassiterite surface,but through the oxygen sites in the hydroxyl compound（Sn-OH） produced by the hydroxylation of the cassiterite surface.The addition of carboxymethyl cellulose can directly affect the adsorption of sodium oleate on the surface of the two minerals,which ultimately makes the chlorite strongly depressed and has little effect on cassiterite,carboxymethyl cellulose shows good selective depression effect on cassiterite and chlorite.After the carboxymethyl cellulose acts on the surface of cassiterite,the carbon atom concentration decreases,the surface Zeta potential shifts slightly,and the characteristic peak of the carboxymethyl cellulose group does not appear,so the carboxymethyl cellulose has weak physical adsorption on the surface of cassiterite which does not have a huge impact on the collection of sodium oleate;After the interaction of carboxymethyl cellulose and the surface of chlorite,the concentration of carbon atoms increases,the Zeta potential shifts negatively,and carboxymethyl cellulose groups appear,the characteristic peak of carboxymethyl cellulose group appears,so there is a hydrogen bond and weak chemical adsorption between the carboxymethyl cellulose and the chlorite surface,which affects the interaction of sodium oleate with the chlorite surface and its flotation results,and then make cassiterite and chlorite effective separate.