Study On The Entrainment Behavior Of Easy-to-slime Minerals In Flotation Process And Its Mechanism

With the advancement of industrialization in China,the high-grade ore resources are increasingly scarce,while the lean ore resources contain a large number of gangue minerals with low hardness.In the grinding operation,these gangue minerals are prone to over-grinding and eventually become slime.During the flotation process,due to the small particle size,large specific surface area and high surface energy of the mineral particles,slime minerals are easy to be entrained into the foam layer,or adhered to the surface of the valuable minerals,accompanied with valuable minerals and become the flotation concentrates,thereby reducing the purity of flotation concentrate.Therefore,in view of the influencing factors of easy-to-slime mineral entrainment behavior and proposing methods to effectively regulate the entrainment behavior of easy-to-slime minerals have important theoretical and practical significance for promoting the efficient development and utilization of lean ore resources in China.In this paper,the entrainment behavior of serpentine in brucite froth flotation,the entrainment behavior of talc in chalcopyrite froth flotation,and the entrainment behavior of chlorite in hematite reverse flotation were carried out by a modified Hallimond tube.The influencing factors of the entrainment behavior in the flotation process were systematically analyzed,and the effective regulator for the entrainment behavior of these three types of slime minerals was determined.By means of fourier transform infrared spectroscopy(FTIR),zeta potential analysis,contact angle measurements,surface tension measurements,pulp viscosity measurements and laser particle size analysis,and combined with E-DLVO theory and Plateau foam structure theory,the different mechanism of regulators act on these three kinds of slime minerals was analyzed.In the sodium oleate flotation system(pH=8.5),serpentine enters the foam layer mainly by entrainment(mineral particles enter the foam layer through the non-selective carrying action of the liquid film on the surface of the bubble),and the entrainment rate of fine-grained serpentine is higher than that of coarse-grained serpentine.The finer the core diameter,the higher the entrainment rate of serpentine.For the core diameter of 40?50?m,the entrainment rate of-10?m serpentine is 0.785.Single mineral flotation tests showed that the concentration of serpentine had no effect on its entrainment rate.The higher the concentration of sodium oleate,the greater the inflation rate and the greater the pH of the pulp,the greater the entrainment rate of serpentine.The higher the concentration of Ca2+ and the lower the concentration of Mg2+ in the pulp,the higher the entrainment rate of serpentine,while Fe3+ concentration is almost no effect on the entrainment rate of serpentine.Calcium lignosulfonate cannot only inhibit the floatability of dolomite,but also effectively reduce the entrainment rate of serpentine,thereby improving the purity of the brucite flotation concentrate.In the methyl isobutyl carbinol(MIBC)flotation system(pH=10),the finer the particle size of talc,the lower the true flotation recovery rate(mineral particles are collected selectively by the collector to enter the foam layer)and the higher the entrainment rate of talc.The finer the core diameter,the lower the talc recovery rate by true flotation,and the higher the entrainment rate of talc.For the core diameter of 40?50?m,the true flotation recovery of-10?m talc is 8.448%,and the entrainment rate is 1.145.Single mineral flotation tests indicated that the concentration of talc had no effect on its entrainment rate.The higher the concentration of MIBC,the greater the inflation rate and the smaller the pH of the pulp,the higher the entrainment rate of talc.With the increase of the concentration of Fe3+,Mg2+,Ca2+and Cu2+,the entrainment rate of talc decreased.Guar gum can effectively reduce the entrainment rate of talc and has almost no effect on the flotation recovery of chalcopyrite.In the sodium oleate flotation system(pH=11.3),the finer the particle size of chlorite,the lower the true flotation recovery rate and the higher the entrainment rate of chlorite.The finer the core diameter,the higher the chlorite recovery rate by true flotation,and the higher the entrainment rate of chlorite.For the core diameter of 40?50?m,the true flotation recovery of-10?m chlorite is 5.425%,and the entrainment rate is 0.823.Single mineral flotation tests demonstrated that the concentration of chlorite had no effect on its entrainment rate.The higher the concentration of sodium oleate,the greater the inflation rate and the greater the pH of the pulp,the higher the entrainment rate of chlorite.Fe3+ in the pulp can reduce the entrainment rate of chlorite,while Mg2+and Ca2+can increase the entrainment rate of chlorite.The low concentration of citric acid in the pulp can effectively increase the entrainment rate of chlorite,thereby reducing the content of chlorite in the hematite concentration.E-DLVO theoretical calculation results indicated that fine-grained chlorite is easily adsorbed on the surface of hematite,resulting in lower removal rate of chlorite.After the addition of citric acid,the interaction force between chlorite and hematite becomes repulsion,and a large number of fine-grained chlorite entered into the foam layer by entrainment,thereby effectively increasing the removal rate of chlorite,and finally improve the anti-flotation concentrate index of hematite.The particle size analysis results of artificial mixed ore of hematite and chlorite before and after citric acid treatment are consistent with the calculation results of E-DLVO theory.According to the average flow velocity of Plateau fluid micro-components,the addition of calcium lignosulfonate can effectively increase the surface tension of sodium oleate solution(pH=8.5),and increase the average flow velocity of fluid micro-components.Therefore,a large amount of fine serpentine which is entrained into the foam layer flows out with the liquid,thus effectively reducing the entrainment rate of serpentine and improving the index of the brucite concentrate.The above results are further confirmed by foam stability test results.During the flotation of chalcopyrite,guar gum can be chemically adsorbed on the surface of talc,thereby reducing the contact angle of talc and increasing its hydrophilicity.Meanwhile,guar gum can also selectively flocculate fine-grained talc,thereby significantly increasing the apparent particle size of fine-grained talc,reducing the foam entrainment rate and improving the purity of the chalcopyrite flotation concentrate.In this paper,the entrainment behavior of three easy-to-slime minerals such as serpentine,talc and chlorite was studied during flotation.The research results of this thesis enriched the theoretical system of non-selective entrainment behavior of easy-to-slime minerals during foam flotation.This paper has certain guiding significance for the flotation of serpentine-bearing brucite,the flotation of talc-bearing chalcopyrite and the flotation of chlorite-bearing hematite,and provides theoretical support for the efficient development and utilization of low-grade mineral resources.