Study On Flotation Of Microcrystalline Graphite Based On High-intensity Shear Selective Flocculation Conditioning

The crystal size of microcrystalline graphite is extremely small,which leads to serious contamination problem and poor flotation performance.Therefore,the microcrystalline graphite in our country is still directly used or just primarily processed,resulting in a tremendous waste of resources.In this paper,microcrystalline graphite is taken as the research object.The flotation regularities of microcrystalline graphite were investigated using conventional flotation and flotation of high-intensity shear conditioning.The influence of conditioning on the flotation of microcrystalline graphite and methods for further optimization were explored.The significance of factors affecting the flotation performance was also explored while the optimum flotation conditions were obtained.The main conclusions are as follows:The size distribution,mineral composition,dissociation character and wettability of the sample were expounded.The ash content was 14.20%(the grade was 81.58%)and the average particle size was 3.62 μm.The results of SEM show that the sample was liberated sufficiently and the main gangue mineral was quartz.The wettability of graphite and gangue particles varied greatly.The fine grain size will become the challenge in the flotation of microcrystalline graphite.The flotation regularities of microcrystalline graphite were investigated.Under the optimum conventional flotation conditions,the concentrate ash content was 12.12%,the yield was 81.15% and the flotation efficiency index was 13.14%.The results indicate that microcrystalline graphite cannot be recovered efficiently by conventional flotation(flotation speed: 1000~2800 rpm).However,the flotation performance was improved considerably using flotation of high-intensity shear conditioning.The concentrate ash content decreased by 4.31%,the yield increased by 9.85% and the flotation efficiency index increased by 35.43%(flotation speed: 10000~28000 rpm).The concentrate ash content decreased and the tailing ash content increased with the increasing agitation time.However,the prolonged agitation time caused poor performance.The collector dosage had significant impact on the flotation performance.The concentrate ash content was in proportion to the conditioning and flotation concentration.The optimum frother dosage was 1 kg/t and the suitable aeration quantity was 100 L/h.Three different optimization methods including changing surface charge,adding depressants and using emulsified collector were explored.The results show that these methods can reduce the concentrate ash content efficiently and further improve the flotation performance.Based on the flotation regularities and optimization methods,the significance of factors affecting the flotation performance was explored and the optimum flotation conditions were obtained.The agitation speed had an appreciable effect on the concentrate ash content and the collector dosage had significant impact on the concentrate yield.The optimum agitation speed,agitation time and collector dosage were 27173 rpm,20 min and 79 kg/t.Under these optimum flotation conditions,the concentrate ash content and yield can reach to 7.81% and 91.00%.