| The excellent performance of inflatable flotation column in fine particle flotation domain can effectively deal with the problems of resource depletion and secondary resource reuse.Different from the flotation machine,the inflatable flotation column is superior for the"static separation".Spray injector is a typical bubble generator widely used in inflatable flotation column.It has the advantages of simple structure,convenient maintenance,high efficiency and energy saving.However,during bubbling,the excessive kinetic energy is generated from the spray injector,once kinetic energy dissipation is not high enough,the slurry turbulence in the flotation column will be too high and unfavourable for"static separation"in the flotation column.Therefore,this paper focuses on the problem solving of the kinetic energy dissipation of spray injector affects the foaming effect in the two stages which are bubble generation stage and bubble buoyancy stage.Under the guidance of theoretical research,the method of regulate control of kinetic energy dissipation was developed to improve the foaming effect in inflatable flotation column.The feasibility of the regulate control was verified by bubble generation stage research,bubble buoyancy stage research,numerical simulation and industrial beneficiation research.The research results show that the turbulent kinetic energy in the inflatable flotation column is dissipated more quickly and the foaming effect is effectively improved after the regulate control of kinetic energy dissipation is adopted.The main conclusions of the research on the influence of kinetic energy dissipation on foaming effect are as follows:1.The empirical calculation formula of flow rate and flow velocity of the bubble generated by spray injector within the medium of slurry of flotation column,the theoretical calculation formula of kinetic energy and velocity of floating bubbles were deduced,It is concluded that the lower bubble velocity can reflect the higher bubble kinetic energy dissipation velocity and the better foaming effect.The concept of the average velocity of bubble buoyancy in laboratory research column was presented first time,which provided a unified evaluation standard of kinetic energy dissipation and foaming effect for foaming research under different conditions in laboratory.2.The bubble velocity can be controlled effectively and kinetic energy dissipation can be accelerated by changing the nozzle diameter or the type of bubble generator in the bubble generation stage.The average velocity of bubble floating can be reduced from 450 mm/s to 260 mm/s by using two small diameter spray injectors instead of a single large diameter spray injector,and the average velocity of bubble floating can be reduced from 450 mm/s to 230 mm/s by using rubber microporous aerator instead of spray injector as bubble generator.3.The bubble velocity can be controlled effectively and kinetic energy dissipation can be accelerated by adding energy dissipation plate in the bubble buoyancy stage.The average flow rate of bubble rising can be reduced from about 400 mm/s to less than 300 mm/s by adopting the regulation mechanism of adding energy dissipation board in bubble buoyancy stage,no matter using single-layer flat energy dissipation plate,double-layer flat energy dissipation plate or conical dissipation plate.4.The geometrical height of flotation column can be greatly reduced by speeding up the dissipation of bubble kinetic energy.The numerical simulation analysis of the flow field of the flotation column with a column height of 15 m was carried out by applying ANSYS ICEM 19.0software.In case of control scheme by the single spray injector,the kinetic energy of the bubble was at high level in the early stage until the bubble reached the height of 12 m in the column,which is about0.007m~2?s~2.In case of the control schemes by two spray injectors set in opposite,one single spray injector plus energy dissipation plate and rubber microporous aerator,the kinetic energy of the bubble were reduced to 0.003～0.004m~2?s~2 when bubble was at the column height of3 m plate,5.Mineral flotation efficiency in industry can be improved by using spray injector plus energy dissipation plate or using rubber microporous aerator replace spray gun as bubble generator.The on-site molybdenum beneficiation industrial research were carried out in the molybdenum concentrator of China Molybdenum Group.The results of the floating molybdenum roughing test column test show that under the condition of similar raw ore grade and concentrate recovery,by using the control mechanism of spray injector plus energy dissipation plate and rubber microporous aerator,the grade of molybdenum rough concentrate was increased by 5.41%and 8.81%respectively.The results of industrial test on molybdenum ore dressing by using flotation column show that by using the control mechanism of replacing spray injector with rubber microporous aerator,the molybdenum concentrate grade was improved by 2.23%,the accumulation of medium floatable particles in pulp caused by slurry turbulence is reduced and the"cake layer"phenomenon in flotation production is solved.This paper has 88 figures,25 tables,138 references... |
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