Study On The Separation Theory And Application Of Coarse Flotation Column Regulated By Flow Field

In production practice,the flotation recovery of coarse particle metal minerals（+150μm）has always been one of the technical difficulties in mineral processing field.In conventional flotation machine,the rotational speed can be increased to increase the collision probability of bubbles and coarse particles,but at the same time,it will also increase the probability of coarse particles falling off in the bubble-particle aggregate in the pulp,and the improvement of the flotation effect of coarse particles is very limited.In this paper,a new three-stage flotation column for coarse particles with independent intellectual property rights is developed by combining fluidization technology with flotation equipment.The distribution characteristics of the flow field in the cylinder and the distribution law of the bubble group are systematically studied.The flotation test of small coarse particles in the laboratory is completed,and the semi-industrial test and application research are carried out.The flotation recovery of-1 mm coarse-grained molybdenum ore and-0.45 mm coarse-grained copper ore from cyclone sedimentation and tailings has been successfully achieved in Xinyuan molybdenum mine of Fengning and Dexing Copper Mine of Jiangtong Group in Hebei Province,respectively.Flotation of coarse particles can not only relieve grinding pressure,save energy and reduce consumption,but also benefit the resource utilization of coarse particles lost in tailings.The research results of this paper have a certain reference value for the development of new technology and new equipment for high efficiency separation of coarse particle minerals.The main conclusions of this paper are as follows:（1）The fluidization behavior of coarse particles in the rising flow of flotation column is illustrated.According to theoretical calculation,in the process of fluidizing flotation,the relatively stable flotation environment and the lifting of bubble-particle aggregates by the drag force of rising water are the key to increase the upper particle size limit of flotation.In this paper,by constructing a CFD multiphase flow model under the Euler framework,the modified Gidaspow and Hulin-Gidaspow drag force models are used to predict the fluidizing behavior of irregular particles.The research shows that the apparent flow velocity can be directly used to regulate the axial velocity of particles in fluidizing flotation,so as to control the fluidizing characteristics of particles.（2）The influence mechanism of the flow field characteristics in the three-stage flotation column on the flotation effect of coarse particles was revealed.The Euler-Euler model,RNG k-?turbulence model and CFD-PBM coupling model were used to simulate the flow field distribution in the three-stage flotation column.By adding a stabilizer plate,the turbulent kinetic energy and turbulent dissipation rate of the fluid in the coarse particle flotation column were significantly enhanced,and the uniform distribution of turbulent kinetic energy,turbulent dissipation rate and liquid phase velocity was promoted.The flow field distribution in the flotation column can be significantly improved by using four symmetrical jet tubes for inlet water and bubbles.In the region below the stabilizer plate,the flow velocity has a great influence on the turbulent dissipation rate,and the maximum value is 0.35 m2/s3.However,in the region above the stabilizer plate,the turbulent dissipation rate is less than 0.0001 m2/s³,decreasing by a factor of one thousand.This cascade distributed turbulent dissipation rate is conducive to the three-stage fluid environment of bottom turbulent mineralization,middle turbulent-steady flow transition and upper static fluid flotation,which is conducive to the flotation recovery of coarse particles.（3）The size and distribution of bubbles in the three-stage flotation column were proved.By using the dynamic measurement system of high speed camera and Python code,a large number of bubbles are analyzed statistically.Through the bubble size dynamic measurement system of high speed camera,a large number of bubbles were statistically analyzed by using Python code.The high speed jet is used to generate negative pressure to suction air and generate bubbles.When the air compressor is in the natural aspirating state without additional inflation,the gas-liquid ratio is about 1:3～1:2.5,and the number of bubbles reaches the maximum.When the gas-liquid ratio is greater than the natural inspiratory state,it is necessary to supplement gas to the bubbler.At this time,the bubble diameter distribution gradually changes from a peak to a gentle peak,the number of large bubbles increases,and the total number of bubbles decreases.The addition of foaming agent can significantly reduce the bubble size distribution range and reduce the average size.The bubble size distribution characteristics in fluidizing flotation column can be described by lognormal distribution function,and the relationship model between bubble Sauter diameter and rising water quantity Q_l,aeration volume Q_gand foaming agent concentration P was established:d₃₂=1.884Q_g^0.638Q_l^-0.416P^-0.49.The equation shows that the bubble Sauter diameter is positively correlated with the aeration volume and negatively correlated with the rising water volume and the foaming agent concentration.（4）A new three-stage flotation column for coarse particles was developed.Starting from the principle of fluidization technology,the flow field characteristics of flotation equipment and the feasible structure design,the coarse particle flotation column is designed by using the three-stage structure,which organically combines the turbulent mineralization zone,the stable flow transition zone and the static selection,so as to provide the best flow field environment for the flotation of coarse particles.（5）The experimental effect of the new coarse particle flotation column is verified.The coarse particle flotation column built in the laboratory was used to carry out flotation tests on the pure minerals of chalcopyrite and molybdenite as well as the mixed minerals with quartz,and a good separation effect was obtained.On the basis of laboratory tests,designed and processed theΦ200×900 mm semi-industrial test prototype of 1.0t/h,and carried out semi-industrial tests in Hebei Fengning Xinyuan molybdenum mine and Jiangtong Group Dexing Copper mine,on the one hand,the abrasive particles in the grinding-classification loop in the cyclone sediment can be removed in advance,greatly reducing grinding energy consumption;On the other hand,the coarse-grained minerals lost in tailings can be recovered effectively,and the overall recovery of copper and molybdenum can be significantly improved.The application of the new equipment not only creates more economic benefits for enterprises,but also greatly improves the comprehensive recovery level of large-scale copper and molybdenum ore resources,which can provide strong technical support and demonstration for similar enterprises to develop and utilize.86 Figures,29 Tables,172 References...