Study On The Development Of Flow Film And Minerals Migration Law In The Enhanced Gravity Field

The increasing fine grained minerals have brings a huge challenge to the minerals separation.The gravity separation has the advantages of low price and environmental protection.The selection of mineral resources has the advantages of low price and environmental protection.In recent years,the enhanced gravity method developed rapidly in the application of fine-grained mineral selection,extended the lower size of feed materials and improved the utilization efficiency of poor,miscellaneous and fine minerals.The current study of enhanced gravity method mainly focuses on the expansion of mineral species and application in industry,however,the fundamental research on the separation mechanism is hysteretic and cannot meet the requirements of guiding the actual separation process.This average flow film thickness was measured by experiments and constituted the research basis of development law of flow film.Base on the measurement results,the mathematic model between average flow film thickness and rotational frequency were founded.The fundamental dynamics equations from the N-S equation and continuity equation were established by analyzed the force condition of flow film.The dynamic equations were solved by the method of theoretical analysis and numerical simulation.The theoretical analysis results,numerical simulation results and experimental results were compared respectively,and the theoretical analysis results under high rotational frequency and the accuracy of numerical simulation analysis were verified.The development of flow film composed of four stages: fluid filling stage,flow film production stage,flow film development stage and flow film stabilization stage from the study of flow film thickness varied with time and height.The influence of atmospheric pressure on the flow deformation was determined by kinetic analysis of flow film when take the whole flow film as the research subject.The deformation of the "concave" type of flow film were revealed through the macroscopic hypothesis analysis.The function of flow film in delamination area under different rotational frequencies were analyzed by the development law of flow film thickness.The fluid source of separation area were determined by analyzed the structure of separation groove.By introducing analysis method of the circular turbulent jet,the basic dynamics equation of the fluid in separation area was established.The distribution characteristics of flow field,tangential velocity and axial velocity were also studied.The force of particles in the separation zone was analyzed.Dynamics equation of particle motion in the radial and axial direction at axial cross section was established to obtain the velocity and displacement expression of particle in the radial and axial direction,respectively.The migration characteristics of pure quartz in the enhanced gravitational field was studied based on the continuity of the particle size.The effect law of backwater pressure and rotational frequency on the enrichment state of each graded fraction in the overflow and underflow was analyzed.Relative to the significantly migration characteristics of coarse grained materials,0.074-0.045 mm and-0.045 mm graded material had the effect of interference mismatch in the separation process.Material deposition,material separation and material retention were three migration stages in the separation space of quartz.Classification effect in the gravitational field was studied,and its inefficiency was validation.Materials separation test at unit time was designed for the reveal of particles stability-instability mechanism in the separation zone.Based on the continuity of density,particle size of fine high sulfur coal,the migration characteristics of high sulfur coal was studied in the enhanced gravitational field.Narrow fraction material separation test were carried out to determine the testing scheme of grinding-wet screen-centrifugal separation and to clear about the size range for Falcon separation.With backwater pressure and rotational frequency as factors,the influence law on the product distribution and the migration patterns of fine high sulfur in the enhanced gravitational field,which set ash content and sulfur content as representative indicators,was analyzed in detail.The backwater pressure had coarse adjustment function on the yield,ash content and sulfur content of products,while the rotational frequency had fine adjustment function.