Development And Application Of Fine Coal Intensive Shear Pulping Equipment

Froth flotation is one of the most effective methods for processing fine coal slurry.However,with the increasing level of mechanization in coal mining and the decrease in the availability of high-quality raw coal,the characteristics of fine-grained and highash content of the flotation feed have emerged.For the flotation process of fine-grain high-ash coal slurry,pulp conditioning is an important part of it.The appropriate pulp conditioning process can greatly reduce the consumption of flotation reagents and optimize sorting indicators.Traditional pulping equipment struggles to achieve high levels of drug dispersion and efficient collisions between drugs and particles.This research project focuses on the study of the flotation coal slime at the Guotun coal preparation plant of Shandong Energy Linmei Group.The project aims to develop and apply equipment for strong shear mixing of fine-grained and high-ash coal slime,optimize the flotation process,and achieve the strategic goal of "production without coal slime" required by the coal preparation plant.Firstly,the diagnostic analysis of the flotation system at Guotun Coal Preparation Plant revealed that the main factors causing excessive ash in the flotation concentrate were the problems of coarse particles escaping and fine particles entrapping.This may be due to poor pulping efficiency of the slurry conditioning tank,making it difficult for coarse particles to suspend and collide with reagents,resulting in a large amount of lowash coarse particles entering the tailings and causing the "escaped coarse" problem.Additionally,poor shear performance of the slurry conditioning tank caused high-ash fine mud to disperse poorly and easily cover low-ash coal particles,causing entrainment in the flotation concentrate and leading to the "entrapped fine" problem.Particle size and density analysis of the flotation feed and concentrate was conducted to reach these conclusions.Then,a strong shear pulping process was designed to couple a rough and a fine flotation process.By comparing the effects of strong shear pulping and regular pulping in flotation tests,it was found that the former significantly enhances the capturing performance of collectors.Under the same dosage of reagents,the strong shear pulping process can reduce the ash content of fine coal by 4% while maintaining similar coal recovery rates.Additionally,it can increase the ash content of the tailings by 10%,indicating that the strong shear pulping process can effectively improve the quality of fine coal flotation and increase flotation efficiency.The CFD simulation of the internal flow field characteristics in the strong shear pulping barrel showed that the fluid frequently passes through the circulation hole of the shear plate between the agitation chambers and the turbulent dissipation rate is high between the gear plate and the baffle,resulting in strong fluid shear forces.This indicates that the design of the serrated shear plate is reasonable and can effectively shear the mineral slurry,enhancing the mixing performance of the serrated disc turbine pulping barrel.Last,a multi-segment strong shearing pulp bucket with a serrated structure was designed and industrial flotation tests of strong shearing pulping were carried out.It was found that introducing strong shearing pulping technology can greatly improve the flotation process effect on site,with the flotation yield of clean coal generally increased by 10%-30% and the ash content of tail coal increased by 4%-24%.Particle size analysis of the strong shearing pulping clean coal products revealed that the combustible recovery rate of each particle size grade of the shearing pulping flotation clean coal is overall ahead of the ordinary pulping flotation clean coal,and under the optimal conditions,the combustible recovery rate of each particle size grade is increased by 20%-40%.Optimization tests of the drug system of the strong shearing pulping flotation process found that the dosage of the collector reaches saturation at 680g/t,while the dosage of the foaming agent has a greater influence on the flotation effect of the strong shearing pulping process,with the flotation effect being better at a dosage of 85-102 g/t.Within this range,the ash content of the selected clean coal in one compartment can reach 9.04%-10.22%,and the ash content of the coarse tail coal can reach 57%-65%,which meets the process design standards of the coal preparation plant.