Study On Optimization Of Coal Slime Separation And Recovery Process In No.8 Mine Coal Preparation Plant Of Pingdingshan Tianan Coal Mining Company

Coal slime is the by-product of coal mining and processing,which has the characteristics of high microfine particle content,high ash content and high viscosity,making separation and recovery more difficult.The coal slime separation and recovery system of No.8 Mine Coal Preparation Plant of Pingdingshan Tianan Coal Mining Company has long suffered from high ash content of clean coarse slime from tailings of clean coal magnetic separator,low ash content of flotation tailings,and high moisture content of flotation clean coal product.In this thesis,the above problems are investigated,and the test results and domestic coal processing plant renovation experience are integrated to provide a process optimization renovation plan for the coal slime system of the coal processing plant,in order to achieve the purpose of efficient coal slime separation and recovery.Samples from the coal preparation plant were analysed to indicate that the content of-0.25 mm fine particles in the tailings of clean coal magnetic separator is as high as67.60%;the classification efficiency of classifying cyclone is low,and the effect of sieve bend and linear vibrating screen in desliming is poor,resulting in the ash content of the clean coarse slime on the screen exceeding the standard;the ash content of the flotation tailings is low(51.93%),resulting in the loss of coal resources;The content of-0.074 mm fine particles in the flotation clean coal is high(66.31%),resulting in poor dewatering effect of pressure filter and flow-through filter press,the average moisture of the filter cake exceeds the standard,the electricity consumption and cost of the dewatering equipment is high.In response to the above problems,tests and investigation were carried out from the perspective of optimising the particle size composition of the classifying cyclone feed,changing high-efficiency desliming equipment and optimising the fine coal slime flotation and dewatering process.The size composition of the classifying cyclone feed was improved by blending TBS overflow into the tailings of clean coal magnetic separator.The test results of the laboratory classifying cyclone show that the classification efficiency is increased by up to 9.41 percentage points after blending,and the content of-0.25 mm fine particles in the overflow is reduced by up to 26.83 percentage points,and the proportion of TBS overflow blending in the classifier cyclone feed is determined to be 20% after comprehensive test results and the condition of the coal processing plant;the investigation on desliming equipments shows that stacked-type fine screen has significant effect in desliming and ash reduction,and can replace the sieve bend and linear vibrating screen.The results of the flotation test of coal slime show that it is difficult to obtain qualified clean coal and high ash tailings(ash >65%)at the same time by first-stage flotation through flotation machine,The flotation column first-stage flotation process,"flotation machine + flotation machine" and "flotation machine + flotation column" secondary flotation process all can obtain qualified clean coal and high ash tailings.According to the test results and conditions of the plant,the secondary flotation process of " flotation machine primary flotation + flotation machine secondary cleaning " was selected as the optimized solution for fine coal slurry process;the test results of flotation clean coal dewatering showed that by adding filter aid to the flotation clean coal or mixing with clean coarse slime of TBS,the filter cake moisture can be effectively reduced and the cake formation time can be shortened.Combined with the test results and cost analysis,the flotation clean coal blending method was chosen to optimise the flotation clean coal dewatering process,with the maximum proportion of clean coarse slime of TBS blending being20%.The main production index data after the optimisation shows that the classification efficiency of classifying cyclone is increased from 51.90% to 66.70%,which improves the problem of "pinching fine" in the underflow;the ash content on the screen of the stacked-type fine screen is reduced to 10.30%,which has a more obvious effect of desliming and ash reduction;The secondary flotation process works well and can obtain qualified clean coal and high ash tailing coal(69.78%)at the same time;the average moisture of the filter cake of flotation clean coal is reduced to 16.94%,and the operating conditions of dewatering equipment are obviously improved.The quantitative test results of each production index after the renovation show that: the ash content of clean coarse slime has reached the ash content requirement,the ash content of the flotation tailings has been improved,and the dewatering effect of the flotation clean coal has been improved.The economic benefit analysis shows that the annual economic benefit is increased by RMB 51510,900 after the renovation,and the economic benefit is increased significantly.