Research On The Influencing Factors Of Lignite Flotation And The Synthesis And Performance Of Coal Water Slurry Dispersant

My country's low-rank lignite reserves account for about 20%of the country's coal reserves,untreated low-grade coal has a low utilization rate due to its high volatility,high ash content,low calorific value and heavy pollution.It brings great challenges to resource development and environmental protection.The green and high-efficiency utilization of lignite has important economic and ecological significance to the clean coal resources of our country.Coal flotation is one of the most effective methods for processing fine coal.Lignite,as a low-rank coal,has more oxygen-containing functional groups on the surface,higher content of coal gangue,and larger porosity and specific surface area.Conventional flotation agents cannot effectively increase the recovery rate of lignite and reduce the ash content of clean coal.In addition,the utilization rate of lignite resources is low,and direct combustion causes serious environmental pollution.In this paper,according to the structural characteristics of lignite,different types of flotation reagents are selected,through their screening and compounding,and other factors that improve coal quality during the flotation process are explored,and finally a new and efficient flotation reagent for lignite is developed.After flotation,a new type of coal-based liquid fuel,mainly lignite,is prepared,and a road to efficient and environmentally friendly use of low-rank coal was developed.The conclusions of this paper are as follows:1)Raw coal particle size analysis:Screen coal samples of different particle sizes,use Fourier infrared spectroscopy and XPS element analysis to characterize the surface of the coal sample,and find the best flotation particle size range of 0.125-0.5mm through the ash content and yield of the raw coal.2)The influence of metal ions on lignite flotation:Water quality has an important influence on coal flotation.This paper studies the influence of water with different hardness on coal flotation.Through the comparison of clean coal recovery rate and ash content,it is found that Ca²⁺and Mg²⁺ions in lignite slurry can change the flotation efficiency.3)Screening of flotation reagent formulations:According to the chemical structure of flotation reagents,using the different structural characteristics of hydrophilic and hydrophobic groups to explore the influence of surfactants on the surface properties of coal.Using diesel as a collector a combination of sec-octanol and dipropylene glycol methyl ether as a foaming agent,the coal ash content after flotation was reduced from 19.5%to 10.3%,and the combustible gas recovery rate reached 83.65%.4)Preparation of flotation clean coal water slurry:Washing oil is an important fraction of coal tar,similar in structure to coal.In this study,a kind of coal water slurry dispersant was prepared by modifying the washing oil with sulfonic acid.Fourier infrared spectroscopy,contact angle measurement,surface tension measurement and adsorption test are used to characterize the dispersant,and to explore its dispersing mechanism for coal water slurry.The experimental results show that the adsorption of the dispersant on the coal surface is consistent with the Langmuir monolayer adsorption.Through electrostatic repulsion and steric hindrance,the suspension stability is significantly improved.When the concentration of the washing oil sulfonate dispersant is 0.3%,the Zeta potential,suspension and apparent viscosity of the coal water slurry are-42m V,88.52%and 585m Pa·s,respectively,which meets the national standard requirements of coal water slurry.