Study On The Effect Of Pressurized Dewatering Of Coal Slurry And The Regulation Of Compressibility And Pore Structure Of Filter Cake

Coal slurry dewatering is one of the important guarantees for the sustainable development of coal beneficiation production.With the decrease of high-quality coal resources and the development of coal mining mechanization and intelligence,fine coal slurry is increasing and the quality of raw coal is deteriorating,so coal slurry dewatering has become a bottleneck problem in the coal beneficiation industry.Pressurised dewatering is a common dewatering method in the coal processing industry.In-depth research on the influencing factors and regulation methods of the effect of pressurised dewatering of coal slurry,revealing the mechanism of filter cake compressibility and pore structure optimisation,and realising efficient dewatering of fine coal slurry are important for promoting the recycling of water resources and tailings resources and the self-developed new pressurised dewatering effect intelligent monitoring test device industry "carbon emission reduction " It has important practical significance.In this paper,using the independently developed new pressurised dewatering effect intelligent evaluation device,the orthogonal test method,SPSS software,extreme difference analysis and analysis of variance(ANOVA)are used to analyse the law and significance of the influence of pressure,feed concentration and particle grade composition on the dewatering of coal slurry water.The effects of three skeleton builders,namely perlite,α-hemihydrate gypsum and diatomaceous earth,and two surfactants,alkylphenol ethoxylate(OP-10)and nonylphenol ethoxylate(TX-10),on the pressurized dewatering and filter cake compressibility of coal slurry were investigated by using comprehensive evaluation indexes such as pressurized filtration speed,filter cake thickness,filter cake moisture,compressive dewatering index,average mass specific resistance and capillary water absorption time.The effects of the surfactant filtration aids on the pressurized dewatering and cake compressibility of the coal slurry were analyzed by X-ray computed tomography(X-CT)and wetting heat tests.The main conclusions are as follows.(1)The sequence of factors influencing the coal slurry filtration process was studied.Within the range of 0.2-0.4 MPa pressure,200-600 g/L feed concentration and-0.045-0.5 mm particle size composition,the significance relationship is that particle size composition > feed concentration > pressure,and particle size composition is an important factor affecting coal slurry dewatering.The optimum design of coal slurry water dewatering is thus obtained,with the best solution having a filtration pressure of 0.6 MPa,a coal slurry feed concentration of 200g/L,and a particle size composition of 0.045-0.125 mm,when the dewatering speed is the fastest,with only 34.5 s required to enter the compressive dewatering stage,a minimum cake thickness of 2.924 mm,and a strong compressibility of the filter cake.The minimum Compression Dehydration Index(CDI)is only 3.59.(2)The effects of the three skeletal constructs on the dewatering effect of coal slurry were compared.Perlite basically failed to improve the filtration speed,α-hemihydrate gypsum slightly improved the filtration speed,and diatomaceous earth significantly improved the dewatering performance of coal slurry water.The filtration aid effects of 2 surfactants OP-10 and TX-10 were compared.Both surfactants had good filtration aid effects on the samples extracted from the bottom flow of Malan concentrator,and compared with the results of the blank test,when the agent dosage was 200 g/t,OP-10 could reduce the filter cake moisture by3.75%,double the filtration speed,and the CST reduction rate was the largest,and the compression dewatering index was small.(3)The three stages of the filter cake forming process were obtained through the analysis of the pressure-deformation relationship of the filter cake,and it was found that the compression dewatering stage was closely related to the dewatering effect,and the compression dewatering index CDI was further defined.147.18 and 155.35 respectively.(4)Through CT scanning technology,the three-dimensional pore structure can be obtained by using Avizo software,comparing the dewatering effect of three skeleton constructs and two surfactants on coal slurry,microscopically analysing the dewatering effect of the original sample and OP-10 added at a concentration of 200 g/t.The effective porosity can be obtained by the corresponding computing module when adding OP-10 at a concentration of 200 g/t is20.43%,with good connectivity,while the effective porosity of the original sample is 11.96%,with poor connectivity and a large proportion of isolated pores,making filtering and dewatering difficult.The analysis shows that the tortuosity of the original sample and OP-10 is 2.37 and1.9 respectively,the larger the porosity of the filter cake with OP-10,the lower the tortuosity,the higher the permeability of the filter cake,the lower the average specific resistance and the faster the filtration speed.