Experimental Study On The Effect Of Water Infusion On The Deformation Property And Size Distribution Of Anthracite Coal Samples Under Cqompression

Water infusion is not only widely used for guarding against mine disaster such as coal dust blast,pressure bump,gas and coal outburst,but also used for softening top coal,and improving the caving ability of top coal.So that the Anthracite production enterprises widely fear whether the lump anthracite productivity will reduce.Price of anthracite is much related to block size,the price of coal in small block only has 60%the price of the blocks between 25mm and 80mm.So anthracite lump coal rate have a vital role on anthracite production enterprise economic benefits.It is very necessary that experimental study on the effect of water infusion on the deformation property and size distribution of anthracite coal samples under compression.This article take the Shanxi province Gaoping city Wangyun 3 coal seam for experiment samples.First of all apply the physical and mechanical,thermal and water-chemical analysis of the weakening of coal;second,measured the basic physical properties of coal,coal mechanics characteristic,vitrinite macerals and maximum reflectivity,slit-pore characteristics and wettability of coal and water;third,the contrast experiment of natural water content and water saturated anthracite coal sample which were under controlled compression was performed,the effect of water infusion on the the deformation property and size distribution of anthracite coal samples under compression were studied,and application of fractal theory and Rosin-Rammler model to analyze size distribution of anthracite coal samples under compression;finally,a industrial experiments about the different size distribution of water injection and non-injection coal seam in top coal was performed in Wagnyun coal mine 3#coal seam 3204 and 3203 work face.Some conclusions can be drawn as follows:(1)The Influence factors of weakening of water on coal is:development of coal pores,cracks and distribution characteristics,seam stress,physical and mechanical properties of coal seam,chemical constituents of coal mines,gas pressure of coal,saturated water productivity,coal-water contact angle.These factors affect the weakening erosion of the water on coal,and have important influence for coal under pressure crushing;(2)From the perspective of physical mechanical analysis of the weakening of water on coal,and come to the following conclusion:after the water into the coal,the effective stress within coal body was changed,and reduces the cohesion and the angle of internal friction,making coal more easily broken;(3)From thermodynamic perspective analysis of the weakening of the water on coal,have come to the following conclusion:water into the pores of coal body in and reduced the Gibbs function of coal,reduces coal of strength,increasing breaking levels;(4)From chemical energy perspective analysis of the weakening of the water on coal,and came to the following conclusions:after water into coal,water and minerals,mineral and mineral effect each other,produced energy"transfer",which make the attraction between the lattice of coal lower and make coal more easily broken.(5)By the measurement of coal sample specimens can obtain physical mechanical characteristics of coal sample,bulk density of coal of 3#coal seam is 1.4273g/cm3,specific gravity is 1.5151g/cm3,natural water content is 2.1525/%,atmospheric moisture saturated State is 2.8074%,saturated water content when pressurized 3MPa is 3.0334%,belong to water less increase in coal seams;(6)The compressive strength of natural state is 8.74MPa,the compressive strength of saturated state is 7.41 MPa,softening coefficient is 0.848,and belong to medium to soften of coal seam;(7)For WangYun coal,the largest vitrinite reflectance of specie A of 3#is 2.36%,specie B is 2.37%,the average is 2.365%,belong to anthracite.(8)The results under the microscope observation showed that:3#specimen A,vitrinite is 65.9%,inertinite content is 28.7%;specimens B,vitrinite is 67.8%,inertinite contents is 28.9%.Vitrinite in homogeneous matrix of vitrinite and vitrinite,structure vitrinite,clumps vitrinite and debris vitrinite has appeared,oil-soaked under reflected light is white.Inertinite in.oil-immersed under reflected light is lit in white silk,transition component and white half of silk,slightly coarse grain whoes white spherical particle size is about 10 ? m and silk fragments have appeared.Chitose group does not appear.(9)The mineral content of coal sample mainly for the clay mineral,A specimen accounted for 5.4%,B specimens 3.3%,oil-filled reflection is light black.(10)Wangyun coal mine 3#caving coal in coal mine-like plane fracture of size distribution fractal dimension of 1.5673,on the surface of coal in the region through the length of the crack number is 6.21,and belongs to the Middle fractured seams;(11)From the total porosity,3#coal total average porosity of 5.4019,belonging to the middle porosity seams.From the pore size distribution,3#belongs to the big hole of coal development,total pore volume 46.4%.(12)The peak strength,modulus of pre-peak strength,the linear modulus value of post-peak strength were reduced,the plastic flow characteristics of post-peak was enhanced and the residual strength of coal was improved;(13)The size distribution of anthracite coal sample fractured by compression was changed by water infusion;(14)The size-mass distribution of anthracite coal samples fractured by compression has an obvious fractal characteristics,as well as the fractal dimension of water saturated coal is smaller,the rate of small blocks fromwater saturated samples is reduced,large blocks for sale requirements is increased.(15)As the compression increased,the distribution of natural water content coal tends to disperse,but the distribution of water-saturated coal sample tended to be concentrated,as well the distribution of water-saturated coal sample is more focused than natural water content coal sample.(16)The median diameter d50 of natural water content coal sample is small than water saturated coal,the broken level of water saturated coal sample is more than natural water content coal sample.(17)Advance water infusion in Mining of fully mechanized caving can reduce the number of the large-size lump coals which require specially broken,while improve the number of the middle-size lump coals which meet the high value sales requirements.Summing up the above:the rate of block meet for sale which from Wangyun-coal-mine's fusion meta-anthracite under compression is increase,the rate of the required specially broken bulk is reduce.