Study On Liberation And Crushing Of Middlings Of Scarce Coke Coal

Coking coal and fat coal are very valuable and scarce resource,but at present,there is a kind of phenomenon that many coal washery treat middlings as power coal.Not only waste resource but also pollute the environment. In order to recover the coking coal resources, the dissociation of coal and gangue should be the primary condition Selecting Qianjiaying coal washery as the research object,this paper studied middlings of dense medium cyclone and vertical lifting wheel separator with New verticle crusher,observe the crush effect,and compare with jaw crusher.Analy the density composition and size composition of coarse middlings and powder middlings.By analyzing the size composition,we find that the perform of vibrating screens is well;By analyzing the density composition, when the cleans coal ahs is 10.5%,the theoretical value of corase middlings is 3%,it is haded to further dissociated. Using XRF and XRD,we studied the coal elemental composition and mineral composition.Due to the differences of hardness in coal and gangue mineral, it`s possible to be selective broken, and the impact crusher is the most beneficial way to selectively broken, but the impact crusher is suitable for larger size materials. Therefore, it has to design impact crusher as coarse crushing section, shear crusher as fine crushing section to produce a finely granular material. The device structure includes: inlet, fixed jaw, rotary crushing jaw, national crushing disc, rotary crushing disc, coarse crushing and fine crushing machine; working principle:coarse-grained material through the inlet into the device crushing section, carried out in the rotation speed impact crushing jaw crushing operations, the crushed product into the crushing section, acting between the rotating disc and fixed disc crushing shearing force generated crushing operations, the crushed final product of centrifugal force and rotation negative pressure disc and fixed disc relative movement into the hopper. By the test of motor speed,we confirm the frequency of coarse crushing is 50 Hz,the powed crushing is 50 Hz,the feed is 80kg/h. By the size test,the smaller the size of particle is,the lower the yield.Experiment of diffierent crushing limit : By the new verticle crusher,Middlings was broken into small particles of different sizes,like 6mm, 3mm and 1mm,then,it is be screened,float-sinked, and find the relationship between size and slime crushing yield and clean coal yield.The contrast of new verticle crusher and jaw crusher :When broken into the same size,by the density analysis and size analysis,we find that the yield of-0.5mm is lower with new verticle crusher,on other words,the over crushing is more serious when useing jaw crusher.In the meantime, with new verticle crusher,the yield of clean coal can be 2-3 percentage points higher than jaw crusher.Abrove all,the new verticle crusher is better than jaw crusher,but dissociation degree is not enough,it need to be grinded further.There is a phenomenon that the shape of the product is flat and is not fit for high hardness materials.