Study On The Liberation-Flotation Separation Technology Of Flotation Middlings Coal From Kailuan Mining Area

With the quality of coking coal declining,the Flotation middlings coal with medium-high ash content is gradually characterized by high yield and intergrowth content.Re-separation of flotation middlings coal directly affects the quality and quantity of clean coal products and the research on separation process plays an important role in coal separation technology and efficient utilization of scarce coal resources.However,the fine sorting of flotation middlings coal is every difficult due to that the particle size of flotation middlings coal is between the lower limit of gravity separation and the upper limit of flotation separation,high intergrowth content and close flotation close.In view of above problems,from aspects including rapid liberation of middlings coal and particle size control,process intensification test of liberation products with close flotation close and efficient separation process,flotation middlings coal from Tanshan Kailuan mine characterized by extreme difficulty in separation was taken as research sample,and liberation-flotation separation process of flotation middlings coal was systematically studied.The findings are as follows:Physical properties of flotation middlings coal were studied.The size composition of flotation middlings coal is coarse coal and mostly exists in the of intergrowth;its ash content is up to 49.30%,which contains a lot offine mud with high ash content,but there are also some low ash content materials in flotation middlings coal whose floatability is extremely difficult.The overgrowth ratio of mineral and organic matter is up to 78.23%,and the relative content of clay mineral is nearly 70%.The clay minerals are disseminated and filled with organic macerals,which increases the difficulty of middlings coal liberation.The effects of pre-removal of high-ash materials by gravity separation on the quality characteristics of flotation middlings coal were studied.The flotation middlings coal was separated by a spiral separator,and the the raw coal with high ash content was discarded,which provided a suitable raw material for subsequent middlings coal liberation.The ash content of coal was reduced from 49.30% to 26.50% and the yield was about 46.28% after discarded by gravity separation under the parameters of handling capacity 0.25t/h and pulp concentration 25%,respectively.The theory of coal yield is about 61% when the required coal ash is 12.5% after tailings discarded by gravity.The rapid middlings coal liberation and particle size control of flotation middlings coal were studied.It is determined that the flotation middlings coal is more suitable to begrinded coal feed by comparing the liberation characteristics of magnetic preparation of tailings,flotation tailings and flotation middlings coal;The particle size control experiment shows that the results of closed circuit non-graded coal grinding is better than that of open circuit grading coal grinding,and the balance between fineness and flotation granularity is better.When the filling rate of the rod mill is 17%,the closed-circuit non-graded coal d50 and d80 are 0.09 mm and 0.24 mm respectively,and the particle size distribution is in the range of better flotation granularity.The qualified coal yield is 36.50%,about 15% higher than that of open grade coal grinding.The process intensification test of liberation products with iso flotation close was studied.The optimum experimental parameters were obtained under the condition of rough separation and cleaning separation for the liberated flotation middlings coal,and it was founded that the contradiction between the yield of clean coal and coal ash are mainly caused by non-selective floating of intergrowth after liberation and the clay micro-particles.The new type of collector of H708 and H707 were used to intensify the process of flotation middlings coal based on the inhibition of clay minerals and the activation of coal particles.The recovery rate of coal combustible is increased by more than 15 percentage points,and the flotation index is more stable,which highlights the superior selectivity of the new pharmacy when reagent dosage reduced by about 40%,compared with diesel and fusel reagent in flotation.The separation process of tailings discarded by gravity,rapid middlings coal liberation and high efficient flotation was proposed.High ash material in flotation middlings coal was pre-removed by gravity.And flotation middlings coal was then introduced into the two-stage column for separation after rapid liberation.Combined with clay mineral suppression and coal particle activation efficient flotation reagent,the process can adapt to the change of different materials and be flexibly adjusted to meet product requirements.The experimental results show that the separation process can obtain the ideal index: cleaning coal with 12.32% ash content and about 31.12% of yield.