Study On The Technical Refurbishment And Coarse Slime Separation Process Of Coal Preparation Plant Of Huangling No.1 Coal Mine

According to the ‘National Plan for Coping with Climate Change(2014-2020)',by the end of the 13 th Five-Year Plan period,coal will share 60% of total China energy consumption,while figures for crude oil and natural gas are 20% and 7% respectively,and the other 13% is contributed by renewable energy resource.Although authorities endeavor to improve the proportion of the use of renewable energy by applying multiple national level policies,it is safe to predict that,in the coming decades,coal will remain dominated energy resource in its total energy consumption in China.During the 13 th Five-Year Plan period,high efficient clean coal utilization is promoted by the state.It is well known that coal preparation processing is an effective approach to achieve clean and efficient usage of coal resource.Coal preparation process design is the key for a Coal Preparation Plant(CPP),and the gravitational coarse slime separation is an important part in a sound preparation process.The CPP plant of Huangling No.1 Coal Mine is a large coking coal CPP,with a 6.0 Mt/a operational capacity.The raw coal feed is gas coal,and multiple separation processing are applied in this plant.More specifically,the free-feed three-products dense-medium cyclone is chosen to process size range 50-0.5mm,while 0.5-0.25 mm coarse slime and-0.25 mm slurry are separated by slime dense-medium cyclone and mechanical flotation machines respectively.Correspondingly,products are fine coal,middling coal,coarse slime and gangue.Main product is the final fine coal which is consisted by dense-medium fine coal,coarse fine coal and floatation fine coal.During years of production,it was found that the coarse fine coal normally contains a higher ash content(around 15%)compared with other two streams,and the amount of ash is unstable.In order to maintain the designed specifications of the final fine coal product to meet the market's requirements,the free-feed three-product dense-medium cyclone and the floatation machines have to operate at a lower separate density,which leads to a lower fine coal recovery rate in these two operation units.Because of this the total average fine coal recovery rate in production is 68.5% lower than the designed value(71.72%).In order to determine the root causes of this problem,this study has conducted the screen classification and float-and-sink analysis.The results of these experiments indicate that the dominated the secondary size ranges in coarse slime(from magnetic separation tailings of fine coal)are +0.5mm and 0.5-0.25 mm respectively,and ash contents for both two ranges are lower than 30%.Therefore,a larger a large amount of low ash content coarse fine coal can be recovered by adopting effective coarse slime separator,and this action is very likely to generate considerable economic profits for Huangling No.1 Coal Mine.After comprehensive comparisons on the different coarse slime processes,the update plan finalized as using Teetered Bed Separator(TBS)to handle size range 0.5-0.25 mm while keeping the existed free-feed three-product dense-medium cyclone and floatation separator to process size range 50-0.5mm and-0.25 mm slurry respectively.This combination can make the most of advantages of each separator,and this will bring a maximum fine coal recovery.Meanwhile,this system is highly automatic and reliable,which means a minimum requirement for manual operation and maintenance.