Experimental Study On Microwave Coking Of Coking Coal Blended With Coke Powder

China is rich in coal resources.However,high-quality coking coal reserves are limited.Therefore,coal blending coking process is used to reduce the production cost.Coke powder,as a by-product of coking,has a wide range of sources,high carbon content and good dielectric properties.The traditional coking process has the disadvantages of long coking time,low energy utilization rate and high maintenance cost.Therefore,the research and development of new efficient and clean coking process has become a necessity in the field of coal coking.In order to increase the efficiency of heating requirement involved in coking process,microwave heating was used.This heating method has the characteristics of fast heating speed,high energy utilization and low running cost.Therefore,it is of practical and theoretical significance to study the co-coking technology of coking coal and coke powder under microwave heating.In this paper,a self-designed microwave coking reaction device was used to systematically study the influence of coke powder ratios,microwave heating rate and sample bulk density on coke quality during co-coking of different kinds of coking coal(CY coking coal,ML fat coal,RN gas coal and BG blended coal)and coke powder mixture.The microwave coke quality was investigated using customized laboratory particulate coke reactivity index(PRI)apparatus,also a customized coke structure strength and micro strength tester,specific surface area analyzer(Brunauer Emmeit Teller,BET),scanning electron microscope(SEM)and X-ray diffraction(XRD)characterization methods such as analysis of the chemical and physical properties of microwave coke,and with two business cokes(CC1 and CC2).The experimental results showed that with an increase in the coke powder proportion,RN gas coal and BG blended coal microwave coke of PRI reduced.In all four coal samples,the microwave coke mechanical strength reduced gradually,and also the wider stomatal aperture distribution,the stacking height of microwave coke Lc,aromatic lamella maximum number N accumulation,aromaticity fa and aromatic carbon layer of the aromatic ring number n all showed a gradual increase trend while the graphitization degree increased.With the speeding up of the microwave heating rate,the RN gas coal coke's PRI is reduced,while the other three coal coke's PRI only had little changes,and all four kinds of coal sample microwave coke mechanical strength decreased,while the wider stomatal aperture distribution and small porosity increased.CY coking coal,ML fat coal and RN gas coal,three microwave coke's graphitization degree showed an increased trend.Samples with the mixture of coal and coke powder bulk density increased,the CY microwave coke due to its stronger bond ability,the PRI rose slightly.ML fat coal,RN gas coal and BG blended coal's coke showed a downward trend in CO2 reactivity.All four coal samples microwave coke's mechanical strength gradually increased,in addition,the coke stomatal narrowpore size distribution,pore wall strength also increased.From the XRD result,it was observed that the bulk density's change has different influence on the four samples coke's microcrystalline structure.In conclusion,the optimal coke powder mixing amount of each coal sample is different.The higher the microwave heating rate,the lower the energy consumption of coking.Higher pile density led to a coke with higher strength.By comparing various data of microwave coke and commercial coke,it was found that the heating rate had little effect on the coke quality.Considering the utilization of coke powder and energy cost,the most suitable proportion of coke powder for CY coking coal and ML fat coal was 20% while for BG blended coal it was 10%.The optimum condition required for all samples were bulk density of 0.85g/cm3 and the heating rate of 20 o C/min.The quality of microwave coke can be compared with the same quality as commercial coke.This indicates that microwave coking coal blended with coke powder is feasible.