Study Of Ultra-low Ash Coal Preparation Using Triboelectric Separation Based On Surface Modification

Preparation of ultra-low-ash coal in which ash content is less than2%as raw materials forthe production of carbon materials, has great significance for improving coal economicadditional value. For its simple device structure, low running cost, low pollution, triboelectrictechnology is of great prospect in ultra-low-ash coal preparation. This topic will focus on studyof ultra-low ash coal preparation using triboelectric separation based on surface modification.Firstly, by measuring the charge-to-mass of clean coal and mineral particles under theconditions of different friction materials, the impact of different friction materials on frictioncharge feature of pulverized coal are explored. The test results show that for the friction charge ofclean coal and all minerals, organic glass and PVC work best, and the heterogeneous chargebetween clean coal and other minerals are bigger. Based on this a triboelectric machine withfolding type friction plate is designed, and PVC is chosen as materials of friction device andorganic glass as the friction plate.Then by measuring the charge-to-mass of clean coal and mineral particles under theconditions of different surface modification, the impact of different surface modification onfriction charge feature of pulverized coal are explored. The test results show that choosingkerosene as the surface modification agent, modifier6000g/t of modification agent and20s asthe modification time range, are the most reasonable modification conditions respectively.Next optimized experimentations of operating parameters of the new designed triboelecticmachine are conducted. We investigate the impact of plate voltage, air volume and feed rate ontriboelectric, and build the mathematical model between cleans ash, yield and the operatingparameters. The optimized experimental results show that when the voltage is controlled in80kV, air flux is about70m3/h and feed rate is about70Hz, the cleans ash and yield can reach thebest. The cleans ash and yield are1.827%and64.54%, respectively.Finally under the condition of optimized operating parameters mentioned above, weexamine the impact of surface modification agent type, the dosage of modifying agent,modification time on triboelectric. The optimized experimental results indicate that when thesurface modification agent is kerosene, the dosage of modifying agent is8000g/t andmodification time is22s, the triboelectric machine works best. The cleans ash and yield are1.763%and64.54%, respectively.And they are verified through experiments.