Effect of microwave irradiation on the grinding characteristics of Ximeng lignite

The grinding characteristics of untreated and microwave-treated Ximeng lignites (XLs) were investigated, and the effects of microwave irradiation time, particle size range, and initial moisture were studied. The mass fraction and particle size distribution of the fine ground product with < 0.154 mm particle size range of untreated and microwave-treated XLs were obtained. According to the analysis results of proximate, scanning electron microscopy and nitrogen absorption, the dominant mechanisms that improved the grindability of XL with high moisture under microwave irradiation included the rapid removal of moisture within the XL and the destruction of the pore structure induced by the steam jet flow generated with moisture removal. Microwave irradiation could improve the grindability of XL with high moisture, thus increasing the breakage rate of microwave-treated XL and mass fraction of the fine ground product significantly. The particle size distributions of the fine ground products of untreated and microwave-treated XLs changed slightly. With increasing microwave irradiation time, initial moisture, and particle size range of XL, the increment in the grindability of microwave-treated XL increased. When XL was treated at low microwave power, the microwave irradiation time was extended properly to avoid the accumulation of moisture on the surface. Therefore, the grindability of microwave-treated XL improved significantly.