Optimization of the Separation of Unburned Coal from a Selected Fly Ash

Unburned coal grains often hinder the economic utilization of fly ash and also represent energy loss of the fuel. This paper addresses the possibility of separating unburned coal from a selected fly ash with typical mineralogical and chemical characteristics. To assess the possibility of separating the unburned coal, the analysis of the grain density and composition of ash was used. The unburned coal was separated using one wet gravity and three dry methods. The highest amount of unburned coal, 62% in the concentrate, was obtained using the fluidized bed method with separation. The largest weight yield of concentrate equal to 17.8% was obtained using the electrostatic method.

Analysis of the forms of wear and durability of the abrasive films

The paper analyzes the wear and durability of abrasive films designed for microsmoothing produced by electrostatic method. In order to carry out tool wear studies, a microgrinding process was performed using an abrasive film with a nominal grain size of 15 μm. The next step was the study, using scanning microscope. Crushed grains were observed on the surface of the foil, overflows, and extremely high temperatures in the treatment zone, above 1400°C, which resulted in the formation of spherical chips.