Comparisons of dry grinding kinetics of lignite, bituminous coal, and petroleum coke

Abstract

The objective of this study was to analyze dry grinding kinetics of three different solid fuels in terms of selection and breakage distribution functions values using a batch laboratory ball mill. For this purpose, first, standard Bond grindability tests were made for three different fuel samples. Second, experiments were carried out with eight different mono-sizes between 1.7 and 0.106 mm formed by a √2 sieve series fraction. Then, parameters of Si and B i,j equations were determined from the size distributions at different grinding times. Finally, the kinetic model parameters (Si , aT , α, γ, β, and φ j ) were compared for three different fuel samples, and the relationship between proximate analysis values (ash, moisture, etc.) with the Bond grindability value (Gbg ) and breakage parameters were examined. From the results of the test, the validity of the relationships between Bond grindability and proximate analysis has been not confirmed with good correlation coefficients. The reason for this negative result could be attributed to a difference of the geological origin of solid fuels. However, relationships between breakage parameters of grinding kinetic and proximate analysis values of solid fuel samples were obtained for γ value. Additionally, it was found that the bituminous coal was easier to grind than lignite and petroleum coke, taking into account the quite different values of the model parameters. However, petroleum coke was given finer than other fuel in respect to finer size fraction.