Optimization of operating conditions on ultra-fine coal grinding through kinetic stirred milling and numerical modeling

This study investigated ultra-fine coal grinding performance of four low-to moderate-cost grinding media in a laboratory stirred mill. Kinetic grinding tests showed that silica beads generated the finest product size with a P-80 of 5.9 pm from a feed size of 24.4 pm while having a specific energy (SE) input of 309 kWh/ton. Nonetheless, the least energy consumption of 109 kWh/ton was achieved by alumina beads; however, yielding a coarser product size of 15.5 pm. In addition, test results indicate that optimizing media sizes, solids concentration, and using viscosity modifiers enhance coal ultra-fine grinding performance. Under the optimized testing conditions, a P-80 of 2.7 pm was produced with a corresponding SE input of 270 kWh/ton using silica beads ranging from 420 to 850 pm and a dispersant dosage of 14 kg/ton. Moreover, the mathematical models generated based on population balance modeling provided an accurate forecast of the particle-size distribution. (C) 2022 Elsevier B.V. All rights reserved.