Study on separation of low-rank coal macerals in enhanced gravity field

In this paper, the enhanced gravity separation of maceral components was studied based on the characteristics of maceral components for low-rank coal from Shendong. Vitrinite and ash content were only 48.42 and 8.77%, respectively. Rod mill grinding showed that the optimal grinding time was 10 min based on the vitrinite content and vitrinite recovery which reached maximum 81.34 and 80.85%, respectively. Maceral separation test conducted with the Falcon concentrator showed that using optimal conditions of rotary frequency 30 Hz, feed dosage 15 ml/s and recoil water pressure 0.03 Mpa, the best vitrinite content, benefication ratio and vitrinite recovery were 67.25%, 1.16, and 72.48%, respectively. With the increase of rotary frequency or decrease of recoil water pressure, the finer particles in each particle fraction became more underflow products, and these finer particles in underflow products were all high-density products with density higher than 1.35 g/cm(3). Because the content of vitrinite was higher in the coarser particles, the average particle size of the original overflow product was directly reduced by these fine particles entering the overflow product, which caused the decrease of vitrinite content and the increase of vitrinite recovery.