Supergravity separation: An innovative strategy for efficient cleaning and upgrading of coal gasification slag waste

Conventional carbon recovery methods from coal gasification residues are plagued by inefficiency, high costs, and suboptimal environmental performance, necessitating the development of a novel approach that is both efficient and environmentally sustainable. Enrichment of residual carbon in coal gasification coarse slag was investigated using supergravity separation. The impact of operational parameters, specifically rotational speed and jet water pressure, on separation performance was evaluated using a novel multi-stage supergravity concentrator. The study delved into the synergistic mechanisms of centrifugal stratification and hydrodynamic erosion, analysing the microscopic properties of the separated products. Optimal separation conditions for various particle size fractions were identified, leading to high combustible recoveries. The kinetic erosion effect of the backwash jet was found to significantly enhance the separation process by effectively removing inorganic particles adhering to the residual carbon surface. Microscopic analysis confirmed that the surface of the separated concentrate exhibited improved cleanliness and smoothness relative to the original samples, indicating successful removal of inorganic impurities. Sequential separation by centrifugal force coordinated with backwash jets effectively solved the challenges posed by heterogeneous distribution and surface attachment during beneficiation, realizing efficient recovery of residual carbon in coal gasification coarse slag. Under optimal conditions, combustible recoveries of 93.89 %, 93.22 %, and 94.32 % were achieved for the 0.5 - 1 mm, 0.25 - 0.5 mm, and - 0.25 mm fractions, respectively. The study demonstrates the effectiveness of supergravity separation for residual carbon enrichment in coal gasification slag, offering an innovative solution for the improved application of supergravity separation and the recovery of coal-based solid waste resources.