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Performance Optimization of a New Air Table and Flip-flow Screen for Fine Particle Dry Separation

ABSTRACT The mining industry has seen increased efforts toward achieving dry mineral separation owing to current and projected water scarcity and environmental problems associated with conventional wet processing methods. Commercially available dry coal separation technologies such as air tables and air jigs have proven effective in cleaning only the +6.35 mm while the −6.35 mm comprised of coal and impurities is discarded or used without further cleaning. To address this issue, a new density-based dry separator named SIU Airtable was developed. The main objective of this study was to evaluate the fine coal (6.35 × 1 mm) dry cleaning performance of the developed air table. The study also sought to evaluate the dry screening performance of the Liwell flip-flow screen to achieve efficient size separations at 1 and 2 mm. Two different Illinois No. 6 coal samples were used to optimize the new air table by varying its operating variables. The analysis of separation efficiency showed similar trends for both coal samples based on the cut point density (SG50) and probable error (Ep). Additionally, separation efficiency was significantly higher for the 6.35 × 3.36 mm size fraction and reduced when the size range was broadened to 6.35 × 1 mm. Product coal ash of 13.8–14.5% and tailings ash of 52.9–59.7% were achieved from the feed ash of 31–36%. Screening experiments on the Liwell flip-flow screen showed an efficiency of 88.7% and 85.1% achieved for the 1-mm and 2-mm polyurethane panels, respectively.