Altair jig: an in-plant evaluation for fine coal cleaning

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Coal preparation plants treat a majority of the run-of-mine coal using various gravity processes, which are known for their low cost and high process efficiency values. Due to the inefficiencies of conventional gravity-based processes in treating −1 mm coal, froth flotation processes are traditionally employed at a relatively high cost. To address cost and separation performance issues, several enhanced gravity separation technologies have been developed and evaluated which may allow effective gravity-based separation to particle sizes as small as 25 μm. The Altair centrifugal jig is an enhanced gravity technology, whose suitability for fine coal cleaning has been demonstrated through an in-plant study as reported in this publication. A relatively low specific gravity cut-point of 1.50 with a probable error value of 0.11 over a wide particle size range 1 mm×45 μm is indicative of the excellent separation performance achievable from the Altair jig. Tests performed with and without ragging material were performed with the goal that the latter would provide enhanced throughput capacities. However, although the performance was close to the theoretical limits over the broad range of product grades generated, the no-ragging experiments resulted in a significant loss in coal recovery under the given conditions. Overall, the centrifugal jig achieved 80% ash rejection and 50% total sulfur rejection while recovering nearly 80% of the combustibles.