The objective of this study was to evaluate various multi-stage circuit
arrangements that may be used to improve the column flotation of micronized coal.
Laboratory flotation tests were perfonned with two different samples of Pittsburgh No.
8 seam coal. The first coal, Coal A, was ground to two different particle sizes and
subjected to both column and conventional flotation. These tests were perfonned to
obtain an initial understanding of the operational behavior of the column process and to
compare the results with those of conventional flotation. The second coal, Coal B, was
used in the actual testing of three different column circuit arrangements. The
experimental test results were compared to simulated results obtained using a rate-based
flotation model constructed in the present work. Several hypothetical flotation circuits
were also examined using the simulation model and experimental flotation rate data.
The circuit test results showed that each of the different circuit configurations
possessed specific advantages in terms of throughput capacity, combustible recovery, ash
rejection and sulfur rejection. However, the overall perfomlance curves for each circuit
were all found to fall on or just below the maximum separation curve predicted using the
release analysis technique. Also, the simulated results in almost all cases predicted better
results than what was actually obtained. This discrepancy was attributed to the inability
of the rate-based model to adequately describe restrictions associated with the carrying
capacity of the column froth.
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