It is recognized that the use of centrifugal gravity concentrators is more effective than conventional concentrators in recovering fine-grained coal tailing. In the Knelson concentrator study, fuzzy logic was used to investigate the prediction of ash content and combustible recovery. The Western Lignite Company (WLC) tailing sample was classified into -1+0.038, -1+0.212 and 0.212+0.038 mm size groups. In the prediction studies, centrifugal force (20, 30, 40 and 50 G) and flow rate (2, 3 and 4 L/min) were used as input variables. Then the results of the fuzzy logic prediction were compared with the actual values and found that the fuzzy logic system could be successfully applied to the Knelson concentrator enrichment results.