The effect of premixing on the floatation of oxidized Amasra coal

in this study factors affecting the floatation efficiency of oxidized Amasra coal containing high quantities of inorganic materials were examined under laboratory conditions. The Amasra coal samples were oxidized by exposing them to atmospheres for a long time with the aim of obtaining coal having a lower ash content. Premixing is applied to condensed pulp containing 60% coal and 40% water to remove the oxidized layer on the coal surface. The oxidized layer is removed as a result of friction between particles during mixing. Premixing periods were 1, 2, 3, 4, 5, 10, 15 and 20 min, and floatation tests were done after each premixing. Some relations were obtained between frothing period, calorific value, combustible matter recovery, and ash content. The relation between premixing and floatation efficiency was another subject of examination. The effect of oxidized coal on floatation was also examined after oxidized coal was exposed to thermal treatment in inert milieu. From the results obtained at the end of an average frothing period of 20-25 min, it was observed that the quantity of product increased and the ash content in the product reached a minimum value. At the same time, the calorific value of the coal and the recovery of combustible matter reached their highest value. (C) 1997 Elsevier Science B.V.