Development of dry a beneficiation scheme for soma-imbat lignite by Allair Jig and Akaflow

Soma-Imbat lignite is a typical lignitic coal produced by Turkish Coal Enterprises. It is characterized by relatively moderate ash levels (37-40 %), low sulfur (0.54 %) and medium calorific values of 3062 Kcal/kg. Wet cleaning of this coal produces reasonably good quality clean coal with 15.5 % ash and combustible recoveries of 80.5 %. Problems with wet separation techniques such as the need for water shortage in arid areas and high cost of dewatering of coal fines make it necessary to introduce dry cleaning techniques. For this purpose, a pilot scale Allair Jig was used to determine the dry cleaning characteristics of Soma-Imbat lignite in size of -13 mm. Prior to application of dry beneficiation, some basic test were performed to determine the feed size or size fractions on separations to achieve maximum separation efficiencies. Beneficiation studies were conducted on size fractions of -13+4 mm and -4+1 mm using Allair Jig and on -1 mm using Akaflow aerodynamic separator. Different conditions of feed/discharge stargate, ventilator and flutter valve rates and vibration frequency (for Akaflow) were tested for optimization. The results reveal that dry separation for this particular coal is possible with relatively good coal recoveries. The results obtained with Allair Jig are discussed with the help of data on separation efficiencies.