Ash removal from the Afsin/Elbistan lignite and the effects on power station operation

Results and discussions of the experimental works carried out to reduce the ash content and improve the ash characteristics of the lignite received by the coal-fired boiler in Afsin/Elbistan power plant are presented. Ash-making mineral matter crushed to -1.397 to +0.246 mm was reduced from 39.4 to 27.1% (dry basis) by means of a shaking-table operation. Tailings obtained from the tabling were admixed to the -0.246 mm fraction and further ground to -0.074 mm to improve liberation of the coal particles from the finely disseminated ash. The ash content of this fraction was removed by the fuel oil agglo-flotation method. The concentrates obtained by tabling and flotation were blended. A final clean product containing 29.8% ash with 4152 kcal kg(-1) net calorific value was obtained with 79.0% total cleaning recovery from the sample by this method. The effects of reduction in ash content and improvements in ash characteristics on the base/acid ratio, melting point and calorific values of the products were studied, and possible technical and economic aspects of the cleaning were discussed.