Effectiveness of the dense medium and the froth flotation methods in cleaning some Turkish lignites

The feasibility of cleaning three Turkish lignites (Beypazari, Golbasi and Kangal lignites) by the dense medium separation or the froth flotation method has been investigated. Solutions of zinc chloride (ZnCl2) with specific gravities ranging from 1.1 to 1.75 have been used as the dense medium. In the case of froth flotation, methyl isobutyl carbinol (MIBC), diethyl isohexanol (DEH) and sodium dodesyl sulphonate (SIDS) were used as the frother and kerosene was used as the collector. In both methods, each lignite sample was separated into two sub-fractions: the lignite rich part and the mineral matter rich part. The results indicate that the effectiveness of the methods in ash and sulphur removal is appreciably different for the different lignites. An effective pyritic sulphur removal (over 90%) was obtained for Beypazari or Golbasi lignites by the dense medium separation. The effectiveness of the froth flotation was relatively different depending on both the lignite and frother type. The recovery is generally low and changes considerably depending on the frother type and particle size. (C) 2003 Elsevier Ltd. All rights reserved.