CENTRIFUGAL FLOAT-SINK SEPARATION OF FINE TURKISH COALS IN DENSE MEDIA

Zonguldak bituminous coal, Tuncbilek and Soma-Merkez lignites were eac h separated into two sub-fractions, coal rich and mineral matter rich, using a centrifugal float-sink separation technique in heavy media. A n isopropyl alcohol (IPA)-carbon tetrachloride (CCl4) mixture and a zi nc chloride (ZnCl2) solution, with a specific gravity of 1.40 g cm(-3) at 25 degrees C were used as dense medium liquids. The addition of su rface active agents (Triton X-100 and Brij-35) to the zinc chloride so lution improved the removal of minerals. The recovery and purity of th e final product (float) obtained from the heavy media separation depen d on such parameters as the density of the medium, rotor speed and cen trifugation time. The separation efficiency of each coal differed sign ificantly. Particle size distributions of the coals and their float an d sink fractions were analysed using a Laser Particle Size Analyser. A Scanning Electron Microscope (SEM) was used to interpret the liberati on of minerals from the coal particles. (C) 1998 Elsevier Science B,V. All rights reserved.