IMPROVING LABORATORY FLOAT/SINK METHODS FOR FINE-COAL LIBERATION

BECAUSE OF MORE STRINGENT SULFUR DIOXIDE EMISSION RESTRICTIONS BEING IMPOSED UNDER THE CLEAN AIR ACT, MANY DOMESTIC UTILITIES PRESENTLY BURNING HIGHER SULFUR CONTENT COALS ARE FORCED TO SWITCH TO LESS FAVORABLE LOWER SULFUR CONTENT WESTERN COALS OR TO ADOTP EXPENSIVE OFF-GAS TREATMENT SYSTEMS. THIS SITUATION MAY SIGNIFCANTLY INCREASEUTILITY RATES AND DESTABILIZE THE HIGHER SULFUR COAL INDUSTRY, WHICH IS VITAL TO MANY STATE ECONOMIES. HOWEVER, RECENT STUDIES BY THE ELECTRIC POWER RESEARCH INSTITUTE INDICATE THAT MANY HIGHER SULFUR COAL RESERVES MAY REMAIN ACCEPTABLE FEEDSTOCKS IF MORE EFFICIENT COAL CLEANING AND OFF-GAS TREAMENT TECHNOLOGIES ARE COMMERCIALIZED. BECAUSE OF THIS NEED AND GOVERNMENT FINANCIAL INCENTIVES, MANY PROCESS ENGINEERING FIRMS ARE DEVELOPING AND TESTING ADVANCED PHYSICAL COAL CLEANING PROCESSES. THESE TECHNOLOGIES ALL INVOLVE FINE, TO EXTREMELY FINE, COAL GRINDING TO LIBERATE MINERAL PARTICLES, PARTICULARLY PYRITES, FROM THE COAL. EVALUATION OF THESE TECHNOLOGIES REQUIRES THAT PROCESS PERFORMANCE RESULTS BE COMPARED TO LABORATORY PROCEDURES THAT DEFINE THE EASE OF LIBERATION OF MINERAL PARTICLES FROM THE COAL. UNFORTUNATELY, THE STANDARD METHOD OF DEFINING LIBERATION, CENTRIFUGAL FLOAT/SINK SEPARATION IN ORGANIC LIQUIDS, IS NO LONGER ACCURATE AT THESE FINE SIZES (BELOW 20 MICRON MEAN PARTICLE SIZE). PHASE I OF THIS PROJECT INCLUDES A TEST PROGRAM DESIGNED TO INVESTIGATE ALTERNATIVE MEDIA OPTIONS FOR FINE-COAL CENTRIFUGAL FLOAT/SINK ANALYSIS TO IMPROVE THE PERFORMANCE OF EXISTING METHODS.