DEVELOPMENT OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY (CCSEM) TECHNIQUES FOR PREDICTING THE CLEANING BEHAVIOR OF COAL

NEW RESTRICTIONS PROPOSED FOR SULFUR AND PARTICULATE EMISSIONS FROM COAL-BURNING UTILITY PLANTS HAVE STIMULATED RENEWED INTEREST IN A VARIETY OF ADVANCED COAL CLEANING TECHNIQUES. THESE TECHNIQUES INCLUDE A VARIETY OF PHYSICAL CLEANING METHODS SUCH AS FROTH FLOTATION, COLUMN FLOTATION, AND SELECTIVE OIL AGGLOMERATION. THESE CLEANING METHODS, WHICH ARE APPLIED TO HIGHLY COMMINUTED COAL, ARE HIGHLY SENSITIVE TO TWO PRIMARY FACTORS: THE DEGREE OF LIBERATION OF MINERAL MATTER FROM COAL AND THE SURFACE STATE OF BOTH THE COAL AND MINERAL PARTICLES. THIS PROPOSAL OUTLINES A PROGRAM TO DETERMINE THE FEASIBILITY OF USING COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY (CCSEM), WITH COMPLEMENTARY SURFACE STATE MEASUREMENTS BY MOSSBAUER SPECTROSCOPY AND X-RAY PHOTOELECTRON SPECTROSCOPY (XPS), AS A DIAGNOSTIC TECHNIQUE FOR PREDICTING COAL RESPONSE TO SUCH ADVANCED CLEANING PROCESSES. THE CCSEM MEASUREMENTS WILL UTILIZE NEWLY DEVELOPED MICROIMAGING TECHNOLOGY TO ASSIST IN THE INTERPRETATION OF ENERGY DISPERSIVE SPECTROSCOPY (EDS) DATA TO DETERMINE DENSITY ON A PARTICLE-BY-PARTICLE BASIS, AND A DIGITAL IMAGING PROCESSING TO DETERMINE THE AMOUNT OF MINERAL SURFACE EXPOSED BY COMMINUTION.