WET COUNTERCURRENT OPEN GRADIENT MAGNETIC SEPARATION OF PYRITE FROM COAL

THIS RESEARCH PROGRAM WILL DEMONSTRATE THE TECHNICAL AND ECONOMIC FEASIBILITY OF THE PROPOSED MAGNETIC SEPARATOR ON PULVERIZED COAL. A THEORETICAL COMPARISON OF THE PROPOSED SEPARATOR WITH WORK PUBLISHED ON OPEN GRADIENT MAGNETIC SEPARATION BY THE OAK RIDGE NATIONAL LABORATORY INDICATES THAT THE SEPARATOR WILL HAVE HIGH LEVELS OF ASH CLEANING. THIS IS BECAUSE OF ITS COUNTERCURRENT PRINCIPLE OF OPERATION, THE HIGH GRADIENT MAGNETIC FIELD OCCURRING IN THE NARROW GAP THROUGH WHICH THE COAL IS TRANSPORTED AND THE LIMITED MOVEMENT NECESSARY TO EFFECT SEPARATION. LOW PROCESSING COST AND HIGH LEVELS OF PYRITIC SULFUR REMOVAL ARE EXPECTED. THE SEPARATOR CAN BE LINEARLY AND ECONOMICALLY SCALED TO MANY TONS PER HOUR. THE SEPARATOR HAS BEEN TESTED ON DRY 10 MICRON DIAMETER COALAND MEASURABLE SEPARATION OF BOTH ASH AND SULFUR WAS OBTAINED. VERY STRONG ELECTROSTATIC EFFECTS WERE ALSO OBSERVED, THAT IN SOME CASES WERE SUFFICIENT TO REVERSE THE SEPARATION. THEORETICAL ANALYSIS OF THE DRY MAGNETIC SEPARATION INCLUDING THE ELECTROSTATIC EFFECTS EXPLAINS BOTH THE SIGN AND MAGNITUDE OF THE OBSERVED SEPARATIONS. THIS SAME ANALYSIS SHOWS THAT USING A CONDUCTIVE FLUID WITH A RESISTIVITY LESS THAN 3 X 10(5) CM COMPLETELY ELIMINATE ALL ELECTROSTATIC EFFECTS. WATER WITH MORE THAN 2PARTS PER MILLION OF SODIUM CHLORIDE OR SIMILAR ELECTROLYTE IS SUFFICIENTLY CONDUCTIVE FOR ELECTROSTATIC EFFECTS TO BE NEGLIGIBLE.