ADVANCED DESIGN OF AIR-SPARGED HYDROCYCLONE SYSTEM FOR FINE COAL FLOTATION

THE RECENTLY COMPLETED TEST PROGRAM BY PENELEC AT THE EPRI/CQDC TEST FACILITY, HOMER CITY, PA, UNDER DOE CONTRACT DE-AC22-88PC88853 HAS AGAIN DEMONSTRATED THE EFFECTIVENESS AND THE POTENTIAL OF ASH FLOTATION TECHNOLOGY FOR FINE COAL CLEANING. THIS TEST PROGRAM CONFIRMED THE ASH EFFECTIVENESS WITH THE SEPARATION EFFICIENCIES EQUIVALENT TOTHOSE ACHIEVED BY ADVANCED CONVENTIONAL FLOTATION, BUT AT A SPECIFIC CAPACITY MORE THAN 300 TIMES HIGHER THAN CONVENTIONAL OR COLUMN FLOTATION. HOWEVER, THE TEST PROGRAMALSO REVEALS THAT PYRITE REJECTION DURING BOTH ADVANCED CONVENTIONAL FLOTATION AND ASH FLOTATION STILL REMAINS A CHALLENGE. RECENTLY, ADVANCED PROCESSING TECHNOLOGIES, INC. HAS ANNOUNCED A FURTHER DEVELOPMENT IN ASH DESIGN WITH PROPRIETARY FROTH WASHING SYSTEM FOR IMPROVED REJECTION OF THE ASH AND PYRITIC SULFUR CONTAMINANTS IN THE CLEAN COAL PRODUCT. THE FROTH WASHER IS LOCATED ON THE AXIS OF THE ASHUNIT IN SUCH A WAY THAT THE FROTH PRODUCT FORMED IN THE CENTER OF THE ASH HAS TO PASS THROUGH A WATER SPRAY BEFORE THE FROTH ENTERS THE VORTEX FINDER AND IS DISCHARGED AS AN OVERFLOW PRODUCT. FINE MINERAL PARTICLES INCLUDING PYRITE PARTICLES INADVERTENTLY TRAPPED IN THE FROTH PHASE THUS SHOULD BE REJECTED BEFORE THEY ENTER INTO THE VORTEX FINDER AND BEFORE THEY ARE DISCHARGED WITH THE CLEAN COAL PRODUCT. A SIGNIFICANT IMPROVEMENT IN THE QUALITY OF THE CLEAN COAL PRODUCT IS THUS EXPECTED. IT IS ANTICIPATED THAT THE FURTHER IMPROVEMENT AND UTILIZATION OF THIS ADVANCED ASH DESIGN WILL REDUCE THE ASH AND PYRITE CONTENT IN THE CLEAN COAL PRODUCT BEING LIMITED ONLY BY THE EXTENT OF LIBERATION. IN VIEW OF THIS NEW DEVELOPMENT A TEST PROGRAM IS PROPOSED TO DOE TO EVALUATE AND ADVANCE THE NEW GENERATION ASH SYSTEM FOR FINE COAL FLOTATION.