SBIR-STTR Award

A recently completed test program has demonstrated effectiveness and the potential of air-sparged hydrocyclone (ASH)flotation technology for fine coal cleaning. This test programconfirmed the ASH effectiveness with the separation efficienciesequivalent to those achieved by advanced conventional flotation,but at a specific capacity more than 300 times higher thanconventional or column flotation. However, the test program alsoshows that pyrite @on during both advanced conventional flotationand ASH flotation is still a problenl A proprietary froth washingsystem for improved rejection of the ash and pyritic sulfurcontaminants in the clean coal product is a recent development inASH design. The froth washer is located on the ASH unit's axis insuch a way that the froth product formed in the center of the ASHmust pass through a water spray, before the froth enters the vortexfinder and is discharged as an overflow product. Fine mineralparticles including pyrite particles inadvertently trapped in theforth phase thus will be reflected before they enter into thevortex finder and before they are discharged with the clean coalproduct. A significant improvement in the quality of the cleancoal product is thus expected. It is anticipated that furtherimprovement and utilization of this advanced ASH design will reducethe ash and pyrite content in the clean coal product. In Phase Ia system will be designed and built to evaluate and advance the newgeneration ASH system for fine coal flotation.Anticipated Results/Potential Commercial Applications as described by the awardee:The ASH technology for fine coal cleaning holds great promise, and further development is warranted for industrialapplication in fine coal cleaning. Successful completion of thisPhase I program will reduce the ash and pyrite content in the cleancoal product and lead to Phase II evaluation at a plant site withlarge ASH units. Commercial application of the ASH technology forfine coal flotation is thus expected.

A previously completed test program demonstrated the potential of air-sparged hydrocyclone (ASH) flotation technology for fine coal cleaning. This test program confirmed the ASH effectiveness with separation efficiencies equivalent to those achieved by advanced conventional flotation, at a specific capacity more than 300 times higher than conventional or column flotation. However, the test program also revealed that pyrite rejection during both advanced conventional flotation and ASH flotation still remains a challenge. Furthermore, the ASH flotation technology was demonstrated with only a small 2-inch diameter prototype unit. Scale-up questions still remain. Recently a further development in ASH design was achieved,incorporating a froth washing system located on the axis of the ASH unit. With this froth washing system, fine particles, particularly pyrite particles which are inadvertently trapped in the froth phase during flotation, can be rejected by the wash water before they enter into the vortex finder and can be discharged with the clean coal froth product. Significant improvement in clean coal quality thus can be achieved. This new design was patented and has been demonstrated to be effective during Phase I. Phase II will continue the advanced design of the air-sparged hydrocyclone system for fine coal flotation. Phase II will mainly involve in-plant, large scale testing.Anticipated Results Potential Commercial Applications as described by the awardee:Phase II of this project will provide technical confidence for the commercial utilization of ASH technology for fine coal cleaning and will provide scale-up infomlation for large diameter ASH units. Subsequent commercial application of the ASH technology for fine coal flotation is expected if the Phase II technical objectives are successfully realized. Economically, utilization of ASH technology will allow coal preparation plants to operate more cost_effectively. Environmentally, utilization of the ASH technology improves ash and pyrite rejection to reduce the nation's acid rain problem. Finally, utilization of ASH technology provides for energy conservation by providing for the recovery of fine coal frequently wasted as a reject from many preparation plants.