Performance Testing of Ultrafine Pittsburgh #8 Coal in 12-Inch Advanced Flotation Column

The criteria for selecting a suitable advanced physical coal cleaning technology are: (1) maximum removal of pyritic sulfur with optimum Btu recovery, (2) high probability of commercial application, and (3) more cost-effective than flue gas desulfurization technology on a $/ton of sulfur removed basis. One physical cleaning technology having the potential to meet these criteria is advanced froth flotation. Babcock & Wilcox (B&W) has participated with ICF Kaiser Engineers to perform a OOE-supported project entitled "Engineering Development of Advanced Physical Fine Coal Cleaning Technologies - Froth Flotation." B&W was responsible for performing process studies in two areas. The rust area was precleaning of the raw Pittsburgh #8 coal in conventional coal preparation equipment (hydrocyclones and rougher flotation cells) to prepare the coal for ultrafine grinding and advanced froth flotation(1). The second area, which is the subject of this paper, was the ultrafine grinding and advanced froth flotation testing. Bench-scale and pilot-scale (100 to 200 pounds/hour) tests were conducted at B&W's Alliance Research Center. An 8-liter pilot wet stirred ball mill was used to determine the operating conditions (rpm, media volume, feed solids concentration, and feed rate) and specific energy required to produce the ultrafine coal feed for advanced flotation. Two-inch diameter and 12-inch diameter flotation column cells were used to develop engineering performance and scale-up data for the advanced flotation process. The operating conditions and performance results of the ultrafine grinding and the advanced froth flotation testing are discussed.