KSEF R&D Excellence: Innovative Coal Beneficiation Process - Picobubble Enhanced Flotation for Efficient Recovery of Coarse and Ultrafine Particles with Less Reagent

The Commonwealth of Kentucky is the third largest coal producing state in the U.S. with an annual output of more than 160 million tons. More than 95% electricity is generated &om coal in Kentucky. Fine coal (smaller than 28 mesh or 0.6 mm), which amounts to 10-20% overall product, is often beneficiated using &oth flotation process which exploits the difference in surface characteristics between coal and minerals. However, its application is often limited to a very narrow particle size range, nonnallyl 0-100 Jlm. It is not effective for beneficiation of relatively coarse and ultrafine particles «3 Jlm). As a result, cleaning of coal in relatively coarse size &action (e.g., 8-28 mesh or 0.6-2.4 mm) is often accomplished using low efficiency gravity separators such as spirals; no effective process is available for recovery of micron or sub-micron uItrafine coal. The proposed research program is intended to develop an innovative flotation process for enhanced recovery of relatively coarse (0.6-2.4 mm) and fine particles (-0.6 mm), particularly ultrafine «3 Jlm) particles. Picobubble (usually smaller than 1 Jlm) technology incorporated into modified mechanical and column flotation cells will be investigated as a cost effective method to achieve the goal by increasing the particle-bubble collision probability and decreasing the detachment probability. Picobubbles are characterized by inherently high probability of collision with particles and high probability of attachment and low probability of detachment due to their tiny size, low ascending velocity and rebound velocity &om the surface, and high surface ⅇ energy to be satisfied. Our preliminary studies have shown that the proposed process is fundamentally sound and practically feasible. The potential benefits include considerably enhanced recovery, substantially reduced flotation reagents, significantly lowered cost, simplified flowsheet, etc. The successful development of the proposed process will increase the competitiveness of the Kentucky coal energy industry, make good use of fine coal as a significant energy source, and mitigate environmental pollution caused by fine coal slurry.