Mining Contract: Development of an Anti-Caking Rock Dust
When exposed to moisture, limestone-based rock dusts have a tendency to cake and do not disperse easily when a light blast of air is applied. The focus of this contract is to develop anti-caking rock dusts.
Contract Status & Impact
This contract is ongoing.
The treatment of pulverized limestone has been conducted commercially since the 1980s. The measurement of the amount of anti-caking reagent on the treated products after manufacture has been a great asset in determining the performance of the treated products in end-use applications. This technology will be applied to the development of the anti-caking rock dust for use in the underground coal mines. Currently, no commercially available rock dusts meet the anti-caking specification of 30 CFR 75.2.
This contract has three phases: to evaluate two different commercially available treated ultrafine limestone products in relation to their particle size, chemical make-up, stearic acid treatment levels, and contact angles (Phase 1); from the results of this evaluation, make a series of blends where various untreated ground limestone products with different median particle sizes will be blended with the two products mentioned above (Phase 2); re-evaluate the samples from Phase 2 that have been found to meet the desired properties for anti-caking rock dust (Phase 3).
This contract is nearing the end of Phase 3, where samples from Phase 2 that have been found to best meet the desired properties for anti-caking rock dust are being re-evaluated. The three most promising blends, consisting of fresh mixtures of the treated and untreated limestone-based rock dust products, are undergoing a series of tests to determine their anti-caking characteristics. Explosibility testing is also being conducted within the OMSHR 20-L chamber to determine the inerting effectiveness of the blend when mixed with an explosible concentration of pulverized coal dust.
Following Phase 3, the most economically viable, successful blend will be selected for a pilot scale-up to confirm through testing that the blend can be accurately reproduced during large-scale production. If successful, sufficient quantities of the production blend will then be provided for large-scale evaluations within the OMSHR experimental mines followed by full-scale trials within an operating underground coal mine. Pending success from the full-scale trials and the Mine Safety and Health Administration’s acceptance of this treated rock dust product for use in underground coal mines, an anti-caking rock dust would then be commercially available that would meet all of the specifications of the 30 CFR 75.2 rock dust definition. Specifically and in the event of an explosion, the rock dust would be dispersible under all mining conditions, including areas that are wet, and thereby be capable of meeting its intended function of inerting coal dust.