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Coal dust is a fine powdered form of coal, which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal.

Method of and Apparatus for Mixing Coal Dust and Air for Combustion

Coal dust is a fine powdered form of coal, which is created by the crushing, grinding, or pulverizing…

"A small skip; the upper illustration showing position for dumping. The lower cut is of a skip for either ore or water; note valve in bottom. Hoisting buckets or kibbles are employed for small scale work or temporary service, such as raising the material blasted in sinking shafts."—Encyclopaedia Britannica, 1910

Ore and Water Skips for Inclined Shaft

"A small skip; the upper illustration showing position for dumping. The lower cut is of a skip for either…