Coal Breaker - Pre-breaker Treatment of Coal

Pre-breaker Treatment of Coal

Coal breakers were generally located as close to the anthracite mine entrance as possible, so as to minimize the distance the coal had to travel before processing. Prior to entering the breaker, the coal would be crushed and sorted in a coal tipple and, if necessary and if water was available, washed. All coal was screened in the tipple as it came out of the mine so that steam-sized or smaller pieces could travel immediately to the coal washer and/or coal breaker. Chunks of coal which were too large were then crushed (sometimes several times) in the tipple until it passed through the screen (e.g., was of acceptable steam size or smaller).

Coal is often mixed with impurities such as slate, sulphur, ash (or "bone"), clay, or soil, which requires that it be cleaned before shipment to market. Mine workers sampled the coal as it came out of the mine to determine whether the level of impurity recommended washing (if washing was available). Slate, sulphur, and ash have a higher relative density than coal, and will sink in agitated water. Passing the coal through the tipple was an essential pre-treatment process for coal washing, however, because the impure coal must be of similar sized lumps for coal washing to work. If coal washing was conducted, coal might enter the breaker "wet." This meant the incline of the various belts and conveyors must be lowered so that the coal did not slide on the belts or move too quickly down chutes. Where coal washing was used, the coal breaker was expanded to handle both "dry" and "wet" coal simultaneously.