Coal breaker

A coal breaker is a coal processing plant which breaks coal into various useful sizes. Coal breakers also remove impurities from the coal (typically slate) and deposit them into a culm dump. The coal breaker is a forerunner of the modern coal preparation plant.

Generally speaking, a coal tipple was typically used at a bituminous coal mine, where removing impurities was important but sorting by size was only a secondary, minor concern. Coal breakers were always used (with or without a tipple) at anthracite mines. While tipples were used around the world, coal breakers were used primarily in the United States in the state of Pennsylvania (where, between 1800 and the mid-20th century, many of the world's known anthracite reserves were located). At least one source claims that, in 1873, coal breaking plants were found only at anthracite mines in Pennsylvania.

The first function of a coal breaker is to break coal into pieces and sort these pieces into categories of nearly uniform size, a process known as breaking. The second function of a coal breaker is to remove impurities (such as slate or rock), and then grade the coal on the basis of the percent of impurities remaining. The sorting by size is particularly important for anthracite coal. In order to burn efficiently, air must flow evenly around anthracite. Subsequently, most anthracite coal is sold in uniform sizes. In the 1910s, there were six commercial sizes of coal (with the smallest size having three subsets):

Coal pieces smaller than 0.09375 inches in size were considered "culm," and unable to be separated from the impurities (and thus useless). The grade of coal ranged from a low of 5 percent impurities for steam or broken coal to a high of 15 percent for pea-size coal and its subsets.

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).

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