Editing Coke (fuel) (section)

===Beehive coke oven===
{{main|Beehive oven }}
[[File:Coke ovens and coal tipple, Fayette County, Penn (68762).jpg|thumb|Postcard depicting coke ovens and coal [[tipple]] in Pennsylvania]]

A fire brick chamber shaped like a dome is used, commonly known as a beehive oven. It is typically about {{convert|4|m|ft|0|sp=us}} wide and {{convert|2.5|m|ft|0|sp=us}} high. The roof has a hole for charging the coal or other kindling from the top. A discharging hole is provided in the circumference of the lower part of the wall. In a coke oven battery, a number of ovens are built in a row with common walls between neighboring ovens. A battery consisted of a great many ovens, sometimes hundreds, in a row.<ref>{{cite web|title=Manufacture of Coke at Salem No. 1 Mine Coke Works|url=http://patheoldminer.rootsweb.ancestry.com/coke2.html|publisher=Pathoftheoldminer|url-status=dead|archive-url=https://web.archive.org/web/20130703201913/http://patheoldminer.rootsweb.ancestry.com/coke2.html|archive-date=3 July 2013|access-date=14 May 2013}}</ref>

Coal is introduced from the top to produce an even layer of about {{convert|60 to 90|cm|in|0|sp=us}} deep. Air is supplied initially, to ignite the coal. [[Carbonization]] starts and produces volatile matter, which burns inside the partially closed side door. Carbonization proceeds from top to bottom and is completed in two to three days. The heat required for the process is supplied by the burning volatile matter, so no by-products are recovered. The exhaust gases are allowed to escape to the atmosphere. The hot coke is quenched with water, and is discharged manually through the side door. When the oven is used on a continuous basis, the walls and roof retain enough heat to initiate carbonization of the next charge.<ref>Gates, John K. (1990). ''The Beehive Coke Years: A Pictorial History of Those Times''. Uniontown, Pennsylvania: John K. Gates. 128 pp. Library of Congress Catalog Card Number 90-93278. ("If the oven had been pulled less than about four hours before it was charged, it was a 'hot' oven and the coal would catch fire ...", p. 119).</ref>

When coal was burned in a coke oven, the impurities of the coal that were not driven off as gases accumulated in the oven as slag – effectively a conglomeration of the removed impurities. Since this slag was not the desired product, it was initially just discarded. Later, however, coke oven slag was found to be useful, and has since been used as an ingredient in brick-making, mixed cement, granule-covered shingles, and even as a fertilizer.<ref>{{cite journal|title=Coke Ovens|journal=The Friends of the Cumberland Trail|url=http://friendsofthecumberlandtrail.org/history-and-culture/coke-ovens/|url-status=live|archive-url=https://web.archive.org/web/20120625023506/http://www.friendsofthecumberlandtrail.org/history-and-culture/coke-ovens/|archive-date=25 June 2012}}</ref>