China Many historical sources dating to the 4th century describe the production of coke in
ancient China. The Chinese first used coke for heating and cooking no later than the 9th century. By the first decades of the 11th century, Chinese ironworkers in the
Yellow River valley began to fuel their furnaces with coke, solving their fuel problem in that tree-sparse region. By 1078 CE, the implementation of coke as a replacement to charcoal in the production of iron in China dramatically increased the industry to 125,000 tons per year. The iron was used for the creation of tools, weapons, chains for suspension bridges, and Buddhist statues. China is the largest producer and exporter of coke today. China produces 60% of the world's coke. Concerns about
air pollution have motivated technological changes in the coke industry by elimination of outdated cooking technologies that are not energy-efficient.
Great Britain In 1589, a patent was granted to Thomas Proctor and William Peterson for making iron and
steel and melting lead with "earth-coal, sea-coal, turf, and peat". The patent contains a distinct allusion to the preparation of coal by "cooking". In 1590, a patent was granted to the
Dean of York to "purify pit-coal and free it from its offensive smell". In 1620, a patent was granted to a company composed of William St. John and other knights, mentioning the use of coke in smelting ores and manufacturing metals. In 1627, a patent was granted to Sir John Hacket and Octavius de Strada for a method of rendering sea-coal and pit-coal as useful as
charcoal for burning in houses, without offense by smell of smoke. In 1603,
Hugh Plat suggested that coal might be charred in a manner analogous to the way
charcoal is produced from wood. This process was not employed until 1642, when coke was used for roasting
malt in
Derbyshire; previously, brewers had used wood, as uncoked coal cannot be used in brewing because its sulphurous fumes would impart a foul taste to the
beer. It was considered an improvement in quality, and brought about an "alteration which all England admired"—the coke process allowed for a lighter roast of the malt, leading to the creation of what by the end of the 17th century was called
pale ale. In 1768,
John Wilkinson built a more practical oven for converting coal into coke. Wilkinson improved the process by building the coal heaps around a low central chimney built of loose bricks and with openings for the combustion gases to enter, resulting in a higher yield of better coke. With greater skill in the firing, covering, and quenching of the heaps, yields were increased from about 33% to 65% by the middle of the 19th century. The Scottish iron industry expanded rapidly in the second quarter of the 19th century, through the adoption of the hot-blast process in its coalfields. In 1802, a battery of beehive ovens was set up near
Sheffield, to coke the
Silkstone coal seam for use in crucible steel melting. By 1870, there were 14,000 beehive ovens in operation on the
West Durham coalfields, producing 4,000,000 long tons of coke per year. As a measure of the expansion of coke making, the requirements of the
iron industry in Britain were about 1,000,000 tons per year in the early 1850s, rising to about 7,000,000 tons by 1880. Of these, about 5,000,000 tons were produced in Durham county, 1,000,000 tons in the South Wales coalfield, and 1,000,000 tons in Yorkshire and Derbyshire. This was not technically possible to achieve until the
firebox arch came into use, but burning coke, with its low smoke emissions, was considered to meet the requirement. This rule was quietly dropped, and cheaper coal became the normal fuel, as railways gained acceptance among the public. The smoke plume produced by a travelling locomotive seems now to be a mark of a steam railway, and so preserved for posterity. So-called "gas works" produced coke by heating coal in enclosed chambers. The flammable gas that was given off was stored in
gas holders, to be used domestically and industrially for cooking, heating, and lighting. The gas was commonly known as "
town gas" since underground networks of pipes ran through most towns. It was replaced by "
natural gas" (initially from the
North Sea oil and gas fields) in the decade after 1967. Other byproducts of coke production included tar and ammonia, while the coke was used instead of coal in cooking ranges and to provide heat in domestic premises before the advent of
central heating.
Continental Europe In 1785, the first coke-fired iron was cast in France in
Le Creusot.
John Baildon, on the invitation of
Friedrich von Reden, was responsible for the introduction of coke into iron-making in Prussia (in Gleiwitz (
Gliwice), 1796, and, on a large scale, in Königshütte (
Chorzów), 1802).
The United States of America In the US, the first use of coke in an iron furnace occurred around 1817 at Isaac Meason's Plumsock puddling furnace and rolling mill in
Fayette County,
Pennsylvania. In the late 19th century, the
coalfields of
western Pennsylvania provided a rich source of raw material for coking. In 1885, the Rochester and Pittsburgh Coal and Iron Company constructed the world's longest string of coke ovens in
Walston, Pennsylvania, with 475 ovens over a length of . Their output reached 22,000 tons per month. The
Minersville Coke Ovens in
Huntingdon County, Pennsylvania, were listed on the
National Register of Historic Places in 1991. Between 1870 and 1905, the number of beehive ovens in the US increased from approximately 200 to nearly 31,000, which produced nearly 18,000,000 tons of coke in the Pittsburgh area alone. One observer boasted that if loaded into a train, "the year's production would make up a train so long that the engine in front of it would go to San Francisco and come back to Connellsville before the caboose had gotten started out of the Connellsville yards!" The number of beehive ovens in Pittsburgh peaked in 1910 at almost 48,000. Although it made a top-quality fuel, coking poisoned the surrounding landscape. After 1900, the serious environmental damage of beehive coking attracted national notice, although the damage had plagued the district for decades. "The smoke and gas from some ovens destroy all vegetation around the small mining communities", noted W. J. Lauck of the U.S. Immigration Commission in 1911. Passing through the region on train,
University of Wisconsin president
Charles Van Hise saw "long rows of beehive ovens from which flame is bursting and dense clouds of smoke issuing, making the sky dark. By night, the scene is rendered indescribably vivid by these numerous burning pits. The beehive ovens make the entire region of coke manufacture one of dulled sky: cheerless and unhealthful." File:Coke-Ovens---Cokedale-CO.jpg|Coal coking ovens at
Cokedale, Colorado, supplied steel mills in Pueblo, CO File:Cherry Valley Coke Ovens 3.jpg|The 200
Cherry Valley Coke Ovens built around 1866 File:Dunlap-coke-ovens-tn2.jpg|
Dunlap coke ovens File:Minersville Coke Ovens.jpg|
Minersville Coke Ovens File:Old coke ovens, Redstone, CO.jpg|
Redstone Coke Oven Historic District File:SydneyCokeOvenGeneralViewCa1900.jpg|
Sydney Tar Ponds ==See also==