An extensive collection of document files on cokemaking provides information on the following coke and coke-related subjects: U.S. coke overview (1949-91), U.S. coke industry history and historical coke-oven data, U.S. coke facility analyses, U.S. beehive and byproduct coke (1909-62), U.S. coke capacity in selected years (1960-99), U.S. captive and merchant coke plants, U.S. coke-oven shutdowns (1980-85), U.S. coke production (1906-99), U.S. coke-market trends and outlook, U.S. coke import statistics, U.S. coke-supply deficit, U.S. coke-quality analysis, North American cokemaking, western world coke capacity and production (1983-92), world coke market, world production and capacity, world coke plants in 1992, cokemaking in selected countries and regions (Canada, China, Europe, and Japan), formcoke technology, Ancit formed coke process, DKS formed coke process, FMC coke production vs. byproduct ovens, Inland Steel formcoke project, history of nonrecovery cokemaking, Jewell-Thompson nonrecovery ovens at Sun Coke, Inland Steel nonrecovery coke project, Thyssen Still Otto PACTI coke ovens, and nonrecovery foundry coke.
The files also contain information on: coke-oven environmental requirements, Clean Air Act Amendments of 1990, Clean Air Act Revised Track Selections, pollution control in Germany vs. other countries, pushing-emmission control, Koppers side-emmission control, changes in cokemaking in 1896, cost per ton of coke in 1892, continuous coking, metallurgical coal fluidity, coal selection, use of non-coking coals, coke quality and blast-furnace performance, international coke rates, coke-rate reduction, tall coke ovens, foundry coke, coke byproducts (1912-22), coke and the tar industry, dry coke quenching, life of coke ovens, coke-oven repair, coke costs, briquette-blend coking, Clairton coke qualities, Connellsville coke, Elk River Resources profile, Fairmont Energy coke plant, H.C. Frick Coke Company, Jewell Coal and Coke Company profile, Keystone Coke Company, Klockner-RAG coke agreement, LTV/Pittsburgh coke plant closing, Mitsubishi coke, New Boston Coke Corporation, and Pennsylvania Coke Technology, Inc.
The files contain papers and publications on coke and cokemaking from many sources, including AISI, IISI, Fordham’s IERI, Carl Still, Gerd Nashan, and Eugene T. Sheridan of the U.S. Bureau of Mines. Other information on coke is contained in the Archive’s following books and references: Carnegie-Illinois Steel Corporation’s Coke and Coal Chemical Plants; Koppers Company’s Directory of By-Product Coke Plants of the Western Hemisphere and Koppers-Becker Coke Ovens, 1893-1943; Report to the AISI Committee on Technology, Alternative Cokemaking Technologies; and Analysis of the U.S. Metallurgical Coke Industry, a U.S. Department of Commerce study by Father Hogan and Frank T. Koelble.
Analysis: Coke is produced by heating selected metallurgical coals in coke ovens at high temperatures to drive off volatile hydrocarbons and obtain a hard, porous material, high in fixed carbon (about 90%) and preferably low in ash and sulfur. These properties are required to efficiently operate blast furnaces at integrated steel plants and cupola furnaces at foundries that manufacture iron castings
Considering that coke is an essential input for blast-furnace operations and that the blast furnace will continue to support a substantial, if not a major portion of world steel output for at least the next two decades, assured and economic supplies of coke will continue to be of critical importance to the steel industry’s integrated companies. However, as the 2003-04 run-up in world coke prices demonstrated, the availability and cost of their coke will continue to be impacted by increasingly restrictive environmental and public-health standards and related additional losses from an aging base of world coke-oven capacity.
Faced with this outlook, integrated steel companies will have to decide whether to: 1) continue closing coke plants and become increasingly dependent on outside coke purchases, which may or may not be reliable; 2) initiate or increase pulverized coal injection (PCI) or the use of natural gas and other supplemental fuels to displace a greater portion of their current coke needs; 3) make large capital investments, either independently or on a joint-venture basis, to rebuild or replace existing coke-oven batteries; 4) make equal or larger investments in new blast-furnace alternatives that smelt iron with coal instead of coke; 5) abandon all or a portion of their integrated iron and steel operations in favor of electric-furnace steel production; or 6) cede an increasing share of the steel market, particularly its flat-rolled segment, to their minimill competitors.
The beehive process, the world’s dominant cokemaking method at the start of the last century, is now moving closer to extinction, particularly since China has decided to shut down its so-called “antique” beehive ovens. All but a small portion of the world’s coke is now produced in byproduct ovens, which unlike the beehives, recover the volatiles evolved in the carbonization process. Introduced shortly before 1900, the first byproduct ovens were some 20 times more costly to build. Over time, however, it became widely recognized that they produced higher quality metallurgical coke, afforded higher yields of coke from coal, and required less coking time and manual labor. They also provided for the recovery of usable gas and salable byproducts, including benzene, sulfur, ammonia, naphtha, tar, and pitch. By the 1920’s, these many advantages had seen the byproduct process become the world’s leading way to make coke.
Beehive ovens are refractory-lined kilns, domed or beehive-like in structure, and often built into the side of a hill or embankment in the vicinity of a coalmine. Typically just under 4m in diameter at the base and nearly 3m high, the ovens are usually linked to form batteries, each oven being charged from the top with up to 13.5 tons of coal. Heat from the previous charge initiates the coking process, during which the coal is heated and carbonized in the presence of a controlled amount of air, with the resulting gases and volatiles being vented through the charging hole. Coking times commonly range from 48 to 72 hours.
Byproduct cokemaking is a distillation process using slot-shaped, retort ovens, which in a number of recently installed coke plants are 6m high, 15m long, and some 45cm wide. The process is most often installed within steel plants and incorporates a battery of ovens and a heating and regenerating system. Coal is charged through the top of each oven and is heated and carbonized during 13-18 hours in the absence of air at temperatures averaging 1200 deg. C (foundry coke requires up to a 30-hour coking time at about 980 deg. C). The red-hot coke is pushed out of one end of the oven (the coke side) by means of a mechanical ram acting from the other end (the pusher side). As the coal is being coked, refractory lined doors completely seal the ends of each oven, and the volatiles pass through top openings to a cooling apparatus for byproduct recovery.
Nonrecovery coke-oven technology has emerged as a viable alternative to the byproduct approach for producing coke in an environmentally compatible way. The U.S. Environmental Protection Agency (EPA) has designated the nonrecovery coke ovens of Sun Coal and Coke Company as representing the maximum achievable control technology (MACT) under the Clean Air Act. Operating the ovens under negative pressure attains compliance with a zero-door-leak standard, and because the volatiles from carbonization are completely combusted and not recovered as byproducts, potential environmental problems related to byproduct recovery are likewise avoided. A portion of the energy from combustion is used in closed-loop fashion to sustain the coking process, and the balance is capable of being used to co-generate salable steam and electricity.
Nonrecovery technologies with the most commercial operating experience include Sun Coal’s and another developed by Pennsylvania Coke Technology and licensed to Thyssen Still Otto, the German coke-plant builder. Sun Coal uses Jewell-Thompson heat-recovery ovens, which have undergone 40 years of operational development and commercial use at Jewell Coal and Coke Company in Vansant , Virginia . Since 1998, 248 of the ovens have been in commercial use at Ispat Inland, Inc., producing more than one million annual tons of blast-furnace coke and some 90MW of electricity from a co-generation plant built and operated by Primary Energy. The Thyssen Still Otto/PACTI process has been tested since 1997 at a full-scale, two-oven plant in Nueva Rosita , Mexico , and 142 similar ovens are operated commercially at New South Wales , Australia to produce some 225 thousand tons of coke annually.
Other nonrecovery-type coke ovens of proprietary design are located at Amona, Goa in India , where the Sesa Kembla Coke Co. Ltd. operates an 84-oven coke battery producing 280 thousand annual tons, and in China , where Shanxi Sanjia Coal-Chemistry Co. Ltd. of Jiexiu , Shanxi has developed another design, SJ-96.