coke

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coke,

substance obtained by the destructive distillationdistillation,
process used to separate the substances composing a mixture. It involves a change of state, as of liquid to gas, and subsequent condensation. The process was probably first used in the production of intoxicating beverages.
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 of bituminous coalcoal,
fuel substance of plant origin, largely or almost entirely composed of carbon with varying amounts of mineral matter. Types

There is a complete series of carbonaceous fuels, which differ from each other in the relative amounts of moisture, volatile matter,
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. Coke bears the same relation to coal as does charcoalcharcoal,
substance obtained by partial burning or carbonization (destructive distillation) of organic material. It is largely pure carbon. The entry of air during the carbonization process is controlled so that the organic material does not turn to ash, as in a conventional
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 to wood. A hard, gray, massive, porous fuel, coke is the solid residue remaining after bituminous coal is heated to a high temperature out of contact with air until substantially all components that easily vaporize have been driven off. The residue is chiefly carbon, with minor amounts of hydrogen, nitrogen, sulfur, and oxygen. Also present in coke is the mineral matter in the original coal, chemically altered and decomposed.

Since the vapor-producing constituents are driven off during coke production, coke is an ideal fuel for stoves and furnaces in which the environment is unsuitable for the complete burning of bituminous coal itself. In the form of oven coke it is primarily used when a porous fuel with few impurities and high carbon content is desired, as in the blast furnaceblast furnace,
structure used chiefly in smelting. The principle involved in this means of extracting metals is that of the reduction of the ores by the action of carbon monoxide, i.e., the removal of oxygen from the metal oxide in order to obtain the metal.
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 to make iron. Coke is also used in other metallurgical processes, such as the manufacture of ferro-alloys, lead, and zinc, and in kilns to make lime and magnesium. Exceptionally large strong coke is known as foundry coke and is used in foundry cupolas to smelt iron ores. The smallest sizes of coke are used to heat buildings.

The majority of coke produced in the United States comes from byproduct coke ovens. The coke is prepared in retorts or furnaces of silica brick, and the byproducts (chiefly ammonia, coal tar, and gaseous compounds) are saved. These volatile gases are collected and sent to the byproduct plant where various byproducts are recovered. In nonrecovery coke plants, originally referred to as beehive ovens, the coal is carbonized in large oven chambers; the partially combusted gases collect in a common tunnel and exit via a stack. In recovery coke plants the waste gas exits into a waste heat recovery boiler which converts the excess heat into steam for power generation.

Petroleum coke is the solid residue left by the cracking process of oil refining. Natural coke, or carbonite, is formed by metamorphismmetamorphism,
in geology, process of change in the structure, texture, or composition of rocks caused by agents of heat, deforming pressure, shearing stress, hot, chemically active fluids, or a combination of these, acting while the rock being changed remains essentially in the
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 from bituminous coal when intrusive igneous rock cuts across a vein of coal.

Coke

 

a man-made solid fuel of high strength; it is produced by heating natural fuels or products of their processing to high temperatures (950°–1050°C) in the absence of air. A distinction is made among coal, pitch, and petroleum coke, depending on the type of the raw material. Most coke is produced from coal.

Coal coke is used mainly in the blast furnace process for smelting iron (metallurgical coke). Here the coke is used simultaneously as a fuel and as an agent for reducing the iron ore. Coke is used in significantly smaller quantities in the foundry process (foundry coke) for the sintering of ores and in the chemical industry and nonferrous metallurgy.

The production of coal coke began in the 18th century, when it became necessary to replace charcoal, which was becoming increasingly scarce, for use in blast furnaces. The first industrial melting with coke was carried out in Great Britain in 1735. By 1970, world coke production was more than 300 million tons per year. In the USSR, which holds first place in coke production, 79.75 million tons were produced in 1972.

Coal coke has the form of elongated gray clumps. True relative density, 1.80–1.95 g/cm3; apparent density, taking the pores into account, 0.8–1.0 g/cm3; average porosity, about 50 percent; bulk weight, 400–500 kg/m3; heat of combustion, about 29 megajoules per kg (MJ/kg, or 7,000 kcal/kg); heat of combustion of combustible mass, about 33 MJ/kg (about 8,000 kcal/kg).

The carbon content in the combustible mass of coke is about 96 percent, and the volatiles yield is 0.8–1.0 percent. The moisture content in coke with dry quenching does not exceed 0.5 percent; with wet quenching, usually 2–4 percent. The sulfur content in metallurgical coke from Donets coals is 1.5–1.9 percent, and from Kuznetsk coals it is 0.4–0.5 percent; for foundry coke, it should not exceed 1.2 percent. The phosphorus content in coke in smelting Bessemer pig iron should not exceed 0.015 percent. The ash content of metallurgical coke should not exceed 9–10.5 percent. As the quantity of these components increases, the quality of the metal deteriorates, the consumption of coke and the charge increases, and the output of the blast furnace is sharply reduced.

Pitch coke and petroleum coke, in comparison with coal coke, have a very low ash content—usually not more than 0.3 percent (up to 0.8 percent for petroleum coke). Pitch coke is produced by coking; high-melting coal-tar pitch in compartment-type Dinas brick ovens. Petroleum coke is produced by coking liquid petroleum residues and pitches in metal coke vats or special furnaces. Petroleum coke is also formed during cracking and pyrolysis of products of petroleum distillation. Pitch coke and petroleum coke are the main raw material for producing electrodes.

REFERENCES

Spravochnik koksokhimika, vol. 2. Moscow, 1965.
Goftman, M. V. Prikladnaia khimiia tverdogo topliva. Moscow, 1963.

D. D. ZYKOV

coke

[kōk]
(materials)
A coherent, cellular, solid residue remaining from the dry (destructive) distillation of a coking coal or of pitch, petroleum, petroleum residues, or other carbonaceous materials; contains carbon as its principal constituent, together with mineral matter and volatile matter.

coke

A contaminant in the lubrication system that is a solid carbon residue left when all the volatile parts of mineral oil have been removed. Coke must be removed from the system.

coke

1. a solid-fuel product containing about 80 per cent of carbon produced by distillation of coal to drive off its volatile constituents: used as a fuel and in metallurgy as a reducing agent for converting metal oxides into metals
2. any similar material, such as the layer formed in the cylinders of a car engine by incomplete combustion of the fuel

Coke

1. Sir Edward. 1552--1634, English jurist, noted for his defence of the common law against encroachment from the Crown: the Petition of Right (1628) was largely his work
2. Thomas William, 1st Earl of Leicester, known as Coke of Holkham. 1752--1842, English agriculturist: pioneered agricultural improvement and considerably improved productivity at his Holkham estate in Norfolk
References in periodicals archive ?
The coking heat treatment has to provide a specific coke structure because a highly graphitized coke has low reactivity and specific heat power (Dumitrescu et.
By the authors opinion, the real configuration of the coke layers/ribbons is very complex and it can be of the vitreous type as it is shown in Fig.
A high oxidation rate of the metallurgical coke to CO and C[O.
The worldwide trend of processing heavy feedstocks in the delayed cokers for getting maximum yield of liquid products has led to the production of fuel grade coke that contains large amounts of sulphur and metals.
The heavier and more contaminated atmospheric and vacuum residues cannot vaporize and eventually end up getting deposited on the surface of the catalyst and tend to increase the production of coke and deactivate the catalyst.
And it isn't until they've actually driven an hour, and Jasmine is sipping her fifteenth Diet Coke, and Passion is trying to maneuver her way around a truck, that one of them finally does speak.
But it's when Jasmine walks to the counter and asks where she can find the Diet Coke in her distinctive voice--smooth and slippery like Kenyatta's yet breezy and sweet like Delores's--that the gas station owner knows.
Extensive studies carried out 20-30 years ago of a large formcoke developed for cupolas indicated that it was more susceptible to degradation by impact and abrasion than conventional coke.
An unpublished portion of their study, however, did find properties equivalent to slot oven coke for a U.
There are many opportunities for key players in the coke, coal and steel industries to be involved in the Eurocoke Summit 2013.
The Met Coke World Summit will take place at the Marriott Pittsburgh City Center in Pittsburgh, PA, USA.
Coke will combust and form ash within the oxygen reach atmosphere of the muffle furnace used for LOI testing.