**Historical Development**:
– Chinese historical sources from the 4th century mention coke production.
– Chinese ironworkers in the 11th century began using coke to fuel furnaces.
– By 1078 CE, coke replaced charcoal in iron production in China.
– In 1589, a patent was granted in Britain for making iron and steel with coke.
– Abraham Darby I established a coke-fired blast furnace in Britain in 1709.
– The US saw its first use of coke in an iron furnace around 1817.
– China is the largest producer and exporter of coke, accounting for 60% of global production.
– By 1880, Britain produced about 7,000,000 tons of coke per year.
**Production and Industrial Impact**:
– Coke was produced by heating coal in enclosed chambers in gas works.
– Improvement in coke production processes increased yields from 33% to 65% by the 19th century.
– Availability of inexpensive iron due to coke was a factor in the Industrial Revolution.
– Coke allowed blast furnaces to become taller and larger.
– Transition from charcoal to coke in iron-making was essential due to deforestation.
– Coke played a crucial role in the expansion of the iron industry in Britain and the US.
– Industrial coke furnaces use a coke oven to produce coke from coal at high temperatures.
**Occupational Safety and Environmental Impact**:
– Exposure to coke oven emissions in the workplace can occur through inhalation, skin contact, or eye contact.
– Legal exposure limits for coke oven emissions are set by OSHA and NIOSH in the US.
– Wastewater from coking is highly toxic and carcinogenic.
– Various methods for treatment of coking wastewater have been studied.
– Environmental damage from beehive coking in the US attracted national attention after 1900.
**Uses and Properties**:
– Coke can be used as fuel and a reducing agent in smelting iron ore.
– Coke is commonly used in blacksmithing and as a smokeless fuel in stoves and furnaces.
– Coke has a bulk specific gravity of around 0.77 and is highly porous.
– Low ash and sulfur content are desirable in coke production.
– Important characteristics include M10, M25, and M40 test crush indexes.
– Coke Strength After Reaction (CSR) index shows cokes ability to withstand blast furnace conditions.
**Byproducts and Other Processes**:
– Byproducts of coking include coal tar pitch, ammonia, hydrogen sulphide, pyridine, and carbon-based material.
– Various industries use petroleum coke, a solid residue from petroleum refining.
– Gas works producing syngas also generate coke.
– Fluid coking converts heavy crude into lighter products.
– High-temperature lignite coke is produced from low-quality lignite.
Coke is a grey, hard, and porous coal-based fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air—a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.
The unqualified term "coke" usually refers to the product derived from low-ash and low-sulphur bituminous coal by a process called coking. A similar product called petroleum coke, or pet coke, is obtained from crude oil in oil refineries. Coke may also be formed naturally by geologic processes.