Clinker is a general name given to waste from industrial processes, particularly those that involve

smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ...

metals,

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as bra ...

, burning fossil fuels and use of a

blacksmith A blacksmith is a metalsmith who creates objects primarily from wrought iron or steel, but sometimes from other metals, by forging the metal, using tools to hammer, bend, and cut (cf. tinsmith). Blacksmiths produce objects such as gates, gr ...

's forge, which commonly causes a large buildup of clinker around the

tuyere A tuyere or tuyère (; ) is a tube, nozzle or pipe through which air is blown into a furnace or hearth.W. K. V. Gale, The iron and Steel industry: a dictionary of terms (David and Charles, Newton Abbot 1972), 216–217. Air or oxygen is in ...

. Clinker often forms a loose, dark deposit consisting of waste materials such as coke,

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

, slag, charcoal, and grit. Clinker often has a glassy look to it, usually because of the formation of molten

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

compounds during processing. Clinker generally is much denser than coke, and, unlike coke, generally contains too little carbon to be of any value as fuel.

Etymology

"Clinker" is from Dutch, and was originally used in English to describe

clinker brick Clinker bricks are partially-vitrified bricks used in the construction of buildings. Clinker bricks are produced when wet clay bricks are exposed to excessive heat during the firing process, sintering the surface of the brick and forming a shin ...

s. The term was later applied to hard residue, due to its similar appearance.

Uses

Clinker often is reused as a cheap material for paving footpaths. It is laid and rolled, and forms a hard path with a rough surface that presents less risk of slipping than most loose materials. In sufficient thickness such a layer drains well and is valuable for controlling muddiness. However, if laid without sufficient adhesive, it needs frequent rolling and addition of more clinker to maintain the path in good condition if it is subject to heavy foot traffic. In

sewage treatment Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding e ...

works, the foul water first is screened to remove floating debris. Then it is sedimented to remove insoluble particles. After this, it is sprayed over a filter bed of clinker. Aerobic microbes soon grow in hollows in the clinker, where they kill harmful anaerobic bacteria in the water and remove much of the offensive organic waste. Historically, clinker from coal-burning steamships simply was discarded overboard, leaving detectable trails on the seabed of some prominent steamship routes. As such, the deposits have proven to be of both biological and archaeological interest.

References

{{DEFAULTSORT:Clinker (Waste) Waste Metallurgical processes

Etymology

Uses

See also

References