Spent shale or spent oil shale (also known as retorted shale) is a solid residue from the shale oil extraction process of producing synthetic

shale oil Shale oil is an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock (kerogen) into synthetic oil and gas. The resulting oil ca ...

from oil shale. It consists of

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

s (

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...

s) and remaining

organic matter Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...

known as

char Char may refer to: People *Char Fontane, American actress *Char Margolis, American spiritualist * René Char (1907–1988), French poet *The Char family of Colombia: ** Fuad Char, Colombian senator ** Alejandro Char Chaljub, mayor of Barranquilla ...

—a

carbonaceous Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—its atom making four electrons available to form covalent bond, covalent chemical bonds. It belongs to gro ...

residue formed from kerogen. Depending on the extraction process and the amount of remaining organic matter, spent shale may be classified as oil shale coke, semi-coke or coke-ash residue, known also as oil shale ash. According to the European Union waste list all these types of spent shale are classified as hazardous waste. Oil shale coke is created by chamber ovens which were used for oil shale gas production. Vertical retorts create mainly semi-coke. Most solid heat carrier processes create coke-ash residue as the semi-coke created during the process is combusted for the process's energy needs. Spent shale can be used as ingredients in cement or brick manufacture. In

Jordan Jordan ( ar, الأردن; tr. ' ), officially the Hashemite Kingdom of Jordan,; tr. ' is a country in Western Asia. It is situated at the crossroads of Asia, Africa, and Europe, within the Levant region, on the East Bank of the Jordan Rive ...

, usage of spent shale for the production of

sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...

, ammonium sulfate, and potassium sulfate has been studied.

References

{{Reflist, 30em Oil shale Hazardous waste