{{Short description|Solid residue from the shale oil extraction process}} {{Redirect|Semi-coke|a fuel made from coal|Coke (fuel)|a solid residue derived from distillation of crude oil|Petroleum coke}} right|thumb|Mounds of spent shale|alt=A photograph of dark gray/silver piles of spent shale lumps. '''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 from oil shale. It consists of inorganic compounds (minerals) and remaining organic matter known as char—a carbonaceous 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.<ref name=veski2> {{Cite journal | last = Veski | first = R. | title = The Volumes of Spent Oil Shale from Estonian Oil-Shale Processing Units for the Period of 1921–2002 | journal = Oil Shale. A Scientific-Technical Journal | publisher = Estonian Academy Publishers | volume = 22 | issue = 3 | pages = 345–357 | year = 2005 | url = http://www.kirj.ee/public/oilshale/oil-2005-3-veski.pdf | format = PDF | issn = 0208-189X | accessdate = 2008-10-25 }}</ref><ref name=habicht> {{Cite conference | last1 = Habicht | first1 = Jaan | last2 = Orupõld | first2 = Kaja | title = Retorted Oil Shale In Estonia: An Environmental Audit | publisher = Colorado School of Mines | conference = 27th Oil Shale Symposium | location = Golden, Colorado | url= http://www.ceri-mines.org/documents/27symposium/presentations/av08-1habicht.pdf | archive-url= https://web.archive.org/web/20141204213109/http://www.ceri-mines.org/documents/27symposium/presentations/av08-1habicht.pdf | url-status= usurped | archive-date= December 4, 2014 | format = PDF | date = 2007-10-15 | accessdate =2014-11-27}} </ref> According to the European Union waste list, all these types of spent shale are classified as hazardous waste.<ref name=habicht/>
Oil shale coke is created by chamber ovens which were used for oil shale gas production.<ref name=veski2/> 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.<ref name=motlep> {{Cite journal | last1 = Mõtlep | first1 = R. | last2 = Kirsimäe | first2 = K. | last3 = Talviste | first3 = P. | last4 = Puura | first4 = E. | last5 = Jürgenson | first5 = J. | title = Mineral composition of Estonian oil shale semi-coke sediments | journal = Oil Shale. A Scientific-Technical Journal | publisher = Estonian Academy Publishers | volume = 24 | issue = 3 | pages = 405–422 | year = 2007 | url = http://www.kirj.ee/public/oilshale/oil-2007-3-2.pdf | format = PDF | issn = 0208-189X | accessdate = 2014-11-27 }}</ref>
Spent shale can be used as ingredients in cement or brick manufacture.<ref name=veski2/><ref name=koel> {{Cite journal |last=Koel|first=Mihkel | title=Estonian oil shale | journal =Oil Shale. A Scientific-Technical Journal | publisher=Estonian Academy Publishers | issue=Extra | year=1999 | url=http://www.kirj.ee/public/oilshale/Est-OS.htm | issn=0208-189X | accessdate=2007-07-21}} </ref><ref name=qian3> {{Cite conference | last1 =Qian | first1 =Jialin | last2 =Wang | first2 =Jianqiu | last3 =Li | first3 =Shuyuan | title = One Year's Progress in the Chinese Oil Shale Business | publisher = Colorado School of Mines | conference = 27th Oil Shale Symposium | location = Golden, Colorado | url= http://www.ceri-mines.org/documents/27symposium/presentations/av02-1qian.pdf | archive-url= https://web.archive.org/web/20110912031140/http://www.ceri-mines.org/documents/27symposium/presentations/av02-1qian.pdf | url-status= usurped | archive-date= September 12, 2011 | format = PDF | date = 2007-10-15 | accessdate =2011-05-06}} </ref> In Jordan, usage of spent shale for the production of sodium carbonate, ammonium sulfate, and potassium sulfate has been studied.<ref name=resheidat> {{Cite conference | last1 = Resheidat | first1 = Musa | last2 = Al-Shyoukh | first2 = Ali | last3 = Khair Al-Nawasrah | first3 = Mohammad | conference = 27th Oil Shale Symposium | title = On the Use of Oil Shale beyond the Production of Oil and Gas | location = Golden, Colorado | url= https://www.researchgate.net/publication/242367135_On_the_Use_of_Oil_Shale_beyond_the_Production_of_Oil_and_Gas | format = PDF | date = 2007-10-15 | accessdate =2022-04-11}} </ref>
==References== {{Reflist|30em}}
Category:Oil shale Category:Hazardous waste