Spent shale explained

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.^{[1] [2]} According to the European Union waste list all these types of spent shale are classified as hazardous waste.^[2]

Oil shale coke is created by chamber ovens which were used for oil shale gas production.^[1] 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.^[3]

Spent shale can be used as ingredients in cement or brick manufacture.^{[1] [4] [5]} In Jordan, usage of spent shale for the production of sodium carbonate, ammonium sulfate, and potassium sulfate has been studied.^[6]

Notes and References

1. Veski . R. . The Volumes of Spent Oil Shale from Estonian Oil-Shale Processing Units for the Period of 1921–2002 . Oil Shale. A Scientific-Technical Journal . Estonian Academy Publishers . 22 . 3 . 345–357 . 2005 . PDF . 0208-189X . 2008-10-25.
2. Habicht . Jaan . Orupõld . Kaja . Retorted Oil Shale In Estonia: An Environmental Audit . . 27th Oil Shale Symposium . . PDF . 2007-10-15 . 2014-11-27.
3. Mõtlep . R. . Kirsimäe . K. . Talviste . P. . Puura . E. . Jürgenson . J. . Mineral composition of Estonian oil shale semi-coke sediments . Oil Shale. A Scientific-Technical Journal . Estonian Academy Publishers . 24 . 3 . 405–422 . 2007 . PDF . 0208-189X . 2014-11-27.
4. Koel. Mihkel . Estonian oil shale . . Estonian Academy Publishers . Extra . 1999 . 0208-189X . 2007-07-21.
5. Qian . Jialin . Wang . Jianqiu . Li . Shuyuan . One Year's Progress in the Chinese Oil Shale Business . . 27th Oil Shale Symposium . . PDF . 2007-10-15 . 2011-05-06.
6. Resheidat . Musa . Al-Shyoukh . Ali . Khair Al-Nawasrah . Mohammad . 27th Oil Shale Symposium . On the Use of Oil Shale beyond the Production of Oil and Gas . . PDF . 2007-10-15 . 2022-04-11.