Petrosix is the world's largest surface oil shale pyrolysis retort with an 11 metres (36 ft) diameter vertical shaft kiln, operational since 1992.
A 5.5 metres (18 ft) inside diameter semi-works retort (the Irati Profile Plant) with capacity of 2,400 tons per day, was brought on line in 1972, and began limited commercial operation in 1980.
A 11 metres (36 ft) retort was brought into service in December 1991, and commercial production started in 1992.
[1][2] The Petrosix 11 metres (36 ft) vertical shaft retort is the world's largest operational surface oil shale pyrolysis reactor.
[2] It is an above-ground retorting technology, which uses externally generated hot gas for the oil shale pyrolysis.
Cold gas is injected into the bottom of the retort to cool and recover heat from the spent shale.