The particularity of this process is that it use hot ceramic balls for the heat transfer between the retort and a heater.
[3] In 1964 Tosco, Standard Oil of Ohio, and Cleveland Cliffs Iron Company formed Colony Development, a joint venture company to develop the Colony Shale Oil Project and to commercialize the TOSCO II technology.
[5] After entering into retort, oil shale is mixed with hot ceramic balls with temperature from 1,200 °F (650 °C) to 1,600 °F (870 °C).
The process' other disadvantages are mechanical complexity and large number of moving parts.
Disposal of spent shale includes environmental problems because it is very finely crushed and contains carbon residue.