PURPOSE: To balance the calorie and the gas flow rate in an apparatus wherein the dry distillation is carried out while an oil-containing mineral is moving under its own weight through four columns forming separate fluidized beds, i.e. a preheating column, a dry-distillation column, a burning column and a cooling column, by returning part of the fine powdery and granular solid in the burning column to the dry-distrillation column.

CONSTITUTION: An oil-containing mineral is introduced from a feed port 9 into a preheating column 1 where it is preheated, and then moves through a descending pipe 5 to a dry-distillation column 2 under its own weight. The solid that has been heated by a heating gas 12 moves though a descending pipe 6 to a burning column 3 where air 14 is introduced from the lower part and the uncarbonized solid is burnt. In the column 3, the solids having relatively large sizes are tansferred to the column 2 and on the other hand the remaining solid part is transferred to a cooling column 4 through a descending pipe 8. As the granular solids transferred to the column 2 is at a high temperature due to the combustion of the uncarbonized material, its sensible heat goes to the oil-containing mineral in the column 2 to facilitate the dry-distrillation. By adjusting the inflow rate of the heating gas 12 and the transferring rate of the granular solids via the descending pipe 7, the dry-distillation can be carried out efficiently.