Abstract: A cascading bed retorting process and apparatus in which cold raw crushed shale enters at the middle of a retort column into a mixer stage where it is rapidly mixed with hot recycled shale and thereby heated to pyrolysis temperature. The heated mixture then passes through a pyrolyzer stage where it resides for a sufficient time for complete pyrolysis to occur. The spent shale from the pyrolyzer is recirculated through a burner stage where the residual char is burned to heat the shale which then enters the mixer stage.

Abstract: A cascading bed retorting process and apparatus in which cold raw crushed shale enters at the middle of a retort column into a mixer stage where it is rapidly mixed with hot recycled shale and thereby heated to pyrolysis temperature. The heated mixture then passes through a pyrolyzer stage where it resides for a sufficient time for complete pyrolysis to occur. The spent shale from the pyrolyzer is recirculated through a burner stage where the residual char is burned to heat the shale which then enters the mixer stage.

Abstract: A combustion heater for oil shale heats particles of spent oil shale containing unburned char by burning the char. A delayed fall is produced by flowing the shale particles down through a stack of downwardly sloped overlapping baffles alternately extending from opposite sides of a vertical column. The delayed fall and flow reversal occurring in passing from each baffle to the next increase the residence time and increase the contact of the oil shale particles with combustion supporting gas flowed across the column to heat the shale to about 650.degree.-700.degree. C. for use as a process heat source.

Abstract: In an in situ oil shale retorting process, plastic flow of hot rubblized oil shale is minimized by injecting carbon dioxide and water into spent shale above the retorting zone. These gases react chemically with the mineral constituents of the spent shale to form a cement-like material which binds the individual shale particles together and bonds the consolidated mass to the wall of the retort. This relieves the weight burden borne by the hot shale below the retorting zone and thereby minimizes plastic flow in the hot shale. At least a portion of the required carbon dioxide and water can be supplied by recycled product gases.

Abstract: A method for rubblizing an oil shale deposit that has been formed in alternate horizontal layers of rich and lean shale, including the steps of driving a horizontal tunnel along the lower edge of a rich shale layer of the deposit, sublevel caving by fan drilling and blasting of both rich and lean overlying shale layers at the distal end of the tunnel to rubblize the layers, removing a substantial amount of the accessible rubblized rich shale to permit the overlying rubblized lean shale to drop to tunnel floor level to form a column of lean shale, performing additional sublevel caving of rich and lean shale towards the proximate end of the tunnel, removal of a substantial amount of the additionally rubblized rich shale to allow the overlying rubblized lean shale to drop to tunnel floor level to form another column of rubblized lean shale, similarly performing additional steps of sublevel caving and removal of rich rubble to form additional columns of lean shale rubble in the rich shale rubble in the tunnel, an