Recovery of hydrocarbons from hydrocarbon contaminated sludge

Claim 1

A process for recovering hydrocarbons from hydrocarbon contaminated sludge containing particulate solid material, said sludge comprising hydrocarbon wetted solid material selected from the group consisting of coarse sand, fine sand, clays, gravels and mixtures thereof, said process comprising adding water if necessary to said sludge containing particulate solid material to produce a slurry with a pulp density in the range of from about 30 to about 50% by weight solids, subjecting the slurry to mechanical action in a grinding medium in a slurry preparation step for a time sufficient to disengage the hydrocarbon from the solid material and cause entry of the hydrocarbon into a water phase, and removing oversize solids from the prepared slurry if necessary, diluting the slurry to less than 30% by weight solids by addition of water, aerating the diluted slurry to cause air bubbles to attach to the hydrocarbon and feeding the aerated slurry to a pneumatic cyclonic separation vessel having a rotating body of said slurry to cause the aerated slurry to enter said vessel substantially tangentially in a substantially horizontal plane into the rotating body of said slurry to cause the slurry in said vessel to circulate therein in a cyclonic manner with the hydrocarbon being floated by the attached air bubbles to form a froth on top of the slurry in the vessel and with the solids sinking to the bottom of the vessel, and, removing the hydrocarbon-containing froth from the top of the vessel and removing the essentially hydrocarbon-free solids from the bottom thereof.