Process and apparatus for solvent extraction of oil from oil-containing diatomite ore

Claim 1

A process for continuous extraction of oil from diatomite ore with a hydrocarbon solvent comprising: (a) mixing oil-containing diatomite ore and a second miscella previously produced in the operation of the process to form a slurry; (b) charging the slurry to a settling zone wherein a first miscella, containing oil and solvent and ore fines, is separated from the diatomite; (c) contacting said separated diatomite with solvent in a plurality of countercurrent extraction stages and extracting oil therefrom, and separating a second miscella, containing oil and solvent, from spent diatomite containing residual solvent; (d) returning the second miscella to step (a) for mixing with oil-containing diatomite ore; (e) intimately mixing the spent diatomite containing residual solvent with water; (f) separating the mixture so formed into two phases, a heavier phase comprising an aqueous slurry of spent diatomite containing a minor amount of solvent and a lighter solvent phase; (g) stripping the minor amount of solvent from said aqueous slurry of spent diatomite as a first vapor by contact with steam at superatmospheric pressure; (h) condensing the mixture of first solvent vapor and steam removed by said stripping and separating the condensate into water and recovered solvent phases; (i) evaporating solvent from said first miscella as a second solvent vapor, to recover substantially solvent free oil; (j) condensing the second solvent vapor; and (k) returning said lighter solvent phase of step (f) and the first and second condensed solvent vapors to the countercurrent extraction stages.