Shale oil and mineral recovery process

Claim 2

A process according to claim 1 wherein precipitating the aluminum hydroxide from the caustic leach liquor includes the adding of CO2.

Claim 3

A process according to claim 1 wherein precipitating the aluminum hydroxide includes seeding of the leach liquor

Claim 4

A process according to claim 1 wherein the spent shale from the retort is burned at a controlled heat at a temperature ranging from above about 450*C. to about 600*C. before being subjected to the caustic leach.

Claim 5

A process according to claim 1 wherein the caustic leach comprises a solution of sodium carbonate of a concentration in a range of about 0.1 to 0.5 Normal.

Claim 6

A process according to claim 1 wherein the caustic leach also contains sodium hydroxide to maintain the pH not exceeding about 12.2 and not below about 11.

Claim 7

A process according to claim 1 wherein the spent shale from the retort is burned after the caustic leach to provide heat to the process and to provide a source of CO2 for precipitating the aluminum hydroxide from the leach liquor of the caustic leach.

Claim 8

A process according to claim 8 wherein the spent shale is subjected to grinding before the caustic leach, to remove carbon coating the shale particles.

Claim 9

A process according to claim 1 wherein the oil shale includes aluminum in the form of a major portion of dawsonite and a minor portion of at least gibbsite.

Claim 10

A process according to claim 1 wherein sodium carbonate is recovered from the leach liquor of the caustic leach by filtering and evaporating the caustic leach liquor to recover sodium carbonate.

Claim 11

A process according to claim 1 wherein the quantity of nahcolite remaining in the shale after the aqueous leach does not exceed an amount sufficient to cause the sodium carbonate concentration in the caustic leach to be greater than about 0.5 Normal.

Claim 12

A process according to claim 1 wherein at least about three-fourths of the original nahcolite is removed from the oil shale by screening, and at least about three-fourths of the then remaining nahcolite is removed by by aqueous leach.

Claim 13

A process according to claim 1 wherein the step of mechanically separating includes a two-stage crushing seQuence, with the screening being done between crushing steps.

Claim 14

A process according to claim 1 wherein the step of mechanically separating includes at least a two-stage crushing sequence followed by screening.

Claim 15

An integrated process for producing hydrocarbon products, sodium carbonate, and aluminum compounds from oil shale containing oil, nahcolite, and dawsonite, comprising the steps of: initially heating the oil shale at a temperature less than pyrolizing temperature to decompose the nahcolite to sodium carbonate; impacting the heated shale to disintegrate the particles of sodium carbonate relative to the host shale; segregating the sodium carbonate from the host shale on the basis of particle size, and collecting the particles of sodium carbonate; retorting the crushed shale to recover hydrocarbon products and to convert the dawsonite to a more soluble aluminum compound; leaching the spent shale from the retort in a weak caustic leach containing no more than about 0.5 Normal solution of sodium carbonate, and having no more than about 6 moles of sodium per mole of available aluminum, to dissolve the aluminum compound; separating the spent shale from the caustic leach liquor containing the dissolved aluminum compound; precipitating aluminum hydroxide from the caustic leach liquor; separating the aluminum hydroxide precipitate from the caustic leach liquor; and removing sodium carbonate from the caustic leach liquor by evaporation.

Claim 16

A process according to claim 16 wherein the particles of sodium carbonate are further separated from the host shale by a floatation step following the segregating step.

Claim 17

A process according to claim 16 further comprising converting the aluminum hydroxide to alumina by calcining.

Claim 18

A process according to claim 16 wherein precipitation of aluminum hydroxide includes adding CO2 to the leach liquor.

Claim 19

A process according to claim 16 wherein precipitation of aluminum hydroxide includes seeding.

Claim 20

A process according to claim 16 wherein the initial heating is at a temperature of from about 100*C. to about 475*C. for a time less than would cause significant pyrolizing of the oil shale.

Claim 21

A process according to claim 16 wherein the retorting is in a non-combustion type retort at a temperature not greater than about 550*C.

Claim 22

A process according to claim 16 wherein the spent shale from the retort is burned at a temperature not exceeding about 600*C. prior to leaching.

Claim 23

A process according to claim 16 wherein the caustic leach has a pH not exceeding about 12.2.

Claim 24

A process according to claim 16 wherein part of the sodium carbonate in the leach liquor is from nahcolite passing through the crushing and retorting steps.