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Abstract

A method and apparatus for the extraction of hydrocarbon products, alumina and soda ash from oil shales including various amounts of such chemicals, all based on solvent extraction of most of the hydrocarbons at temperatures around 400.degree. C. Such enables the alumina and soda ash values to be leached out with aqueous sodium carbonate leaching at reduced temperatures of around 150.degree. C. with a corresponding reduced pressure. The soda ash monohydrate values are precipitated from the leach liquor at around 100.degree. C. with the alumina values precipitated using CO.sub.2. Alternatively recycled fine aluminum trihydrate at 65.degree. C. is used to produce alumina. Aluminum hydroxide is converted to acid alumina by an acid recycle stream that dissolves the alumina so any silica contaminant can be filtered out. Basic aluminum sulfate is then precipitated at about 200.degree. C. and 250 PSIG for subsequent calcination at around 900.degree. C. This produces alumina and sulphate oxide gasses are recycled via a sulphuric-acid plant.

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