Aluminum Company of America

J Finley Bush

Paul J The

Gary F Gaydoski

Donald R Mydock

Disclosed in a process for recovering aluminum flouride, caustic, and carbon from spent potlining retrieved from an aluminum electrolytic reduction cell. Spent potlining is treated by leaching with a caustic solution to produce a fluoride-rich basic liquor and carbonaceous solid residue followed by contacting the carbonaceous solid with an acid bath of aluminum sulfate and sulfuric acid to produce a fluoride-rich acid liquor.

Reclaiming spent potlining

A process is described for regeneration of an adsorbent having ammonia adsorbed thereon and comprising a mixture of an alumina and a Y zeolite. The adsorbent may be regenerated to substantially its original capacity for adsorbing ammonia by a two step process which comprises first treating the adsorbent with a saturated solution of an alkali metal carbonate such as sodium carbonate to remove a substantial portion of the ammonia sorbed on the adsorbent mixture and then treating the adsorbent in a second step with a saturated alkali metal bicarbonate solution such as sodium bicarbonate to restore the ammonia adsorption capacity of the adsorbent mixture to substantially its original capacity.

Method for regenerating adsorbent mixture of alumina and zeolite for

Disclosed is a process for dissolving halogen in a bath having an aluminum sulfate/sulfuric acid ratio in the range of about 0.75 to 1.0. The process is useful in extracting fluorine in high yield from spent cell linings recovered from an electrolytic reduction cell for the production of aluminum.

Halogen recovery

A process for the purification of spent liquor from an alumina precipitation stage is disclosed wherein the spent liquor is first contacted with 50 volume % or less ethanol to form a sodium oxalate precipitate and the, after removal of the sodium oxalate precipitate is contacted with over 50 volume % of ethanol extraction fluid to separate the mixture into a first layer comprising the ethanol and at least a portion of the caustic from the spent liquor and a second layer which comprises the remainder of the spent liquor. The spent liquor may then be subjected to a further precipitation to recover further alumina. The spent liquor remaining may be further treated in subsequent extraction steps to concentrate and dispose of undesirable impurities remaining.

Recovery of aluminum from spent liquor

Method for improving yield of solid, sodium-poor fluoride material from an aqueous solution having ionic species containing sodium, aluminum and fluorine, including neutralizing the solution incompletely to precipitate aluminum fluoride hydroxide hydrate in preference to sodium-containing compounds such as chiolite or cryolite.

Aluminum-fluorine compound manufacture

A process is disclosed which provides for the removal of sodium oxalate compounds from a Bayer-type process liquor, after prior precipitation of aluminum hydroxide, which comprises: treating the liquor with ethanol in an amount up to 50 vol. % of the liquor to form a first layer comprising the ethanol and at least a portion of the caustic in the liquor, and a second layer comprising the liquor; and filtering at least the liquor layer to recover a sodium oxalate precipitate. Preferably, the liquor is concentrated to provide a caustic concentration of at least 200 and, most preferably, about 250 grams per liter total caustic (measured as sodium carbonate).

Process for the removal of sodium oxalate compounds from Bayer spent

In accordance with the invention, spent liquor from an alumina precipitation stage is contacted with an extraction fluid to separate the mixture into a first layer comprising the extraction fluid and at least a portion of the caustic from the spent liquor and a second layer which comprises the remainder of the spent liquor. The spent liquor may then be subjected to a further precipitation to recover further alumina. The spent liquor remaining may be further treated in subsequent extraction steps to concentrate and dispose of undesirable impurities remaining.

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New Kensington, PA, United States of America

J Finley Bush