Abstract: This invention relates to a method of improving the dewatering of alumina trihydrate obtained by the Bayer process. The method comprises treating the alumina trihydrate with the product of mixing an alkaline liquor and a C.sub.8 to C.sub.20 fatty acid, fatty acid precursor such as an ester or amide, or a fatty acid blend. The product, a fatty acid salt, is an effective dewatering aid.The alumina trihydrate may be washed with a liquor including said product, or the product may be added to a Bayer liquor slurry prior to filtration of the alumina trihydrate.The invention also contemplates a watering aid consisting of the product of mixing an alkaline liquor with a C.sub.8 to C.sub.20 fatty acid or fatty acid precursor.

Abstract: A process for the production of large boehmite crystal aggregates, useful for soft polishing applications is provided herein. A caustic aluminate liquor is contacted with an oxygen-containing gas at elevated temperatures and pressures in the presence of about 1-50 mg/L of copper ions. The liquor is oxidized until a molar ratio of Na.sub.2 O.sub.free to Al.sub.2 O.sub.3 of less than or equal to 1 is achieved, and the oxidized liquor is cooled under quiescent conditions of little or no agitation which causes the crystallization and precipitation or novel large boehmite particles.

Abstract: The present invention provides a process for treating spent potlining from the electrolytic smelting of aluminum in cryolite including burning the spent potlining to form an ash, mixing with a siliceous material either before or after the ash-forming step, and heating to form a residue suitable for landfill. The ash and siliceous material are mixed in a specified mole ratio of at least about 1.4 silicon to sodium. The process further includes cooling the residue rapidly.The residue formed by the process of the present invention produces a spent potlining suitable for landfill characterized by a low leachability of fluorine in water.

Abstract: The present invention provides a process for the production of fine, tabular boehmite crystals substantially within the size range of 0.2-0.8 microns. The crystals are particularly suitable for use as a pigment/filler in paper, paint and ink applications.

Abstract: A basic liquid ion exchange process in which a side stream of Bayer liquor is treated with a cationic compound preferably in the form of a polymer (poly-DADMAC) to extract a significant amount of the organic contaminants (humates) from the liquor. The contaminant loaded organic layer is separated from the treated liquor (which is returned to the system) and stripped by an alkali metal precipitation technique and the polymer is regenerated.

Abstract: A process for purifying anhydrous aluminum chloride containing organochlorine impurities, comprising contacting said impure aluminum chloride with a bath containing at least one chloroaluminate for a time sufficient to remove said impurities therefrom and recovering the purified aluminum chloride in the vapor phase of the chloroaluminate bath.

Abstract: Methods for forming or purifying organometallic compounds of elements of Group III-A of the Periodic Table. An intermediate compound is formed which is an adduct of the desired organometallic compound and a Group I-A or Group II-A compound. The adduct is nonvolatile, so volatile impurities are removed from the adduct by distillation. The adduct is decomposed to release the volatile organometallic compound, which is then distilled away from the nonvolatile remainder of the adduct. The method can be used to produce organometallic compounds which are substantially free of volatile metallic compounds and complexed solvents. A method of separating volatile Group II-B impurities from volatile Group III-A compounds is also disclosed.

Abstract: A liquor of the Bayer process, as defined, is contacted with manganese dioxide to oxidize organic material in the liquor. When the liquor is the seed wash liquor, oxalates in particular are oxidized.

Abstract: A process for producing aluminum hydroxide product having an improved level of whiteness is disclosed. In the process, a caustic solution having dissolved aluminum hydroxide is subjected to purification to remove color producing humate material. Purification includes passing the caustic solution through a semi-permeable membrane. The solution purified of humate material is treated to precipitate aluminum hydroxide therefrom.

Abstract: Thermally decomposable Group IIIa compounds are purified by conveying the relatively impure material through a prescrubber module, then heating the scrubbed Group IIIa compound and conveying same through a preconditioned gas chromatographic column packed with a porous polymeric material. After isolation, the purified material is cooled, demisted amd collected. Thermally decomposable Group Va compounds are purified by conveying the heated relatively impure material through a preconditioned gas chromatographic column packed with a porous polymeric material. After isolation, the purified material is cooled and collected.

Abstract: A method and composition for producing a more coarse alumina trihydrate crystal in a Bayer process pregnant liquor, involving the addition of approximately 5-400 mg/l of surfactant-oil, the oil dissolving the surfactant which can be selected from a host of surfactants which are stable in (hot) caustic solutions and capable of dispersing hydrophobic liquids in the Bayer liquor. The preferred embodiment involves the use of tall-oil fatty acids; a number of equivalent surfactants are established. The oil or hydrocarbon (hydrophobic) liquid can be selected from paraffinic oils, naphthenic oils, mineral seal oils, fuel oils, and bottoms or residue from a C.sub.10 alcohol distillation.

Abstract: Hazardous waste containing inorganic compounds which contain heavy metals or particular hazardous anionic groups or which are hazardous halides or non-metal oxides or sulfides is contacted with molten aluminum to provide reduction to lower less hazardous oxidation state.

Abstract: A system is disclosed for the purification of a caustic solution to remove impurities therefrom comprises: bringing the caustic solution into contact under pressure with the outside of a plurality of porous hollow fibers each having at least one open end and coated with a semipermeable membrane and collecting purified solution from the open ends of the hollow fibers. In a preferred embodiment, the filtering medium comprises porous hollow polysulfone fibers coated with a semipermeable sulfonated polysulfone membrane.

Abstract: A process for producing aluminum hydroxide product having an improved level of whiteness is disclosed. In the process, a caustic solution having dissolved aluminum hydroxide is subjected to purification to remove color producing humate material. Purification includes passing the caustic solution through a semi-permeable membrane. The solution purified of humate material is treated to precipitate aluminum hydroxide therefrom.

Abstract: The present invention is directed to a method for removing organic substances from aluminate liquors of the Bayer process. The method comprises the steps of contacting the liquor with an oxygen containing gas under elevated pressure in the presence of metallic ions acting as a catalyst to oxidize the organic substances, precipitating the metallic ions jointly with aluminum hydroxide, separating the precipitate from the oxidized liquor and recycling the precipitated aluminum hydroxide containing the metallic ions into the oxidation step as a catalyst carrier.

Abstract: In a method of processing contaminated sodium oxalate which becomes available in a separating stage succeeding the digestion of bauxite in accordance with the Bayer process, chemicals used in the digesting process are recovered in that moist sodium oxalate which has been separated is dried with the hot exhaust gases from a rotary kiln jointly with aluminum hydroxide or aluminum oxide hydrate and/or reactive alumina at a mole ratio of aluminum to sodium of at least 0.8 and the dried product is decomposed in said rotary kiln at a temperature of 780.degree. to 1000.degree. C. to form sodium aluminate. Suitably drying is effected by spray drying in direct contact with the exhaust gases of the rotary kiln and decomposition is effected at a temperature in the range from 850.degree. to 950.degree. C. and with an Al:Na ratio not in excess of 1.2.

Abstract: High molecular weight organic compounds, such as humic acid derivatives, are removed from Bayer process caustic liquors by oxidation of these compounds. The process involves addition of oxygen to the caustic liquor in quantities in the range established by the solubility of the oxygen in the liquor under the oxidation conditions.

Abstract: Process for the low-temperature treatment according to the Bayer cycle of gibbsite-bearing bauxite of low reative silica content, involving desilication of the said bauxite before leaching, by a liquor of low caustic soda concentration and characterized in that this sodium liquor consists of one or more washing waters originating from the Bayer cycle, mixed or otherwise with leaching liquor, wherein the weighted reactive silica content is preferably lower than 5% of the alumina content of the bauxite and the concentration of the sodium liquor used for desilication ranges from 50 to 120 g/liter of Na.sub.2 O caustic.

Abstract: In a method for processing contaminated sodium oxalate which becomes available in a separating stage succeeding the digestion of bauxite in accordance with the Bayer process, chemicals used in the digesting process are recovered in that the moist sodium oxalate which has been separated is dried with the hot exhaust gases from a fluidized bed, particularly a circulating fluidized bed, jointly with aluminum hydroxide or aluminum oxide hydrate and/or reactive alumina at a mole ratio of aluminum to sodium of at least 0.8 and the dried product is decomposed in said fluidized bed at a temperature of 780.degree. to 1000.degree. C. to form sodium aluminate. Suitably drying is effected by spray drying in direct contact with the exhaust gases of the fluidized bed and decomposition is effected at a temperature in the range from 850.degree. to 950.degree. C. and with an Al:Na mole ratio not in excess of 1.2.

Abstract: The negative effects of sodium oxylate on the crystallization of aluminum trihydrate from Bayer process liquors may be eliminated or curtailed by adding an effective amount of a polyacrylic acid with a molecular weight about 1,000,000 and containing at least 50 mole percent acrylic acid monomer to pregnant Bayer process liquors.

Abstract: A process for purifying at least a fraction of a solution in the Bayer cycle, which is preferably taken off after decomposition of the sodium aluminate, before or after concentration thereof, by causing the precipitation of the sodium oxalate in solution by the introduction of an agent for destabilization of the state of supersaturation of the sodium oxalate, which is characterized in that the supersaturation destabilization agent introduced into the Bayer solution to cause precipitation of the sodium oxalate is selected from the group comprising calcium oxalate and barium oxalate and that, in the case of solutions charged with degraded organic materials which generally result from high-temperature attack on bauxites with high proportions of humic materials, an anionic synthetic polyelectrolyte of high molecular mass is previously introduced into said solutions in order to increase the efficiency of the purification effect.

Abstract: A method for producing a kerogen concentrate from oil shale comprises treating shale with a first aqueous caustic treating solution to produce a shale product of substantially transformed mineral content, and then treating the shale product with an aqueous acid solution to produce a first kerogen concentrate. The acid solution extracts minerals from the shale product to make a low ash content first kerogen concentrate. A spent acid solution containing the extracted minerals can be treated to recover minerals therefrom. The first kerogen concentrate is then treated with a second aqueous caustic treating solution to produce a second kerogen concentrate of lower ash content. The first and second aqueous caustic treating solutions are preferably the same.

Abstract: Wet oxidation of organic contaminants in aqueous sodium aluminate solutions is enhanced when a heated and oxygenated solution is passed through a packed bed containing a metal packing member that is chemically inert to sodium aluminate solutions at elevated temperatures. Process temperature is about 180.degree.-300.degree. C. and oxygen partial pressure is at least about 345 kPa. The packed bed has a packing surface of at least 100 square meters per cubic meter bed volume and preferably at least 50% free space.

Abstract: 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.

Abstract: Bayer process liquors derived from the digestion of bauxites with a caustic solution are purified by removing at least a portion of the organic impurities present in the liquors. Removal of these impurities is accomplished by treating liquor containing dispersed therein solids generated by the Bayer process or added thereto, such as red mud particles, alumina trihydrate, oxalate salt, or filter aid with an organic polymeric, water-soluble cationic quaternary ammonium salt (POLYQUAT salt) which due to its cationic nature will adhere to the surface of the dispersed solids. The organic coating or layer adhered to the solids provides a receptive surface for the organic impurities, thus allowing formation of a solid-Polyquat-organic Adduct which is easily removed from the Bayer system.

Abstract: Waste-containing (contaminated) waters are treated for reuse and disposal with acceptable environmental improvements by adding a sulfate salt of aluminum and/or iron alkalized to form a waste-cohering hydroxide floc in one or more treatment plants, recovering the flocs and wastes by contacting with sulfur oxides to redissolve the aluminum and/or iron for reuse, in which case low cost sulfur containing fuels are utilized to provide heat and sulfur for recovering over one-half of the sulfur dioxide for reuse and reducing the lime required to neutralize the acidity.

Abstract: Aluminum dross containing chlorides and combustible volatile material is agglomerated and sized to produce a compact which is then treated in a direct fired rotary kiln in excess of 1800.degree. F. to volatilize the chlorides and burn the combustible volatile material and to produce a refractory material. The flue gases containing the volatilized chlorides are then treated in a condenser where the chlorides are condensed out of the remaining flue gases. The refractory product from the kiln may be passed through a cooler wherein the heat is transferred to the combustion air.

Abstract: A process for removing organic contaminants from a mineral ore such as bauxite. The ore is washed with an aqueous solution containing caustic soda, sodium carbonate or mixtures thereof in an amount up to about 80 g/l total alkali content (expressed as sodium carbonate equivalent). The ore is preferably washed at a temperature of about 95.degree. C. for about 5 hours with a solution containing about 20 g/l total alkali content. In a preferred embodiment, the ore is separated from a rinse solution containing degradation products of organic contaminants, and the washed ore is then dissolved in a caustic solution to produce Bayer process liquor. This process provides a means to reduce the organic carbon concentration in Bayer process liquor, with resultant increase in productivity of the Bayer process.

Abstract: 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).

Abstract: 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.

Abstract: Sodium oxalate impurity is removed from oxalate-enriched Bayer process caustic liquor by gradual increase of the caustic concentration of the liquor, thus providing a staged precipitation of the sodium oxalate in a well-crystallized and readily filterable form.

Abstract: Metal values, such as Co, Ni, Cu and Fe, are recovered from magnet alloy grinding sludge by means of a process comprising: (1) treatment with an organic solvent to remove a major portion of sulfur and oil contaminants, (2) drying, grinding, sizing and magnetic separation to remove a major portion of grinding media contamination, (3) controlled oxidation-roasting to selectively remove residual sulfur and carbon, and (4) gaseous hydrogen reduction to deoxidize metal values.

Abstract: The invention relates to a new method of reducing the organic substance content of alum earth production cycle performed according to the Bayer technology. By the method of the invention the majority of the organic substances present in the circulating lye can be removed easily and with only slight losses in sodium content.According to the invention one proceeds so that soda present in the hydrate wash and/or in the soda salt solution is caustified with lime, the solution is evaporated to reach a total sodium oxide concentration of 200 to 400 g/l, the precipitated solid is separated and removed from the system, and the liquid is recycled.

Abstract: A process for extracting hydrogen fluoride from fluorine containing materials includes countercurrently contacting the materials with steam having a plane of rotation relatively perpendicular to the direction of flow of the material. An apparatus for the extraction of hydrogen fluoride from fluorine containing materials includes a rotary kiln having a first zone wherein a steam-air mixture countercurrently contacts the materials in an oxidation step, a second zone wherein an oxygen containing gas is tangentially injected into the kiln to provide complete combustion of carbon containing materials, a third zone wherein a steam stream countercurrently contacts the materials in a reducing step and means for providing a plane of rotation to the steam which is relatively perpendicular to the direction of flow of the material.

Abstract: Bayer liquor containing carbon compounds is freed from the carbon compounds by a method which comprises adjusting the molar ratio of the aluminum component to the sodium component in the liquid to a value in the range of from 1 to 5 calculated as Al.sub.2 O.sub.3 /Na.sub.2 O and heating the resultant Bayer liquor.

Abstract: Sodium oxalate in supersaturated solution in Bayer spent liquor stabilized by the presence of humic material is precipitated by the treatment with cationic sequestrants which interact with the humic material to give an insoluble product, thus removing it from solution and destabilizing the solution with respect to precipitation of sodium oxalate. Preferred cationic sequestrants are quaternary nitrogen compounds including medium or long chain alkyl groups. Precipitation of sodium oxalate can be expidited by addition of seed crystals and/or addition of sodium oxalate solution which is supersaturated at a temperature higher than that of the spent liquor.

Abstract: Sodium oxalate is supersaturated solution in Bayer spent liquor stabilized by the presence of humic material is precipitated by the treatment with an adsorbent which adsorbs the humic material to give an insoluble product, thus removing it from solution and destabilizing the solution with respect to precipitation of sodium oxalate. The preferred adsorbent is activated carbon. The activated carbon can be dispersed in the spent liquor as a fine powder or the spent liquor can be passed through a column of particulate carbon. Precipitation of sodium oxalate can be expidited by addition to seed crystals and/or addition of sodium oxalate solution which is supersaturated at a temperature higher than that of the spent liquor.

Abstract: Impurities such as organic substances, i.e. sodium oxalate and inorganic impurities, i.e.

Abstract: In the production of alumina from bauxite by the Bayer process, the present invention provides an improvement for effectively and economically removing organic substances from a circulating alkali aluminate solution by contacting the aluminate solution containing organic substances with molecular oxygen gas or a molecular oxygen-containing gas in the presence of copper ions as a catalyst at an elevated temperature, thereby oxidizing the organic substances, adding a chemical substance to the resulting aluminate solution which reacts with copper ions to deposit a water-insoluble precipitate, and separating the precipitate from the solution, and recycling the precipitate as a copper source to the above-mentioned wet oxidation procedure.

Abstract: In the production of alumina from aluminous ores by the Bayer process, the present invention provides an improvement for effectively and economically recovering caustic components consisting essentially of sodium aluminate from aluminum hydroxide cakes as seed classified from the product aluminum hydroxide by washing the seed with a washing liquor having a substantially saturated concentration of sodium oxalate and little content of caustic and then removing organic substances such as sodium oxalate from the washed seed by secondly washing said seed with hot water, thereby recovering caustic components without the dissolution of sodium oxalate from the seed into the recovered caustic solution and attaining the removal of sodium oxalate contaminant with high efficiency.

Abstract: Process for treating solutions from the Bayer process, enabling amounts of sodium carbonate and sodium oxalate or sodium salts of organic acids corresponding to the amounts of these compounds dissolved during the attack on a bauxite to be removed by means of a barium compound, and without consumption of the latter.

Abstract: A method is provided for removing harmful organic compounds from the aluminate liquor obtained in the production of alumina according to the Bayer process. A magnesium obtained is added to the aluminate liquor to form a hydroxide mixture containing magnesium hydroxide and aluminum hydroxide which precipitates from the aluminate liquor. The precipitated mixture is maintained in the aluminate liquor, while being stirred, until at least a part of the organic compounds have been eliminated from the aluminate liquor. The hydroxide mixture containing the organic compounds then is separated from the aluminate liquor.

Abstract: In order to control the sodium oxalate level in the liquor employed in the Bayer process for the production of alumina, a part of the spent liquor recovered from alumina trihydrate precipitation stage is concentrated by evaporation to render it supersaturated with respect to sodium oxalate. The thus concentrated liquor is then sprayed onto a packing in an enclosed space under conditions such that the supersaturation of the droplets at impact on the packing exceeds a critical supersaturation. The sprayed liquor deposits sodium oxalate on the packing and is recovered for recirculation to the process circuit.

Abstract: This invention relates to the disposal of aluminum hydrocarbyl, aluminum hydrocarbyloxy, aluminum halide or aluminum hydride waste materials. Such materials are used as catalysts and may be present alone as well as in combination with similar compounds of other elements typically of Group IV-B, V-B, VI-B, VII-B or VIII. The present disposal process seeks to minimize environmental pollution and provide a product that is suitably used as land-fill. In the process of the invention, a system containing an aluminum hydrocarbon, hydrocarbonoxy, halide or hydride waste stream either with or without a co-present compound of another element as set forth is reacted with a hydroxide or carbonate of a Group I-A, II-A, IV-A, or V-A element under substantially anhydrous conditions. The reaction is comparatively mild and is suitably conducted in ordinary steel equipment without excessive corrosion problems. Diluents co-present with the waste materials are recovered for recycle in anhydrous form without requiring drying.

Abstract: A method for improving the brightness and whiteness of kaolin clays or the like. An aqueous slurry of the clay is initially treated with a solution of sodium borohydride and sodium hydroxide at a pH of above 7.0 up to about 10.0. Sulphur dioxide is then bubbled through the slurry or otherwise brought into contact with same, the pH being permitted to attain a value of between 6.0 and 7.0. The pH may thereupon be adjusted to between 2.5 and 4.0 with an acid, at which pH the leach reaction may occur; or the application of gaseous sulphur dioxide may be continued to yield a pH of the indicated 2.5 to 4.0 range.