Abstract: 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.

Abstract: The invention relates to a process for the reduction of sodium hydroxide losses of the Bayer-cycle by modified causticization of red mud which comprisessubjecting an optionally previously concentrated red mud slurry led off from the red mud washing line by ramification and containing a liquid phase which has a concentration of 5-40 g. caustic Na.sub.2 0/1. caustification by adjusting the lime content expressed as CaO through addition of lime or lime milk to 1-3.2 moles per mole Al.sub.2 O.sub.3, preferably to 2-2.5 moles per mole Al.sub.2 O.sub.3, related to the total Al.sub.2 O.sub.3 content of the slurry;stirring the slurry for 0.3-5 hours at a temperature of 70.degree.-110.degree. C., preferably at 80.degree.-100.degree. C.;adding to the slurry 3-4 moles, preferably 3.2-3.4 moles, of soda related to 1 mole of the originally dissolved Al.sub.2 O.sub.3, and continuing the stirring for 1-4 hours at 80.degree.-100.degree. C., preferably at a temperature of 90.degree.-95.degree. C.

Abstract: During the final stages of Al(OH).sub.3 production, deliquoring the aluminum trihydroxide slurry of excess sodium ions in the form of caustic liquor is conventionally achieved by numerous water washes prior to drying the product. Addition of an effective amount of highly charged, high molecular weight anionic polymer flocculant to the aluminum trihydroxide slurry improves the filtration rate, i.e., increases the amount and rate of removal of caustic liquor from the slurry. Addition of the flocculant reduces the amount of washing necessary to remove sodium ions from the final cake and also provides higher cake solids which results in greater production per unit time and less expenditure of energy in the drying process. Anionic polymers derived from 80 to 100% of an anionic vinyl monomer such as acrylic acid and from 20 to 0% of a nonionic vinyl monomer such as acrylamide having molecular weights between 1.5 to 12.0.times.10.sup.6 are useful in deliquoring aluminum trihydroxide slurries.

Abstract: A process for the production of alumina from aluminum-containing mineral ores, such as bauxite, comprising comminuting the aluminum-containing mineral ore, then reacting the comminuted mineral ore at an elevated temperature with an aqueous solution having at least 150 grams per liter of sodium bicarbonate which forms a solid reaction product containing dawsonite and impurities, and finally converting the dawsonite to alumina.

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: The bayerite form of crystalline alumina, Al(OH).sub.3, contained within a macroporous ion exchange resin is converted to the gibbsite form of Al(OH).sub.3 by reaction with hot MgX.sub.2, where X is halide, followed by water-washing the MgX.sub.2 portion from the product, thereby causing the conversion of bayerite to the gibbsite form of crystalline Al(OH).sub.3. The gibbsite form may then be reacted with hot LiX solution, where X is anion, to form crystalline 2-layer LiX.2Al(OH).sub.3.nH.sub.2 O.

Abstract: Bauxite is reacted with spent caustic soda solution at 113.degree. C. to 205.degree. C. to produce a first pregnant liquor stream, a granular residue stream and a muddy substance stream wherein the granular residue stream is discarded, the muddy substance stream is reacted with or without a small portion of bauxite, but with a spent caustic soda stream at 206.degree. C. to 350.degree. C. to produce a second pregnant liquor stream and a red mud stream which is discarded; the first and second pregnant liquor streams are filtered, cooled to 50.degree. C. to 87.degree. C. and then seeded to precipitate alumina hydrate containing less than 0.017% Fe.sub.2 O.sub.3 by weight.

Abstract: A process for recovering metallic values by putting the values into solution and separating undesired mineral matter from the solution using countercurrent flotation is provided. The process involves leaching metallic values from host rock, conditioning the resultant ore pulp with the required reagents to achieve selective flotation of mineral matter in the metallic values solution, introducing the conditioned ore pulp into flotation cells, along with counterflow of solution from an immediately subsequent flotation step, wherein simultaneous washing and flotation is achieved, and the mineral matter is removed leaving a solution of the metallic values. The resultant mineral matter froth product is subjected to subsequent stages of flotation and simultaneous washing with counterflow of solution removed from each subsequent stage of flotation, water and/or barren solution being used for washing in the final flotation stage.

Abstract: A process is described whereby gadolinium and gallium containing by-products can be reprocessed to yield the oxides of these elements in sufficient purity to be re-used in the process for manufacturing Gd.sub.3 Ga.sub.5 O.sub.12 (GGG) single crystal boules thereby improving the economics of production of GGG wafers significantly. The gadolinium and gallium oxides are recovered and separated from transition metal impurities introduced during fabrication of GGG wafers by precipitating the gadolinium as oxalate which is thereafter pyrolyzed to gadolinium oxide and eluting the gallium containing filtrate over an ion exchange resin and precipitating therefrom as an oxalate the gallium present. The gallium precipitate is also pyrolyzed to the gallium oxide. The process can be extended to include purification and re-use of by-products generated in other grinding and polishing operations which may result in the recycling of the order of 80% of the generated by-products.

Abstract: Bayer process caustic liquors are purified by treating the liquors with an organic solvent of relatively low boiling point, such as methanol, which causes the precipitation of inorganic carbonate and/or sulfate salt from the treated liquor. The treating solvent can be readily recovered for reuse.

Abstract: A process for removing sulfur dioxide from effluent gas and for recovering amphoteric components such as alumina from solid inorganic combustion byproducts.

Abstract: A process is described whereby the "saw kerf" can be reprocessed in sufficient purity to be re-used in the process, thereby improving the economics of production of GGG wafers significantly. Gadolinium and gallium oxides are recovered and separated from transition metal impurities introduced during fabrication of GGG wafers. The process "saw kerf" produced from slicing the crystal boule is dissolved by refluxing in HNO.sub.3, treated with oxalic acid and the resulting oxalates and nitrates separated. Pyrolysis of these salts at temperatures of at least 850.degree. C. resulted in their conversion to Ga.sub.2 O.sub.3 of purity >99.99%. The process can be extended to include purification and re-use of by-products generated in other grinding and polishing operations which may result in the recycling of the order of 80% of the generated by-products.

Abstract: A process is described whereby the by-products derived from the fabrication of Gd.sub.3 Ga.sub.5 O.sub.12 (GGG) wafers sliced from boules grown from Gd.sub.2 O.sub.3 and Ga.sub.2 O.sub.3 can be reprocessed in sufficient purity to be re-used in the process of growing GGG boules, thereby improving the economics of GGG wafer production. Gadolinium and gallium oxides are recovered and separated from transition metal impurities introduced during fabrication of GGG wafers. The "saw kerf" produced from slicing the crystal boule is dissolved in HCl and filtered to remove residual solids. Gasolinium oxalate is precipitated from the acidic solution by the addition of oxalic acid. Calcination at 850.degree. C. resulted in the isolation of Gd.sub.2 O.sub.3 of >99.99 purity.The pH of the filtrate is adjusted to about 11 with alkali metal hydroxide followed by the addition of sulfide ion. The precipitated transition metal sulfides are removed by filtration. Excess sulfide is removed by treatment with 30% H.sub.2 O.sub.

Abstract: An aqueous slurry of a water-insoluble or slightly water-soluble metal hydroxide can be effectively filtrated and dehydrated by adding an anionic surfactant of the following formula (I):R--O--AO--.sub.n X (I)wherein R represents an alkyl or alkenyl group of 8-24 carbon atoms, A represents an alkyene group of 2-4 carbon atoms, X represents SO.sub.3 M (M being H, K, Na or NH.sub.4), PO.sub.3 M (M being K or Na) or CH.sub.2 COOM (M being K or Na), and n represents an interger of 1-100,to the aqueous slurry of the metal hydroxide or to the washing water.

Abstract: Coarse grains of aluminum hydroxide having high resistance to disintegration to powder in a calcination step are continuously produced from a supersaturated sodium aluminate solution of the Bayer process through(1) a first precipitation step of adding recycle seed aluminum hydroxide to a supersaturated sodium aluminate solution having a molar ratio of Na.sub.2 O as caustic soda to Al.sub.2 O.sub.3 in solution of less than 1.8 supplied to a precipitation tank of substantially complete mixing type in a ratio of 30-150 kg of the recycle seed to 1 m.sup.3 of the solution, thereby partially decomposing the seed-added solution until the molar ratio of the solution reaches 2.0-2.4 while keeping the solution at 65.degree.-80.degree. C.

Abstract: Chromium and vanadium can be co-extracted from alkaline solutions or leach liquors containing these metals using quaternary amine solvent mixtures. The alkaline leach liquors usually are derived by leaching of calcined ores or concentrates. The loaded solvent mixture is scrubbed with chromium solution to remove all metals except chromium, and the chromium is then recovered from the solvent phase. The vanadium can be recovered from the scrub liquor. Recovery of aluminum is also possible.

Abstract: Disclosed is a method for obtaining alumina from silicates by calcining a dry mixture of the silicate and an alkali metal or ammonium salt, such as the sulphate, bisulphate, sulphite, etc. and dissolving the reaction product in water or an aqueous alkali. Hydrated alumina is precipitated from the resulting solution and calcined to alumina.

Abstract: In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles primarily in the form of water-soluble alkali metal sulphites and bisulphites by treating the particles with a solution of sulfurous acid. During the treating process the water-insoluble alkali metal compounds in the alkali metal residues are converted into water-soluble alkali metal sulphites and bisulphites, which have been found to be catalytically active.

Abstract: A wet caustic aluminate process that comprises digesting a bauxite at a low temperature in caustic aluminate liquor to extract the alumina trihydrate, separating the supersaturated caustic aluminate liquor of low Fe.sub.2 O.sub.3 content from the mud, digesting the mud or a mixture of mud and bauxite at a higher temperature in caustic aluminate liquor to extract the majority of the remaining monohydrate and trihydrate, separating the supersaturated caustic aluminate liquor of higher Fe.sub.2 O.sub.3 content from the residue, precipitating alumina hydrate from the two supersaturated caustic aluminate liquors, recyling spent caustic aluminate liquor to digestion and calcining alumina hydrate to alumina with a Fe.sub.2 O.sub.3 content less than 0.03%.

Abstract: Coarse grains of aluminum hydroxide are economically produced in a high yield from sodium aluminate solution by dividing supersaturated sodium aluminate solution being prepared by the Bayer process and having a molar ratio of Na.sub.2 O as caustic soda to Al.sub.2 O.sub.3 in solution of less than 1.8 into two streams, adding a portion of recycle seed aluminum hydroxide and fine grains of aluminum hydroxide as seed to one of the streams of sodium aluminate solution, partially decomposing the sodium aluminate solution until the molar ratio of the sodium solution reaches 1.8-2.6, adding to the resulting partially decomposed sodium aluminate slurry the other stream of sodium aluminate solution, which has been cooled to a temperature low enough to lower the temperature of the partially decomposed sodium aluminate slurry by at least 3.degree. C.

Abstract: A precipitation system is provided for the production of strong, coarse alumina hydrate (Al.sub.2 O.sub.3.3H.sub.2 O) from Bayer process aluminate liquors. In the system three distinct, but interconnected processing stages are utilized which comprise an agglomeration stage, a growth stage and a seed generation stage. In the agglomeration stage hydrate particles agglomerate to form coarse particles; in the growth stage these particles grow and acquire strength; while in the seed generation stage alumina hydrate seed is generated to be used in the agglomeration and growth stages.The precipitation system combines the advantages of both the American and European Bayer processes in that it results in the production of a strong, coarse product hydrate and an increased yield.

Abstract: Disclosed is a process for refining a magnesium and nickel containing ore, comprising the steps of grinding the ore; preparing a slurry of the ground ore in sulfuric acid containing less than ten percent of water; adding water to the acid-ore slurry in an amount which is effective to initiate a sulfation reaction; allowing the sulfation reaction to continue, utilizing the heat of the sulfation reaction to heat the acid-ore slurry, whereby water-soluble metal sulfates and insoluble residue are formed; leaching the sulfation product with water to extract the water-soluble metal sulfates in solution; separating the metal sulfates solution from the insoluble residue; precipitating from the solution metals other than Mg as hydroxides; separating the solution from the metal hydroxide precipitate; concentrating the solution sufficiently to precipitate CaSO.sub.4 ; separating the concentrated solution from the precipitate; recovering dehydrated MgSO.sub.

Abstract: The production process for pseudoboehmite from leach liquors produced in the acid treatment of clays, which liquors contain Fe and alkaline earth ions.

Abstract: A process for the removal of iron and aluminum values from acidic solutions thereof with zinc chloride wherein the solution is subjected to pressure hydrolysis to precipitate the iron and aluminum as the hydroxides or oxide hydrates, and then the precipitate is removed and washed. Zinc chlorides which are particularly free from iron and aluminum can be rapidly and easily obtained with this process.

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: A process and installation for the integrated treatment of concentrated residual solutions resulting from the anodization of aluminium parts is described, in which caustic soda is employed in the pickling process and sulphuric acid in the anodization bath.The process comprises three sets of operations:(1) Production of aluminium sulphate in concentrated solution or in hydrated crystals, by the treatment of part of the residual solution from the anodization.(2) Production of precipitated aluminium hydroxide and a solution of sodium sulphate from residual anodization and pickling solutions.(3) Production of sodium aluminate from residual pickling solutions and aluminium hydroxide producted in (2). (FIG. 1.

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

Abstract: Aluminum nitrate solutions are subjected to hydrolysis at elevated temperature and pressure, with the pressure being kept relatively low by continual bleeding of reactant gases from the reaction vessel. The resultant product is a noncrystalline alumina that may be readily converted to crystalline alumina by roasting.In addition, the discharged reactant gases are employed for leaching of clay to provide aluminum nitrate feed solution.

Abstract: An improved method for recovering aluminum values from alkaline aluminosilicate raw material by sintering a comminuted aqueous mixture of the alkaline aluminosilicate material, limestone and soda solution wherein the alumino-silicate material is first comminuted with the soda solution to form a mixture with a fraction of particles larger than 0.08 mm greater than 20 percent by weight, mixing limestone with the mixture and comminuting until the fraction of particles larger than 0.08 mm is between 2 and 15 percent by weight.

Abstract: Process for the manufacture of coarse aluminum hydroxide, containing a maximum of 15 weight percent of the particles in a particle size under 45 micrometers, with a productivity that may be higher than 60 grams of precipitated Al.sub.2 O.sub.3.The process consists of a decomposition in two stages (an agglomeration phase and a growth phase); each stage proceeding within defined temperature ranges with seed material of different constitution. The first (fine) seed amount is added at the start of the decomposition in such an amount, that the ratio of the supersaturation of the aluminate liquor to the surface area of the seed hydroxide per liter of the aluminate liquor presented for decomposition exhibits a value of 7 to 25 grams per square meter. The process exhibits the advantage of the high productivity of the so-called European process and the advantage of the so-called American process by obtaining a coarse product hydroxide.

Abstract: Method for the recovery of high purity Cr.sub.2 O.sub.3 from a Na.sub.2 CrO.sub.4 or Na.sub.2 Cr.sub.2 O.sub.7 solution by producing (NH.sub.4).sub.2 CrO.sub.4 by solvent extraction, evaporating the aqueous (NH.sub.4).sub.2 CrO.sub.4 and igniting the resulting solids to provide high purity Cr.sub.2 O.sub.3.

Abstract: An improvement in processes for recovering aluminum from alunite ore which processes include roasting the ore to remove water of hydration, removing sulfur and potassium compounds from the roasted ore by a procedure including a first leaching step resulting in a residue and a solution containing potassium sulfate, effecting partial recovery of potassium sulfate from the solution by crystallization with some potassium sulfate being bled off from the mother liquor, converting aluminum values in the residue to alkali metal aluminates by digesting the residue with alkali metal hydroxide including a substantial amount of sodium hydroxide, removing silicon from the alkali metal aluminates leaving a waste desilication product, recovering aluminum values from the desilicated aluminates by precipitation, circulating the mother liquor from the precipitation step to digestion as contaminated sodium hydroxide is bled off, the improvement which comprises enhancing the economics of the overall process by introducing therei

Abstract: In a process for the production of alumina which comprises the steps of digesting bauxite to produce a precipitate of alumina trihydrate containing uncombined moisture, drying the alumina trihydrate to reduce the uncombined moisture content thereof, and feeding the dried alumina trihydrate to a calciner to convert the alumina trihydrate to alumina, improved economy is achieved by drying the alumina trihydrate in a fluidized bed in which the fluidized mass is heated indirectly by means of steam which is available from the digestion and recovery system. Drying of the alumina trihydrate in this manner prior to feeding it to the calciner also reduces the fuel requirement in the calciner and enables the throughput of the calciner to be increased.

Abstract: Method for the recovery of chrome hydrate or high purity Cr.sub.2 O.sub.3 from chromium ores by roasting the ore with Na.sub.2 CO.sub.3 and CaO, water leaching the roasted mass, precipitating aluminum impurities from the leach liquor as Al(OH).sub.3 and contacting the leach liquor with sulfur and NaOH in order to reduce the chromium values in the leach liquor from valence 6 to 3 to provide a chrome hydrate precipitate. The chrome hydrate precipitate is acid repulped to provide a chrome hydrate from which sodium impurities have been removed. The chrome hydrate is dried and the resulting solids are calcined to provide a high purity Cr.sub.2 O.sub.3.

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: A method for treating nonferrous metal hydroxide sludge waste to separate and recover the nonferrous metals therein wherein the waste is first mixed with an alkali hydroxide or carbonate, dried, and then roasted and the water-insoluble residue in the roasted material is treated with sulfuric acid to produce an acid-insoluble residue and a sulfuric acid solution containing copper, aluminum and chromium and thereafter, separating the copper from this solution by liquid-liquid extraction and thereafter, separating the aluminium, chromium, zinc and nickel from the remaining solution by separate liquid-liquid extraction steps.

Abstract: In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water. The treating process is carried out under conditions such that the calcium or magnesium-containing compound reacts with water insoluble constituents of the alkali metal residues such as alkali metal aluminosilicates to produce an aqueous solution containing water soluble alkali metal constituents. The aqueous solution is recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

Abstract: Metals are recovered from waste materials that contain an organic component and a bimetallic salt complex component that comprises complexes having the formula M.sub.I M.sub.II X.sub.n.Aromatic and/or the formula M.sub.I M.sub.II X.sub.n.M.sub.II OX.Aromatic, wherein M.sub.I is a Group I-B metal, M.sub.II is a Group III-A metal, X is halogen, n is the sum of the valences of M.sub.I and M.sub.II, and Aromatic is a monocyclic aromatic hydrocarbon or halogenated aromatic hydrocarbon having 6 to 12 carbon atoms, by hydrolyzing the waste material with dilute hydrochloric acid to form a hydrolysis mixture that separates into an organic phase and an aqueous phase, and, after removing the organic phase, adding to the aqueous phase sufficient aluminum or another reducing metal to precipitate the Group I-B metal. After the precipitated metal has been removed from it, the aqueous solution is treated with sufficient base to precipitate the Group III-A metal hydroxyide, which is recovered from the aqueous solution.

Abstract: Metals are removed from waste materials that contain an organic component and a bimetallic salt complex component that comprises complexes having the formula M.sub.I M.sub.II X.sub.n .multidot.Aromatic and/or the formula M.sub.I M.sub.II X.sub.n .multidot.M.sub.II OX.multidot.Aromatic, wherein M.sub.I is a Group I-B metal, M.sub.II is a Group III-A metal, X is halogen, n is the sum of the valences of M.sub.I and M.sub.II, and Aromatic is a monocyclic aromatic hydrocarbon or halogenated aromatic hydrocarbon having 6 to 12 carbon atoms by contacting the waste material with water and sufficient alkali metal hydroxide to form a hydrolysis mixture which has a pH above 5 and which separates into an upper organic phase and a lower aqueous phase. After separation of the phases, there is obtained a slurry of M.sub.I oxide, M.sub.I hydroxide, and/or M.sub.II hydroxide from which the metals can be recovered or which can be discarded in ways that are not damaging to the environment.

Abstract: A method for recovering nonferrous metal values from hydroxide sludge wastes containing same by first chlorinating the aqueous waste to oxidize the chromium therein, separating the insoluble components therefrom and treating the resulting Cr(VI) solution in a fixed bed anion exchanger to separate the Cr(VI) from the solution, separating the copper from the aqueous solution by liquid-liquid extraction, separating the zinc from the copper-free solution by liquid-liquid extraction, precipitating and separating the aluminum in the form of hydroxide from the zinc-free solution and then separating the nickel from the aluminum-free solution by liquid-liquid extraction, and recovering the nonferrous metals from the respective solutions and precipitates by conventional procedures.

Abstract: From roasted products of used catalysts from hydrotreatment desulfurization of petroleum, valuable molybdenum, vanadium, cobalt and nickel are recovered easily and a high percent recovery by means of a combination of simple chemical procedures and also inexpensive chemicals. The recovered metal components can be reused for preparing new catalysts and the like.

Abstract: A process for recovering mineral values from fly ash in commercial quantities comprising forming an alkaline aqueous fly ash blend, filtering the alkaline aqueous fly ash blend and recovering a solids blend therefrom, leaching the solids blend with hydrochloric or hydrofluoric acid to form dissolved chloride or fluoride salts of iron, aluminum and other metals, electrolyzing the dissolved chloride or fluoride salt solution to plate out at least iron, and, optionally, one or more other metals, recovering silicon dioxide as a precipitate from the leaching solution, and recovering the leaching solution free of silicon dioxide. Neutralizing the leaching solution in a certain pH range permits precipitation and recovery of aluminum hydroxide as a solid. The hydroxide may then be converted to alum or alumina by conventional methods.

Abstract: A process for alunite ore treatment which comprises roasting alunite in the presence of oxygen at a temperature of from 580.degree. to 620.degree. C. for 1 to 3 hours, decomposing the roasted alunite by exposure to reducing agents at a temperature of from 580.degree. to 620.degree. C., subjecting the reduced alunite to hydrochemical treatment by use of a sodium hydroxide solution of concentration from 100 to 150 g/lit in terms of Na.sub.2 O, decomposing the resultant aluminate liquor, with the aluminum hydroxide component precipitating out, and finally, washing and baking the aluminum hydroxide precipitate to obtain same as an end product. The invention provides a comprehensive method of treatment of alunite ores the associated rock whereof comprises silica in the form of opal and chalcedony earlier believed to be refractory to comprehensive treatment by alkaline methods.

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: Alumina monohydrate is produced by leaching calcined clay and subjecting the leach liquor to pressure hydrolysis wherein the vapor and heat resulting from the pressure hydrolysis are directly utilized for leaching of the calcined clay. The aluminum monohydrate may be roasted to yield alumina.

Abstract: The invention is an improvement in the method for recovering aluminum values from alunite ore by roasting the ore to remove water, reducing the ore by roasting it in a reducing atmosphere to remove sulfate, optionally roasting the reduced ore in an oxidizing atmosphere to convert any sulfides formed in the second roast to oxides, leaching the calcined ore with water as a solvent to remove compounds of sulfur and alkali metals, recovering aluminum values as soluble aluminates from the residue from the leaching step by digesting it with at least one alkali metal hydroxide, removing contaminate silica from the resulting leach solution, and precipitating aluminum hydroxide from the solution, the improvement being the use of a two stage reduction of the dehydrated alunite ore, in which the ore is reduced by sulfur in the first stage, followed by a second stage reduction with another reducing agent such as hydrogen.

Abstract: Aluminum chlorohydroxide represented by the formula Al.sub.2 (OH).sub.x Cl.sub.y in which x and y range from 1 to 4 and 5 to 2, respectively, is produced by reacting hydrochloric acid with an amount of aluminum oxide or hydroxide which is equal to or slightly greater than the stoichiometric amount for obtaining aluminum trichloride, in the temperature range of from 160.degree. to 270.degree. C, and in the pressure range of from 0.1 to 50 kg/cm.sup.2.

Abstract: An improvement in the process for the recovery of aluminum from alunite in which potassium hydroxide is recovered from byproduct potassium sulfate by electrodialysis, further improvement being the use of sodium hydroxide from the bleed stream from the Bayer leach for use in the electrodialysis process for recovering potassium hydroxide from potassium sulfate.

Abstract: Gallium and other values are recovered from phosphorus-furnace flue-dust by treating dust with sulfuric acid to form a solution and a residue. The residue may be treated for recovery of values. Zinc is precipitated from the solution as zinc ammonium sulfate hexahydrate and an alkaline material is added to precipitate a gallium concentrate and to form a gallium-free solution, which may be treated for recovery of sulfate and phosphate values. The gallium concentrate may be upgraded by mixing concentrate with lime to precipitate calcium phosphate and by subsequently adding sodium hydroxide to redissolve coprecipitated gallium and aluminum compounds. Residual precipitate is recycled and the solution is neutralized to precipitate an upgraded concentrate. Aluminum may be removed as calcium aluminate. Upgraded concentrate may be dissolved in alkaline solution and the solution electrolyzed for deposition and recovery of gallium.