Abstract: A method comprises reacting an aluminum feedstock with an acid in the presence of water to provide an aluminum salt solution comprising an aluminum salt in water, wherein the aluminum salt comprises a reaction product of the acid and aluminum, and spray roasting the aluminum salt solution at a temperature of at least about 450° C. to provide an aluminum oxide powder, wherein the spray roasting is performed in a furnace lined with a refractory comprising alumina that is at least about 99.2% purity alumina, and wherein the aluminum oxide powder is 99.2% pure aluminum oxide or greater.

Abstract: The present invention discloses methods for leaching beryllium from a beryllium-containing concentrate or a beryllium-containing ore, comprising contacting the concentrate or the ore with a leaching solution, wherein the leaching solution contains a technical grade hydrochloric acid, wherein the solution contains no sulfuric acid, no nitric acid, and no potassium chlorate, extracting beryllium via a gradual heating process, wherein the technical grade hydrochloric acid is used in varying amounts by volume per liter of leaching solution, and adding ammonium fluoride to the leaching solution in contact with the concentrate or ore, wherein the ammonium fluoride is added in a fractional manner.

Abstract: The invention relates to acid methods for producing alumina for use in processing low-grade aluminum-containing raw materials. The method provides treating aluminum-containing raw materials with hydrochloric acid, crystallizing aluminum chloride hexahydrate by evaporating the supernatant chloride solution, and thermally decomposing the aluminum chloride hexahydrate to form aluminum. Crystallization is carried out with the addition of calcium chloride.

Abstract: There are provided processes for preparing various products from various materials. For example, such processes are effective for extracting titanium and various other metals from various materials, thereby allowing for preparing products such as titanium chloride and titanium oxide. These processes can comprise leaching the starting material with HCl so as to obtain a leachate and a solid. The solid can be treated so as to substantially selectively extract titanium therefrom while the leachate can be treated so as to substantially selectively recover a first metal chloride therefrom.

Abstract: There are provided processes for treating fly ash. For example, the processes can comprise leaching fly ash with HCl so as to obtain a leachate comprising aluminum ions and a solid, and separating the solid from the leachate; reacting the leachate with HCl so as to obtain a liquid and a precipitate comprising the aluminum ions in the form of AlCl3, and separating the precipitate from the liquid; and heating the precipitate under conditions effective for converting AlCl3 into Al2O3 and optionally recovering gaseous HCl so-produced.

Abstract: There are provided processes for preparing alumina. These processes can comprise leaching an aluminum-containing material with HCl so as to obtain a leachate comprising aluminum ions and a solid, and separating said solid from said leachate; reacting said leachate with HCl so as to obtain a liquid and a precipitate comprising said aluminum ions in the form of AlCl3, and separating said precipitate from said liquid; and heating said precipitate under conditions effective for converting AlCl3 into Al2O3 and optionally recovering gaseous HCl so-produced. These processes can also be used for preparing various other products such as hematite, MgO, silica and oxides of various metals, sulphates and chlorides of various metals, as well as rare earth elements, rare metals and aluminum.

Abstract: The present invention relates to methods for recovering precious metals including silver and gold, rare metals including indium and gallium, base metals including copper, lead and zinc or a combination of precious, rare and base metals from complex oxide ores, sulfide ores or oxide and sulphide ores using an acid chloride oxidizing leach.

Abstract: There are provided processes for extracting aluminum ions from aluminous ores and for preparing alumina. Such processes can be used with various types of aluminous ores such as aluminous ores comprising various types of metals such as Fe, K, Mg, Na, Ca, Mn, Ba, Zn, Li, Sr, V, Ni, Cr, Pb, Cu, Co, Sb, As, B, Sn, Be, Mo, or mixtures thereof.

Abstract: As population density increases, the transportation of hazardous chemicals, including acids and disinfectants, lead to an increased incidence of spills while the consequences of spills become more serious. While solutions of halide acids, hypohalites and halites are safer disinfectants for transportation, handling, storage and use than traditional gaseous chlorine, the manufacturing cost of these disinfectants has here-to-fore limited their use. Economical processes are presented for the manufacture of O2, halogen oxides, halide acids, hypohalites, and halates; as well as polynucleate metal compounds, metal hydroxides and calcium sulfate hydrate (gypsum). The instant invention presents methods and processes that incorporate the use of sulfur. This is while environmental regulators, such as the US EPA, require an increased removal of sulfur from hydrocarbon fuels, thereby creating an abundance of sulfur, such that the refining industry is in need of a way to dispose of said abundance of sulfur.

Abstract: A method for preparation of iodizing agent for the use in the formulation of iodized salt that offers excellent stability of iodine in iodized salt is developed and the unrefined salt iodized with this compound was tested for its stability in presence of moisture, temperature and metal salts at higher temperature. The hydrotalcite type layered compound was used to prepare such compound and part of carbonate was substituted with iodate anion. The iodizing agent exhibited excellent stability of iodine in iodized salt.

Abstract: The present invention provides a recovery method in which the indium sponge that is deposited by substitution in the substitution deposition step in the recovery of indium from an indium-containing material is produced in the form of a powder rather than in a bulky form. This recovery method is a method in which an indium sponge is deposited by substitution by adding a substance containing chlorine, and further adding a reducing agent, to an indium-containing solution whose pH has been adjusted to a value in the range of 1 to 2.2.

Abstract: A method of recovering AlF3 from spent potliner using an acid digest to form gaseous HF which is converted to hydrofluoric acid and reacted with alumina trihydrate to form AlF3.

Abstract: A process of treating spent potliner material from aluminum reduction cells and recovering useful products. In the process of the present invention, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. As a result of this step, a gas component is produced which includes hydrogen fluoride, silicon tetrafluoride and hydrogen cyanide. Also, a slurry component is produced which includes carbon, a refractory material including silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the silicon tetrafluoride to fumed silica, hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas.

Abstract: A process for the simultaneous recovery of substantially pure alumina and silica from an aluminosilicate. The process comprises the following steps: (i) heating the aluminosilicate with hydrated CaCl.sub.2 to obtain calcium-alumino-silicate and calcium-aluminate products, wherein the CaCl.sub.2 is substantially free of MgCl.sub.2 ; (ii) leaching the products with HCl to form a solution comprising AlCl.sub.3 and CaCl.sub.2, and insoluble silica; (iii) separating the insoluble silica from the solution; and (iv) crystallizing AlCl.sub.3 from the solution and recovering the alumina from the crystallized AlCl.sub.3. The process may further comprise the following steps: (v) substantially removing MgCl.sub.2 from the CaCl.sub.2 solution of step (iv); and (vi) recycling the CaCl.sub.2 solution for use in step (i).

Abstract: A process for treating spent potliner material from aluminum reduction cells and recovering useful products. In the process, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. A gas component is produced which includes hydrogen fluoride and hydrogen cyanide. A slurry component is produced which includes carbon, silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas. The remaining gas component is directed through a water scrubber in which the HF gas is converted to liquid hydrofluoric acid.

Abstract: A process for removing dissolved fluorides from an aqueous stream using at least two reactors wherein the dissolved fluoride containing aqueous feed and an unreacted aluminum containing sludge are combined in the first reactor to give a first reactor admixture after which the first reactor effluent stream is directed to the second reactor and therein combined with fresh alum and fresh sodium aluminate to give a second reactor admixture comprising a reduced fluoride aqueous solution and a partially reacted aluminum containing sludge and thereafter recovering the reduced fluoride aqueous solution and recycling at least a portion of the aluminum containing sludge to the first reactor.

Abstract: The present invention relates to a method for recovering iron chloride, aluminum chloride and calcium chloride from silicon and ferrosilicon or from residues which contain silicon and/or ferrosilicon and metal chlorides and optionally copper and/or copper compounds, which materials are leached with HCl or HCl+FeCl.sub.3 /FeCl.sub.2 solutions, whereafter the solid silicon or ferrosilicon residue is removed from the leach solution and where any copper is removed from the leach solution. Fe.sup.2+ in the leach solution is oxidized to Fe.sup.3+ whereafter the leach solution is subjected to a liquid-liquid extraction by means of an organic phase containing n-tributyl phosphate dissolved in a hydrocarbon solvent in order to extract FeCl.sub.3 and at least a part of CaCl.sub.2 from the leach solution, stripping FeCl.sub.3 and any CaCl.sub.2 from the organic phase by water, concentrating the remaining solution by evaporation and adding HCl gas to the solution in order to selectively precipitate AlCl.sub.3.6H.sub.

Abstract: A method for producing an anion intercalated hydrotalcite without first forming hydrotalcite and then having to activate the hydrotalcite prior to substituting anions in the hydrotalcite structure. The method includes reacting an activated magnesia with an aqueous solution of aluminate, anion, such as bromide, chloride, sulfate, borate and combinations thereof and hydroxyl ions. The method can be carried out at atmospheric pressure to form hydrotalcite in high purity and high yield. In a preferred embodiment of the invention, the aluminate solution is formed from sodium aluminate, sodium bromide and sodium hydroxide and the aqueous solution is substantially carbonate free. Other anion intercalated hydrotalcites can also be produced by the method of the present invention.

Abstract: Process for the recovery of aluminum and fluoride values from spent pot lining materials comprising the steps of calcining spent pot lining material to produce an ash having environmentally acceptable levels of cyanide contamination, subjecting the ash to a leaching step in a solution containing a mineral acid and a corresponding aluminum salt in such proportions as to dissolve the aluminum and fluoride values, and subjecting the leached liquid to thermal hydrolysis to cause precipitation of an aluminum fluoride product.

Abstract: A method for recovering gallium, which comprises a capturing step of contacting an aqueous solution containing gallium to a chelating agent containing a water-insoluble substituted quinolinol as the active ingredient, to let the chelating agent capture gallium, and an eluting step of contacting an eluting solution composed of an aqueous solution of an acid or strong base containing said substituted quinolinol, to the chelating agent from the capturing step, to elute gallium therefrom.

Abstract: Disclosed is a process for recovering gallium values contained in a basic aqueous solution by liquid/liquid extraction thereof. The liquid/liquid extraction process comprises contacting the basic aqueous solution with a water-immiscible, organic phase comprising a substituted hydroxyquinoline dissolved in an organic solvent therefor whereby gallium is extracted into the organic phase. Thereafter, the organic phase is separated from the basic aqueous phase and the gallium recovered from the separated organic phase. The improvement in process of the present invention comprises the organic phase further comprising dissolved therein an organic dioxime compound.

Abstract: Fluoride-containing wastes, arising in the aluminium industry, particularly spent cell linings from reduction cells, are digested with caustic soda for conversion of sodium cryolite to NaF.By use of very strong caustic soda NaF may be left in the solid residues after removal of the residual liquor and recovered from such residues by water leaching.As an alternative weaker caustic soda may be used in the digestion stage and subsequently be crystallised out from the residual liquor, after separation from the solid residues, by evaporating and/or cooling the liquor. The precipitated NaF is then conventiently redissolved in water.The NaF solution prepared by either route is then preferably subjected to electrodialysis to recover a solution of HF from it. Such HF is conveniently converted to AlF.sub.3 by reaction with alumina.

Abstract: Scrap containing gallium and arsenic is treated with chlorine gas to form a crude gallium and arsenic chloride mixture. Arsenic chloride and impurities having a lower boiling point than that of arsenic chloride are removed from the mixture by vaporization so that crude gallium chloride may be obtained. The crude gallium chloride is purified by distillation. The purified gallium chloride is electrolyzed to yield metallic gallium. If the scrap has a molar gallium/arsenic ratio exceeding 1, arsenic chloride or metallic arsenic or both are added to the scrap before it if treated with chlorine gas.

Abstract: The method of the present invention is a novel comprehensive process for maximizing the recovery of valuable mineral values from coal ash. Options may also be included for the production of saleable inorganic chemical by-products. The process employs both physical and chemical extraction techniques that maximize the yield of products while reducing the quantity of waste produced. Valuable minerals and chemicals such as cenospheres (hollow microspheres), carbon, magnetite (Fe.sub.3 O.sub.4), alumina (Al.sub.2 O.sub.3), iron oxide (Fe.sub.2 O.sub.3) and iron chloride (FeCl.sub.3) may be produced. Due to removal of carbon, magnetite, and iron oxide from the coal ash, the processed ash comprises a quality pozzolan.

Abstract: A process is described for the formation of high purity alumina from Bayer Process alumina trihydrate (gibbsite). The solid hydrated alumina is reacted with concentrated HCl to cause partial or complete conversion to aluminum chloride hexahydrate (ACH). The ACH or mixture of ACH and unreacted hydrated alumina is recovered as a solid and calcined in a single or multistage calcination to high purity alumina. Soda contents in the product anhydrous alumina can be reduced by 98% or greater. Contents of other impurities, such as silica, iron, magnesium, etc., are also markedly reduced. Different degrees of impurity reduction can be obtained by controlling the degree of conversion of the hydrated alumina to ACH and by recycling and treating the acid after solid/liquid separation. The purified products find use in the specialty ceramics field, as catalyst supports, as adsorbents, in electronic components, in prosthetic devices or other applications in which alumina of controlled degrees of purity offers an advantage.

Abstract: A process is provided for hydrometallurgical processing of steel plant dusts containing cadmium, lead, zinc, and iron values, along with impurities such as chloride and fluoride salts of sodium, potassium, magnesium, etc. The first step in the process involves leaching the dust in a mixed sulfate-chloride medium that dissolves most of the zinc and cadmium. Any iron and aluminum dissolved in this step is precipitated by oxidation and neutralization. Zinc is recovered from the resulting solution by solvent extraction which provides a raffinate which is recycled to the leaching step with a bleed stream also provided for recovery of cadmium and removal of other impurities from the circuit. The lead sulfate residue from the leaching step is leached with caustic soda, and zinc dust is used to cement the lead out from the caustic solution, which then joins the main solution for zinc recovery.

Abstract: A process is described for the formation of high purity alumina from aluminas such as Bayer Process alumina trihydrate (gibbsite) which contain both acid-soluble and -insoluble impurities, notably soda and silica. The solid hydrated alumina is reacted with a stoichiometric quantity of concentrated HCl to form a reaction product comprising of dissolved aluminum chloride and solid aluminum chloride hexahydrate (ACH). The acid and/or aluminum chloride concentration of the solution is then adjusted (as by water addition) to dissolve the solid ACH and form a solution at or near saturation in aluminum chloride, but with the remaining solid materials undissolved. The solution is then subjected to solid/liquid separation to eliminate the insoluble impurities, such as silica.

Abstract: The invention relates to a method for recovering useable products from waste products deriving from the manufacture of aluminium fluoride on the basis of aluminium hydroxide and fluosilicic acid. Mother liquors and washing water from a scrubber in said process, which solutions contain aluminium, silica, fluorine, and phosphorous is reacted in a first step with sodium ions at pH 2-3, and a temperature of 50.degree.-100.degree. C. to give a precipitate of sodium fluoroaluminate, which is isolated. The filtrate from said first step can be reacted with the silica waste product obtained in the above mentioned aluminium fluoride manufacture.

Abstract: A process is described for the direct chlorination of hydrated alumina (preferably alumina trihydrate) to aluminum chloride hexahydrate (ACH) by reaction with concentrated hydrochloric acid. Preferably all of the initial hydrated alumina is converted to ACH. The ACH partially calcined to form an amorphous mixture of aluminum oxides and oxychlorides. This mixture is then reductively chlorinated to form anhydrous aluminum chloride which is suitable as a source of electrolytically produced aluminum metal.

Abstract: A leaching process employing acidic chloride solutions, whereby the iron content of aluminous materials such as lower grade iron-containing bauxite ores is reduced, enabling the obtention of valuable products such as metallurgical grade alumina and refractory grade bauxite, previously obtainable only from higher grade low-iron aluminous materials.

Abstract: A starting solid mixture of AlCl.sub.3 and Nacl, which may have been obtained by acid leaching of an aluminiferous mineral and precipitation of the AlCl.sub.3 and NaCl, is mixed with water in an amount to form an aqueous solution containing NaCl and AlCl.sub.3 in a weight ratio Na.sub.2 O/Al.sub.2 O.sub.3 of about 0.028. This is sparged with HCl to precipitate AlCl.sub.3, but the sparging is stopped before a substantial concentration of NaCl starts to come out of solution. The precipitated AlCl.sub.3 may be calcined to Al.sub.2 O.sub.3 and washed to remove any residual NaCl.

Abstract: An improved method of producing anhydrous aluminum chloride via aluminum chloride hexahydrate is provided. In a preferred embodiment the method is incorporated into a process for producing aluminum from aluminous ores, and particularly from domestic ore sources comprising (1) acid leaching an aluminous ore to produce aluminum chloride hexahydrate (ACH); (2) calcining the ACH to a specific temperature of above about 450.degree. C. to produce highly reactive aluminous particles containing high residual chloride and low residual hydrogen levels; (3) reductively chlorinating the calcined ACH at a low temperature to produce anhydrous aluminum chloride suitable for electrolytic reduction; and (4) electrolytically reducing the anhydrous aluminum chloride in a fused salt to produce aluminum metal and chlorine which is recycled to step (3).

Abstract: An improved process is provided for producing via ACH anhydrous aluminum chloride suitable for electrolytic reduction to aluminum wherein the feed ACH is acid leach derived. In a preferred embodiment the acid leach derived ACH is single stage crystallized.

Abstract: A process for separating inorganic substances involving their abstraction from a mixture with near-supercritical inorganic fluids. One or more inorganic substances are abstracted and then separatively recovered by retrograde condensations. The process particularly is applicable with mixtures obtained from the chlorination of metalliferous ores and may be conjoined to many ancillary metal abstraction processes such as volatilizations, distillations or electrolyses.

Abstract: Cryolite (Na.sub.3 AlF.sub.6) as a source of aluminum is prepared from coal fly ash by reacting the aluminum oxide (Al.sub.2 O.sub.3) in fly ash with phosphoric acid to form aluminum phosphate, which is then converted to sodium aluminate by reaction with sodium hydroxide, and the sodium aluminate is converted to cryolite by reaction with hydrofluoric acid (HF), or equivalent reagent providing H.sup.+ and F.sup.- ions. Aluminum is thereby obtained from fly ash in a preferred form (as cryolite) for use in producing metallic aluminum.

Abstract: A process for the recovery of soluble alumina values from alumina-bearing ores comprising simultaneously contacting a stream containing an effective amount of a reducing agent such as SO.sub.2 and a stream containing an effective amount of an oxidizing agent such as Cl.sub.2 with an aqueous slurry of the alumina-bearing ores for a time sufficient to remove at least about 50 weight percent of the soluble alumina values from said ores is disclosed.

Abstract: Pure alumina (Al.sub.2 O.sub.3) is recovered from alunite (Al.sub.2 (SO.sub.4).sub.3.K.sub.2 SO.sub.4.4 Al (OH).sub.3) which is found mixed with various impurities by first calcinating the alunite in the presence of a chloride to produce impure Al.sub.2 O.sub.3 and other biproducts, and the impure Al.sub.2 O.sub.3 is then contacted with concentrated HCl to produce, after concentration and crystallization, crystals of AlCl.sub.3.6H.sub.2 O. These crystals are then calcinated to yield highly concentrated HCl and pure alumina.

Abstract: Method of producing aluminiumchloride with a low content of magnesium from hydrochloric acid solutions which contain ions of aluminium and magnesium and from which the aluminiumchloride is precipitated by hydrochloric gas and where the precipitation is carried out continuously in cascade so that the major part of the aluminium will be precipitated from solutions in which the ratio between aluminium and magnesium calculated as g Al.sup.+3 /g Mg.sup.+2 is above 0,5. Produced aluminiumchloride may be transformed to aluminiumoxide by calcination.

Abstract: Method of producing aluminiumchloride with low contents of iron from solutions containing ions of aluminium and iron by precipitation of aluminiumchloride by means of hydrochloric gas where the solution from which the aluminiumchloride is precipitated contains at least 0.1 g Fe/l which solution has been formed by leaching of a natural mineral raw material or artifically produced aluminium-containing raw material by leaching with hydrochloric acid and/or sulphuric acid, respectively a mixture of such acids. The produced aluminiumchloride may be transformed to aluminiumoxide by calcination.

Abstract: Thallous halides, either alone or in combination with other ceramic materials, are used in cryogenic applications such as heat exchange material for the regenerator section of a closed-cycle cryogenic refrigeration section, as stabilizing coatings for superconducting wires, and as dielectric insulating materials. The thallous halides possess unusually large specific heats at low temperatures, have large thermal conductivities, are nonmagnetic, and are nonconductors of electricity. They can be formed into a variety of shapes such as spheres, bars, rods, or the like and can be coated onto substrates.

Abstract: A continuous process for recovering substantially pure aluminum chloride from chlorination products of aluminum ore. The chlorination products are contacted with a first selective solvent to dissolve a substantial portion of the aluminum chloride and some ferric chloride. The solvent is separated from the chlorides which then are treated to produce a ferric chloride-rich stream and an aluminum chloride-rich stream in which the aluminum chloride to ferric chloride ratio is higher than the ratio prior to solvent separation. The aluminum chloride-rich stream is contacted with a second solvent to dissolve any ferric chloride present and saturate the solution with aluminum chloride. Aluminum chloride in excess of that soluble in the second solvent separates as a substantially pure solid phase. The solution is separated from solid phase and recycled in process to recover additional aluminum chloride.

Abstract: The invention described herein relates to a method for improving the acid leachability of aluminum and other metal values found in fly ash which comprises sintering the fly ash, prior to acid leaching, with a calcium sulfate-containing composition at a temperature at which the calcium sulfate is retained in said composition during sintering and for a time sufficient to quantitatively convert the aluminum in said fly ash into an acid-leachable form.

Abstract: Metal ion impurities are removed from phosphoric acid by adding to the acid a precipitant comprising ions of calcium and fluorine to cause precipitation of a magnesium-containing precipitate. A preferred precipitant is one containing calcium flouride, such as the sludge obtained by treating pond water from a phosphoric acid plant with a calcium-containing compound. Preferably, the soluble sulfate content of the phosphoric acid is maintained at at least about 2% by weight. An animal feed can be prepared from the precipitate by combining the precipitate with phosphate rock, water, and a sodium-containing compound, and then calcining the combination.

Abstract: A process for obtaining pure alumina comprising the combination of chlorosulphuric attack of calcined aluminous ores containing impurities, followed by concentration of the liquor obtained after the attack and separation of the sterile material, sulphuric acid treatment of the concentrated liquor followed by chlorination to precipitate almost all the hexahydrated aluminum chloride, separation of the precipitate of hexahydrated aluminum chloride and of the chlorosulphuric mother liquor charged with impurities, pyrohydrolysis of the precipitate to give the desired pure alumina with recycling of released hydrochloric acid, degassing of the chlorosulphuric liquor of impurities with recycling of the gaseous HCl for chlorination, yielding a sulphuric liquor of impurities, finally the elimination of the impurities present in this latter liquor in the form of a sulphuric precipitation by concentration in the presence of potassium ions.

Abstract: A method for producing substantially pure alumina from kaolin clay by removing in a soluble form impurities which contaminate the alumina while the aluminum is maintained in an insoluble form. This is accomplished by leaching calcined kaolin clay with at least 36 weight percent hydrochloric acid to dissolve the impurities and convert the aluminum to insoluble aluminum chloride and maintaining the hydrochloric acid concentration in the leach liquor at at least 36 weight percent by the injection of hydrochloric acid gas. The insoluble aluminum chloride is then separated from the dissolved impurities and subjected to a second leaching step to solubilize and separate it from the silica gangue. Substantially pure AlCl.sub.3.sup.. 6H.sub.2 O crystals are recovered from solution and converted to alumina by conventional means. In an alternate embodiment, the process may be practiced on uncalcined clay and includes the addition of a source of fluoride ions, such as H.sub.2 SiF.sub.

Abstract: A cyclic process for obtaining very pure alumina by the hydrochloric acid attack of a silico-aluminous material, the said process comprising, in a first stage, the precipitation of at most 75% of the alumina present in the liquor originating from the attack in the form of hexahydrated aluminum chloride which is subsequently decomposed by heating, then, in a second stage, the treatment of the liquor leaving the first stage with HCl gas in order to precipitate dissolved Al.sub.2 O.sub.3 in the form of hexahydrated aluminum chloride which is recycled into the liquor leaving the attack, while the hydrochloric liquor leaving the second stage and impoverished in Al.sub.2 O.sub.3 but rich in impurities, is treated with a recycled sulphuric liquor in order to precipitate impurities as their corresponding sulphates.

Abstract: In the process for the preparation of pure aluminum oxide by the steps of hydrochloric acid decomposition of mechanically or thermally activated clay or alumina containing minerals, separating the insoluble residue, removing the iron from the solution, crystallizing the aluminum chloride in the iron-free solution, thermally decomposing the crystallizate to aluminum oxide and recovering the hydrochloric acid from the decomposition gases, the improvement comprising effecting the process by the steps of mechanically pretreating the clay, drying the pretreated clay, thermally or mechanically activating the clay, subjecting the activated clay to circulating leaching, separating the leached material into an SiO.sub.2 containing residue and an AlCl.sub.3 solution, extracting the AlCl.sub.3 solution to an evaporating crystallization and thermally decomposing the crystals to produce .alpha.-Al.sub.2 O.sub.3.

Abstract: A process for obtaining pure aluminum oxide (Al.sub.2 O.sub.3) from siliceous aluminum ore is disclosed. The aluminum ore is digested in a hydrochloric acid solution to obtain aluminum chloride, the aluminum chloride is crystallized as the hexahydrate, the aluminum chloride hexahydrate is purified and, subsequently, decomposed to give pure aluminum oxide and secondary products. The mother liquor of the crystallization step and the secondary products of the decomposition step are recycled.

Abstract: A method of obtaining alumina of high purity from aluminous mineral containing impurities by attacking the mineral with a sulphuric acid liquor and separating the resulting liquor from a residue which remains after the attack, the steps of(a) mixing the resulting liquor with a liquor containing HCl and H.sub.2 SO.sub.4,(b) introducing HCl gas into the mixture,(c) cooling the mixture from step (b) to precipitate hydrated aluminum chlorosulphate crystals having the formula AlSO.sub.4 Cl.6-7H.sub.2 O,(d) separating the hydrated crystals of hydrated aluminum chlorosulphate from the mother liquor,(e) heating the separated crystals to a temperature that does not exceed 600.degree. C.

Abstract: A process for the selective separation of ferric iron from an aluminum fluoride aqueous solution containing ferric iron is effected by contacting said solution with an organic extractant phase consisting essentially of a mixture of a mono (higher alkyl-substituted phenyl) phosphoric acid and a di(higher alkyl-substituted phenyl) phosphoric acid dissolved in an inert diluent to thereby transfer the ferric iron to said organic extractant phase. The efficiency of the process is further improved by adjusting the aluminum fluoride aqueous feed solution to a temperature in the range of about 140.degree. F. to about 175.degree. F. prior to contacting it with the organic extractant phase, maintaining the temperature within this range throughout the ferric iron extraction stage or stages, then heating the resulting iron-depleted aqueous raffinate to a temperature higher than 195.degree. F., and then crystallizing aluminum fluoride trihydrate out of the raffinate at this higher temperature.