Abstract: Described herein is an aqueous composition for removing cryolitic deposits from plants or parts of plants which serve for the conversion treatment of metal surfaces, said composition including a) at least one mineral acid, and b) at least one dicarboxylic acid of the formula HOOC—(CH2)x—COOH, where x is 0 to 3 and no borate-containing compounds have been added to the composition. Also described herein is a corresponding method for removing cryolitic deposits.

Abstract: A carrier for an ethylene epoxidation catalyst, the carrier comprising a porous alumina body formed of sintered particles of alumina in a substantial absence of inorganic binder species other than alumina, wherein the substantial absence of inorganic binder species corresponds to an amount of less than 0.6 wt % inorganic binder species other than alumina and comprises at least a substantial absence of silicon-containing species.

Abstract: A process for producing a daughter radionuclide from a parent radionuclide includes a) loading the parent radionuclide on a first solid medium contained in a generator and onto which the parent radionuclide is retained and whereby the daughter radionuclide is formed by radioactive decay of the parent radionuclide; b) eluting this medium with a A0 solution so as to recover a A1 solution comprising the daughter radionuclide; c) optionally adjusting the pH of the A1 solution so as to obtain a A1? solution, d) loading this A1 or A1? solution onto the head of a second solid medium contained in a chromatography column; e) first washing said second solid medium with a A2 solution; f) second washing said second solid medium with a A2? solution; g) eluting the daughter radionuclide with a A3 solution. The first washing step is conducted from head to tail of the column and the second washing step and the second eluting step are conducted from tail to head of the column.

Abstract: A method of purifying a spinel powder includes contacting a spinel powder with an acid solution to form an acid-washed spinel composition and contacting the acid-washed spinel composition with a basic solution to form a purified composition. The purified powder is suited to formation of low-absorption shaped bodies, such as windows for high intensity laser devices.

Abstract: Method of removing cobalt deposits in a reactor for the cobalt-catalyzed high-pressure hydroformylation of olefins by treatment with aqueous nitric acid, wherein the reactor is at least partly filled with aqueous nitric acid and the temperature of the aqueous nitric acid is increased during the treatment.

Abstract: The present disclosure relates to an inorganic, halogen-free flameproofing agent made of modified, rehydrated red mud (MR2S), having a mineral composition of 10 to 50 weight percent of iron compounds, 12 to 35 weight percent of aluminum compounds, 5 to 17 weight percent of silicon compounds, 2 to 21 weight percent of TiO2, and 0.5 to 6 weight percent of calcium compounds, wherein the compounds of iron have a hydroxide and oxide hydrate fraction greater than or equal to 50 weight percent relative to the oxide fraction of the iron compounds, and wherein the compounds of aluminum have a hydroxide and oxide hydrate fraction greater than or equal to 50 weight percent. The disclosure further relates to a flameproofed material system comprising a flammable material and the inorganic, halogen-free flameproofing agent and to a method for the production thereof.

Abstract: The present invention refers to a method being easy to recover metals including nickel and aluminum from waste aluminum catalysts, thereby entirely promoting the recovering rate. Said method comprises: preparing and roasting a waste aluminum catalyst with sodium salts, and then obtaining a first solution comprising vanadium and molybdenum, and a dreg comprising nickel and aluminum through leaching and filtrating; collecting and mixing the dreg with alkali powders to obtain a mixture of the dreg and alkali powders, roasting the mixture at 300 to 1000° C. with aluminum in the dreg reacting with hydroxyl generated from the roasting of mixture and further generating aluminum hydroxide, and then obtaining a second solution comprising aluminum and a concentrate having nickel through another leaching and filtrating; and recovering aluminum from the second solution and recovering nickel from the concentrate.

Abstract: The invention relates to non-ferrous metallurgy and is used for extracting beryllium from genthelvites when processing the raw minerals (ores, concentrates) by heap and vat leaching. The objective of the invention is to disclose a method of leaching beryllium from danalite (Fe8(BeSiO4)6S2), genthelvite (Zn8(BeSiO4)6S2), and helvite (Mg8(BeSiO4)6S2), thus expanding the range of raw minerals used for processing and providing more economical production and improved environmental impact via use of an effective reagent at low temperatures by hydrochemical method. The offered method is beneficial both economically and ecologically, as the alternate modern pyrometallurgical method of beryllium extraction has the following drawbacks: emission of toxic gases, high energy requirements, and use of the fireproof materials. The newly developed method is recommended as a basis for the innovative technology of beryllium extraction from genthelvite concentrates and ores.

Abstract: The invention relates to non-ferrous metallurgy and can be used for extracting beryllium from genthelvite and bertrandite groups when processing the raw minerals (ores, concentrates) by heap and vat leaching. The objective of the invention is to disclose a method of teaching beryllium from danalite (Fe8(BeSiO4)6S2), genthelvite (Zn8(BeSiO4)6S2), helvite (Mg8(BeSiO4)6S2), chrysoberyl, euclase, and bertrandite, thus expanding the range of raw minerals used for processing and providing more economical production and improved environmental impact via use of an effective reagent at low temperatures by hydrochemical method. The offered method is beneficial both economically and ecologically, as the alternate modern pyrometallurgical method of beryllium extraction has the following drawbacks: emission of toxic gases, high energy requirements, and the need for fireproof materials.

Abstract: There are provided processes for treating red mud. For example, the processes can comprise leaching red mud with HCl so as to obtain a leachate comprising ions of a first metal (for example aluminum) and a solid, and separating said solid from said leachate. Several other metals can be extracted from the leachate (Fe, Ni, Co, Mg, rare earth elements, rare metals, etc.). Various other components can be extracted from solid such as TiO2, SiO2 etc.

Abstract: The invention relates to non-ferrous metallurgy and is used for extracting beryllium from genthelvites when processing the raw minerals (ores, concentrates) by heap and vat leaching. The objective of the invention is to disclose a method of leaching beryllium from danalite (Fe8 (BeSiO4) 6S2), genthelvite (Zn8 (BeSiOl) 6S2), and helvite (Mg8 (BeSiO4) 6S2), thus expanding the range of raw minerals used for processing and providing more economical production and improved environmental impact via use of an effective reagent at low temperatures by hydrochemical method. The offered method is beneficial both economically and ecologically, as the alternate modern pyrometallurgical method of beryllium extraction has the following drawbacks: emission of toxic gases, high energy requirements, and use of the fireproof materials. The newly developed method is recommended as a basis for the innovative technology of beryllium extraction from genthelvite concentrates and ores.

Abstract: A process for the extraction of alumina from an aluminum-bearing ore or concentrate, comprising the steps of leaching the aluminum-bearing ore or concentrate with a lixiviant of hydrochloric acid and magnesium chloride at atmospheric pressure at a temperature of from 90° C. to the boiling point of the solution and at an Eh of at least 200 mV. After a liquid/solids separation step, the solution obtained is subjected to steps for removal of iron and for recovery of alumina.

Abstract: There is provided a hydrometallurgical process of recovering indium and gallium values from mixtures thereof with other metal values for example recycled and scrap solar panel cells which comprises subjecting the mixture to strongly oxidizing acid conditions, preferably via the simultaneous addition of sulfuric acid and hydrogen peroxide to the leach vessel, so as to form indium and gallium salt species of at least the major proportion of the indium and gallium values in the mixture, extracting the indium and gallium values with an organic extractant by adjusting the pH so as to extract individually the indium and gallium values with the organic extractant, stripping indium and gallium values from the extractant using an acid and an alkaline solution respectively and recovering the indium and gallium values.

Abstract: A process for neutralization is provided which can maintain a high solid content of a bauxite dissolution residual substance slurry even after a neutralization treatment is completed and the stabilize pH within a short time of the neutralization treatment. Such a process for neutralizing a bauxite dissolution residual substance containing a desiliconizing product which is generated in the production process of aluminum hydroxide using Bayer process, includes: mixing a bauxite dissolution residual substance or a bauxite dissolution residual substance slurry with sulfuric acid in an amount ranging from 0.6 to 1.2 equivalence to the total amount of sodium contained in the bauxite dissolution residual substance or a bauxite dissolution residual substance slurry, such that the solid content after mixing becomes 400 to 700 g/l to gelate the mixture, and thereafter obtaining a bauxite dissolution residual substance neutralized slurry.

Abstract: A method for recycling metals from waste molybdic catalysts, comprises steps of leaching, by soaking a waste molybdic catalyst into a highly oxidized acid and conducting a reaction between sulfur in the waste molybdic catalyst and the acid to obtain sulfide and vaporizer, wherein metals in the waste molybdic catalyst are dissolved and oxidized by the acid to obtain a first solution and dregs; and refining, by further dissolving metals in the dregs into a second solution, and extracting metals in the waste molybdic catalyst from the first and second solution; wherein, the vaporizer obtained from the step of leaching is converted into highly oxidized acid and recycled in the step of leaching.

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, for example, 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: 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: Methods of fabricating nano-catalysts are described. In some embodiments the nano-catalyst is formed from a powder-based substrate material and is some embodiments the nano-catalyst is formed from a solid-based substrate material. In some embodiments the substrate material may include metal, ceramic, or silicon or another metalloid. The nano-catalysts typically have metal nanoparticles disposed adjacent the surface of the substrate material. The methods typically include functionalizing the surface of the substrate material with a chelating agent, such as a chemical having dissociated carboxyl functional groups (—COO), that provides an enhanced affinity for metal ions. The functionalized substrate surface may then be exposed to a chemical solution that contains metal ions. The metal ions are then bound to the substrate material and may then be reduced, such as by a stream of gas that includes hydrogen, to form metal nanoparticles adjacent the surface of the substrate.

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: A method for recovering base metal values from oxide ore is provided, where the ore includes a first group metal selected from nickel, cobalt and copper. The method includes reducing ore particle size to suit the latter unit operation, favoring contact for the metal elements, contacting the ore with ferric or ferrous chloride, hydrated or anhydrous, to produce a mix of ore and iron (II or III) chloride subjecting the mixture of the ore and ferric or ferrous chloride to enough energy to decompose the chlorides into hydrochloric acid and a iron oxides from the second group, forming their respective chlorides, selectively dissolve the produced base metal chlorides, leaving the metal as oxides and in the solid state, and recovering the dissolved base metal values from aqueous solution.

Abstract: A method of purifying an aluminum source includes dissolving an aluminum ion source to provide a first solution including aluminum ions having a pH of not greater than 4.0, adjusting the pH of the first solution with a tetraalkylammonium hydroxide solution to a pH in range of 4.1 to 8.4 thereby forming an aluminum hydroxide precipitate, separating the aluminum hydroxide precipitate from the first solution, washing the separated aluminum hydroxide precipitate with an aqueous solution having a pH in a range of 4.1 to 8.4, dissolving the washed aluminum hydroxide precipitate using an acid to provide a second solution having a pH of not greater than 4.0, and forming an aluminum salt from the second solution.

Abstract: There are provided processes for extracting aluminum ions from aluminous ores. 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: There is provided a method of treating a metalliferrous material, comprising providing a metalliferrous material including at least one target metallic element, solubilising the metalliferrous material so as to effect production of an intermediate product including an operative solution. The operative solution includes a solvent component and a solute component. The solute component includes at least one solute component-based target metallic element and each one of the at least one solute component-based target metallic element corresponds to a one of the at least one target metallic element of the metalliferrous material such that the operative solution includes at least one target metallic element.

Abstract: A mineral processing facility is provided that includes a cogen plant to provide electrical energy and waste heat to the facility and an electrochemical acid generation plant to generate, from a salt, a mineral acid for use in recovering valuable metals.

Abstract: The invention provides a method of inhibiting the accumulation of DSP scale in the liquor circuit of Bayer process equipment. The method includes adding one or more particular silane based small molecules to the liquor fluid circuit. These scale inhibitors reduce DSP scale formation and thereby increase fluid throughput, increase the amount of time Bayer process equipment can be operational and reduce the need for expensive and dangerous acid washes of Bayer process equipment. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.

Abstract: There is provided a process for preparing aluminium chloride comprising leaching aluminium dross residues with H2SO4 so as to obtain a leachate; and hydrochlorinating the leachate so as to obtain aluminium chloride. If desired, aluminium chloride can then be converted into alumina.

Abstract: There are provided processes for extracting aluminum ions from aluminous ores. 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: There is provided a process for preparing aluminium chloride comprising: leaching aluminium dross residues with HCl so as to obtain a mixture comprising a solid and a liquid; and hydrochlorinating the liquid obtained from the mixture, so as to form a precipitate comprising aluminium chloride. Such a sequence can also be used for preparing alumina. In such a case, the process can further comprise the step of converting the so-obtained aluminium chloride into alumina. In the processes previously defined, the solid so-obtained can also be leached with H2SO4, thereby generating a leachate. The leachate can also eventually be hydrochlorinated so as to increase the yield of the desired product obtained i.e. alumina or aluminium chloride.

Abstract: A method for treating an oil shale formation comprising dawsonite includes providing heat from one or more heaters to the formation to heat the formation. Hydrocarbon fluids are produced from the formation. At least some dawsonite in the formation is decomposed with the provided heat. A chelating agent is provided to the formation to dissolve at least some dawsonite decomposition products. The dissolved dawsonite decomposition products are produced from the formation.

Abstract: There is provided a process for preparing aluminium chloride comprising leaching aluminium dross residues with H2SO4 so as to obtain a leachate; and hydrochlorinating the leachate so as to obtain aluminium chloride. If desired, aluminium chloride can then be converted into alumina.

Abstract: THE COMBINED LEACHING PROCESS comprises a dissolution process of the soluble constituents of an ore by means of the combined execution of two or more serial leaching phases with the first phase comprising atmospheric leaching (AL) and the second one pressure leaching (HPAL). This combined process takes place when the intermediate size fraction (0.075-0.5 mm) is submitted to atmospheric leaching (AL), ensuing an effluent with a high concentration of dissolved iron and aluminum as well as high residual acidity. This said effluent is fed in the following acid pressure leaching (HPAL) phase of the fine size fraction (<0.075 mm) and at reusing free acidity, regenerating the sulfuric acid through iron and aluminum precipitation in a hydrolysis reaction, and bringing forth a considerable reduction in the addition of sulfuric acid.

Abstract: There is provided a process for preparing aluminium chloride comprising: leaching aluminium dross residues with HCl so as to obtain a mixture comprising a solid and a liquid; and hydrochlorinating the liquid obtained from the mixture, so as to form a precipitate comprising aluminium chloride. Such a sequence can also be used for preparing alumina. In such a case, the process can further comprise the step of converting the so-obtained aluminium chloride into alumina. In the processes previously defined, the solid so-obtained can also be leached with H2SO4, thereby generating a leachate. The leachate can also eventually be hydrochlorinated so as to increase the yield of the desired product obtained i.e. alumina or aluminium chloride.

Abstract: A method for the production of inorganic aluminum substances and amorphous silica from aluminum oxide containing ores, comprising: (a) leaching of said ores with fluorosilicic acid to obtain aluminum fluosilicate solution; (b) filtering said leached solution from insoluble materials; and (c) washing said insoluble materials.

Abstract: A process for upgrading of titaniferous material containing silica, including pretreating the titaniferous material by alkaline leaching to precipitate the silica as an aluminosilicate which is amenable to further leaching. Subsequently, the pretreated titaniferous material is leached under acid conditions, causing the silica to enter solution under conditions such that the silica is not hydrolysed or precipitated as a silicate.

Abstract: A method for producing small spherical particles that are especially useful as catalysts and catalyst supports employed in chemical processes is disclosed. According to some embodiments, the method includes impregnating a porous support with a metal or metal oxide and dissolving the support to release spherical particles. In certain embodiments the support that is employed in the method comprises a number of spherical voids which determine the size of the spherical particles, and preferably have micrometer range diameters. One embodiment of an attrition resistant Fischer-Tropsch catalyst comprises a plurality of micrometer size spherical metal and/or metal oxide particles that are prepared according to the above-described method.

Abstract: A process is described for the treatment of spent pot lining material from electrolyte reduction cells, this spent material having a substantial content of cryolite. The spent material is first leached with water at a dilution and a time sufficient to dissolve substantially all water soluble fluorides, after which the solid residue is separated from the liquid. The solid residue obtained is then subjected to a caustic leach with an aqueous sodium hydroxide solution containing about 20 to 50 g/L of NaOH and thereafter the solid residue is separated from the liquid.

Abstract: A process for the production of alumina is performed by dissolving gibbsite Al2O3.3H2O in nitric acid to provide an acid solution containing aluminum nitrate; decomposing the acid solution at 300-700° C. with a free air supply to form alumina and Nox by spraying onto the inner surface of one or more rotary kilns, drying in a fluid bed, or drying in a steel belt conveyor furnace; regenerating the formed NOx into concentrated nitric acid and recycling the nitric acid to be used for the dissolving of gibbsite; and recovering the alumina formed upon decomposing the acid solution.

Abstract: A method for processing alumina-bearing ores such as bauxite to recover iron, aluminum, silicon and titanium metal values therefrom the method comprising the steps of adding the alumina-bearing ores to a digester containing an acid to provide a mixture of acid and alumina-bearing ores and heating the mixture to dissolve soluble compounds of at least one of iron, aluminum, silicon and titanium to provide a digest containing dissolved salts of the soluble compounds and to provide a gas component. Thereafter, the digest is treated with water to dissolve water soluble salts therein to provide a slurry comprised of a liquid containing water and the dissolved soluble salts and a solid component comprised of silica. The solid component is separated from the liquid and the pH of the liquid is adjusted to form an aluminate and an iron-containing precipitate.

Abstract: A method of extracting active mineral liquid from a rock such as granite is described. This method comprises charging an extraction vessel with finely divided granite at ambient temperature and pressure; introducing an aqueous ammonia solution with agitating and then diluted sulfuric acid into the vessel; introducing 98% ethyl alcohol at below 80° C. into the vessel to elevate the inner pressure of the vessel to 2-3 kg/cm2 for facilitating the formation of complexes; and agitating the resulting reaction mixture for 20-160 minutes at 80° C. to 85° C. while maintaining the internal pressure of the vessel. The active mineral liquid is advantageously used as a mineral source for soils, animals, plants, the human body and so forth, and as an agent for the purification of waterworks as well as for the treatment of wastewater.

Abstract: A process for the extraction of alumina, iron oxide and titanium dioxide from bauxite ore and clays, and other ore bodies and feedstocks. The process starts by sulfuric acid leaching of the feedstocks in pressure autoclaves at about 200° C. and appropriate pressure. A leach liquor of sulfate salts of aluminum, iron and titanium is obtained. Any iron values are converted to a ferrous state. A recycled potassium sulfate helps produce double aluminum alkali sulfate crystals in the reduced leach liquor. The crystals are removed at about 20°-60° C. with the help of SO2 gases that reduce the ferric. Such double salt is hydrolyzed into a basic aluminum alkali precipitated sulfate salt. This is then dried and calcined at about 950° C. Any alkali sulfate is washed out and recycled. The remainder is alumina. The ferrous sulfate is crystallized out at about 10° C. It is dried and calcined at about 450° C. to produce an iron oxide mixed with other sulfate salts that can be washed out and recycled.

Abstract: A material with high surface area can be obtained through the partial or total removal of CaO and MgO by acid leaching of blast furnace slag. This is accomplished by an improved process for selective leaching of blast furnace slag and other solid solution materials by control of temperature during leaching, rate of addition of acid, type of the acid, concentration of the acid, and concentration of the slag in the slurry. When these variables are controlled as disclosed a hierarchy of dissolution occurs. The hierarchy begins with MgO, progresses to CaO, and is followed by A12O3, and the rate of acid addition is slow and controlled so that alumina does not dissolve (thereby depriving the remaining silica has no acid sites or catalytic activity). By invoking the hierarchy one gains selectivity, and this can be used to convert blast furnace slag to a material with high surface area which may have applications as an absorbent could be economically feasible.

Abstract: A method for processing red mud to recover iron, aluminum, silicon and titanium metal values therefrom the method comprising the steps of adding the red mud to a digester containing an acid to provide a mixture of acid and red mud and heating the mixture to dissolve soluble compounds of at least one of iron, aluminum, silicon and titanium to provide a digest containing dissolved salts of the soluble compounds and to provide a gas component. Thereafter, the digest is treated with water to dissolve water soluble salts therein to provide a slurry comprised of a liquid containing water and the dissolved soluble salts and a solid component comprised of silica. The solid component is separated from the liquid and the pH of the liquid is adjusted to form an aluminate and an iron-containing precipitate.

Abstract: A method of recovering chloride and sulfate salts from spent potliner using acid digestion.

Abstract: Spent potliner from aluminum reduction cells is treated, for example, with sulfuric acid to recover carbon, silica and alumina or to recover a vitrified product of silca and alumina.

Abstract: A method for producing fumed silica and a fluorine-containing product from a source of silica in solid form and a solid material containing fluorine, the solid material selected from the group consisting of sodium aluminum tetrafluoride, cryolite, aluminum fluosilicate ammonium bifluoride, sodium aluminum silicofluoride, and sodium fluosilicate. The method comprises the steps of digesting the silica in solid form and the solid material selected from the group consisting of sodium aluminum tetrafluoride, cryolite, aluminum fluosilicate, ammonium bifluoride, sodium aluminum silicofluoride, and sodium flurosilicate in a sulfuric acid digester. The digestion step produces a first gas component comprised of silicon tetrafluoride, hydrogen fluoride and water vapor. The first gas component is removed from the digester.

Abstract: Spent potliner from an aluminum reduction cell is subject to an acid digest and the digest may be adjusted to produce a first gas component comprised of at least one material selected from the group consisting of silicon tetrafluoride, hydrogen fluoride, hydrogen cyanide gas and water vapor, and a slurry component comprised of at least one material selected from the group consisting of carbon, silica, alumina, and sodium, iron, calcium and magnesium compounds. The first gas component is removed from the digester and heated to a temperature sufficiently high to convert said silicon tetrafluoride to fumed silica and hydrogen fluoride. Thereafter, the fumed silica is separated from the hydrogen fluoride to recover fumed silica from spent potliner material.

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 which allows the conversion of clay minerals of the kalonite group, to a relatively pure form of alumina and silica respectively comprising the steps of (a) heating the kaolinite group minerals to greater than 500.degree. C., which causes dehydroxylation of the crystallographic lattice and formation of an intermediate meta-kaolin; (b) reacting the intermediate with only one of a selection of reagents including acids, alkalines or metalliferous compounds followed by heating of the mixture to form an aluminium salt in solution and residue of silica; (c) separation of the aluminium salt solution from the residue of silica by filtration and further treatment of the silica residue to produce a relatively pure form of fine particled silica; (d) formation of an alum by addition of ammonium sulphate in solution to the aluminium salt solution and further treatment of the alum to produce a relatively pure form of aluminium hydroxide.

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 recovering one of alumina hydrate, magnesium hydroxide and magnesium aluminate spinel (MgAl.sub.2 O.sub.4) from aluminum dross wherein the dross is processed to a non-metallic product (NMP). The dross may contain fluxing salts which are removed in providing the NMP. The NMP may be derived from aluminum dross which does not contain fluxing salts sometimes referred to as white dross. The process comprises digesting the non-metallic product with an acid selected from the group consisting of sulfuric, hydrochloric, hydrofluoric and phosphoric acid or mixtures thereof to provide a slurry containing dissolved alumina, magnesia and a solid component, for example, containing magnesium aluminate spinel. Instead of an acid, a base such as sodium hydroxide may be used. The slurry is filtered to separate the solid component from the liquid containing dissolved constituents such as alumina and magnesia to recover the solid component.