Abstract: An abrasive grain made from melted spherical corundum where the abrasive grain consists of a spherical corundum core, coated with an encircling layer of a binder and fine-grained abrasive solid particles.

Abstract: Aluminum oxide powder in the form of aggregates of primary-particles, which has a BET surface area of from 10 to 90 m2/g and comprises as crystalline phases, in addition to gamma-aluminum oxide and/or theta-aluminum oxide, at least 30% of delta-aluminum oxide. It is prepared by vaporizing aluminum chloride and burning the vapor together with hydrogen and air, the ratio of primary air/secondary air being 0.01 to 2, the exit speed vB of the reaction mixture from the burner being at least 10 m/s, the lambda value being 1 to 4, the gamma value being 1 to 3 and the value of gamma*vB/lambda being greater than or equal to 55. Dispersion comprising the aluminum oxide powder. Coating composition comprising the dispersion.

Abstract: ?-Alumina powder of fine particles having the primary particle diameters of from 10 nm to 100 nm, and of a high ratio of ?-phase and further having capability to provide a sintered body with high density, and a method of manufacturing the ?-alumina powder is provided. The method for manufacturing the ?-alumina powder comprises a step of mixing an aluminum compound which is the precursor for the corresponding ?-alumina and at least one selected from the group consisting of a titanium compound, an iron compound, a chromium compound, and ?-alumina, and aluminum nitride, aluminum carbide and a aluminum boride as a seed crystal(s), and a step of calcining the mixture at a temperature of from 600° C. to 1000° C. in the presence of HCl gas in an concentration of 1% by volume to 20% by volume.

Abstract: A method of treating spent potliner material from aluminum reduction cells is disclosed. The spent potliner material is introduced into a sulfuric acid digester to produce a gas component including hydrogen fluoride and hydrogen cyanide and a slurry component including carbon, silica, alumina, sodium sulfate, iron, calcium and magnesium. The gas component is recovered and heated an effective amount to eliminate hydrogen cyanide and produce a remaining gas component including CO.sub.2, H.sub.2 O, nitrogen oxides and HF. The remaining gas component is directed through a water scrubber to form hydrofluoric acid, and the hydrofluoric acid is admixed with aluminum hydroxide to create aluminum fluoride. The slurry component is rinsed with water to separate a first solid fraction containing carbon, alumina and silica from a second liquid faction. The pH of the liquid fraction is adjusted to first create and separate aluminum hydroxide and then to separate sodium sulfate.

Abstract: An integrated process for the treatment of spent catalysts containing mainly molybdenum, vanadium, nickel, cobalt and, alumina to produce ammonium metavanadate, vanadium pentoxide, molybdic trioxide, fused alumina and a high grade nickel/cobalt alloy essentially free of aluminum.

Abstract: Monoclinic celsian (BaO.Al.sub.2 O.sub.3.2SiO.sub.2) is produced by heating a stoichiometric, powder mixture of BaCO.sub.3 (or BaC.sub.2 O.sub.4), Al.sub.2 O.sub.3, and SiO.sub.2 (preferably SiO.sub.2 gel) with monoclinic celsian seeds at from 1250.degree. C. to 1500.degree. C.

Abstract: A new transition alumina is made by heating substantially pure diaspore in a vacuum to an elevated temperature of about 300-1000.degree. C. The new transition alumina has increased surface area compared with alpha-alumina formed by heating diaspore in air.

Abstract: A process for recovering heavy metals from spent catalysts on an alumina support material comprising calcining the catalyst feed material to remove impurities and smelting the calcined feed in an electric arc furnace, preferably with scrap iron. A reducing agent, such as natural gas, is injected into the furnace to reduce the heavy metals to their metallic states. The reduced metals form an alloy and separate from the alumina by gravity.

Abstract: Aluminium chloride contaminated with iron chloride is purified by contacting it in vapor form with a bed of particles of aluminium metal interspersed with particles of a chemically inert material. The efficiency of the process may be maintained by acid treating, drying and recycling the bed material. The process may be applied to aluminium chloride produced by the chlorination of a bauxite beneficiate.

Abstract: A method for preparing compounds of sulfur, selenium, and tellurium includes the formation of the compound from the elements in a closed environment which excludes oxygen, and then the purification of the compound by contacting it with carbon or carbon monoxide. Oxygen, the principal contaminant in conventionally prepared compounds of this group, is excluded from the formation of the compound in the formation step by using a closed reactor, preferably made of vitreous silica. Oxygen in the initial elemental reactants remains in the compound made in this way, and the purification step eliminates the oxygen originally present in the elemental reactants from the compound. Arsenic triselenide made by this approach, glassy and of high purity, is suitable for use in applications requiring infrared transparency.

Abstract: Ultra-fine spherical particles of a metal oxide having an average particle diameter of 40 nm or smaller can be prepared by a method in which a vaporizable metal compound is vaporized and decomposed under heating to give ultra-fine particles of a metal oxide followed by immediate cooling down to a temperature at which coalescence of the fine particles are prevented from coalescence. The fine particles have characteristics such as an excellent power of ultraviolet scattering.

Abstract: A product suitable as a ceramic comprises substantially nonaggregated alumina particles with 95% by number having an aspect ratio (i.e., the ratio of the longest dimension to the shortest dimension for any single particle) not greater than 1.1 and more than 80% having an aspect ratio not greater than 1.05 and having a geometric mean size of from 0.02 to 0.5 microns. Usually the product contains no more than 3% by weight as aggregates and preferably the product is as small as can conveniently be manufactured.

Abstract: A method is disclosed for recovering gallium and/or germanium from fly ash which comprises pelletizing the fly ash, treating the pellets in the presence of an oxidizing gas at a temperature of from about 900.degree. C. to just below the fusion temperature of the pellets, treating the pellets in the presence of a reducing gas at the same temperature range, and recovering gallium and/or germanium suboxides from the gas.

Abstract: The invention relates to a process for deironing red mud and bauxite and for the preparation of a raw material for alumina industry and of iron pentacarbonyl which comprises(a) activating the red mud or bauxite starting material at 150.degree.-800.degree. C. under a pressure of 0.1-100 bars in a reducing gas stream in the presence of one or more promoter(s) and thereafter(b) carbonylating at 50.degree.-300.degree. C. under a pressure of 25-300 bars with carbon monoxide or a gas containing carbon monoxide and removing the iron pentacarbonyl formed from the system.The advantage of the present invention is that it provides a process for the effective removal of the iron content of red mud or bauxite and moreover it enables the utilization of the removed iron in the valuable form of iron pentacarbonyl which is suitable for use in iron metallurgy.

Abstract: A method for separating and recovering substantially pure aluminum, iron and silica from fly ash, a by-product of coal combustion, includes reacting the fly ash with aqueous fluosilicic acid and aqueous hydrogen fluoride at temperatures sufficiently high to form aqueous silicon fluoride vapor and fluorides and fluosilicate of aluminum and iron, separating the aluminum and iron fluorides and fluorosilicates from the aqueous silicon fluoride vapor, hydrolizing the silicon fluoride vapor to form silicon dioxide in substantially pure form and hydrogen fluoride, recovering and recycling the hydrogen fluoride for reuse in the process, and separating the aluminum and iron fluorides and fluosilicates from one another, and recovering substantially pure aluminum fluoride, substantially pure iron and other substantially pure metals, by electroplating or otherwise.

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

Abstract: In the fluidized bed chlorination of oxidic materials, for example minerals such as bauxite, tantalite, columbite, wolframite or scheelite, the separation of metal values giving vaporous chlorides at the reaction temperature is enhanced by maintaining a zone substantially free of chlorine in the fluidized bed, for example a zone at least 0.25 m in depth measured from the expanded bed surface. A high aspect ratio bed and counter current movement of the bed matter and the chlorine within the bed are preferably used.

Abstract: At least a two-stage chlorination system for the production of a substantially iron-free alumina-silica product from Bauxites and Clays wherein in a preferred embodiment of the invention the chlorination agent is selected from the group consisting of Cl.sub.2, HCl and COCl.sub.2 in the first chlorination stage and wherein in the second chlorination stage the chlorination agent is selected from the group consisting of AlCl.sub.3 and SiCl.sub.4.

Abstract: At least a single stage chlorination system for the production of a substantially iron-free alumina-silica product from Bauxites, Bauxitic Clays and Clays wherein at least one chlorination agent is selected from the group consisting of Cl.sub.2, HCl and COCl.sub.2 and at least one chlorination agent from the group consisting of AlCl.sub.3 and SiCl.sub.4.

Abstract: At least a two stage chlorination system for the production of aluminum trichloride and aluminum monochloride wherein in the gas stream containing the highest percentages of aluminum chloride produced CO.sub.2 is present and the said gas stream is passed through a charcoal or devolatilized coke bed in a preferred temperature range of about 1000.degree. C. to 1600.degree. C. to convert the said CO.sub.2 to CO and cycling at least part of the said CO produced to at least the second chlorination stage.

Abstract: At least a single stage chlorination system for the production of a substantially iron-free alumina-silica product from Bauxites, Bauxitic Clays and Clays wherein at least one chlorination agent is selected from the group consisting of Cl.sub.2, COCl.sub.2, AlCl.sub.2, AlCl, SiCl.sub.4 and SiCl.sub.2 and wherein the said chlorination agent is a limited percentage of the total gas stream.

Abstract: A method for producing aluminum chloride suitable for direct introduction into an aluminum chloride reduction cell by treatment of the gas stream emerging from an aluminum value source chlorination process comprising the steps of:1. reducing and condensing iron chloride in one or more iron chloride condensation stages;2. absorbing the aluminum chloride contained in the gas stream under high temperature conditions with an alkali chloride or alkali chloride mixture to form an ionic alkali chloride-aluminum chloride complex; and3. selectively condensing the chlorides from the product by step (2) to produce a purified aluminum chloride-alkali chloride complex suitable for direct introduction into an aluminum chloride reduction cell.

Abstract: A method for purifying with respect to iron, aluminum chloride produced via the chlorination of aluminum bearing ores or materials which also contain iron. The process comprising the steps of:1. chlorinating the aluminum value containing material in a manner which produces a gaseous product containing both ferric chloride and aluminum chloride;2. oxidizing at least a portion of the ferric chloride to particulate iron oxide;3. removing the iron oxide from the gaseous product;4. reducing any remaining ferric chloride to ferrous chloride, using reduced iron oxide, e.g. iron powder;5. condensing the ferrous chloride along with at least about 10% of the available aluminum chloride to assure removal of substantially all iron chloride; and6. condensing the remaining about 80% of the available aluminum chloride as pure product.

Abstract: A method for the production of reduction cell grade alumina from alkali metal/aluminum chloride complexes comprising the steps of:A. reacting the alkali metal/aluminum chloride complexes with oxygen in a three phase fluidized bed comprising:(I) as a solid phase, particles or pebbles of alumina of at least about 1/16" in average diameter;(II) as a gaseous phase oxygen fed at a rate to provide a fluidizing gas velocity above about 8'/sec.; and(III) as a liquid phase coating the particles of alumina an alkali metal/aluminum chloride complexes; andB. separating the product solids from the gases exiting the fluidized bed.

Abstract: A process for the removal of iron and titanium minerals from aluminum bearing materials in at least one chlorination stage by the use of an excess of aluminum trichloride as at least the major chlorinating agent for the contained iron and titanium minerals, condensing the excess aluminum trichloride to recover the aluminum trichloride in an impure form, and recycling the impure aluminum trichloride to the chlorination stage together with additional aluminum trichloride or starvation amounts of chlorine, or alternately additional amounts of aluminum trichloride and starvation amounts of chlorine.

Abstract: The invention relates to a method of recovering the chlorine values from iron chloride obtained from the chlorination of an aluminous material containing iron oxide, such as bauxite. The method involves partially dechlorinating ferric chloride in the presence of a reducing agent to form products comprising ferrous chloride and a chloride compound derived from the reducing agent and oxidizing ferrous chloride at a temperature of about 300.degree. C. to 1200.degree. C. to form products comprising ferric chloride and ferric oxide. The ferric chloride is recycled and the chlorine values are recovered as the chloride of the reducing agent which is suitable for recycle to the aluminous chlorination stage or has other industrial utility.

Abstract: A method of producing aluminum chloride from aluminous materials containing compounds of iron, titanium and silicon comprising reacting the aluminous materials with carbon and a chlorine-containing gas at a temperature of about 900.degree. K. to form a gaseous mixture containing chlorides of aluminum, iron, titanium and silicon and oxides of carbon; cooling the gaseous mixture to a temperature of about 400.degree. K. or lower to condense the aluminum chlorides and iron chlorides while titanium chloride and silicon chloride remain in the gas phase to effect a separation thereof; heating the mixture of iron chlorides and aluminum chlorides to a temperature of about 800.degree. K. to form gaseous aluminum chlorides and iron chlorides; passing the heated gases into intimate contact with aluminum sulfide to precipitate solid iron sulfide and to form additional gaseous aluminum chlorides; and separating the gaseous aluminum chloride from the solid iron sulfide.

Abstract: A process for the selective removal of iron from a ferruginous ore which comprises feeding the dried heated ore into a countercurrent reactor comprising a sulphidizing zone, an intermediate zone and a chlorination zone, through which zones the ore moves in sequence and wherein(a) in the sulphidizing zone, a reductant is introduced and the iron values present in the ore react selectively with sulphur and/or volatile sulphur-containing compounds in the presence of the reductant to form iron sulphides;(b) in the intermediate zone, volatile ferric chloride formed in the chlorinating zone is introduced and reacts with the sulphidized ore to convert the iron sulphides into ferrous chloride and reform the sulphur and/or volatile sulphur containing compounds;(c) in the chlorination zone, chlorine is introduced and converts the ferrous chloride formed in the intermediate zone into volatile ferric chloride;(d) the volatile iron chlorides and the upgraded host oxide are separately removed from the chlorination zone; and

Abstract: Fluoridic spent and waste materials, such as are generated in electrolytic aluminum reduction systems, are pyrohydrolyzed in a fluidized bed reactor. For fluidization of these materials, as well as for the combustion of carbon present in the materials, an O.sub.2 -containing gas stream, containing at least about 90% by volume O.sub.2, is employed. This results in the generation of an HF-containing offgas of significantly increased HF level, which can be employed for the manufacture of an AlF.sub.3 product of at least about 85% by weight AlF.sub.3 content from hydrated alumina. The offgas having the increased HF content can also be employed for the production of highly concentrated HF acid with significantly lower energy requirement needed for concentration than in conventional systems.

Abstract: An improved process is provided for the recovery of HF in increased yield from spent aluminum reduction cell linings. The spent linings are pyrohydrolyzed in a fluidized bed reactor and the generated Na-containing vapors and gases are then contacted with a relatively finely divided source of Al.sub.2 O.sub.3. Contacting is preferably accomplished in the close vicinity of the fluidized bed to obtain extended reaction between the Al.sub.2 O.sub.3 source and the vapors. This extended reaction allows conversion of the Na-containing compounds, such as NaF and Na.sub.2 O to HF and an Na.sub.2 OxAl.sub.2 O.sub.3 compound.

Abstract: A pyrohydrolysis system is provided for the recovery of valuable components from waste and spent materials generated in electrolytic aluminum reduction facilities. The pyrohydrolysis system employs a dense phase fluidized bed reaction zone for the pyrohydrolysis of coarse feed, a dilute phase fluidized reaction zone for pyrohydrolyzing fine feed, this zone being superimposed and interconnected with the dense phase zone. The offgases, after removal of the solids, are contacted in a dilute phase fluidized zone, with a source of Al.sub.2 O.sub.3 to remove residual Na values and to produce Na-free HF. The solids from the first dilute zone, having a desired high Na:Al atom ratio, can be combined with the product clinker from the dense bed zone. The offgas, containing the source of Al.sub.2 O.sub.3, is subjected to solids separation, the solids-free and Na-free HF is utilized, while the solids of low Na:Al mole ratio are recycled to the residual Na conversion step.

Abstract: A process for removing silicon from a silicate-bearing material. The silicate-bearing material is analyzed for its silicon content and mixed with a controlled quantity of carbon as indicated by the analysis. The carbon is limited to an amount less than the stoichiometric amount necessary to react with the silicon to form silicon carbide. The silicate-bearing material/carbon mixture is formed into a first phase and interposed with a second phase containing additional carbon to form a reaction mixture. The reaction mixture is subjected to a carbothermal reduction reaction to reduce silica in the silicate-bearing material to silicon monoxide. At the temperatures involved in the reaction, the silicon monoxide is in the gaseous phase and readily diffuses from the first phase into the second phase where the diffused silicon monoxide reacts with the additional carbon in the second phase to form silicon carbide.

Abstract: A fully integrated process is provided for the recovery of valuable components from waste materials generated in electrolytic aluminum reduction systems. The waste materials, such as spent pot linings, channel and trench cleanings, floor sweepings and spent alumina from offgas purifying dry scrubbers, are combined, then pyrohydrolyzed at elevated temperature. Fluoridic values, such as NaF and HF can be recovered from the offgas generated by pyrohydrolysis, while alumina and Na.sub.2 O values, or if desired, sodium aluminate, is reclaimed from the solid residue of pyrohydrolysis.The fluoridic values from the pyrohydrolysis offgas can be used for the manufacture of both electrolytes for aluminum reduction cells and also for the production of anhydrous HF. The alumina from the pyrohydrolysis residue can be reclaimed by a Bayer process-type leach with a caustic solution and the recovered high purity alumina utilized, for example, as reduction cell feed and/or for scrubbing reduction cell offgases.