Abstract: Structures and methods for the fabrication of ceramic nanostructures. Structures include metal particles, preferably comprising copper, disposed on a ceramic substrate. The structures are heated, preferably in the presence of microwaves, to a temperature that softens the metal particles and preferably forms a pool of molten ceramic under the softened metal particle. A nano-generator is created wherein ceramic material diffuses through the molten particle and forms ceramic nanostructures on a polar site of the metal particle. The nanostructures may comprise silica, alumina, titania, or compounds or mixtures thereof.

Abstract: A method for producing an ?-alumina particulate is described. The method for producing an ?-alumina particulate comprises steps of (Ia) and (Ib), or a step of (II): (Ia) removing water from a mixture containing water, a seed crystal and a hydrolysate obtained by hydrolysis of an aluminum compound under conditions of a pH of 5 or less and a temperature of 60° C. or less, (Ib) calcining the resulted powder, (II) calcining a mixed powder containing 75-1 wt % of an ?-alumina precursor (in terms of Al2O3) and 25-99 wt % of a seed crystal (in terms of oxide of metal component).

Abstract: A new class of supermicroporous mixed oxides, with pore sizes in the 10-20 ? range has been prepared utilizing basic metal acetates. The reactions are carried out in non-aqueous solvent media to which an excess of amine is added. Hydrolysis of the reagents is effected by addition of a water-propanol mixture and refluxing. The amine and solvent are removed by thorough washing and/or calcining at temperatures as low as 200° C. Mixtures of transition metal oxides with either ZrO2, TiO2, La2O3, SiO2, Al2O3 or mixtures thereof were prepared. The surface area curves of the pure oxides are Type I with surface areas of 400-600 m2/g and up to 1100 m2/g for the mixed oxides.

Abstract: Methods of producing nanoporous particles by spray pyrolysis of a precursor composition including a reactive precursor salt and a nonreactive matrix salt are provided, wherein the matrix salt is used as a templating medium. Nanoporous aluminum oxide particles produced by the methods are also provided.

Abstract: Method for the production of a finely crystalline boehmite and application of said boehmite as flame retardant in plastics. The abstract of the disclosure is submitted herewith as required by 37 C.F.R. §1.72(b). As stated in 37 C.F.R. §1.72(b): A brief abstract of the technical disclosure in the specification must commence on a separate sheet, preferably following the claims, under the heading “Abstract of the Disclosure.” The purpose of the abstract is to enable the Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure. The abstract shall not be used for interpreting the scope of the claims. Therefore, any statements made relating to the abstract are not intended to limit the claims in any manner and should not be interpreted as limiting the claims in any manner.

Abstract: The inventive method for producing refractory high-strength spherical granules consists in separately presintering kaolin and bauxite in a rotational furnace, jointly sintering said components in order to produce a charging material, granulating, drying and screening said charging material, sintering said granules in the rotational furnace and screening the sintered granules. Said sintered kaoline is produced by sintering at a temperature ranging from 1400 to 1500 DEG C so far as a water absorption of 5% is attained for kaoline containing 40-45 mass % and a free quartz in a quantity equal to or greater than 60 mass %. The Al2O3:SiO2 ratio in the charging material is equal to 1:1 at the following charging material component ratio: 36-67 mass % sintered kaolin and the rest being sintered bauxite.

Abstract: A method for producing a hydrorefining catalyst of the present invention has a step of preparing an aluminum solution containing phosphorus in a molar ratio of 0.001 to 0.05 with respect to aluminum; a step of neutralizing the prepared aluminum solution to produce a pseudo-boehmite powder; a step of forming the pseudo-boehmite powder followed by performing calcination at a temperature of not less than 650° C. to obtain a carrier; and a step of carrying a hydrogenation-active metal on the pseudo-boehmite powder or the carrier. The dispersion of the concentration distribution of phosphorus in the carrier of the obtained catalyst is within 10%. This method makes it possible to obtain the hydrorefining catalyst which has a practically sufficient mechanical strength and which has an excellent activity.

Abstract: Provided are methods of preparing a separator for an electrochemical cell comprising the steps of (a) coating onto a substrate a liquid mixture comprising an inorganic oxide, an organic polymer, a divinyl ether of an ethylene glycol, and/or an organic carbonate; (b) drying the coating; and (c) delaminating the coating from the substrate to form the separator comprising an inorganic oxide and the organic polymer, wherein the inorganic oxide of step (c) comprises a reaction product of the divinyl ether and/or the organic carbonate with the inorganic oxide of step (a). Preferably, the inorganic oxide of step (c) comprises a hydrated aluminum oxide of the formula Al2O3.H2O, wherein x is less than 1.0, and wherein the hydrated aluminum oxide comprises a reaction product of the divinyl ether and/or organic carbonate with the inorganic oxide of step (a), such as pseudo-boehmite.

Abstract: Pyrogenically produced aluminum-silicon mixed oxides with a BET surface of more than 300 m2/g and a composition of 0.01 to 99.99% by wt. AI2O3, remainder SiO2 are produced in accordance with the method of flame pyrolysis or preferably flame hydrolysis by a joint combustion of the gaseous raw substances. They can be used to produce coating colors, especially for inkjet papers or inkjet foils or other inkjet materials.

Abstract: A method for fabricating an ?-Al2O3 powder with a size distribution substantially ranging from 30 nm to 100 nm, wherein the method comprises the following steps: First, at least one transition phase Al2O3 crystallite is provided, and then a coating process is conducted on the Al2O3 crystallite coating an aluminum compound on the Al2O3 crystallite to form a plurality of agglomerates having a size distribution substantially ranging from 50 nm to 200 nm. Subsequently, the agglomerates are thermally treated to form ?-Al2O3 powder.

Abstract: Disclosed is a process for preparing fine metal oxide particles, comprising the following steps of reacting a reactant mixture comprising i) water, ii) at least one water-soluble metal nitrate and iii) ammonia or ammonium salt at 250–700° C. under 180–550 bar for 0.01 sec to 10 min in a reaction zone to synthesize the metal oxide particles, the metal nitrate being contained at an amount of 0.01–20 wt % in the reactant mixture; and separating and recovering the metal oxide particles from the resulting reaction products. According to the present invention, nano-sized metal oxide particles are synthesized, while the harmful by-products generated concurrently therewith are effectively decomposed in the same reactor.

Abstract: To provide a process for producing an aluminum oxide powder, whereby the content of impurities is controlled by a physical means. A process for producing an aluminum oxide powder, which comprises pulverizing electrofused alumina by a batch system and classifying the obtained pulverized product to obtain an aluminum oxide powder different in the content of impurities. It is possible to obtain aluminum oxide of high purity by pulverization to a smaller average particle size and separating a powder having a larger average particle size by classification.

Abstract: Pressed material such as anodes are described and formed from oxygen reduced oxide powders using additives, such as binders and/or lubricants. Methods to form the pressed material are also described, such as with the use of atomizing, spray drying, fluid bed processing, microencapsulation, and/or coacervation.

Abstract: A method for the production of aluminum from bauxites containing aluminum monohydate of the diaspore or boehmite type which may contain more than 1.5% by weight of calcium carbonates. The ore is digested by producing feeding a suspension produced from milled bauxite ore and concentrated aluminate liquor to a plant with a series of autoclaves and a series of regulators supplying tubular reheaters across the autoclaves with steam. The suspension first travels across the series of autoclaves, and on exiting, the digestion of the ore is practically complete, and the suspension then travels across the series of regulators. The condensation water from the steam coming from the regulator and feeding the reheater is collected in a purge pot. Within the series of regulators, the suspension is diluted on entering a regulator with the water coming from the condensation of the steam from one or several upstream regulators.

Abstract: Methods of preparing a polymerization catalyst are provided that include contacting a support comprising alumina with a sulfating agent and with chromium. In an embodiment in which the chromium is provided from a chromium compound such as chromium oxide, the support may be calcined after loading the sulfating agent and the chromium on the support. Alternatively, the sulfating agent can be loaded on the support while calcining it. In another embodiment in which the chromium is provided from an organochromium compound, the support may be calcined after contacting it with the sulfating agent and before contacting it with the organochromium compound. Catalysts compositions formed by the foregoing method are provided. In an embodiment, catalyst compositions comprise chromium and a sulfate treated alumina support. The catalyst compositions have an activity for ethylene polymerization that is at least about 25% greater than an activity of the same catalyst without sulfate.

Abstract: Composite microparticles having thin coating layers can be simply prepared by bringing a host particle precursor into contact with a flame generated in a burner movably mounted at the bottom of a coating apparatus, by introducing the precursor in the form of a vapor or micronized liquid droplets upwardly into the burner, to obtain host particles; and introducing a gaseous coating precursor upwardly toward the host particles in or around the flame, the coating precursor being protected by an inert gas introduced therearound such that the formation of particles derived from the coating precursor itself is prevented.

Abstract: Mesoporous aluminum oxides with high surface areas have been synthesized using inexpensive, small organic templating agents instead of surfactants. Optionally, some of the aluminum can be framework-substituted by one or more other elements. The material has high thermal stability and possesses a three-dimensionally randomly connected mesopore network with continuously tunable pore sizes. This material can be used as catalysts for dehydration, hydrotreating, hydrogenation, catalytic reforming, steam reforming, amination, Fischer-Tropsch synthesis and Diels-Alder synthesis, etc.

Abstract: A method of preparing spherical pellets from a slurry comprising a ceramic powder, a solvent, and any desired additives, by means of a drop-generating orifice to which said slurry is fed is described, wherein the drops are released from said orifice by means of a relative flow of a liquid medium which is a poor solvent for the solvent of the slurry, formed into spherical bodies in said liquid medium by means of the action of surface tension, and thereafter treated for consolidation. More specifically, the present invention relates to the preparation of pellets of a catalyst or catalyst support material, suitable for use in high temperature conditions.

Abstract: The present invention pertains to a quasi-crystalline boehmite containing additive in a homogeneously dispersed state. Suitable additives are compounds containing elements selected from the group of alkaline earth metals, alkaline metals, rare earth metals, transition metals, actinides, silicon, gallium, boron, titanium, and phosphorus. Said QCBs according to the invention may be prepared in several ways. In general, a quasi-crystalline boehmite precursor and an additive are converted to a quasi-crystalline boehmite containing the additive in a homogeneously dispersed state.

Abstract: A method for producing nanostructured multi-component or doped oxide particles and the particles produced therein. The process includes the steps of (i) dissolving salts of cations, which are either dopants or components of the final oxide, in an organic solvent; (ii) adding a dispersion of nanoparticles of a single component oxide to the liquid solution; (iii) heating the liquid solution to facilitate diffusion of cations into the nanoparticles; (iv) separating the solids from the liquid solution; and (v) heat treating the solids either to form the desired crystal structure in case of multi-component oxide or to render the homogeneous distribution of dopant cation in the host oxide structure. The process produces nanocrystalline multi-component or doped oxide nanoparticles with a particle size of 5–500 nm, more preferably 20–100 nm; the collection of particles have an average secondary (or aggregate) particle size is in the range of 25–2000 nm, preferably of less than 500 nm.

Abstract: This invention relates to filtration particulate material for the removal of compounds from fluid streams. More particularly, this invention relates to a composition for filtration particulate material, method of manufacture of the filtration particulate material, filtration particulate material and the use of the filtration particulate material for the removal of compounds from fluid streams.

Abstract: A method of manufacturing a powder, by which it is possible to adjust the strength of the obtained powder is provided. The manufacturing method of a powder involves a step of preparing a slurry containing agglomerated particles of a synthetic material which is produced by reacting a first material and a second material under agitation, and a step of drying the slurry to obtain a powder of the synthetic material. The method has a feature that the particle size of the agglomerated particles is adjusted by, in the step of preparing a slurry, controlling agitation power for agitating the slurry. In the step of preparing a slurry, it is preferable that the slurry is initially agitated at a first agitation power, and at the time when the viscosity of the slurry approaches its maximum value, or at the time when the pH value of the slurry reaches the vicinity of the isoelectric point of the synthetic material, the agitation power is lowered from the first agitation power to a second agitation power.

Abstract: A method of producing hollow alumina particles in which the grain size of hollow alumina particles is controlled and in which a high formation ratio of hollow particles is obtained while suppressing the formation of solid particles. The method includes irradiating supersonic waves to an aqueous solution containing aluminum nitrate or aluminum acetate, and a surfactant or an organic acid to generate micro-liquid droplets in an atomized state, introducing only minute liquid droplets having a certain grain size or less, which have been classified by an air stream, into a furnace and burning them in air.

Abstract: The invention provides alumina agglomerates of the type obtained by dehydrating an aluminum hydroxide or oxyhydroxide, agglomerating the alumina obtained, hydrothermally treating the agglomerates and calcining. The invention also provides a catalyst support, an adsorbent material and a catalyst constituted by said agglomerates. The invention also provides methods for preparing said agglomerates.

Abstract: The invention concerns an additive-containing ground calcined alumina used as constituent of a refractory material precursor characterized in that it comprises an organofunctional silane, the organic function being typically an epoxy function, an alkyl function, an alcohol function or a diol function. Preferably said organofunctional silane is an oxyranyl-alkyl-silane, of chemical formula C9H20O5Si. Said additive-containing alumina can be obtained by adding said organofunctional silane during grinding to take advantage of its anti-caking properties, the intimate and homogeneous mixture being obtained as a result of grinding. It may also result from a post-grinding mixing.

Abstract: In a metal oxide nanoparticle and a synthetic method thereof, and in particular to maghemite (?-Fe2O3) nanoparticles usable as a superhigh density magnetic recording substance by having good shape anisotropy and magnetic characteristics, hematite (?-Fe2O3) nanoparticles usable as a precursor to the maghemite or a catalyst, maghemite and hematite-mixed nanoparticles and a synthetic method thereof, the method for synthesizing metal oxide nanoparticles includes forming a reverse micelle solution by adding distilled water, a surfactant and a solvent to metallic salt not less than trivalent, precipitating and separating gel type amorphous metal oxide particles by adding proton scavenger to the reverse micelle solution; adjusting a molar ratio of metal oxide to the surfactant by washing the gel type amorphous metal oxide particles with a polar solvent; and crystallizing metal oxide nanoparticles through heating or reflux after dispersing the gel type amorphous metal oxide particles in a non-polar solvent having a h

Abstract: A method of making an oxide compound, comprising subjecting a base material to a source of heat that produces a localized temperature in the range of 2,000 to 5,500 degrees Celsius that vaporizes the base material which is drawn upward above the surface of the base material where it oxidizes, after which the resulting oxide compound is collected. A method of making bismuth trioxide, comprising providing an electric arc between electrodes, wherein elemental bismuth is in touching proximity to one of the electrodes. The bismuth is evaporated, drawn upward off the surface of the molten metal, forms the bismuth oxide on contact with oxygen, and the particles of bismuth oxide are collected. A method of making an oxide using an electric arc to evaporate a base material which then reacts with oxygen, and collecting the resulting oxides of base material.

Abstract: The present invention relates to a preparation method of ?-alumina nano powder, and more particularly to a preparation method of ?-alumina nano powder that has a uniform particle shape and size distribution, is capable of being produced at a low temperature, and contains less than 20 ppm of alkali metals such as Na and K. the ?-alumina nano powder is prepared by glycolating aluminium alkoxide in glycol solution containing the ?-iron oxide or ?-alumina nucleation seed and carrying out glyco thermal reaction.

Abstract: A method for producing ferrite hollow particles having a hollow structure formed by mutual sintering of ferrite powder, including: a) a step of mixing a resin powder and a ferrite powder of a particle size smaller than that of the resin powder under compaction thereby forming ferrite powder-coated particles in which ferrite powder coats, in a partially embedded state, surface of the resin powder; and b) a step of heat treating the obtained ferrite powder-coated particles thereby removing the resin powder and mutually sintering the ferrite powder.

Abstract: A process for producing nano sized boehmite aluminas which are stable at alkaline pH values wherein an aqueous medium of a peptized boehmite alumina is treated with a water dispersible polycarboxylic acid polymer and optionally with an organic water dispersible base having a molecular weight ranging from 500 to 3000 and having no more than three basic groupings to produce a treated boehmite alumina which forms a stable sol at a pH of greater than 6, the treated boehmite alumina having a dispersed particle size of less than 500 nm in the sol.

Abstract: The present invention relates to a metal oxide powder for high precision polishing and prepartion thereof, comprising aggregates formed by cohesion of primary particles, which has a cohesive degree (?) of 1.1 to 2.0 and a cohesive scale (?) of 3 to 10, the cohesive degree (?) and the cohesive scale (?) being defined by formula (I) and formula (II), respectively: ?=6/(S×?×d(XRD)) ??(I) ?=weight average particle diameter/d(XRD) ??(II) wherein, S is the specific surface area of the powder; ?, the density; and d(XRD), the particle diameter of the powder determined by X-ray diffraction analysis. In accordance with the present invention, it is possible to provide a high polishing speed and reduce scratches.

Abstract: The invention relates to alumina agglomerates of the type obtained by dehydrating an aluminium oxyhydroxide or hydroxide, agglomerating the alumina thus obtained, hydrothermally treating the agglomerates and calcinating same. Said agglomerates are characterised in that: the V37 ? thereof is greater than or equal to 75 ml/100 g, preferably greater than or equal to 80 ml/100 g and, better still, greater than or equal to 85 ml/100 g; the V0.1 ?m thereof is less than or equal to 31 ml/100 g; and the V0.2 ?m thereof is less than or equal to 20 ml/100 g, preferably less than or equal to 15 ml/100 g and, better still, less than or equal to 10 ml/100 g. The invention also relates to a catalyst carrier, an intrinsic catalyst or an absorbent, in particular for use in the petroleum and petrochemical industry, comprising such alumina agglomerates. Moreover, the invention relates to methods for preparing said agglomerates.

Abstract: Mesoporous crystalline alumina compositions and process for the preparation thereof are described. The compositions are useful as catalysts and absorbents.

Abstract: A process of treating metal oxide nanoparticles that includes mixing metal oxide nanoparticles, a solvent, and a surface treatment agent that is preferably a silane or siloxane is described. The treated metal oxide nanoparticles are rendered hydrophobic by the surface treatment agent being surface attached thereto, and are preferably dispersed in a hydrophobic aromatic polymer binder of a charge transport layer of a photoreceptor, whereby ?—? interactions can be formed between the organic moieties on the surface of the nanoparticles and the aromatic components of the binder polymer to achieve a stable dispersion of the nanoparticles in the polymer that is substantially free of large sized agglomerations.

Abstract: A method for producing ?-alumina powder is described. The method comprises the steps of removing water from a compound containing the following (1), (2), (3) and (4), and calcining the results: (1) ?-alumina precursor, (2) seed crystal, (3) water, (4) nitrate ion in an amount of from 2.8 to 3.3 mol per mol of aluminum (Al) contained in the ?-alumina precursor and the seed crystal.

Abstract: A process for producing alumina particles, comprising vaporizing aluminum chloride to form an aluminum chloride vaporized gas, which optionally contains an inert gas, and oxidizing the vaporized aluminum chloride with an oxidizing gas to produce alumina particles, wherein the aluminum chloride vaporized gas and the oxidizing gas are introduced into a reactor each at an ejecting flow velocity of about 10 m/sec or more, the ratio of the flow velocity of oxidizing gas to the flow velocity of the aluminum chloride vaporized gas is approximately from 0.2 to less than 10, and the amount of oxidizing gas is about 1 or more times the amount of oxidizing gas necessary for stoichiometrically oxidizing aluminum chloride.

Abstract: Flake-like ?-alumina particles having an average major diameter of 0.5 to 25 ?m and an aspect ratio, expressed by particle major diameter/average thickness, of greater than 50 to 2000 and having a thin flat form. The flake-like ?-alumina particles are produced by a hydrothermal synthesis process of an aqueous slurry in which the slurry comprises an alumina hydrate and/or an alumina gel, having a particle size of not more than 2 ?m and a maximum size of not more than 5.0 ?m and phosphoric acid ions in an amount of 1.0×10?3 to 1.0×10?1 mol per mol of the alumina hydrate and/or alumina gel. The flake-like ?-alumina particles exhibit good dispersibility when being kneaded as fillers or pigments in rubbers or plastics or as coating agents with a resin and also can be easily dispersed as primary particles in aqueous solvent with high dispersion stability when added to an aqueous slurry of precision abrasives or cosmetics.

Abstract: A process for producing roundish alumina particles includes the steps of granulating a composition containing at least one pulverized product of electrofused alumina and sintered alumina having a mean particle size of 5 to 35 ?m and at least one species selected from the group consisting of a halogen compound, a boron compound and an alumina hydrate to obtain a granulated product, heating the granulated product at 1,000 to 1,600° C., and crushing the heated product.

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: Nanoscale corundum powders are obtained by first producing an Al2O3 precursor by adding seed crystals to an aqueous solution of an aluminium compound and adding a base and then converting the Al2O3 precursor into corundum by calcination at a high temperature. Before the calcination, the salts that are present in addition to the Al2O3 precursor are separated off. The resulting product is calcined at temperatures of 700 to 975° C. and any fines that may be present are removed. The resulting corundum powders can be sintered at temperatures of ?1200° C. to produce compacts or components of multiple layer systems.

Abstract: Polycrystalline materials of macroscopic size exhibiting Single-Crystal-Like properties are formed from a plurality of Single-Crystal Particles, having Self-Aligning morphologies and optionally ling morphology, bonded together and aligned along at least one, and up to three, crystallographic directions.

Abstract: High-surface-area alumina honeycombs are subjected to a water vapor pre-treatment to obtain protection from cracking damage on subsequent exposure to aqueous media e.g., aqueous solutions for depositing catalysts on the honeycombs.

Abstract: A method of synthesizing metal alkoxide polymers is provided, for use, as an example, in synthesizing hybrid organic/inorganic materials with low optical absorption for optical applications. The method involves a plurality of acidolysis steps involving acidolysis of a metal alkoxide compound with an acid to produce an intermediate acidolysed solution, and combining and condensing the intermediate acidolysed solutions to produce the metal alkoxide polymer.

Abstract: A method of producing alumina having a low soda content and excellent sintering properties includes the steps of adding a soda removal agent to alumina source material and calcining the alumina source material in a calciner (2), using a dust collector (5) to collect calcined alumina source material dust contained in the exhaust gas, discharging a portion of the collected dust out of the system, slurrying another portion of the collected dust in a slurrifier (10) while controlling slurry pH, washing and filtering the slurried dust and recirculating it back to the calciner, recirculating still another portion of the collected dust together with a mineralizing agent to the calciner, and removing the low soda alumina after the calcination.

Abstract: An inorganic oxide powder is produced by a method which comprises a step of (i) introducing, into a dry-way pulverizer, an inorganic oxide in an amount of 100 parts by volume and air, nitrogen or a gas mixture thereof in an amount of from about 25,000 to about 160,000 parts by volume to pulverize the inorganic oxide by the dry-way pulverizer, or (ii) introducing, into a medium-stirring-type pulverizer, an inorganic oxide with a BET specific surface area of from about 1 to about 70 m2/g to pulverize the inorganic oxide by the medium-stirring-type pulverizer in a dry way at a specific energy consumption of from about 0.3 to about 1 kWh/kg. The inorganic oxide powder is capable of providing a ceramic with high density and high mechanical strength.

Abstract: A method for producing a hydrorefining catalyst is used to produce the hydrorefining catalyst which contains an inorganic oxide carrier and a hydrogenation-active metal and which has such a bimodal pore characteristic that pores having pore diameters of not more than 50 nm have a pore volume of not less than 0.4 cm3/g, pores having pore diameters of not less than 50 nm have a pore volume of not less than 0.2 cm3/g, and pores having pore diameters of not less than 1000 nm have a pore volume of not more than 0.1 cm3/g. The method comprises the steps of mixing and forming a pseudo-boehmite powder having a dispersibility index of 0.13 to 0.28, and calcinating the formed pseudo-boehmite under a condition in which the pseudo-boehmite is converted into ?-alumina. The hydrorefining catalyst, which has the bimodal pore characteristic, can be produced easily at low cost.

Abstract: Disclosed is a process for the elimination of volatile, foul-smelling organic compounds which are liberated in a gas suspension calciner process utilized to manufacture alumina. The process comprises recirculating captured alumina dust on which undesirable volatile organic compounds are adsorbed to a location in the manufacturing process (1) at or upstream (based on the path of the conveying gases) from the gas suspension calciner and (2) which is operating at a temperature of about 700 ° C. or higher. The adsorbed organic compounds are stripped off the alumina dust and are subsequently directed by process air into the gas suspension calciner furnace which is operating above 1000 ° C. under oxidizing conditions. Under such conditions the organic compounds are oxidized to H2O vapor and CO2. It is a preferred feature that the volatilized organic compounds are adsorbed on the alumina dust in a baghouse.

Abstract: A process for producing roundish alumina particles includes heating at 1,000 to 1,600° C. a composition containing at least one of electrofused alumina and sintered alumina having a mean particle size greater than 35 ?m, and at least one species selected from the group consisting of a halogen compound, a boron compound and an alumina hydrate; and crushing the composition.

Abstract: In a BAYER circuit, a process for controlling precipitation in which particle size quality of alumina hydrate produced in the circuit and circulating in feed tanks is monitored utilizing a calibration step and a control step. In the calibration step, cumulative percentage of alumina hydrate particles circulating in the feed tanks in the circuit that are finer than X2 ?m, defined as CPFT X2, is measured vs. time and cumulative percentage of alumina hydrate particles circulating in the feed tanks in the circuit that are finer that X1 ?m, defined as CPFT X1 vs. time, is measured, where X1 and X2 are predetermined particles sizes and X1 is smaller than X2. A relationship R between CPFT X1 and later changes in CPFT X2, is determined and upper and lower trigger thresholds of CPFT X1 which correspond to maximum permissible variation in CPFT X2 are defined. In the control step, CPFT X1 and CPFT X2 are regularly measured, and R and the correlation between CPFT X2 and the particle size of hydrate produced are updated.

Abstract: Pyrogenically prepared silica doped with silver or silver oxide is prepared by feeding an aerosol into a flame such as is used for the preparation of pyrogenic silica, mixing the aerosol homogeneously with gas mixture before the reaction, then allowing the aerosol/gas mixture to react in a flame. The resulting pyrogenic silicas doped with silver or silver oxide are separated from the gas stream. The pyrogenic silica doped with silver or silver oxide by means of an aerosol can be used as a bactericidal filler.