Abstract: A structurally modified alumina useful as a catalyst support, or heat transfer solid for fluidized bed synthesis gas processing. A Group IIA metal, or metals, particularly magnesium and barium, is composited with a particulate alumina to provide a catalyst support, or alumina heat transfer solid, having increased resistance to sintering and agglomeration; properties which promote defluidization of the bed in conducting fluidized bed reactions at high temperatures. The particles of preference are represented by formulas (1) and (2), a composite particle being represented by formula (1), as follows:M.sub.x Al.sub.2 O.sub.3+x (1)with the core of the particle being represented by formula (2), as follows:M.sub.y Al.sub.2 O.sub.3+y (2)where in formulas (1) and (2) M is a Group IIA metal, x is a number ranging from about 0.01 to about 0.4 and is representative of the number of moles of the metal M per mole of Al.sub.2 O.sub.3 y is a number equal to or greater than zero, and x is greater than y.

Abstract: Ceramic yttrium aluminate fibers are produced by processes that result in the formation of a microcrystalline ceramic oxide structure. In one process, a stoichiometric amount of a yttrium alkoxide is mixed with an aluminum alkoxide to produce a homogeneous mixture in an alcohol solvent. Following the addition of an alkoxide precursor of ZrO.sub.2 or of HfO.sub.2, the optional addition of an alkoxide precursor of MgO, and the subsequent addition of an organic acid, hydrolytic condensation to produce a suitable sol is accomplished by adding water. A slight excess of yttrium alkoxide can be used instead of the MgO precursor. The viscosity of the sol is adjusted to form a tractable gel that is spun into fibers which, after curing and firing, are shown to be microcrystalline in form, the resulting fibers having a submicron average grain size. Strength and stability result from the presence of solid particles of partially stabilized zirconia or hafnia at the grain boundaries and the triple points.

Abstract: Filamentary abrasive particles formed from a sol-gel alumina modified by rare earth metal oxides have excellent abrasive qualities.

Abstract: Submicron sized ceramic particles are produced by combining a ceramic precursor with an organic or carbonaceous carrier material, and exposing droplets of the mixture to a temperature sufficient to cause combustion of the organic material and subsequent vaporization and nucleation, or diffusion and oxidation, of the ceramic precursor to form pure, crystalline, uniform nanophase ceramic particles.

Abstract: This invention provides a three dimensional inorganic oxide structure comprising a myriad of cavities interconnected by holes having a narrow pore size distribution, in which the diameters of the cavities is in the range from 1 to 50 .mu.m and that of the holes in the range 1 to 10 .mu.m and in which the pore volume in the range 1 to 10 .mu.m is at least 2 cc/g and in which the inorganic oxide is selected from alumina, silica, titania, zirconia and mixtures thereof and a process for the preparation of such structures.

Abstract: A method for fabricating Y.sub.3 Al.sub.5 O.sub.12 (YAG) fibers from water soluble polymers includes a pre-YAG polymer synthesis, with solution viscosity adjustment followed by fiber spinning and heat treatment. The polymer synthesis employs polar solvents such as water or alcohol with a carboxylic acid containing at least two carboxyl groups.

Abstract: A method of making a pillared hydrotalcite and an associated products. The pillared hydrotalcite is made by calcining a hydrotalcite having the formula A.sub.w B.sub.x (OH).sub.y [C].sub.z .multidot.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion and w, x, y, z and n satisfy the following:0<z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x).The method further comprises combining the calcined compound with a salt solution of an anion to make the pillared derivative of the compound and then separating the pillared derivative from the salt solution. A method of intercalating inorganic anions and resulting product is also disclosed.

Abstract: An improved pyroelectric material comprises a polycrystalline material doped with at least one donor element such that the polycrystalline material has a grain size less than 10 .mu.m (or 5 .mu.m) and a Figure of Merit greater than 90 nC/(cm.sup.2.K). In the preferred embodiments the polycrystalline material is barium strontium titanate or calcium-substituted barium strontium titanate. The donor element may be Nb, Ta, Bi, Sb, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er or a combination thereof. The material may additionally be doped with an acceptor such as Co, Cu, Fe, Mn, Ru, Al, Ga, Mg, Sc, K, Na, U, In, Mg, Ni, Yb or a combination thereof to control the resistivity. Other structures and methods are also disclosed.

Abstract: Saltcake generated by the aluminum industry is completely recycled through a process that simultaneously liberates the contained aluminum metal and dissolves the soluble salt fluxes to recover aluminum metal, aluminum oxide and salt fluxes by temperature controlled wet milling, rapid solids-brine separation and solar pond evaporation of the resulting clear brine. The temperature of the feedwater is 70.degree. F. or less to retard the exothermic reaction of aluminum metal with water, thereby minimizing the loss of metal to oxidation and the evolution of undesirable gases. Low temperature is maintained by using process water at or below the desired temperature, by forcibly cooling the mill with ambient air, and by controlling transit time through the mill to avoid excessive grinding of the aluminum metal. Minimizing the production of fine aluminum particles reduces the total surface area of aluminum metal available for exothermic reacton with the water.

Abstract: The ferrates in solid state have the formula:M (Fe, X)O.sub.4in which M designates two atoms of Na or K or one atom of Ca or Ba, and X is an atom whose cation has the electronic structure of a rare gas. These ferrates are isomorphs of ferrates of the formula M FeO.sub.4, in which M has the same definition as above. Used particularly for the treatment of water, by oxidation.

Abstract: A process is provided for the synthesis for metal oxides of high specific surface area and high porosity which are particularly useful as catalyst supports. The process comprises forming a mixture of a salt of at least one metal and a molten salt medium comprising at least one alkali metal salt having an oxidizing effect, maintaining this mixture at the reaction temperature for the time necessary to convert the salt to oxide and thereafter isolating the metal oxide formed.

Abstract: Disclosed is a method for preparing high purity alunite. In the method, a material selected from the group consisting of sodium sulfate, sodium bisulfate, ammonium sulfate, ammonium bisulfate, potassium sulfate and potassium bisulfate is provided and reacted with a source of aluminum hydroxide in a liquid. The reaction is carried out under acidic conditions, and alunite is recovered after separating, washing and drying.

Abstract: The present invention includes metal oxide foam particles and a method of making the same. A decomposable metal salt feed solution is injected into a hot atomizing gas. The mixture of hot atomizing gas and feed solution is maintained in the reactor until the feed solution converts to metal oxide foam particles. The metal oxide foam particles have a high specific surface area.

Abstract: A process for the preparation of stabilized sodium beta"-aluminum oxide from aluminum transition oxides includes applying a phase-stabilizing doping component and another component promoting conductivity and affixing the doping component, to surfaces of aluminum transition oxides and interior areas of pores.

Abstract: A process for preparing lithium aluminate of at least 95% gamma phase with surface areas greater than 10 m.sup.2 /g by homogeneously mixing a gamma lithium aluminate with surface area of less than 8 m.sup.2 /g with an aqueous hydrogen peroxide solution having a concentration of 5 to 70% for at least 1/2 hour at a temperature greater than 0.degree. C. and less than 120.degree. C., the treated gamma lithium aluminate is dried by heating to a temperature greater than 200.degree. C. until dry and ground to produce a gamma-lithium aluminate with surface area greater than 10 m.sup.2 /g.

Abstract: Disclosed is a basic aluminum material having enhanced antiperspirant activity, the material having the empirical formula Al.sub.2 (OH).sub.6-a X.sub.a, where 0.5.ltoreq.a.ltoreq.5.0 and X is a univalent complex oxoanion of nitrogen, chlorine and other halogens, which forms salts with Al.sup.3+ in aqueous solution so that these salts are essentially completely dissociated, which is readily soluble in water with metallic ions in the solution, and which forms conjugate acids that are strong acids; and wherein the material is characterized by:(a) size exclusion high performance liquid chromatography peaks corresponding to peak 3 and peak 4 of size exclusion chromatograms formed by HPLC technique;(b) a peak 4 relative area of at least 25%, a peak 3 relative area of less than 60%, the sum of the relative peak 3 and peak 4 areas being at least 50%; and(c) less than 10% chromatographic peaks eluting at shorter retention times than peak 3, corresponding to peaks 1 and 2.

Abstract: Disclosed is a process for the preparation of double metal oxide ceramic powders which contain at least one metal of Group IIIA, inclusive of aluminum and gallium, and at least one metal of Group IVB, inclusive of titanium and zirconium. The process involves a first step in which an aqueous solution of mixed metal alkoxides or salts is formed and which also contains a chelating agent, preferably a polycarboxylic acid, and a second step in which a base is added in order to cause precipitation of a mixed metal hydroxyl groups-containing precursor that can be calcined or otherwise converted to the final mixed metal oxide. The invention also pertains to novel double metal hydroxyl carboxylates which are useful intermediates in preparing double metal oxides.

Abstract: A process for preparing ceramic powders suitable for pressing into articles comprises the dispersing of a particulate ceramic, preferably of particle size below 1 .mu.m, in water in the presence of ammonia or an alkylamine having a boiling point below that of water and spray - drying the dispersion to give powders. The process is particularly applicable to zirconia and gives rise to fine, free-flowing powders which can be processed into articles of uniform density.

Abstract: Sintered aluminous abrasive grains having a density of at least 95% of theoretical density and having an alpha alumina crystal size of smaller than one micron. Which are obtained by drying and crushing a lithium containing alumina dispersion and sintering the crushed objects at 1100.degree.-1500.degree. C., said abrasive grains have the strength and hardness equal to or higher than conventional abrasive grains, superior properties in grinding resistance and wear resistance and superior self-sharpening property in course of grinding.

Abstract: The present invention provides an aluminum borate ceramic having a high porosity and a tightly controlled pore size distribution, while maintaining good mechanical strength. The ceramic body can be formed by decomposing boric acid-stabilized aluminum acetate to form an aluminum borate powder, and sintering the powder to form a ceramic body.

Abstract: Process for the manufacture of a powder of mixed metal oxides by cohydrolysis of metal alcoholates in the presence of an acidic organic compound and mixed metal oxide powders in which the molar relationships R1 and R2 of a metal oxide to the sum of the metal oxides in the powder and in a particle of the powder are such that ##EQU1## The process applies especially well to powders of zirconia doped with yttrium oxide or other oxides.

Abstract: Aluminum magnesium hydroxy compounds of the formulaAl.sub.x Mg.sub.y (OH).sub.35-z R.sub.z.nH.sub.2 Oin which R represents an anion of at least one monocarboxylic acid having from 2 to 22 carbon atoms, and n, x, y and z are defined by: ##EQU1## are described.

Abstract: An improved process for manufacturing a polycrystalline alumina fiber comprising dissolving aluminum alkoxide in alcohol, adding acetylacetone, hydrolyzing with water, and polymerizing to form a polymeric alumina sol and spinning the polymeric alumina sol by using a spinning apparatus.

Abstract: The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

Abstract: A process for extracting and purifying the gallium contained in an industrial solution of sodium aluminate by fixing the gallium on a stationary phase constituted by porous polystyrene adsorbent resin which is impregnated with an extracting agent, optionally in the presence of a surface-active agent. After elution of the gallium in acid medium, the resultant gallium salt is purified and concentrated so as to be reduced directly to the state of high purity metallic gallium, by electrolysis.

Abstract: A complex oxidation reaction product of two or more metals in an oxidized state is formed by positioning a suitable precursor metal adjacent to a permeable mass of a metal-containing compound in an oxidizing atmosphere and heating the assembly to form a body of molten precursor metal. The molten metal infiltrates the permeable mass and reacts therewith and with the oxidizing atmosphere to form a complex oxidation reaction product. Methods for determining the shape of the resulting article are described. The disclosed methods can be used to form superconducting perovskites.

Abstract: An economical process for the removal and destruction of organic impurities present in Bayer process liquor depends upon the use of a hybrid adsorbent. The hybrid adsorbent consists essentially of porous essentially anhydrous particles of alumina having deposited on the surfaces thereof including the pores, an ultrathin layer of carbon atoms which is essentially monomolecular. Such carbonization is effected by cracking a suitable hydrocarbon, preferably a gas, in contact with a hot turbulent fluidized bed of alumina particles. This layer has the unique property of adsorbing far more impurities than the equivalent weight of active carbon, and also oxalate ions which are known not to be adsorbed on carbon. As an ultrathin layer it is too thin to change either the average pore volume or the surface area of the alumina particles substantially, from before they are carbonized.

Abstract: A process for preparing a cordierite, which includes dissolving a silicon compound, an aluminum compound and a magnesium compound in a molar ratio of 1:0.7 to 1:0.3 to 0.5 in a complexing agent represented by the formula R(OCH.sub.2 CH.sub.2).sub.n OH, wherein R is an alkyl group and n is an integer of 1 to 4; heating the resulting solution to bring about a ligand exchange reaction of the silicon compound, aluminum compound and magnesium compound with the complexing agent; conducting hydrolysis to form a gel; drying the gel and sintering the dried gel at 800.degree. to 1450.degree. C.

Abstract: Zirconium-doped pseudoboehmite with the following properties: zirconium content of 0.5 to 10 mol % relative to Al water content of 20 to 35 weight percent total of the anionic impurities less than 0.5 weight percent. It is synthesized by a process wherein zirconium salt is added in calculated quantity to an aqueous aluminum sulfate solution, the resulting mixture is fed simultaneously with a sodium aluminate liquor into a water pool having a temperature of 50.degree. to 100.degree. C., thereby precipitating zirconium-doped alumina gel while a pH of 3.5 to 8 is maintained, the pH of the suspension is adjusted after addition of the aluminum sulfate solution to 8.5 to 10.5 by further addition of sodium aluminate liquor, the suspension is digested if necessary at the pH of 8.5 to 10.5 and the temperature of 50.degree. to 100.degree. C. for a period of up to 24 hours, the formed pseudoboehmite crystals are filtered off, the filter cake is redispersed with water and the suspension is sprayed-dried.

Abstract: A process for preparing a particulate metal oxide of small particle size wherein a combustible organometallic compound alone or in admixture with a combustible organic liquid carrier is introduced into a combustion zone and combusted in a combustion supporting gas to produce particles of metal oxide, the combustion being carried out under reaction conditions so as to effect calcination of the metal oxide particles prior to condensation of the particles in the bulk phase.

Abstract: A method for treating caustic solutions to remove colorants, including iron, therefrom comprises: contacting the solution with a substance comprising a calcined product of a compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z.nH.sub.2 O, wherein A represents a divalent metal cation; B a trivalent metal cation; C a mono- to tetravalent anion; and w, x, y, z and n satisfying the following: 0<z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x). On a preferred basis, the contacted substance is a hydrotalcite derivative made by reacting activated magnesia with an aqueous solution of aluminate, carbonate, and hydroxyl anions before calcining at one or more temperatures between about 400.degree.-650.degree. C. There is further disclosed a method for producing an aluminum hydroxide having improved whiteness according to the invention.

Abstract: An optoelectronic signal recording and storage medium including a base layer, a conductive layer, a photoconductive layer and storage layer has a coherent crystal morphology throughout, even though the chemical and electrical properties of its layers are by choice dramatically different. The base layer is preferably made of monocrystalline sapphire grown in a manner as to allow the growth of the other layers directly on a surface of the base layer without the need to grind and polish that surface, thereby minimizing internal defects in the medium. The monocrystalline base layer also allows the acceptance of exeptionally uniformly distributed charges over wide areas of the medium, thereby enabling the medium to locally record and store minutely differing optoelectronic signals on a background of minimal noise, thus facilitating low light level electronic or optical recording and long term storage of signals and minimal energy readout of those stored signals.

Abstract: Ceramic precursor mixtures containing a metal cation, a carbohydrate, and an anion capable of participating in an anionic oxidation-reduction reaction with the carbohydrate for continuous or batchwise drying and pyrolyzing to provide ceramic powders.

Abstract: A process for preparing monoclinic celsian from AlF.sub.3, Al.sub.2 O.sub.3, BaCO.sub.3, and fused SiO.sub.2 powders by heating an intimate mixture of the powders (1) at from about 700.degree. to 900.degree. C. to form topaz and then (2) at a temperature as low as 900.degree. C. to produce monoclinic celsian. The reactions take place in an atmosphere of the gases generated by the reactions.

Abstract: A method of producing fine, single-phase YAG particles and fine, single-phase YAG phosphor particles. The method includes subjecting yttrium and aluminum solubilized in an aqueous alkaline solution to a heating reaction at not lower than a predetermined temperature to produce the fine single-phase YAG particles having a uniform particle size distribution. The method also includes adding terbium solubilized in an aqueous alkaline solution as an activating element to the solution of yttrium and aluminum and subjecting this solution to a heating section to produce fine single-phase YAG phosphor particles having a uniform particle size distribution.

Abstract: Zirconia toughened alumina (ZTA) is produced from precursor salts. The precursor salts are coprecipitated from solution to yield a gel in a liquid phase. The gel in excess of the critical temperature and pressure is dried at a temperature and pressure in excess of the critical temperature and pressure of the liquid phase to thereby convert the liquid phase to a gas. The solid particles, when separated from the gas, form a fine particulate ZTA which, upon consolidation yields near theoretical density toughened ceramics.

Abstract: Metal oxide powders, which are chemically uniform and free-flowing, can be formed by dissolving a metal alkoxide in a non-polar organic solvent, adding water to the resulting composition and then emulsifying the blend of water and solvent containing the alkoxide to cause hydrolysis of the alkoxide. The hydrolysis reaction forms the desired metal oxide as a precipitate which can be recovered by a simple filtration process.

Abstract: A method for producing uniform mixed metal oxides, such as superconducting mixtures including Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7-x, in which such metals are precipitated as their oxalates from alcoholic solutions of the metals as the salts of a carboxylic acid.

Abstract: A ceramic article having good fractured toughness comprising substantially spherical ceramic particles, which may be a ceramic oxide such as zirconia or zirconia combined with yttrium oxide. The ceramic particles are compacted and sintered to a density greater than 90 percent of theoretical density. The article is characterized by a substantially uniform chemical composition and a substantially inclusion-free, homogeneous microstructure, which may be a metastable crystalline phase with less than 10 volume percent monoclinic crystalline phase. The article is produced by dissolving, such as in water, a soluble compound containing a metal, e.g. zirconium, to form a solute. A precipitation agent, such as sodium hydroxide or ammonium hydroxide, is combined with the solute to precipitate a hydrophilic colloid of the metal hydroxide, such as zirconium hydroxide. The precipitate is formed into particles which are rapidly solidified while preventing agglomeration thereof.

Abstract: The invention provides new processes for the production of precursor powders for ceramic materials by emulsion precipitation, the new processes permitting the economic production with at least some cations of uniformly small size particles (1 micrometer or less) to result in corresponding dense microstructures upon sintering the precursor powder to produce the ceramic material. The processes require the production of a fine water-in-oil type emulsion of an aqueous solution of the desired cation or cations in a non-miscible liquid, usually an oil, such as a saturated hydrocarbon, a suitable surfactant usually also being employed, The emulsion preferably has an aqueous particle size of 0.1 micrometer or less, produced by a mechanical emulsator. A gaseous reactant, preferably ammonia, or a mixture of ammonia with a neutral diluent gas, is bubbled through the emulsion to contact it and react with the cations, without breaking the emulsion by physical and/or chemical action.

Abstract: A process for preparing monoclinic celsian from topaz and BaCO.sub.3, pows by heating an intimate mixture of the powders at a temperature of from 900.degree. C. to less than 1590.degree. C. in an atmosphere of the gases generated by the monoclinic celsian formation reaction itself.

Abstract: Novel monodispersed crystalline mixed metal layered hydroxide compounds of the general formula are prepared:Li.sub.m D.sub.d T(OH).sub.(m+2d+3+na) A.sub.a.sup.n, where m is an amount from zero to 1; D is a divalent metal; d is the amount of D ions of from zero to 4; T is a trivalent metal; A represents anions or negative-valence radicals of valence n; na is from zero to -3; (m+d) is greater than zero; and (m+2d+3+na) is equal to or greater than 3. The D metal is preferably Mg and the T metal is preferably Al. These compounds are useful as gelling agents which impart beneficial thixotropic properties to various fluids, such as drilling fluids, especially when employed along with fluid loss agents.

Abstract: A simple and effective method for producing bulk single and mixed oxide absorbents and catalysts is disclosed. The method yields bulk single oxide and mixed oxide absorbent and catalyst materials which combine a high macroporosity with relatively high surface area and good mechanical strength. The materials are prepared in a pellet form using as starting compounds, calcined powders of the desired composition and physical properties these powders are crushed to broad particle size distribution, and, optionally may be combined with an inorganic clay binder. The necessary amount of water is added to form a paste which is extruded, dried and heat treated to yield and desired extrudate strength. The physical properties of the extruded materials (density, macroporosity and surface area) are substantially the same as the constituent powder is the temperature of the heat treatment of the extrudates is approximately the same as the calcination temperature of the powder.

Abstract: A novel oxidation catalyst or refractory and the method for its preparation. The material comprises substitutional solid solutions involving V.sub.2 O.sub.3, Al.sub.2 O.sub.3 and TiO.sub.2 and having compositions that fall within a specific polygon in a ternary composition diagram of V.sub.2 O.sub.3, Al.sub.2 O.sub.3 and TiO.sub.2. A typical material has the formula Al.sub.0.65 V.sub.1.77 Ti.sub.0.69 O.sub.5.

Abstract: A crystalline material having, in the dehydrated form, the empirical formula:m(m.sub. 2/a O):X.sub.z O.sub.xz/2 :.sub.y YO.sub.2 (I)in which m is 0.5 to 1.5; M is a cation of valency a; X is a metal of valency x, selected from aluminum, boron, gallium, zinc, iron and titanium; z is 2 when x is an odd number, and z is 1 when x is an even number; y is at least 5; and Y is silicon or germanium; and having, in the calcined hydrogen form, an X-ray diffraction pattern including significant peaks substantially as shown in Table I herein. The material has been designated SUZ-2.

Abstract: A crystalline zeolite SSZ-33 is prepared using a quaternary ion as a template.

Abstract: A process for preparing lactulose from lactose in which an aqueous lactose mixture is reacted with a sodium aluminate solution and the solution obtained is continuously neutralized by feeding this solution and a sulphuric acid solution to a reactor simultaneously in such a manner as to obtain a pH of between 4.5 and 8.By operating in this manner an aluminium hydroxide suspension is obtained which can be easily separated from the lactulose solution.

Abstract: A superconductive material with a superconducting critical temperature of at least 77.degree. K. comprising 20 at. % Nb, 10 at. % Si, 10 at. % Al and 60 at. % O is provided by simultaneous vapor-phase physical deposition or sputtering of Nb, Si and Al onto a heated sapphire substrate under oxygen-containing atmosphere, followed by a rapid quenching or post-oxidization of Nb-Si-Al ternary system composition having an Nb/Si/Al atomic ratio of 2/1/1. The high critical temperature allows abundantly existing, cheap available liquid nitrogen to be used as a cryogen for developing superconductivity.

Abstract: A complex oxidation reaction product of two or more metals in an oxidized state is formed by positioning a suitable precursor metal adjacent to a permeable mass of a metal-containing compound in an oxidizing atmosphere and heating the assembly to form a body of molten precursor metal. The molten metal infiltrates the permeable mass and reacts therewith and with the oxidizing atmosphere to form a complex oxidation reaction product. Methods for determining the shape of the resulting article are described. The disclosed methods can be used to form superconducting perovskites.

Abstract: Disclosed is a method for producing hydrotalcite in high yield including reacting activated magnesia with an aqueous solution containing aluminate, carbonate, and hydroxyl ions. The .[.method further includes a first step of.]. .Iadd.activated magnesia is produced by .Iaddend.heating magnesium carbonate or magnesium hydroxide to a temperature between about 500.degree.-900.degree. C. .[.to form activated magnesia or magnesium oxide..]. The method is suited to producing synthetic hydrotalcite from industrial Bayer liquor.