Abstract: An adsorptive-filtration media for the capture of waterborne or airborne constituents. The media comprises a granular substrate and an amphoteric compound bonded to the substrate in the presence of a crystal inhibiting agent. The media can also comprise a substrate having a specific gravity of less than 1.0 and an amphoteric compound bonded to the substrate. Another media comprises a substrate with a specific surface area of greater than 0.1 m2/gm and an amphoteric compound bonded to the substrate. Another media includes a granular substrate and a manganese oxide amphoteric compound formed on the substrate. Also disclosed is a pavement material for the capture of waterborne constituents. The pavement material comprises a porous pavement substrate and an amphoteric compound bonded to the substrate. Also disclosed is a method for producing a porous, cementitious material.

Abstract: The invention relates to a method of preparing an aluminum-containing iron oxide nucleus with an &agr;-FeOOH crystal structure from FeCl2. This nucleus is a suitable starting material for the preparation of iron oxide yellow and for use as a yellow coloring pigment.

Abstract: Process for the preparation of a vanadium phosphate catalyst comprising treatment of a vanadium compound with formic acid, water and a phosphorus compound.

Abstract: A process for preparing phase stabilized ammonium nitrate comprises the following steps. A solution of ammonium nitrate (12), a phase stabilizer (26), and an inert liquid (20) is prepared. The solution is atomized to form a stream of droplets. The droplets (54) are freeze dried to form phase stabilized ammonium nitrate.

Abstract: A method for stabilizing silica gel wherein after the gel is precipitated it is treated in a solution consisting of a liquid which is preferably water, aluminium sulphate and a compound such as a carbonate, hydroxide or oxide of a divalent metal.

Abstract: The invention relates to a process for the production, by fluid-bed spray granulation, of granular sodium percarbonate having a low TAM value. According to the invention, in the fluid-bed spray granulation, an Mg compound in a quantity of 50 to 2,000 ppm, in particular 100 to 1,000 ppm, or/and a complexing agent from among the hydroxycarboxylic acids, aminocarboxylic acids, aminophosphonic acids and phosphonocarboxylic acids, hydroxyphosphonic acids and their alkali metal salts, ammonium salts or Mg salts, in a quantity of 50 to 2,000 ppm, in particular 200 to 1,000 ppm, are added as stabilisers to the soda solution and/or H2O2 solution. Preferably a combination of an Mg compound in a quantity of 100 to 1,000 ppm Mg2+ and waterglass in a quantity of 0.1 to 1 wt.%, in particular 0.1 to 0.5 wt.%, is used, and in this case granules having a TAM value of about or below 6 &mgr;W/g and simultaneously a short dissolving time, are obtainable.

Abstract: The invention relates to a novel sodium percarbonate in the form of agglomerates of small crystals. The average particle size of the agglomerates is greater than 600 &mgr;m. The apparent density of the agglomerates is between 0.75 g/cm3 and 1.1 g/cm3, and the active oxygen is greater than 14%. The invention also relates to a process for the continuous manufacture of sodium percarbonate in a fluidized bed.

Abstract: A manufacturing method of spinel type manganese oxide for a lithium ion secondary cell, includes pre-firing a mixture of lithium salt including lithium carbonate, manganese oxide, and heterogeneous metal, firing the mixture at 900 to 1200° C. to form a raw material, adding in the raw material at least one of crystal growth accelerators selected from the group consisting of lithium hydroxide, lithium sulfide and a mixture thereof, and firing the resulting compound at 750 to 850° C. to form an excess lithium heterogeneous metal-doped spinel compound having a BET specific surface area of 0.5 m2/g or less.

Abstract: A unitary structure containing a vertically integrated system for deodorizing composting gaseous effluents using scrubbers packed with means providing both extensive surface area for microorganism growth sites and cascading dispersion of microorganism-impregnated liquid media while concomitantly providing sufficient void space to permit substantially unimpeded flow of effluents undergoing treatment within the system.

Abstract: The present invention relates to a process for easily and efficiently producing silica particles having a narrow particle size distribution and a high porosity from inexpensive starting materials such as sodium silicate. The silica particles of the present invention can be obtained in the form of a slurry containing them by (1) forming a slurry by mixing first particles difficultly soluble in an alkali and soluble in an acid, with an aqueous alkali silicate solution to form a first slurry containing the first particles, (2) neutralizing the first slurry with a mineral acid to prepare a second slurry containing second particles wherein silica is deposited on the first particles, and (3) adding a mineral acid to the second slurry to dissolve the first particles from the second particles, to prepare a third slurry containing silica particles.

Abstract: An improved method of purifying sodium carbonate from a natural source whereby a dissolved sodium carbonate product is treated with a cationic compound, such as a quaternary amine, to react with carbon-containing contaminants and filtering the product. The filtered modified sodium carbonate solution is then crystallized and dried. The modified sodium carbonate has a greater reactivity or uptake of carbon dioxide for the manufacture of sodium bicarbonate than conventional sodium carbonates.

Abstract: Alumina particles having high dispersibility and plasticity, at least on the surface of which a phosphoric acid or phosphate is present and suitable for use as a material for pigments for paints, precision abrasives or ceramics. The alumina particles are produced by adding a crystallization inhibitor containing at least phosphate ion to aluminum hydroxide or alumina hydrate and then conducting a hydrothermal synthesis treatment. The amount of the phosphate ion to be added is in the range of 3.0×10−3 to 2.5×10−2 mol per mol of aluminum hydroxide or alumina hydrate. The particle size of aluminum hydroxide or alumina hydrate is 0.1 to 5.0 &mgr;m. The hydrothermal synthesis is preferably conducted at 350° C. or above under a pressure of 50 to 200 atm and at a temperature elevation rate of 5° C./min to 0.3° C./min. The thus obtained alumina is &agr;-alumina in the form of hexagonal plate single crystal having a particle size of 0.

Abstract: A stabilized lime slurry for treatment of biological solids in sewage. The composition preferably includes 30-36% calcium hydroxide, 10-16% potassium hydroxide, 2-4% potassium chloride, 2-4% magnesium hydroxide, all on a dry basis, and the balance in water. This composition raises the pH rapidly for destroying pathogens, is sufficiently concentrated for economically feasible transportation, and reduces the cost, difficulties and dangers of treating sewage with a lime based composition while providing a resulting product from the sewage treatment process which can be spread upon agricultural soil in a manner which improves soil fertility without introducing undesirable or contaminating materials into the soil.

Abstract: The present invention relates to a calcium carbonate composition having both calcite and aragonite crystalline morphology. More particularly, the present invention relates to an acicular calcite and an acicular aragonite product and a method for the production of the same and the use of such as fillers, additives and modifiers of consumer and commercial products such as toothpaste, paper, plastics and sealants.The acicular calcite/aragonite composition of the present invention provides a balance of properties such as sheet bulk, strength, stiffness, and sizing, when employed as a filler for paper. As a coating pigment, the acicular calcite/aragonite product of the present invention provides gloss characteristics suitable for dull and matte grades of low gloss coated paper. Upon further processing such as milling, grinding, or other means of comminution, the resulting product provides gloss characteristics suitable for high gloss coated paper.

Abstract: A new method for improving the mechanical properties and nonlinear optical performance characteristics of gallium selenide crystals (GaSe) is disclosed. A charge of GaSe crystals was doped with indium before being made into a crystal. The indium-doped GaSe crystals have improved physical properties in that they can be cut along the cleave planes and the cleaved surfaces polished without the usual delaminations typically observed in prior art pure GaSe crystals. The indium-doped crystals were tested in a second harmonic generation (SHG) system and found to have nearly twice the SHG efficiency as pure, or undoped, GaSe crystals.

Abstract: The invention is directed to a method for producing low sintering fine-particle multicomponent glass powder having a particle size of the primary particle in the nanometer range. The method utilizes microemulsion techniques with subsequent separation of the particles out of the emulsion and calcination for utilization as glass flow having a sintering temperature <900.degree. C. or in a glass flow, for generating thin transparent layers or for generating color decorations on glass, glass ceramic or ceramic substrates after adding a coloring pigment to the glass flow. The microemulsion for producing the nanoscale glass powder particles is generated from a nonionic ambiphilic emulsifier with a component of 10 to 15 percent by weight on the emulsion, from an oil phase having a portion of 50 to 70 percent by weight and a glass precursor-containing aqueous salt solution having a portion of up to 31.3 percent by weight with salt contents of up to 45 percent by weight.

Abstract: Unique colorant compositions, well suited for the pigmentation of a wide variety of coatings and substrates, e.g., cosmetics, plastics, paints and rubbers, comprise (1) at least one crystalline rare earth metal sulfide or sesquisulfide, for example cubic cerium sesquisulfide Ce.sub.2 S.sub.3, and (2) a dopant amount of at least one alkali metal, and wherein the at least one rare earth metal sulfide or sesquisulfide comprises whole (unground) monocrystalline grains thereof having a mean particle size of at most 1.5 .mu.m.

Abstract: A stable amorphous rare earth oxide, such as Y.sub.2 O.sub.3, including a stabilizer, such as carbon, silicon carbide, or hafnium oxide. The stable amorphous rare earth oxide can be used in a dielectric layer in a magneto-optical recording medium.

Abstract: According to the present invention, a method is provided for preparing physical development nuclei for use in silver salt diffusion transfer processing, said physical development nuclei comprising a heavy metal sulphide, said method comprising the steps of:precipitating said heavy metal sulphide by bringing a water soluble heavy metal compound in reactive association with a water soluble sulphide in an aqueous liquid andsaid precipitation being carried out in the presence of a hydrophilic polymer so as to disperse said heavy metal sulphide, said hydrophilic polymer comprising a heterocyclic group, characterized in that said heterocyclic group is present in a recurring unit of said hydrophilic polymer, said recurring unit being comprised in said polymer in an amount between 0.1 mol % and 5 mol %.

Abstract: The object of the invention is a process for preparing a crystalline, stable sodium percarbonate, in which polymers of gross formulas (I or II) are added in the preparation process to control the crystal form of the sodium percarbonate and to coat the crystals, the molecular weight of the polymers varying in the range from 500 to 1,000,000 g/mol, or salts of these polymers or mixtures of polymers of formulas (I and It) or of their salts are added. Formula (I) denotes (I) and formula (II) denotes (II): HO--(--CH.sub.2 --CH.sub.2 --O).sub.r --(CHCH.sub.3 --CH.sub.2 --O).sub.s --(--CH.sub.2 --CH.sub.2 --O).sub.t --H and X<100% and Y>0%, R.sub.1 is --H or --CH.sub.3, R.sub.2 is --COOM, in which M may be H.sup.+ or a cation, in particular Na.sup.+, K.sup.+ or NH.sup.+.sub.4, R.sub.7 and R.sub.8 may be identical or different, being --COOM, --CONR.sub.5 R.sub.6, H, --OH or --COO(--CH.sub.2 --CH.sub.2 --O).sub.r --(CHCH.sub.3 --CH.sub.2 --O).sub.s --(--CH.sub.2 --CH.sub.2 --O).sub.t --H and R.sub.5 and R.sub.

Abstract: More reliable removal of sulfur oxides (SO.sub.x) from combustion effluents by in furnace injection is achieved by stabilizing slurries of calcium carbonate (limestone), calcium oxide (lime) and calcium hydroxide (hydrated lime) for extended periods of time and during in-furnace injection. The slurries are stabilized by a stabilization system comprising a generally hydrophobic surfactant having an HLB of less than about 8 and a more hydrophilic surfactant having an HLB of at least about 8, wherein the HLB values of the hydrophobic and the hydrophilic surfactants differ by at least about 3.

Abstract: Fluoridated particulates, especially external face surface-fluoridated particulates of the rare earth metal sesquisulfide pigments/colorants, advantageously encapsulated within a coating layer of at least one transparent oxide or hydrate thereof, e.g., silica, have improved chromatic properties and are well suited for the coloration/pigmentation of a wide variety of materials and substrates, for example paints, plastics, resins, varnishes, rubbers, ceramics, glazes, papers, inks, leathers, cosmetics, dyes, coatings, etc.

Abstract: More reliable removal of sulfur oxides (SO.sub.x) from combustion effluents by in furnace injection is achieved by stabilizing slurries of calcium carbonate (limestone), calcium oxide (lime) and calcium hydroxide (hydrated lime) for extended periods of time and during in-furnace injection. The slurries are stabilized by a stabilization system comprising a generally hydrophobic surfactant having an HLB of less than about 8 and a more hydrophilic surfactant having an HLB of at least about 8, wherein the HLB values of the hydrophobic and the hydrophilic surfactants differ by at least about 3.

Abstract: Subpigmentary titanium dioxide with decreased photoactivity is produced if known ions for increasing photostability in titanium dioxide pigments are not deposited on the surface of the subpigmentary particles, but instead are included intracrystallinely in the pigment particle (i.e., doped). In a preferred process for preparation of doped subpigmentary titanium dioxide particles, an acid solution containing the dopant is added in two stages to a suspension of subpigmentary titanium dioxide.

Abstract: The invention relates to methods for producing stabilized zirconium oxide powder suitable for pressing shaped elements and subsequent sintering to provide high-density ceramic materials. To this end, an aqueous solution of a zirconium salt containing an additive is converted into droplets. The droplets formed are solidified, by the action of ammonia, into gel particles which are then washed, dewatered dried and calcined.

Abstract: A stabilized ammonium polysulfide solution comprising an aqueous solution of ammonium polysulfide and a stabilizing amount of a water soluble, stabilizing compound that can be an azacyclic compound, a compound having the formula R--O--(C.sub.n H.sub.2n)NH.sub.2 or a compound having the formula (CH.sub.3).sub.2 NR.sub.1, the pH of the composition being from 7 to 14, the stabilized composition being useful in controlling the cyanide concentration in aqueous streams.

Abstract: Unique compositions based on at least one crystalline rare earth sesquisulfide, well suited for the coloration of a wide variety of substrates, e.g., cosmetics, plastics, paints and rubbers, contain a dopant amount of at least one alkali/alkaline earth metal, at least a fraction of which being included within the crystal lattice of such at least one rare earth sesquisulfide.

Abstract: The invention concerns the production of aluminum trihydrate crystal by the Bayer process, by digesting ground bauxite, filtering off the red mud, cooling the filtrate, and crystallizing out the dissolved aluminum hydroxide as gibbsite. Before and/or during the crystallization, polyglycerines of the general formula H--(OCH.sub.2 CHOH--CH.sub.2).sub.n --OH, where n is an integer equal to or greater than 3, are added.

Abstract: Ammonium nitrate is phase-stabilized against Phase IV.rarw..fwdarw.Phase III transition and the undesired volume changes associated with that phase change by including an effective amount of at least one metal dinitramide salt having the formula MX.sub.n wherein M is a metal cation, X is a dinitramide anion, and n is 1, 2 or 3. The phase-stabilized ammonium nitrate is useful in energetic applications such as solid propellants and explosives.

Abstract: Crystalline zirconium oxide powder with a BET surface of less than 30 m.sup.2 /g, preferably 10 to 20 m.sup.2 /g, a primary particle size of 0.1 to 0.5 .mu.m, a monoclinic crystal structure and, optionally, a content of Y.sub.2 O.sub.3 of 1 to 10% by weight and/or of 1 to 10% by wt. MgO.It is produced by adding an aqueous zirconium salt solution optionally containing yttrium ions and/or magnesium ions under agitation into a vessel which contains an aqueous base solution such as e.g. sodium hydroxide solution with a content of NaOH which corresponds to an excess of at least 0.5 mole/l NaOH. The mixture obtained in this manner is then treated hydrothermally at a temperature of 200.degree. to 400.degree. C., the product obtained is separated by filtration, washed chloride-free with water and dried at 100.degree. to 120.degree. C.The zirconium oxide powder can be used to produce sintered ceramics.

Abstract: A process for producing stable, high purity ferrate (VI) employing beta-ferric oxide (beta-Fe.sub.2 O.sub.3), and preferably monohydrated beta-ferric oxide (beta-Fe.sub.2 O.sub.3 .multidot.H.sub.2 O) as the iron source. An improved process for producing stable, high purity beta-ferric oxide is also disclosed. The process results in the efficient and effective productions of ferrate with high yields and small amounts of waste production. A large portion of the unused product stream can be recycled to the ferrate reactor for the production of additional ferrate.

Abstract: Crystalline zirconium oxide powder with a BET surface of less than 30 m.sup.2 /g, preferably 10 to 20 m.sup.2 /g, a primary particle size of 0.1 to 0.5 .mu.m, a monoclinic crystal structure and, optionally, a content of Y.sub.2 O.sub.3 of 1 to 10% by weight and/or of 1 to 10% by wt. MgO.It is produced by adding an aqueous zirconium salt solution optionally containing yttrium ions and/or magnesium ions under agitation into a vessel which contains an aqueous base solution such as e.g. sodium hydroxide solution with a content of NaOH which corresponds to an excess of at least 0.5 mole/l NaOH. The mixture obtained in this manner is then treated hydrothermally at a temperature of 200.degree. to 400.degree. C., the product obtained is separated by filtration, washed chloride-free with water and dried at 100.degree. to 120.degree. C.The zirconium oxide powder can be used to produce sintered ceramics.

Abstract: Aqueous thiocarbonate solutions are stabilized by the addition of base, sulfide and/or polysulfide, and the stability and safety of the more concentrated solutions containing 1 weight percent or more equivalent CS.sub.2 as a thiocarbonate are achieved as reflected by significant reduction of CS.sub.2 partial pressure in such solutions.

Abstract: A transparent, strong CsI alloy havign additions of monovalent iodides. Although the perferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy.

Abstract: A method of producing small diameter titanium carbide whiskers is disclosed. The method comprises supplying a source of materials comprised of titanium halide, hydrocarbon gas and nickel and reacting this material in the presence of a source of carbon monoxide to produce small diameter titanium carbide whiskers.

Abstract: Mixed zirconium and yttrium oxides (ZrO.sub.2 (Y.sub.2 O.sub.3)) with a yttrium content (evaluated as metal) from about 15 to about 21% by weight, as powders in cubic crystal form, are prepared by:mixing an aqueous solution of zirconium and yttrium carboxylates with an organic solvent in the form of a nitrile or alcohol;from said mixture, precipitating solid particles of the precursors of mixed zirconium and yttrium oxides by operating at a pH between 5 and 7 and at ambient or close to ambient temperature; andcalcining said precipitated solid particles at high temperature to directly transform them from the amorphous state to the cubic crystal form.The mixed zirconium and yttrium oxides obtained in this manner are suitable for use in the ceramics sector.

Abstract: A needle-like monoammine complex of zinc carbonate containing or not containing aluminum useful as a filler or a precursor of needle-like electroconductive zinc oxide, and a process for producing it which comprises steps of dissolving a zinc compound in a solution containing ammonium ion and carbonate ion in the presence or absence of aluminum compound and then lowering pH of the solution to precipitate zinc carbonate.

Abstract: A crystallized, stable histidine-hydrogen peroxide adduct intermolecular-bonded at 1:1 ratio is provided.

Abstract: Mixed oxides of zirconium and yttrium [ZrO.sub.2 (Y.sub.2 O.sub.3)], with an yttrium content (as computed as elemental metal) comprised within the range of from about 15 to about 21% by weight, as spherical particles with size comprised within the range of from 0.1 to 2 .mu.m, with an average size of the particles lower than 1 .mu.m, in the cubic crystal form, are obtained by:preparing a mixture by starting from an aqueous solution of zirconium and yttrium carboxylates; an organic solvent selected from the group consisting of nitriles or alcohols; and a non-ionic surfactant;causing solid colloidal particles of the precursor of mixed zirconium/yttrium oxides to precipitate from said mixture, by operating at a pH value comprised within the range of from 5 to 7, at room temperature or at temperature close to room temperature; andcalcining said precipitate of solid particles at a high temperature to cause said solid particles to be directly converted from the amorphous state into the cubic crystal form.

Abstract: Zirconium based granules are produced by the steps of forming an aqueous solution of a zirconium compound such as zirconium acetate, combining the aqueous solution with a phase stabilizer, and then heating the solution to evaporation thereby forming amorphous zirconium based granules.In an alternate embodiment, an alcohol solution of a zirconium compound such as zirconium propoxide in propanol is acidified and hydrolyzed with water. The partially or fully hydrolyzed zirconium complex is mixed with a phase stabilizer to form a homogeneous solution. The solution is then subjected to evaporation by heat to form amorphous zirconium based granules.Zirconia fibers are produced by making aqueous solutions of the amorphous zirconium based granules containing the phase stabilizer to the desired viscosity, fiberizing the solution, and finally converting the fibers under appropriate conditions.

Abstract: A method of modifying crystal structure of alumina trihydrate crystallizing from saturated Bayer liquors, which method includes the treatment of the saturated Bayer liquors with a crystal modifying amount of a polysaccharide, preferably a dextran.

Abstract: A process for economically producing tabular acicular gypsum crystals in a continuously stirred reactor is disclosed. The process involves establishing a steady state atmospheric pressure reaction zone of about 20% to about 25% by weight solids of gypsum crystals in water at a temperature of about 50.degree. C. to about 60.degree. C. with continuous mild agitation. Calcium sulfate hemihydrate is fed to the reaction zone at a rate to maintain a low level of supersaturation, and a suspension of gypsum crystals in water containing crystals of a mean particle length at least greater than 45 microns is withdrawn.

Abstract: A phase stabilized ammonium nitrate mixed crystal structure is produced by the addition of potassium fluoride. Thus the undesirable abrupt expansion and contraction of ammonium nitrate in the temperature range of use in rocket motor propellants and explosives (-55.degree. C. to .lambda..degree. C.) is eliminated. The mixture is made by the addition of between about 3% to 5% and preferably about 3.5% by weight potassium fluoride to the ammonium nitrate by a nonhazardous aqueous method.

Abstract: A process for producing a dawsonite with a short-prismatic, isometric crystal habit. The dawsonite can be produced without occupational medicine concerns and can be used as, among other things, a flame-retardant additive in plastics.

Abstract: A phase-stable, oxidizer-grade zinc diammine complex stabilized ammonium nitrate that retains its phase-stability, has a minimum hygroscopicity and cure interference, is prepared by dissolving an anhydrous zinc diammine complex, which may be either the sulfate, perchlorate or nitrate, in dry molten ammonium nitrate. The complex is best prepared in a separate step by melting a 3/1 molar mixture of ammonium nitrate with zinc oxide which produces the zinc diammine dinitrate complex contaminated with the water of the reaction. The melt is dried by driving off the water. First by simple boiling, and the final traces by means of purging with dry air or nitrogen gas. The ammonia lost in this drying operation is exactly replenished by purging with anhydrous ammonia gas. The sulfate complex is obtained by co-dissolving an essentially stoichiometric quantity of ammonium sulfate in either the melt of the complex or the bulk of the molten ammonium nitrate.

Abstract: In a process for producing phase-stabilized ammonium nitrate (AN), a diammine complex of Ni or Cu is incorporated into the AN lattice, in which the diammine complex is produced in a solid-state reaction of AN and metal oxide at 110.degree. to 170.degree. C. and in a proportion of up to 10% is either mixed with further AN and melted, homogenized and subsequently transferred into the solid state, or mixed with further AN is incorporated into the AN lattice at between 80.degree. and 170.degree. C. in a solid-state reaction.

Abstract: Zirconium based granules are produced by the steps of forming an aqueous solution of a zirconium compound such as zirconium acetate, combining the aqueous solution with a phase stabilizer, and then heating the solution to evaporation thereby forming amorphous zirconium based granules.In an alternate embodiment, an alcohol solution of a zirconium compound such as zirconium propoxide in propanol is acidified and hydrolyzed with water. The partially or fully hydrolyzed zirconium complex is mixed with a phase stabilizer to form a homogeneous solution. The solution is then subjected to evaporation by heat to form amorphous zirconium based granules.Zirconia fibers are produced by making aqueous solutions of the amorphous zirconium based granules containing the phase stabilizer to the desired viscosity, fiberizing the solution, and finally converting the fibers under appropriate conditions.

Abstract: For the preparation of dicalcium phosphate dihydrate stabilized with dimagnesium phosphate trihydrate and sodium pyrophosphate, an aqueous suspension of calcium carbonate is introduced into a reactor and recirculated by pumping through a high-speed mixer at 3,500 to 8,000 rpm which is in flow connection with the lower and upper portion of the reactor. Into the mixer an amount of phosphoric acid is introduced which is at least sufficient for the quantitative formation of dicalcium phosphate dihydrate and then an oxygen-containing magnesium compound is introduced into the reactor. Finally, lime milk is metered into the reactor up to a maximum pH of 6.9, before the sodium pyrophosphate is added to the reactor. The resulting suspension which has a stabilized dicalcium phosphate dihydrate content of 20 to 33% by weight is spray-dried.

Abstract: Crystalline zirconium oxide powder with a BET surface of less than 30 m.sup.2 /g, preferably 10 to 20 m.sup.2 /g, a primary particle size of 0.1 to 0.5 .mu.m, a monoclinic crystal structure and, optionally, a content of Y.sub.2 O.sub.3 of 1 to 10% by weight and/or of 1 to 10 % by wt. MgO.It is produced by adding an aqueous zirconium salt solution optionally containing yttrium ions and/or magnesium ions under agitation into a vessel which contains an aqueous base solution such as e.g. sodium hydroxide solution with a content of NaOH which corresponds to an excess of at least 0.5 mole/1 NaOH. The mixture obtained in this manner is then treated hydrothermally at a temperature of 200.degree. to 400.degree. C., the product obtained is separated by filtration, washed chloride-free with water and dried at 100.degree. to 200.degree. C.The zirconium oxide power can be used to produce sintered ceramics.

Abstract: A wet process production of phosphoric acid in which phosphate rock is digested, whereby phosphoric acid is released and calcium sulfate crystals are formed, employs a polymeric crystal modifier in the digestion stage of the process to improve the separation of the raw phosphoric acid product from the calcium sulfate crystals and to increase the concentration of phosphoric acid in the raw phosphoric acid product.