Abstract: A dental pulp capping composition can comprise a particulate base material which is non-toxic, and capable of forming a structural capping matrix; and a particulate setting material which is non-toxic, water-soluble, biocompatible, and capable of setting the composition. Optional growth factors can also be introduced into the composition to facilitate dental tissue repair. A complimentary method of restoring damaged tooth features can comprise removing diseased and/or damaged portions of the tooth to expose a prepared tooth region. Water can be added to the dental pulp capping composition to form a workable coherent paste. The workable coherent paste can be introduced into the prepared tooth region. The workable coherent paste can then be shaped within the prepared tooth region and then set to form a rigid biomimetic structure within the prepared tooth region.

Abstract: A method and device for producing a solution of polyphosphoric acid from a feed solution P0 by the wet method is provided. An enriched phosphoric acid solution optionally mixed with a direct feed solution is pulverised in a flame of a combustion chamber in order to form the polyphosphoric acid solution. The combustion gases from the combustion chamber are placed in contact with the feed solution in a gas-acid contactor in order to increase the temperature and the P2O5 concentration thereof and thus to form an enriched phosphoric acid solution. A portion of the enriched phosphoric acid solution is conveyed with a flow rate of Qp into the combustion chamber in order to be pulverised in the flame. The rest of the enriched phosphoric acid solution is conveyed into a recirculation loop in order to be reinjected into the gas-acid contactor with a flow rate of Q2. The ratio of Qp/(Qp+Q2) is controlled with a predefined value.

Abstract: A method and device for producing polyphosphoric acid burns a fuel in combustion air in a combustion chamber, sprays a spray fluid comprising substantially pure orthophosphoric acid and undertakes polymerization-condensation of the pure orthophosphoric acid. A polyphosphoric acid in the form of an acid mist accompanied by formation of gases which mix with combustion gases resulting from burning of the fuel is formed to reach a predetermined temperature, wherein the mixture causes sudden lowering of combustion gas temperature. The acid mix is separated from the gas mixture and the polyphosphoric acid is collected at a bottom of the combustion chamber and the gas mixture is outputted via a lower part of the combustion chamber separate from the collection of polyphosphoric acid.

Abstract: Disclosed is an apparatus for preparing phosphoric acid from a fume exiting the kiln in a kiln phosphoric acid process, the apparatus comprises a hydration tower and an acid solution cyclical spraying system, a fume inlet of the fume exiting the kiln is disposed at a lower portion of the hydration tower, a fume outlet after hydration and absorption is disposed at the top, a spraying device is disposed in a cavity of the hydration tower above the fume inlet, a liquid inlet of the acid solution cyclical spraying system is disposed on a bottom of the hydration tower, a liquid outlet of the acid solution cyclical spraying system is connected to a liquid intake pipe of the spraying device. The present invention has the advantages of simple structure, reasonable layout, strong adaptability, high raw material utilization rate, reduced contaminant emissions, and high recovery rate of phosphoric acid etc.

Abstract: A method and device for producing polyphosphoric acid burns a fuel in combustion air in a combustion chamber, sprays a spray fluid comprising substantially pure orthophosphoric acid and undertakes polymerization-condensation of the pure orthophosphoric acid. A polyphosphoric acid in the form of an acid mist accompanied by formation of gases which mix with combustion gases resulting from burning of the fuel is formed to reach a predetermined temperature, wherein the mixture causes sudden lowering of combustion gas temperature. The acid mix is separated from the gas mixture and the polyphosphoric acid is collected at a bottom of the combustion chamber and the gas mixture is outputted via a lower part of the combustion chamber separate from the collection of polyphosphoric acid.

Abstract: Polyphosphoric acid compositions having a reduced viscosity compared to neat polyphosphoric acid. The viscosity of the polyphosphoric acid is reduced by combining the polyphosphoric acid with an additive that reduces the viscosity of the polyphosphoric acid composition. In one embodiment, additives that can cause solvation and/or partial neutralization of the polyphosphoric acid without the addition of water may be used. The reduced viscosity polyphosphoric acid may be used, for example, as an additive in asphalts used in road pavements.

Abstract: This disclosure relates to the use of phosphoric acid. In particular, this disclosure relates to the use of phosphoric acid for treating cardiovascular disorders such as atherosclerosis. This disclosure further relates to compositions, kits, methods, and the like.

Abstract: Provided is a method for preparing high-purity elemental phosphorus capable of simultaneously reducing both arsenic and antimony from crude white phosphorus containing a great amount of arsenic and antimony as impurities. Provided is a method for preparing high-purity elemental phosphorus, the method including bringing liquid crude white phosphorus into contact with an iodic acid-containing compound selected from iodic acid and iodates in an aqueous solvent in the presence of a chelating agent, wherein the chelating agent is selected from polyvalent carboxylic acids, polyvalent carboxylates, phosphonic acid and phosphonates.

Abstract: Activated carbon is rendered more thermally stable by exposure to a non-halogenated additive, and optionally to a halogen and/or a halogen-containing compound. Such treated carbon is suitable for use in mitigating the content of hazardous substances in flue gases, especially flue gases having a temperature within the range of from about 100° C. to about 420° C.

Abstract: The invention provides a method for extracting a Staphylococcus aureus antigen which comprises using an extraction reagent with a pH of no higher than 5.0, containing one or more acids selected from among hydrochloric acid, acetic acid, citric acid, phosphoric acid, sulfuric acid and nitric acid, to extract a Staphylococcus aureus antigen comprising a methicillin-resistant Staphylococcus aureus antigen and/or a methicillin-sensitive Staphylococcus aureus antigen, from Staphylococcus aureus in a specimen. The invention further provides a method for assessing Staphylococcus aureus.

Abstract: A method for producing phosphates and/or compounds containing phosphates is provided, in particular alkaline-earth phosphates, alkaline-earth silicophosphates, and alkaline-earth oxides, comprising the following steps: (a) heating bones and/or fish bones or a composition of said components in a pyrolysis process in the absence of oxygen and under reductive conditions at temperatures between 500 and 1100° C., wherein among other things high-energy gases, vapors, and carbon are produced, (b) subsequently combusting the carbon produced in step (a) under oxidative conditions in an oxidation step, wherein an inorganic radical of alkaline-earth carbonates, alkaline-earth oxides, and alkaline-earth phosphates is produced.

Abstract: Methods for preventing or reducing the formation of scale in a wet-process phosphoric acid production process by intermixing a scale inhibiting reagent at one or more step of the phosphoric acid production process in an amount sufficient to prevent or reduce scale are provided.

Abstract: The present invention relates to a method for production of calcium compounds having very low content of phosphorus and boron from an impure calcium chloride, solution containing phosphorus and boron, which method comprises the following steps: a) addition of a FeCl3-solution to the calcium chloride solution, b) adjusting the pH of the solution by addition of a base to between 3 and 9.5 for precipitation of iron hydroxide, iron phosphate and boron compounds, c) removal of the solid precipitate from the solution in step b) obtaining a purified calcium chloride solution, d) precipitation of a calcium compound from the solution from step c), and e) separation of the calcium compound from the solution in step d).

Abstract: A method for minimizing the addition of water to a phosphoric acid production process is described. The method uses phosphoric acid to make down a flocculant that is added to the process in order to promote filtration or clarification of crude phosphoric acid. Preferably, the phosphoric acid is a crude, clarified phosphoric acid that is recycled from the phosphoric acid production process itself.

Abstract: Provided is a method for preparing high-purity elemental phosphorus capable of simultaneously reducing both arsenic and antimony from crude white phosphorus containing a great amount of arsenic and antimony as impurities. Provided is a method for preparing high-purity elemental phosphorus, the method including bringing liquid crude white phosphorus into contact with an iodic acid-containing compound selected from iodic acid and iodates in an aqueous solvent in the presence of a chelating agent, wherein the chelating agent is selected from polyvalent carboxylic acids, polyvalent carboxylates, phosphonic acid and phosphonates.

Abstract: The invention relates to a method for the purification or recovery of orthophosphoric acid rich streams by suspension-based melt crystallization. The orthophosphoric acid is crystallized as the hemi-hydrate form and subsequent separation of such crystals in a wash-column produce a high purity acid/water solution that has been depleted of most of the metals and impurities other than water, thereby separating an orthophosphoric acid rich feed liquor into an ultra-pure orthophosphoric acid hemi-hydrate and a mother liquor containing almost all impurities originally present in the feed. The orthophosphoric acid rich feed liquor typically contains no more than 15 wt % water and 1 wt % other impurities. Individual metal ion composition in the purified orthophosphoric acid product is in the range of 100 to 1000 ppb (parts per billion= 1/1000 ppm) of each metal ion. The metal ion composition of the resulting purified product is thus typically below the detection limit of typical analysis equipment.

Abstract: Aqueous leachant compositions and processes for using the same comprising: (a) providing a metal-containing compound; and (b) subjecting the metal-containing compound to an acid digestion comprising contacting the metal-containing compound with an aqueous leachant; wherein the aqueous leachant comprises a mixture selected from the group consisting of: (i) sulfuric acid and one or more alkanesulfonic acids having alkane moieties selected from the group consisting of propyl, ethyl and methyl groups, at a weight ratio of alkanesulfonic acid to sulfuric acid of 1:1000 to 1:1; (ii) sulfuric acid and one or more salts of alkanesulfonic acids having alkane moieties selected from the group consisting of propyl, ethyl and methyl groups, at a weight ratio of salt of alkanesulfonic acid to sulfuric acid of 1:9 to 1:99.

Abstract: A phosphorous pentoxide producing method includes forming a kiln bed using feed agglomerates with a calcium-to-silica mole ratio of from 0.5 to 1.0 and maintaining a bed temperature at or above 1260° C. along a portion of the bed length without exceeding 1380° C. along the entire bed length. Less than 10% of the agglomerates' phosphate input to the kiln remains in the kiln residue as phosphate. Another method includes maintaining a bed temperature at or above 1180° C. along a portion of the bed length and establishing a bed surface-to-volume ratio multiplied by a time for bed heat up to 1180° C. of less than 50 minutes-ft2/ft3.

Abstract: By using phosphorus compounds, diesters of dicarbonic acid may be stabilized against thermal and chemical decomposition over a relatively long period. Mixtures of diesters of dicarbonic acid and phosphorus compounds are outstandingly suitable for preserving foods.

Abstract: The invention relates to a repulpable adhesive comprising orthophosphoric acid, to adhesive tapes comprising at least one layer of such an adhesive, and to the use of adhesive tapes of this kind.

Abstract: A process for treating organic material, separating calcium and recovering phosphorus and to utilization of the obtained products and their use as a soil conditioner and a fertilizer as well as for providing carbon dioxide traps in gas cleaning. In the process, organic ingredients are separated from calcium-phosphate-containing ingredients, the calcium-phosphate-containing ingredients are dissolved in an acid-containing solution and/or the calcium is precipitated as a salt corresponding to the acid, and optionally phosphoric acid formed from a phosphate ion is separated. The invention also relates to a calcium-carbonate-containing product and a phosphoric-acid containing product, which are prepared by the process of the invention.

Abstract: High purity phosphoric acid having an Sb content of 200 ppb or less and a sulfide ion content of 200 ppb or less as impurity contents on a 85 weight percent H3PO4 basis. The high purity phosphoric acid is useful as an etching solution for semiconductor devices having a silicon nitride film, an etching solution for liquid crystal display panels having an alumina film, a metallic aluminum etching solution, an alumina etching solution for ceramics, a raw material of phosphate glass for optical fiber, a food additive, and so forth. A metallic material having low capability of forming a lithium compound penetrates through the whole thickness of the active material layer 5.

Abstract: The invention relates to a method for the purification or recovery of orthophosphoric acid rich streams by suspension-based melt crystallization. The orthophosphoric acid is crystallized as the hemi-hydrate form and subsequent separation of such crystals in a wash-column produce a high purity acid/water solution that has been depleted of most of the metals and impurities other than water, thereby separating an orthophosphoric acid rich feed liquor into an ultra-pure orthophosphoric acid hemi-hydrate and a mother liquor containing almost all impurities originally present in the feed. The orthophosphoric acid rich feed liquor typically contains no more than 15 wt % water and 1 wt % other impurities. Individual metal ion composition in the purified orthophosphoric acid product is in the range of 100 to 1000 ppb (parts per billion= 1/1000 ppm) of each metal ion. The metal ion composition of the resulting purified product is thus typically below the detection limit of typical analysis equipment.

Abstract: A phosphorous pentoxide producing method includes forming a kiln bed using feed agglomerates with a calcium-to-silica mole ratio of less than 1.0 and maintaining a bed temperature at or above 1180° C. along at least 50% of the bed length without exceeding 1380° C. along the entire bed length. Less than 10% of the agglomerates' phosphate input to the kiln remains in the kiln residue as phosphate. Another method includes maintaining a bed temperature at or above 1180° C. along a portion of the bed length and establishing a bed surface-to-volume ratio multiplied by a time for bed heat up to 1180° C. of less than 50 minutes-ft2/ft3.

Abstract: A process for purifying phosphoric acid includes removing volatile components from phosphoric acid rich in impurities to form a crude phosphoric acid liquid substantially free of volatile components; heating the crude phosphoric acid liquid to a temperature above 250° C. in order to decompose phosphoric acid in the crude phosphoric acid liquid and generate gaseous phosphoric anhydride; and introducing the gaseous phosphoric anhydride into water or a dilute phosphoric acid aqueous solution in order to hydrate the gaseous phosphoric anhydride to form phosphoric acid.

Abstract: In a process of eluting phosphorus from sludge into a liquid phase and recovering the phosphorus efficiently, cell walls of microorganisms in the sludge are ruptured by a process selected from crushing sludge (for example, treating with an ultrasonic wave homogenizer), treating with ozone, and treating with heat. Then the liquid phase is treated with alkali, thereby eluting the phosphorus into a liquid phase efficiently in a short time. By coagulating and precipitating, the phosphorus eluted into the liquid phase is recovered.

Abstract: The present invention is a process for upgrading feedstock prepared from raw phosphate ore. Phosphorus sludge is burned to produce impure phosphoric acid and the acid is combined with beneficiated phosphate ore to prepare anhydrous monocalcium phosphate. Feedstock prepared from raw phosphate ore is blended with anhydrous monocalcium phosphate to upgrade the feedstock.

Abstract: The present invention provides a purification method of phosphoric acid, which includes bringing phosphoric acid containing arsenic into contact with hydrogen halide, thereby to remove the arsenic from the phosphoric acid, and a purification method of phosphoric acid, which includes bringing phosphoric acid containing arsenic into contact with hydrogen halide in the presence of a compound capable of generating hydrogen halide under acidic conditions. According to the method for purifying phosphoric acid of the present invention, a completely new method for removing arsenic in phosphoric acid is provided, which does not require a filtration or deaeration step or shows a great amount of residual sodium, unlike a sulfide coagulation method. This method is applicable to high concentration phosphoric acid, particularly polyphosphoric acid, and can be practiced at a low cost.

Abstract: The invention relates to a process for producing simultaneously food-grade and fodder-grade phosphoric acid by crystallizing phosphoric acid hemihydrate, H3PO4×0.5H2O, from a prepurified feed acid, which is purified and crystallized with the help of the following steps, a) after the step of froth-flotation of phosphate concentrate, the concentrate is directed to a strongly magnetic separation step in order to decrease the Mg ion amount, b) the phosphate concentrate is leached in a mixture of sulfuric acid and phosphoric acid according to the wet process, the precipitated SO4 and As ions are removed, and a silicon source is added in order to adjust the F/Si molar ratio to <6, c) the phosphoric acid is concentrated, the solids precipitate is removed, and the F ions are evaporated, d) the feed acid obtained from step c, having a concentration of >58% P2O5, solids concentration of <0.05%, Mg ion concentration of <1.

Abstract: The present invention provides a process for preparing hexafluorophosphoric acid complexed with about 1 to 3.3 molecules of water which are stable at temperatures below 20° C. and the compositions prepared thereby.

Abstract: An improved method for making polyphosphoric acid from phosphoric acid includes the steps of introducing a first phosphoric acid feed stream into the top end of a packed column, introducing a second phosphoric acid feed stream into a stream of hot air to form a stream of hot air and acid, introducing the stream of hot air and acid into the bottom end of the column, and polymerizing phosphoric acid of the first and second phosphoric acid feed streams to make polyphosphoric acid. By-product phosphoric acids containing organic contaminants may be substituted for all or part of the phosphoric acid stream being introduced into the bottom end of the column to allow recovery of the phosphorus values of the by-product phosphoric acids.

Abstract: The present invention provides a method, and an apparatus, for forming a prescribed concentration of a substance in a mixture with a fluid, from a comparatively dilute mixture. The mixture is most preferably a solution of a solute in a solvent. The following summary and description generally discuss the invention in terms of a particularly preferred solution and a preferred use for that solution; however, in its broadest embodiments, the invention encompasses both the use for other solutions, and the use for a suspension of a solid substance in a fluid to form a mixture (which can also be referred to as a slurry). The invention provides for significant economic, safety and qualify benefits over conventional evaporative systems.

Abstract: Catalysts that are useful for hydrocarbon conversions and oxygenate conversions, and a method for making such catalysts. The method for making the catalysts comprises forming a mixture comprising molecular sieves comprising pores having a diameter smaller than about 10 Angstroms, an inorganic sol, and an external phosphorus source, and drying the mixture.

Abstract: Setting times of calcium phosphate cement compositions are enhanced by the addition of phosphate or carbonate lubricant compositions. Methods for preparing the cement compositions are provided.

Abstract: Setting times of calcium phosphate cement compositions are enhanced by the addition of phosphate or carbonate lubricant compositions. Methods for preparing the cement compositions are provided.

Abstract: Methods and compositions are provided for preparing storage stable partially neutralized acid compositions. The partially neutralized acid compositions are amenable to prolonged periods of storage. Following storage, the acids can be neutralized with a calcium neutralizing source and combined with a lubricant to form a rapidly setting calcium phosphate mineral suitable for a variety of purposes, e.g. bone replacement.

Abstract: Aqueous phosphorus wastes from the electric furnace production of phosphors and containing heavy metal bearing particulates are treated with lime whereby the phosphorus is converted into useful phosphorus compounds and the heavy metals rendered sufficiently non-leachable to permit their release into the environment. The treatment is conducted above about 60.degree. C. at a pH of between about 11.0 to 12.5.

Abstract: Disclosed is a method of making phosphorous acid or hypophosphorous acid by reacting hydrogen chloride with a sodium phosphite or a sodium hypophosphite, respectively, in the presence of water to precipitate sodium chloride crystals and form the acid. The acid is separated from the sodium chloride crystals and can be passed through an anion exchange column that is preferably loaded with phosphite or hypophosphite ions, respectively, to remove residual chloride ions.

Abstract: Setting times of calcium phosphate cement compositions are enhanced by the addition of phosphate or carbonate lubricant compositions. Methods for preparing the cement compositions are provided.

Abstract: A process for oxidizing aqueous elemental phosphorus containing residues (sludges) to produce orthophosphate containing slurries suitable for subsequent reaction with ammonia to produce nitrogen- and phosphorus-containing fertilizer products. It comprises reacting aqueous elemental phosphorus containing residues with certain special mixtures of concentrated nitric acid and sulfuric acid to effect the conversion of the elemental phosphorus content of the residues into mostly orthophosphoric acid and very little orthophosphorous acid with the relative ratios of orthophosphoric acid to orthophosphorous acid produced being dependent upon the weight ratio H.sub.2 SO.sub.4 :HNO.sub.3 employed in the processing. The reaction is conducted at the boiling point of the resulting aqueous reaction medium.

Abstract: There is disclosed a process for the controlled hydrolysis of phosphorus trichloride which avoids the formation of lower oxides of phosphorus, phophines and diphosphines wherein phosphorus pentachloride is added to the phosphorus trichloride from about 20 to about 90 percent by weight of the phosphorus trichloride and then water in the form of finely divided droplets is added over the surface of the phosphorus trichloride while the temperature is controlled to below about 80.degree. C.

Abstract: Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorous preferably in a wet scrubber. The addition of yellow phosphorous in the system induces the production of O.sub.3 which subsequently oxidizes NO to NO.sub.2. The resulting NO.sub.2 dissolves readily and can be reduced to form ammonium ions by dissolved SO.sub.2 under appropriate conditions. In a 20 acfm system, yellow phosphorous is oxidized to yield P.sub.2 O.sub.5 which picks up water to form H.sub.3 PO.sub.4 mists and can be collected as a valuable product. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm.

Abstract: Phosphorous acid is formed by gaseous phase oxidation of phosphorus with water vapour to form predominantly P.sub.2 O.sub.3 and dissolving the P.sub.2 O.sub.3 so-formed in water. The P.sub.2 O.sub.3 also can be recovered as the product by quenching the P.sub.2 O.sub.3 to a stable temperature using an inert cooling medium rather than water. Oxygen also may be used in conjunction with the water vapour. Sufficiently rapid quenching of reaction products may result in the formation of red amorphous phosphorus from unreacted phosphorus.

Abstract: In the production of suspension fertilizers the addition of an additive comprising lignosulfonate to the wet-process acid prior to the ammoniation step prevents severe thickening of the suspension during its formation, which severe thickening is normally associated with in situ mass crystallization of monoammonium phosphate and which mass crystallization results in (1) the total prevention of further ammoniation of said acid or, at the very least, extremely slow further ammoniation thereof, and/or (2) excessive ammonia losses. Also, addition of said lignosulfonate to the acid prevents the formation of metallic impurity gel-like compounds which cause extremely high viscosities, nonpourability, and complete destruction of fluidity.

Abstract: New processes and equipment are disclosed for producing elemental phosphorus and thermal phosphoric acid. Benefits are listed below.1. Phosphorus-containing solids are recycled to smelting furnaces thus eliminating hazardous waste generation.2. Phosphorus furnace feedstock is upgraded and this permits unbeneficiated phosphate ore to be smelted.3. Energy is conserved during manufacture of elemental phosphorus and phosphoric acid.4. Electric energy is produced by cogeneration.5. Fluorine in phosphate ore is recovered as ammonium fluoride.6. Phosphorus-containing liquids are used as feedstock for production of suspension fertilizers.Benefits are achieved by agglomerating phosphate ore with monocalcium phosphate binder by a method which upgrades the ore. Phosphorus-containing solids are fluidized and burned to form an impure phosphoric acid mixture which is reacted with small sized phosphate ore to form monocalcium phosphate binder.

Abstract: A process for treating a pyrophoric P.sub.4 -containing material to convert it to a substantially non-pyrophoric P.sub.2 O.sub.5 material is described. The process comprises supplying streams of fluid P.sub.4 -containing material and an oxygen-containing gas to a reactor filled with water. The P.sub.4 -containing material and the oxygen and the oxygen-containing gas react with one another after both have entered the aqueous medium within the reactor to thereby form the desired P.sub.2 O.sub.5 material.

Abstract: The purification of phosphorous acid which is formed in halogenations of hydrocarbon derivatives using phosphorus trihalides is carried out in the context of preparing phosphorous acid in a reaction zone by reacting a mixture of phosphorus trichloride and water which has been finely divided by means of steam at temperatures between 150.degree. and 200.degree. C. in the gas phase. In this process, the liquid reaction product drains into a concentrating evaporation zone which has a downstream first separation zone. Inert gas is introduced to the lower part of the first separation zone. A melt is withdrawn from the first separation zone into a crystallizing zone. The waste gases from the reaction zone are treated with a washing liquid in a second separation zone before being passed into the atmosphere. The washing liquid used is an aqueous solution of never-purified phosphorous acid, which can have been prepurified by hydrolysis and stripping.

Abstract: Crude phosphoric acid is made by subjecting crude phosphate ore containing sulfide to processing treatment with a mineral acid in a closed system comprised of a processing reactor, a filtering zone and an off-gas scrubbing zone. To this end, a soluble compound of a metal forming difficultly soluble sulfides in the respective acid medium is added either(A) during the processing operation the phosphate ore is subjected to or(B) during the scrubbing operation the off-gas is subjected toand the resulting sulfide precipitate is filtered off in case (A) together with further matter precipitated during the processing operation and, in case (B) separated from the scrubbing liquid.

Abstract: Heat is recovered from the phosphorus combustion chamber of a furnace phosphoric acid plant by placing in the combustion chamber a heat exchange surface having a protective meta acid coating thereon. Pressurized water can be used as a heat exchange fluid.

Abstract: Aqueous phorphoric acid solutions are produced by contacting an elemental phosphorus-containing material with an oxygen-containing gas, while both are finely divided and well mixed together in a reactor vessel, while the phosphorus-containing material is otherwise protected from direct contact with oxygen in the atmosphere by being blanketed with a protective aqueous layer, and removing and recovering the heat generated in the reactor vessel (e.g., by means of a heat exchanger) due to the contact between the oxygen in the oxygen-containing gas and the elemental phosphorus in the elemental phosphorus-containing material. The technique is useful for the production of phosphoric acid from substantially pure elemental phosphrous.