Abstract: Pellet-shaped calcium hydroxide forming part of the mixture of flux and ores in electrothermal calcium carbide furnaces is calcined. The pellets are made by granulating or briquetting moist calcium hydroxide, delivered to a sintering grate and conveyed thereon through a heating zone, wherein high temperatures are produced by the combustion of gas, above the grate, and wherein the combustion gas is exhausted, below the grate. The calcium hydroxide pellets are more especially placed on to the grate, covered with a layer of broken limestone and the undried pellets are directly conveyed through the heating zone, in an apparatus for carrying out the process.

Abstract: An agitated reactor is described for use in the continuous conversion of liquid white phosphorus to red phosphorus. Critical relations of the reactor vessel shape and measurements and the agitator measurements are described for preventing build-up of red phosphorus solids in the reactor as the continuous conversion proceeds.

Abstract: Sulfur dioxide and nitrogen oxides can be removed from effluent gases with increased efficiency by blowing contaminated air present in the irradiation room into a stream of the effluent gases before the mixture is delivered to a reaction chamber to be irradiated with an ionizing radiation or ultraviolet light. This provides also a convenient process for purifying the contaminated air containing nitrogen oxides and ozone before release into the atmosphere. Thus, simultaneous purification of industrial effluent gases and contaminated air is advantageously carried out.

Abstract: Process for purifying trioctyl phosphate containing emulsifier impurities comprising alkali metal salts of dioctyl phosphoric acid and monooctyl phosphoric acid by contacting the trioctyl phosphate with a mineral acid to neutralize the emulsifier impurities and to provide a two-phase system having an organic phase and an aqueous phase wherein the pH value of the aqueous phase is below 3.0, separating the organic phase from the aqueous phase, dehydrating the organic phase, and removing neutralized impurities by absorption on an absorbent material leaving a substantially pure trioctyl phosphate having an interfacial tension of about 18 to about 24 dynes/cm. The purified trioctyl phosphate has exceptional utility as a solvent in the anthraquinone process for producing hydrogen peroxide.

Abstract: A method is provided for extracting silver from a silver sulfate-bearing substance, such as oxide materials, metal or metal sulfate mixtures containing silver sulfate which comprises subjecting said substance to aqueous leaching to remove soluble salts therefrom and leave a residue, taking the residue containing silver sulfate and other insoluble materials, such as insoluble salts, and forming a slurry with an aqueous solution of a metal sulfate, such as calcium nitrate, the amount of calcium nitrate being at least sufficient to effect metathetical exchange with the silver sulfate and form a silver nitrate solution containing substantially the silver originally present in the silver-sulfate bearing substance, and separating the silver nitrate solution from the residue remaining, and then purifying said solution, the silver being thereafter recovered from the silver nitrate solution by hydrolytic precipitation, electrowinning or other suitable means.

Abstract: A method of disposing of silica dust recovered from the smoke of metallurgical furnaces by producing aluminum fluoride therefrom for use in electrolytic melting furnaces is disclosed. Fluorspar and the precipitated amorphous silicon dioxide are treated with steam at elevated temperatures whereby hydrogen fluoride-containing gases are produced and then these gases are passed through a layer of aluminum oxide. Part of the gaseous hydrogen fluoride will then react with the alumina to form aluminum fluoride and part of it will be adsorbed in the alumina whereby an intimate mixture of alumina and fluorine is obtained which is useful in electrolytic furnaces.

Abstract: Phosphoric acid is purified. To this end, it is dissolved in an organic solvent completely miscible with water. More particularly, the phosphoric acid is mixed with a solvent having a boiling point higher than that of water or higher than that of the resulting azeotrope; the resulting solution is heated to temperatures between the boiling point of water or the azeotrope and that of the solvent for as long a period as necessary to distillatively free the solution from the bulk of uncombined water therein; and the phosphoric acid solution is separated from residue.

Abstract: Zinc bearing solutions are subjected to cementation in at least one fluidized bed of zinc particles which are simultaneously subjected to transverse agitation to remove impurities precipitated on the particles.

Abstract: A system for improving the absorption of gaseous SO.sub.2 contained in flue gases by contact with an absorbing slurry, separating the unreacted solids from the reacted solids in the slurry product of the absorption in an inertial separator and recycling the unreacted solid containing slurry to the SO.sub.2 absorption system.

Abstract: Processes for the preparation of high-purity free-flowing crystalline powder phosphorus pentachloride which processes comprise reacting phosphorus trichloride with a deficit of chlorine, cooling the reaction mixture to form a crystalline mass containing the pentachloride, and recovering and/or purifying the pentachloride.

Abstract: High strength graphite is manufactured from a mixture of a particulate filler prepared by treating a particulate carbon precursor at a temperature in the range of about 400.degree. to 1000.degree. C., an organic carbonizable binder, and green carbonizable fibers in a concentration of not more than 2 weight per cent of the filler. The use of the relatively small quantity of green fibers provides a substantial increase in the flexural strength of the graphite with only a relatively negligible increase in the modulus of elasticity.

Abstract: The present invention relates to an improved method for the manufacture of potassium phosphates. More specifically the present invention provides a process for the manufacture of monopotassium phosphate, KH.sub.2 PO.sub.4, from potassium bearing brines.

Abstract: A process for purifying wet process phosphoric acid to a food grade phosphoric acid by a sequence of steps including extraction, partial neutralization, dilution with water, contact with activated carbon, neutralization to a pH of from about 5 to about 9, contact with activated carbon, contact with an insoluble alkaline earth metal phosphate salt, reconversion to a purified food grade phosphoric acid, and recovery of the product acid.

Abstract: A process for the manufacture of alkali metal polyphosphates having a predetermined crystalline form, in which a mixture of alkali metal orthophosphates having a molar ratio of alkali metal oxide to phosphoric anhydride between 1 and 2 is first granulated, the resulting granules are dried and then are subjected to thermal treatment in the presence of aqueous vapor.

Abstract: A method for purifying a crude or wet process phosphoric acid to a technical grade phosphoric acid comprising a sequence of steps including diluting the crude phosphoric acid, contacting the crude phosphoric acid with activated carbon, neutralization of the acid to a phosphate salt solution, contacting the phosphate salt solution with activated carbon and reconversion to a purified technical grade phosphoric acid.

Abstract: A process for converting wet process phosphoric acid to food grade alkali metal phosphates by a sequence of steps including extraction of the wet process acid, partial neutralization, dilution with water, contact with activated carbon, neutralization to a pH of from about 5 to about 9, contact with activated carbon, contact with insoluble alkaline earth metal phosphate salts and recovery of the dissolved alkali metal phosphate product in solution.

Abstract: A method is provided for removing silver from aqueous systems contaminated therewith with 2-mercaptopyridine-1-oxide and for recovering the 2-mercaptopyridine-1-oxide.

Abstract: A process for recovering pure selenium from metal substrates having a selenium coating thereon without impairment of the substrate for reuse which comprises substantially converting the selenium in said coating to a water-soluble selenocyanate by immersing the coated substrate in an aqueous solution of an alkali metal cyanide, removing the substrate from the resultant solution, treating the resultant solution with an acid to precipitate the selenium from the remaining liquid.

Abstract: A method of effectively removing nitrogen oxides which are entrained in a gas, wherein a nitrogen oxide-containing gas is brought into contact with an aqueous solution which contains at least one ferrous salt and one sulfurous acid alkali salt to absorb the nitrogen oxides in the solution in the form of imidodisulfonic acid alkali salt, hydrolyzing the imidodisulfonic acid alkali salt to obtain a hydrolyzate-containing solution, and adding nitrous acid, nitrous acid anhydride, or nitrite to the hydrolyzate-containing solution to generate nitrogen.

Abstract: A water immiscible amine-solvent system, preferably a solution of a water immiscible amine in mineral spirit solvent, is used to extract phosphate values from crude aqueous phosphoric acid solutions leaving behind impurities, e.g., calcium, magnesium, iron and aluminum. Phosphoric acid of water white quality may then be produced and removed from the amine-solvent organic phase by contacting the amine-solvent containing the extracted phosphate values with sulfur dioxide and water substantially in the absence of oxygen, the amount of water employed determining the concentration of phosphoric acid produced, thermally stripping the sulfur dioxide from the amine-solvent system substantially in the absence of oxygen in order to recycle both the amine-solvent system and sulfur dioxide.