Abstract: Wet process phosphoric acid is purified by extraction with a hexanone of pentanone to form an organic extract, containing phosphoric acid, from which the acid content is recovered by treatment with water or aqueous phosphoric acid in 2 or more portions to give 2 or more purified acids, the recovery to give the last purified acid being in more than 1 countercurrent stage.

Abstract: The invention relates to a process for making red phosphorus by subjecting molten yellow phosphorus to a thermal conversion reaction in a closed reaction zone. To this end, a hollow shaft-provided and closed ball mill is preheated to a reaction temperature within the range 280.degree. to 590.degree. C. Yellow phosphorus is continuously introduced into the ball mill through the hollow shaft in quantities per unit time which permit the reaction temperature prevailing inside the ball mill to be maintained without supply of heat from the outside. More particularly, decreasing quantities of yellow phosphorus are introduced per unit time at increasing temperature and increasing quantities of yellow phosphorus are introduced per unit time at decreasing temperature within the limits specified. Red phosphorus is allowed to cool inside the ball mill, water is poured over it and the whole is subjected to wet-grinding. An aqueous suspension of red phosphorus is finally removed from the ball mill.

Abstract: Animal feed grade phosphates such as mono-calcium phosphate, di-calcium phosphate or mixtures thereof are produced by direct reaction between phosphoric acid and Ca-containing materials. A finely ground, preheated calcium carbonate suspension is brought to react with a suitable quantity of preheated phosphoric acid by introducing the reactants into a short, tubular reaction zone, open at one end, whereby development of gas and intensive mixing of the reactants in the reaction zone take place. The gas formed by the reaction expels or ejects the foaming reaction mixture from the tube-like reaction zone, the reaction being substantially completed while the individual particles of the mixture are freely suspended in air or gas, whereafter the reacted mixture is collected in the form of a free-flowing granulate having improved handling properties, without any further quenching treatment of the granules.

Abstract: The present invention relates to a process for reacting ammonia and wet process phosphoric acid to produce ammonium phosphates, which process comprises feeding the reagents to a vessel comprising two tubular members in fluid flow communication with one another and with a gas disengagement vessel, at least one of said tubular members being generally upright, the ammonia being fed to the basal portion of the upright member, the phosphoric acid being fed to the other tubular member; allowing the resultant reaction mixture to circulate spontaneously up the upright member, through the gas disengagement vessel and through the other member to the upright member; and recovering the ammonium phosphate reaction products from the reaction system.

Abstract: A method for scrubbing sulfur dioxide from gaseous streams using a calcium salt-containing aqueous liquor having 250-5000 parts per million of magnesium ion to enable fast and efficient return to operation following a period of interruption of the gaseous flow by adjusting the pH of the liquor to a value between 9.8 and 12.0 during said interruption to convert sulfite ion species in the liquor to solid magnesium hydroxide and prevent oxidation thereof, and adding magnesium-containing lime to the liquor after resumption of the scrubbing process when the pH of the inlet liquor has dropped below 9.8 to the previous operational mode.

Abstract: The invention relates to a method for the treatment of industrial effluent gases for the removal of sulphur dioxide, according to which the gases are contacted with an absorbing solution, containing alkali metal sulphite and bisulphite, the solution, before the contact stage, being pre-treated with air or other gas inert to the solution, preferably a gas devoid of oxygen, whereby the SO.sub.2 partial pressure of the solution is reduced, thus enhancing the SO.sub.2 removal from said effluent gases.

Abstract: Sulfur oxides are removed from waste gases containing the same by scrubbing the waste gas with an aqueous scrubbing solution containing the aluminate of sodium, potassium or ammonium and an additional compound selected from the group consisting of aluminum sulfate and alum.

Abstract: Pure Maddrell salt is produced by heating sodium phosphate to temperatures of 250.degree. to 420.degree. C. The sodium phospate used as starting material is sodium trimetaphosphate or a mixture of sodium trimetaphosphate with Maddrell salt, monosodium orthophosphate or disodium pyrophosphate, the mixture containing Na and P in a molar ratio of 1:1. Prior to heating the starting material, it is admixed with 0.5 to 5 weight% of orthophosphoric acid, polyphosphoric acid, phosphorus pentoxide or at least one salt of a volatile base forming polyphosphoric acid at the temperatures specified. The resulting mixture is calcined over the period necessary to transform the starting material to Maddrell salt.

Abstract: The process of preparing analytically pure fluorapatite comprising reacting dicalcium phosphate dihydrate with hydrogen fluoride in aqueous solution, at a pH of from about 5 to about 8, at from about room temperature for about 7 days to about 100.degree. C. for about 2 days, the amount of fluoride ion being from about stoichiometric to about 1.1 times the stoichiometric amount of dicalcium phosphate dihydrate whereby solid analytically pure fluorapatite is formed.

Abstract: An improved Claus tail gas recovery process involving stoichiometric combustion of a hydrocarbon gas when the hydrocarbon gas composition is not constant.

Abstract: High quality carbon black forming material convertible with high yield into furnace black having a high abrasion resistance in rubber is prepared by dissolving pitch with conventional thinly liquid carbon black feed stock and mechanically separating suspended matter from the mixture obtained.

Abstract: A controlled process for the removal of sulfur oxides from gases by scrubbing with ammoniacal solutions in such a manner that the formation of sub-micron liquid particles (fog) is prevented at any point during the scrubbing operation, thereby preventing the formation of a plume (particulate matter) emission in the vapor effluent from the scrubbing.

Abstract: A process for removal of particulate material and sulfur dioxide from a gas stream by washing the gas stream in a treatment zone in a wet scrubber by injection of a reactant such as high calcium or magnesium lime to control pH in the range of 6.0 to 8.5. A resultant slurry containing calcium sulfate, calcium sulfite and solids is formed in the scrubber and a controlled quantity of the solids containing slurry is recycled to the scrubber washing zone as part of the washing fluid to aid in co-precipitation by providing nucleation sites for the calcium sulfate and sulfite crystals maintaining an unsaturated calcium sulfate level in the slurry.

Abstract: A process for producing ammonium phosphate that is substantially free of arsenic which comprises:(a) reacting crude phosphoric acid containing dissolved arsenic having a +5 valence state with ammonia and arsenic-reducing agent in sufficient proportions to form an ammonium phosphate solution and to reduce the arsenic from the +5 valence state;(b) forming ammonium phosphate crystals from said solution, leaving a mother liquor that contains substantially all of said arsenic; and(c) recovering said ammonium phosphate crystals that are substantially free of arsenic from said mother liquor.