Erco Industries Limited

Tenneco Canada Inc.

Tenneco Canada Inc. (erco Division)

James D McGilvery

Zbigniew Twardowski

Marek Lipsztajn

Helena Twardowska

Slawomir M Cybulski

Vicram P Singh

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.

Preparation of phosphorous acid

Chlorine dioxide is produced electrolytically in the cathode compartment of an electrolytic cell using a three-dimensional high surface-area cathode. The cathode compartment is separated from an anode compartment by a cation-exchange membrane. Sodium chlorate is reacted with hydrogen ions and chloride ions in the cathode compartment and chlorine dioxide is vented from the cathode compartments. Chlorine co-produced with the chlorine dioxide is reduced at the cathode to provide chloride ions for the reaction while electrolytically-produced hydrogen ions are transferred across the membrane from the anode compartment to the cathode compartment to provide hydrogen ions for the reaction.

Production of chlorine dioxide in an electrolytic cell

Chlorine dioxide is transferred by membrane pervaporation from one chamber filled with aqueous chlorine dioxide-generating reactants or other chlorine dioxide donor medium across a gas-permeable hydrophobic membrane to a recipient aqueous medium filling a second chamber. The recipient medium may be water, pulp suspension or sodium chlorite solution. The membrane typically is expanded polytetrafluoroethylene.

Membrane pervaporation process

Stable aqueous solutions of sodium polyphosphate useful in granulating dry solid cleaning composition components are formed by direct reaction of polyphosphoric acid with sodium carbonate generally at a temperature of about 50.degree. C. The reactants are used in an Na:P ratio of 1.2:1 to 1.5:1, and the product solution contains about 32 to about 37% w/w P.sub.2 O.sub.5 of which a high proportion is present as polyphosphate and has a pH of about 5 to about 6.5.

Production of sodium polyphosphates

Particulate red phosphorus is obtained by thermal conversion of white phosphorus in an essentially dry process in which liquid white phosphorus is injected onto a bed of red phosphorus particles preheated to a temperature above the thermal conversion temperature while controlling the heat generation.

Manufacture of red phosphorus

Red phosphorus, usually in amorphous form, is obtained by heating liquid white phosphorus at a temperature of between 250.degree. and 590.degree. C. while the phosphorus is subjected to a pressure greater than the theoretical vapor pressure of white phosphorus at the heating temperature. The application of such pressure minimizes phosphorus vapor formation during the conversion to red phosphorus. The process may be carried out by feeding liquid white phosphorus into an extrusion head heated to the reaction temperature while subjecting the white phosphorus to the appropriate pressure in the extrusion head, the red phosphorus being extruded from the extrusion head into an inert atmosphere. Alternatively, molten white phosphorus in droplet form may be pumped into an inert immiscible heat exchange fluid, such as, lead, at the reaction temperature, the appropriate pressure applied in the fluid and particulate red phosphorus separated from the fluid.

Production of red phosphorus

A low density, free-flowing, granular phosphate product having a high oil absorption capacity and capable of dissolving in water to provide a solution of pH about 7 to 8 is provided by mixing a hydratable alkali metal phosphate, polyphosphoric acid, and sodium carbonate and/or sodium bicarbonate and granulating the mixture with water.

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Etobicoke, Canada

James D McGilvery