Hoechst Aktiengesellschaft

Karl Rottgen

Herbert Diskowski

Joachim Stendel

The disclosure relates to a process for removing foreign components, especially zinc, from the product cycle during the production of yellow phosphorus inside and electrothermal furnace. To this end, the disclosure provides for molten ferrophosphorus and a calcium metasilicate slag and also a dust-containing gas mixture consisting essentially of carbon monoxide and phosphorus in vapor form to be taken from the furnace charged with phosphate pellets, coke and gravel. After electrostatic separation of the dust from the gas mixture, the dust is water-treated and made into a dust suspension. Crude phosphate is granulated on a granulating means using a mixture of dust suspension and binder which preferably is a clay suspension. The granulated material is calcined on a sintering device and made into phosphate pellets. A portion of the molten slag taken from the electrothermal furnace is allowed to solidify and the solidified slag is ground. The ground slag and at least a portion of dust suspension are granulated on a granulating means. The granulated slag and dust suspension are dried. It is possible for the dried granulated matter to be ground once again, to be granulated once again together with a further portion of dust suspension, and to be dried again. The dried and granulated matter is ultimately calcined and made into pellets.

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Erftstadt, Germany

Karl Rottgen