Process for removing metallic constituents from dust obtained during theelectrothermal production of yellow phosphorus

Abstract From the Canadian patent

Metallic constituents, especially heavy metal constituents are removed from dust electrostatically separated from a gas mixture consisting substantially of carbon monoxide and phosphorus in vapor form obtained during the electrothermal production of yellow phosphorus. To this end, the dust is initially calcined with continuous agitation under oxidizing conditions at temperatures of 300 to 800°C; next, the resulting calcined matter is mixed with carbon and the mixture is treated at temperatures of 950 to 1200°C under reducing conditions with volatilization of the metallic constituents; and the volatilized metallic constituents are ultimately condensed and separated.