Selective reduction of iron in high phosphorus oolite ores to production low phosphorus metal

Abstract

The possibility of selective reduction of iron in oolite ore with the production of low-phosphorous metal after pyrometallurgical separation of metallized material is shown. To exclude the transition of phosphorus to metal during separation melting, lime was added to the crushed initial ore. The resulting mixture was fired in a Nabertherm muffle furnace in an air atmosphere at a temperature of 1200 °C and a holding time of 1 hour. During firing, iron phosphate is destroyed with the formation of stronger calcium phosphates. Solid-phase metallization of offlussed and non-fluxed oolitic ores was carried out in a Tamman laboratory furnace at a temperature of 1000 °C in a reducing atmosphere containing carbon monoxide CO. The results of the study of the phase composition of metallization products, as well as the chemical composition of the phases are presented. According to the results of the study, only iron is reduced by carbon monoxide CO, and phosphorus remains in the oxide phase. During metallization of the fluxed ore, phosphorus remains in the oxide phase in the form of aluminum and calcium phosphates, iron is reduced to metal. In unfluxed ore, iron is only partially recovered under such conditions and is present in samples in the form of metallic iron, as well as magnetite and fayalite. Phosphorus in the metallized samples is contained in the form of iron, calcium and aluminum phosphate. Experiments on liquid-phase pyrometallurgical separation of metallized samples were carried out in a verti-cal Nabertherm furnace at a temperature of 1600 °C. As a result of the melting of metallized unfluxed ore, metal and slag are practically not separated. Metal and slag samples were obtained from the melting of metallised fluxed ore. X-ray microanalysis shows that the phosphorus content in the metal phase is 0.1 % (wt.), and 0.3 % (wt.) in the slag. The residual amount of iron in the oxide phase after melting of the unfluxed ore is significantly greater than the amount of iron after melting of the offluxed ore.