Thermodynamic Justification of the Dephosphorization of Manganese Ores and Concentrates in a Reducing Atmosphere

Resumo

The dephosphorization of manganese ores and concentrates in a reducing atmosphere is thermodynamically analyzed. It is shown that phosphorus can completely pass to a gas phase in a closed reaction system in a wide temperature range (1000–1800°C) at the amounts of a reducing gas (CO) that exceed the stoichiometric minimum required for reduction reactions. The gaseous products of reduction is found to contain phosphorus in the form of mainly polyatomic “heavy” molecular oxides, which can decrease the real effect of dephosphorization as compared to that obtained by equilibrium calculations because of kinetic factors. A thermodynamic simulation of a flow reaction system shows that almost complete transition of phosphorus to light gaseous substances (PO, P₂) is thermodynamically possible at the temperatures that are close to the technological operation temperatures. This transition is provided by the ratio of the rate of formation of volatile phosphorus-containing substances to the rate of their removal from reaction regions.