Gaseous reduction of magnetite superconcentrate compacts

Abstract

The reduction rate of superconcentrate magnetite compacts in the form of small discs has been investigated in the temperature range of 4000–1250°C using hydrogen as the reducing agent, andfrom 1000° to 1250°C using mixtures of hydrogen and carbon monoxide as the reducing agent. The maximum reduction rate for 100% reduction occurred at 570°C and a reduction rate minimum occurred at 750°Cfollowed by a second rate minimum at 960°C when hydrogen was the reducing gas. The initial rate of reduction increased with temperature over the complete temperature range but during the final stages of reduction the rate rapidly decreased. For 100% reduction at 570°C, the reduction rate with hydrogen wasfaster than at any other temperature with hydrogen or 100% carbon monoxide. Mixtures of hydrogen and carbon monoxide gave the fastest reduction rate and the time for total reduction decreased with increasing temperature. Increases in thickness of the superconcentrate discs increased the reduction time but at a rate less than direct proportionality. The calculated activation energies correspond with values determined by other investigators.