Mechanisms of Pig-iron Making from Magnetite Ore Pellets Containing Coal at Low Temperature

Abstract

A new pig-iron making process using magnetite ore pellets containing coal as reducing agent has been investigated. The pellets were heated rapidly in argon at furnace temperatures between 1 573 and 1 723 K and the temperature and partial pressure of oxygen in the pellets were recorded in situ. Molten iron containing 1.1–3.6 mass% carbon over the composition on the liquidus line of iron–carbon system was produced at the furnace temperatures higher than 1 598 K within 16 min. The whole process consists of four steps, i.e., heating, reduction of iron ore, carburization and melting of pig iron. The solution-loss of carbon and the reduction of iron ore are coupled and concentrically take place from the surface to centre due to the heat transfer control because of the endothermic reaction of solution-loss. The reduced iron particles were carburised by CO gas, rapidly absorbed carbon from coal and become molten pig iron particles. The particles cohered to make large drops and the pellet suddenly collapsed to melt. The conditions determining the lowest temperature for producing pig iron are discussed.