Centrifugal ironmaking.

A process for producing liquid iron from iron ore is being developed on the pilot plant scale that avoids the use of high grade metallurgical coal and the agglomeration of iron ore concentrates. The use of a centrifuge furnace provides the maximum surface area for reaction between layers of molten iron oxide and solid carbon. The iron product is centrifuged to the walls of the reactor where it provides a protective barrier between the highly corrosive liquid slag and the refractory walls. Carbon monoxide, released from the reduction reaction, combusts with oxygen in the central gas core and the heat produced is radiated back to the reacting species.To help understand the interaction of the various physical and chemical reactions occurring inside the reactor, a mathematical model had been written describing the process. Laboratory scale studies were carried out to examine and test the validity of some of the assumptions used in the model, and where necessary modify these assumptions. Two such investigations were the reaction between solid carbon and liquid iron bearing slags at temperatures up to 2 135 K, and the determination of heat and mass transfer coefficients from the central gas core to the rotating bed using a naphthalene sublimation technique.To widen the basis on which the predictions from the model could be compared with actual pilot plant operating data, a series of experiments were carried out on the plant covering a broad range of input conditions. These experiments were carried out in the batch mode i.e. the raw materials were charged into the furnace until its capacity was reached, after which the entire contents were discharged, analysed, and compared with the predictions from the mathematical model. A systematic empiricalcampaign was then carried out to determine more realistic values for the parameters used in the model. Sufficient information was obtained from this study to provide the optimum conditions for attempting continuous ironmaking operations on the pilot plant.Three continuous ironmaking experiments were carried out, with the maximum length of continuous operation in any one experiment being of ten hours duration. Improvements in operation and measurement techniques enabled process data to be collected at regular intervals which allowed the process efficiency to be determined on a continuous basis.The iron ore input rate was held constant at kg/h and high conversionefficiencies of iron from iron ore of up to 80% were obtained.