1989 Volume 29 Issue 7 Pages 580-588
A new solid state processing route for making steel strip has been proposed which basically consists of making sponge iron block directly from magnetite superconcentrate powder, followed by its hot and cold rolling. Preliminary experiments on the making of sponge iron block direct from magnetite superconcentrate powder have been made. They consist of mixing magnetite superconcentrate powder with a naturally occurring water soluble Babul gum binder. The mixture is compacted into a block shape which is subsequently reduced at high temperatures in a vertical shaft furnace with a variety of solid reductants to produce a sponge iron block. The effect of binder content and superconcentrate/water ratio on the crushing strength of green superconcentrate block has been studied. It has been shown that Acacia Arabica binder could produce a sufficiently strong block of magnetite superconcentrate at a low concentration. The reduction behaviour of the green superconcentrate blocks has been investigated using lignite char, charcoal and saw dust charcoal. Lignite char has been found to be a better reducing agent in comparison to other two. The structural changes occurring in the magnetite superconcentrate block during reduction is also discussed. It was observed that at 1 427 K, the block as a whole reduced in a topochemical manner, and the reaction interface was diffuse. At 1 273 K, the reaction interface was spread over the entire cross-section of the block. The carbon content of the sponge iron block was not same at all the areas of the block, and was a function of time at a given reduction temperature.
It has been shown that it is possible to obtain crack free sponge iron blocks from magnetite superconcentrate blocks by reduction in a bed of solid reductant.
