charcoal and C denotes fixed carbon. Reaction (2) represents the liberation of water from the cement during the The rate of reaction between iron oxides and heating of the pellet. charcoal, agglomerated together as pellets, hasThe thermal decomposition of charcoal is an endothermic been correlated with the swelling of the pellets and reaction. It starts in the temperature range 573-773 K. The with the morphology of the iron formed. The products of such a reaction induce reactions ( 4)-( 6). experimental techniques employed wereThe products of these reactions cause the gasification of thermogravimetric analysis, X-ray diffraction the reducing agent, reactions ( 7) and ( 8), which generates analysis, and microscopic examination of partially reducing gas (CO and H 2 ). reduced pellets. The experiments were performed Therefore, the reduction of a self-reducing pellet involves in the temperature range 1223-1423 K. The two types of reaction: conditions that favour the growing of iron in the (i) direct reaction (solid-solid) between iron oxide and form of whiskers, and hence lead to catastrophic carbon and swelling, have been determined.I&S/1400 (ii) a sequence of gas-solid reactions. As the solid-solid reaction is very slow compared with the

The steps Fe203+Fe304,

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