Mechanical solid-state reduction of haematite with magnesium

Single-step displacement reaction has occurred during ball milling a mixture of haematite and magnesium powders at room temperature. During the early stage of milling (0-43 ks), the Fe2O3 particles are embedded into the soft matrix of Mg (reducing agent) particles to form coarse composite powders of the reactant materials. Increasing the milling time (86 ks) leads to the formation of fresh active surfaces of Mg which have high reducing potential and reacts with the Fe2O3 in a typical oxidation/reduction reaction. After 432 ks the Mg powders are completely oxidized to MgO, whereas the Fe2O3 is reduced successfully to metallic Fe. Increasing the milling time to 540 ks leads to the formation of ultrafine powders that have excellent morphological characteristics (spherical-like shape morphology) with an average diameter of 0.5 mum. The powders of these end-product contain very fine cells of MgO that Ne embedded into the metallic matrix of Fe. (C) 2001 Elsevier Science B.V. All rights reserved.