REDUCTION OF NICKEL-OXIDE BY CARBON .2. INTERACTION BETWEEN NICKEL-OXIDE AND NATURAL GRAPHITE

The interaction of micron-sized particles of NiO with plate-like parti cles of natural graphite has been studied at 950 degrees C using scann ing electron microscopy. The gases evolved (CO and CO2) upon reduction of NiO to Ni were continuously pumped out of the system. The graphite particles consisted of highly aligned, large crystallites. Attack occ urred predominantly at the edge of prismatic surface of the particles, which constituted only 4-5% of the total surface area. Nickel produce d in the reduction reaction covered the NiO with a sintered layer. Rem oval of the Ni layer revealed unsintered particles of NiO of similar s hape to the original particles. The particles showed considerable poro sity, presumably a result of selective attack at cracks in the NiO pro duced as reaction proceeds. (C) 1997 Elsevier Science Ltd.