Effect of magnetic field on reduction of nickel oxide

Abstract

“IN 1872, US patent No. 133099 on the use of a magnetic coil for ‘Improvement in Reduction of Ores, etc.’ was granted to Abraham T. Hay, of Burlington, Iowa¹. It was a failure.” Thus stated Skorski² who a century later reported that the reduction rate of haematite (Fe₂O₃) with H₂ was considerably enhanced by application of 500- and 1,400-oersted magnetic fields as compared with reduction in the Earth's field (∼0.5 oersted). Skorski² also used CH₄ and CO for the reduction, but found the rate in these cases was slower in a strong magnetic field than in the Earth's field. He concluded that the effect must be dependent on the magnetic properties of H₂ itself rather than on those of Fe and its oxides. This notion was immediately challenged by Svare³ who demonstrated that the magnetic properties of H₂ are not significantly different from those of CO and CH₄ in the context of the reaction involved. Peters⁴, however, argued that the observed acceleration in reaction rate is predictable from thermodynamics theory when product and reactant species differ widely in their magnetic properties—as do Fe₂O₃ and metallic Fe (or NiO and metallic Ni) for example. One can readily view this argument qualitatively in terms of Le Chatelier's principle.