Chemical Speciation of Iron and Cobalt Dopants in an Industrial Nickel Oxide System

Abstract

The work presented is an X-Ray Absorption Fine Structure (XAFS) investigation into the speciation of cobalt (Co) and iron (Fe) dopants in Vale-INCO’s industrial doubly doped nickel oxide (NiO) system. The goal of the XAFS investigation was to reveal the local atomic structure(s) and species of the dopants. This information is a pre-requisite for investigating possible effects each respective dopant may have on Vale-INCO’s extraction yield of Nickel (Ni) from their NiO feed materials. This study utilized powder x-ray diffraction (PXRD), x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) experimental techniques respectively. It was determined from the XANES and EXAFS investigations that Co2+ is substitutional for Ni2+ with a locally compression of its octahedron. While the XANES investigation revealed that the iron dopant present is a mixed valence of Fe2+ and Fe3+.