Time-resolved diffraction studies into the pressure acid leaching of nickel laterite ores: a comparison of laboratory and synchrotron X-ray experiments

This paper compares time-resolved diffraction experiments that have been performed using laboratory and synchrotron X-ray sources. The experiments investigated the mechanism and kinetics of pressure acid leaching of nickel laterite ores. The sample environment was a purpose-built capillary reaction vessel, and extensive method development was conducted in the laboratory using Mo Kα radiation prior to repeating and extending the experiments at the Daresbury Synchrotron Radiation Source, beamline MPW6.2. In general, the synchrotron results confirmed the findings from previously reported laboratory work and also confirmed the presence of a minor phase that had been ambiguous in the laboratory experiments, i.e. the formation of hematite in the pressure acid leaching of saprolite. The synchrotron measurements also extended the experimental programme to include poorly diffracting laterite components that could not be examined in the laboratory, e.g. nontronite. The results from these components supported the reaction mechanisms determined from ex-situ analyses conducted in larger scale autoclaves.