Changes in an Australian laterite ore in the process of heat treatment

This paper examines an Australian garnieritic-type ore and changes in phase composition and morphology caused by heating in argon at 400–1000 °C using XRF, XRD, DTA/TG, SEM/EDS and BET analyses. The mineral phases detected by XRD in the original ore include chlorite, talc, hematite and quartz. Traces of iron silicate, Fe–Cr spinel and monoxide phase (predominantly manganese oxide) were observed by EDS. Nickel was detected in chlorite, talc, iron silicate and monoxide phase. Heat treatment at 400–500 °C did not change XRD patterns. At 600 °C, dehydroxylation of the brucitic phase of chlorite occurred. Chlorite was converted into olivine (forsterite) and enstatite at 600–800 °C. Upon heating to 900–1000 °C, talc was also converted into olivine and enstatite. Ni-bearing phases after heat treatment at 800–850 °C were forsterite, enstatite, talc, iron silicate and monoxide.