Mineralogical transformations of spodumene concentrate from Greenbushes, Western Australia. Part 1: Conventional heating

摘要

Spodumene is a lithium aluminium silicate which can exist in alpha, beta and gamma modifications. Phase transformations of spodumene concentrate from the beneficiation plant in Greenbushes, Western Australia, were studied under a conventional method of heating. Spodumene concentrate was heated in a muffle furnace at 800, 850, 900, 950,1000, 1050 and 1100 degrees C for 10, 20, 30 and 60 min in order to evaluate the effect of temperature and heating time on the amount of alpha-spodumene converted to beta-spodumene, and also to assess the possibility of gamma-spodumene formation. Structural changes were first observed after heating at 950 degrees C for a minimum of 30 min. Lower temperatures or residence times did not result in evident phase change while higher temperatures or residence times increased the extent of the phase change. At 1100 degrees C and for times longer than 10 min, the transformation from alpha-spodumene to gamma and beta-spodumene was complete. It also resulted in volumetric expansion of the sample and change of colour from beige to ice white. X-ray diffraction spectra and scanning electron microscope images also provided evidence of gamma-spodumene formation from 950 degrees C up to 1100 degrees C. Samples were analysed in order to investigate changes in their physical properties. The results revealed that specific surface is directly related to the amount of beta-spodumene which forms at higher temperatures. On the other hand particle size and specific gravity reduced with formation of more beta-spodumene. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.