Agglomeration of lateritic ores: effect of feed ore chemical and mineralogical composition
Date
2012
Authors
Quaicoe, I.
Nosrati, A.
Skinner, W.
Addai Mensah, J.
Editors
Davies, C.
Patterson, D.
Patterson, D.
Advisors
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Conference paper
Citation
Chemeca 2012: quality of life through chemical engineering, 2012 / Davies, C., Patterson, D. (ed./s), pp.1963-1973
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Chemeca 2012: Annual Conference of Australian and New Zealand Engineers (23 Sep 2012 - 26 Sep 2012 : Wellington, New Zealand)
Abstract
Despite the low capital investment and operating costs of heap leaching processing of lowgrade lateritic ores, its commercial application is limited. This is mainly due to paucity of knowledge to form porous but robust agglomerates and geotechnically stable heaps that withstand long acid leaching cycles. Successful agglomeration of finely crushed ores into coarse and robust agglomerates is, thus, a key precursor for an efficient heap leaching operation. In this study, the agglomeration behaviour and granule attributes of single and mixed clay (kaolinite and smectite) and oxide (hematite and quartz) minerals which constitute predominant host gangue mineral phases of a typical nickel (Ni) laterite ore were examined. Specifically, the impact of feed ore mineralogy on binder (H2S04 solution) dosage requirement, powder wetting, nucleation and growth mechanism as well as agglomerate strength and rewetting stability was investigated. The results showed that increasing clay content in feed ore leads to higher binder requirement for initial wetting and nucleation, but subsequently slows down the granule growth rate which occurs mainly via pseudo layering. Feed ore with high oxide content, on the other hand, requires lower binder dosage but displays faster granule growth which occurs via random coalescence. The observed difference in binder dosage is attributed to the higher specific surface area and greater acid consuming nature of clay minerals in contrast with ofoxides. Synergistic interaction of mixed oxide-clay mineral particles leading to significantly enhanced agglomerate strength is observed. The results further revealed that post-agglomeration curing dramatically enhances agglomerate compressive strength but reduces their re-wetting stability. These findings can be useful for benchmarking the agglomeration behaviour and granule properties of real laterite ores of equivalent chemical and mineralogical compositions.
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Copyright 20152 Engineers Australia