School of Chemical Engineering

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The department has a strong research team that is focused on solving problems and providing answers for industry and the wider community. Our work is principally in the areas of:

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School of Chemical Engineering
Ingkarni Wardli Building
THE UNIVERSITY OF ADELAIDE
SA 5005
AUSTRALIA
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Browsing School of Chemical Engineering by Author "Abaka-Wood, G.B."

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    A study of flotation characteristics of monazite, hematite, and quartz using anionic collectors
    (Elsevier, 2017) Abaka-Wood, G.B.; Addai-Mensah, J.; Skinner, W.
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    A study of selective flotation recovery of rare earth oxides from hematite and quartz using hydroxamic acid as a collector
    (Elsevier, 2018) Abaka-Wood, G.B.; Addai-Mensah, J.; Skinner, W.
    Monazite is a major rare earth elements (REE)-bearing phosphate mineral predominantly found in association with hematite and quartz in some Australian rare earth deposits. The flotation of rare earth oxides (REO) in monazite from mixtures containing monazite, hematite, and quartz with hydroxamic acid as a collector has been investigated using an IMN microflotation cell and a 1.2 L Denver flotation cell. Maximum flotation recovery of both monazite and hematite was attained at pH 7, whereas that of quartz, at pH 3. The flotation kinetics data indicated the need for depressants to achieve selective REO recovery from hematite and quartz mixtures. Sodium silicate and starch were thus tested as depressants of both hematite and quartz. The separation efficiency of REO in the absence of depressants was low and averaged 6.42% at 99% REO recovery, but could be increased to 44.78% with corresponding 93% REO recovery when 4000 g/t starch was used. However, the efficiencies of REO separation obtained with sodium silicate were generally lower (<18%), due to higher gangue minerals content in the flotation concentrates. A blend of sodium silicate and starch showed a good performance for REO recovery, with enhanced selectivity against hematite and quartz through a rougher-cleaner flotation test. This study presents the feasibility of upgrading REO from iron-oxide rich tailings using hydroxamic acid, in the presence of sodium silicate and starch as depressants.
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    A study of the feasibility of upgrading rare earth elements minerals from iron-oxide-silicate rich tailings using Knelson concentrator and Wilfley shaking table
    (Elsevier, 2019) Abaka-Wood, G.B.; Quast, K.; Zanin, M.; Addai-Mensah, J.; Skinner, W.
    A number of gravity separation techniques for rare earth elements (REE) minerals have been investigated and reported in the literature. These include the use of dense/heavy media, Falcon concentrators, Knelson concentrators, spiral concentrators, laboratory scale jigs, and shaking tables. Most of these methods have provided considerable REE minerals recovery and upgrade; but remain at the laboratory testing stage. There are vast quantities of iron-oxide-silicate rich tailings (IST) containing low grade REE in Australia. This work is part of research and development studies currently underway at the University of South Australia to develop economically viable methods to exploit selected IST for their REE contents. In this investigation, the feasibility of exploiting the differences in specific gravity to concentrate REE minerals from a typical IST sample was studied using two gravity separation units, a Knelson concentrator (KC) and Wilfley shaking table. The feed sample and gravity separation products were characterised using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) to study and compare the performance of the KC and shaking table as gravity preconcentration methods. The results indicated that the performance of both the KC and shaking table are significantly dependent on the mineralogical and particle size characteristics of the feed, however, the tabling was found to be the preferred choice over the KC, due to its greater selectivity. Tabling of >38 μm feed samples produced the desired split between the iron oxides and silicate minerals. The results suggest that desliming of the feed to remove fine/ultrafine particles (<38 μm) prior to tabling is key to attaining the desired results with the shaking table. Overall, tabling produced appreciable REE minerals upgrade, with iron oxides occupying the bulk of the concentrates. The test results confirm the complex mineralogy of the IST, which compromised REE minerals upgrade. A modified concentration criterion expression which considers the liberation characteristics of minerals is proposed, which provides a better idea on the feasibility of gravity separation.
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    Flotation recovery of rare earth oxides from hematite-quartz mixture using sodium oleate as a collector
    (Elsevier, 2019) Abaka-Wood, G.B.; Fosu, S.; Addai-Mensah, J.; Skinner, W.
    Froth flotation plays a significant role in the beneficiation of rare earth elements (REE) minerals from differing ores. Monazite has been identified as one of the principal REE minerals in most iron oxide silicate rich tailings generated in Australia from the extraction of primary commodities such as copper and gold. These tailings generally contain hematite and quartz as the major gangue minerals. A previous investigation has identified almost identical flotation response between monazite and hematite in the presence of anionic collectors. Therefore, it is necessary to investigate the feasibility of selective flotation of rare earth oxides (REO) in monazite from hematite–quartz mixtures, to identify cost-effective processing methods. The flotation conditions for selective REO separation from model minerals mixtures were tested in a 1.2 L Denver flotation cell using sodium oleate as a collector. Sodium silicate and starch were tested as depressants for hematite and quartz. Results from the flotation tests revealed that the increased dosage of sodium oleate led to an increase in REO recovery with a corresponding decrease in upgrade, and increased hematite (Fe₂O₃) and quartz (SiO₂) recoveries. In the absence of depressants, the separation of REO from a low grade mixture (0.83% REO feed grade) was unselective, where 3000 g/t sodium oleate recovered 98% REO at a grade of 1.31% (enrichment ratio, E = 1.58) along with 77% Fe₂O₃ and 37% SiO₂ recoveries. However, the depressants reduced the flotation recovery of Fe₂O₃ and SiO₂, which was shown by an improvement in REO grade. The flotation recovery of REO decreased to 84% with a corresponding increase in grade to 4.13% when 1000 g/t sodium silicate was used in the presence of 3000 g/t sodium oleate. Furthermore, 1000 g/t starch in the presence of 3000 g/t sodium oleate increased REO concentrate grade to 5.56% although the recovery decreased to 65%. Subsequently, a rougher–scavenger flotation test conducted with the mixed depressants (sodium silicate: starch, 1:1) produced a final concentrate recovering 61% REO at a grade of 6.25%. This study has shown that REO can be separated selectively from hematite–quartz rich mixtures by flotation when using sodium oleate as the collector and sodium silicate and starch as depressants.