Doctor of Philosophy (Queensland University of Technology)
Research areas: My research focuses on the advancement of sustainable technologies, with an emphasis on recycling wastewater and waste residues produced by industry for the development of new materials and the optimisation of plant operations. I have a strong background in the treatment of industrial waste residues, development of adsorption media from industrial wastes and characterisation of materials. Over the years I have published 169 publications in over 16 different journals over the last 13 years. My research success is evidenced by my success in obtaining a IM-CRC, Queensland Accelerate Fellowship, ARC DECRA award, numerous commercial projects, internal QUT fellowships, citations, invitations to speak at industry conferences and numerous industry partnerships. Main areas of research:
- the development of processes in materials synthesis and water treatment
- the recovery of metals from acid mine drainage.
- the characterisation of a variety of minerals,
- the treatment of bauxite refinery residues, and
- the development of hydrotalcite adsorbents for water purification
Summary of accomplishments in these areas:
- 78 peer-reviewed articles have been published on mineral characterisation in journals such as the Journal of Raman Spectroscopy and Journal of Molecular Structure. I gained an interest in this research area from my PhD supervisor, Prof Ray Frost, with whom I continue to collaborate. For this work, rare or unusual minerals containing phosphates, arsenates, sulphates and rare earth metals are sourced from type localities around the world and characterised using, in the main, vibrational spectroscopy as well as complementary techniques. The aim of this research is to identify fundamental mineral structure changes based on geological formation conditions and to detail the influence of impurities within the crystal structure of particular mineral groups. Arsenate minerals have been of particular interest due to their potential to act as an arsenic sink for contaminated areas that have characteristics similar to locations/conditions in which natural analogues form. Interest in phosphate minerals is due to their potential application in the treatment or capture of phosphate from agriculture activities and their potential to act as a slow release fertiliser.
- My relationship with Rio Tinto Alcan began in 2006 as a vocational scholar and then during my PhD topic on environmental control processes used in the alumina industry. This relationship has led to numerous contributions to the field of Bayer chemistry. The Bayer process is used around the world for the extraction of alumina from bauxite ore. One of the industry’s greatest challenges is in the management of bauxite refinery residues (red mud), which is produced in enormous volumes and has significant environmental implications if not appropriately disposed or contained. Major contributions I have made in Bayer chemistry include; 1) determination of mineral compounds that cause pH reversion (i.e. a slow steady incline in pH over time) which has significant implications in terms of discharge regulations and the severity of risk in a dam failure event, 2) the development of methods to suppress reversion, 3) optimisation of the seawater neutralisation process to increase precipitate stability and settling rates, and 4) an in-depth phase analysis of red mud and seawater neutralised precipitates (Bayer hydrotalcite). These outcomes are presented over 16 publications in industry related journals, such as Industrial Engineering and Chemistry Research. A number of additional studies have been inspired by these findings including; 1) with Rio Tinto Alcan on optimising the seawater neutralisation process of bauxite refinery residues, 2) with Hatch on determination of the kinetic stability of seawater neutralised Bayer precipitates, and 3) with Talitha Santini (UQ) on the stability of these precipitates in land remediation.
- The by-product of the seawater neutralisation process is a layered double hydroxide mineral (Bayer hydrotalcite) that has huge potential in the water purification industry due to its versatility in adsorption and/or exchange reactions. Research on synthetic analogues shows that they are highly versatile adsorbent materials with the ability to remove anionic, cationic and organic molecules from solution depending on synthesis conditions. I have published 23 papers on the use of both synthetic and Bayer hydrotalcite materials and their application in the removal of a variety of ionic species, such as arsenate, molybdate and vanadate. More recently, I have optimised the formation of hydrotalcite specifically for the removal of heavy metals, using thermal activation and cheating agents.
- I have been involved in a number of commercial research projects with Santos GLNG, QGC and Arrow Energy in collaboration with Prof. Graeme Millar (QUT) and Prof. Ian Mackinnon (QUT) on coal seam gas water. The investments made by these companies has enabled our research group to commission the construction of an ion exchange pilot plant capable of treating 100kL per day of wastewater. In addition, the design of this pilot plant affords opportunity to trial different ion-exchange procedures (e.g. multiple columns in parallel or series) using different combinations of exchange materials. This facility is also being used in metal recovery projects. My involvement in numerous commercial projects has helped to create a research environment that has numerous bench scale technologies (ion exchange, electrocoagulation, forward osmosis, membrane distillation and ultra-filtration, hydrofloatation) commonly used to treat industrial wastewater.
- My research has also focussed on the recovery of valuable metals from acid mine drainage waters and mine tailings. This work is being conducted under my Queensland Accelerate Fellowship and with the assistance of the Queensland Department of Natural Resources and Mines. As part of this research Matthew Dunbabin (QUT) and have developed a robotic boat that is capable of creating spatial maps of mine pit lakes, as well as being able to produce water quality profiles from in-line monitoring and corresponding water samples.
- More recently, I am leading a research team that is transforming clay into high purity alumina (HPA), with applications in Li ion batteries and LEDs. The research team has been de-risking the mineral processing route and are building a pilot plant at IFE's Banyo Research Facility in early 2020. This pilot plant will be integrating machine learning to improve the plant's performance but also provide it with the versatility to produce tuneable HPA products based on end user specifications.
- Metal recovery from mining wastes
- Alumina processing, waste management - beneficial use options, and the optimisation of the seawater neutralisation process
- Mining wastewater treatment – adsorbents, ion exchange, clarification and dissolved air floatation
- Development of adsorbent materials using recycled mining wastes for heavy metal removal
- Mineral characterisation and optimisation of mineral processing operations
- Analytical capabilities – range of water analysis techniques, spectroscopy, X-ray diffraction, thermal analysis, surface science techniques and electron microscopy
- Palmer, S., Grand, L. & Frost, R. (2011). The synthesis and spectroscopic characterisation of hydrotalcite formed from aluminate solutions. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 79(1), 156–160. https://eprints.qut.edu.au/41331
- Palmer, S. & Frost, R. (2011). Characterization of bayer hydrotalcites formed from bauxite refinery residue liquor. Industrial & Engineering Chemistry Research, 50(9), 5346–5351. https://eprints.qut.edu.au/52063
- Palmer, S. & Frost, R. (2011). Effect of pH on the uptake of arsenate and vanadate by hydrotalcites in alkaline solutions: a Raman spectroscopic study. Journal of Raman Spectroscopy, 42(2), 224–229. https://eprints.qut.edu.au/40115
- Palmer, S., Frost, R. & Smith, M. (2011). Minimising reversion, using seawater and magnesium chloride, caused by the dissolution of tricalcium aluminate hexahydrate. Journal of Colloid and Interface Science, 353(2), 398–405. https://eprints.qut.edu.au/43088
- Palmer, S. & Frost, R. (2010). Use of hydrotalcites for the removal of toxic anions from aqueous solutions. Industrial & Engineering Chemistry Research, 49(19), 8969–8976. https://eprints.qut.edu.au/37277
- Palmer, S. & Frost, R. (2010). Thermal decomposition of Bayer precipitates formed at varying temperatures. Journal of Thermal Analysis and Calorimetry, 100(1), 27–32. https://eprints.qut.edu.au/31838
- Palmer, S., Soisnard, A. & Frost, R. (2009). Determination of the mechanism(s) for the inclusion of arsenate, vanadate, or molybdate anions into hydrotalcites with variable cationic ratio. Journal of Colloid and Interface Science, 329(2), 404–409. https://eprints.qut.edu.au/15729
- Palmer, S., Frost, R. & Nguyen, T. (2009). Hydrotalcites and their role in coordination of anions in Bayer liquors: Anion binding in layered double hydroxides. Coordination Chemistry Reviews, 253(1-2), 250–267. https://eprints.qut.edu.au/15728
- Palmer, S. & Frost, R. (2009). The effect of synthesis temperature on the formation of hydrotalcites in bayer liquor: a vibrational spectroscopic analysis. Applied Spectroscopy, 63(7), 748–752. https://eprints.qut.edu.au/41980
- Palmer, S., Frost, R. & Nguyen, T. (2008). Thermal decomposition of hydrotalcite with molybdate and vanadate anions in the interlayer. Journal of Thermal Analysis and Calorimetry, 92(3), 879–886. https://eprints.qut.edu.au/13513