A diverse pleistocene marsupial trackway assemblage from the Victorian Volcanic Plains, Australia
- Authors: Carey, Stephen , Camens, Aaron , Cupper, Matthew , Grun, Rainer , Hellstrom, John , McKnight, Stafford , McLennan, Iain , Pickering, David , Trusler, Peter , Aubert, Maxime
- Date: 2011
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 30, no. 5-6 (2011), p. 591-610
- Full Text: false
- Reviewed:
- Description: A diverse assemblage of late Pleistocene marsupial trackways on a lake bed in south-western Victoria provides the first information relating to the gaits and morphology of several megafaunal species, and represents the most speciose and best preserved megafaunal footprint site in Australia. The 60-110 ka volcaniclastic lacustrine sedimentary rocks preserve trackways of the diprotodontid Diprotodon optatum, a macropodid (probably Protemnodon sp.) and a large vombatid (perhaps Ramsayia magna or '. Phascolomys' medius) and possible prints of the marsupial lion, Thylacoleo carnifex. The footprints were imprinted within a short time period, demonstrating the association of the taxa present, rather than the time-averaged accumulations usually observed in skeletal fossil deposits. Individual manus and pes prints are distinguishable in some trackways, and in many cases some digital pad morphology is also present. Several parameters traditionally used to differentiate ichnotaxa, including trackway gauge and the degree of print in-turning relative to the midline, are shown to be subject to significant intraspecific variation in marsupials. Sexual dimorphism in the trackway proportions of Diprotodon, and its potential for occurrence in all large bodied, quadrupedal marsupials, is identified here for the first time. © 2010 Elsevier Ltd.
Application of high voltage transmission electron microscopy to the study of ultra-fine grained ores
- Authors: McKnight, Stafford
- Date: 2004
- Type: Text , Conference paper
- Relation: Paper presented at The Minerals Industry - Future Directions for New Leaders', Ballarat, Victoria : 21st March, 2004
- Full Text: false
- Reviewed:
- Description: E1
- Description: 2003000706
Characterisation of Low-grade Hematite Ore Ultra-fine Size Fraction Particles by Heavy Suspension
- Authors: Koroznikova, Larissa , Begelhole, Jason , McKnight, Stafford
- Date: 2016
- Type: Text , Conference paper
- Relation: Third AusIMM International Geometallurgy Conference 2016 p. 327–334
- Full Text: false
- Reviewed:
Characterization and recovery of gold associated with fine, activated carbon
- Authors: Rowe, James , McKnight, Stafford
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at World Gold Conference 2009, Johannesburg, South Africa : 26th-30th October 2009
- Full Text:
- Description: The attrition of activated carbon, and the loss of gold associated with it, is of significant economic importance to the operation of a CIP/CIL circuit. The focus of this study was on activated carbon recovered from an elution circuit which was deemed too fine for reuse. Results of cyclosizer and laser particle size analysis identified that most of the carbon was contained in the larger size fraction suggesting formation by abrasion. Digestion and AAS analysis of the individual size fractions identified a disproportionate concentration of gold in the finer size fractions which was identified by scanning electron microscopy to be due to the presence of fine metallic gold formed as a result of the acid washing process. Attempts to strip the remaining gold using sodium hydroxide or sodium sulphide based solutions proved unsuccessful due to poor elution efficiencies and re adsorption of gold. Upgrading of the material by froth flotation was also investigated using various conventional flotation reagents which had some success in concentrating the free metallic gold, however, grade and/or recoveries were considered less than desirable. Greater success was ultimately found in the transfer of gold from the fine carbon material onto coarser virgin activated carbon using a caustic cyanide solution. Sodium sulphide, sodium chloride and ammonium chloride based solutions were also trialled but proved less successful owing to their inability to mobilise metallic gold or gold cyanide species. Repetition of the transfer process proved capable of stripping 97% of the gold contained on the carbon fines for a bed volume ratio of 6:1.
- Description: 2003007482
Co-encapsulation and characterisation of omega-3 fatty acids and probiotic bacteria in whey protein isolate-gum Arabic complex coacervates
- Authors: Eratte, Divya , McKnight, Stafford , Gengenbach, Thomas , Dowling, Kim , Barrow, Colin , Adhikari, Benu
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Functional Foods Vol. 19, no. (2015), p. 882-892
- Full Text: false
- Reviewed:
- Description: Omega-3 fatty acids and probiotic bacteria were co-encapsulated in a single whey protein isolate (WPI)-gum Arabic (GA) complex coacervate microcapsule. Tuna oil (0) and Lactobacillus casei 431 (P) were used as models of omega-3 and probiotic bacteria, respectively. The co-microcapsules (WPI-P-O-GA) and L. casei containing microcapsules (WPI-P-GA) were converted into powder by using spray and freeze drying. The viability of L. casei was significantly higher in WPI-P-O-GA co-microcapsules than in WPI-P-GA. The oxidative stability of tuna oil was significantly higher in spray dried co-capsules than in freeze dried ones. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.
Effect of pyrolysis conditions on bone char characterization and its ability for arsenic and fluoride removal
- Authors: Alkurdi, Susan , Al-Juboori, Raed , Bundschuh, Jochen , Bowtell, Les , McKnight, Stafford
- Date: 2020
- Type: Text , Journal article
- Relation: Environmental Pollution Vol. 262, no. (2020), p.
- Full Text: false
- Reviewed:
- Description: This study examined arsenite [As(III)], arsenate [As(V)] and fluoride (F−) removal potential of bone char produced from sheep (Ovis aries) bone waste. Pyrolysis conditions tested were in the 500 °C–900 °C range, for a holding time of 1 or 2 h, with or without N2 gas purging. Previous bone char studies mainly focused on either low or high temperature range with limited information provided on As(III) removal. This study aims to address these gaps and provide insights into the effect of pyrolysis conditions on bone char sorption capacity. A range of advanced chemical analyses were employed to track the change in bone char properties. As pyrolysis temperature and holding time increased, the resulting pH, surface charge, surface roughness, crystallinity, pore size and CEC all increased, accompanied by a decrease in the acidic functional groups and surface area. Pyrolysis temperature was a key parameter, showing improvement in the removal of both As(III) and As(V) as pyrolysis temperature was increased, while As(V) removal was higher than As(III) removal overall. F− removal displayed an inverse relationship with increasing pyrolysis temperature. Bone char prepared at 500 °C released significantly more dissolved organic carbon (DOC) then those prepared at a higher temperature. The bone protein is believed to be a major factor. The predominant removal mechanisms for As were surface complexation, precipitation and interaction with nitrogenous functional groups. Whereas F− removal was mainly influenced by interaction with oxygen functional groups and electrostatic interaction. This study recommends that the bone char pyrolysis temperature used for As and F− removal are 900 °C and 650 °C, respectively. © 2020 Elsevier Ltd
- Description: This research was performed as a part of PhD research which was supported in part by the Iraqi Government and the Australian Research Training Program.
Effect of spatial distribution of wax and PEG-isocyanate on the morphology and hydrophobicity of starch films
- Authors: Muscat, Delina , Adhikari, Raju , Tobin, Mark , McKnight, Stafford , Wakeling, Lara , Adhikari, Benu
- Date: 2014
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 111, no. (2014), p. 333-347
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- Reviewed:
- Description: This study proposes a novel method for improving surface hydrophobicity of glycerol plasticized high amylose (HAG) films. We used polyethylene glycol isocyanate (PEG-iso) crosslinker to link HAG and three natural waxes (beeswax, candelilla wax and carnauba wax) to produce HAG + wax + PEG-iso films. The spatial distributions of wax and PEG-iso across the thickness of these films were determined using Synchrotron-based Fourier transform infrared spectroscopy. The hydrophobicity and surface morphology of the films were determined using contact angle (CA) and scanning electron microscopic measurements, respectively. The distribution patterns of wax and the PEG-iso across the thickness of the film, and the nature of crystalline patterns formed on the surface of these films were found to be the key factors affecting surface hydrophobicity. The highest hydrophobicity (CA >90°) was created when the PEG-iso was primarily distributed in the interior of the films and a hierarchical circular pinnacle structure of solidified wax was formed on the surface. © 2014 Elsevier Ltd.
Estimating mineralogy in bulk samples
- Authors: Berry, Ron , Hunt, Julianne , McKnight, Stafford
- Date: 2011
- Type: Text , Conference proceedings
- Full Text: false
- Description: This paper looks at two ways to estimate the bulk mineralogy of the rocks for assay intervals. The aim is to find an efficient indicator of the most common minerals in the rock. Phase (modal) analysis has traditionally been done using visual methods such as point counting and image analysis. A modern version of this process is the X-ray point counting routine using the SEM-EDS based software. These methods are too slow and expensive for routine analysis of bulk sample mineralogy at the normal assay spacing. Two sources of data were considered that provide information that can be used to determine the mineral abundance in assay samples. The most widely applied method is (semi-) quantitative X-ray diffraction (QXRD). The QXRD method is most applicable to major minerals and has limited application to minerals at low abundance. The nominal detection limit is 0.5 per cent. Values below five per cent have large errors. A second, less common, method is calculation of mineralogy from chemical assay data. Conversion of chemical analyses to mineralogical analyses depends on the unique chemical composition of each mineral. Elements only found in one mineral are easily accounted for, but many compositions are ambiguous. Deciding on the actual mineralogy is not simple. Recalculation of mineral mode from chemical analyses is more accurate than QXRD when the correct minerals, and mineral compositions, are known. Where only a few QXRD analyses are available they can be used to setup a protocol for calculation of mineralogy from assay data. Linear programming works well in this environment. The best results are obtained when both H 2O and CO 2 are directly measured. Loss-on-ignition (LOI) should be included if these are not available. Where both QXRD and chemical analysis are available for all samples, the best results are obtained using the least squared method to merge the data sets assuming QXRD has much higher analytical errors than chemical assays. The combined method provides more robust results because the high abundance minerals are controlled by the QXRD measurements while the chemical assays improve the precision for low abundance minerals.
Evolution of the boundary between the western and central Lachlan Orogen : Implications for tasmanide tectonics
- Authors: Spaggiari, Catherine , Gray, David , Foster, David , McKnight, Stafford
- Date: 2003
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 50, no. 5 (2003), p. 725-749
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- Description: Differences in oblique overprinting, along-strike complexity as well as structural, metamorphic and timing constraints suggest that the boundary between the western and central subprovinces of the Lachlan Orogen, currently designated by the Governor Fault, cannot be a single structure. Previously limited data on the nature and kinematics of the fault/shear systems defining the boundary have led to varying scenarios for the tectonic evolution of the Lachlan Orogen. These scenarios either involve large-scale strike-slip displacement along the boundary with subsequent overthrusting or convergence of oppositely vergent thrust-systems with limited strike-slip translation. Geometrical constraints, fabric chronology and kinematic indicators in both the Mt Wellington (Melbourne Zone) and Governor (Tabberabbera Zone) Fault Zones indicate that maximum displacements relate to thrusting and duplex formation, followed by minor strike-slip faulting perhaps in response to slightly oblique collision of the Melbourne and Tabberabbera structural zones. Collision of these zones took place between ca 400 and 390 Ma. At Howqua, structural relationships indicate that collision involved northeast-directed thrusting of the Melbourne Zone (Mt Wellington Fault Zone) over the Tabberabbera Zone (Governor Fault Zone), and was followed by regional, northwest-trending, open folding. These structures overprint the dominant fabrics and metamorphic assemblages that are interpreted to relate to disruption and underthrusting of Cambrian oceanic/arc crust during closure of a marginal basin. Major deformation in the Tabberabbera Zone took place from ca 445 Ma and was associated with mélange formation, underplating and imbrication or duplexing (Governor Fault Zone, East Howqua segmennt). At slightly higher crustal levels, and following deposition of Upper Ordovician black shale and chert sequences (ca 440 Ma), Tabberabbera Zone evolution included offscraping of a serpentinite body (Dolodrook segment) that may have been either a Marianas-style seamount or transform fault zone within the Cambrian oceanic/arc crust. Major thrusting in the Mt Wellington Fault Zone was underway sometime after ca 420 Ma, and in contrast to the Governor Fault Zone, no mélange or broken formation was produced, metamorphism was at slightly higher temperatures and deformation probably occurred under higher strain states.
- Description: C1
- Description: 2003000547
Exploration tools for linked porphyry and epithermal deposits : Example from the mankayan intrusion-centered Cu-Au district, Luzon, Philippines
- Authors: Chang, Zhaoshan , Hedenquist, Jeffrey , White, Noel , Cooke, David , Roach, Michael , Deyell, Cari , Garcia Jr, Joey , Gemmell, J. Bruce , McKnight, Stafford , Cuison, Ana Liza
- Date: 2011
- Type: Text , Journal article
- Relation: Economic Geology Vol. 106, no. 8 (2011), p. 1365-1398
- Full Text: false
- Reviewed:
- Description: The Mankayan mineral district of northern Luzon, Philippines, hosts several significant ore deposits and prospects of various types within an area of ~25 km2, including the Far Southeast porphyry Cu-Au deposit, the Lepanto high sulfidation epithermal Cu-Au deposit, the Victoria intermediate sulfidation epithermal Au-Ag vein deposit, the Teresa epithermal Au-Ag vein deposit, the Guinaoang porphyry Cu-Au deposit, and the Buaki and Palidan porphyry Cu-Au prospects, all having formed in a period of about 2 m.y., from ~3 Ma. The geologic units include (1) a basement composed of Late Cretaceous to middle Miocene metavolcanic rocks and volcaniclastic rocks; (2) the Miocene 12 to 13 Ma tonalitic Bagon intrusive complex; (3) the Pliocene, ~2.2 to 1.8 Ma, Imbanguila dacite porphyry and pyroclastic rocks; and (4) postmineralization cover rocks, including the ~1.2 to 1.0 Ma Bato dacite porphyry and pyroclastic rocks and the ~0.02 Ma Lapangan tuff. Extensive advanced argillic alteration crops out for ~7 km along the unconformity between the basement rocks and the Imbanguila dacite formation and consists of quartz-alunite ± pyrophyllite or diaspore, with local zones of silicic alteration and a halo of dickite ± kaolinite. The alteration and its subhorizontal geometry indicate that it is a lithocap or coalesced lithocaps. The northwest-striking portion is ~4 km long and hosts the Lepanto enargite Au ore deposit, also controlled by the Lepanto fault. The Lepanto epithermal deposit is related to the underlying Far Southeast porphyry; the quartz-alunite alteration halo of Lepanto is contemporaneous with the ~1.4 Ma potassic alteration of the porphyry. There are also silicic-advanced argillic alteration patches ~600 m above the Far Southeast orebody at the present surface; these are interpreted to be perched alteration. There is no systematic mineralogical or textural zoning in the Lepanto lithocap that indicates direction to the intrusive source. Most surface samples of the lithocap contain less than 50 ppb Au, despite many being less than a few hundred meters from underground Cu-Au ore. This study found that several characteristics of the Lepanto lithocap change systematically with distance from the causative intrusion: The alunite absorption peak at ~1,480 nm in the short wavelength infrared (SWIR) spectrum shifts to higher wavelengths where the sample is closer to the intrusive center, due to higher Na and lower K content in the alunite; published experimental studies indicate that high Na/(Na + K) is related to higher formation temperature. High Ca alunite, including huangite, also occurs at locations proximal to the intrusive center. Alunite mineral composition analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) indicates that the Pb content decreases toward the intrusive center, whereas Sr, La, Sr/Pb, and La/Pb increase markedly. Whole-rock compositions, using only nonmineralized (taken as Cu <0.1wt % and Au <0.1 ppm) and alunite-bearing samples, show that Pb and Ag/Au, plus Hg and Ag, decrease toward the intrusive center, and Sr/Pb and La/Pb ratios increase. Normalizing whole-rock Pb to the (Na + K) molal content produces a proxy for the alunite mineral composition, and this ratio provides the same indications as the LA-ICP-MS analyses of alunite. The concealed Victoria epithermal veins consist of intermediate sulfidation mineralization on the southwest flank of the porphyry. The veins are not exposed, but their presence at depth is indicated by subtle alteration (illite or interstratified illite and/or smectite or smectite + pyrite) and geochemical (As, Se) anomalies at the surface. The anomalies are strongly dependent on erosion level; no anomalies were found where the surface is >~350 m above the upper extent of the veins. An airborne geophysics survey indicates that the Far Southeast orebody is associated with a wide zone of demagnetization due to extensive magnetite-destructive phyllic alteration. Such low magnetic anomalies on the margin of a large lithocap elsewhere may deserve att ntion. The directional indicators and mineralization signatures found in this study have the potential to indicate direction to the intrusive center during exploration of similar porphyryepithermal districts. ©2011 Society of Economic Geologists, Inc. Economic Geology.
Geochemical characteristics and structural setting of lithium–caesium–tantalum pegmatites of the Dorchap Dyke Swarm, northeast Victoria, Australia
- Authors: Hines, Benjamin , Turnbull, D. , Ashworth, Luisa , McKnight, Stafford
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 70, no. 6 (2023), p. 763-800
- Full Text:
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- Description: The Dorchap Dyke Swarm hosts the first recorded occurrence of lithium–caesium–tantalum (LCT) pegmatites in Victoria, Australia. Syn-orogenic emplacement of pegmatite dykes occurred along a northwest-trending shear system during the Benambran Orogeny. Pegmatites are derived from fractionated melt associated with the Mount Wills Granite, which is an S-type, peraluminous granite originating from supracrustal melting of Ordovician sedimentary sequences. A distinct, eastward-oriented fractionation trend across the Dorchap Dyke Swarm has highlighted a 20 × 8 km highly fractionated zone in the northeastern Dorchap Range, which includes spodumene- and petalite-bearing pegmatites. A distinct pattern of elemental enrichment (P > Cs > Be > Nb
High grade Au-Sb vein-type mineralisation at Fosterville
- Authors: Dowling, Kim , McKnight, Stafford , Kotsonis, Andrew
- Date: 2001
- Type: Text , Conference paper
- Relation: Paper presented at 3rd Conference on Developments in Victorian Geology and Mineralisation, Ballarat : 26th-27th April 2001
- Full Text: false
Hydrothermal insights into the deposition of invisible and visible gold within aresenopyrite
- Authors: Morey, A. , Tomkins, A. , Weinberg, R. , Bierlein, Frank , McKnight, Stafford , Davidson, G.
- Date: 2007
- Type: Text , Conference paper
- Relation: Proceedings of the Ninth Biennial SGA Meeting, Dublin 2007, 20th August, 2007 p. 781-784
- Full Text: false
- Description: By studying backscatter electron (BSE) micrographs, and the major- and trace-element geochemistry of gold bearing arsenopyrite from the late-Archaian Bardoc Tectonic Zone, Western Australia, this study helps constrain the hydrothermal conditions of gold deposition associated with this common ore mineral.
- Description: E1
- Description: 2003005489
Illite crystallinity and the b-spacing values of white micas and their implications for gold mineralisation in the Lachlan Orogen
- Authors: Wilson, C. , McKnight, Stafford , Dugdale, A. , Rawling, T. , Farrar, A. , McKenzie, M. , Melling, W.
- Date: 2009
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 56, no. 8 (2009), p. 1143-1164
- Full Text: false
- Reviewed:
- Description: Gold mineralisation in the Lachlan Orogen of western Victoria, is generally hosted in turbidites with very low-grade metamorphic assemblages. Metamorphic data from these turbidites are relatively rare because of the fine-grained nature of the pelitic component and lack of suitable assemblages for thermobarometric estimates. In this study, 'illite crystallinity' (Kubler Index) and b-lattice spacing measurements were carried out on white micas in metapelites, collected from near the inferred western margin of the Selwyn Block, as well as three exploration targets, in an attempt to relate thermal and barometric conditions to mineralisation. Higher-grade (epizone) metamorphic conditions are recorded in sequences west of the Whitelaw Fault and lower-grade (anchizone) metamorphic conditions to the east of the fault. The change from epizonal to anchizonal grade is abrupt, resolved to a distance of a few hundred metres. The b-spacing values change adjacent to the Muckleford Fault. This is due to rocks to the east being exhumed as the edge of the Selwyn Block moved westward during the Middle Devonian Tabberabberan Orogeny at 380Ma. We propose that the juxtaposition of rocks with contrasting thermal and barometric histories represents expression of the upper crustal location of the western margin of the Selwyn Block at the time of peak deformation, at about 440Ma, and this crustal structure controlled the distribution of the major quartz-vein-type gold deposits. The Middle Devonian orogenic activity (380Ma) was accompanied by the formation of disseminated gold deposits such as Fosterville. This represents a mineralising event that overprints the earlier gold deposits in a corridor at least 50km wide and to the west of the Whitelaw Fault, that parallels the margin of the Selwyn Block. The correlation between gold assays and 'illite crystallinity' results, from X-ray diffraction and from short-wave infrared-reflectance field-spectroscopy data, were ambiguous. Kubler Indices are not found to be effective in targeting of mineralisation as the values obtained from the alteration and the host-rock assemblages were similar and reflected the ambient P-T conditions at the time of mineralisation.
In vitro assessment of arsenic mobility in historical mine waste dust using simulated lung fluid
- Authors: Martin, Rachael , Dowling, Kim , Nankervis, Scott , Pearce, Dora , Florentine, Singarayer , McKnight, Stafford
- Date: 2018
- Type: Text , Journal article
- Relation: Environmental Geochemistry and Health Vol. 40, no. 3 (2018), p. 1037-1049
- Full Text: false
- Reviewed:
- Description: Exposure studies have linked arsenic (As) ingestion with disease in mining-affected populations; however, inhalation of mine waste dust as a pathway for pulmonary toxicity and systemic absorption has received limited attention. A biologically relevant extractant was used to assess the 24-h lung bioaccessibility of As in dust isolated from four distinct types of historical gold mine wastes common to regional Victoria, Australia. Mine waste particles less than 20 µm in size (PM20) were incubated in a simulated lung fluid containing a major surface-active component found in mammalian lungs, dipalmitoylphosphatidylcholine. The supernatants were extracted, and their As contents measured after 1, 2, 4, 8 and 24 h. The resultant As solubility profiles show rapid dissolution followed by a more modest increasing trend, with between 75 and 82% of the total 24-h bioaccessible As released within the first 8 h. These profiles are consistent with the solubility profile of scorodite, a secondary As-bearing phase detected by X-ray diffraction in one of the investigated waste materials. Compared with similar studies, the cumulative As concentrations released at the 24-h time point were extremely low (range 297 ± 6–3983 ± 396 µg L−1), representing between 0.020 ± 0.002 and 0.036 ± 0.003% of the total As in the PM20.
Leven Star deposit: An example of Middle to Late Devonian intrusion-related gold systems in the western Lachlan Orogen, Victoria
- Authors: Whittam, R. R. , Bierlein, Frank , McKnight, Stafford
- Date: 2006
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 53, no. 2 (2006), p. 343-362
- Full Text:
- Reviewed:
- Description: This study documents an example of atypical gold mineralisation in the central Victorian gold province of the western Lachlan Orogen, Australia. Unlike the vast majority of orogenic gold deposits in this region, the Leven Star deposit at Malmsbury is characterised by a disseminated-stockwork style of mineralisation, a close spatial and temporal association with post-tectonic felsic intrusions, complex alteration characteristics and a Au-As-Sb (±Bi-Te-Cu-Zn-Pb-Sn-W) ore assemblage. In contrast to orogenic-style, metamorphism-related gold mineralisation (ca 440 Ma), which pre-dated magmatism in the western Lachlan Orogen by tens of millions of years, ore formation in the Leven Star deposit was synchronous with, and is paragenetically younger than, Middle to Late Devonian (ca 370 Ma) magmatism. On the basis of these timing relationships, as well as whole-rock geochemistry, and structural, petrographic and fluid-inclusion data, it is suggested that the Leven Star deposit is not orogenic in character and instead should be classified as intrusion-related. © Geological Society of Australia.
- Description: C1
- Description: 2003001628
Mechano-chemical oxidation of arsenopyrite
- Authors: Koroznikova, Larissa , McKnight, Stafford , Veder, Jean-Peirre , Giri, Jason , Palaniandy, Samayamutthirian , Williams, Gordon
- Date: 2019
- Type: Text , Journal article
- Relation: Minerals Engineering Vol. 141, no. (2019), p. 1-7
- Full Text: false
- Reviewed:
- Description: This paper presents the results from the investigation of arsenopyrite oxidation via mechano-chemical activation, using a stirred mill. Water and hydrogen peroxide were chosen as the lixiviant and oxidant, respectively, and maintained at a relatively low temperature (50 °C). The milling media size, mill speed, slurry percent solids and amount of H2O2 added were all kept constant throughoust these experiments. The only operational variable for this investigation was the milling time, which results in increasing levels of specific energy provided by the mill. The products of activated arsenopyrite are characterised in terms of phase composition, particulate and structural characteristics, along with reactivity. Mechano-chemical activation of arsenopyrite under oxidizing conditions shows a maximum dissolution of around 9 wt% for iron and 7 wt% for arsenic after 2 h of milling. After 3 h of milling, the main phase present is found to be amorphous in nature.
Metamorphic style of the Tabberabbera zone, Lachlan Fold Belt
- Authors: Morand, Vincent J , McKnight, Stafford
- Date: 2006
- Type: Text , Conference paper
- Relation: Australian Earth Sciences Symposium, Melbourne 2/07/2006
- Full Text: false
- Description: 2003004226
Microencapsulation of alpha-Amylase by carrying out complex coacervation and drying in a single step using a novel three-fluid nozzle spray drying
- Authors: Jiang, Hao , Zhang, Min , McKnight, Stafford , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Drying Technology Vol. 31, no. 16 (December 2013 2013), p. 1901-1910
- Full Text: false
- Reviewed:
- Description: The aim of this research was to develop an enzyme encapsulation process in which both the complex coacervation and drying processes are combined into a single step. For this purpose, we used a novel three-fluid nozzle at the atomization step of spray drying. -Amylase as a model enzyme was encapsulated by coacervation in calcium (Ca) alginate and Ca-alginate+chitosan shell matrices and the powder was obtained in a single step through spray drying. The single-step process was compared to carrying out the complex coacervation and drying processes in two steps using freeze drying, in which -amylase was encapsulated by carrying out the complexation process in the above-mentioned shell matrices using the same three-fluid atomizer and collecting the coacervates, which were subsequently freeze dried. The results showed that the microcapsules obtained from the single-step encapsulation process (three-fluid nozzle spray drying) had smaller particle sizes, were less porous, and provided better enzyme stability compared to the microcapsules obtained by carrying out the complexation and drying in two steps and the single-step process was faster. It was observed that the egg-box structure was formed in both types of powder particles; however, the complexation with chitosan partially disrupted the formation of this structure. The three-fluid nozzle-based spray drying is a promising technology in which both the complex coacervation and drying processes can be carried out in a single step.
- Description: C1
Microencapsulation of flaxseed oil in flaxseed protein and flaxseed gum complex coacervates
- Authors: Kaushik, Pratibha , Dowling, Kim , McKnight, Stafford , Barrow, Colin , Adhikari, Benu
- Date: 2016
- Type: Text , Journal article
- Relation: Food Research International Vol. 86, no. (2016), p. 1-8
- Full Text: false
- Reviewed:
- Description: Flaxseed oil, a rich source of omega-3 fatty acids, was microencapsulated in a novel matrix formed by complex coacervation between flaxseed protein isolate (FPI) and flaxseed gum (FG). This matrix was crosslinking with glutaraldehyde. Liquid microcapsules with three core (oil)-to-wall ratios (1:2, 1:3 and 1:4) were prepared and spray-dried or freeze-dried to produce powders. The microencapsulation efficiency, surface oil, morphology and oxidative stability of these microcapsules were determined. The spray-dried solid microcapsules had higher oil microencapsulation efficiency, lower surface oil content, smoother surface morphology and higher oxidation stability than the freeze-dried microcapsules. The highest microencapsulation efficiency obtained in spray-dried microcapsules was 87% with a surface oil of 2.78% at core-to-wall ratio 1:4 and oil load 20%. The oxidation stability obtained from spray-dried microcapsules at core-to-wall ratio of 1:4 was nearly double that of the unencapsulated flaxseed oil. © 2016 Elsevier Ltd.