Forbes C.,University of Adelaide |
Giles D.,University of Adelaide |
Freeman H.,OZ Minerals Ltd. |
Sawyer M.,OZ Minerals Ltd. |
Normington V.,University of Adelaide
Journal of Geochemical Exploration | Year: 2015
Light rare earth elements (LREEs) are commonly enriched within iron oxide-copper-gold (IOCG) deposits within the Gawler Craton, South Australia. The LREEs are host within a number of phases including monazite, which is a resistate phase that can withstand processes of physical transport and weathering without significant chemical alteration. Recognition of this elevated LREE signature within rocks that have been transported away from mineralised zones can therefore be used as a geochemical vector towards potential IOCG mineralisation.In the northern Gawler Craton, South Australia, monazite occurs within basement rocks within and proximal to the Prominent Hill IOCG deposit. These basement rocks have been physically transported and dispersed during glacial activity subsequent to the mineralisation event, and redeposited in the cover sequence as a glacial diamictite. Here we show that the hydrothermal monazite within the mineralised zone has a characteristic geochemical signature, and that this signature has been preserved within monazite grains within the overlying glacial diamictite. The hydrothermal monazite is characteristically enriched in La and Ce, and depleted in Y and Th. A chemical criterion for exploration is derived. Monazite chemistry showing concentrations of La + Ce > 63. wt.% and Y and Th <. 1. wt.% is considered compelling. Concentrations of 57.5. wt.%. <. La + Ce. <. 63. wt.% are considered interesting, and compositions of La + Ce. <. 57.5. wt.% are considered background.Using the assumption that all light rare earth elements in the cover sequence are host within monazite, this mineral chemistry signature can be recognised in whole rock geochemistry. Data showing La > 75. ppm and Ce > 155. ppm is considered anomalous. Data that also shows (La + Ce):Y ratios between 10:1 and 30:1 and (La + Ce):Th ratios between 16:1 and 32:1 is considered interesting. Ratios of (La + Ce):Y and (La + Ce):Th greater than 30:1 and 32:1 respectively are considered compelling. In the northern Gawler Craton, the scale of the footprint associated with the anomalous whole rock geochemical signature characteristic of Prominent Hill-style IOCG mineralisation is 2-3 times larger than the orebody itself. Dispersion of this signature is related to glacial processes and palaeotopography. This chemical criteria may potentially be used as a geochemical vectoring method towards Prominent Hill-style IOCG mineralisation, and may be applicable to exploration for other IOCG deposits within the Gawler Craton and further afield. © 2015 Elsevier B.V. Source
Whincup P.R.,OZ Minerals Ltd.
Transactions of the Institutions of Mining and Metallurgy, Section C: Mineral Processing and Extractive Metallurgy | Year: 2010
This paper presents guidelines for studies required for the development of mineral processing facilities from initial feasibility studies through to commissioning. Mining project schedule and cost overruns can often be attributed to inadequate metallurgical testwork, engineering and cost estimating leading up to commitment to the project. In some cases this may result from lack of understanding of, and commitment by the project proponent to, the requisite metallurgical and engineering studies during the development stages. Guidelines for metallurgical testwork, process development, engineering and estimating requirements for each stage of precommitment studies are described together with those for the engineering phase. © 2010 Maney Publishing. Source
Smith N.R.A.,University of Tasmania |
Smith N.R.A.,OZ Minerals Ltd. |
Reading A.M.,University of Tasmania |
Asten M.W.,Monash University |
Funk C.W.,OZ Minerals Ltd.
Geophysics | Year: 2013
We constrain the depth and seismic structure of stiff sediment cover overlying a prospective basement terrane using a passive seismic technique which uses surface wave energy from microtremor (also known as ambient seismic energy or seismic noise). This may be applied to mineral exploration under cover to decrease the inherent ambiguity in modeling potential field data for exploration targeting. We use data from arrays of portable broadband seismometers, processed using both the multimode spatially averaged coherency (MMSPAC) method and the horizontal to vertical spectral ratio (HVSR) method, to produce profiles of seismic velocity structure along a 12-km transect.We have developed field protocols to ensure consistent acquisition of high-quality data in near-mine and remote locations and a variety of ground conditions. Awavefield approaching the theoretical ideal for MMSPAC processing is created by combining the energy content of an off-road vehicle, driven around the seismometer array, and ambient sources. We found that this combination results in significantly higher-quality MMSPAC waveforms in comparison with that obtained using ambient energy alone. Under ideal conditions, a theoretical maximum depth of investigation of 600 m can be achieved with a hexagonal sensor array with 50-m radius and MMSPAC and HVSR. The modeling procedure we employ is sensitive to layer thicknesses of ±5%. A high-velocity layer in the sediment package reduces the sensitivity to deeper structure. This can limit the modeling of underlying layers but may be addressed by detailed analysis of the HVSR peaks. Microtremor recordings including off-road vehicle noise, combined with the MMSPAC and HVSR processing techniques, may therefore be used to constrain sediment structure and depth to basement in a cost-effective and efficient method that could contribute greatly to future mineral exploration under cover. © 2013 Society of Exploration Geophysicists. Source
Lombardi J.,OZ Minerals Ltd. |
Muhamad N.,OZ Minerals Ltd. |
Weidenbach M.,OZ Minerals Ltd.
METPLANT 2011 - Metallurgical Plant Design and Operating Strategies | Year: 2011
OZ Minerals' Prominent Hill copper-gold concentrator is located 130 kilometres south east of the town of Coober Pedy in the Gawler Craton of South Australia. The concentrator was built in 2008 and commenced commercial production in early 2009. The Prominent Hill concentrator is comprised of a conventional grinding and flotation processing plant with a 9.6Mtpa ore throughput capacity. The flotation circuit includes six rougher cells, an IsaMill for regrinding the rougher concentrate and a Jameson cell heading up the three stage conventional cell cleaner circuit. In total there are four level controllers in the rougher train and ten level controllers in the cleaning circuit for eighteen cells. Generic proportional - integral and derivative (PID) control used on the level controllers alone propagated any disturbances downstream in the circuit that were generated from the grinding circuit, hoppers, between cells and interconnected banks of cells, having a negative impact on plant performance. To better control such disturbances, Float Star level stabiliser was selected for installation on the flotation circuit to account for the interaction between the cells. Multivariable control was also installed on the five concentrate hoppers to maintain consistent feed to the cells and to the IsaMill. An additional area identified for optimisation in the flotation circuit was the mass pull rate from the rougher cells. Float Star flow optimiser was selected to be installed subsequent to the Float Star level stabiliser. This allowed for a unified, consistent and optimal approach to running the rougher circuit. This paper describes the improvement in the stabilisation of the circuit achieved by the Float Star level stabiliser by using the interaction matrix between cell level controllers and the results and benefits of implementing the Float Star flow optimiser on the rougher train. Source