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Melbourne, Australia

Clinton B.,CSIRO | Warden A.C.,CSIRO | Haboury S.,CSIRO | Easton C.J.,Australian National University | And 5 more authors.
Biocatalysis and Biotransformation | Year: 2011

Strobilurin fungicides are some of the most heavily used antifungal chemicals in agriculture. However, little is known of their fate in the environment. We have identified bacteria that slowly transform strobilurin fungicides via hydrolysis of a methyl ester group in the toxophore, rendering them non-fungicidal. A carboxypeptidase (subtilisin Carlsberg) was found to have this activity, albeit with low specific activity (2.4 × 10 -2 nmol s -1 mg -1), and to possess specificity towards an analog of the fungicidal isomer of commercial strobilurins. Substrate-docking studies using the known structure for subtilisin Carlsberg revealed a plausible explanation for both the activity and isomer specificity of this class of hydrolase. These findings suggest that the promiscuous strobilurin methyl esterase activity of the subtilisin-like carboxypeptidases may have a role in the environmental fate of the strobilurin fungicides. © 2011 Informa UK, Ltd.

Remennikov A.M.,University of Wollongong | Mutton V.,Orica Australia Pty Ltd | Nimbalkar S.,University of Wollongong | Ren T.,University of Wollongong
International Journal of Rock Mechanics and Mining Sciences | Year: 2014

In the last fifteen years, Tekseal high yield foaming grout ore pass plugs that could later be easily removed, have been poured above chute maintenance areas providing protection from high energy rock impact and isolating workers from the hazard. Construction and removal methods will be briefly explained. Since it is not economically feasible to investigate the problem of ore pass plug impact response using full-scale experimental studies, this paper presents a combined four-stage approach that includes (1) laboratory testing to investigate the mechanical behaviour of the high-yield foaming grout; (2) high-precision impact testing of reduced-scale models of ore pass plugs; (3) high-fidelity physics-based numerical model calibration using experimental data; and (4) full-scale modelling of mine ore pass plugs using calibrated material models. To calibrate numerical models, three one-metre diameter steel pipes filled with Tekseal high yield foaming grout were tested with falling steel projectiles of different shapes. Impact tests provided data on the depth of penetration and size of the craters formed by the projectiles. Numerical models were calibrated by optimising the material parameters and modelling techniques to provide the best match with the experimental results. Full-scale numerical models of ore pass plugs were developed for typical ore pass dimensions and subjected to impact events by falling rock projectiles. The proposed approach has allowed investigating energy absorbing characteristics of ore pass plugs to further predict and increase understanding of their capacity to withstand high-speed impacts by large falling projectiles. © 2014 Elsevier Ltd.

Noy M.J.,Orica Australia Pty Ltd
Measurement and Analysis of Blast Fragmentation: Workshop Hosted by FRAGBLAST 10 - The 10th International Symposium on Rock Fragmentation by Blasting | Year: 2013

The development of measurement tools for assessing the rock fragmentation induced by blasting has always been constrained by the technology available at the time of development. As computer hardware and software improves, so too do the opportunities to adapt new and evolving technology to the measurement of blast results. One such area of technology that has developed in recent years is desktop photogrammetry. The author began applying photogrammetry (stereo imaging) to the measurement of rock fragmentation on a conveyor in 2005. This technology has recently been adapted for application on an operating face shovel for the fully automated measurement of the rock fragmentation in the muckpile. The use of synchronised stereo cameras for generation of live 3D images has a number of advantages for automated image segmentation algorithms and autonomous image triggering algorithms. This paper discusses the advantage this approach has over standard monocular based fragmentation measurement systems. Also discussed are some of the environmental aspects associated with mounting systems on a shovel. These factors include high vibration and shock, extreme temperatures and weather conditions, and high volumes of dust, all of which are prevalent on an operating shovel in remote and sometimes extreme locations. These environmental concerns have to be addressed to ensure the installed system survives for extended periods without the need for constant maintenance.

Buckley A.N.,University of New South Wales | Hope G.A.,Griffith University | Parker G.K.,Griffith University | Petrovic E.A.,Orica Australia Pty Ltd | Woods R.,Griffith University
International Journal of Mineral Processing | Year: 2016

The species adsorbed on Cu sulfide ore minerals from near neutral or alkaline solutions of the flotation collector 2-mercaptobenzothiazole (MBT) have been established by X-ray photoelectron spectroscopy (XPS). Previous XPS studies of the species adsorbed on chalcocite from very dilute solutions were extended to adsorption on air-exposed Cu metal, cuprite, chalcocite, covellite, cubanite, chalcopyrite, bornite and pyrite from more concentrated solutions to simulate processing of variably oxidised ores and slug addition of collector under plant conditions. It was found that even in alkaline solutions, HMBT adsorbed in addition to molecular CuMBT, (MBT)2 and chemisorbed MBT on Cu metal, CuI oxide or Cu sulfide minerals. For all Cu-containing surfaces conditioned in a collector solution of concentration higher than 10-5 M, adsorbed molecular (multilayer) CuMBT remained a minor species within the pH range investigated. For substantial collector coverage, when the concentration of adsorbed HMBT and (MBT)2 exceeded that of chemisorbed MBT and adsorbed CuMBT, the surface was not obviously hydrophobic. Neither a Cu nor Fe surface oxide layer was predominantly removed by the collector, but MBT chemisorption involved direct interaction with surface Cu atoms rather than via intermediate O atoms. There was strong evidence for a Cu-N interaction in bulk CuMBT, and hence in MBT chemisorbed on surface Cu atoms, in addition to the principal interaction through the MBT exocyclic S atom. It was concluded that adsorption of some multilayer MBT species on Cu sulfide ore minerals can be deleterious, and this should be taken into account when variably oxidised ores are being processed. © 2016 Elsevier B.V.

Esen S.,Orica Australia Pty Ltd
23rd International Mining Congress and Exhibition of Turkey, IMCET 2013 | Year: 2013

This paper reviews the blast fragmentation models developed to date and discusses the effects of the run-of-mine (ROM) fragmentation on the comminution circuits. The fragmentation model developed by the author is presented in detail. Its use in numerous mine-to-mill projects is briefly discussed. The fragmentation modelling framework is based on the combination of Kuz-Ram model to model the coarse end and an engineering approach to model the fines. It is well-known that the Kuz-Ram model underestimates the fines generated by blasting. The model is further validated by new data sets (actual sieving data). It is shown that the model is rather robust in estimating the fines generated by blasting. The mine-to-mill studies have shown that -10mm size generated by blasting can be considered a key performance index as this fraction has a significant effect on mill throughput. The mine sites have increased their powder factors significantly which resulted in mill throughput increases of 5 to 30%. Two case studies were presented as examples of the use of the fragmentation model in mine-to-mill projects. Some of the opportunities to further reduce the energy consumed by mining processes are also highlighted.

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