Julius Kruttschnitt Mineral Research Center

Brisbane, Australia

Julius Kruttschnitt Mineral Research Center

Brisbane, Australia
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Bonfils B.,Julius Kruttschnitt Mineral Research Center
International Journal of Mineral Processing | Year: 2017

The detailed understanding of rock impact breakage represents a key challenge in the development of comminution models. Semi-empirical properties have been used to describe ore competencies, such as the JK breakage index t10 and Axb values, but are not able to estimate mechanical properties linked with particle fracture. The information derived from particle breakage testing on impact load cells devices, have the potential estimates such mechanical properties. However, the large intrinsic natural variability of rocks and ores composition and shape makes the results difficult to analyze and difficult to compare against each other for particles with similar properties. This study investigates the effect of rock shape on the variability of the impact breakage test conducted on impact load cells. The test methodology was modified to account for shape when testing regular shape samples such as drilled mini-cores, with objective of reducing the intrinsic variability caused by rock shape, using a controlled shaped sample. The promising results open new avenues for establishing relationships between rock composition, texture and mechanical properties. © 2017 Elsevier B.V.

Leigh G.M.,Julius Kruttschnitt Mineral Research Center
IEEE Transactions on Signal Processing | Year: 2013

New algorithms for the continuous wavelet transform are developed that are easy to apply, each consisting of a single-pass finite impulse response (FIR) filter, and several times faster than the fastest existing algorithms. The single-pass filter, named WT-FIR-1, is made possible by applying constraint equations to least-squares estimation of filter coefficients, which removes the need for separate low-pass and high-pass filters. Non-dyadic two-scale relations are developed and it is shown that filters based on them can work more efficiently than dyadic ones. Example applications to the Mexican hat wavelet are presented. © 2012 IEEE.

Ozer C.E.,Julius Kruttschnitt Mineral Research Center
Minerals Engineering | Year: 2016

A convenient apparatus for density fractionating finely sized coal samples has been developed. It is inexpensive compared with the apparatus used in current methods. The apparatus and method are described, and a possible use of the test results in conjunction with ash content of coal matter is discussed. © 2015 Elsevier Ltd. All rights reserved.

Shi F.,Julius Kruttschnitt Mineral Research Center | Zuo W.,Julius Kruttschnitt Mineral Research Center
Fuel | Year: 2014

An improved method for coal breakage characterisation has been developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC). Part 1 of this paper presents the breakage testing method and results, Part 2 gives a breakage model that determines the energy-size reduction relationship for multi-components of particle size and coal density, and Part 3 demonstrates the applications of the model for HGI predictions and coal breakage simulations. The new method incorporates hardware for a fine particle breakage characterisation test, the JKFBC (JK Fine-particle Breakage Characteriser), a device modified from the standard HGI mill, which has a precision torquemeter installed to record energy utilisation during the experiments. Distinguished from the traditional HGI test, which is based on a single particle size with a single energy, the new characterisation test offers the flexibility to grind coal particles at various sizes, or various densities, or indeed (various components) with a range of energy levels. Energy consumption during the grinding was recorded. Using an Australian and a Chinese coal sample collected from power stations, this paper demonstrates the effects of particle size and density on coal breakage, and elucidates the deficiencies associated with the traditional HGI test. © 2013 Elsevier Ltd. All rights reserved.

A new method was developed to infer the HGI (Hardgrove Grindability Index) values from the product fineness indicator, t10, predicted by the multi-component breakage model. A total of 41 sets of JKFBC (JK Fine-particle Breakage Characteriser) tests, on coals from Australia and China, plus ores containing various minerals and a clinker, were used to validate this method. The JKFBC and the multi-component breakage model have the potential to improve or replace the traditional HGI test. A new coal grindability index can be generated from the multi-component model parameters. As the major error sources associated with the traditional HGI test have been removed in this new approach, superior repeatability and reproducibility can be expected. More work is recommended in this area to validate this novel approach and to identify its limitations. Simulations were conducted by employing the multi-component breakage model to demonstrate the effects of particle size and density on pulverised fuel (PF) grinding; to troubleshoot the PF production problems related to the coal properties; and to elucidate the observed trend of the non-linear phenomenon of the HGI effect on the PF milling capacity; whereby a 10 unit reduction in HGI from 50 to 40 requires four times more energy than a 10 unit HGI reduction from 90 to 80 in order to achieve the same PF production rate. © 2013 Elsevier Ltd. All rights reserved.

Shi F.,Julius Kruttschnitt Mineral Research Center
Fuel | Year: 2014

A multi-component breakage model has been developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC) to describe the energy-size reduction in relation to particle size and density for coal breakage characterisation. The model takes the following form: t10=M/(RD/ RDmin)c ·{1-exp[-fmat·x·E]}. The model incorporates four parameters and fits 60 JKFBC (JK Fine-particle Breakage Characteriser) test data for each of the Australian coal and Chinese coal samples, with R2 = 0.982 and 0.978 respectively. The multi-component model can be switched into a single component model by setting c = 0. A set of tn-family of curves for coals ground in the JKFBC are presented. It was found that the data from various particle sizes and densities of the two coal samples, collected from the Australian and Chinese power stations, all fall on similar tn-curve trend lines. These tn-family of curves can be used in the multi-component model to estimate the product size distribution from the predicted t10 values. A procedure has been developed to calibrate the multi-component model with seven tests based on a combination of various particle sizes, coal densities and grinding energy levels, using the JKFBC device. Over 100 sets of data have been used to validate the calibration procedure. © 2013 Elsevier Ltd. All rights reserved.

Peng Y.,University of Queensland | Bradshaw D.,Julius Kruttschnitt Mineral Research Center
Minerals Engineering | Year: 2012

In this work, the flotation of ultrafine pentlandite and its separation from lizardite in de-ionized water, and bore water of high ionic strength were studied. In de-ionized water, the flotation separation was poor due to low pentlandite recovery and high lizardite entrainment. However, bore water increased pentlandite flotation recovery while reducing lizardite entrainment. The possible mechanisms responsible for the improved flotation separation in bore water were investigated by electrokinetic studies, Scanning Electronic Microscopy (SEM) analysis and settling tests. It was found that the reduction of electrical double layer forces between particles in bore water might mitigate the coating of lizardite particles on pentlandite surfaces resulting in the improved pentlandite flotation. The reduction of electrical double layer forces might also induce the aggregation of lizardite particles and therefore enhance lizardite rejection. This study provides a new direction to address slime coating and high gangue entrainment in ultrafine mineral flotation by electrolytes. © 2012 Elsevier Ltd. All rights reserved.

Farrokhpay S.,Julius Kruttschnitt Mineral Research Center
Applied Spectroscopy Reviews | Year: 2012

This article presents a review of the published articles related to the novel application of spectroscopy and microscopy methods in paint and coatings quality evaluation. Traditional and simple techniques have been used in paint and coating industry for many years and proven to be effective. However, the paint and coating industry faces new formulations with nontraditional applications. Therefore, the industry needs to adjust itself with the current sophisticated production and testing methods. There are a number of modern microscopy and spectroscopy techniques that can be utilized in the paint and coating industry for a better understanding of the product quality and/or application performance. This, in particular, is highly applicable in modern and nontraditional applications such as nanotechnology and smart coatings. Though importance of spectroscopy and microscopy methods is being increasingly recognized in the industry, there is no current comprehensive review available to highlight the need for novel application of these techniques in surface coatings evaluations. Copyright © Taylor & Francis Group, LLC.

Rizmanoski V.,Julius Kruttschnitt Mineral Research Center
Minerals Engineering | Year: 2011

It has been shown that very short exposures to a high level of microwave power lead to reductions in ore strength. In this paper, the influence of modulated microwave power on copper ore breakage has been investigated. This approach to power delivery is applied to ascertain whether the strength of porphyry copper ore can be reduced with lower average modulated power levels than using continuous power. Changes in resistance to breakage of the treated and untreated ore were quantified by comparative drop weight tests. Mineralogical investigation for the ore was carried out with the Mineral Liberation Analyser (MLA) for surface identification of minerals and X-ray tomography for volumetric analysis. The comparative drop weight tests showed that material treated for 5 s at 5 kW of modulated power was weaker than untreated material. However, for this particular low grade ore, the degree of breakage which was achieved could be achieved with substantially less mechanical energy. It is possible that by using much higher level of microwave power, better liberation might be achieved than using conventional methods. © 2011 Elsevier Ltd. All rights reserved.

Lotter N.O.,Xstrata Process Support | Bradshaw D.J.,Julius Kruttschnitt Mineral Research Center
Minerals Engineering | Year: 2010

Mixtures of collectors have been widely used for many years in sulphide flotation, and a range of performance benefits have been reported for many different systems. The combinations of collector types have varied, as have the ratios that have been used. Synergistic effects have been obtained (greater than the sum of the parts) and in some cases the mechanisms of this improved behaviour have been identified. These benefits have been attributed to increased carrying capacity of the froth phase, faster kinetics, and more successful recovery of middling or coarse particles. It is the interaction between the various components of the mixed collector system, rather than the individual main effects, that dominate the performance benefits. The process benefits include increased paymetal recoveries and grades - as well as increased rates of recovery whilst using lower dosages of reagents. Various mechanisms have been reported and are discussed. These have been shown to affect different composition/liberation classes and sizes of mineral particles. In recent years, automated quantitative mineralogy and surface analysis technology such as ToF-SIMS have enabled the development of better information, to establish what aspect of the process has been affected. This has been successful mostly for use in a diagnostic capacity. Candidate selection for the mixed collector suite is presently based on experience and contextual knowledge. Predictive properties from these systems are a desirable future goal. Currently optimum combinations are preferably identified experimentally at laboratory scale prior to any plant trial. It is recommended that such laboratory work be performed using a factorial design with replicates and quality controls, such as may be delivered from High-Confidence Flotation Testing. The purpose of this paper is to summarise and review current theory and practice in the usage of mixtures of collectors in sulphide flotation - both in the application and in research in order to develop insights and guidelines to develop a methodology for use in a predictive capacity. A case study demonstrating this approach will be published at a later date. © 2010 Elsevier Ltd. All rights reserved.

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