Geometallurgy: driving innovation in the mining value chain

This is the author accepted manuscript. The final version is available from AusIMM via the linkGeometallurgy is a discipline which seeks to improve the sustainability of the extraction of metals and minerals by promoting the smarter use of non-renewable resources, better energy efficiency and greater use of renewable energy. To achieve these goals, development of innovative technologies and approaches are being developed along the entire commodity value chain, starting with exploration and extraction and extending to reuse and recycling. This paper discusses the geometallurgy of industrial minerals with special emphasis on kaolin, a versatile industrial mineral applied in ceramics, paper, paint, plastics, rubber, pharmaceuticals, cosmetics, ink, sealants, adhesives, sanitaryware, glass fibre, toothpaste, animal feed, etc.. Aspects of kaolin extraction in southwest UK are analysed from a geometallurgical perspective. While geometallurgy already features in kaolin extraction, its role can be significantly expanded by combining advanced in-pit characterisation and orebody modelling with integrated planning and control of the refining and calcination process. This paper highlights the importance of innovation in realising the full potential of geometallurgy.The author would like to thank Daniel Goodman (Jacobs UK Ltd), Aurela Shtiza (IMA Europe), and Imerys Minerals Ltd for supporting this study. The author acknowledges funding as part of the Sustainable Technologies for Calcined Industrial Minerals (STOICISM, www.stoicism.eu) project funded by the European Union’s 7th Framework Programme (FP7/2007-2013) under grant agreement number 310645

Modelling the structural controls of primary kaolinite formation

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.An abundance of kaolinite was formed within the St Austell granite pluton of Cornwall, southwest England, by the hydrous dissolution of feldspar crystals. The permeability of Cornish granites is low and alteration acts pervasively from discontinuity features, with montmorillonite recognised as an intermediate assemblage in partially kaolinised material. Structural features allowed fluids to channel through the impermeable granite and pervade deep into the rock. Areas of high structural control are hypothesised to link well with areas of advanced alteration. As kaolinisation results in a loss of competence, we present a method of utilising discontinuity orientations from nearby unaltered granites alongside the local tectonic history to calculate strain rates and delineate a discrete fracture network. Simulation of the discrete fracture network is demonstrated through a case study at Higher Moor, where kaolinite is actively extracted from a pit. Reconciliation of fracture connectivity and permeability against measured subsurface data show that higher values of modelled properties match with advanced kaolinisation observed in the field. This suggests that the technique may be applicable across various industries and disciplinesWe acknowledge and are grateful for use of the Move Software Suite granted by Midland Valley's Academic Software Initiative. We would also like to thank Imerys Minerals Ltd. for the contribution of drill data and field access. Richard Hooper and Chris Yeomans are thanked for their help and advice. We thank two anonymous reviewers for their helpful comments and suggestions. One of the authors (HG) would like to acknowledge funding as part of the Sustainable Technologies for Calcined Industrial Minerals (STOICISM) project funded by the European Union's seventh Framework Program (FP7/2007–2013) under grant agreement number 310645

Plastics recycling and sampling

This is the author accepted manuscript. The final version is available from AusIMM via the link in this record.This contribution examines the effect of feedstock sampling before the sorting stage of PET bottle recycling. Batches of waste PET bottles may contain non-PET bottles which need to be removed by sorting. Any residual presence of PVC is detrimental for the quality of products manufactured from recycled PET. The maximum tolerated concentration of PVC in cleaned PET is extremely low, which places high demands on the recovery of PVC achieved by sorting. To be confident of attaining the desired PET quality after sorting, acceptance sampling of truckloads of PET bottles may take place prior to sorting. It is shown that accounting for sampling uncertainty requires that the sorting process achieves a consistently high recovery of PVC bottles

Sequencing of ore columns for planning of large underground mines

This is the final version. Available from Wroclaw University of Science and Technology via the DOI in this record. Block caving is an underground mining technique which extracts ore from the base, rather than from the top, of typically massive deposits. Mining infrastructure is developed below the deposit before extraction commences. A network of tunnels provides access to a collection of drawpoints from which ore is mucked and hauled. With large deposits, not all drawpoints are developed simultaneously and the opening of drawpoints is sequenced to facilitate orderly extraction of ore columns above drawpoints. Sequencing fixes the initiation point for the entire block cave, or a part of it, as well as identifying the direction of cave advancement. The sequence of opening drawpoints influences the mine economics and is an integral aspect of planning a block cave mine. This paper discusses the optimisation of sequencing based on the net present value associated with extraction over the life-of-mine. It is shown that the maximum attainable net present value is obtained by a sequence in which ore columns are ranked in descending order of value. If significant variation of grade is present inside columns, an iterative procedure is given which corrects the sequence which yields the maximum net present value. The sequence with maximum net present value may not be practical or attractive from a caving perspective. Systematic design of sequences which permit orderly development of a block cave is discussed. To provide context, the net present value obtained from these feasible sequences is compared with the maximum attainable net present value. It is shown that the best feasible sequences in terms of net present value are preferentially initiated in zones with columns of high-grade ore.Rio Tinto Technical Services Lt

Sequencing of ore columns for planning of large underground mines

This is the final version. Available on open access from Wroclaw University of Science and Technology via the DOI in this recordBlock caving is an underground mining technique which extracts ore from the base, rather than from the top, of typically massive deposits. Mining infrastructure is developed below the deposit before extraction commences. A network of tunnels provides access to a collection of drawpoints from which ore is mucked and hauled. With large deposits, not all drawpoints are developed simultaneously and the opening of drawpoints is sequenced to facilitate orderly extraction of ore columns above drawpoints. Sequencing fixes the initiation point for the entire block cave, or a part of it, as well as identifying the direction of cave advancement. The sequence of opening drawpoints influences the mine economics and is an integral aspect of planning a block cave mine. This paper discusses the optimisation of sequencing based on the net present value associated with extraction over the life-of-mine. It is shown that the maximum attainable net present value is obtained by a sequence in which ore columns are ranked in descending order of value. If significant variation of grade is present inside columns, an iterative procedure is given which corrects the sequence which yields the maximum net present value. The sequence with maximum net present value may not be practical or attractive from a caving perspective. Systematic design of sequences which permit orderly development of a block cave is discussed. To provide context, the net present value obtained from these feasible sequences is compared with the maximum attainable net present value. It is shown that the best feasible sequences in terms of net present value are preferentially initiated in zones with columns of high-grade ore.Rio Tinto Technical Services Lt

Selective leaching of copper from near infrared sensor-based preconcentrated copper ores

This is the final version. Available on open access from Wroclaw University of Science and Technology via the DOI in this recordCopper oxide ore was pre-concentrated using near infrared sensor-based method and classified as product, middling and waste. The product and middling fractions were leached with ammonium chloride reagent. The effect of temperature, ammonium chloride concentration, solid-liquid ratio, stirring speed and particle size experimental variables were investigated. Mineralogical and chemical analysis of the ore fractions indicated that copper content was in accordance with the preconcentration strategy, with the product having a higher concentration than the middling and waste. The rate of copper extraction was found to be higher in the product than in the middling sample which further supports the near infrared classification, QEMSCAN®, X-ray diffraction, SEM mineralogical and X-ray florescence and Inductively coupled plasma Mass spectrometry chemical data. It was revealed that the leaching rate increases with increasing ammonium chloride concentration, temperature and decreasing ore particle size, stirring speed and solid-liquid ratio. Analysis of the experimental data by shrinking core model indicated that the dissolution kinetics follow the heterogeneous reaction model for the chemical control mechanism where the activation energies of 45.9 kJ/mol and 47.5 kJ/mol for product and middling fractions respectively were obtained. Characterization of the residue obtained at optimum leaching condition with X-ray diffraction suggests that copper was selectively leached when compared to the profile of the raw ore. The trace levels of metals associated with abundant X-ray diffraction profiles of residue found in the leachate further confirm the selective leaching process.Natural Environment Research Council (NERC

Discerning mineral association in the near infrared region for ore sorting

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The preconcentration or early rejection of gangue minerals in mineral processing operations is investigated using sorting, based on interpretation of near infrared sensor data collected from ore particles. The success of sorting depends on the distribution of minerals between particles, the arrangement or association of minerals within particles and the ability of near infrared to distinguish relevant minerals. This paper considers minerals association, using common alteration minerals found in a hydrothermally-formed copper ore, with sensitivity in the near infrared region. The selected NIR-active minerals were arranged along the view of NIR line scanner to stimulate adjacent natural minerals association. It was found that spectral dominance may depend on minerals near infrared sensitivity and or the position of a mineral along the NIR scanner line of view. Analysis also revealed that only free occurring waste mineral spectra can be targeted for discrimination as tailings. Where spectra appeared mixed, such spectra are best considered products.The Nigerian Government through the academic support scheme of the Tertiary Education Trust Fund (TETFund) of Nigeria and the management of the Nasarawa State University, Keffi are acknowledged for providing financial support for this research

Smart Recovery of Cobalt as a By-Product of Primary Copper Extraction: Geometallurgical ore-type classification using FTIR spectroscopy

Cobalt is a transition metal whose physico-chemical properties make it a critical component in many tech applications, including high-strength alloys, magnets, rechargeable batteries used in electric cars, wind energy turbines, and energy storage systems. Cobalt is recovered as a by-product from extraction of nickel and/or copper ore. The largest cobalt output is derived from copper sediment-hosted deposits in the Democratic Republic of Congo (DRC). Efficient co-recovery of cobalt is challenging because the ratios of copper and cobalt within the deposit is variable. In addition, differences in mineralogy and texture are observed which imply that a fixed extraction process is not optimal for the entire deposit. In order to stabilise the mining value chain and optimize plant performance, comprehensive understanding of ore properties and geometallurgical factors which influence process performance is mandatory. Relevant ore properties depend on the processing options available (gravity, flotation, leaching) and the type of product considered (cobalt salt or metal). These properties can, in turn, be used to classify the resources by defining ore-types which are suited for a given processing route. To obtain insight into the spatial distribution of relevant properties and build a 3D geometallurgical model, it is necessary to develop techniques that have potential to measure properties rapidly and, preferably, within the mine. We have investigated the application of portable Fourier Transformed InfraRed (FTIR) to quantify the modal mineralogy of drillcore samples which are representative of the sulphide zone within a DRC Cu-Co deposit. Results were validated using QEMSCAN analysis. Prediction of gangue and target mineral grades was achieved using multivariate data analysis of the FTIR spectra through Partial Least Squares Regression. It is shown that the modal mineralogy obtained from FTIR can be used to classify ore types according to the type of copper-cobalt mineralization, copper-cobalt mineral grades, and gangue mineralogy. When the resulting geometallurgical model of the deposit is integrated into the mine planning process, the recovery of copper and cobalt can be optimized

Development of a strategy and interpretation of the NIR spectra for application in automated sorting

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThe Near Infrared (NIR) spectroscopy is a novel technique that can be used for early identification and separation of minerals from unwanted gangue during ore sorting. In this research, the potential of near infrared sensors for application in automated sorting was investigated on a copper-gold ore sample. The ore contains a substantial amount of carbonaceous material which results in excessive acid consumption in the subsequent leaching process during copper extraction. To classify this unwanted gangue material (carbonate) from the valuable metal (copper), a strategy to identify and distinguish the ore according to copper and carbonate content was developed. The near infrared spectra were measured on the surface of ore particles and characteristic absorption features were observed at a longer wavelength ranging from 2000 nm to 2405 nm. The results were then correlated with the chemical and mineralogical composition of the ore determined using X-Ray fluorescence and X-Ray diffraction equipments respectively. The near infrared spectra showed distinct characteristic absorption features for carbonate rich particles that distinguished these from copper bearing particles, which are fairly featureless at longer wavelengths. Combined interpretation of spectral features and chemical and mineralogical data indicates that near infrared-based sorting has potential for this type of ore.The authors wish to thank the Zambian government and the Copperbelt University management for the financial support towards this research

World production and possible recovery of cobalt from the Kupferschiefer stratiform copper ore

This is the final version. Available from EDP Sciences via the DOI in this record.Cobalt is recognized as a strategic metal and also E-tech element, which is crucial for worlds development. An increasing demand for cobalt forces for searching of new resources that could be explored in European countries. There are many examples of cobalt recoveries, mostly from laterite and sulphide deposits. However, the accurate choice of the technology depends on many factors. The Kupferschiefer stratiform copper ore located in Poland is the biggest deposit of cobalt in Europe. Although KGHM Polska Miedz S.A. recovers many precious metals from this ore, cobalt is not recovered yet. This metal occurs as an accompanying element, mostly in the form of cobaltite (CaAsS), with the average content of 50-80 g/Mg. In this paper a possible recovery of cobalt from the Kupferschiefer ore, with the use of hydrometallurgical methods, was investigated.Polish Statutory Research Gran