| 1. |
- Guntoro, Pratama Istiadi, 1993-, et al.
(författare)
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X-ray Microcomputed Tomography (µCT) for Mineral Characterization : A Review of Data Analysis Methods
- 2019
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Ingår i: Minerals. - Basel, Switzerland : MDPI. - 2075-163X. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- The main advantage of X-ray microcomputed tomography (µCT) as a non-destructive imaging tool lies in its ability to analyze the three-dimensional (3D) interior of a sample, therefore eliminating the stereological error exhibited in conventional two-dimensional (2D) image analysis. Coupled with the correct data analysis methods, µCT allows extraction of textural and mineralogical information from ore samples. This study provides a comprehensive overview on the available and potentially useful data analysis methods for processing 3D datasets acquired with laboratory µCT systems. Our study indicates that there is a rapid development of new techniques and algorithms capable of processing µCT datasets, but application of such techniques is often sample-specific. Several methods that have been successfully implemented for other similar materials (soils, aggregates, rocks) were also found to have the potential to be applied in mineral characterization. The main challenge in establishing a µCT system as a mineral characterization tool lies in the computational expenses of processing the large 3D dataset. Additionally, since most of the µCT dataset is based on the attenuation of the minerals, the presence of minerals with similar attenuations limits the capability of µCT in mineral segmentation. Further development on the data processing workflow is needed to accelerate the breakthrough of µCT as an analytical tool in mineral characterization.
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| 2. |
- Koch, Pierre-Henri, 1988-
(författare)
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A numerical study of the effects of microwave pre-treatment on value liberation from a zinc ore
- 2019
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Konferensbidrag (refereegranskat)abstract
- The extraction of mineral values from ore requires liberation followed by separation steps. Liberation is achieved by size reduction operations which are energy inefficient processes typically dominating the energy consumption in a mineral concentrator. As the grade of ore reserves declines, future viability of mineral operations will be determined by energy costs of comminution. The application of high power microwave energy to secondary crusher products has been suggested as a possible commercially viable thermal treatment method for reducing comminution energy and improving value mineral liberation. Recent studies have shown that microwave pre-treatment of coarse sphalerite ore particles (> 5mm) at specific microwave heating energies (1-3 kWh/t), induces microfractures and creates new crack surfaces. This suggests that subsequent crushing of these microwave treated particles could yield enhanced liberation. However, limited studies have been carried out investigating the mode of breakage and the extent of enhanced liberation in that case. The objective of this study is to develop numerical methods for quantifying the extent of enhanced liberation and mode of breakage in crushed microwave treated and untreated particles. Sphalerite ore particles representing small (-5+4.75) mm, medium (-16+9.5) mm, and large (-25+19) mm HPGR and cone crushed particles were microwave treated at specific energies between 1-3 kWh/t. Cracks in the ore particles before and after microwave treatment were analysed with QEMSCAN and numerical models of the measured particles (before and after microwave treatment) were developed in MATLAB. The propagation of random and nonrandom cracks was investigated by simulating comminution of the modelled treated and untreated particles. Results of this study demonstrate that the breakage mechanism and the liberation of valuable minerals from gangue in microwave treated and untreated particles is significantly different. This study contributes to the development of numerical tools to quantify crack propagation in heterogeneous ore particles.
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| 3. |
- Koch, Pierre-Henri, 1988-, et al.
(författare)
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Automated drill core mineralogical characterization method for texture classification and modal mineralogy estimation for geometallurgy
- 2019
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Ingår i: Minerals Engineering. - Amsterdam : Elsevier. - 0892-6875 .- 1872-9444. ; 136, s. 99-109
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Tidskriftsartikel (refereegranskat)abstract
- In geometallurgy, a process model operating at the mineral liberation level needs quantitative textural information about the ore. The utilization of this information within process modeling and simulation will increase the quality of the predictions.In this study, descriptors derived from color images and machine learning algorithms are used to group drill core intervals into textural classes and estimate mineral maps by automatic pixel classification. Different descriptors and classifiers are compared, based on their accuracy and capacity to be automated. Integration of the classifier approach with mineral processing simulation is also demonstrated. The quantification of textural information for mineral processing simulation introduced new tools towards an integrated information flow from the drill cores to a geometallurgical model.The approach has been verified by comparing traditional geological texture classification against the one obtained from automatic methods. The tested drill cores are sampled from a porphyry copper deposit located in Northern Sweden.
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| 4. |
- Koch, Pierre-Henri, 1988-
(författare)
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Computational methods and strategies for geometallurgy
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- At the interface of geology and mineral processing, geometallurgy is a powerful tool for enhancingresource efficiency. A spatial model that represents the ore body in terms ofmineralogyand physical properties is combined with a process model that describes the concentrationprocess. The performance of a given ore in the process is computed in terms of gradeand recovery of the mineral of interest in the concentrate, but also the presence of potentialpenalty elements and energy costs. The inclusion of ore performance indicators in a blockmodel yields a geometallurgical model that considers the variations in an ore body.Progress has been made in recent years to list and study different processing options interms of data requirements and implementation costs. While providing useful data, littleadvance was made to guide decision-making and to handle uncertainty. The objective has,therefore, been to develop, choose and validate computational methods that suggest optimaldecisions in the scope of geometallurgical strategies for an iron ore and a porphyry copperdeposit.The selected approach is based on an analysis of structure and regularity fromthe ore blockdown to the mineral grains. By selecting the appropriate mathematical tool for each scale,the dimension of the data is reduced and the different scales are then taken into account inmaking decisions. Methods introduced for dimension reduction include machine learningmodels, statistical models and spectral descriptors. The decision models rely on stochasticmulti-armed bandits which are a form of reinforcement learning. The presentation of thedifferent models proceeds by zooming in from coarse scale to fine scale then taking a stepback and analyze the implications. Data that was collected during sampling campaigns andindustrial plant surveys is used to design and verify the proposedmodels.iWith regard to the dimension reduction problem, results showed the method’s ability toclassify mineral textures and identify mineral phases with more than 90 percent accuracy onthe selected data sets of optical images and incorporate different physical properties into ageometallurgical ore type classification. Decision results showed that strategies in the case ofa feed grade control or when different ore types were identified, resulted in a twofold increaseof a reward function which is either Boolean (the product fulfills quality requirements ornot), or continuous (an economic objective). The cumulative value of the reward functionmeasured the optimality of a processing strategy. Quantitative methods were introduced toevaluate ore classification as well as geometallurgical strategies.The achieved results suggest the introduction of these computationalmethods in the practiceof geometallurgy. The increased knowledge of different ore type performances and appropriatemodels lead to optimal decisions for improved resource efficiency along the ore valuechain. This is achieved by bothmaximizing profit and decreasing environmental impact, forexample by choosing processing routes that minimize energy consumption.
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| 5. |
- Koch, Pierre-Henri, 1988-
(författare)
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Particle generation for geometallurgical process modeling
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A geometallurgical model is the combination of a spatial model representing an ore deposit and a process model representing the comminution and concentration steps in beneficiation. The process model itself usually consists of several unit models. Each of these unit models operates at a given level of detail in material characterization - from bulk chemical elements, elements by size, bulk minerals and minerals by size to the liberation level that introduces particles as the basic entity for simulation (Paper 1).In current state-of-the-art process simulation, few unit models are defined at the particle level because these models are complex to design at a more fundamental level of detail, liberation data is hard to measure accurately and large computational power is required to process the many particles in a flow sheet. Computational cost is a consequence of the intrinsic complexity of the unit models. Mineral liberation data depends on the quality of the sampling and the polishing, the settings and stability of the instrument and the processing of the data.This study introduces new tools to simulate a population of mineral particles based on intrinsic characteristics of the feed ore. Features are extracted at the meso-textural level (drill cores) (Paper 2), put in relation to their micro-textures before breakage and after breakage (Paper 3). The result is a population of mineral particles stored in a file format compatible to import into process simulation software. The results show that the approach is relevant and can be generalized towards new characterization methods.The theory of image representation, analysis and ore texture simulation is briefly introduced and linked to 1-point, 2-point, and multiple-point methods from spatial statistics. A breakage mechanism is presented as a cellular automaton. Experimental data and examples are taken from a copper-gold deposit with a chalcopyrite flotation circuit, an iron ore deposit with a magnetic separation process.This study is covering a part of a larger research program, PREP (Primary resource efficiency by enhanced prediction).
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| 6. |
- Koch, Pierre-Henri, 1988-, et al.
(författare)
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Sequential decision-making in mining and processing based on geometallurgical inputs
- 2020
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 149
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Tidskriftsartikel (refereegranskat)abstract
- Geometallurgy as a multi-disciplinary field has been applied at various levels in different operations. By linking the ore performance in mineral beneficiation processes to the ore block model, it supports estimating the value of a block before it is mined. Efforts in the classification of the ore into geometallurgical classes have led to a better understanding of the entire value chain. While classification provides a convenient tool for forecasting and visualization purposes, it simplifies the actual complexity of an ore body. In mining and process planning, sequential decisions are made to maximize an objective function or equivalently minimize a regret function. Using available information from geology or metallurgical test work, an optimal strategy can be found using tools from the machine learning community.In this study, a framework based on machine learning to maximize the use of such classifications for sequential decision-making is proposed. The concepts of reinforcement learning and bandit algorithms, offer powerful tools to explore and exploit different optimization strategies. In certain cases, theoretical guarantees about the performance of given methods can be obtained by regret bounds.Based on existing models of a porphyry copper deposit and an iron ore deposit, this study presents a methodology and different available algorithms to maximize an objective function that depends on a high number of variables and in the presence of noise or uncertainty in the models. Different numerical experiments provide a basis for discussion and comparison to human decisions. The hypotheses relative to each algorithm are discussed in relation to the mineral processing models.
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| 7. |
- Koch, Pierre-Henri, 1988-, et al.
(författare)
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Texture-based liberation models for comminution
- 2017
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Ingår i: Konferens i Mineralteknik 2017. - Luleå. ; , s. 83-96
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The relation between breakage mechanisms and liberation is critical in mineral processing. Recent studies underline the importance of texture in liberation. This study reviews relevant liberation models and proposes a new method for generating particles using image processing algorithms. One new texture simulation method and its relevance for liberation simulation is also introduced.
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| 8. |
- Lishchuk, Viktor, 1984-, et al.
(författare)
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Geometallurgical characterisation of Leveäniemi iron ore : Unlocking the patterns
- 2019
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 131, s. 325-335
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Tidskriftsartikel (refereegranskat)abstract
- As part of a geometallurgical program for the Leveänimei iron ore mine, the Davis tube was used as proxy to classify ore types, predict iron recoveries in wet low-intensity magnetic separation (WLIMS), and to estimate liberation of mixed particles. The study was conducted by testing 13 iron ore samples with a Davis tube and a laboratory WLIMS. Ore feed was studied for modal mineralogy and liberation distribution with Automated Scanning Electron Microscopy. Data analyses to detect the patterns and data dependencies were done with multivariate statistics: principal component analysis, and projection to latent structures regression. Results show that a simple index (XLTU) based on mass pull (yield) in the Davis tube is capable of easy classification of magnetite ores. Using Davis tube mass pull and iron recovery, together with iron and Satmagan head grades may predict iron recovery in WLIMS. Also, the variability in Fe-oxides liberation pattern for magnetite semi-massive ores can be explained with the chemical composition of the Davis tube concentrate. It is concluded that the Davis tube test is better used only for marginal ores, since iron oxide minerals tend to be fully liberated in high-grade magnetite massive ores after grinding. The developed models may be used in populating a production block model.
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| 9. |
- Lishchuk, Viktor, 1984-, et al.
(författare)
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Towards integrated geometallurgical approach : Critical review of current practices and future trends
- 2020
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 145
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Forskningsöversikt (refereegranskat)abstract
- Geometallurgy has become an important tool for mitigating production risks and improving economic performance in the modern mining industry. Multiple definitions and visions of geometallurgy have been proposed during the last decades. Most of them define geometallurgy as a bridge between geology and mineral processing. Such a definition is rather confusing since process mineralogy claims to be such “bridge” too. Therefore, the main objective of the present paper is to provide a broad image of geometallurgy covering planning, executing and evaluation of geometallurgical programs. Such a vision of geometallurgy was developed within a research project PREP, which was aimed at “resource effective mineral processing”. PREP is a holistic geometallurgical approach independent of deposit type. The approach differentiates geometallurgical programs based on the complexity of the problem and the desirable outcome. Particular attention was paid to the planning of the geometallurgical programs, data management, and new tools development. The practical usage of the approach was tested with three case studies: iron-apatite ore, VMS, and Cu porphyry deposits. Some examples of applying geometallurgy for the iron-apatite ore are shown in this paper. The result, the guidelines on planning, executing and evaluating a geometallurgical program, are given in this paper.
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| 10. |
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