Efficient measurement methods for comminution properties are an important prerequisite for testing the variability of an ore deposit within the geometallurgical context. This involves the investigation of effects of mineralogy and mineral texture on the breakage of mineral particles. Breakage properties of mineral particles are crucial for the liberations of minerals and the energy required for that. For process optimization and control purposes, comminution indices are often used to map the variation of processing properties of an entire ore body (e.g. Bond work index). Within the geometallurgical approach this information is then taken up when modelling the process with varying feed properties. The main focus of this thesis work has been to develop a comprehensive geometallurgical testing framework, the Geometallurgical Comminution Test (GCT), which allows the time and cost efficient measurement of grinding indices and their linkage to mineralogical parameters (e.g. modal mineralogy or mineral texture, mineral liberation). In this context a small-scale grindability test has been developed that allows estimating the Bond work index from single pass grinding tests using small amounts of sample material. Verification of the evaluation method and validation was done with different mineral systems. For selected samples the mineral liberation distribution was investigated using automated mineralogy. By transferring the energy-size reduction relation to energy – liberation relation new term liberability has been established. As part of the experimental investigations, mineralogical parameters and mineral texture information were used for predicting breakage and liberation properties. Patterns for describing the breakage phenomena were established for a set of iron oxide ore samples. The determined breakage patterns indicated that the specific rate of mineral breakage slows down when reaching the grain size of mineral particles, thus allowing maximizing mineral liberation significantly without wasting mechanical energy. / CAMM

Zinkgruvan is a Pb-Zn-Ag deposit located in south-central Sweden, owned and operated by Lundin Mining. The ore is beneficiated by a collective-selective flotation circuit, recovering both galena and sphalerite in a bulk rougher-scavenger flotation stage and later on separating them into two final products. Opportunities for increase in zinc recovery in the bulk rougher scavenger flotation stage have been identified as the plant is relying on natural Pb-activation to process the ore. Process mineralogical tools were used to characterize four different orebodies from Zinkgruvan (Burkland, Borta Bakom, Nygruvan and Sävsjön) and evaluate the metallurgical performance for flotation and magnetic separation, following a geometallurgical approach to better understand and predict the behavior of such ore types in processing plant. The first hypothesis in this thesis is that by addition of copper sulfate and increased collector dosage, Zn recovery will be improved without being detrimental to galena flotation. Results demonstrated that there is a significant increase in Zn recovery by further increasing collector dosage and copper-activating the flotation pulp in the scavenger stage. For instance, an increase in zinc recovery up to 16% has been achieved after addition of copper sulfate. Galena is readily floatable while sphalerite takes longer to be recovered. In addition, iron sulfides take longer to be recovered and, after addition of copper sulfate, there was an increase in iron sulfide recovery. The amount of iron sulfides reporting to the concentrate should still not be a problem to the plant. Most of the Fe in the concentrate is still coming from the sphalerite lattice. However, it might be that some orebodies coming into production in the near future have higher amounts of pyrrhotite, which might be a problem. Therefore, magnetic separation methods have been tested to remove pyrrhotite from the bulk ore. The second hypothesis is that the high Fe content in the concentrate might be due to the presence of iron sulfides, in which case they could be selectively removed by magnetic separation. XRD analyses demonstrated that Sävsjön is a highly variable orebody, and that its high Fe content varies with the location inside the orebody, being caused by either iron sulfide or iron oxide minerals. Both monoclinic and hexagonal pyrrhotite have been observed. Davis Tube could remove monoclinic pyrrhotite but it was very inefficient when dealing with hexagonal pyrrhotite. WHIMS, on the other hand, performed well for both types of pyrrhotite. When applying Davis Tube on Sävsjön OLD feed, a concentrate with up to 52.3% pyrrhotite is achieved, at a recovery of 35.32%. However, sphalerite is also reporting to the magnetic concentrate, which would generate Zn losses for the overall process. Zinc losses were up to 15.3% when the highest field strength was applied. Therefore, the applicability of magnetic separation for Zinkgruvan ore must be further evaluated.

In recent years, automated mineralogy has become an essential tool in geometallurgy. Automated mineralogical tools allow the acquisition of mineralogical and liberation data of ore particles in a sample. These particle data can then be used further for particle-based mineral processing simulation in the context of geometallurgy. However, most automated mineralogical tools currently in application are based on two-dimensional (2D) microscopy analysis, which are subject to stereological error when analyzing three-dimensional(3D) object such as ore particles. Recent advancements in X-ray microcomputed tomography (µCT) have indicated great potential of such system to be the next automated mineralogical tool. µCT's main advantage lies on its ability in monitoring 3D internal structure of the ore at resolutions down to few microns, eliminating stereological error obtained from 2D analysis. Aided with the continuous developments of computing capability of 3D data, it is only the question of time that µCT system becomes an interesting alternative in automated mineralogy system. This study aims to evaluate the potential of implementing µCT as an automated mineralogical tool in the context of geometallurgy. First, a brief introduction about the role of automated mineralogy in geometallurgy is presented. Then, the development of µCT system to become an automated mineralogical tool in the context of geometallurgy andprocess mineralogy is discussed (Paper 1). The discussion also reviews the available data analysis methods in extracting ore properties (size, mineralogy, texture) from the 3D µCT image (Paper 2). Based on the review, it was found that the main challenge inperforming µCT analysis of ore samples is the difficulties associated to the segmentation of the mineral phases in the dataset. This challenge is adressed through the implementation of machine learning techniques using Scanning Electron Microscope (SEM) data as a reference to differentiate the mineral phases in the µCT dataset (Paper 3).

A Mina de Santa Rita, situada no complexo máfico-ultramáfico Fazenda Mirabela, é uma intrusão máfica-ultramáfica, mineralizada a sulfetos de níquel e cobre, situada no sudeste do Estado da Bahia, município de Itagibá. Esse depósito é composto por rochas de idade Paleoproterozóica, metamorfizadas em fácies granulito. Os sulfetos de níquel e cobre ocorrem disseminados e, preferencialmente, associados a harzburgitos, olivina ortopiroxenitos e ortopiroxenitos. O minério é composto por uma grande variedade de Mg-silicatos, sendo que o níquel ocorre essencialmente como pentlandita nos peridotitos, além de se apresentar como elemento menor em silicatos e espinélios em rochas mais máficas. Informações de processo demonstram a impossibilidade de se estabelecer uma correlação robusta entre a composição química do minério e seu comportamento na etapa de beneficiamento mineral. Desta forma, o conhecimento da variabilidade mineralógica no depósito é de fundamental importância para o planejamento de lavra e processamento mineral. Mais de 300 amostras do plano de mineração de curto prazo (2013-2017) relativas a intervalos de furos de sondagem considerados no estudo de viabilidade econômica (período de 1985-2004) foram agrupadas em domínios mineralógicos, utilizando a análise estatística multivariada de dados de difração de raios X (DRX-AEM). Dezessete domínios mineralógicos inicialmente definidos são essencialmente diferenciados com base na presença e conteúdos relativos dos principais minerais de ganga: serpentina, olivina e piroxênio. Amostras representativas dos principais domínios mineralógicos, pré-definidos por DRX-AEM, foram submetidas a estudos de caracterização mineralógica de detalhe por análise de imagens (MEV-MLA). Os resultados indicam que os grupos com composições mais peridotíticas e/ou carbonáticas, com maiores conteúdos de serpentina, apresentam menor tempo de moagem para atingir P95 igual a 0,15 mm; maior alteração dos grãos de pentlandita; maior parcela de total de níquel associado a silicatos; menor grau de liberação dos sulfetos; e maior quantidade de sulfetos abaixo de 10 ?m, em relação aos grupos de composição mais piroxenítica. / The Santa Rita mine, located in the mafic-ultramafic complex Fazenda Mirabela, is a mafic-ultramafic intrusion mineralized to nickel and copper sulphides located in the southeast of Bahia state, Itagibá municipality. The nickel sulphide deposit comprises a portion of a mafic-ultramafic layered complex under granulite metamorphism facies. Disseminated Ni and Cu sulphides form a stratiform body parallel to the lithostratigraphic contacts extending upwards essentially from the harzburgite unit and through the olivine orthopyroxenite unit. The nickel content is mainly associated to pentlandite in peridotitic rocks but also enriched in silicates and spinels in mafic rocks (dunites). Industrial plant benchmark data have shown the unfeasibility of establishing a strong relation between the ore chemical composition and its behavior in the mineral beneficiation process. Therefore, the knowledge of the mineralogical variability in the deposit is crucial for mine planning and mineral/metallurgical processing. More than 300 samples from drill core samples from the feasibility studies (period of 1985-2004) included in the short-term mining plan (2013-2017) were clustered into geological domains applying multivariate statistical analysis (MSA) of X-ray diffraction data (XRD). Results discriminated seventeen initial mineralogical domains considering the content of major gangue minerals: serpentine, olivine and pyroxene. Representative samples of the main mineralogical domains pre-defined by XRD-MSA ore-types were later subject to sieve size analysis followed by detailed mineralogical studies by automated SEM image analysis (MLA). The results indicate that groups with more peridotite and / or carbonatic compositions, with higher content of serpentine, have less time of grinding to reach P95 equal to 0,15 mm; high level of pentlandite alteration; greater portion of nickel associated into silicates; lower sulphides liberation degree; and a higher amount of sulphides below 10 ?m; in relation to the most pyroxenic composition groups.

This work presents two innovative ways to evaluate mining projects. The first is the application of a Technological Model in a copper-gold mine and the second is a decision making model to evaluate the benefit of semi-mobile in pit crusher and conveyor alternatives during the early stages of mining projects. In order to improve the process and to maximize the production and/or value of a mining project, there needs to be an integration of the geology, the mine plan, the processing and the geometallurgy data. In order to accomplish this, a new methodology is proposed for the creation of a technological model. This model can be interpreted as the consolidation of the different models required for a better understanding of the geological and technical information of the deposit. This concept was developed and applied at a copper and gold mine site located in Brazil. Based on the evaluation of different blasting and mill productivity scenarios through a pit-to-plant approach, it was possible to obtain operational short-term gains such as a 10.7% increase in the plant production rate and a 2.2% increase in the crusher\'s feed rate with little or no capital investment. Another important issue faced by mining companies is related to material handling. A significant cost in the operating budget of most mining operations arises from purchasing and maintaining haulage trucks. Recently, in-pit crushing and conveying (IPCC) has been subject to research because of its potential to reduce haulage costs. A decision-making model was created to identify early on in a project whether or not the semi-mobile IPCC (SMIPCC) is an appropriate alternative to the conventional truck haulage based on the loading and hauling approaches. The method is based on cost analysis and the evaluation of environmental impacts, being successfully tested at an existing open-pit mine, where the results indicated that the IPCC was the most cost-effective option for the operation. Although the IPCC\'s initial CAPEX was 60% higher than the conventional approach, the IPCC\'s OPEX was 43% lower, resulting in a 28% reduction of the life-of-mine net present cost (NPC). / Este trabalho apresenta duas maneiras inovadoras de avaliar projetos de mineração. A primeira é a elaboração e aplicação do modelo tecnológico para uma mina de cobre e ouro já a segunda refere-se à confecção de um modelo de tomada de decisão a ser usado para a análise dos benefícios de aplicação de britagem semimóvel em cava. Para melhorar os processos e maximizar a produção e/ou o valor de um projeto de mineração, existe a necessidade de integração dos dados de geologia, planejamento de mina, beneficiamento e geometalurgia. Com esse foco, uma nova metodologia foi proposta para a criação do modelo tecnológico. Este modelo pode ser interpretado como a consolidação dos diferentes modelos necessários para uma melhor compreensão das informações geológicas e técnicas do depósito. Este conceito foi desenvolvido e aplicado em uma mina de cobre de ouro localizada no Brasil. Com base na avaliação de diferentes cenários de perfuração e desmonte de rochas e de produtividade do moinho, usando uma abordagem de mina-usina, foi possível obter ganhos operacionais de curto prazo, tais como um aumento de 10,7% na taxa de produção de usina e um aumento de 2,2% na taxa de alimentação da britagem com pouco ou nenhum investimento de capital. Uma outra questão relevante para empresas de mineração é o transporte de material. Um custo significativo na maioria das minas surge da compra e manutenção de caminhões de transporte. A britagem em cava e correias (IPCC em inglês) vem sido avaliada em diversos casos devido ao seu potencial para reduzir os custos de transporte. Neste estudo, um modelo de tomada de decisão foi criado para identificar em etapas iniciais de um projeto os benefícios de aplicação de IPCC semimóvel (SMIPCC em inglês) em comparação com método convencional, exclusivamente por caminhões. O método baseia-se na análise de custos e na avaliação de impactos ambientais testado em uma mina a céu aberto, onde os resultados indicaram que o SMIPCC foi a opção mais econômica para a operação. Embora o investimento inicial do IPCC foi 60% maior do que a abordagem convencional, o custo operacional do IPCC foi 43% menor, resultando em uma redução de 28% do custo total a valor presente.

A Mina de Santa Rita, situada no complexo máfico-ultramáfico Fazenda Mirabela, é uma intrusão máfica-ultramáfica, mineralizada a sulfetos de níquel e cobre, situada no sudeste do Estado da Bahia, município de Itagibá. Esse depósito é composto por rochas de idade Paleoproterozóica, metamorfizadas em fácies granulito. Os sulfetos de níquel e cobre ocorrem disseminados e, preferencialmente, associados a harzburgitos, olivina ortopiroxenitos e ortopiroxenitos. O minério é composto por uma grande variedade de Mg-silicatos, sendo que o níquel ocorre essencialmente como pentlandita nos peridotitos, além de se apresentar como elemento menor em silicatos e espinélios em rochas mais máficas. Informações de processo demonstram a impossibilidade de se estabelecer uma correlação robusta entre a composição química do minério e seu comportamento na etapa de beneficiamento mineral. Desta forma, o conhecimento da variabilidade mineralógica no depósito é de fundamental importância para o planejamento de lavra e processamento mineral. Mais de 300 amostras do plano de mineração de curto prazo (2013-2017) relativas a intervalos de furos de sondagem considerados no estudo de viabilidade econômica (período de 1985-2004) foram agrupadas em domínios mineralógicos, utilizando a análise estatística multivariada de dados de difração de raios X (DRX-AEM). Dezessete domínios mineralógicos inicialmente definidos são essencialmente diferenciados com base na presença e conteúdos relativos dos principais minerais de ganga: serpentina, olivina e piroxênio. Amostras representativas dos principais domínios mineralógicos, pré-definidos por DRX-AEM, foram submetidas a estudos de caracterização mineralógica de detalhe por análise de imagens (MEV-MLA). Os resultados indicam que os grupos com composições mais peridotíticas e/ou carbonáticas, com maiores conteúdos de serpentina, apresentam menor tempo de moagem para atingir P95 igual a 0,15 mm; maior alteração dos grãos de pentlandita; maior parcela de total de níquel associado a silicatos; menor grau de liberação dos sulfetos; e maior quantidade de sulfetos abaixo de 10 ?m, em relação aos grupos de composição mais piroxenítica. / The Santa Rita mine, located in the mafic-ultramafic complex Fazenda Mirabela, is a mafic-ultramafic intrusion mineralized to nickel and copper sulphides located in the southeast of Bahia state, Itagibá municipality. The nickel sulphide deposit comprises a portion of a mafic-ultramafic layered complex under granulite metamorphism facies. Disseminated Ni and Cu sulphides form a stratiform body parallel to the lithostratigraphic contacts extending upwards essentially from the harzburgite unit and through the olivine orthopyroxenite unit. The nickel content is mainly associated to pentlandite in peridotitic rocks but also enriched in silicates and spinels in mafic rocks (dunites). Industrial plant benchmark data have shown the unfeasibility of establishing a strong relation between the ore chemical composition and its behavior in the mineral beneficiation process. Therefore, the knowledge of the mineralogical variability in the deposit is crucial for mine planning and mineral/metallurgical processing. More than 300 samples from drill core samples from the feasibility studies (period of 1985-2004) included in the short-term mining plan (2013-2017) were clustered into geological domains applying multivariate statistical analysis (MSA) of X-ray diffraction data (XRD). Results discriminated seventeen initial mineralogical domains considering the content of major gangue minerals: serpentine, olivine and pyroxene. Representative samples of the main mineralogical domains pre-defined by XRD-MSA ore-types were later subject to sieve size analysis followed by detailed mineralogical studies by automated SEM image analysis (MLA). The results indicate that groups with more peridotite and / or carbonatic compositions, with higher content of serpentine, have less time of grinding to reach P95 equal to 0,15 mm; high level of pentlandite alteration; greater portion of nickel associated into silicates; lower sulphides liberation degree; and a higher amount of sulphides below 10 ?m; in relation to the most pyroxenic composition groups.

In a particle based geometallurgical model, the behavior of the particles can be used for forecast the products and quantify the performance of the different ore types within a deposit. The particle tracking is an algorithm developed by Lamberg and Vianna 2007 whose aim is to balance the liberation data in a mineral processing circuit composed by several processing units. Currently, this tool is being developed for the HSC Chemistry software by Outotec.The objective of this study is to understand and evaluate the particle tracking algorithm in a geometallurgical test for iron ore. To achieve this objective, the liberation data is balanced in a Davis tube test circuit. A total of 13 samples from Leveäniemi iron ore were process in a Davis tube circuit.The magnetite is the main mineral in the Leveäniemi iron ore samples. Its high recovery in the Davis tube circuit along with the V, Ti and Mn suggest that these elements are present in the magnetite lattice. These penalty elements in the iron concentrates cannot be avoided at the stage of mineral concentrations.The washing effect of the Davis tubes controlled by the rotational and longitudinal agitation of the tube perturb the particles agglomeration between the pole tips of the electromagnet. A higher agitation frequency and amplitude will wash away most of the gangue minerals and also fine grained magnetite.In this work, the particle tracking is depicted and implemented in a magnetic separation circuit for high liberated material. The liberation data was balanced in a way that the particle classes can be followed through circuit and their recoveries can be calculated. Nevertheless, the algorithm requires further validation and analysis of its limitations in terms of resolution and reproducibility.

Most of the high-grade ores have been depleted globally, thus the effective processing of the low-grade and complex ores require a comprehensive mineral characterization through the process mineralogy/ geometallurgical approaches. 30-70 % of the total energy consumption in mining comes from the comminution step in mineral processing. This study, is aimed to investigate how different mineral domains in Lappberget, Garpenberg affect the grinding energy and throughput of an autogenous grinding mill (AG) and how blending different mineralogical domains will have an effect on throughput. The results were obtained through automated mineralogy using a Zeiss Sigma 300 VP at the QANTMIN scanning electron microscope (SEM) laboratory (Luleå University of Technology) and an in-house grindability test developed by Boliden Mineral AB. There is approximately a multiple of three times differences in the amount of energy consumption and throughput between the hardest and softest mineralogical domains. This difference is attributed to mineral composition of the individual domains and mineral characteristics. Blending different samples indicate that a higher throughput can be achieved and one possible hypothesis is that the harder minerals act as grinding media.

Lithium represents one of the strategic elements for the rest of the 21st century due to its increasing demand in technological applications. Therefore, new efforts should be focused on the optimization of mineral characterization processes, which link the ore properties with its behaviour during downstream processes. These efforts should result in reducing operational risks and increasing resources utilization. The methodology presented in this study is based on the application of several classification techniques, aiming the mineral and textural characterization of two spodumene pegmatite deposits within the Keliber Lithium Project. Twelve textural classes have been proposed for the textual classification of the ore, which have been defined through the recognition of the main mineral features at macro- and micro-scale. The textural classification was performed through the application of drill core logging and scanning electron microscopy. Six classes are proposed to describe the characteristics of the spodumene ore. Six additional classes describe the main properties of the rocks surrounding the ore zone. Image analysis was implemented for the generation of mineral maps and the subsequent quantification of spodumene and Li2O within the analysed drill core images. The image segmentation process was executed in Fiji-ImageJ and is based on eight mineral classes and a set of seven feature extraction procedures. Thus, quantification of spodumene and Li2O is estimated by textural class. Hyperspectral images were used as a reference for assessing the estimations made through images analysis. A machine learning model in Weka allowed forecasting the behaviour of the twelve textural classes during spodumene flotation. This model is fed by metallurgical data from previous flotation tests and uses Random Forest classifier. The proposed methodology serves as an inexpensive but powerful approach for the complete textural characterization of the ore at Keliber Lithium Project. It provides information about: (1) mineral features at different scales, (2) spatial distribution of textures within the pegmatite body, (3) quantification of spodumene and Li2O within the drill cores and (4) processing response of each textural class. However, its application requires wide knowledge and expertise in the mineralogy of the studied deposits. / <p>Thesis Presentation.</p><p>Textural and Mineralogical Characterization of Li-pegmatite Deposit: Using Microanalytical and Image Analysis to Link Micro and Macro Properties of Spodumene in Drill Cores.  Keliber Lithium Project, Finland.</p><p></p>

Driven by the need to use mineral resources more sustainably, and the increasing complexity of ore deposits still available for commercial exploitation, the acquisition of quantitative data on mineralogy and microfabric has become an important need in the execution of exploration and geometallurgical test programmes. Hyperspectral drill-core scanning has the potential to be an excellent tool for providing such data in a fast, non- destructive and reproducible manner. However, there is a distinct lack of integrated methodologies to make use of these data through-out the exploration and mining chain. This thesis presents a first framework for the use of hyperspectral drill-core scanning as a pillar in exploration and geometallurgical programmes. This is achieved through the development of methods for (1) the automated mapping of alteration minerals and assemblages, (2) the extraction of quantitative mineralogical data with high resolution over the drill-cores, (3) the evaluation of the suitability of hyperspectral sensors for the pre-concentration of ores and (4) the use of hyperspectral drill- core imaging as a basis for geometallurgical domain definition and the population of these domains with mineralogical and microfabric information.:Introduction Materials and methods Assessment of alteration mineralogy and vein types using hyperspectral data Hyperspectral imaging for quasi-quantitative mineralogical studies Hyperspectral sensors for ore beneficiation 3D integration of hyperspectral data for deposit modelling Concluding remarks References