Sulphate-rich wastewater is an increasing concern for industries as LKAB. The water chemistry of the LKAB Kiruna water system is characterized by high alkalinity, high pH (pH 7.5-9.0) and high concentrations of chemical species and soluble minerals. The sulphate content in the water system of Kiruna is associated with the dissolution of calcium sulphate as anhydrite (CaSO4) and gypsum (CaSO4 2H2O). However, the high concentrations of sulphate in the effluents from the LKAB Kiruna operation are unique for iron ore mining.    The aim of the thesis was to study and evaluate the behavior of sulphate in the process water system of the Kiruna concentrator plants. This was done by laboratory grinding (leaching tests), equilibrium calculations with the HSC software and mass balancing of the concentrator KA3 in Kiruna. The highest concentrations of sulphate have been detected in the process water of KA3, hence the focus has been on KA3 regarding sampling, evaluation and comparison. Water treatment technologies for sulphate and the effect of process water on ore processing have not been included in this project.   The laboratory grinding was done using process water and ore from the concentrator KA3. During the experimental work with laboratory grinding the parameters pH, temperature and operating times for primary- and secondary grinding, respectively, were varied. The observations from the experimental work were further confirmed by equilibrium calculations and mass balancing. The following conclusions were drawn.     Anhydrite/gypsum is not leached from the ore during ore processing with process water having concentrations of sulphate already close to the saturation point at approximately 1800 mg/L. If the process water is diluted with water with lower sulphate content, e.g. mine water or a diluted return water from the pond system (e.g. during spring flood), anhydrite/gypsum in ore will be dissolved until the sulphate concentration reaches the saturation point. The ionic strength of the process water controls the saturation point and thus the sulphate concentration. Leaching of anhydrite/gypsum in saturated process water, with respect to sulphate, is not affected by grinding time or adjusted conditions in the process water, such as temperature or pH value.    For further work, it is recommended to investigate the behavior of sulphate in the tailings pond system to increase knowledge of the overall behavior in the water system. In addition, a similar investigation of the behavior of uranium in the process water is recommended in order to face future environmental standards.

The Swedish mining and minerals sector is one of the most prominent greenhouse gas emitters in the country. At the same time, it also provides Sweden and other nations with vast amounts of important metals and minerals, which are not easily replaced. However, in light of the increasing urgency to reduce global greenhouse gas concentrations, it is imperative that the combustion of fossil fuels is decreased. This quantitative case study uses a document review and interviews to investigate the prerequisites and technical potential for decarbonising the Dannemora iron ore mine in eastern Sweden. Furthermore, a comparative life cycle inventory based on methods from the Greenhouse Gas Protocol is performed in order to calculate potential savings of both energy and greenhouse gases from exchanging conventional underground mining equipment with more sustainable alternatives. Results show that emissions from underground activities in the Dannemora mine could potentially be reduced by up to 90 %, and energy consumption by up to 64 %. It was however also shown that no viable emission-free explosives currently exist that could safely replace conventional alternatives. Further research needs to be conducted in order to investigate the effects of Scope 3 emissions from the production of battery electric mining vehicles, as this would have an effect on overall GHG and energy savings.

No description available.

What kinetic and thermodynamic characteristics are established in a melt of hydrogen-reduced iron ore pellets? The pellets contain self-fluxing slag components which upon melting form an initial slag. Refining capabilities of this slag, such as dephosphorization power, are investigated in a lab-scale vertical furnace. Understanding the initial slag and the reactions taking place when hydrogen-reduced iron ore pellets melt is important for future optimization of ingoing raw materials as well as industry scale process design. A sample of either crushed hydrogen-reduced iron ore pellets or a powder mixture representative of iron ore pellets in terms of composition was melted in a lab-scale vertical furnace. The sample was lowered into the argon atmosphere furnace which had a temperature of 1600°. The sample was kept inside a magnesia crucible with a molybdenum loosely-fitted lid. The purpose of the lid was to fix the oxygen partial pressure. The reduction degree of the pellets or corresponding powder mixture as well as the total melting times were varied. XRF and OES analysis were employed to find the composition of the slag and metal phases, respectively. SEM analysis was employed to investigate phases present in the slag. Comparison of melted iron ore pellets and corresponding powder mixture show that powder can be employed to represent reduced iron ore pellets accurately. It was found that reduction degree strongly impacts both phosphorus and vanadium distributions as well as the types of phases formed in the slag fraction. During melting, almost all of the Vanadium and most of the Phosphorus content goes to the slag fraction. At lower reduction degrees, dephosphorization is greater; however, the Phosphorus content in the steel is still quite high at 130 ppm or higher. Modification to the amount and/or composition of the self-fluxing slag is suggested to reach lower levels of phosphorus in the steel. / Vilka kinetiska och termodynamiska egenskaper skapas i en smälta av vätgasreducerade järnmalmspellets? Pellets innehåller självflussande slaggkomponenter som vid smältning bildar en initial slagg. Slaggens raffineringsförmåga, till exempel fosforreningsförmåga, undersöks i laboratorieskala. För framtida optimering av ingående råvaror såväl som industriellskalig processdesign är det viktigt att förstå den initiala slaggen samt de reaktioner som äger rum vid nedsmältning av vätgasreducerade järnmalmspellets. Ett prov av antingen krossade vätgasreducerade järnmalmspellets eller en pulverblandning som är representativ för järnmalmspellets med avseende på sammansättning smältes ned i en laboratorieskalig vertikal ugn. Ugnen hade en argonatmosfär och temperatur på 1600°C då provet sänktes ner i ugnen för smältning. En magnesiumoxiddegel med ett löst inpassat molybdenlock användes som behållare för provet under nedsmältningen. Syftet med locket var att kontrollera syrgaspartialtrycket. Reduktionsgraden av pellets eller motsvarande pulverblandning såväl som de totala smältningstiderna varierades. XRF och OES mätverktyg användes för att undersöka sammansättning av slagg- och metallfraktionerna. SEM analys användes för att identifiera närvarande faser i slaggfraktionen. Jämförelse av nedsmälta vätgasreducerade järnmalmspellets med motsvarande pulverblandning visar att de två är representativa av varandra till stor grad. Resultaten visar på att reduktionsgraden påverkar starkt både fosfor- och vanadinfördelningarna samt faserna som bildas i slaggfraktionen. Vid smältning går nästan all mängd vanadin och majoriteten av fosfor till slaggfraktionen. Vid lägre reduktionsgrader är fosforreningen bättre. Fosforhalten i stålet är relativt hög och har ett värde på 130 ppm eller högre för samtliga prover. Ändring av mängden och/eller sammansättning av den självflussande slaggen rekommenderas för att nå lägre nivåer av fosfor i stålet.

Este trabalho consiste no estudo da obtenção de aglomerados autorredutores na forma de briquetes a frio tratados termicamente, utilizando minério de ferro e carvão fóssil como matérias-primas. Esta promissora tecnologia tem como premissa a utilização da termo-plasticidade do carvão fóssil para conferir resistência e promover a auto-aglomeração. A obtenção de briquetes dá-se através de três etapas: condicionamento da mistura, briquetagem a frio e tratamento térmico. Os finos de carvão e minério são misturados e homogeneizados. A mistura, então, passa por processo de briquetagem a frio para compactação, promove o aumento de contato entre as partículas de carvão e minério. Finalmente tratamento térmico é realizado para obter a forma de um corpo sólido e coeso de auto-aglomerado autorredutor. O objetivo deste trabalho é determinar as melhores condições de obtenção de briquetes através do estudo de variáveis ao longo do processo de fabricação, utilizando a resistência mecânica como parâmetro. As variáveis estudadas são: granulometria do carvão, envelhecimento do carvão, percentual de carvão na mistura, adição de aglomerantes, pressão de compactação na briquetagem e temperatura de tratamento térmico. Os resultados obtidos neste estudo indicam que estas variáveis afetam significativamente a resistência mecânica. Utilizando-se o carvão Chipanga, o melhor resultado de resistência à compressão foi de 19,82 Mpa. Foram consideradas as seguintes condições de fabricação: mistura na proporção de 75:25 (% em massa) de minério para carvão Chipanga, o carvão continha finos inferiores à 0,075 mm, sem a adição de aglomerantes, e o tratamento térmico foi realizado na temperatura de máxima fluidez do carvão. Além disto, foi observado que as partículas de minério de ferro foram concentradas nas regiões periféricas do briquete após tratamento térmico, e que o envelhecimento do carvão afeta negativamente a propriedade de termo-plasticidade. / This work is focused in the study of obtaining self-reducing cold briquettes of agglomerates, by using iron ore and coal as raw materials. This promising technology has its foundation on the thermo plasticity of coal to manage high mechanical resistance when it is compared with self-reducing pellets. Three steps mainly describes how to obtaining briquettes: mixture, cold briquetting and heat treatment. Fines of raw material are mixed and cold briquetting process results in a compact mixture. This might lead to closer contact between particles of iron ore and coal. Finally, heat treatment is performed to achieve a cohesive body and solid shape containing self-reducing agglomerated. The main purpose of this job is to comprehend the fundamentals on how to obtain self-reducing cold briquettes of agglomerated carbon and iron, by understanding the background of it variables along the manufacturing process, and using mechanical resistance as reference. The variables list is: the particle size of the coal, coal aging, percentage of coal in the mixture, adding binders, briquetting pressure and temperature of heat treatment. The results of this study indicate that these variables affect significantly the mechanical strength. Using Chipanga coal, the best compressive strength achieved was 19.82 MPa. It was considered the following manufacturing variables: the mixture ratio of 75:25 (wt% of iron ore and coal), fines of coal containing less than 0.075 mm, without binders, and heat treatment was performed at the temperature of coal´s maximum fluidity. Moreover, it was observed that the particles of iron ore were concentrated in the peripheral regions of the briquette after heat treatment, and that coal´s aging negatively affects the property of thermo-plasticity.

Este trabalho consiste no estudo da obtenção de aglomerados autorredutores na forma de briquetes a frio tratados termicamente, utilizando minério de ferro e carvão fóssil como matérias-primas. Esta promissora tecnologia tem como premissa a utilização da termo-plasticidade do carvão fóssil para conferir resistência e promover a auto-aglomeração. A obtenção de briquetes dá-se através de três etapas: condicionamento da mistura, briquetagem a frio e tratamento térmico. Os finos de carvão e minério são misturados e homogeneizados. A mistura, então, passa por processo de briquetagem a frio para compactação, promove o aumento de contato entre as partículas de carvão e minério. Finalmente tratamento térmico é realizado para obter a forma de um corpo sólido e coeso de auto-aglomerado autorredutor. O objetivo deste trabalho é determinar as melhores condições de obtenção de briquetes através do estudo de variáveis ao longo do processo de fabricação, utilizando a resistência mecânica como parâmetro. As variáveis estudadas são: granulometria do carvão, envelhecimento do carvão, percentual de carvão na mistura, adição de aglomerantes, pressão de compactação na briquetagem e temperatura de tratamento térmico. Os resultados obtidos neste estudo indicam que estas variáveis afetam significativamente a resistência mecânica. Utilizando-se o carvão Chipanga, o melhor resultado de resistência à compressão foi de 19,82 Mpa. Foram consideradas as seguintes condições de fabricação: mistura na proporção de 75:25 (% em massa) de minério para carvão Chipanga, o carvão continha finos inferiores à 0,075 mm, sem a adição de aglomerantes, e o tratamento térmico foi realizado na temperatura de máxima fluidez do carvão. Além disto, foi observado que as partículas de minério de ferro foram concentradas nas regiões periféricas do briquete após tratamento térmico, e que o envelhecimento do carvão afeta negativamente a propriedade de termo-plasticidade. / This work is focused in the study of obtaining self-reducing cold briquettes of agglomerates, by using iron ore and coal as raw materials. This promising technology has its foundation on the thermo plasticity of coal to manage high mechanical resistance when it is compared with self-reducing pellets. Three steps mainly describes how to obtaining briquettes: mixture, cold briquetting and heat treatment. Fines of raw material are mixed and cold briquetting process results in a compact mixture. This might lead to closer contact between particles of iron ore and coal. Finally, heat treatment is performed to achieve a cohesive body and solid shape containing self-reducing agglomerated. The main purpose of this job is to comprehend the fundamentals on how to obtain self-reducing cold briquettes of agglomerated carbon and iron, by understanding the background of it variables along the manufacturing process, and using mechanical resistance as reference. The variables list is: the particle size of the coal, coal aging, percentage of coal in the mixture, adding binders, briquetting pressure and temperature of heat treatment. The results of this study indicate that these variables affect significantly the mechanical strength. Using Chipanga coal, the best compressive strength achieved was 19.82 MPa. It was considered the following manufacturing variables: the mixture ratio of 75:25 (wt% of iron ore and coal), fines of coal containing less than 0.075 mm, without binders, and heat treatment was performed at the temperature of coal´s maximum fluidity. Moreover, it was observed that the particles of iron ore were concentrated in the peripheral regions of the briquette after heat treatment, and that coal´s aging negatively affects the property of thermo-plasticity.

A dissertação tem por cerne dois textos complementares, ambos refletindo o histórico de um programa de exploração mineral no distrito ferrífero de Curral Novo do Piauí. Como trabalho executado por empresa, a discussão sobre os custos e a definição de prioridades foram aspectos continuamente considerados. Assim os textos referidos refletem essas preocupações e se referem à proposição de métodos voltados à definição dos ambientes geológicos propícios à ocorrência de formações ferríferas à magnetita e à definição de probabilidade de ocorrências destes ambientes na fase de reconaissance da pesquisa. Na contextualização geológica do tema apresenta-se aspectos da geologia e uma discussão dos tipos e origens das formações ferríferas bandadas. Nos trabalhos foram aplicadas diversas técnicas, incluindo estatística multivariada, processamento digital de imagens, mapeamento geológico sistemático de superfície e subsuperfície em testemunhos de sondagens, caracterização petrográfica de rochas, geofísica de exploração a partir da utilização de métodos potenciais (magnetometria e radiometria). / This dissertation presents two complementary manuscripts, both reflecting the history of an exploration program in the Ferriferous Mineral District of Curral Novo do Piauí. As a research performed by a company, the discussion about the costs and prioritization aspects were continuously considered. The manuscripts reflects these concerns, referring to the proposition of methods aimed at defining the geological environments conducive to the occurrence of magnetite iron formations and the definition of probability of occurrence of these environments during the research reconnaissance phase. In the introductory chapter are presented the geological context and also a discussion of types and genesis of banded iron formations. In these studies were applied several techniques, including multivariate statistics, digital image processing, systematic geological surface mapping, diamond drill surveys, petrographic characterization of rocks and exploration geophysics methods (magnetometric and radiometric).

This master’s thesis evaluates five existing Convolutional Neural Network (CNN) models for semantic segmentation of optical microscopy images of iron ore pellets. The models are PSPNet, FC-DenseNet, DeepLabv3+, BiSeNet and GCN. The dataset used for training and evaluation contains 180 microscopy images of iron ore pellets collected from LKAB’s experimental blast furnace in Luleå, Sweden. This thesis also investigates the impact of the dataset size and data augmentation on performance. The best performing CNN model on the task was PSPNet, which had an average accuracy of 91.7% on the dataset. Simple data augmentation techniques, horizontal and vertical flipping, improved the models’ average accuracy performance with 3.4% on average. From the results in this thesis, it was concluded that there are benefits to using CNNs for analysis of iron ore pellets, with time-saving and improved analysis as the two notable areas.

A dissertação tem por cerne dois textos complementares, ambos refletindo o histórico de um programa de exploração mineral no distrito ferrífero de Curral Novo do Piauí. Como trabalho executado por empresa, a discussão sobre os custos e a definição de prioridades foram aspectos continuamente considerados. Assim os textos referidos refletem essas preocupações e se referem à proposição de métodos voltados à definição dos ambientes geológicos propícios à ocorrência de formações ferríferas à magnetita e à definição de probabilidade de ocorrências destes ambientes na fase de reconaissance da pesquisa. Na contextualização geológica do tema apresenta-se aspectos da geologia e uma discussão dos tipos e origens das formações ferríferas bandadas. Nos trabalhos foram aplicadas diversas técnicas, incluindo estatística multivariada, processamento digital de imagens, mapeamento geológico sistemático de superfície e subsuperfície em testemunhos de sondagens, caracterização petrográfica de rochas, geofísica de exploração a partir da utilização de métodos potenciais (magnetometria e radiometria). / This dissertation presents two complementary manuscripts, both reflecting the history of an exploration program in the Ferriferous Mineral District of Curral Novo do Piauí. As a research performed by a company, the discussion about the costs and prioritization aspects were continuously considered. The manuscripts reflects these concerns, referring to the proposition of methods aimed at defining the geological environments conducive to the occurrence of magnetite iron formations and the definition of probability of occurrence of these environments during the research reconnaissance phase. In the introductory chapter are presented the geological context and also a discussion of types and genesis of banded iron formations. In these studies were applied several techniques, including multivariate statistics, digital image processing, systematic geological surface mapping, diamond drill surveys, petrographic characterization of rocks and exploration geophysics methods (magnetometric and radiometric).

A análise de imagens automatizada tem atualmente importante papel no setor mineral, devido à rapidez das análises e à confiabilidade dos resultados. A técnica pode ser realizada por meio de imagens adquiridas em microscópio eletrônico de varredura, geralmente associada a microanálises químicas por EDS. Estas analises podem ser realizadas em diversas etapas de um empreendimento mineiro: no auxílio à exploração, lavra (blendagens), processos de beneficiamento (associação mineral), estudos de gênese e controles de mineralização. Essa técnica permite a análise estatística de grande número de partículas/dados, fornecendo informações de composição mineralógica, química mineral, partição de elementos, associações minerais incluindo liberação de fases de interesse, entre outros. Este estudo investiga a aplicabilidade da análise de imagens automatizada em amostras de minério de ferro, com base em diferentes procedimentos de preparação de amostras e rotinas de análise avaliadas por meio do sistema MLA. Um minério de ferro foi escolhido por se tratar de um minério já bastante estudado e bem documentado na bibliografia e que mostra, em geral, mineralogia e texturas simples e repetitivas facilitando a análise dos resultados obtidos com os diferentes procedimentos e rotinas aplicadas. Além disso, o minério de ferro apresenta fases minerais com significativas diferenças de peso específico, o que pode acarretar em maiores dificuldades em termos de amostragem e preparação de amostras. / The automated image analysis has an important role in the mineral industry due to the quickly analysis and the results reliability. The technique can be applied using images from a scanning electron microscope associated usually coupled with chemical microanalysis from an EDS system. These analyses are carried out in many stages of a mining project helping mineral exploration, mining (blending), mineral processing (mineral association), genetic studies and mineralization control. This technique allows a statistic analysis of a large numbers particles and data, providing information of mineralogical composition, mineral chemistry, elemental distribution, mineral associations, phase and spectra liberation and others. This study sets the applicability of automated image analysis of an iron ore sample with diverse preparation procedures and analysis routines, which were evaluated by the MLA system. An iron ore sample was chosen because it is a familiar and well-documented ore in the literature, that usually shows simple textures and mineralogy which makes easier the interpretation of results by a diversity of preparation procedures and analysis routines. Furthermore, the iron ore shows mineral phases with significant differences in specific gravity resulting in more difficulties in sampling and preparation procedures due to potential density segregation.