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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

[en] STUDY OF THE PROCESSING OF SULPHIDE ORES OF GOLD WITH THE LOWEST GRADE OF GOLD / [pt] ESTUDO DO BENEFICIAMENTO DE UM MINÉRIO SULFETADO DE OURO DE BAIXO TEOR

SARA VIRGINIA CHUMPITAZ BRAVO 29 September 2003 (has links)
[pt] No presente trabalho são avaliados os fatores físicos e químicos que influenciam o processamento do minério sulfetado de mais baixo teor de ouro conhecido no mundo. A amostra de minério estudada é proveniente da Rio Paracatu Mineração S.A - RPM e é identificada como minério Calha Brava Cl-4, pertencente ao Banco 716, Bloco 508-B da mina. Alguns circuitos de beneficiamento de minérios auríferos incluem processos de concentração gravítica e flotação visando atingir máximas recuperações de ouro e, conseqüentemente, elevada produção a baixo custo. A seleção das técnicas de processamento do minério depende, basicamente, da mineralogia e distribuição das partículas minerais no minério, do tamanho da partícula de ouro ou dos minerais e outros metais associados ao minério. A distribuição do teor de ouro nas diferentes frações granulométricas do minério Calha Brava Cl-4 revelam que 80,4 por cento do ouro encontra-se na fração acima de 104 um e 25 por cento encontram-se na fração fina (< 28 um). A recuperação total de ouro, enxofre e arsênio obtida nos ensaios de concentração gravítica por meio do concentrador centrífugo Knelson e flotação foram 80,44 por cento, 64,9 por cento e 58,22 por cento, respectivamente. A recuperação em massa dessa etapa foi 10,14 por cento. A recuperação total de ouro, enxofre e arsênio obtidos na concentração de jigagem e flotação foi 88,91 por cento, 86,82 por cento e 49,07 por cento, respectivamente. A recuperação em massa do concentrado recuperado foi de 19,5 por cento. Nos ensaios de flotação direta, a maior recuperação de ouro (87 por cento) foi obtida para o minério cominuído a uma granulometria com P80 = 86 um e recuperado por flotação na presença de 30 g/t do coletor amil xantato de potássio (AXP), 20 g/t de metil isobutil carbinol (MIBC), pH 6,3 e potencial de polpa 0,209 V vs Eh, em relação ao eletrodo de hidrogênio. A recuperação em massa do concentrado obtida foi 4 por cento. No caso das partículas grossas do minério (P80 = 130 um), constatou-se a necessidade de maiores concentrações do coletor. A maior recuperação de ouro (85,33 por cento) foi obtida com a concentração de 60 g/t para o AXP, pH 6,3 e potencial de polpa de 0,218 V vs Eh. A recuperação em massa do concentrado foi de 9 por cento. / [en] The work involves the evaluation of physical and chemical factors that influence the processing of sulphide ores, with the lowest grade of gold known in the world. The studied sample is from Rio Paracatu Mining S.A. and is described as Calha Brava Cl-4, belonging to the 716 bench, block 508-B in the mine. Some industrial processing of gold include gravity concentration and flotation processes in order to reach the maximum gold recovery, aiming at raising production levels with lower costs. The selection of the mineral processing depends on several factors as mineralogy, particle size distribution and other minerals associated with the ore. The distribution of gold grades to the different size fractions in the studied ore, reveals that 80.48 percent of gold occur in the particle size fraction above 104 um, and 25 percent of gold occur in the fine fraction (< 28 um). The global gold, sulphur and arsenic recoveries, obtained by centrifuge gravity concentration (Knelson)and flotation tests, were 80.44 percent, 64.90 percent and 58.22 percent, respectively. To these processes, the mass recovery was 10.14 percent. The total gold, sulphur and arsenic recoveries obtained in concentration processes by jig and flotation techniques were 88.91 percent, 86.82 percent and 49.07 percent, respectively. The mass recovery was 19.5 percent. In the flotation tests, the maximum gold recovery (87 percent) was obtained with the grounded ore (P80 = 86 um), using 30 g/t collector potassium amyl xanthate (PAX), 20 g/t methyl isobuthyl carbinol (MIBC), pH = 6.3 and potential of pulp 0.209 V vs Eh. The mass recovery was approximately 4 percent. When coarse particles (P80 = 130 um) were floated, the need of am increase in the collector concentration was observed. The maximum ore recovery (85.33 percent) was obtained at concentration of 60 g/t PAX, pH = 6.3 and potential of pulp 0.218 V vs Eh. The mass recovery was 9 percent.
322

Microscopia multimodal prática: registro automático de imagens de microscopia ótica e de microscopia eletrônica de varredura / Multimodal microscopy practice: automatic image registration for optical microscopy and scanning electron microscopy

Marcos Paulo Galdino de Lima 07 May 2014 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A discriminação de fases que são praticamente indistinguíveis ao microscópio ótico de luz refletida ou ao microscópio eletrônico de varredura (MEV) é um dos problemas clássicos da microscopia de minérios. Com o objetivo de resolver este problema vem sendo recentemente empregada a técnica de microscopia colocalizada, que consiste na junção de duas modalidades de microscopia, microscopia ótica e microscopia eletrônica de varredura. O objetivo da técnica é fornecer uma imagem de microscopia multimodal, tornando possível a identificação, em amostras de minerais, de fases que não seriam distinguíveis com o uso de uma única modalidade, superando assim as limitações individuais dos dois sistemas. O método de registro até então disponível na literatura para a fusão das imagens de microscopia ótica e de microscopia eletrônica de varredura é um procedimento trabalhoso e extremamente dependente da interação do operador, uma vez que envolve a calibração do sistema com uma malha padrão a cada rotina de aquisição de imagens. Por esse motivo a técnica existente não é prática. Este trabalho propõe uma metodologia para automatizar o processo de registro de imagens de microscopia ótica e de microscopia eletrônica de varredura de maneira a aperfeiçoar e simplificar o uso da técnica de microscopia colocalizada. O método proposto pode ser subdividido em dois procedimentos: obtenção da transformação e registro das imagens com uso desta transformação. A obtenção da transformação envolve, primeiramente, o pré-processamento dos pares de forma a executar um registro grosseiro entre as imagens de cada par. Em seguida, são obtidos pontos homólogos, nas imagens óticas e de MEV. Para tal, foram utilizados dois métodos, o primeiro desenvolvido com base no algoritmo SIFT e o segundo definido a partir da varredura pelo máximo valor do coeficiente de correlação. Na etapa seguinte é calculada a transformação. Foram empregadas duas abordagens distintas: a média ponderada local (LWM) e os mínimos quadrados ponderados com polinômios ortogonais (MQPPO). O LWM recebe como entradas os chamados pseudo-homólogos, pontos que são forçadamente distribuídos de forma regular na imagem de referência, e que revelam, na imagem a ser registrada, os deslocamentos locais relativos entre as imagens. Tais pseudo-homólogos podem ser obtidos tanto pelo SIFT como pelo método do coeficiente de correlação. Por outro lado, o MQPPO recebe um conjunto de pontos com a distribuição natural. A análise dos registro de imagens obtidos empregou como métrica o valor da correlação entre as imagens obtidas. Observou-se que com o uso das variantes propostas SIFT-LWM e SIFT-Correlação foram obtidos resultados ligeiramente superiores aos do método com a malha padrão e LWM. Assim, a proposta, além de reduzir drasticamente a intervenção do operador, ainda possibilitou resultados mais precisos. Por outro lado, o método baseado na transformação fornecida pelos mínimos quadrados ponderados com polinômios ortogonais mostrou resultados inferiores aos produzidos pelo método que faz uso da malha padrão. / The discrimination of phases that are practically undistinguishable to the optical microscope of reflected light or to the scanning electron microscope (SEM) is one of the classical problems in ore microscopy. With the aim of solving this problem it has been recently used the technique of co-located microscopy that consists in the junction of two microscopy modalities, optical microscopy and scanning electron microscope. The aim of the technique is to provide an image of the multimodal microscopy, becoming possible the identification, in mineral samples, of phases that wouldnt be distinguished by the use of one modality only, overcoming the individual limitations of the two systems. The method of register available so far in literature to the fusion of optical microscopy and scanning electron microscope images is a hard-working procedure and extremely dependent on the operator interaction, once it involves the system calibration with a standard mesh in each routine of images acquisition. Due to this reason the current technique is not practical. This piece of work proposes a methodology in order to automate the process of images register in optical microscopy and scanning electron microscopy in a way to improve and simplify the co-located microscopy technique. The proposed method may be divided in two procedures: acquisition of transformation and register of the images with the use of this transformation. The acquisition of transformation involves, first, the pre-processing of pairs in a way of performing a crude register among the images of each pair. Then, homologous points are achieved in the optical and in SEM images. In order to this, it has been used two methods, the first one was developed based in algorithm SIFT and the second was defined from the sweeping of the highest of coefficient correlation. In the following step it is calculated the transformation. Two different approaches were used: the local weighted mean (LWM) and the weighted least squares with orthogonal polynomials (MQPPO). The LWM receives as entrance what we call pseudo-counterparts, points that are distributed in a regular way in the reference image, and that reveal, in the image to be registered, the relative local dislocation among the images. Those pseudo-counterparts may be obtained by SIFT or by the method of correlation coefficient. On the other side, the MQPPO receives a group of points with natural distribution. The analysis of the images registration obtained employed as a metric the value of correlation among the obtained images. It was noticed that with the use of the proposed variants SIFT-LWM and SIF-Correlation were obtained slightly higher results than the ones from the method with standard mesh and LWM. Thus, the proposal, besides reducing drastically the operator intervention, still enabled more exact results. On the other side, the method based in the transformation provided by the minimum square pondered with orthogonal polynomial showed lower results than to the ones produced by the method that used standard mesh
323

Résultants de polynômes de Ore et Cryptosystèmes de McEliece sur des Codes Rang faiblement structurés / Resultants of Ore polynomials and McEliece Cryptosystems based on weakly structured Rank Codes

Murat, Gaetan 09 December 2014 (has links)
Les techniques de chiffrement les plus utilisées en cryptographie, basées sur des problèmes de théorie des nombres, présentent malgré leur efficacité des défauts notamment une vulnérabilité aux attaques menées à l'aide d'ordinateur quantiques. Il est donc pertinent d'étudier d'autres familles de cryptosystèmes. Nous nous intéressons ici aux cryptosystèmes basés sur les codes correcteurs, introduits par McEliece en 1978 qui, étant basés sur des problèmes difficiles de théorie des codes, ne présentent pas cette vulnérabilité. Ces cryptosystèmes présentent des inconvénients, qui font qu'ils sont peu utilisés en pratique. Selon le code choisi, ils peuvent être vulnérables aux attaques structurelles, mais surtout ils nécessitent des clés de taille très importante.Récemment une nouvelle famille de codes appelés codes MDPC a été introduite ainsi qu'un cryptosystème basé sur cette famille de codes. Les codes MDPC semblent être distinguables seulement en trouvant des mots de poids faibles dans leur dual, les affranchissant ainsi d'une éventuelle vulnérabilité aux attaques structurelles. De plus, en utilisant une des matrices quasi-cycliques, ils obtiennent des clés de taille très compacte.Nous avons pour notre part, travaillé dans le contexte de la métrique rang, une nouvelle métrique introduite en 1985 par Gabidulin qui semble bien adaptée à une utilisation en cryptographie :• Nous avons commencé par travailler autour de la notion de polynôme de Ore et le cas particulier important des q-polynômes. Ces derniers sont des combinaisons linéaires des itérés de l'automorphisme de Frobenius sur un corps fini.Ces polynômes constituent un objet d'étude important en métrique rang, de par leur utilisation dans les premiers cryptosystèmes dans cette métrique. Nous présentons sous une nouvelle forme des résultats déjà connus, et de nouveaux algorithmes pour le calcul du PGCD de deux polynômes de Ore et le calcul des résultants et sous-résultants de polynômes de Ore (ainsi que de polynômes usuels en généralisant au calcul des sous-résultants la formule déjà connue pour les résultants) en utilisant une matrice de multiplication à droite plus petite que la matrice de Sylvester utilisée habituellement.Ces résultats peuvent être réexploités indirectement dans le cryptosystème présenté par la suite bien que celui-ci ne soit pas basé sur les q-polynômes.• La partie suivante de notre travail est consacrée à l'introduction d'une nouvelle famille de codes en métrique rang appelés codes LRPC (pour Low Rank Parity Check codes). Ces codes ont la particularité d'avoir une matrice de parité de poids rang faible (et peuvent donc être vus comme une généralisation des codes LDPC ou MDPC à la métrique rang).Nous présentons le cryptosystème LRPC, un cryptosystème de type Mc Eliece en métrique rang basé sur les codes LRPC. Ces codes sont très peu structurés et sont donc vraisemblablement résistants aux attaques structurelles. La matrice de parité peut être choisie doublement circulante (on parle alors de codes DC-LRPC) ce qui diminue considérablement la taille de la clé.Ainsi, le cryptosystème DC-LRPC cumule les avantages d'offrir une bonne sécurité en étant basé sur un problème difficile (comme tous les cryptosystèmes basés sur les codes correcteurs), d'être faiblement structurés, de disposer d'une clé de taille assez petite (quelques milliers de bits au plus) et d'un algorithme de décodage efficace.Une attaque a été trouvée dans le cas du cryptosystème DC-LRPC. Cette attaque basée sur la notion de code replié permet de baisser significativement la sécurité du cryptosystème dans le cas où le polynôme X^(k-1)+X^(k-2)+⋯+1 est scindable (k désignant la dimension du code). Cependant ce n'est pas le cas pour les paramètres présentés où le cryptosystème reste valide. / The most commonly used encryption techniques in cryptography are based on problems in number theory. Despite their efficiency, they are vulnerable to post-quantum cryptographic attack. Therefore it is relevant to study other types of cryptosystems. In this work we study error-corrector codes based cryptosystmems, introduced by McEliece in 1978 ; being based on hard problems in coding theory, these cryptosystems do not have this weakness. However these cryptosystems are almost not used in practice because they are vulnerable to strucural attacks and they require a key with very big length. Recently a new family of codes named MDPC codes has been introduced as well as a cryptosystem that is based on these codes. It seems that MDPC codes are distinguishable only by finding words with weak weight in their dual, thus preventing them from structural attacks. Furthermore, they can have compact keys by using quasi-cyclic matrices.In the present paper we use the rank metric, a new metric for codes that was introduced by Gabidulin in and seems suited for a cryptographic use :• At first we studied Ore Polynomials and the special case of q-polynomials , the latter being iterates of the Fobenius automorphism on a finite field.These polynomials are widely in rank metric due to their use in the first code-based cryptosystems in rank metric. We reformulate already known results and give new results regarding the computation of GCD, resultants and subresultants of two Ore polynomials (as well as usual polynomials for which we give a generalization of the resultant computation to subresultants) using a right-hand multiplication matrix which is smaller than the well-known Sylvester matrix.These results may be reused in the cryptosystem we introduce in the next chapters, though this cryptosystem is not based on q-polynomials.• In the next part of our work we define the LRPC codes (for Low Rank Parity Check Codes), a new family of codes in rank metric. These codes have a parity check matrix whose rank weight is low (and thus they can be seen as a generalization of LDPC or MDPC codes to rank metric).We present the LRPC cryptosystem, a McEliece cryptosystem in rank metric based on LRPC codes. These codes are weakly structured and so are likely to resist structural attacks. We can choose a double-circulant parity check matrix which greatly lowers the key size (we name these particular codes DC-LRPC codes).Thus the DC-LRPC cryptosystems have a good security (being based on a hard problem in coding theory), are weakly structured, have small public keys and can be quickly decoded.An attack was found for DC-LRPC cryptosystem. This attack relies on folded codes and may greatly lower the security of the cryptosystem, however it works only when the polynomial X^(k-1)+X^(k-2)+⋯+1 has a divisor with big degree. We give parameters for which the cryptosystem remains valid.
324

Semantic Segmentation of Iron Pellets as a Cloud Service

Christopher, Rosenvall January 2020 (has links)
This master’s thesis evaluates automatic data annotation and machine learning predictions of iron ore pellets using tools provided by Amazon Web Services (AWS) in the cloud. The main tool in focus is Amazon SageMaker which is capable of automatic data annotation as well as building, training and deploying machine learning models quickly. Three different models was trained using SageMakers built in semantic segmentation algorithm, PSP, FCN and DeepLabV3. The dataset used for training and evaluation contains 180 images of iron ore pellets collected from LKAB’s experimental blast furnace in Luleå, Sweden. The Amazon Web Services solution for automatic annotation was shown to be of no use when annotating microscopic images of iron ore pellets. Ilastik which is an interactive learning and segmentation toolkit showed far superiority for the task at hand. Out of the three trained networks Fully-Convolutional Network (FCN) performed best looking at inference and training times, it was the quickest network to train and performed within 1% worse than the fastest in regard to inference time. The Fully-Convolutional Network had an average accuracy of 85.8% on the dataset, where both PSP &amp; DeepLabV3 was showing similar performance. From the results in this thesis it was concluded that there are benefits of running deep neural networks as a cloud service for analysis and management ofiron ore pellets.
325

Kupfer im Erzgebirge: Kupfererz - Vorkommen und Abbau im Erzgebirge zwischen 1470 und 1750

Bittmann, Hartmut Carsten January 2014 (has links)
Über Jahrhunderte ist das Erzgebirge durch Montanindustrie geprägt worden. Zahlreiche Publikationen beschreiben lagerstättenkundliche und bergbaugeschichtliche Verhältnisse. Besondere Beachtung fanden dabei die Erze des Silbers und Zinns. Eine umfassende Übersicht zu Vorkommen und Abbau von Kupfer liegt jedoch noch nicht vor. Anliegen der vorliegenden Untersuchung war es deshalb, eine Zusammenschau der erzgebirgischen Kupfervorkommen zu erarbeiten. Dabei stand im Blickpunkt, in welchen Lagerstättentypen Kupfer mineralisierte und in welchen Revieren Kupfer nachweisbar ist. Dieser Überblick konnte durch Vergleichen von lagerstättenkundlicher Literatur und Kartenmaterial erreicht werden. Des Weiteren sollten Abbaureviere und Abbaumengen von Kupfer im Zeitraum von 1470 bis 1750 unter Zuhilfenahme von Material aus dem Bergarchiv Freiberg und einzelner Hinweise in weiterer, den erzgebirgischen Bergbau betreffender Literatur ausgemacht werden. Die Recherchen haben gezeigt, dass Kupferminerale, fast ausschließlich sulfidisch mineralisiert, in allen Lagerstättentypen anzutreffen sind. Bezüglich der räumlichen Verteilung sind verschiedene Schwerpunkte erkennbar. Für den Bergbau spielte Kupfer trotz des engen verhüttungstechnischen Zusammenhangs mit Silbererzen in vielen Bergbaurevieren eine nur untergeordnete Rolle. Größere Mengen des Buntmetalls wurden in Schneeberg-Oberschlema, in Breitenbrunn, bei Annaberg, bei Marienberg, bei Freiberg und in Sadisdorf gefördert. Über Vorkommen und historischen Abbau von Kupfererzen gibt die Arbeit einen Überblick, der den sächsischen und böhmischen Teil des Erzgebirges umfasst. Damit ist eine Grundlage für weiterführende Untersuchungen zur Bedeutung von Kupfer in der sächsischen Montangeschichte geschaffen.:Abkürzungsverzeichnis..........3 Abbildungsverzeichnis..........3 Tabellenverzeichnis..........4 1. Einleitung..........6 2. Untersuchungsgebiet..........9 2.1 Räumliche Abgrenzung..........9 2.2 Geologischer Bau und Entwicklungsgeschichte..........13 2.3 Physisch-geographischer Überblick..........17 2.3.1 Boden..........17 2.3.2 Relief..........18 2.3.3 Klima und Vegetation..........19 3. Material und Methodik..........20 3.1 Teilgebiete innerhalb des Untersuchungsraumes..........20 3.2 Untersuchungen zu den Kupferlagerstätten im Erzgebirge..........22 3.3 Untersuchungen zum Kupfererzabbau 1470 bis 1750..........25 3.4 Begriffe, Einheiten und Namen..........26 4. Lagerstätten im Erzgebirge..........27 4.1 Überblick..........27 4.2 Prävariszische Erzlagerstätten..........29 4.2.1 Einordnung..........29 4.2.2 Konkordante Erzlager..........30 4.2.3 Prävariszische Skarne..........31 4.2.4 Felsitmineralisation..........31 4.3 Variszische Erzlagerstätten..........32 4.3.1 Einordnung..........32 4.3.2 Greisen und Zwitter..........32 4.3.3 Variszische Skarne..........33 4.4 Postvariszische Erzlagerstätten..........33 5. Vorkommen von Kupferlagerstätten im Erzgebirge..........35 5.1 Teilgebiet Schneeberg-Schwarzenberg..........35 5.1.1 Störungssysteme und hydrothermale Gänge..........35 5.1.2 Kupfermineralisationen in den Folgengruppen..........37 5.1.3 Einzelne Kupfervorkommen im Teilgebiet..........38 5.2 Teilgebiet Marienberg-Annaberg..........43 5.2.1 Störungssysteme und hydrothermale Gänge..........43 5.2.2 Kupfermineralisationen in den Folgengruppen..........46 5.2.3 Einzelne Kupfervorkommen im Teilgebiet..........47 5.3 Teilgebiet Freiberg..........50 5.3.1 Störungssysteme und hydrothermale Gänge..........50 5.3.2 Kupfermineralisation in den Folgengruppen..........52 5.3.3 Einzelne Kupfervorkommen im Teilgebiet..........55 5.4 Teilgebiet Altenberg-Glashütte..........56 5.4.1 Ausrichtung und Mineralisation der hydrothermalen Gänge..........56 5.4.2 Einzelne Kupfervorkommen im Teilgebiet..........59 6. Kupfererzabbau von 1470 bis 1750..........61 6.1 Teilgebiet Schneeberg-Schwarzenberg..........61 6.1.1 Kupferförderung im gesamten Teilgebiet..........61 6.1.2 Einzelne Abbaugebiete im Teilgebiet..........61 6.2 Teilgebiet Marienberg-Annaberg..........67 6.2.1 Kupferförderung im gesamten Teilgebiet..........67 6.2.2 Einzelne Abbaugebiete im Teilgebiet..........68 6.3 Teilgebiet Freiberg..........74 6.3.1 Kupferförderung im gesamten Teilgebiet..........74 6.3.2 Einzelne Abbaugebiete im Teilgebiet..........74 6.4 Teilgebiet Altenberg-Glashütte..........77 6.4.1 Kupferförderung im gesamten Teilgebiet..........77 6.4.2 Einzelne Abbaugebiete im Teilgebiet..........77 7. Überblick Teilgebiet Böhmisches Erzgebirge..........80 8. Ergebnisse..........81 9. Ausblick..........86 10. Zusammenfassung..........87 Liste bergmännischer Begriffe und Maße..........91 Liste der Minerale..........92 Literaturverzeichnis..........93 / The mountains Erzgebirge have been characterized by mining industries for centuries. Many publications describe the natural mineral deposits and the historical mining conditions. Special regards are thereby paid to silver and tin ore. However an extensive summary of copper deposits and mining is not available. In which types of mineral deposits copper is mineralised and in which districts copper can be proved? Therefore, the intention of this study was a synopsis about the copper deposits in the mountains Erzgebirge by comparing literature and maps. In addition, mining districts and mining quantity of copper between 1470 and 1750 should be arranged. For this purpose, material from the Bergarchiv Freiberg and other literature about regional mining was used. The research showed that copper minerals, nearly exclusive sulphide-mineralised, can be proved in every type of mineral deposits. In terms of the zonal distribution, there are centres visible. In spite of the closely relation to silver ore in the smelting processes copper was not very important in many mining districts. A larger quantity of copper ore was won in Schneeberg-Oberschlema, in Breitenbrunn, near Annaberg, near Marienberg, near Freiberg and in Sadisdorf. The study shows an overview of deposits and historical mining of copper ore in the Saxon and Bohemian parts of the Erzgebirge. So the work can be a basis for continuative studies about the importance of copper for the Saxon mining history.:Abkürzungsverzeichnis..........3 Abbildungsverzeichnis..........3 Tabellenverzeichnis..........4 1. Einleitung..........6 2. Untersuchungsgebiet..........9 2.1 Räumliche Abgrenzung..........9 2.2 Geologischer Bau und Entwicklungsgeschichte..........13 2.3 Physisch-geographischer Überblick..........17 2.3.1 Boden..........17 2.3.2 Relief..........18 2.3.3 Klima und Vegetation..........19 3. Material und Methodik..........20 3.1 Teilgebiete innerhalb des Untersuchungsraumes..........20 3.2 Untersuchungen zu den Kupferlagerstätten im Erzgebirge..........22 3.3 Untersuchungen zum Kupfererzabbau 1470 bis 1750..........25 3.4 Begriffe, Einheiten und Namen..........26 4. Lagerstätten im Erzgebirge..........27 4.1 Überblick..........27 4.2 Prävariszische Erzlagerstätten..........29 4.2.1 Einordnung..........29 4.2.2 Konkordante Erzlager..........30 4.2.3 Prävariszische Skarne..........31 4.2.4 Felsitmineralisation..........31 4.3 Variszische Erzlagerstätten..........32 4.3.1 Einordnung..........32 4.3.2 Greisen und Zwitter..........32 4.3.3 Variszische Skarne..........33 4.4 Postvariszische Erzlagerstätten..........33 5. Vorkommen von Kupferlagerstätten im Erzgebirge..........35 5.1 Teilgebiet Schneeberg-Schwarzenberg..........35 5.1.1 Störungssysteme und hydrothermale Gänge..........35 5.1.2 Kupfermineralisationen in den Folgengruppen..........37 5.1.3 Einzelne Kupfervorkommen im Teilgebiet..........38 5.2 Teilgebiet Marienberg-Annaberg..........43 5.2.1 Störungssysteme und hydrothermale Gänge..........43 5.2.2 Kupfermineralisationen in den Folgengruppen..........46 5.2.3 Einzelne Kupfervorkommen im Teilgebiet..........47 5.3 Teilgebiet Freiberg..........50 5.3.1 Störungssysteme und hydrothermale Gänge..........50 5.3.2 Kupfermineralisation in den Folgengruppen..........52 5.3.3 Einzelne Kupfervorkommen im Teilgebiet..........55 5.4 Teilgebiet Altenberg-Glashütte..........56 5.4.1 Ausrichtung und Mineralisation der hydrothermalen Gänge..........56 5.4.2 Einzelne Kupfervorkommen im Teilgebiet..........59 6. Kupfererzabbau von 1470 bis 1750..........61 6.1 Teilgebiet Schneeberg-Schwarzenberg..........61 6.1.1 Kupferförderung im gesamten Teilgebiet..........61 6.1.2 Einzelne Abbaugebiete im Teilgebiet..........61 6.2 Teilgebiet Marienberg-Annaberg..........67 6.2.1 Kupferförderung im gesamten Teilgebiet..........67 6.2.2 Einzelne Abbaugebiete im Teilgebiet..........68 6.3 Teilgebiet Freiberg..........74 6.3.1 Kupferförderung im gesamten Teilgebiet..........74 6.3.2 Einzelne Abbaugebiete im Teilgebiet..........74 6.4 Teilgebiet Altenberg-Glashütte..........77 6.4.1 Kupferförderung im gesamten Teilgebiet..........77 6.4.2 Einzelne Abbaugebiete im Teilgebiet..........77 7. Überblick Teilgebiet Böhmisches Erzgebirge..........80 8. Ergebnisse..........81 9. Ausblick..........86 10. Zusammenfassung..........87 Liste bergmännischer Begriffe und Maße..........91 Liste der Minerale..........92 Literaturverzeichnis..........93
326

A modelling framework to determine the value proposition of microwave treatment of mineral ores

Charikinya, Edson 03 1900 (has links)
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The extraction of mineral values from ore requires liberation of the minerals followed by separation. Liberation is achieved by size reduction operations which are inefficient processes typically accounting for up to 70% of the energy consumption in a mineral concentrator (Tromans, 2008). As the grade of ores reserves declines, future viability of mineral operations will be determined by the costs of comminution. Recent work has shown that microwave treatment of secondary crusher product at specific microwave energy consumption of the order of 1 kWh/t reduces the work index of the ore and increases grade and recovery in batch flotation tests. Improved liberation at coarse sizes was also demonstrated (Kingman, 2006). Based on these findings work is ongoing to commercialise the technology. The objective of this study is to develop a modelling framework to determine the value proposition of microwave treatment of ore. It was noted that various models exist in literature for modelling of mineral processing flotation flow sheets, but these models do not incorporate the feed ore liberation property as an input variable in their calculations. Thus, a fundamentally derived property based model was identified as appropriate for flow sheet modelling of microwave treated ore, as it utilised liberation as an indirect variable in calculating the flotation rate constant through the use of contact angle to describe particle surface hydrophobicity. The model was successfully incorporated into the flotation flow sheet units developed in HSC Chemistry and used with Mineral Liberation Analyser (MLA) data to investigate the effects of changes in feed ore liberation on rougher cell flotation recovery. Different liberation scenarios based around modification of porphyry copper flotation feed were created. A sensitivity analysis of the various feed stream liberation scenarios was carried out to test the ability of the model to effectively model the differences in downstream processing of microwave treated and untreated ores. For a single flotation cell of size 85 m3 with a solids feed flow rate of 890 tph, it was observed that below a certain size (120 μm in the case of the porphyry copper ore) changes in flotation feed liberation had no significant effect on value mineral recovery. Significant differences in value mineral recovery were observed only at coarser sizes above 120 μm. The results indicated that improvement in recovery of value minerals due to improved liberation from applying microwave technology has size limits and is significantly dependent on the feed grind size. Feed grind size sensitivity analysis was then carried on the same single cell flow sheet utilising feeds with the same mineralogy but with different grind sizes. The results indicated that maximum benefits from the application of microwave technology would be best obtained by utilising coarse grinding at sizes between P70 = 200 μm and P70 = 300 μm for the porphyry copper ores considered in this study. Coarse grinding appears to be the best way to exploit improved liberation in downstream processing of microwave treated ores. Investigations similar to those carried out on the single cell flotation flow sheet were then carried out on a continuous plant rougher flotation flow sheet. The flow sheet consisted of nine rougher cells in series each with a volume of 85 m3 with a solids feed flow rate of 890 tph into the bank of rougher cells. The results indicated that there was no significant difference in final rougher bank overall cumulative recovery at fine grind sizes below a P70 grind size of 120 μm with improvements in feed ore liberation. Feed grind size sensitivity analysis showed a significant variation in cumulative recovery at coarse grind sizes of above P70 = 129 μm .This variation was attributed to improvements in flotation feed ore value mineral liberation from locked composite particles to the maximum possible theoretical liberation scenario of fully liberated value mineral particles. A 7.2 percentage point improvement in cumulative value mineral overall recovery and a 2 to 3 percentage point improvement in enrichment ratio was also observed above the P70 = 250 μm grind sizes after improving the flotation feed ore value mineral particle liberation of a typical flotation plant feed to a maximum. The increases in grade and cumulative recovery at coarse sizes were attributed to improvements to the flotation plant feed ore value mineral particle liberation. From the results, it was concluded that microwave technology application will offer greater benefits in downstream processing of coarse ground ores. / AFRIKAANSE OPSOMMING: Die ekstraksie van mineraalwaardes uit erts vereis bevryding van die minerale gevolg deur skeiding. Bevryding word bereik deur verkleiningsprosedures wat ondoeltreffende prosesse is en wat gewoonlik vir tot 70% van die energieverbruik in ʼn mineraalkonsentreerder verantwoordelik is (Tromans, 2008). Algaande die graad van ertsreserwes afneem, sal toekomstige lewensvatbaarheid van mineraalprosesse bepaal word deur die koste van vergruising. Onlangse werk het getoon dat mikrogolfbehandeling van sekondêre vergruiserproduk by spesifieke mikrogolf-energieverbruik van ongeveer 1 kWh/t die werkindeks van die erts verminder en die graad en opbrengs in lotflottasietoetse verhoog. Verbeterde bevryding by growwer groottes is ook aangetoon (Kingman, 2006). Werk gaan voort op grond van hierdie bevindinge ten einde die tegnologie te kommersialiseer. Die doel van hierdie navorsing is om ʼn modelleringsraamwerk te ontwikkel om die waardeproposisie van mikrogolfbehandeling van erts te bepaal. Daar is in die literatuur afgekom op verskeie modelle vir die modellering van vloeidiagramme vir flottasie van mineraalverwerking, maar hierdie modelle inkorporeer nie die voerertsbevrydingseienskap as ʼn insetveranderlike in hulle berekeninge nie. ʼn Fundamentele afgeleide eienskapgebaseerde model is geïdentifiseer as geskik vir vloeidiagrammodellering van mikrogolfbehandelde erts, aangesien dit bevryding as ʼn indirekte veranderlike by die berekening van die flotteertempokonstante aangewend het deur die gebruik van kontakhoek om hidrofobisiteit van die deeltjieoppervlak te beskryf. Die model is suksesvol in eenhede van die flottasievloeidiagram wat in HSC Chemistry ontwikkel is, geïnkorporeer en tesame met data van die mineraalbevrydingsontleder (MBO) gebruik om die gevolge van veranderinge in voerertsbevryding op die opbrengs van voorskeiselflottasie te ondersoek. Verskillende bevrydingscenario’s is geskep wat óm die modifisering van porfierkoperflotteringstoevoer heen gebaseer is. ʼn Sensitiwiteitsontleding van die verskillende voerstroombevrydingscenario’s is uitgevoer om die vermoë van die model om die verskille in stroomaf-verwerking van mikrogolfbehandelde en onbehandelde ertse te toets, doeltreffend te modelleer. In die geval van ʼn enkele flottasiesel van 85 m3 groot met ʼn vastestof-toevoervloeitempo van 890 tph, is waargeneem dat veranderinge in flottasietoevoer-bevryding benede ʼn sekere grootte (120 μm in die geval van die porfierkopererts) geen beduidende uitwerking op die opbrengs van die waardemineraal gehad het nie. Beduidende verskille in die opbrengs van die waardemineraal is slegs by growwer groottes bo 120 μm waargeneem. Die resultate het daarop gedui dat verbetering in die opbrengs van waardeminerale as gevolg van verbeterde bevryding ná die toepassing van mikrogolftegnologie beperkinge ten opsigte van grootte het en opvallend afhanklik is van die toevoermaalgrootte. Sensitiwiteitstoetsing van toevoermaalgrootte is daarna op dieselfde enkele selvloeidiagram wat voerders met dieselfde mineralogie gebruik uitgevoer, maar met verskillende maalgroottes. Die resultate het daarop gedui dat maksimum voordele van die toepassing van mikrogolftegnologie die beste verkry sou word deur gebruik van growwe maling by groottes tussen P70 = 200 μm en P70 = 300 μm vir die porfierkoperertse wat in hierdie navorsing in oorweging geneem is. Growwe maling skyn die beste manier te wees om verbeterde bevryding in stroomaf-verwerking van mikrogolfbehandelde ertse te eksploiteer. Ondersoeke soortgelyk aan dié wat op die vloeidiagram van die enkelselflottasie uitgevoer is, is toe op ʼn deurlopende vloeidiagram van die aanlegvoorskeierflottasie uitgevoer. Die vloeidiagram het bestaan uit nege voorskeiselle in serie elk met ʼn volume van 85 m3 met ʼn vastestof-toevoervloeitempo van 890 tph in die ry voorskeiselle. Die resultate het daarop gedui dat daar geen aanmerklike verskil in algemene kumulatiewe opbrengs van die finale voorskeiry by fyn maalgroottes benede ʼn P70-maalgrootte van 120 μm met verbeteringe in voerertsbevryding was nie. Sensitiwiteitsontleding van voermaalgrootte het ʼn beduidende variasie in kumulatiewe opbrengs by growwe maalgroottes van bo P70 = 129 μm getoon. Hierdie variasie is toegeskryf aan verbeteringe in waardemineraalbevryding van flottasietoevoererts uit geslote saamgestelde deeltjies tot die maksimum moontlike teoretiese bevrydingscenario van ten volle bevryde waardemineraaldeeltjies. ʼn Persentasiepuntverbetering van 7.2 in die kumulatiewe algemene opbrengs van waardemineraal en ʼn persentasiepuntverbetering van 2 tot 3 in die verrykingsratio is ook bo die P70 = 250 μmmaalgroottes waargeneem ná verbetering van die bevryding van die waardemineraaldeeltjies van die flottasietoevoererts van ʼn tipiese flottasieaanlegtoevoer tot die maksimum. Die toenames in graad en kumulatiewe opbrengs by growwe groottes is toegeskryf aan verbeteringe in die bevryding van die waardemineraaldeeltjies van die flottasietoevoererts. Op grond van die resultate is daar tot die gevolgtrekking gekom dat toepassing van mikrogolftegnologie groter voordele in stroomaf-verwerking van grofgemaalde ertse sal bied.
327

The geology and ore deposits of a portion of the Harshaw district, Patagonia Mountains, Arizona

Kartchner, Wayne E., 1908- January 1944 (has links)
No description available.
328

Economic geology of the Alamos Mining District, Sonora, Mexico

Vazquez Perez, Adalberto, 1944- January 1975 (has links)
No description available.
329

Flottasie van 'n growwe pirieterts in 'n luggeborrelde hidrosikloon

Burger, Andries Jacobus 12 1900 (has links)
Thesis (MScEng) -- Stellenbosch University, 1986 / ENGLISH ABSTRACT: High turbulence, high shear forces and high centrifugal forces characterise the flow in hydrocyclones. These characteristics are employed advantageously in the air-sparged hydrocyclone so that a space time of only one second is necessary for effective flotation. Conventional flotation processes on the other hand require a few minutes. Flotation of pyrite from a coarse Witwatersrand ore (100% -300 micron; 92% +38 micron) produces a sulphur recovery of 90% with a sulphur grade of 40% in the concentrate when the content of solids of the slurry feed equals 10%. Higher recoveries up to 93% are possible when slurries with a higher content of solids (e.g. 30%) are used. However, the sulphur grade then decreases to about 35%. Flotation in a batch cell produces a recovery of sulphur of 95% with a sulphur grade of 40%, but in this case a flotation time of 5 minutes is required. A hydrocyclone with a diameter of 50 mm and a length of 410 mm produces optimum results at a slurry feed rate of 35 to 40 l/min and an air-flow rate of 200 l/min. An air-flow rate of about 150 l/min is adequate at slurry feed rates lower than 35 l/min. Flotation of particles finer than 38 micron is more successful at higher slurry feed rates. The optimum flotation of coarse particles (i.e. +106 micron) occurs at lower feed rates. The best flotation results are obtained in the size fraction between 38 and 75 micron, which produces a recovery and content of sulphur of 95% and 51% respectively. A collector concentrate of 160 g/ton, which is thrice the quantity used in conventional processes, is required. The best recoveries at slurry feed rates lower than 35 l/min are obtained when the frother concentrate is low (approximately 20 mg/l). A higher frother concentrate, i.e. between 50 to 60 mg/l, is required at higher feed rates. The air-sparged hydrocyclone may be used effectively for rougher flotation and especially for the flotation of ore finer than 150 micron. The use of a specially designed pedestal can minimize blockage of the underflow. Such a pedestal has been designed and tested successfully. / MINTEK
330

Why is information technology failing to support business needs?' : the 'Sishen Iron Ore Mine' story

Bala, Leon Jerzy 03 1900 (has links)
Thesis (MBA)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Sishen Iron Ore Mine produced 24,5 million tons of iron ore during 2000/2001 of which 20 million tons was exported to clients overseas and the rest locally supplied. This production is a mere 2,5% of the world iron ore production. Sishen Iron Ore Mine is planning to produce 26,5 million tons during 2001/2002. The target is to produce more than 30 million tons in the near future. Information technology can only make a positive impact on reaching these goals, when the information technology strategy is aligned with that of the business and the information technology is managed well. This study will indicate red lights in that, if Sishen Iron Ore Mine continues to manage information technology as it has done in the past, the possibility exists that Sishen Iron Ore Mine will not reach the goals agreed upon. This study has, after a thorough investigation, shown where the shortcomings are and how to go about addressing these shortcomings. This study, furthermore, makes certain recommendations towards ensuring that information technology makes a positive impact in assisting Sishen Iron Ore Mine to reach the goals agreed upon. This study has shortly come to the conclusion that there is currently restricted alignment between the information technology strategy and the business strategy, and that the management of information technology does not follow best practice. Research was done and the results gathered pointed to specific shortcomings that needed to be addressed. These shortcomings could be summarised as follows: • Information technology strategy, with specific reference to the questions - Does information technology add value to the business? - Does information technology address business needs? - Why is development costs for information technology solutions so high? • Management of information technology, with regard to - Personnel - Information technology solution priorities - New information technologies - Information technology project management and planning - Management and user awareness and education - Management and user involvement After a thorough investigation of the applicable literature, it is recommended that Sishen Iron Ore mine take certain steps to align the information technology strategy with that of the business, and furthermore, that information technology will be satisfactorily managed. Short conclusions of the recommendations are as follows. • Information technology strategy - To develop a measurement mechanism that will determine the value added by information technology. - To develop thorough user specifications that will address business needs. - To further investigate initiatives to lower development costs for information technology solutions. • Management of information technology - The extension of the current information management organisation to address business needs. - To develop a priority matrix that will prioritise information technology solutions. - To construct forums to ensure that all parties are involved when investigating new information technologies. - To implement a thorough project management and planning environment for information technology projects. - To develop an awareness and education program of information technology for users and managers. - To develop a mechanism that will ensure that users and managers are involved during and after implementing information technology solutions. / AFRIKAANSE OPSOMMING: Die Sishen Ysterertsmyn het gedurende 2000/2001 24,5 miljoen ton ystererts geproduseer waarvan ongeveer 20 miljoen ton uitgevoer is na oorsese kliënte en die res plaaslik geabsorbeer is. Hierdie produksie is maar 'n skamele 2,5% van die wêreld se totale ysterertsproduksie. Die Sishen Ysterertsmyn beplan dan ook om gedurende 2001/2002 26,5 miljoen ton te produseer en binne die nabye toekoms meer as 30 miljoen ton. Inligtingstegnologie kan 'n positiewe bydrae maak tot nastrewing van hierdie doelwitte, indien die strategie daarvan gesinchroniseer is met die Sishen Ysterertsmyn se strategie asook die manier waarop inligtingstegnologie bestuur word. Hierdie studie het ten doeI om met rooi gevaarligte te identifiseer indien die Sishen Ysterertsmyn voortgaan met die bestaande bestuurswyse van inligtingstegnologie wat daartoe kan lei dat die Sishen Ysterertsmyn nie die ooreengekomde doelwitte gaan bereik nie. Hierdie studie het na 'n deeglike ondersoek uitgewys waar die leemtes lê en hoe 'n mens te werk moet gaan om die leemtes aan te spreek. Hierdie studie maak verder aanbevelings om te verseker dat inligtingstegnologie 'n positiewe bydrae kan maak om te verseker dat die Sishen Ysterertsmyn wel die ooreengekomde doelwitte bereik. Hierdie studie het kortliks tot die slotsom gekom dat daar tans beperkte sinchronisering is tussen die strategie vir inligtingstegnologie en die Sishen Ysterertsmyn se strategie en dat die bestuur van inligtingstegnologie nie beste praktyke nastreef nie. Navorsing omtrent die aangeleenthede is gedoen en het uitgewys dat daar spesifieke leemtes is wat aangespreek moet word. Hierdie leemtes behels die volgende: • Strategie vir inligtingstegnologie, met spesifieke verwysing na -of inligtingstegnologie waarde toevoeg tot die Sishen Ysterertsmyn; - of inligtingstegnologie voldoen aan die Sishen Ysterertsmyn se behoeftes; - of die ontwikkelingskoste vir die oplossing van inligtingstegnologie leemtes nie te hoog is nie. • Bestuur van inligtingstegnologie, met verwysing na - personeel; - prioriteite vir oplossing van inligtingstegnologie leemtes; - nuwe inligtingstegnologie; - projekbestuur en beplanning van inligtingstegnologie; - bewusmaking en opvoeding vir bestuur en gebruikers; - bestuur en gebruikers se betrokkenheid. Na 'n deeglike ondersoek met verwysings na verwante literatuur word daar aanbeveel dat die Sishen Ysterertsmyn die nodige stappe moet neem om sinchronisering te verseker tussen die strategie vir inligtingstegnologie en die Sishen Ysterertsmyn se strategie en dat die nodige goeie bestuur van inligtingstegnologie plaasvind. Vervolgens 'n kort samevatting van die aanbevelings met betrekking tot die volgende aspekte • Strategie vir inligtingstegnologie die daarstel van metingsmeganismes om waardetoevoeging van inligtingstegnologie te bepaal; - die opstel van deeglike gebruikerspesifikasies vir die bevrediging van die Sishen Ysterertsmyn se behoeftes; - die ondersoek na inisiatiewe om die ontwikkelingskoste vir die oplossing van inligtingstegnologie gebreke te verlaag. • Bestuur van inligtingstegnologie - die uitbreiding van die bestaande Bestuursinligtingsorganisasie om die Sishen Ysterertsmyn se behoeftes te bevredig; - die daarstelling van prioriteitsmatrikse om oplossing van inligtingstegnologie gebreke te prioritiseer; die daarstelling van forums sodat alle partye betrokke is by die ondersoek na nuwe inligtingstegnologie; - die daarstelling van deeglike projekbestuur en projekbeplanning vir inligtingstegnologie projekte; opvoedingsprogram oor inligtingstegnologie vir bestuur en gebruikers; - die daarstelling van 'n meganisme wat sal verseker dat bestuur en gebruikers meer betrokke raak en bly by die implementering van inligtingstegnologie.

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