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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.
91

Selectivity in Calcium mineral flotation - An analysis of novel an existing approaches / Selektivitet vid flotation av Kalciummineral - En analys av nya och existerande tillvägagångssätt

Karlkvist, Tommy January 2017 (has links)
No description available.
92

X-ray and optical studies on serpentine minerals

Wicks, Frederick John January 1969 (has links)
No description available.
93

The response of alluvial fans and debris cones to changes in sediment supply, upland Britain

Dunsford, Helen Mary January 1999 (has links)
No description available.
94

Historical perspective, current industry practices and the latest developments in public reporting of mineral assests and properties for the extractive industry in South Africa.

Njowa, Godknows 04 March 2008 (has links)
ABSTRACT South Africa had its first democratic elections in 1994. This give rise to a new dimension in social, economic, political and legal fraternities. As result, a number of new rules governing the extractive industry being introduced over the last ten years. The regulatory environment, which affects the public reporting of exploration information, mineral resources and mineral reserves, has undergone major changes. These include:- · The impact of the effects of globalization on the mining industry since many large and small operating mining companies have been listed in more than one country; · Increased regulations introduced by the local JSE as revised listing requirements for reporting and internal controls, not only over financial reporting, but also over the preparation of supplementary information, including mineral resources and mineral reserves statements; and · Development of new international definitions and standards for the estimation and reporting of exploration information, mineral resources and mineral reserves. This due to the international competition for mineral exploration and development projects by global mining companies, which have lead to proactive jurisdictions to establish regulatory regimes with common fabric.. Mineral resource and mineral reserve classification methods, standards and reporting have undergone many changes since the discovery and commercial exploration of minerals as early as the 18th century. To a certain extent, even today there is still ongoing debate regarding the classification systems, definitions and the public reporting of these assets for internal and external use. Over the years, different interpretation, understanding and classification has led to confusion and misunderstanding which resulted in world class reporting scandals including, but not limited to, Bre-X, Shell and Enron. These scandals have highlighted the necessity of standardising the definitions, classification and reporting of mineral assets. The regulators and investors in the mineral industry have also been awakened and have become biggest stakeholders in the development and implementation of these rules in the industry. The concept of “competent person” was introduced and accountability of reporting was moved to the individuals and directors that report these results into the public domain. In this research report the mineral resource and mineral reserve definitions and their developments, historical developments in the minerals industry, current standards and their use in the public reporting of exploration results and mineral assets in the South African context are considered and reviewed in some detail. Included in this report were also areas of possible misconception in the interpretation of categorisation of mineral assets. A practical case study on the Harmony proposal of a hostile take over bid on Goldfields was studied. Information in the public domain on this potential transaction was reviewed during the study, facts were then analysed and formed the basis of an independent opinion. It was concluded that the reporting of mineral assets held by Harmony did not comply with the general reporting principles; hence the report was considered misleading, confusing and materially inconsistent. Hence, in the author’s opinion, Harmony’s offer to Goldfields shareholders was unfair and unreasonable. Given that Goldfields held quality assets compared to Harmony, they should have offered a greater premium for these assets.To be clear and unambiguous, technical and financial information should be published on a comparable basis by all companies operating in the same industry sector, making the same basic assumptions. Public disclosure of mineral resources and mineral reserves is a logical step towards full disclosure of material information because:- 1) mineral resources and mineral reserves are material to all investors; 2) residency or nationality of an investor should not determine what information is disclosed by a company (need for internationally recognised standards); and 3) mineral resources and mineral reserves are required to be considered in impairment and purchase price allocation in accordance with IFRS. Lastly stakeholders in the mining industry should be reminded that the codes and rules are written for guidance of professionals in pursuit of their professional work and it was recommended that large mining firms should establish a mineral resource committee at board level to help and advise the board of directors in decision making.
95

Caracterização petrográfica, química mineral e petrogênese do Kimberlito Alfeu I - Canguçu/RS e uma revisão conceitual de magmatismo e rochas kimberlíticas

Provenzano, Carlos Augusto Silva January 2016 (has links)
O kimberlito Alfeu-I é uma chaminé vulcânica intrusiva na Suíte Pinheiro Machado no domínio Batólito Pelotas, que ocorre na porção leste do Escudo Sul Rio Grandense (ESRG). O corpo apresenta uma forma semicircular com diâmetro ≈20m. As feições texturais e estruturais primárias e a mineralogia encontradas nas rochas deste corpo indicam que, pelo nível de exposição atual, podem ser relacionadas ao fácie diatrema. A rocha é composta por fenocristais e megacristais/macrocristais de composição variada (micas, espinélio, granada, ilmenita e piroxênios), em matriz intersticial com clastos acrescionários (lapilli peletal) e líticos, tanto de autólitos quanto xenólitos do manto e das encaixantes. Ao microscópio ótico possuem textura inequigranular seriada, composta por macrocristais de micas, espinélio, granada e ilmenita; fenocristais de flogopita e microfenocristais de clinopiroxênio e raramente olivina, circundados por matriz afanítica de coloração castanha. Os dados de campo e observações petrográficas permitem classificar o kimberlito Alfeu I como: kimberlito intrusivo e coerente (ICK) (Smith et al. 2008); fácies diatrema – kimberlito tufisítico (Clement; Skinner, 1985); ou kimberlito vulcanoclástico (Mitchell, 1986; 1995). Conforme Mitchell (1995), o corpo é um kimberlito do Grupo II, como mostra a abundância de macro e fenocristais de flogopita A petrografia e mineralogia do Alfeu-I são compatíveis aos kimberlitos do Grupo II. No entanto, a química mineral indica aspectos transicionais entre kimberlitos do Grupo I e II e lamproitos. Ou seja, a petrogênese do Alfeu-I é similar a de outros “magmas mantélicos metassomatizados” potássicos sem forte afinidade com um clã ou grupo particular. Este estudo demonstra que o corpo Alfeu-I compartilha características petrológicas e geoquímicas que podem ser relacionadas aos três tipos de rochas (kimberlitos do Grupo I e II e lamproitos). As conclusões baseadas nas revisões e investigações da química mineral apontaram para composições: (i) transicionais entre kimberlitos do Grupo I – Grupo II – e lamproito; (ii) relacionadas a um manto espinélio lherzolítico associado à piroxenitos e eclogitos; (iii) enriquecidas em profundidades mais rasas que as comuns para magmas “kimberlíticos”; (iv) com pequenas indicações de um manto profundo e remanescente do facie granada lherzolito. Estas conclusões indicam que o magmatismo da formação Serra Geral tem estreita relação com o magmatismo alcalino e recente da porção sul brasileira. / The Alfeu-I kimberlite is an intrusive volcanic chimney in Suite Pinheiro Machado of the Batholith Pelotas domain, which occurs in the eastern portion of the Rio Grande do Sul Shield (ESRG). The body has a semicircular shape with a diameter ≈20m. Textural and primary structural features and mineralogy observed in the rocks of this body indicate that at current exposure level can be related to diatreme facies. The Alfeu-I rock is composed of phenocrysts and megacrystals / macrocrystals of varied composition (mica, spinel, garnet, ilmenite and pyroxene) in interstitial matrix with accreted clasts (lapilli peletal) and lithic, as mantle autoliths and xenoliths and surrounded rocks. In the optical microscope have serial inequigranular texture, composed of mica, spinel, garnet and ilmenite macrocrystals; phlogopite phenocrysts and rarely clinopyroxene and olivine microphenocrystals, surrounded by brown color rocks with aphanitic matrix. The field data and petrographic observations allowed classifying the kimberlite Alfeu-I as: intrusive and coherent kimberlite (ICK) (Smith et al 2008); diatreme facies of kimberlite tuff (Clement; Skinner, 1985); or volcanoclastic kimberlite (Mitchell, 1986; 1995). As Mitchell (1995), the body is a kimberlite Group II type, as shown by plenty of macro and phenocrysts of phlogopite Despite the petrography and mineralogy of Alfeu-I are compatible to kimberlites Group II type, the mineral chemistry indicates transitional points between Group I and II kimberlite and lamproites. It means that the petrogenesis of Alfeu-I is similar to other potassic “magmas from metassomatized mantle” without any strong affinity with a particular clan or group. And demonstrates that the Alfeu I-body shares petrological and geochemical characteristics that can be related to these three types of rocks (kimberlites Group I and II and lamproites). The findings based on the review and investigation of mineral chemistry compositions pointed to: (i) transitional between kimberlites Group I -Group II - and lamproite; (ii) related to a mantle spinel lherzolitic associated with pyroxenites and eclogites; (iii) enriched in shallower depths common to "kimberlitic” magmas; (iv) with minor indications of a deep, remaining mantle lherzolite garnet facie. These findings indicate that the magmatism of the Serra Geral formation is closely related to the alkaline magmatism and recent Brazilian southern portion.
96

Estudo da influência das propriedades de diferentes cargas minerais no poder de cobertura de um filme de tinta

Castro, Carmen Dias January 2009 (has links)
Cargas são compostos minerais quimicamente estáveis, podendo ser extraídas de jazidas, ou obtidas por processos industriais. Devido aos avanços no processamento de cargas minerais, as indústrias estão exigindo cada vez mais produtos interativos com os componentes de formulação. Para tal, torna-se extremamente importante compreender a função das matériasprimas em cada uso industrial específico, gerando, desta forma, produtos sob medida para cada aplicação segundo as necessidades específicas de cada mercado, evitando-se, assim, desperdícios. Dentre os principais setores de compra e consumo de cargas minerais tem-se a indústria de tintas. Sendo um meio bastante competitivo, os fabricantes deste setor estão sempre procurando melhorar seus produtos, resultando na obtenção de uma maior fatia do mercado. Nesse sentido, o presente trabalho, tem como principal objetivo apresentar um estudo baseado na aplicação de cargas minerais na indústria de tintas, buscando contribuir para o entendimento da importância e, do efeito das propriedades físicas, químicas e mineralógicas de diferentes cargas, na formulação de uma tinta, sendo o poder de cobertura do substrato o parâmetro avaliado. Estas tintas são preparadas com uma emulsão de copolímero acrílico e aplicadas para pinturas internas em paredes. O procedimento de otimização foi realizado tendo como base um desenho experimental por um método de mistura nomeado de Simplex segundo Monte-Carlo. Amostras de tinta foram preparadas por reposição de massa da carga original com a mesma massa de três diferentes minerais. Cada uma variou de 0% a 100%. Dois de nove minerais testados são normalmente usados em formulações de tintas no Brasil. Elas são Carbonato de Cálcio Precipitado (PCC) e Carbonato de Cálcio Natural (GCC). A terceira carga foi selecionada entre Caulins (C, SB, PA) Dolomitas (DR,DM), Agalmatolito (A) e Filito (F). Os resultados obtidos mostraram que os três tipos de caulins testados se mostraram mais eficiêntes em relação ao poder de cobertura do que as dolomitas. / The fillers are minerals compounds chemically stable, they can be extracted from ore deposits, or obtained by industrial process. Due to advances on mineral fillers processing, the industry is increasingly requesting interactive products with the formulation components. For that, it is extremely important to understand the functions of the raw materials in each industrial specific use, generating, in this way, products made for each application, second to the specific needs of each market, avoiding material waste. Among the principals buying and consume sectors there is the paint industry. Being a very competitive industry, the manufacturers of this sector are always trying to upgrade his products, resulting in a large market piece obtaining. In this way, the present work main objective is to present a study based on the applications of mineral fillers in the paint industry, looking for contribute for the understanding of the importance and the effect of the physical, chemical and mineralogical properties of different fillers, in formulation of a paint, as the measured parameter was the substrate hiding power. These paints are prepared with acrylic copolymer emulsion and targeted for interior wall paint. The optimization procedure was carried out on the basis of experimental design by a mixture method named Simplex couplet with Monte-Carlo. Paint samples were prepared by replacing the mass of the original filler with the same mass of three different minerals. Each one was varied from 0% to 100%. Two of nine minerals tested were those normally used in the formulation of paints in Brazil. They were Precipitated Calcium Carbonate (PCC), and, Ground Calcium Carbonate (GCC). The third filler chosen was between kaolin, Dolomite (DR,DM), Agalmatolite (A) e Filite (F). The obtained results showed that the tree types of kaolin tested where more efficient than the dolomites in terms of the substrate hiding power.
97

Some techniques for the enhancement of electromagnetic data for mineral exploration.

Sykes, Michael P. January 2000 (has links)
The usefulness of electromagnetic (EM) methods for mineral exploration is severely restricted by the presence of a conductive overburden. Approximately 80% of the Australian continent is covered by regolith that contains some of the most conductive clays on Earth. As a result, frequency-domain methods are only effective for near surface investigations and time-domain methods, that are capable of deeper exploration, require the measurement of very small, late-time signals. Both methods suffer from the fact that the currents in the conductive Earth layers contribute a large portion of the total measured signal that may mask the signal from a conductive target. In the search for non-layered structures, this form of geological noise is the greatest impediment to the success of EM surveys in conductive terrains. Over the years a range of data acquisition and processing techniques have been used in an effort to enhance the response of the non-layered target and thereby increase the likelihood of its detection.The combined use of a variety of survey configurations to assist exploration and interpretation is not new and is practiced regularly. The active nature of EM exploration means that the measured response is determined to a large degree by the way in which the Earth is energised. Geological structures produce different responses to different stimuli. In this work, two new methods of data combination are used to transform the measured data into a residual quantity that enhances the signature of non-layered geological structures. Based on the concept of data redundancy and tested using the results of numerical modelling, the new combinations greatly increase the signal to noise ratio for targets located in a conductive environment by reducing the layered Earth contribution. The data combinations have application to frequency-domain and time-domain EM surveys and simple ++ / interpretive rules can be applied to the residuals to extract geological parameters useful in exploration. The new methods make use of inductive loop sources and can therefore also be applied to airborne surveys.Airborne surveys present special difficulties due to the data acquisition procedures commonly used. Flight-line related artefacts such as herringbones detract from the appearance of maps and make boundary definition more difficult. A new procedure, based on the Radon transform, is used to remove herringbones from airborne EM maps and locate the conductive boundaries correctly, making interpretation more reliable and easier. In addition, selective filtering of the Radon transform data enables the enhancement or attenuation of specific linear features shown in the map to emphasise features of interest. Comparison of the Radon transform procedures with the more conventional Fourier transform methods shaves the Radon transform processing to be more versatile and less prone to distortion of the features in a map.The procedures developed in this work are applied to field data with good results.
98

Fibroblast growth factor 23, mineral metabolism and mortality among elderly men (Swedish MrOs)

Westerberg, Per-Anton, Tivesten, Åsa, Karlsson, Magnus, Mellström, Dan, Eric, Orwoll, Ohlsson, Claes, Larsson, Tobias, Linde, Torbjörn, Ljunggren, Östen January 2013 (has links)
Background: Fibroblast growth factor 23 (FGF23) is the earliest marker of disturbed mineral metabolism as renal function decreases. Its serum levels are associated with mortality in dialysis patients, persons with chronic kidney disease (CKD) and prevalent cardiovascular disease (CVD), and it is associated with atherosclerosis, endothelial dysfunction and left ventricular hypertrophy in the general population. The primary aim of this study is to examine the association between FGF23 and mortality, in relation to renal function in the community. A secondary aim is to examine the association between FGF23 and CVD related death. Methods: The population-based cohort of MrOS Sweden included 3014 men (age 69-81 years). At inclusion intact FGF23, intact parathyroid hormone (PTH), 25 hydroxyl vitamin D (25D), calcium and phosphate were measured. Mortality data were collected after an average of 4.5 years follow-up. 352 deaths occurred, 132 of CVD. Association between FGF23 and mortality was analyzed in quartiles of FGF23. Kaplan-Meier curves and Log-rank test were used to examine time to events. Cox proportional hazards regression was used to examine the association between FGF23, in quartiles and as a continuous variable, with mortality. The associations were also analyzed in the sub-cohort with estimated glomerular filtration rate (eGFR) above 60 ml/min/1.73 m(2). Results: There was no association between FGF23 and all-cause mortality, Hazard ratio (HR) 95% confidence interval (CI): 1.02 (0.89-1.17). For CVD death the HR (95% CI) was 1.26 (0.99 - 1.59)/(1-SD) increase in log(10) FGF23 after adjustment for eGFR, and other confounders. In the sub-cohort with eGFR > 60 ml/min/1.73 m(2) the HR (95% CI) for CVD death was 55% (13-111)/(1-SD) increase in log(10) FGF23. Conclusions: FGF23 is not associated with mortality of all-cause in elderly community living men, but there is a weak association with CVD death, even after adjustment for eGFR and the other confounders. The association with CVD death is noticeable only in the sub-cohort with preserved renal function.
99

Preliminary equipment selection analysis of mining shovels and haulage trucks

Bares, John Alvin, 1951- January 1987 (has links)
No description available.
100

Optimum loading and haulage systems

Davis, Joe Brooks, 1930- January 1961 (has links)
No description available.

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