As discrepâncias nos resultados de análises de materiais informados tanto pelo produtor quanto pelo consumidor são um problema comum na maioria das indústrias. Os contratos comerciais na indústria mineral normalmente penalizam o produtor quando uma determinada caraterística do minério exceder os limites estabelecidos. As diferenças nos resultados de análise são devidas a muitas formas de erro. Contratos rígidos impõem ao minerador o emprego de um rigoroso programa de controle de qualidade e nestas situações a amostragem possui um papel fundamental. Esta tese tem por objetivo propor um novo protocolo de amostragem e preparação de amostras que garanta a representatividade desejada pelas partes, produtor e consumidor. O estudo inicia fazendo-se uma abordagem qualitativa da amostragem, sendo enfocados os conceitos de representatividade e amostragem probabilística. É feita uma apresentação dos tipos de erros existentes em um protocolo amostral e são apresentados exemplos de problemas que ocorrem devido à falta de cuidado no dimensionamento e operação de amostradores e durante o processo de preparação da amostra. A seguir, é efetuada uma abordagem quantitativa da amostragem onde é apresentado o equacionamento matemático da teoria da amostragem de Gy. Tendo em vista as diferenças de resultados que usualmente ocorrem entre laboratórios é introduzida uma metodolo gia para a verificação da equidade destas determinações através do estudo de alguns casos. A definição do novo protocolo de amostragem foi baseada na teoria da amostragem de Gy. Para tanto, foi realizado o estudo de quatro casos com a finalidade de confirmar os princípios mais importantes da teoria da amostragem Nos ensaios foram realizadas a medição do erro total da amostragem em pilha e a verificação da existência de significância estatística deste erro em relação à disposição do carvão no depósito, foi realizada a verificação da significância do erro total na amostragem mecânica probabilística, a verificação das etapas mais críticas do processo de preparação de amostras, a determinação do erro de integração dos vários tipos de carvões testados e foi verificada a aplicabilidade da análise variográfica para a determinação do erro de integração. Os resultados encontrados mostraram a validade dos conceitos empregados pela teoria da amostragem e indicaram a impropriedade das normas brasileiras de amostragem e preparação de carvão, NBR 8291 e 8292, para garantir a representatividade da caracterização de um determinado lote de carvão. É proposto um novo protocolo de amostragem de carvão mineral, o qual leva em consideração a variabilidade das partículas componentes do lote e as formas de amostragem e preparação da amostra. Conclui-se que é possível dimensionar um sistema de controle de qualidade do carvão que seja capaz de estimar a precisão desejada e que garanta a representatividade do resultado acordada entre as partes. Por fim, é sugerida a modificação das normas brasileiras existentes.

Os efeitos provocados por radiações são conhecidos na literatura por meio dos estudos em usinas nucleares e em testes bélicos. Entretanto, os efeitos da radiação natural vêm despertando a atenção das autoridades da saúde, dentre as quais se destaca a Environmental Protection Agency (EPA) nos Estados Unidos e a National Radiological Protection Board (NRPB) no Reino Unido. Os efeitos epidemiológicos ocasionados por radiação de origem natural, mais especificamente a radiação emanada pelo gás radônio que fica acumulado em residências enclausuradas por muito tempo, tem sido alvo de intensas investigações. Nessa dissertação, foi realizada uma avaliação ambiental preliminar da radiação natural devida ao radônio como elemento epidemiológico no Escudo Sul-riograndense. Os dados utilizados para determinar o risco epidemiológico foram: neoplasias, radiação, geologia e população. O banco de dados dos casos de óbitos por neoplasias do estado foi obtido da Secretaria da Saúde, por meio do Núcleo de Informação em Saúde. A radiação natural devida ao radônio foi determinada a partir dos dados gamaespectrométricos obtidos de levantamento aerogeofísico da CPRM no Escudo Sul-riograndense, nos projetos Camaquã e Extremo Sudeste do Brasil realizados nos anos de 1973 e 1978, respectivamente. Os dados geológicos foram obtidos do Mapa Geológico do Estado de 1989. Os dados de população foram obtidos junto ao Instituto Brasileiro de Geografia e Estatística (IBGE). A integração de dados foi realizada usando a metodologia de matriz de sobreposição entre os dados de casos de óbitos por neoplasia e de gamaespectrometria. Os dados de população foram empregados para normalizar os dados de neoplasias, e o dado de geologia para correlacionar com a gamaespectrometria. Os resultados da integração são mapas classificados pelo grau de risco epidemiológico, nos quais é apresentada a relação entre os casos de neoplasias pela intensidade de radiação devida ao radônio. Nesse sentido, uma boa relação foi assinalada e são recomendados estudos adicionais sobre esse mesmo banco de dados. / The radiation effects on human beings are known from studies carried out on nuclear power plants and nuclear tests. However, the radiation effects due to natural radiation have being recently considered on health agencies, such as U.S.A. Environmental Protection Agency (EPA) and United Kingdon National Radiological Protection Board (NRPB). The epidemiological character due to natural radiation, mainly that regarded to radon emanation, has being investigated in last years, because the radon gas is accumulated in closed houses. This master dissertation is devoted to a preliminary evaluation of natural radon emanation as an epidemiological element in the sul-riograndense shield. The data used in this evaluation are: cancer deaths, natural radiation, geology and population. Just special types of cancer deaths were considered in this evaluation and the data were made available from Núcleo de Informação em Saúde of the Health State Secretary (Rio Grande do Sul). The natural radiation due to radon was determined from an aerogoephysical survey (gamaspectrometric) carried out during 1973 (Camaquã Project) and 1978 (Extremo Sudeste do Brasil) by the Geological Survey of Brazil (CPRM). The geological data is from Rio Grande do Sul geological map, published in 1989. The population data was obtained from Instituto Brasileiro de Geografia e Estatística (IBGE). The data integration was performed through matrix of superposition method. The main input data were cancer deaths and natural radon emanation (gamaspectrometric data). The population data was used in order to normalize the cancer deaths original data. The gamaspectrometric data was used to achieve a better correlation with geological map. The results of data integration procedures are maps classifying epidemiological risk in the Sulriograndense Shield, in which the relation between cancer deaths and radon emanation intensity are shown. In this way, a good correlation is shown and additional studies are recommended.

acase@tulane.edu / 1 / YD

No description available.

Abstract In order to improve the optimisation of mineral processing operations the rheological properties of slurries must be determined as accurately as possible under the conditions that closely resemble actual site conditions. The rheology of particles suspended in Newtonian fluids is well documented. However, the rheology of particles in non-Newtonian fluids has not been the subject of much investigation till now. The work conducted here attempts to fill this gap in knowledge. The rheological properties of slurries are heavily dependent on the solids concentrations and particle-solid interaction. At low solids concentrations, constant viscosity and Newtonian behaviour is observed, but as solids concentration increases the rheological behaviour becomes increasingly complex and non-Newtonian with viscosity becoming dependent on the shear rate. The nature of the non-Newtonian behaviour depends on the solid concentration, particle shape, particle size, particle size distribution and the suspending liquid rheological properties. The suspension/slurry may develop a yield stress and become time dependent in nature as structures develop within the fluid at higher solids concentrations. This study however, is primarily focused on the measurement of the rheological properties, where it is assumed that the fluid will be fully sheared and that the rheological properties will be unlikely to change with time. Shear thickening behaviour of slurries was the focus of this work. The aim was to investigate the slurry concentration region where shear thickening occurs. The first objective of the project was to develop a fluid analogue which will have similar rheological behaviour to that of concentrated tailings from gold mines so that it can be used as a test material to simulate the flow behaviour of the tailings in a pipe. The second objective of this project was to enable the prediction of flow behaviour in the pipe loop under certain conditions using the fluid analogue for slurry from Sunrise dam. In order to achieve the objectives, experiments were carried out to obtain a fluid analogue of a shear thickening slurry. CSL 500 and SR 200 rheometers were used for the characterisation of different fluid analogues and shear thickening mineral slurries. Malvern Sizer, model: mastersizerX v1.1, was used to obtain particle size distributions. A mini pipe loop system, located in the laboratory of the Rheology and Materials Processing Centre (RMPC) was used to get pipe line flow data for comparison with the rheometer data. A few fluid analogues with different suspending medium and different concentrations of glass spheres was tested before finally using, 48 vol% glass spheres in 1.8 wt% CMC solution as a fluid analogue for the mineral tailings obtained from Sunrise dam, WA. For comparison between the pipe line and rheometer data, all pipe line data (in the form of 8V/D) were converted to rheometer data (in the form of du/dr) using the Robinowitsch-Mooney equation. The above comparison indicated that it is possible to produce fluid analogue to simulate the flow behaviour of Sunrise dam slurry using a shear thinning suspending medium with high concentration of glass particles. Shear thickening flow behaviour was clearly observed in the rheometer while it was less predominant in a pipe line flow.

Typescript / 2 v. : ill. app'xes, 5 maps in end pocket / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Economic Geology, 1966

Disturbances in mineral metabolism contribute to vascular calcification and mortality risk in chronic kidney disease (CKD). Serum levels of fibroblast growth factor (FGF)23, a bone derived, phosphaturic peptide, are associated with cardiovascular mortality in CKD. Membrane bound klotho(KL) is an obligate co receptor for FGF23 signaling in the kidney. To study aspects of FGF23 in mild to moderate impairment of renal function we have analyzed FGF23, estimated glomerular filtration rate (eGFR), parathyroid hormone(PTH), 1,25 (OH)2 vitamin D (1,25D), calcium and phosphate in one patient with a FGF23 producing tumor, before and after tumor removal (study 1), in 72 CKD patients with varying degree of renal dysfunction (study 2), in 9 healthy kidney donors, before and after nephrectomy (study 3). We also analyzed FGF23 (study 4), and performed genotyping of 27 single nucleotide polymorphisms (SNP) of the KL gene (study 5) in 2838 elderly Swedish men (MrOs study) and examined the association with mortality. FGF23 normalizes in 30-45 minutes after removal of a FGF23 producing tumor (study 1). 1,25D increases in hours and remains elevated months, even when the other parameters have normalized. FGF23 increase early in CKD, initially slowly, in correlation with PTH, but exponentially when hyperphosphatemia ensues (study 2). After unilateral nephrectomy (study 3) mineral homeostasis remain stable, initially due to a rise in PTH and later to an increase in FGF23. FGF23 levels are not correlated with mortality in elderly men after adjustment for eGFR, but with mortality due to cardiovascular disease, even in persons with normal eGFR (study 4). Polymorphism of the KL gene do not correlate with increased mortality risk in elderly men (study 5), but there is a modulating effect on FGF23 levels. FGF23 is of importance in maintaining phosphate homeostasis as renal function declines. It is co regulated with PTH until advanced renal dysfunction, and adjust the 1,25D to the actual GFR. FGF23 is associated with cardiovascular mortality. Further studies are needed to determine the mechanism, and if reduction of FGF23 by reducing phosphate intake may be beneficial even in persons with mild to moderate renal function.

Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry serves as a sensitive non-destructive characterization technique that can elucidate intrinsic physical properties, taking advantage of the superparamagnetic behaviour that nanoparticles may exhibit. In this work, synthetic analogues of common iron oxyhydroxide minerals (ferrihydrite, goethite, lepidocrocite, schwertmannite and akaganéite) are characterized using DC and AC magnetometry (cryogenic, room temperature), along with complementary analyses from Mössbauer spectroscopy (cryogenic, room temperature), powder X-ray diffraction and scanning electron microscopy. It was found that all of the iron oxyhydroxide mineral nanoparticles, including lepidocrocite, schwertmannite and akaganéite were superparamagnetic and therefore magnetically ordered at room temperature. Previous estimates of Néel temperatures for these three minerals are relatively low and are understood as misinterpreted magnetic blocking temperatures. This has important implications in environmental geoscience due to this mineral group’s potential as magnetic remanence carriers. Analysis of the data enabled the extraction of the intrinsic physical parameters of the nanoparticles, including magnetic sizes. The study also showed the possible effect on these parameters of crystal-chemical variations, due to elemental structural incorporation, providing a nanoscale mineralogical characterization of these iron oxyhydroxides. The analysis of the intrinsic parameters showed that all of the iron oxyhydroxide mineral nanoparticles considered here have a common magnetic moment formation mechanism associated with a random spatial distribution of iv uncompensated magnetic spins, and with different degrees of structural disorder and compositional stoichiometry variability, which give rise to relatively large intrinsic magnetization values. The elucidation of the magnetic nanostructure also contributes to the study of the surface region of the nanoparticles, which affects the particles’ reactivity in the environment.

Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry serves as a sensitive non-destructive characterization technique that can elucidate intrinsic physical properties, taking advantage of the superparamagnetic behaviour that nanoparticles may exhibit. In this work, synthetic analogues of common iron oxyhydroxide minerals (ferrihydrite, goethite, lepidocrocite, schwertmannite and akaganéite) are characterized using DC and AC magnetometry (cryogenic, room temperature), along with complementary analyses from Mössbauer spectroscopy (cryogenic, room temperature), powder X-ray diffraction and scanning electron microscopy. It was found that all of the iron oxyhydroxide mineral nanoparticles, including lepidocrocite, schwertmannite and akaganéite were superparamagnetic and therefore magnetically ordered at room temperature. Previous estimates of Néel temperatures for these three minerals are relatively low and are understood as misinterpreted magnetic blocking temperatures. This has important implications in environmental geoscience due to this mineral group’s potential as magnetic remanence carriers. Analysis of the data enabled the extraction of the intrinsic physical parameters of the nanoparticles, including magnetic sizes. The study also showed the possible effect on these parameters of crystal-chemical variations, due to elemental structural incorporation, providing a nanoscale mineralogical characterization of these iron oxyhydroxides. The analysis of the intrinsic parameters showed that all of the iron oxyhydroxide mineral nanoparticles considered here have a common magnetic moment formation mechanism associated with a random spatial distribution of iv uncompensated magnetic spins, and with different degrees of structural disorder and compositional stoichiometry variability, which give rise to relatively large intrinsic magnetization values. The elucidation of the magnetic nanostructure also contributes to the study of the surface region of the nanoparticles, which affects the particles’ reactivity in the environment.

Equine gastric ulcer syndrome (EGUS) has been reported to occur in 40% to over 90% of horses across multiple equestrian disciplines. The objective of this study was to evaluate the effect of trace mineral supplementation on gastric ulcers in exercising yearling horses. Twenty-one Quarter Horse yearlings, 15 to 18 mo of age, were randomly assigned to 1 of 3 treatment groups. The control group received no supplemental trace minerals, the inorganic group received supplemental sulfated trace minerals, and the organic treatment received supplemental amino acid complexed trace minerals. The trial consisted of 3 consecutive 28-d periods, separated by 5 d of diet acclimation. The basal ration included a 14% CP textured concentrate, with coastal Bermudagrass hay fed in Periods 1 and 3 and alfalfa consumed in Period 2. In Periods 1 and 2, horses were exercised on a mechanical horse-exerciser, but were lunged or underwent training in an undergraduate course in Period 3. At the end of each period, horses were transported for 6 h, 5 d before being endoscopically examined to assign ulcer scores. Data were analyzed as repeated measures using the mixed procedure of SAS, with the model including fixed effects of treatment, period, and their interaction (SAS 9.2). All P-values < 0.05 were considered significantly different. Baseline EGUS scores were not different among treatment groups, with a mean of 2.1. There was no effect of treatment in any period, or a period by treatment interaction. There was a significant period effect (P < 0.01). Mean ulcer scores in Periods 1, 2, and 3 were significantly lower than baseline, with mean scores of 1.5, 1.0, and 1.5, respectively. There was a tendency (P=0.06) for mean ulcer scores to be lower in Period 2 than in Periods 1 and 3, which were not different. Average daily intakes of Zn, Mn, Cu, and Co were significantly higher in the organic and inorganic than control horses (P < 0.0001). Under the conditions of this study, trace mineral supplementation did not affect gastric ulcer appearance and severity. However, it is possible that dietary and management alternatives, such as hay and concentrate types, could be anti-ulcerogenic.