[pt] No litoral brasileiro, do Rio Grande do Norte até Rio de Janeiro, se encontram os mais importantes depósitos de areias monazíticas No litoral do Município de São Francisco de Itabapoana, no estado de Rio de Janeiro, encontram-se importantes jazidas de areias monazíticas, e na vila de Buena, situada neste município, se encontra uma usina de beneficiamento de areias monazíticas. Nela são obtidos concentrados de ilmenita, zirconita, rutilo e monazita utilizando separadores letrostáticos, eletromagnéticos e gravimétricos (espirais, planos inclinados e mesas vivratorias). Com o objetivo de caracterizar a exposição dos habitantes desta vila a partículas de poeira na fração respirável foram coletadas amostras de aerossóis usando impactadores em cascata, amostradores portáteis com ciclone e amostras de bioindicadores. As amostras foram analisadas pelo método PIXE (Particle Induced X ray Emission) para determinação da concentração dos metais e do MMAD (Mass Median Aerodinamic Diameter), por PDMS (Plasma Desorption Mass Spectrometry) para identificação dos compostos presentes. As amostras de aerossóis coletadas com amostradores portáteis e de bioindicadores foram analisadas para determinação da concentração dos isótopos das séries naturais do tório e urânio. Os resultados indicam que os habitantes estão expostos a partículas contendo metais na fração respirável do aerossol geradas por fontes tanto antropogênicas , quanto naturais. As amostras de bioindicadores indicam os habitantes da vila tem estado expostos a radionuclídeos das séries naturais do tório e urânio nos últimos 15 anos. / [en] The main deposit of mineral sands in Brasil occur from the Rio Grande do Norte State to Rio de Janeiro State. The main commercial deposit is located in Buena, a village at São Francisco de Itabapoana, Rio de Janeiro State. In buena there is a plant that process minerals sands to obtain ilmenite, zirconite, rutile and monazite concentrates. This plant belongs to the Industrias Nucleares Brasileiras (INB). Close to this plant there is a small village. Aerosols samples were collected using cascade impactors and cyclones in order to characterize human exposure to airborne particles in the respirable fraction. Lichens samples were also collected. The samples were analyzed by PIXE (Particle Induced X ray Emission) for determination of elemental mass concentration and MMAD (Mass Median Aerodynamic Diameter). PDMS (Plasma Desorption Mass Spectrometry) allows the identification of the chemicals compounds present in the samples. The concentrations of radionuclides from the thorium and uranium natural series were also determined. The results show that the inhabitants were espoused to airborne particles in the respirable fraction of aerosols from natural and anthropogenic sources. The lichens samples indicate that the inhabitants have been exposed to radionuclides from the thorium and uranium natural series since last 15 years.

The objective of the treatise is to review the sample methodology and the exploration methods at a heavy mineral sands deposit. The level of confidence and the risk associated with the resource calculations will be established based on the sample methodology. Two drilling methods used at Hillendale are compared statistically and visually. It is clear from the comparison that the Wallis Aircore (WAC) method is significantly better than the Reverse Circulation (RCN) method. This is evident also when comparing results of the two methods with the recovery from the mined out areas. The WAC drilling method reduces the risk of downhole contamination due to the change in the drilling method allowing air to be forced back in an inner tube after the sample is collected compared to the air blowout of the RCN method. The WAC method reduces the variability introduced in the sample collection as compared to the RCN method. The average calculated value (for total heavy minerals (THM) and Ilmenite) of the global population for the two methods is similar. The reduced variability in the sample population of the WAC method results in a lower population being required for the confidence interval about the mean at a 95% confidence level. The lower number of required samples results in a lowering of project cost. Blockmodels created from the two drilling methods are compared statistically (mode, median, standard deviation). The global mean of the input data compares well with the global mean of the estimated blockmodel. In reconciling the resource blockmodels with actual production data, the variability as introduced by the RCN drilling method is clear. The WAC drilling information produces a blockmodel with an acceptable level of variance (deviation of the geological model from the actual values obtained during mining) as defined by Hillendale mine management of less than 10%. This is determined by reconciling the estimated geological blockmodel for a specific mined out area against the actual tonnages and plant recovery values achieved in the same area. Ultimately, because the drill spacing is standard in the mining operation under study, the required confidence in the mean might not be achieved by either of the two drilling methods in certain portions of the mine, but the results from the WAC method will be closer to the reality than the RCN method with the same number of drillholes. Three main risks are identified in the sample methodology; they have a high probability to occur or have a high cost impact. The risk inherent in sampling and analysis is the most important of the risks identified in this study. The risk can be effectively reduced by implementing a quality assurance and quality control programme (QAQC). The other high risks are introduced by the drilling method and drillhole spacing. The risk can be reduced by continuous improvement and keeping up to date with new developments in the industry such as improved drilling techniques and by improved knowledge of the ore-body. The knowledge will help in understanding the risk - It may become clear in the text how this can reduce the risk. In conclusion, the improvement and implementation of systems such as improved drilling technique and quality assurance and quality control programmes enables one to establish an acceptable confidence level in the resource calculation as well as reducing the inherent risk to an acceptable level for future decisions. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Geology / unrestricted