This project aims to quantify natural gamma radiation in gold tailings disposal facilities (TDFs) relative to uranium concentration data in order to use natural gamma detection methods as alternative methods for uranium resource estimation modelling in gold tailings. Uranium migration within the New Machavie TDF was also investigated as migration affects both the grade of the TDF as a uranium resource and poses a threat to the environment. In order to determine the most appropriate radiometric testing procedure, various methods were employed for natural gamma detection, including surface natural gamma spectrometry, borehole natural gamma spectrometry and scintillometry, as well as incremental sampling. These measurements were then statistically compared to ICP-MS analyses to find the best method, and then modelled to apply volumetric resource estimation procedures. The oxidation reduction potential was also tested as uranium geochemistry is dependent on oxidation for mobilisation. Furthermore, leaching tests were employed to relate specific anions as a mode of transportation in solution. Results indicated that down-hole natural gamma spectrometry performed the best and that 2376.87 kg of uranium is present in the TDF. Migration modelling indicated that uranium is mobilised away from the oxidized top area of the TDF and that accumulation occurs in the saturated zone of the TDF under a reducing environment. Sulphate anions as the result of pyrite oxidation are primarily responsible for the mobilisation as radionuclides in New Machavie. The results of this project can be applied to the resource estimation of all uranium bearing tailings facilities prior to re-mining as a means to decrease exploration costs and to accurately model the distribution of uranium. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

This project aims to quantify natural gamma radiation in gold tailings disposal facilities (TDFs) relative to uranium concentration data in order to use natural gamma detection methods as alternative methods for uranium resource estimation modelling in gold tailings. Uranium migration within the New Machavie TDF was also investigated as migration affects both the grade of the TDF as a uranium resource and poses a threat to the environment. In order to determine the most appropriate radiometric testing procedure, various methods were employed for natural gamma detection, including surface natural gamma spectrometry, borehole natural gamma spectrometry and scintillometry, as well as incremental sampling. These measurements were then statistically compared to ICP-MS analyses to find the best method, and then modelled to apply volumetric resource estimation procedures. The oxidation reduction potential was also tested as uranium geochemistry is dependent on oxidation for mobilisation. Furthermore, leaching tests were employed to relate specific anions as a mode of transportation in solution. Results indicated that down-hole natural gamma spectrometry performed the best and that 2376.87 kg of uranium is present in the TDF. Migration modelling indicated that uranium is mobilised away from the oxidized top area of the TDF and that accumulation occurs in the saturated zone of the TDF under a reducing environment. Sulphate anions as the result of pyrite oxidation are primarily responsible for the mobilisation as radionuclides in New Machavie. The results of this project can be applied to the resource estimation of all uranium bearing tailings facilities prior to re-mining as a means to decrease exploration costs and to accurately model the distribution of uranium. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

[pt] Este trabalho propõe um modelo de cálculo das probabilidades de mobilidade dinâmica e um modelo de mobilidade, que é aplicado a um método de controle de admissão de chamadas para sistemas móveis celulares, denominado shadows cluster. Este método busca priorizar chamadas que estejam em handoff em relação a novas chamadas. O objetivo desta técnica é uma melhor qualidade para uma chamada em andamento, evitando-se a queda da ligação. O objetivo do modelo proposto é reduzir a carga de sinalização do sistema celular, comparada à obtida na ausência desse modelo. Resultados de simulações mostram que este objetivo do método do shadow cluster pode ser atingido para vários cenários de mobildade. / [en] This work proposes a Dynamic Mobile Probability model and a mobility model, which is applied for a call admission control scheme for mobile cellular systems, called shadow cluster. This scheme gives priority to calls that are in handoff procedure. The objective of this scheme is a better call in progress quality, avoiding the call dropping. The objective of the proposed model is to reduce signalling load of cellular system. Simulation results show that indeed those objectives can be achived.

The Impala Platinum Mines are located in the western limb of the Bushveld Complex. The economic platinum mineralization which is currently being mined at Impala Platinum occurs in the Merensky and the Upper Group 2 (UG2) Reefs. These ore bearing horizons are stratigraphically located in the Upper Critical Zone of the Bushveld Complex. Due to the variable stratigraphic distance between the UG2 Chromitite Layer and the Merensky Reef, each of these reef horizons is influenced by different geological structural features. It has been observed on several shafts that there is no direct correlation between geological structures encountered on the Merensky Reef to that seen on the UG2 Reef horizon. This observation was prevalent during the geological structural evaluation of the two reef horizons in the No. 12 Shaft area. The Merensky Reef presented itself geologically more favorable to the UG2 Chromitite Layer in terms of structural complexities. Other positive factors included global supply and demand for the resultant metals and the encouraging metal price. There was nonetheless limited trial mining of the UG2 Reef within the No. 12 Shaft area. However, as a result of unfavorable market conditions at the time and complicated geological features which would result in very low extraction rates, it was decided to temporarily cease all mining operations related to the UG2 Reef horizon in this area. It has been strongly recommended in previous geological evaluation reports that the UG2 Chromitite Layer in the No. 12 Shaft area be appraised in significant detail in order to determine the possibility of economically exploiting this mineralized horizon. Due to the current favorable economic climate for platinum group metals, it was suggested by senior management that the UG2 Chromitite Layer be re – evaluated. This dissertation discusses some of the investigative research which was conducted during this re - assessment. The project work comprised research in the following aspects, exploratory drilling, interpretation of geological structural data, grade estimation, mineral resource estimation, financial and sensitivity analyses and aspects concerning risk management. Throughout the project all the input parameters and resultant calculations related to grade, mineral resource and reserve, financial and sensitivity analyses were based on tentative estimates which reflect the author’s personal opinions and assumptions. It is not absolute data of Impala Platinum and thus does not in any way reflect the views of the company. The UG2 Chromitite Layer in the No. 12 Shaft area was benchmarked against the neighboring shafts in terms of its geological and metallurgical characteristics. It was found that regionally, the UG2 Reef displays very limited variability. The financial assessment based on average market input data and assumptions have revealed positive results with regards to general financial and marketing decisions and strategies. In the risk assessment, the high impact risks generally facing all mining companies were found to be within manageable levels. From the investigative geological research based on general business decision criteria, market averages, estimations and assumptions which are used to broadly evaluate projects in the mining industry, it has been demonstrated that it would be economically viable to mine the UG2 Chromitite Layer in the No. 12 Shaft area of Impala Platinum. / Dissertation (MSc (Earth Science Practice and Management))--University of Pretoria, 2008. / Geology / unrestricted

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Minestis software allows geological domain modeling and resource estimation through an efficient and simplified geostatistics-based workflow. It has been designed for all those, geologists, mining engineers or auditors, for whom quick production of quality models is at the heart of their concerns.

Minestis software allows geological domain modeling and resource estimation through an efficient and simplified geostatistics-based workflow. It has been designed for all those, geologists, mining engineers or auditors, for whom quick production of quality models is at the heart of their concerns.

In recent years nickel is mostly produced from lateritic ore deposits such as nontronite, limonite, etc. Resource estimation is difficult for laterite deposits as they have a weak and heterogeneous form. 3D modeling software are rather suitable for deposits having tabular or vein type ores. In this study the most appropriate estimation technique for resource estimation of nickel laterite deposits was investigated. One of the known nickel laterite deposits in Turkey is located at T&uuml / rkmen&ccedil / ardagi - G&ouml / rdes region. Since the nickel (Ni) grade recovered from drilling studies seem to be very low, a reconciliation pit having dimensions of 40 m x 40 m x 15 m in x-y-z directions was planned by Meta Nikel Kobalt Mining Company (META), the license owner of the mine, to produce nickel ore. 13 core drilling and 13 reverse circulation drilling (RC) and 26 column samplings adjacent to each drillholes were located in this area. Those three sampling results were compared to each other and as well as the actual production values obtained from reconciliation pit. On the other side 3D computer modeling was also used to model the nickel resource in T&uuml / rkmen&ccedil / ardagi - G&ouml / rdes laterites. The results obtained from both inverse distance weighting and kriging methods were compared to the results of actual production to find out the applicability of 3D modeling to laterite deposits. Modeling results showed that Ni grade of the reconciliation pit in T&uuml / rkmen&ccedil / ardagi - G&ouml / rdes, considering 0.5% Ni cut-off value, by using drillholes data, inverse distance weighting method estimates 622 tonnes with 0.553% Ni and kriging method estimates 749 tonnes with 0.527% Ni. The actual production pit results provided 4,882 tonnes of nickel ore with 0.649% Ni grade. These results show that grade values seem to be acceptable but in terms of tonnage, there are significant differences between theoretical estimated values and production values.