[en] The main purpose of this report is to summarize geochemical modeling studies of the present-day Koongarra groundwaters. Information on the present-day geochemistry and geochemical processes at Koongarra forms a basis for a present-day analogue for nuclear waste migration. The present-day analogue is built on studies of the mineralogy and petrology of the Koongarra deposit, and chemical analyses of present-day groundwaters from the deposit. The overall approach taken in the present study has been to carry out a series of aqueous speciation and state of saturation calculations, including chemical mass transfer calculations, to address the possible control over the chemistry of the present-day for the groundwaters at Koongarra. The most important implication of the present study for the migration of radionuclides is the strong role played by the water-rock interactions, both above and below the water table, influencing the overall chemical evolution of the groundwaters. Thus, the results show that the chemical evolution of waters is strongly controlled by the initial availability of CO₂ and the mineral assemblage encountered, which together determine the major element evolution of the waters by controlling the pH. The relative rates of evolution of the pH and the oxidation state of the groundwaters are also critical to the mobility of uranium. The shallow Koongarra waters are sufficiently oxidising that they can dissolve and transport uranium even under acidic conditions. Under the more reducing condition of the deep groundwaters, is the pH level that permits uranium transport as carbonate complexes. However, if the oxidation state decreases to much lower levels, it would be expected that uranium become immobile. All the speciation and state of saturation calculations carried out in the present study are available from the author, on request

[en] This thesis presents a contribution to the subject of ore technological characterization integrated to orebody context, regarding sample, ore characteristics, ore types definition and distribution through the mineral occurrence, and ore reserves modeling using technological parameters. A professional experience in this specialization based a conceptual discussion of the matter, supported by a practical approach. The initial approach is the subject definition, and it's importance for technological and economical feasibility studies, in all phases of mining research and development, as a tool for beneficiation alternatives definition. The multidisciplinary aspect of the knowledge involved for ore characterization is remarked, considering that is an interface segment to be conduced interactively with others. It is an applied mineralogy, that needs some geological and some ore dressing imputes. After the general considerations about importance and applicability, it follows a methodological approach of laboratory procedures and analytical techniques, as a result of practical experience acquired in the study of several ores. The main points discussed are related with criterion to organized laboratory preparation scheme and to select appropriated analytical techniques, without detailing them, for what some specialized bibliography is indicated. Finalizing the theoretical explanation, there is a concise description about computers resources for 3D orebody modeling, and integrated software applied for geology and mining. For illustration, it is exposed a complex ore case study: niobium mineralization associated with the alkaline-carbonatitic occurrence of Catalao I, located in Goias State, Brazil. Besides the explanation of laboratory procedures and methods applied, results treatment and interpretation are emphasized, under both characterization and economic point of view. (author)

[en] Extensive work has been done in the United States in the estimation of uranium reserves. The government's role in uranium raw materials shifted from support of military programmes to assessing the supply available for commercial power generation. A comprehensive system evolved in which government staff estimated reserves for each property over a range of cost levels using standardized estimation methodology and criteria. The programme was assigned to the Energy Information Administration (EIA) of the Department of Energy in 1983 which has the responsibility for reporting on energy resources. As uranium supply had increased and demand had decreased, there was less concern about the adequacy of resources. In this situation, and with reduced staffing levels, the EIA adopted a two part interim approach to preparing reserve estimates. One used questionnaires to obtain uranium company estimates of their economic and subeconomic reserves, with company determined economic criteria. A second approach modified the earlier detailed government property estimates to account for production. The EIA developed a new system with the assistance of consultants and the uranium industry. The goal of the new system is to produce one set of estimates at various cost categories for each property based on a rigorous adherence to EIA criteria. Initial information is gathered from the industry through a revised annual questionnaire. Company estimates that conform to EIA standards are incorporated into the EIA reserve data base. Additional information is gathered for those estimates requiring clarification, primarily through detailed technical conferences with company staff. The EIA has the capability to prepare independent reserve estimates from basic drill hole data when required. Uranium reserves estimated for 1990 by the EIA include the initial results from the new methodology. The cooperation and support of the uranium industry have been excellent. Detailed evaluation of properties is continuing. Further work is being directed toward improving estimation techniques and analysing production levels obtainable from reserve levels at various cost categories. (author)

[en] Separation of uranium and rare-earth elements from Rirang ore leach solution was carried out through a two-step precipitation. Several condition affecting the separation processes were examined including solution pH, reagent concentration, and reaction prepitation time. Optimum conditions for the first and second precipitation steps include adjustment of precipitation pH to 1.3 and 2.3, respectively by the addition of 7.3% of NH₄OH solution and allowing 60 minutes precipitation/reaction time. Based on the conditions, about 6% of Th, 3% of U, 0.9% of PO₄^3-, and none of RE were recovered in the first precipitation step meanwhile, about 99% of RE, 55% of U, 76% of PO₄^3-, and of the Th were recovered in the second step. (author). 3 refs. 4 tabs. 4 figs

[en] The authors systematically studied the petrology, Sm-Nd isotopic compositions and geochemical characteristics of REE, U, Th, Au elements of Proterozoic groups and Early Paleozoic strata in northwestern Jiangxi and western Zhejiang. It seems that the Proterozoic strata in the east part of South China has low degree of maturity, contains more mantle source materials and belong to greenstone terrane. The Late Proterozoic Sinian-Early Paleozoic strata possesses a great uranium metallogenetic potential. In the east part of South China, to prospect endogenic uranium deposits associated with late tectonomagmatic activity, especially volcanic rock type uranium deposits, has vast vista in the deep fault zone on the Sinian-Paleozoic or granitic basement

[en] Through the analysis of mining practice in the mine No.711, it was found that it was technically feasible to mine the depth of the deposit suffering plenty underground hot water under pressure, and good economic benefits and environmental effects were obtained

[en] In late 1991, the company was changed from SDAG Wismut into a private company (GmbH under German law) with the sole purpose of cleaning up the decommissioned uranium ore mining and dressing plants in such a way that pollutants, contaminated soil, water and air, and other damage to the environment will be removed both from the plant premises and from associated real estate. (orig./HP)

[en] Main commercial-genetic types of the uranium deposits in the CIS are generally described. Uranium ore regions are briefly characterized. Principle peculiarities of the most important deposits are discussed as well as their formation conditions. Main epoches of the uranium mineralization are identified. Uranium resources and their distribution by the eparate commercial-genetic types of deposits are considered

[en] The design of autogeneous grinding mills is difficult because of the variability of their grinding media; when steel balls or rods are used as in SAG or non-autogenous machines, calculations can be much more reliable because--obviously--the characteristics of the media are constant, or predictable. But when the grinding medium and the feed material are one and the same thing, the variations in the physical characteristics of the feed multiply the design problems, especially in the case of autogenous primary mills. Now, however, researchers from Outokumpu, Finland, working backwards after years of studying full scale autogenous production mills, are developing a special laboratory method to test the suitability of ores for Outogenius comminution, Outokumpu's own autogenous grinding process. This paper discusses the results of these new grinding machines which use ores to grind ores. The specifications of the machinery are provided along with the performance on various types of ores

[en] The cessation of uranium mining in Saxony and Thuringia made it a matter of necessity to tackle at short notice the decommissioning of mines and the rehabilitation of mining and milling sites. As the ore was mined in densely populated areas, popular acceptance has to be gained for proposed clean-up. The paper outlines the scope of measures to be taken and conceptual solutions for implementation. (orig.)