[en] Starting in 2012 an in crease in the annual throughput from 1.4 to 1.8 millions tons has been projected by the Society of Mine Miraso. This increase is the result of the equipments upgrade works, which have been carried out in 2011 at the crushing plant as well as the heap stacking system. The main changes were associated to the belt conveyors and to the transfer chutes improvements of these two areas. However, the equipments and facilities associated to the agglomeration, leaching and solvent extraction operations were not modified. The objective of this work is to evaluate this new industrial scenario by identifying possible bottlenecks that may slow down the global production process. A study of the treatment capabilities of each main unit is conducted to accomplish this purpose. The evaluation was done in two stages. First of all, an update of the design criteria and the mass balance were performed to establish the Base Case. After that, two alternatives were included to evaluate the impact of the ore treatment increase, in one and two leaching cycles. Aside of the ore throughput increase, the most important changes with impact in the equipments capacities are the utilization reduction of the stacking system (from 80 to 71 %), the increase of the acid application into the agglomerator drum (from 16 to 30 kg/t) and the irrigation rate reduction at the leaching area (from 4.5 to 3.0 1/h/m²). At the agglomeration, the final conclusion is the equipments have the capacity to receive the production increase. However, there are some deviations that need to be corrected, such as the capacity and design of the water and acid injection pipes inside the drum. At the heap leaching area, the irrigation pump system is near the limit of the required capacity (280 m³ /h), so the leaching in two stages could be a solution. Nevertheless, this alternative is recommended as a punctual operational response, in case of an eventual increase in the suspended solids and consequent organic entrainments. Finally, it is recommended to increase the amine concentration at the solvent extraction plant, from 8 to 10%, and thus keep the plant efficiency transfer without to increase the organic flow rate

[en] A mixing-settling apparatus for liquid-liquid extraction comprises a casing. A first partition is mounted along its longitudinal axis and above an overflow device. The mixing device is connected to a means of feeding at least one of the phases and is shaped as at least one hollow element mounted essentially perpendicularly to the longitudinal axis of the casing. The walls of the hollow element are provided with openings, the outlet cross-sections of which are directed to the first partition. The first partition is provided with a means for regulating the height of the layer of the mixed phases M in the mixing zone, said means being located in the partition at the point most distant from the means for feeding phases L, S in the longitudinal direction. A second transporting device is mounted in the settling zone. It is fixed on to the casing and is located after the overflow device in the direction of movement of the light phase l. (author) 10 figs

[en] Gazestan deposit is located at 78 km from eastern of Bafgh (Central Iran) within carbonate rocks, shale, tuff, sandstone and volcanic rocks. Mineralization is the mixture of iron minerals and apatite together with minor quartz and calcite which occurs as various forms mainly in green rocks and rarely in rhyolite. Apatite is fluorapatite and content of Cl is very low. Monazite is the main mineral of gazestan that has been concentrated in apatitie and quarts. Based on assessments and simulation by mining software, the deposit tonnage of ore bodies is about 60 Mt. The grades of Fe, P and TREEs are 26%, 2%, 0.1 %, respectively. The beneficiation studies on a representative sample have been carried out in the lab scale. By operating magnetic separation flow-sheet, it is possible to produce a proper magnetic product containing about 67% Fe. Then Non-magnetic fraction was led to hydrometallurgical study. Finally, the experimental results show that it is possible to produce total rare earth elements product with recovery of about 80% by magnetic separation and hydrometallurgical methods. (author)

[en] The hydrometalation of a carbon-carbon multiple bond is one of the most fundamental and straightforward methodologies for the preparation of new organometallics. Although hydroboration proceeds without any activators, most hydrometalations are promoted by transition metal catalysts. The hydroalumination of olefins catalyzed by titanium or zirconium compounds has been developed as a convenient route to a variety of alkylaluminum compounds, but most of these reactions require long reaction time or elevated temperature. We have demonstrated that monosubstituted olefins can be hydroaluminated with LiAlH₄ in the presence of catalytic amounts of the [C₅(CH₃)₅]₂ZrCl₂ under mild conditions. This reaction is rapid, and gives higher regioselectivity in excellent yields, and involves anti-Markovnikov addition. Further investigations of more useful applications are in progress

[en] Worldwide developments of solvent extraction as applied to hydrometallurgy are described. Uranium and zirconium have been processed in this manner in Canada. (E.C.B.)

No abstract available

[en] The organization of the center of metallurgical studies and the functions carried out by each of its departments are outlined. The handling of data for designing mining metallurgy projects and personnel training is also included. (author)

[en] This paper characterized the microstructure and physical properties of the scale from a uranium mine in Xinjiang by SEM, XRD and FT-IR. Based on the orthogonal experiment design, the formula of HClO₄: EDTA: (NaF + HNO₃) = 4:1:5 is selected. The results show that the scale remover has the functions of dissolution, lattice damage and dispersion. The selected collaborative scale removal method can effectively remove the scale in the uranium mining process and has certain application value. (author)

[en] The new technologies on hydrometallurgy which are described concern operating conditions of acid leaching, solid liquid separation after leaching, and solvents recuperation of uranium. The acid leaching of the pulp obtained from a humid crushing uses sulfuric acid in variable but always in fairly high quantities. This is being due to the loss of free residual acid at the end of the leaching. Indeed, experience shows that a good yield of uranium solubilisation can generally be obtained if the percentage of free acid remains over a determined level. All experiences done in the world to recover this acid by the means of a methodic leaching at counter-current have failed because of filtration problems. This question can be partly solved, if after dry crushing and preheating of the ore, a leaching by S.A. is done at a suitable concentration in order to obtain a thick middle. This technique has been successfully applied at the Arlit plant, operated since 1971 by SOMAIR in the Niger Republic. This technique will also be applied, with minor differences in the Akouta Plant, also in Niger, which is now under studies for the account of COMINAK. The solid-liquid separation and the washing of the pulp by counter-current methodic circulation in a set of decanters shows several disadvantages. They need large quantities of water. They accordingly give very diluted uranium solutions. But the down stream installations for the uranium recuperation, and mainly solvents installation are larger and consequently as costly to build and to operate as uranium content of solution is low. They take a long time and a lot of difficulties to stop and to restart, they cannot be stopped regularly such as at the end of the week. They give a very liquid cake, which needs, for its storage, a failing disposal with high level of security against any accidental losses of liquid to surrounding waters. These troubles can be avoided by a washing and a separation on filters. This technique, which was very difficult and costly year ago when using rotating filters has been largely improved by the use of horizontal bands filters. In most cases, their use improves greatly the concentration operations. This is an already old process. But in this field, many technologies have been developed for improving efficiency. These improvements, as well as the increase of uranium in influents allow to reduce within a great proportion the cost of investments and of exploitation of such solvents installation. At last, very pure concentrates, especially of ammoniac diuranate, can be obtained by judicious arrangement between means of extraction and reextraction. Consequently, it is possible to consider for UF₄ and UF₆ plants a ''short way'' more rapid and less expensive than the ordinary way now used

[en] The selectivity and suitable beneficiation methods for various kinds of uranium ores in China are discussed. Different processing flows for diffeent ores beneficiation and combined ore beneficiation-hydrometallurgy can increase ore feed in hydrometallurgy and the recovery of accompanying elements and reduce the costs of hydrometallurgy. Finally, the author brings out conclusion and suggestion on how to increase economic efficiency of ore deposits