No abstract available

[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] The present article is based on a bibliographical analysis of the main applications of the supercritical fluid in various fields, as: extraction from solid matrices, division of liquid charges, chromatography HPLC with supercritical eluent, chemical and biochemical reactions in supercritical solvents etc

No abstract available

[en] The clean up of soils contaminated with petroleum products is associated with several challenges, especially of analytical methodologies and data interpretation. Petroleum products comprise a vast continuum of hydrocarbons from short chain aliphatic and simple aromatic hydrocarbons in gasoline to kerosene, diesel, and heavy oils and to lubricating oils or vaseline, each gradation with increasing carbon chains and complexity. Gasoline alone may contain over twelve hundred compounds. Properties of these vary and this will be of analytical concern. Treatment technology and site remediation progress will lean heavily on analytical techniques that are accurate, reproducible and of real time value. This paper examines the various analytical techniques available along with their special features. Some new methods currently under development are also discussed. These include: (1) High Resolution Chromatograph method which can reveal the detail composition of the contaminants; (2) Supercritical Fluid Extraction which can save time for the analysis; and (3) Fingerprinting which can be used to determine the responsible party for the spill. In addition, the interference due to weathering is also examined

[en] This research thesis aims at a better knowledge of some aspects of the operation of pulsed columns with perforated plates, through a systematic study of the exchange area and of the transfer coefficient. Thus, the author studied the column efficiency and the retention of the dispersed phase. The experimental method of concentration profile has been used. The Miyauchi model has been used to represent the column operation. The number of transfer units and the Peclet number have been determined. In order to precisely determine the value of the exchange coefficient from the definition of the number of true transfer units, the evolution of exchange surface has been studied, based on a photographic determination of droplet diameters in different locations of the column, and of the statistical distribution of these diameters

[en] The experimental determination of process parameters of liquid-liquid extraction is shown. Basic information on various factors influencing the extraction system can be obtained by using radioactive tracers. Examples are presented and discussed. (author)

[en] In this paper, a technique for calculating the stationary transfer of a multicomponent isotopic mixture in squared-off cascades is considered. The proposed method is based on quasi-linearization of the equation system describing the process of multicomponent separation. The transition to relative component concentrations is used to exclude unknown boundary conditions. The suggested method reduces the time of cascade calculation. (orig.)

No abstract available

[en] Liquid-liquid extraction is a method in which the mass transfer of a constituent in solution occurs between two non-totally liquid phases. If we consider a binary solution (A-B) that we have to separate by liquid-liquid extraction: this method requires the introduction of a solvent which extracts preferentially one of the two constituents of the considered solution, for instance A. One of the main application field of this method is the hydrometallurgy and the nuclear industry (separation of metals in solution, treatment of spent nuclear fuels, concentration of solutions without a too important energy supply in opposition to distillation or evaporation). (O.M.)