Chile has seven copper smelters, four that are linked to primary producers (three owned by Codelco and one by Disputada) and three custom smelters (two owned by Enami and one by Noranda). Each smelter employs a different strategy for slag cleaning, thus each smelter obtains different results. This article outlines and compares the different slag-cleaning systems that are currently in operation in the Chilean smelters, their strategies, the equipment in use, and their experiences.

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Optical emission spectroscopy was used to study the glow discharge of CO2 in the pressure range of 0.2 to 1.2 mTorr, power of 160 W and a flux of 35 psi. The emission bands and lines were measured using a monochromator in the wavelength range of 200 to 900 nm. The species observed were C2 (A3Πg – X'3Πu) at 435.7nm and (C'1Πg – b1Πu) at 369.2 nm; O2 (b1Σg+ ‐ X3Σg–) at 628.2; CO (a'3Σ ‐ a3Π) at 674.7 nm; O2+ (A2Πu ‐ X2Πg) at 339.3 and 289.2 nm; CO2+ (A2Π ‐ X2Π) at 353.2 nm; CO2 (1B2 – X1Σ+) at 391.7 nm; CO+ (A2Π – X2Σ) at 577.7 nm; and O3 (1B2 – X1A1) at 327.2 nm. We observed that the emission intensities bands have an almost constant behavior as function of the pressure in the range of 0.2 to 0.6 mTorr, followed by an increasing behavior. The electron temperature and ion density were determined by a double Langmuir probe. The electron temperature was found of 8.53 eV, and the electron concentration of 7.11 x 109 cm–3 at a pressure of 0.8 mTorr. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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This work characterizes the degradation of the textile dye azo Acid Black 52 by measuring several physical and chemical parameters. A corona plasma was created at atmospheric pressure and applied on the liquid-air interface of water samples containing the dye. 1.0 mM of ferrous sulfate (FeSO4) was added to 1.0 mM dye solution, for a total volume of 250 mL. For each treatment, a number of parameters were quantified. These were voltage, current, temperature, loss of volume, pH, electrical conductivity, concentration, optical mission spectra, chemical oxygen demand (COD), total organic carbon (TOC), and the removal ratio. Because of the increase in the sample temperature, the volume lost by evaporation was explored. The results show that the efficiency of the dye degradation by plasma is a function of treatment time. Moreover, the reactive concentration of FeSO4 and the exposition time of the plasma were varied at a constant volume, leading to the determination of the concentrations and optimal times. Considering the degradation and removal parameters, at the maximum treated time of 80 min, it found that COD was of 96.36%, TOC of 93.93%, and the removal ratio of 97.47%.

ResumenEste artículo tiene como propósito general presentar y discutir algunos de los elementos que interrelacionados, permiten aproximarse al fenómeno del trabajo infantil. Así, no se busca exponer un panorama cuantitativo de la situación de niñas, niños y adolescentes (NNA) que trabajan, sino exhibir un marco referencial que proporcione posibles perspectivas para su abordaje, análisis e interpretación. Para lograr lo anterior se recurre a la presentación del marco jurídico, tanto internacional como en el contexto mexicano. Además, se presentan algunos datos que permiten ejemplificar la situación de NNA que trabajan. Como forma de justificar la importancia de este trabajo se debe mencionar que en México no existe un diagnóstico integral e interdisciplinario del trabajo infantil, por lo que se hace necesario profundizar en el tema por medio del diálogo entre distintas disciplinas, visiones y aproximaciones a un fenómeno de naturaleza extremadamente compleja, y que muchas veces se encuentra invisibilizado. Palabras clave: Trabajo infantil, Conceptualización jurídica, Derechos de niñas, niños y adolescentes, México. PARTICULARITIES AND COMPLEXITIES OF CHILD LABOR: CONCEPTUAL ASPECTS AND EMPIRICAL APPROACH TO A HIDDEN PHENOMENON WITH DIFFERENT DIMENSIONS AbstractThis article aims to presents and discuss some elements interrelated that allow approaching to child labor phenomenon. Thus, it does not seek to expose a quantitative overview of children (boys and girls), and adolescents situation (NNA for its acronym in Spanish), but to display framework that provides possible prospects for their approach, analysis and interpretation.