Browsing by Author "Figueroa, M"

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    Electrochemistry of chalcopyrite
    (ELSEVIER SCIENCE BV, 1996) Gomez, C; Figueroa, M; Munoz, J; Blazquez, ML; Ballester, A
    The electrochemical response of a massive chalcopyrite electrode at two different temperatures, 25 degrees C and 68 degrees C, were compared, The electrolyte used in the experiments was an acidic medium (0.4 g . l(-1) (NH4)(2)SO4, 0.5 g . l(-1) MgSO4 . 7H(2)O, 0.2 g . l(-1) K2HPO4 at pH = 2) which is suitable for the growth of the microorganisms involved in the bioleaching process, The chosen temperatures were optimum for the growth of the mesophilic (Thiobacillus ferrooxidans) and thermophilic (Sulfolobus) microorganisms. The experimental results at both temperatures were similar and confirmed that, during the anodic dissolution of chalcopyrite, a passive film is formed on the surface which restricts the oxidation reactions in the medium by diffusional control of the film, The different responses at the temperatures tested were due to the differing physical structure of the complex films of the electrochemically formed sulphides, polysulphides and elemental sulphur.
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    Use of quillaja saponins (Quillaja saponaria Molina) to control acid mist in copper electrowinning processes - Part 1. Laboratory scale evaluation
    (ELSEVIER SCIENCE BV, 2005) San Martin, RM; Otero, AF; Figueroa, M; Escobar, V; Cruz, A
    This work describes the use of extracts of the Chilean quillaja tree (Quillaja saponaria Molina) as alternative low cost surfactants for the control of acid mist in copper electrowinning (EW). Quillaja extracts contain triterpenoid saponins, which are natural surfactants traditionally used as foaming agents in food and beverages. Two commercial products with different degrees of purification were tested: QL 1000 (R) (non-refined product, 8.4% saponin content) and Mistop (R) (refined product, 16% saponin content). Laboratory experiments determined the effects of both products on electrolyte surface tension (ST), solvent extraction process (SX), current efficiency (CE) and cathode quality.