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Panindícuaro de la Reforma, Mexico

Chaidez-Felix J.,IPN ESIQIE | Romero-Serrano A.,IPN ESIQIE | Hernandez-Ramirez A.,IPN ESIQIE | Perez-Labra M.,Academic Area of Earth Science and Materials | And 3 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

An experimental study was carried out to estimate the effect of the lead impurities on the silver distribution in the phases formed in the lead blast furnace. Samples of sinter with different contents of Cu, S, As and Sb were equilibrated under reducing atmosphere (p(CO)/p(CO2)=2.45) at 1573 K in a tube furnace and slowly cooled. The samples were characterized by scanning electron microscopy and microanalysis (SEM-EDS). There were five immiscible phases: slag (CaO, FeO and SiO2), matte (S, Cu and Fe), speiss (As, Fe and Cu), Cu-Sb phase and lead bullion (Pb, Ag, Sb, Cu, etc). The results showed that Cu and Sb promote silver losses during the process since they form a liquid solution with higher silver solubility than liquid bullion. Sulfur and arsenic react with copper to form the matte and speiss phases, respectively. The effect of S and As is to reduce the amount of Cu-Sb alloy and then the silver losses from the bullion. © 2014 The Nonferrous Metals Society of China.

Perez-Labra M.,Academic Area of Earth Science and Materials | Romero-Serrano A.,ESIQIE IPN | Salinas-Rodriguez E.,Academic Area of Earth Science and Materials | Avila-Davila E.O.,Pachuca Institute of Technology | Reyes-Perez M.,Academic Area of Earth Science and Materials
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2012

Rubidium jarosite was synthesized as a single phase by precipitation from aqueous solution. X-ray diffraction and scanning electron microscopy energy-dispersive spectrometry analysis showed that the synthetic product is a solid rubidium jarosite phase formed in spherical particles with an average particle size of about 35 μm. The chemical analysis showed an approximate formula of Rb 0.9432Fe 3(SO 4) 2.1245(OH) 6. The decomposition of jarosite in terms of solution pH was thermodynamically modeled using FACTSage by constructing the potential pH diagram at 298 K (25 °C). The E-pH diagram showed that the decomposition of jarosite leads to a goethite compound (FeO•OH) together with Rb + and $$ {\text{SO}}-{4}^{2 - } $$ ions. The experimental Rb-jarosite decomposition was carried out in alkaline solutions with five different Ca(OH) 2 concentrations. The decomposition process showed a so-called "induction period" followed by a progressive conversion period where Rb + and $$ {\text{SO}}-{4}^{2 - } $$ ions formed in the aqueous solutions, whereas calcium was incorporated in the solid residue and iron gave way to goethite. The kinetic analysis showed that this process can be represented by the shrinking core chemically controlled model with a reaction order with respect to Ca(OH) 2 equals 0.4342 and the calculated activation energy is 98.70 kJ mol -1. © 2012 THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL.

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