Kinetics of Hydrogen Reduction of Chalcopyrite Concentrate
| Autor: | Dinabandhu Ghosh, Ritayan Chatterjee |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Thermogravimetric analysis
Hydrogen Chalcopyrite Chemistry Diffusion Metallurgy Metals and Alloys Analytical chemistry chemistry.chemical_element Activation energy Partial pressure Condensed Matter Physics Mechanics of Materials visual_art Mass transfer Materials Chemistry visual_art.visual_art_medium Particle size |
| Zdroj: | Metallurgical and Materials Transactions B. 46:2692-2705 |
| ISSN: | 1543-1916 1073-5615 |
| DOI: | 10.1007/s11663-015-0419-6 |
| Popis: | A Ghatshila chalcopyrite concentrate (average particle size, 50 μm) containing primarily CuFeS2 and SiO2 (Cu 16 pct) was reduced by a stream of hydrogen in a thermogravimetric analyzer (TGA) at selected temperatures [1173 K to 1323 K (900 °C to 1050 °C)], hydrogen flow rates, partial pressures of hydrogen (0.33 × 101.3 to 101.3 kPa), and sample bed heights. The product was a mixture of Cu (26 pct), SiO2, CuFeO2, and Fe. The rate equations for the three typical controlling mechanisms, namely, gas film diffusion (mass transfer), pore diffusion, and interfacial reaction, have been derived for the system geometry under study and applied to identify the rate-controlling steps. The first stage of the reduction, which extended up to the first 13 minutes, was rate controlled by the interfacial reaction. The last stage, which spanned over the last 60 to 120 minutes and accounted for a small percentage of reduction, was controlled by pore diffusion through the built-up Cu (and Fe) layer. The activation energy in the first stage was 101 kJ mol−1 and that in the second stage was 76 kJ mol−1. Subsequent acid leaching with 1 M HCl solution of the reduction product removed all soluble species, leaving a Cu (53.3 pct) + SiO2 mixture, with a small concentration (2.7 pct) of Cu2O in it. This result compares well with the predicted final mixture of Cu (59 pct)-SiO2 based on a mass balance on the starting concentrate. A follow-up heating at 1523 K (1250 °C) produced a sintered Cu-SiO2 composite with spherical copper particles of 400 µm diameter embedded in a silica matrix. Elemental chemical analyses were carried out by energy-dispersive X-ray spectroscopy/atomic absorption spectroscopy. The phase identification and microstructural characterization of Cu-SiO2 mixtures were carried out by X-ray powder diffraction and optical microscopy. |
| Databáze: | OpenAIRE |
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