https://onlinelibrary.wiley.com/doi/epdf/10.1002/srin.201900108

Reduction of Iron Oxides with Hydrogen—A Review

The production and application of hydrogen in steel industry

Kinetics of NiO reduction by H2 and Ni oxidation at conditions relevant to chemical-looping combustion and reforming

Handbook of Heterogeneous Catalysis, Vol. 1–5.

Controlled fires are beneficial for the generation of heat and power while uncontrolled fires, like fire incidents and wildfires, are detrimental and can cause enormous material damage and human suffering. Transport phenomena such as buoyant flow, momentum, convective heat and mass transfer as well as chemical reactions between combustible species and oxygen from the surrounding air play important turbulent mixing are important to the mechanism of flame heat transfer that govern fire release rates. The mechanisms of ignition, flame spread, steady burning flame extinction and smoke transport all need to be considered in fire modelling. In addition, temperature-dependent properties are important factors for consideration. For uncontrolled fires, the evolution in time is of great concern. This edited book presents the state of the art of modelling and numerical simulation of the important transport phenomena in fires. It describes how computational procedures can be used in analysis and design of fire protection and fire safety. Computational fluid dynamics, turbulence modelling, combustion, soot formation, thermal radiation modelling are demonstrated and applied to pool fires, flame spread, wildfires, fires in buildings and other examples. All of the chapters follow a unified outline and presentation to aid accessibility and the book provides invaluable information for both graduate researchers and R&D engineers in industry and consultancy. (Less)

Transport Phenomena in Fires

Kinetics of hydrogen reduction of magnetite ore fines

Reduction of nickel oxide (NiO) powder and pellet by hydrogen was studied in a thermogravimetric apparatus. The variables studied were temperature (573, 673, 773, 873, 973 K) and hydrogen flow rate (100, 150, 200 cc min−1). With NiO powder 70–80 % reduction and with NiO pellets about 95 % reduction were achieved. With both NiO powder and pellets, the rate of reduction increased with increasing temperature and hydrogen flow rate and the linear nature of the fractional reduction versus time (F vs. t) plot, for the most part of the reduction at all temperatures, supported a rate control by gas film diffusion. The activation energies for the reduction of NiO powder and NiO pellet were found to be 20.14 and 19.21 kJ mol−1, respectively. The SEM images showed that the grain size of nickel (Ni) produced was 1–2 μ, and the XRD analysis established the presence of Ni (and the absence of NiO) in the reduced sample.

Reduction of Nickel Oxide Powder and Pellet by Hydrogen

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.

Kinetics of Hydrogen Reduction of Chalcopyrite Concentrate

The structural and morphological characterizations of a chalcopyrite concentrate, collected from the Indian Copper Complex, Ghatshila, India, were carried out by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The concentrate powder was composed mainly of free chalcopyrite and low quartz in about 3:1 weight ratio. The particle size was about 100 μm. Spectroscopic studies (FTIR, Raman, UV-visible) of the concentrate supported the XRD findings, and also revealed a marginal oxidation of the sulfide phase. The energy band gap of the sulfide was found to be 3.4 eV. Differential thermal analysis and thermogravimetry of the concentrate showed a decomposition of chalcopyrite at 658 K with an activation energy of 208 kJ·mol−1, and two successive structural changes of silica at 848 K and 1145 K.

Structural, microstructural, and thermal characterizations of a chalcopyrite concentrate from the Singhbhum shear zone, India

A Ghatshila chalcopyrite concentrate (average particle size, 50 μm) containing primarily CuFeS2 and SiO2 (Cu 16 pct, Fe 26 pct, S 14 pct, Si 5 pct, and O 33 pct) was reduced by a stream of hydrogen in a horizontal tube furnace at 1323 K (1050 °C), producing a mixture of Cu (26 pct), SiO2, Fe2O3, Fe3O4, Cu2O, and Fe. Subsequent acid leaching with 1 M HCl solution of the reduction product removed all iron oxides and iron, and other impurities too, leaving a Cu (53.3 pct) + SiO2 mixture, with a small percentage 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. Elemental chemical analyses were done by energy-dispersive X-ray spectroscopy, which were crosschecked by atomic absorption spectroscopy in the majority of cases. The phase identification and microstructural characterization of Cu-SiO2 mixtures were done by X-ray diffraction, Fourier transform infrared spectroscopy, Rietveld analysis, scanning electron microscopy, and high-resolution transmission electron microscopy (HRTEM). It was found that Cu-SiO2 composites were formed in the final product, with a copper grain size of 385 nm.

Ritayan Chatterjee

Papers

Kinetics of hydrogen reduction of magnetite ore fines

Reduction of Nickel Oxide Powder and Pellet by Hydrogen

Kinetics of Hydrogen Reduction of Chalcopyrite Concentrate

Structural, microstructural, and thermal characterizations of a chalcopyrite concentrate from the Singhbhum shear zone, India

Characterization of Cu-SiO 2 Composite Synthesized by Hydrogen Reduction of Chalcopyrite Concentrate Followed by Acid Leaching