The crystal structure, physical and chemical properties, preparation methods and applications of titanium suboxides (TinO2n−1, n = integer greater than one) have recently attracted tremendous attention.

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A novel ironmaking process is under development at the University of Utah to produce iron directly from iron oxides concentrates by the gas-solid flash reaction using gaseous fuels and reductants. This process will reduce energy consumption and minimize carbon dioxide emissions. Having investigated the hydrogen reduction kinetics of magnetite and hematite concentrate particles relevant to the novel flash ironmaking process, the carbon monoxide reduction kinetics of hematite concentrate particles (average particle size 21 lm) was determined in the temperature range 1473 K to 1623 K (1200°C to 1350°C) under various carbon monoxide partial pressures. At 1623 K (1350°C) and residence time 5 seconds, the reduction degree of hematite concentrate particles was more than 90 pct under a pure carbon monoxide. This is slower than reduction by hydrogen but still significant, indicating that CO will contribute to the reduction of hematite concentrate in the flash process. The kinetics of CO reduction separately from hydrogen is important for understanding and analyzing the complex kinetics of hematite reduction by the H 2 + CO mixtures. The nucleation and growth rate equation with the Avrami parameter n = 1.0 adequately described the carbon monoxide reduction kinetics of hematite concentrate particles. The reduction rate is of 1st order with respect to the partial pressure of carbon monoxide and the activation energy of the reaction was 231 kJ/mol, indicating strong temperature dependence. The following complete rate equation was developed that can satisfactorily predict the carbon monoxide reduction kinetics of hematite concentrate particles and is suitable for the design of a flash reactor dX dt ¼ 1:91 Â 10 7 Â e À231000 RT Â pCO À pCO 2 K Â ð1 À XÞ; where X is the fraction of oxygen removed from iron oxide, R is 8.314 J/mol K, T is in K, p is in atm, and t is in seconds.

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Despite the dominance of the blast furnace ironmaking process, increasing attention is being paid to the development of new technologies with lower energy consumption and CO 2 emissions. At the University of Utah, a novel flash ironmaking technology to meet these demands is under development. This technology eliminates the highly problematic cokemaking and pelletization/sintering steps by directly utilizing iron ore concentrate, which is currently produced in large quantities in North America and elsewhere. This transformative technology is expected to allow significant energy saving and reduced CO 2 emissions compared with the blast furnace process. It has been demonstrated that iron of more than 95 % metallization can be obtained by reduction with hydrogen or a mixture of carbon monoxide and hydrogen in 2-7 s at temperatures of 1473-1823 K. The development of the technology has gone through the stages of proof-of-concept and small laboratory flash reactor tests. A large prototype bench reactor that has most of the features of an eventual industrial reactor has been commissioned. In this paper, some details of advances made in the development are discussed.

The kinetics of hydrogen reduction of solid magnetite concentrate particles is determined in the temperature range 1150–1350 °C as part of the development of a novel ironmaking process on‐going at University of Utah. A laminar‐flow reactor is used to provide the most uniform conditions to measure as accurately as possible the very rapid kinetics of the reduction reaction. Reduction degrees greater than 90% are achieved in a few seconds of residence time, depending on experimental conditions, which are the typical lengths of time available in a flash reaction process. Different particle size fractions are used in the experiments under various hydrogen partial pressures and residence times. The nucleation and growth model with Avrami parameter n = 1 and first‐order dependence on hydrogen partial pressure describes the reduction kinetics. The kinetics have no particle size effect within the size range and reaction conditions tested. The rate equation obtained from this work is being applied to the analysis of the data obtained from a laboratory flash reactor as well as to the design of industrial‐size flash ironmaking reactor in which hydrogen generated from the partial oxidation of natural gas is the main reducing agent.

This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe 2 O 4-decorated multi-walled carbon nanotubes (NiFe 2 O 4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe 2 O 4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe 2 O 4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe 2 O 4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe 2 O 4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe 2 O 4-CNTs. Changes in the free energy of adsorption (DG°), enthalpy (DH°), entropy (DS°), and the activation energy (E a) were determined. The DH°, DG°and E a values indicated that the adsorption of methyl green onto MWCNTs and NiFe 2 O 4-MWCNTs was physisorption.

As an integral part of a research project which aimed to develop a novel green ironmaking process, an experimental determination of the sulfur distribution ratios, L S , between molten iron and CaO−MgO (saturated) −SiO 2 −Al 2 O 3 −FeO slag was carried out in the temperature range of 1550−1650 °C. Oxygen partial pressure was controlled by H 2 /H 2 O equilibrium in the range of 10 −10 −10 −8 atm. Under these conditions applicable to the proposed process, L S was 34 times smaller than that under the conditions of the blast furnace. Considering the relative amounts of sulfur inputs in the two processes as well as other factors, however, the proposed process is expected to produce iron with a lower sulfur content, which will decrease the need for desulfurization in the steelmaking stage.