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Hong Yong Sohn

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Papers by Hong Yong Sohn

Novel Flash Ironmaking Technology

Despite the dominance of the blast furnace ironmaking process, increasing attention is paid to th... more Despite the dominance of the blast furnace ironmaking process, increasing attention is paid to the development of a new technology with lower energy consumption and CO 2 emissions. An ideal process would also use widely available iron ore concentrate. It should also require much less capital investment than the blast furnace/coke oven combination. At the University of Utah, we are working on a drastically novel process for an alternative technology to meet these demands. In response to increasing concerns about energy consumption and atmospheric emissions from the conventional and other emerging ironmaking plants, especially carbon dioxide, we are developing the Flash Ironmaking Process. This novel technology eliminates the highly problematic cokemaking and pelletization/sintering steps by directly utilizing iron ore concentrates, which are in abundance in the United States and elsewhere. In this paper, some recent advances on this work are discussed.

FEATURED REVIEW †To whom correspondence should be addressed. Chemical Reaction Engineering in the Chemical Processing of Metals and Inorganic Materials Part II. Chemical Process Modeling and Simulation

Abstract−In traditional chemical reaction engineering, it is possible to incorporate only the sim... more Abstract−In traditional chemical reaction engineering, it is possible to incorporate only the simplified aspects of fluid flow, mixing, and mass/heat transfer into the analysis of chemical reaction rates and reactor design. As a con-sequence of the advent of high-speed, high-capacity computing capacity, complex processes involving chemical reactions have become amenable to analysis and modeling. This has also resulted in the merging of various disciplines of chemical engineering in formulating detailed descriptions of complex processes. Developments that exemplify this trend over the years are discussed in this review. Several examples from the author’s previous work are used to illustrate the application of chemical reaction engineering principles to the modeling and analysis of complex systems involving the chemical processing of metals and other inorganic materials.

Design of Novel Flash Ironmaking Reactors for Greatly Reduced Energy Consumption and CO2 Emissions

Metals, 2021

The development of a novel ironmaking technology based on fine iron ore concentrate in a flash re... more The development of a novel ironmaking technology based on fine iron ore concentrate in a flash reactor is summarized. The design of potential industrial reactors for flash ironmaking based on the computational fluid dynamics technique is described. Overall, this simulation work has shown that the size of the reactor used in the novel flash ironmaking technology (FIT) can be quite reasonable vis-à-vis the blast furnaces. A flash reactor of 12 m diameter and 35 m height with a single burner operating at atmospheric pressure would produce 1.0 million tons of iron per year. The height can be further reduced by either using multiple burners, preheating the feed gas, or both. The computational fluid dynamics (CFD)-based design of potential industrial reactors for flash ironmaking pointed to a number of features that should be incorporated. The flow field should be designed in such a way that a larger portion of the reactor is used for the reduction reaction but at the same time excessive ...

Plasma Synthesis of Advanced Metal Oxide Nanoparticles and Their Applications as Transparent Conducting Oxide Thin Films

Molecules, 2021

This article reviews and summarizes work recently performed in this laboratory on the synthesis o... more This article reviews and summarizes work recently performed in this laboratory on the synthesis of advanced transparent conducting oxide nanopowders by the use of plasma. The nanopowders thus synthesized include indium tin oxide (ITO), zinc oxide (ZnO) and tin-doped zinc oxide (TZO), aluminum-doped zinc oxide (AZO), and indium-doped zinc oxide (IZO). These oxides have excellent transparent conducting properties, among other useful characteristics. ZnO and TZO also has photocatalytic properties. The synthesis of these materials started with the selection of the suitable precursors, which were injected into a non-transferred thermal plasma and vaporized followed by vapor-phase reactions to form nanosized oxide particles. The products were analyzed by the use of various advanced instrumental analysis techniques, and their useful properties were tested by different appropriate methods. The thermal plasma process showed a considerable potential as an efficient technique for synthesizing ...

Development of the Flash Ironmaking Technology (FIT) for Green Ironmaking with Low Energy Consumption

Journal of Energy and Power Technology, 2021

This article describes the development of a novel ironmaking technology based on flash reduction.... more This article describes the development of a novel ironmaking technology based on flash reduction. The development started with the proof of the kinetic feasibility, considering that a typical flash reactor provides only a few seconds of residence time. This was followed by tests in a laboratory flash reactor and finally a pilot plant operation. The rate equations formulated in this work were developed considering the optimum combination of temperature, residence time, and reducing gas partial pressure to achieve > 95% reduction degree. Experiments in the intermediate-scale laboratory flash reactor indicated that more than 90% reduction degree could be obtained in a few second residence time at temperature as low as 1175 °C. A pilot reactor operating at 1200–1550 °C was installed and run to collect data necessary for scaling up the process. The tests in this large reactor validated the design concept in terms of heat supply and residence time, and identified technical hurdles. Thi...

Development of a Flash Ironmaking Technology Based on Hydrogen or Natural Gas - Implications on Energy and Greenhouse Gas Emissions

Proceedings of the 3rd World Congress on Mechanical, Chemical, and Material Engineering, Jun 1, 2017

Novel Nanocrystalline Intermetallic Coatings for Metal Alloys in Coal-fired Environments

Energy Consumption and CO2 Emissions in Ironmaking and Development of a Novel Flash Technology

Metals, 2019

The issues of energy consumption and CO2 emissions of major ironmaking processes, including sever... more The issues of energy consumption and CO2 emissions of major ironmaking processes, including several new technologies, are assessed. These two issues are interconnected in that the production and use of fuels to generate energy add to the total amount of CO2 emissions and the efforts to sequester or convert CO2 require energy. The amounts of emissions and energy consumption in alternate ironmaking processes are compared with those for the blast furnace, currently the dominant ironmaking process. Although more than 90% of iron production is currently through the blast furnace, intense efforts are devoted to developing alternative technologies. Recent developments in alternate ironmaking processes, which are largely driven by the needs to decrease CO2 emissions and energy consumption, are discussed in this article. This discussion will include the description of the recently developed novel flash ironmaking technology. This technology bypasses the cokemaking and pelletization/sintering...

Model for the fragmentation of copper matte particles during flash converting

Mining, Metallurgy & Exploration, 2008

A mathematical model to represent the expansion and fragmentation of copper matte particles oxidi... more A mathematical model to represent the expansion and fragmentation of copper matte particles oxidized under flash converting conditions is presented. The model assumes that the particles are initially nonporous, have a constant mass prior to fragmentation and travel at a constant velocity throughout the reaction chamber. The model requires the specification of the following five parameters: the particle expansion rate, a fragmentation diameter factor, a fragmentation size distribution parameter and the fractions of the finest and the coarsest particles in the feed that undergo fragmentation. The model predictions show good agreement with the experimental data collected in a laboratory furnace over a wide range of experimental conditions. The evolution of the size distribution of the particles along the reactor length was computed, and the model parameters were correlated with the experimental operating variables. Model predictions indicate that particle residence time is an important factor in the generation of dust. The presence of two maxima in the particle density function may be attributed to turbulent conditions prevailing in the furnace, which cause particles to follow different trajectories within the furnace even if they are injected at the same location.

Rate Enhancement of the Gaseous Reduction of Iron Oxide Pellets by Pressure Cycling

Transactions of the Iron and Steel Institute of Japan, 1984

The e ffect of carrying out gaseous reduction of iron oxide under external pressure cycling has b... more The e ffect of carrying out gaseous reduction of iron oxide under external pressure cycling has been investigated. When the reduction is carried out at 800 °C with pellets of 30 O porosity, relatively moderate pressure cycling with an amplitude of 0.5 atm and frequency of 0.5 cps can lead to about 25 % higher reduction within 20 min from the start of reaction. A threefold improvement in initial conversion rate can be obtained if higher amplitude and frequency of cycling are used. Computation shows that, for pellets and naturally occurring hematite ore, viscous flow effects can be neglected. The results of the investigation provide justification for further research in the use of external pressure cycling to overcome di, fusional resistances in gas-solid reaction systems.

Retraction： Gaseous Pre-reduction for the Magnetic Beneficiation of Ferruginous Low-grade Mn Ore

ISIJ International, 2012

Because of intensive mining of high-grade manganese ores for a long time while leaving behind the... more Because of intensive mining of high-grade manganese ores for a long time while leaving behind the low-grade ores, the utilization of the latter has become necessary. In this study, ferruginous low-grade manganese ore was selectively reduced by CO, which converted iron oxide to Fe3O4 while manganese oxide was reduced to MnO. The iron-rich component was then separated by magnetic separation. The effects of sample particle size and various reduction parameters on the efficiency of magnetic separation were studied. Under the optimum experimental conditions, the manganese content in the ore increased from around 36% to more than 44%, and almost 50% of iron was removed at a Mn loss of around 5%.

Alumina from coal wastes through the formation of aluminum nitride by carbothermal reduction under nitrogen

Industrial & Engineering Chemistry Product Research and Development, 1986

... Bureau of Mines (Bengtson, 1979 ... Thermodynamic Considerations When carried out at atmosphe... more

Suspension Hydrogen Reduction of Iron Oxide Concentrates

Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

This report contains detailed information of the research program entitled "Development of B... more This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

Reaction Mechanisms in the Li3AlH6/LiBH4 and Al/LiBH4 Systems for Reversible Hydrogen Storage. Part 2: Solid-State NMR Studies

The Journal of Physical Chemistry C, 2011

The carbothermal reduction of nickel sulfide in the presence of lime

Metallurgical Transactions B, 1983

The chemical feasibility of reducing nickel sulfide with carbon and lime, without emitting sulfur... more The chemical feasibility of reducing nickel sulfide with carbon and lime, without emitting sulfurcontaining gases, has been investigated. A reaction mixture of nickel sulfide particles intimately mixed with carbon and lime (used as a sulfur scavenger) was prepared. The thermodynamics of reacting this mixture in an inert atmosphere, producing carbon dioxide and carbon monoxide, was examined and found favorable. The rate of this reaction was measured in the temperature range 800 to 1124 ~ (1073 to 1397 K). The effects of particle size and relative amounts of solid reactants were determined. The possibility of recovering the product nickel by carbonylation was also investigated.

A mathematical model for the solution mining of primary copper ore: Part I. leaching by oxygen-saturated solution containing no gas bubbles

Metallurgical Transactions B, 1983

An unsteady-state, one-dimensional model which simulates the solution mining of a rubblized coppe... more An unsteady-state, one-dimensional model which simulates the solution mining of a rubblized copper ore body deeply buried below the water table has been developed. Leaching is accomplished by pumping water saturated with oxygen into the bottom of the flooded rubble chimney. The physical processes incorporated in the present model include the axial convective transport of mass and heat, axial dispersion of mass, mass transfer between the bulk fluid and solid surface, and pore diffusion within the ore fragments. The solution withdrawn from the top of the chimney is recycled through the bottom of the chimney, and the temperature of the chimney is allowed to build up by means of the heat generated during leaching. The coupled model equations are solved numerically by an implicit finite-difference method. Model calculations for the leaching process are made for two different modes of operation: (1) constant flow-rate and (2) variable flow-rate of the leach solution during leaching. The calculated results from both modes of operation indicate that the fractional recovery of copper increases with decreasing ore particle size, ore grade, pyrite/chalcopyrite molar ratio, and shape factor. Copper recovery is rather insensitive to the chimney porosity under typical operating conditions.

Re-oxidation Kinetics of Flash-Reduced Iron Particles in H2-H2O(g) Atmosphere Relevant to a Novel Flash Ironmaking Process

Metallurgical and Materials Transactions B, 2013

ABSTRACT A novel flash ironmaking process based on hydrogen-containing reduction gases is under d... more ABSTRACT A novel flash ironmaking process based on hydrogen-containing reduction gases is under development at the University of Utah. The goal of this work was to study the possibility of the re-oxidation of iron particles in a H2-H2O gas mixture in the lower part of the flash reactor from the kinetic point of view. The last stage of hydrogen reduction of iron oxide, i.e., the reduction of wustite, is limited by equilibrium. As the reaction mixture cools down, the re-oxidation of iron could take place because of the decreasing equilibrium constant and the high reactivity of the freshly reduced fine iron particles. The effects of temperature and H2O partial pressure on the re-oxidation rate were examined in the temperature range of 823 K to 973 K (550 °C to 700 °C) and H2O contents of 40 to 100 pct. The nucleation and growth kinetics model was shown to best describe the re-oxidation kinetics. The partial pressure dependence with respect to water vapor was determined to be of first order, and the activation energy of re-oxidation reaction was 146 kJ/mol. A complete rate equation that adequately represents the experimental data was developed.

Interphase mass transfer with bulk flow normal to the phase boundary

Korean Journal of Chemical Engineering, 2004

The effect of bulk flow normal to the interface on the interphase mass transfer rate is analyzed ... more The effect of bulk flow normal to the interface on the interphase mass transfer rate is analyzed by using a convective mass transfer coefficient, and a method of deriving the correct choice of the reference mole fraction in the bulk flow term is developed. The effect of the bulk flow and the definition of the proper reference mole fraction have been derived based on diffusion in a binary gas mixture across the boundary layer and expanded to the system of an interfacial gas-solid reaction. The results show that the bulk flow effect together with the proper choice of the reference mole fraction in the bulk flow term is important in obtaining an accurate expression of interphase mass transfer rate. In an extreme situation, the bulk flow effect can cause mass transfer to occur in the direction of increasing concentration. The theoretical development is applied to the rate analysis of the hydrogen reduction of silica.

Effects of Firing and Reduction Conditions on Swelling and Iron Whisker Formation during the Reduction of Iron Oxide Compact

ISIJ International, 2011

The effects of firing and reduction conditions on swelling and iron whisker growth were investiga... more The effects of firing and reduction conditions on swelling and iron whisker growth were investigated. The iron oxide compacts sintered in air were reduced in the tubular high temperature reactor by carbon monoxide or hydrogen. The experimental results showed that catastrophic swelling was suppresed by increasing the firing temperature or the firing time at moderate firing temperatures. The severest swelling happened in the reduction temperature of 900-1 000°C with carbon monoxide. No catastrophic swelling was observed when hydrogen was used as the reducing gas. The SEM micrographs showed that catastrophic swelling was caused by a large amount of long whiskers formed during the reduction. The number of nucleation sites of whisker growth was limited when the firing temperature was increased above 1 000°C, which also suppressed catastrophic swelling. On the basis of exprimental data and SEM results, a conceptual diagram was formulated to describe the effects of firing and reduction conditions on iron whisker growth and swelling.