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

Reduction of Iron Oxides with Hydrogen—A Review

Kinetics and mechanisms of direct reduction of iron ore-biomass composite pellets with hydrogen gas

This paper provides a critical review on the current status and potential of biomass utilization in ferrous metallurgical processes, i.e., the blast furnace (BF) – basic oxygen furnace (BOF) route, the direct reduction (DR) – electric arc furnace (EAF) route, the scrap – EAF route and the other routes. In the BF-BOF route, biomass can be used as a fuel for iron ore sintering, or as a raw material for the production of bio-coke, and utilized for blast furnace injection. In the DR-EAF route, direct reduction iron can be produced form iron ore and biomass pellet. In the scrap – EAF route, biomass can be utilized in EAF through a cogeneration system. In addition, biomass can be utilized in magnetic separation of refractory low-grade iron ore, in reuse of iron and steel slag, or as an adsorbent for pollutant control, etc. The challenges and outlook of biomass utilization in metallurgical industry are also discussed in this paper.

Current status and potential of biomass utilization in ferrous metallurgical industry

A new route for making steel from iron ore based on the use of hydrogen to reduce iron oxides is presented, detailed and analyzed. The main advantage of this steelmaking route is the dramatic reduction (90% off) in CO2 emissions compared to those of the current standard blast-furnace route. The first process of the route is the production of hydrogen by water electrolysis using CO2-lean electricity. The challenge is to achieve massive production of H2 in acceptable economic conditions. The second process is the direct reduction of iron ore in a shaft furnace operated with hydrogen only. The third process is the melting of the carbon-free direct reduced iron in an electric arc furnace to produce steel. From mathematical modeling of the direct reduction furnace, we show that complete metallization can be achieved in a reactor smaller than the current shaft furnaces that use syngas made from natural gas. The reduction processes at the scale of the ore pellets are described and modeled using a specific structural kinetic pellet model. Finally, the differences between the reduction by hydrogen and by carbon monoxide are discussed, from the grain scale to the reactor scale. Regarding the kinetics, reduction with hydrogen is definitely faster. Several research and development and innovation projects have very recently been launched that should confirm the viability and performance of this breakthrough and environmentally friendly ironmaking process.

Hydrogen Ironmaking: How It Works

Hydrogen production from steam reforming of coke oven gas and its utility for indirect reduction of iron oxides in blast furnace

The kinetics of the reduction of hematite pellets using hydrogen-carbon monoxide mixtures as reducing agent was described by using the "grain model". This model involves the particle size and the porosity of the pellet asmain structural parameters which affect directly the kinetics of the hematite pellets during the reduction process. The predictions of the model were compared with the experimental results. Fired hematite pellets were reduced at 850°C using hydrogen, carbon monoxide and Midrex gas. The weight loss technique was used to follow the reduction process. The reduction of iron oxide pellets using hydrogen or carbon monoxide is a mixed controlled system, where chemical reaction and internal gas diffusion are competing processes during the first stage of the reduction, while internal gas diffusion becomes controlling step at the last stage of the process. The reduction of iron oxide pellets using Midrex gas is a mixed controlled system throughout the whole reduction process.

Kinetic analysis of the iron oxide reduction using hydrogen-carbon monoxide mixtures as reducing agent

The rate of dissolution of sponge iron into molten steel has been studied. Reduced pellets from Midrex and HyL processes and pellets containing coal char were used. The dissolution of the pellets is accompanied by continuous gas evolution which is due mainly to the reduction of iron oxides remaining in the pellets by the carbon within the system. It was found that HyL pellets dissolved faster than Midrex and Midrex pellets dissolved faster than Sartenejas. The rate of heat transfer from the bath to the pellet was found to increase with increasing gas evolution. The melting process was simulated by a mathematical model by assuming heat transfer control. This model allowed the calculation of the heat transfer coefficient as a function of the instantaneous radius of the pellet.

The rate of dissolution of pre-reduced iron in molten steel.

In this article a new design for a thermal plasma reactor with expansion chamber for aluminum nitride (AlN) synthesis is proposed. The new reactor was constructed of stainless steel (AISI 304), and this was proved with a high temperature direct nitriding process of aluminum chloride and with a thermal carbonitriding process of gibbsite. The product obtained in the direct nitriding runs, was AlN with approximately 90% purity; while the AlN obtained in the carbonitriding test was mixed with other minor products, such as corundum and aluminum oxynitride. A reaction mechanism is proposed to explain the decomposition of the solid precursor and nucleation of the AlN.

Diseño y evaluación de un reactor de plasma térmico para síntesis de Nitruro de aluminio

A process is disclosed for recovering nickel and magnesium from natural material by extracting them in the presence of a spent sulfur containing iron based hydroconversion catalyst, under oxidative conditions.

Miltón Manrique

Papers

Kinetic analysis of the iron oxide reduction using hydrogen-carbon monoxide mixtures as reducing agent

The rate of dissolution of pre-reduced iron in molten steel.

Diseño y evaluación de un reactor de plasma térmico para síntesis de Nitruro de aluminio

Process for recovery of nickel and magnesium from a naturally occurring material