Towards Zero CO2 Continuous Steelmaking Directly from Ore

Abstract

In-line continuous processing of high-grade hematite ore (crushed ore or fines) with a pure hydrogen reductant is assessed. An appraisal is made of the rate controlling mechanisms involved in the reduction of a pure layer of molten wustite being transported by floating on a molten carrier iron carbon-free medium at temperatures just in excess of the iron melting point. Published research clearly indicates that under these conditions the kinetics are principally controlled by molecular gaseous diffusion. Thus, the rate is essentially not influenced by total gas pressure above 1 atmosphere. Accordingly, on safety grounds it is recommended that high pressure should not be used for hydrogen steelmaking in the future, but the operation should be conducted close to atmospheric pressure with low pressure steam encapsulation of the plant items involved. Using hydrogen as the reductant means that sub-surface nucleation of CO bubbles cannot disrupt continuous processing. The operation is then no different to processing a normal liquid phase. The off-gases from the reduction zone of a melt circulation loop are superclean and only contaminated with iron vapor. Accordingly, the best available technology becomes available for energy conservation without risk of non-fusible solids deposition. The net result is that the energy requirements are expected to be superior to other potential processes.

Reduction Behavior and Kinetics of Iron Ore Pellets under H₂–N₂ Atmosphere

“…Ming-Hua BAI, 1) Hu LONG, 1) * Su-Bo REN, 1) Dong LIU 2) and Chang-Fu ZHAO Direct reduction behavior and dynamic characteristics of oxidized pellets under the 75%H 2 -25%N 2 atmosphere at 760, 900, 1 000°C are studied in this paper. 500 g oxidized pellets in the size of 10-12.5 mm are reduced by gas with the flow rate of 12 L·min − 1 for 1 hour.…”

“…[1][2][3][4] The iron and steel production is responsible for the vast majority of industrial greenhouse gases emissions. 5,6) Hence, it is urgent to develop breakthrough technologies for emissions reduction.…”

The Materials Science behind Sustainable Metals and Alloys

“…), carbon-free reductants (in the form of solids, molecules (H 2 , NH 3 , etc. ), ions, protons, electrons), while Figure shows several types of reduction reactors and downstream processing pathways, including also several processing variants for sustainable steel making. ,,,− The most important ones are the blast furnace where coke-based CO reduces iron ores to a near-eutectic Fe-C alloy; the shaft furnace for direct reduction, in which solid-state cm-sized ores or pellets are in static piles exposed to a gaseous reductant; fluidized bed or rotary furnaces where fines of sub-mm-sized ore particles are as dynamic agglomerates (particles in motion) exposed to a gaseous reductant; and the electric arc furnace, which is a standard industry furnace with an electric arc ignited between electrodes and solids (today usually scrap) or liquids. The electric arc can turn the gas atmosphere inside the furnace into a plasma.…”

“…A variety of carbon-free or carbon-reduced molecular carriers and their mixtures can be used in metallurgical reduction and heating processes. , The most promising are sustainably produced (green) hydrogen, ammonia, methanol, and methane, as well as mixtures of these media, with the required partial pressures and temperatures derived from the underlying thermodynamic equilibria as shown in Figure –Figure . Their use as a substitute for coke in metallurgical reduction is especially promising.…”

Review and data evaluation for high-temperature reduction of iron oxide particles in suspension

“…While there are many studies on the reduction from wüstite to iron [31][32][33][34][35][36][37][38] and reduction of iron oxides from 673 to 1473 K, this work focusses on the suspension reduction process of haematite and magnetite above 1473 K for emerging alternative ironmaking processes. A reaction kinetics study is a basis for a study of the whole reaction process.…”