Kinetics of Hydrogen Reduction of Magnetite Concentrate Particles in Solid State Relevant to Flash Ironmaking

Abstract

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.

Reduction Kinetics of Hematite Powder in Hydrogen Atmosphere at Moderate Temperatures

“…The size of the crucible is φ6.6 mm × h5.8 mm (inner diameter × inner height) and the thickness of the alumina crucible is 0.5 mm. Normally, kinetic studies use a large excess amount of reducing gas in the experiments [10,17]. Pure hydrogen with a flow rate of 50 mL/min STP was used as the reactant gas during the reaction.…”

“…Numerous studies have reported the reduction kinetics of iron ore by H 2 or H 2 -containing mixtures [3][4][5]10,[13][14][15][16][17][18][19][20][21]. The experimental research of Pineau et al [18] indicates that the reduction path of hematite is as follows:…”

“…Sohn et al [6][7][8] has proposed a flash reduction process which uses H 2 to reduce magnetite concentrates. With continuing studies, the feasibility of this process is more and more clear [9][10][11]. Recently, a direction reduction technology, named HYBRIT, was created by SSAB, LKAB and Vattenfall in Sweden, aiming to replace coking coal with hydrogen in the process [12].…”

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

“…Therefore, the reduction kinetics were investigated in the temperature range 1150-1600 • C using H 2 , CO, or H 2 + CO as the reducing gas by Sohn and coworkers [36][37][38][39][40][41][42]. Reduction by H 2 + CO is complicated because of the simultaneous reduction by the two gases as well as the water-gas shift reaction involving CO and H 2 with the product gases H 2 O and CO 2 .…”

Numerical Analysis of Effect of Water Gas Shift Reaction on Flash Reduction Behavior of Hematite with Syngas

“…The drop tube reactor has been adopted as an ideal laboratory reactor for flash reduction of iron ore particles because of the advantages of fast heating rate, concurrent gas-solids flow without back mixing and particle collision, and short resident time. [3][4][5][6][7][8][9][10][11][12] The chemical reactions in the flash reduction process involves heterogeneous reactions between particles and gas, as well as homogeneous reactions among gas. The interaction between particles in the reactor is neglected due to the low volume fraction of particles.…”