Quantum mechanics

Engineering

Metallurgy

Materials science

Chromatography

Mineralogy

Degree (music)

Kinetic energy

Acoustics

Physical chemistry

Waste management

Thermodynamics

Hydrogen

Physics

Nuclear engineering

Organic chemistry

Diffusion

Mathematics

Iron ore

Process engineering

Geometry

Fluidized bed

Analytical Chemistry (journal)

Chemistry

Fluidization

Nucleation

Reduction (mathematics)

Hematite

Activation energy

Metallurgical and Materials Transactions B

The reduction kinetics of hematite iron ore fines to metallic iron by hydrogen using a laboratory fluidized bed reactor were investigated in a temperature range between 873 K and 1073 K, by measuring the weight change of the sample portion during reduction. The fluidization conditions were checked regarding plausibility within the Grace diagram and the measured pressure drop across the material during experiments. The apparent activation energy of the reduction was determined against the degree of reduction and varied along an estimated two-peak curve between 11 and 55 kJ mol −1 . Conventional kinetic analysis for the reduction of FeO to metallic iron, using typical models to describe gas–solid reactions, does not show results with high accuracy. Multistep kinetic analysis, using the Johnson–Mehl–Avrami model, shows that the initial stage of reduction from Fe 2 O 3 to Fe 3 O 4 , and partly to FeO, is controlled by diffusion and chemical reaction, depending on the temperature. Further reduction can be described by a combination of nucleation and chemical reaction, whereby the influence of nucleation increases with an increasing reduction temperature. The results of the kinetical analysis were linked to the shape of the curve from apparent activation energy against the degree of reduction.

Iron Ore Reduction by Hydrogen Using a Laboratory Scale Fluidized Bed Reactor: Kinetic Investigation—Experimental Setup and Method for Determination