Iron ore reduction in a continuously operated multistage lab-scale fluidized bed reactor—Mathematical modeling and experimental results

Abstract

Industrial-scale fluidized bed processes for iron ore reduction (e.g., FIOR and FINMET) are operated by continuous feeding of ore, while laboratory tests are mostly performed under batchwise operation. The reduction behavior under continuous operation is influenced by both the residence time of the iron ore particles and the reduction kinetics, which is obtained by batch tests. In a mathematical model for such a process, the effect of both phenomena has to be considered. The residence time distribution of iron ore particles in a laboratory fluidized bed reactor was obtained by measuring the response of a step input and described by mathematical models similar to a continuously stirred tank reactor. In the same reactor, reduction tests with continuous feeding of iron ore were performed. Based on batch tests in a fluidized bed reactor, a mathematical model was developed to describe the kinetics of iron ore reduction under fluidized bed conditions. This kinetic model was combined with the fluidized bed reactor model to describe continuous iron ore reduction. In this detailed model, the change of gas composition while rising in the fluidized bed was considered. The degree of reduction and the gas conversion for reactors in series were calculated. The results obtained by the mathematical model were compared with experimental data from the laboratoryscale reactor.

Empirical reduction diagrams for reduction of iron ores with H2and CO gas mixtures considering non-stoichiometries of oxide phases

“…To gain these parameters subjected to temperature and reduction gas compositions, complex experimental investigations are required. 1,2 For optimal selection of test operating conditions, 3 reduction diagrams of the system Fe, Fe 32d O 4 , Fe 12y O, H 2 , H 2 O, CO and CO 2 have to be calculated. The objectives of this work are to describe empirical calculation methods for reduction diagrams and amounts of non-stoichiometries for the iron oxides magnetite and wustite.…”

Simulation Study on Performance of Z-path Moving-fluidized Bed for Gaseous Reduction of Iron Ore Fines

“…[18][19][20][21] Hence, it is assumed that the mass transfer resistance of gases from the bulk to the surface can be neglected. Thurnhofer 18) conducted microscopical analyses of polished sections of reduced iron ore fines and observed that a high amount of pores were spread through the entire fine. The fine is subdivided into small grains (2 to 10 μm) surrounded by the pores.…”

Evaluation of the impact of cluster formation in a direct reduction shaft furnace through numerical simulation

“…In this context, a huge number of models have already been developed trying to represent the DR process. These models range from singleparticle approaches to multiparticle and components models with topochemical and grain models (Venkateswaran and Brimacombe, 1977, Yu and Gillis, 1981, Takenaka and Kimura, 1986, Negri, 1991and 1995, Parisi and Laborde, 2004, Piotrowski et al, 2005, , Pineau et al, 2006, Thurnhofer, 2006, Valipour et al, 2006, Ajbar et al, 2011, Nouri, 2011, Costa et al, 2013, Shams and Moazeni, 2015, Kazemi, 2017, Castro, 2018, Rocha et al, 2019. Since the DR process can be summarized as a counter-current bed composed of solid and gas into a mass and heat transfer, the most acceptable and useful models correspond to numerical models that comprise the multi interaction and multiple phase theory.…”