Reduction and Dissolution Behaviour of Manganese Slag in the Ferromanganese Process

Xiang Li,Merete Tangstad,Kai Tang

doi:10.3390/min10020097

Xiang Li, Merete Tangstad + Show 1 more

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https://doi.org/10.3390/min10020097

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Abstract

The reduction and liquidus behaviour of manganese slag with different basicities were studied in non-isothermal experiments in the temperature range of 1400–1500 °C. Certain amounts of quartz were added to Assmang ore (South Africa), and lime was added to Comilog ore (Gabon), to adjust the charge basicity to 0.5, 0.8 and 1.2. The extent of manganese ore reduction as a function temperature were determined by thermo-gravimetric (TG) balance. Morphology of ores and its change in the course of reduction was examined by scanning electron microscopy (SEM). The results show that the reduction rate of Assmang slag decreases with decreasing basicity, as the liquidus temperature of slag decreases. When spherical MnO phase is present, the activity of MnO is high, and the reduction rate is rapid. Comilog slags show a much higher reduction rate than Assmang slags. The activation energies of MnO reduction between 1400 to 1500 °C are estimated in this study and found to be 230 kJ/mol for Assmang charges and 470 kJ/mol for Comilog charges. The dissolution behaviours of Assmang and Comilog slags were also studied by FactSage simulation and verified by experiments.

Highlights

Ferromanganese (FeMn) alloys are essential to iron and steel making because of its sulfur fixing, deoxidizing and alloying properties as well as its low cost
The change of Assmang charge basicity by addition of quartz does not show a visible effect on pre-reduction rate, as expected
The reduction and liquidus behaviour of Assmang and Comilog slags with different basicities are studied in the FeMn process, with a continuous temperature increase under CO atmospheric of the the slag at liquidus calculated liquiduswith relations for pressure

Summary

Introduction

Ferromanganese (FeMn) alloys are essential to iron and steel making because of its sulfur fixing, deoxidizing and alloying properties as well as its low cost. FeMn is commercially produced by carbothermal reduction of manganese ores, primarily in electric submerged arc furnaces (SAF) [1,2]. The ore feed containing higher manganese oxides (MnO2 , Mn2 O3 and Mn3 O4 ) first enters the pre-reduction zone in SAF where water evaporates. The pre-reduction zone involves numerous reactions, as described by following reactions.

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