A Sustainable Process to Produce Manganese and Its Alloys through Hydrogen and Aluminothermic Reduction

Jafar Safarian

doi:10.3390/pr10010027

Abstract

Hydrogen and aluminum were used to produce manganese, aluminum–manganese (AlMn) and ferromanganese (FeMn) alloys through experimental work, and mass and energy balances. Oxide pellets were made from Mn oxide and CaO powder, followed by pre-reduction by hydrogen. The reduced MnO pellets were then smelted and reduced at elevated temperatures through CaO flux and Al reductant addition, yielding metallic Mn. Changing the amount of the added Al for the aluminothermic reduction, with or without iron addition led to the production of Mn metal, AlMn alloy and FeMn alloy. Mass and energy balances were carried out for three scenarios to produce these metal products with feasible material flows. An integrated process with three main steps is introduced; a pre-reduction unit to pre-reduce Mn ore, a smelting-aluminothermic reduction unit to produce metals from the pre-reduced ore, and a gas treatment unit to do heat recovery and hydrogen looping from the pre-reduction process gas. It is shown that the process is sustainable regarding the valorization of industrial waste and the energy consumptions for Mn and its alloys production via this process are lower than current commercial processes. Ferromanganese production by this process will prevent the emission of about 1.5 t CO2/t metal.

Highlights

Manganese is little known to the public but is a very important metal to modern society
The massive production of manganese is via the carbothermic reduction of Mn ores in submerged arc furnace (SAF), which yields Mn ferroalloys such as high-carbon ferromanganese (HCFeMn) and silicomanganese (SiMn) [2]
The collected metal and slag phases were characterized by Scanning Electron Microscope (SEM) equipped by Energy

Summary

Introduction

Manganese is little known to the public but is a very important metal to modern society. It is the fifth most used metal in terms of tonnage, being ranked behind iron, aluminum, copper, and magnesium. About 21.7 and 20.3 million tons of Mn ore being mined in 2019 and 2020, respectively [1]. The massive production of manganese is via the carbothermic reduction of Mn ores in submerged arc furnace (SAF), which yields Mn ferroalloys such as high-carbon ferromanganese (HCFeMn) and silicomanganese (SiMn) [2]. About 3.7 Mt of HCFeMn, and about 16 Mt of SiMn were produced in 2020, respectively. Manganese metal production was about 1.4 Mt in 2020

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Discussion

Conclusion