A Dynamic Model of a Submerged
Plasma Slag Fuming Process
Samant Nagraj, Mathias Chintinne, Muxing Guo and Bart Blanpain
Abstract Submerged plasma slag fuming technology is a process intensification
of the traditional (coal-fired) slag fuming technology. A general dynamic model of
the plasma-driven slag fuming process has been developed in FactSage 7.0 based
on Metallo Belgium’s industrial scale submerged plasma slag fuming furnace. This
model describes the chemical reactions, phase equilibria and heat transfer in each
sub-unit operation, and the heat and mass transfer between the subsequent subunit operations of the slag fuming process. The model was validated on several
process batches. Upon assessing the simulation results, a deviation was found from
the industrial process, which can be explained using kinetic factors.
Keywords Metal extraction · Metal recycling · ZnO · FactSage
Introduction
Slag fuming is a reduction process to recover Zn from zinc-rich metallurgical residues
such as lead blast furnace slag, secondary copper smelter slag, and electric arc furnace
dust. The process involves three steps: (1) heating the slag over Zn vaporization
temperature, (2) reducing the ZnO in the slag by a reducing agent and evaporating
the Zn from the molten slag bath, and (3) cooling the Zn vapours to collect metallic Zn
condensate or oxidizing the Zn vapour with air to produce ZnO precipitates. Several
technologies have been developed over the years based on this principle, such as the
Waelz-kiln process, the Enviroplas process, and the QSL process [1–3].
In a conventional fuming process, the heating of the slag bath is generally done by
injecting product gases of combusted fossil fuel (typically, coal and natural gas) into
the reactor through side submerged tuyeres or a top submerged lance. The product
S. Nagraj (B) · M. Chintinne
Metallo Belgium N.V., Nieuwe Dreef 33, 2340 Beerse, Belgium
e-mail: samant.nagraj@metallo.com
S. Nagraj · M. Guo · B. Blanpain
Department of Materials Engineering (MTM), KU Leuven, Kasteelpark Arenberg 44, 3001
Leuven, Belgium
© The Minerals, Metals & Materials Society 2020
A. Siegmund et al. (eds.), PbZn 2020: 9th International Symposium
on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
https://doi.org/10.1007/978-3-030-37070-1_19
237
Plasma Slag Fuming Process
Samant Nagraj, Mathias Chintinne, Muxing Guo and Bart Blanpain
Abstract Submerged plasma slag fuming technology is a process intensification
of the traditional (coal-fired) slag fuming technology. A general dynamic model of
the plasma-driven slag fuming process has been developed in FactSage 7.0 based
on Metallo Belgium’s industrial scale submerged plasma slag fuming furnace. This
model describes the chemical reactions, phase equilibria and heat transfer in each
sub-unit operation, and the heat and mass transfer between the subsequent subunit operations of the slag fuming process. The model was validated on several
process batches. Upon assessing the simulation results, a deviation was found from
the industrial process, which can be explained using kinetic factors.
Keywords Metal extraction · Metal recycling · ZnO · FactSage
Introduction
Slag fuming is a reduction process to recover Zn from zinc-rich metallurgical residues
such as lead blast furnace slag, secondary copper smelter slag, and electric arc furnace
dust. The process involves three steps: (1) heating the slag over Zn vaporization
temperature, (2) reducing the ZnO in the slag by a reducing agent and evaporating
the Zn from the molten slag bath, and (3) cooling the Zn vapours to collect metallic Zn
condensate or oxidizing the Zn vapour with air to produce ZnO precipitates. Several
technologies have been developed over the years based on this principle, such as the
Waelz-kiln process, the Enviroplas process, and the QSL process [1–3].
In a conventional fuming process, the heating of the slag bath is generally done by
injecting product gases of combusted fossil fuel (typically, coal and natural gas) into
the reactor through side submerged tuyeres or a top submerged lance. The product
S. Nagraj (B) · M. Chintinne
Metallo Belgium N.V., Nieuwe Dreef 33, 2340 Beerse, Belgium
e-mail: samant.nagraj@metallo.com
S. Nagraj · M. Guo · B. Blanpain
Department of Materials Engineering (MTM), KU Leuven, Kasteelpark Arenberg 44, 3001
Leuven, Belgium
© The Minerals, Metals & Materials Society 2020
A. Siegmund et al. (eds.), PbZn 2020: 9th International Symposium
on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
https://doi.org/10.1007/978-3-030-37070-1_19
237