Metals and alloys are among the most technologically important materials for our industrialized societies. They are the most common structural materials used in cars, airplanes and buildings, and constitute the technological core of most electronic devices. They allow the transportation of energy over great distances and are exploited in critical parts of renewable energy technologies. Even though primary metal production industries are mature and operate optimized pyrometallurgical processes, they extensively rely on cheap and abundant carbonaceous reactants (fossil fuels, coke), require high power heating units (which are also typically powered by fossil fuels) to calcine, roast, smelt and refine, and they generate many output streams with high residual energy content. Many unit operations also generate hazardous gaseous species on top of large CO₂ emissions which require gas-scrubbing and capture strategies for the future. Therefore, there are still many opportunities to lower the environmental footprint of key pyrometallurgical operations. This paper explores the possibility to use greener reactants such as bio-fuels, bio-char, hydrogen and ammonia in different pyrometallurgical units. It also identifies all recycled streams that are available (such as steel and aluminum scraps, electronic waste and Li-ion batteries) as well as the technological challenges associated with their integration in primary metal processes. A complete discussion about the alternatives to carbon-based reduction is constructed around the use of hydrogen, metallo-reduction as well as inert anode electrometallurgy. The review work is completed with an overview of the different approaches to use renewable energies and valorize residual heat in pyrometallurgical units. Finally, strategies to mitigate environmental impacts of pyrometallurgical operations such as CO₂ capture utilization and storage as well as gas scrubbing technologies are detailed. This original review paper brings together for the first time all potential strategies and efforts that could be deployed in the future to decrease the environmental footprint of the pyrometallurgical industry. It is primarily intended to favour collaborative work and establish synergies between academia, the pyrometallurgical industry, decision-makers and equipment providers. Graphical Highlights: A more sustainable production of metals using greener reactants, green electricity or carbon capture is possible and sometimes already underway. More investments and pressure are required to hasten change. Discussion: Is there enough pressure on the aluminum and steel industries to meet the set climate targets? The greenhouse gas emissions of existing facilities can often be partly mitigated by retrofitting them with green technologies, should we close plants prematurely to build new plants using greener technologies? Since green or renewable resources presently have limited availability, in which sector should we use them to maximize their benefits?

The discovery of new metallic materials is of prime importance for the development of new technologies in many fields such as electronics, aerial and ground transportation as well as construction. These materials require metals which are obtained from various pyrometallurgical processes. Moreover, these materials need to be synthesized under extreme conditions of temperature where liquid solutions are produced and need to be contained. The design and optimization of all these pyrometallurgical processes is a key factor in this development. We present several examples in which computational thermochemistry is used to simulate complex pyrometallurgical processes including the Hall–Heroult process (Al production), the PTVI process (Ni production), and the steel deoxidation from an overall mass balance and energy balance perspective. We also show how computational thermochemistry can assist in the material selection in these extreme operation conditions to select refractory materials in contact with metallic melts. The FactSage thermochemical software and its specialized databases are used to perform these simulations which are proven here to match available data found in the literature.

This paper presents investigations on the thermodynamic stability of the Al13Fe4 solid solution in the Al-Fe-Mn ternary system as well as its crystal chemistry characterisation. In order to carry out this study, the isobaric heat capacity of the solution was measured at high temperature using a high precision three-dimensional probe. The heat capacity of the Al13Fe4 binary compound measured in this study between 600 K and 1223 K is CP(T) = 23.97 + 8.18.10−2T − 7.63.105T2. This value is significantly different from other measurements in the literature and we show in this paper that our measurements are not only more accurate than those in the literature but also more thermodynamically consistent with all other measurements and calculations of the enthalpy of formation of this phase. Measurements of the enthalpy of formation of the solid solution were also performed by in − situ synthesis in a DSC. These new measurements were complemented by DFT calculations of the enthalpy of formation at 0 K of the solid solution. Our calculations and measurements show that the substitution of Fe by Mn is responsible for a large increase in the solid solution enthalpy of formation. These new experimental and calculated data were used to develop a thermodynamic model of the solution. Finally, we utilized our model to calculate the Fe sof of the solid solution structure over its entire chemical composition range (simulating the complete substitution of all Fe atoms with Mn) as a function of temperature. The chemical ordering of the solid solution was thus quantified, revealing its ideal nature near its melting temperature. These results allowed the development of a new SL-model for the solution, both simpler and more reliable than those used in the literature.