A new way to produce metal and alloys has been developed which would make a process responsible for 10 percent of the world CO2 emissions climate-neutral.
Scientists from the Max Planck Institute for Sustainable Materials in Germany have presented a new design concept that combined the extraction, mixing and processing of metallic materials in a single process step.
Research fellow Shaolou Wei said the process also used hydrogen instead of carbon as an energy source and reducing agent, so no CO2 was produced during production.
Dr Wei said the metal ores were processed into ready-to-use alloys at just 700 degrees Celsius, without repeated heating and cooling.
He said this saved 40 percent energy compared to conventional metallurgy.
“Metal production is responsible for 10 percent of global CO2 emissions, with iron production emitting two tons of CO2 for every ton of metal produced, and nickel production emitting 14 tons of CO2 per ton and even more, depending on the ore used.”
Dr Wei said these metals formed the foundation of alloys critical for the aerospace, cryogenic transport, energy and precision instrument sectors.
He said conventional alloy production was typically a three-step process, with each step energy-intensive and relying on carbon as both an energy carrier and a reducing agent, resulting in significant CO2 emissions.
“The key idea is to understand the thermodynamics and kinetics of each element and use oxides with similar reducibility and mixability at around 700 degree Celsius.
“This temperature is far below the bulk melting point, which still allows us to extract metals from their oxide states and mix into alloys via one single solid-state process step without reheating.”
He said unlike conventional methods where ores were reduced using carbon, which resulted in carbon-contaminated metals, the team’s new method used hydrogen as the reducing agent.
Fellow researcher Dierk Raabe said using hydrogen instead of carbon had four key advantages.
“First, the hydrogen-based reduction only produces water as a byproduct, meaning zero CO2 emissions.
“Second, it yields pure metals directly, eliminating the need to remove carbon from the final product, thus saving time and energy.
“Third, we do the process at comparably low temperatures, in the solid state (and) fourth, we avoid the frequent cooling and reheating characteristic of conventional metallurgical processes.”
Read the full study: One step from oxides to sustainable bulk alloys.
