To enable a major shift to bring transportation and power to greenhouse gas neutrality the coupling of both sectors for the first time in history is mandatory: batteries can enable 30% of the required reductions in carbon emissions in the transport and power sectors. However, the supply of the raw metals for batteries is precarious because of limited natural reserves of several raw materials and their local distribution. According to data provided by the United States Geological Survey, Li reserves are concentrated in a few countries (8 million tons in Chile, 2.7 million in Australia, 2 million in Argentina, and 1 million in China), with the possibility of a crisis in the availability of this raw material and the following market instability of the related goods. Thus, technologies that can stably secure strategic metals must be developed, as for example urban mining, which allows recovery of metals from secondary sources. However, at the moment, the waste recovery processes of battery wastes are complicated and require high resources consumption in terms of energies and chemicals necessary for metals extraction.
The new proposed carbotermic technology is based on microwave (MW) radiation. The method is based on a new hybrid heating mechanism, designed to substitute pyrometallyrgical classical methods.
The idea was patented by the University of Brescia – UNIBS (www.unibs.it) and the Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali – INSTM (https://www.instm.it/)
Carbothermic reductions are metallurgical processes for reduction of metallic oxides to metal. The usual reduction agents are coke, petroleum coke and charcoal. This reaction generally occurs at 1000 °C or more. In a general view, coke reduces the metallic oxide (MenOm) to metal (Me) and carbon monoxide (CO), by a direct solid phase reaction:
MenOm+mC→nMe+mCO
This reaction makes it possible to recover metals. However, in comparison with conventional heating methods, MW heating has the advantage of faster and uniform heating and higher sustainability.
