Dr. Jérémy Chaulet

Abstract:

Recyco, part of the Aperam group, built its pyrometallurgical recycling expertise by recovering valuable elements from stainless steel meltshop dusts. Since 2019, a real evolution of the site started, following the receival of an extended environmental permit allowing the treatment of a broader range of wastes, including hazardous ones. This capability expansion goes along with the development of new processes and products, and is now a real asset for the ongoing transformation of Aperam into a climate-neutral stainless steel producer.

The production of high Ni containing alloys from a multitude of different wastes is described in this paper. This case study is an excellent example of cooperation between R&D and operations, supported by internal customers and aided by sourcing, legal and environmental teams. The development started with preliminary design and simulation of the process using thermodynamic simulations [1, 2]. Slag design and reduction equilibria studies were an important part of the fundamental investigation. Lab-scale experiments supported this development, before a step-by-step transfer to operations, following learning cycles and inspired by the minimalist approach [1], was performed. These cycles are closed by the comparison of the experimental and industrial results to the thermodynamic simulations, and the generated knowledge has been used as the basis for an in-house developed process model of our operation. This model now allows us to simulate the behavior of new wastes in our process, reducing the risk of downtime and production being out of speciation. 

The produced alloys are in line with our meltshop specifications replacing primary nickel. As these alloys have a significantly lower CO₂ footprint than primary Ni units normally used, Recyco is transforming into an important player in reducing Aperam’s scope 3 emissions.