Hydrometallurgy

Tell us briefly about yourself and how you came to do your doctorate.
I graduated in 2018 from the predecessor to the “Sustainable Process and Chemical Engineering” programme at LTU. I then worked in the mining and steel industry for almost six years, where I held various engineering positions in both production and research. I always had the idea of doing a PhD one day, but I was waiting for a suitable topic. Now the opportunity arose to do a PhD in a growing and exciting field that will become even more important in the future.

What is sub-project 12 "Improved hydrometallurgical process for the recovery of black mass from lithium-ion batteries" about?
The project is about developing a new method for recycling black mass, a fine powder that originates from lithium-ion batteries and contains valuable metals such as lithium, nickel, manganese and cobalt. The current recycling method is based on leaching, in which the powder is dissolved with sulphuric acid, after which the metals are separated using a method called solvent extraction. This method has some inherent disadvantages. Solvent extraction requires hazardous and environmentally harmful solvents that are based on fossil raw materials. It is also a rather expensive and flammable process.

Northvolt is your industrial partner. What is it like to work with them?
The collaboration with Northvolt works well. We have regular meetings where we discuss the project and discuss any problems we have encountered during our experiments in the lab. Northvolt provides both technical expertise and material for the project.

What can be recycled from a lithium-ion battery?
Plastic, copper and aluminium are examples of material streams from the mechanical recycling of lithium-ion batteries. This means that the batteries are cut into pieces and then separated by sieving and various physical methods. Black mass, graphite and electrolyte are further examples of material streams from recycling. These often have to be further processed using both mineralprocessing and pyro- and hydrometallurgical methods before they can be used to manufacture new batteries.

What are you investigating now in comparison to a conventional recycling method?
We are investigating whether a technique called electrodialysis can replace or supplement solvent extraction in separating the metals after leaching out the black mass. In electrodialysis, a difference in electric potential across a series of ion-selective membranes is used to separate the metals. The main advantage is that less hazardous chemicals are required compared to solvent extraction. This in turn makes for a more environmentally friendly process. Electrodialysis has the potential to become a green alternative to solvent extraction.

What results do you hope to achieve?
We hope to recover as much metal from the black mass as with solvent extraction. At the same time, we want to achieve a high product quality so that the metals can be used for production of new batteries. Then, of course, it is important that our method becomes an economically viable alternative to solvent extraction.

Can you say something about possible challenges and obstacles?
Electrodialysis has not yet been used industrially in this type of application. Traditionally, it has been used to desalinate seawater for production of drinking water or to produce table salt. One challenge is to prevent precipitation on the membranes, otherwise there is a risk that they will not function properly. Another challenge is the water balance, i.e. limiting the amount of water, which is important from both an environmental and economic point of view. We want to minimise the amount of residual products and possibly valorise the residues that are produced.