Snowwhite2 paper: Separating critical elements from a NdFeB magnet

Welcome back to our series showcasing the incredible influence of the Snowwhite SLS 3D printer on scientific progress! Our focus today is on a paper titled “Separating critical elements from a NdFeB magnet with aminophosphonic acid functionalised 3D printed filters and their detailed structural characterisation with X-ray tomography.”

To make sure everyone can understand this important work, we’ll first break down what the study aimed to achieve and what its key discoveries were, all in plain language. If you’re looking for the nitty-gritty details, the original abstract and supporting references will follow.

Understanding the study and its main result

This research looked at 3D-printed filters designed to separate valuable elements from old magnets. These filters are made mostly of a common plastic called nylon, with a special additive. Two different additives were tested: one that’s commercially available (Lewatit TP260) and another that was newly created (called aminobisphosphonic acid (1)).

First, they dissolved the old magnets using a mild acid. Then, they tested how well the filters could pick up different elements. The filters with the commercial additive (Lewatit TP260) were much better at grabbing rare earth elements (like Neodymium, found in magnets) compared to other metals. They were also more effective than the filters with the newly created additive.

Because of their strong performance, the PA-TP260 filters were chosen for the main separation process. Here’s how it worked:

• Iron was removed first by causing it to settle out of the solution.
• Then, the remaining elements were separated into four different groups using the filters: rare earth elements, boron and cobalt, copper, and aluminum.

A big discovery was that these filters are very durable and reusable. They could be used for 50 cycles of adsorbing and releasing elements without losing their effectiveness or changing their structure. This means they’re robust and can be used repeatedly.

Main result

The key discovery is that these 3D-printed filters, specifically those containing the Lewatit TP260 additive, can efficiently and sustainably separate critical elements from recycled magnets. This is significant because:

• They use environmentally friendly chemicals (like methanesulfonic acid) for the separation process.
• The filters are highly reusable and robust, making the process more cost-effective and sustainable in the long run.

Essentially, they’ve found a greener and more efficient way to recover valuable materials from electronic waste.

Separating critical elements from a NdFeB magnet with aminophosphonic acid functionalised 3D printed filters and their detailed structural characterisation with X-ray tomography

Emilia J. Virtanen, Janne Yliharju, Esa Kukkonen , Tia Christiansen, Minnea Tuomisto, Arttu Miettinen, Ari Väisänen, Jani O. Moilanen

Ref.: https://chemrxiv.org/engage/chemrxiv/article-details/677f6c57fa469535b94858e1

Abstract

3D printed filters containing 70 wt% of polyamide (PA) nylon-12 as a polymer matrix and either 30 wt% of a commercial aminophosphonic acid functionalised resin (Lewatit TP260) or a synthetized aminobisphosphonic acid (1) as an additive were investigated for the separation of elements from a NdFeB magnet waste. Before separation studies, the magnet was leached with 10 v/v% methanesulfonic acid using S/L ratio of 5 g/l for 20 h at 60 °C. The PA-TP260 filters adsorbed rare earth elements (REE) more efficiently than transition and main group elements and showed greater uptake than the PA-1 filters at the studied pH range of 0.15–4.00. Thus, the PA-TP260 filters were selected for the separation process, wherein Fe was selectively precipitated from the leachate, while solid-phase extraction was used to separate the remaining elements from the leachate to four distinct fractions: REEs; B, Co; Cu; and Al. Neither significant decrease in the adsorption and desorption percentages of the PA-TP260 filters over 50 adsorption-desorption cycles, nor structural changes, as confirmed by the detailed X-ray tomography studies, were observed. The results indicate that the PA-TP260 filters are robust and fully reusable. Overall, the results demonstrated that the highly porous 3D printed filters efficiently separate critical elements from the NdFeB magnet leachate only by using ecofriendly MSA, ammonium chloride, and potassium oxalate solutions paving the way towards greener separation processess for the critical elements.