Technoeconomic Assessment of BAAM for NdFeB Magnets (Additive Manufacture vs. Molding.)

[NNadir]

The paper to which I will briefly refer is this one: Comparative Techno-economic Assessment of NdFeB Bonded Magnet Production: Injection Molding versus Big-Area Additive Manufacturing Xiaoyu Zhou, Mariappan Parans Paranthaman, and John W. Sutherland ACS Sustainable Chemistry & Engineering 2023 11 (36), 13274-13281

As the title of the paper makes clear, BAAM is "Big Area Additive Manufacturing." This is a big area of research at Oak Ridge National Laboratory. They have demonstrated printing nuclear reactor cores there.

Although Oak Ridge is a center for the development of nuclear technologies the paper begins with text including an adjective phrase I find dubious, which includes (as bolded by me) statements about wind turbines and electric cars being effective approaches to doing away with fossil fuels.

To wit:

The demand for energy, such as electricity, around the world is increasing, with much of this demand being met through the use of fossil fuel resources. Of course, the use of fossil fuels for energy production leads to the emissions of greenhouse gases to the atmosphere that are linked to climate change. Moving away from fossil fuels requires the development and deployment of clean energy technologies such as wind turbines and electric vehicles (EVs). (1) These technologies are often reliant on high-performance rare earth permanent magnets (REPMs). The past two decades witnessed a surge in REPMs with them reaching a market value of $14.4 billion in 2020 (representing about 70% of the global permanent magnet market value), compared to a 35% market share in early 2000s. (2,3) Currently, around 90% of the rare earth supplies come from China. (4) The near-monopolization of the rare earth element supply and processing makes the supply chain volatile. For example, when China cut the export quota of rare earth elements by 40% in 2010, some rare earth material prices increased by two, three, or even ten times in 2011 over their previous levels. (5,6) The U.S. Department of Energy (DOE) examined and analyzed the criticality of rare earth elements and 00other key strategic materials, and concluded that neodymium and dysprosium are the most critical rare earth metals with respect to clean energy technologies. (7) Moreover, the pandemic made things worse, as hundreds of mines were partially, if not wholly, closed. While the effects of the pandemic on metal markets seem to be ebbing, the prices of such materials as neodymium and dysprosium are likely to remain subject to substantial supply risk moving forward due to soaring demand and competition for constrained material supplies. (4,8)

Given the supply risk associated with rare earth elements and associated price volatility, a number of strategies are being pursued globally to limit the risk, e.g., finding new sources for these critical materials and developing material alternatives. One strategy that seems to offer promise with respect to REPMs is to recover magnets from end-of-life (EOL) products and capture magnet waste during sintered magnet processing. It is envisioned that such reclaimed materials could be used to fashion “new” magnets and, thus, temper the demand for virgin resources. A comparative life cycle assessment of producing magnets from virgin materials and through magnet-to-magnet recycling showed that recycling is an environmentally preferable choice. (9) Furthermore, recycling is also preferred with respect to magnet performance since it enables the adaptation to newly discovered methods that improve magnet strength and ductility. (10)

I have also high lighted the word dysprosium, which I discussed in this space recently: Unlocking Dysprosium Constraints for China's 1.5 C Climate Target

Even in China, which dominates the world supply of lanthanides, there isn't believed to be enough dysprosium to build all these bat and bird chopping wind turbine industrial parks that are supposed to save the world, but haven't done so, aren't doing so, and I contend, because of their lack of sustainability, won't do so.

Still we chant on.

Electricity is a thermodynamically degraded form of energy, but within limits well below all the associated fantasies about its sources (which are dominated by dangerous fossil fuels), electricity is a very valuable form of energy, as any fool, even me, can see. In modern times its generation is dominated by NdFeB magnets. The constraints of the supply of these make it extremely dubious to put them in wind turbines, since the materials in a wind turbine are all stranded assets when the wind isn't blowing, but no matter. It follows that the best use of limited resources is in reliable clean systems with high capacity utilization, that is in nuclear plants.

It takes a lot of energy to make these magnets, some of which is heat energy.

Some additional text from the paper:

...There are three methods to produce NdFeB magnets: sintering, bonding, and hot deformation. (11) Only the first two methods have been successfully commercialized. (12) The manufacturing of sintered NdFeB magnets starts with strip casting where the alloy is melted in a furnace at around 1000 °C and then processed and quenched in a strip caster into sheets. (13,14) Strip casting avoids the unwanted α-Fe phase through rapid cooling. (15) The cast alloy sheets are then rolled and pulverized into a fine powder. The powder is pressed into a green compact in the presence of a magnetic field. The green compact then goes through the thermal process of sintering, followed by finishing with machining, magnetizing, and coating to prevent corrosion. A sintered NdFeB magnet has a maximum energy product (BHmax) of around 200–400 kJ m^–3, making it the highest available magnetic performance from NdFeB. However, the brittleness of sintered magnets requires careful handling and limits the magnets to simple geometries. (16) Further machining sintered magnets to produce complex shapes will produce a lot of magnet wastages...

...

A bonded magnet contains a mixture of magnetic powder and nonmagnetic polymer or rubber binder. (17) There are four methods to manufacture bonded magnets: compression bonding, injection molding, extrusion, and calendaring. The end products of compression and injection molding are rigid magnets, which provide good magnetic performance and are not excessively brittle; these processes are generally economically competitive. Calendaring can produce only flexible magnets. Both flexible and rigid magnets can be produced using extrusion...

...Manufacturing magnets through compression bonding starts with melt spinning, which melts NdFeB ingots. The molten alloy is poured into a tundish and directed onto the surface of a quench rim to form a ribbon through the nozzle at the bottom of the tundish. To get a finer grade of the powder (less than150 μm), the ribbon is crushed and annealed in an inert atmosphere. Then, the crushed powder is encapsulated or blended with the bonding resin. After that, the epoxy encapsulated powder is compacted into a green compact of the desired shape...

Getting to the point, BAAM:

...While there are many studies focusing on the improvement of magnet properties and manufacturing processes, few have examined the economics and environmental impact of industrial magnet production. This is especially the case for the newly developed BAAM process. BAAM has been reported to have produced magnets with comparable or even better performance than IM magnets. (21) A recent life-cycle assessment comparison of BAAM and IM indicated that BAAM has a smaller environmental impact; however, an economic comparison has yet to be reported; this is the focus of this paper. Moreover, a comparative techno-economic analysis may shed light on the industrial feasibility of these processes...

A table comparing the mass and energy intensity of two processes for magnet manufacture, injection molding and BAAM:



Another table and picture from the text:



The profitability is a function of scale, apparently, with BAAM scales being slightly less profitable than injection molding on current scales but in terms of energy consumption and material costs, BAAM is superior and cleaner and may ultimately be more profitable.

The authors conclude:

...The comparative TEA results show that producing NdFeB magnets using the BAAM method has better economic performance than IM (profit is 10% higher). Although the BAAM equipment is more expensive than the IM equipment, the increased capital cost for BAAM is more than made up through energy and material savings. That being said, owing to the fact that BAAM is a new technology, the price of BAAM equipment may rise in the years ahead. An increase in the price of BAAM equipment by more than a factor of 1.4 will cause the BAAM method to lose its economic advantage over IM. Both the environmental impact and economic analyses indicate that BAAM is superior to IM....

I trust you're enjoying the weekend.