Got a rare earth deposit? Great. Got a mine? Even better. But do you have a processing plant? No? That could be a problem. The market doesn't understand how complex and expensive solid-phase rare earth extraction can be, but Metals Consultant Jack Lifton is here to put it into layman's terms in this interview with The Critical Metals Report. Lifton discusses processing innovations from North America, Germany and India that are changing the cost picture. He even names some companies that could see huge changes in their bottom lines in the coming years.
The Critical Metals Report: Jack, you have a chart listing 52 advanced rare earths projects. But in your last interview, you said that only five of the new HREE producers could be in production in the next three or four years, processing often being a significant hurdle. What makes HREE processing so difficult?
Jack Lifton: The major difficulty is separation costs for the individual elements. Because HREEs constitute such a small proportion of the rare earth element (REE) distribution in almost any deposit, companies are challenged with the task of separating all of the rare earths from each other to get any one of them in a useful form that can be sold to end users. In any REE deposit, half of it is typically made up of the REE cerium, which carries the least value of the so-called light rare earths (LREEs) because it trends to oversupply, but companies have to remove it anyway, which is an expensive process. On the other hand, dysprosium, a valuable, in-demand element, rarely makes up even 5% of a deposit. What happens in the La-La Land of the markets is that many investors do not understand that 50% of the concentration at your average rare earth deposit is not worth anything. They fail to realize that the composition of the ore matters more than the grade.
A hard rock rare earth ore with significant heavy rare earth content, which is now only found in Sweden, Norway, Finland, Canada and Brazil, first has to be concentrated mechanically, often by density to filter out the denser minerals. Some processes use gravity so the good stuff sinks to the bottom of a container. Flotation processes use chemical tricks so that the lighter materials float to the surface, where they can be skimmed, leaving the heavier stuff. These are well-known processes, but even if you are only interested in the heavy rare earth content, for example, you still must remove as much as 99% of the mass of the deposit to get to the less than 1% you wish to process chemically.
Let's say, in an ideal world, the mechanical concentration processes work. Now, you have the problem of extracting rare earth elements as ions out of those minerals that you've already separated. This is a chemical process. The mining industry has used simple chemistry for this for a long time, and it involves very widely available materials like sulfuric and hydrochloric acid. But what do you do if your mineral does not react to those commonly available solvents? You can always find an acid, a base or a combination of materials that will extract your material, but it's not necessarily economical. It can't be something exotic that's made in a laboratory or something that isn't available in the center of Mozambique, or wherever your mine is. You have to be practical.
Now, let's say you have completed step two and extracted a material. Let's say you even found a way to do it cheaply; maybe you can even recycle the acid. At this point, you have to look at how much you can extract through your chosen method. If you can only extract 10%, it's probably not worth it because even naturally concentrated ores are rather low grade. You have to work out a system to get the maximum yield. A good yield would be 70-90% of all the metallic ions in the ore body. Now you have to leave the laboratory and employ a full-scale leaching process. This will produce, finally, an ionic form of the metallic ions that you want. This mixture of every ion in the ore is called the process leach solution, or the PLS.
But it's still not over. Keep in mind that you have to separate not only all the rare earths from each other, but anything else that came along for the ride. With rare earths, that almost always includes iron, uranium or thorium. The problem is that uranium and thorium are bad actors. Thorium is genuinely the most radioactive element found in nature. Uranium is not as radioactive in nature as thorium is, but it too must be properly disposed of in a safe way. It can't just be removed and tossed aside.
TCMR: How do processors handle thorium and uranium safely?
JL: Traditionally, an operation like Mountain Pass would extract the thorium early on in the process from the PLS. It would extract thorium and LREEs so that they come out together, and then separate the LREEs from the thorium and/or uranium. When the thorium is finally isolated, then it is distributed in the process residue. This involves lowering the concentration as much as possible by dilution and producing a cement out of the thorium-laced mixture. This cement can be buried or put into pits. But when an ore has a lot of this material in it, even if there is a legal way to dispose of it, handling it is dangerous. Furthermore, miners need permits to handle radioactive materials and they need to prove that their process of extracting it, eparating it and mobilizing it all meet the standards. This is a huge expense. But you can't even get to processing rare earth PLS before you handle the thorium/uranium problem.