If one studies the economic geology of Rare Earth Elements (REE), it becomes clear that REE’s are frequently (usually?) found in deposits rich in other elements. Deposits of zirconium, tantalum and niobium, for instance, are frequently co-located with REE’s.
The REE’s are found in ore bodies that are naturally enriched in either heavies (yttric or HREE’s) or lights, (ceric or LREE’s). The LREE’s seem to be the most common spread of the REE’s. Molycorp’s Mountain Pass bastnasite deposit is a good example of this.
What is not so widely known is that thorium and/or uranium are nearly always found in these deposits. This might be regarded as a good thing except that companies in the REE business seem to be less interested in actinides than lanthanides. The actinide business is fraught with complications related to the natural radioactivity of Th and U. If one is interested in rare metal production, the matter of radioactivity is unwelcome.
However, there is opportunity here if certain institutional thinking is allowed to expand. I refer to the global preference for uranium and plutonium in the nuclear fuel cycle. Nearly the entire world’s nuclear materials infrastructure was directed to the production of yellowcake and separation of U235 from U238 post WWII. While there has been some experimentation with thorium 232 in the US, and there are some limited initiatives in motion, it has been largely neglected in reactor design and the fuel cycle in favor of uranium and plutonium.
Rare earth element mining and processing naturally produces thorium and uranium. At present, those practicing REE extractive metallurgy have every incentive to avoid concentrating the actinide components owing to the radioactivity. However, if there were a coherent program for the development of an efficient thorium fuel program, this natural resource could be efficiently taken from the REE product streams now or in the future.
Our reliance on energy will trend substantially towards electricity. The greater absolute abundance of Th over U, as well as the ability to use 100 % of the predominant isotope makes thorium a good candidate for energy exploitation. The recent boom in REE exploration has uncovered new sources of thorium. The nuclear genie was let out of the bottle nearly 70 years ago. By now we should be a little smarter about how we use it.