Note: This article corrects an earlier version published by Roskill that contained an error on Silmet’s licence status and volume, clarifies terminology around NORM vs. radioactive residues and a potential reader inference that Silmet is not producing niobium and tantalum when it in fact continues to do so.
A proposal to ship tantalum/niobium (Ta/Nb) processing residues from Neo Performance Minerals’ (NPM) ongoing Ta/Nb production at its Silmet plant in Estonia to the USA has now reached the public consultation stage, with the deadline for comments being July 10th, having been extended from June 5th. Energy Fuels, which seeks to recover uranium from NPM’s Ta/Nb process residues, expresses confidence in the permit’s eventual approval by the State of Utah. However, if the permit is not approved, NPM will be seeking alternatives to deal with its residue, a process that could impact its ability to process columbite and columbite-tantalite mineral concentrates in future, potentially leaving the company more heavily reliant on pre-processed concentrates for its refined output.
“We look forward to Energy Fuels obtaining its proposed permit modification so that uranium contained in Silmet’s tantalum and niobium production residues can be recovered for low-carbon nuclear power use,” said Jim Sims, spokesman for NPM. “Recycling our residual material streams whenever possible into useful materials is a priority for NPM and our commitment to sustainability.”
NPM Silmet produces niobium and tantalum metal and has a 700tpy capacity, mostly dedicated to niobium. For many years its raw material feedstock has come from a FeNbTa alloy produced in Brazil by Mineração Taboca and from the niobium mineral columbite mined in Nigeria. Supply from Taboca was disrupted in 2016 and imports from Nigeria were supplemented by Brazilian columbite and by columbite-tantalite from Central Africa. Supply from Taboca resumed in 2017. In 2019, Estonia imported material only from Taboca as its feedstock and still does, with production continuing normally. There were no imports of mineral concentrates according to international trade data.
There is an important difference between the two types of feedstock used by Silmet. Tantalum and niobium minerals almost invariably contain low levels of the radioactive elements uranium and thorium. These elements remain in the processing residues but are not present in the processed product. In the case of the FeNbTa alloy, processing is undertaken in Brazil and the residues remain with Taboca. With regard to Ta/Nb concentrates, a combined uranium and thorium content above 10bq/g renders material Class 7 under the NORM (Naturally Occurring Radioactive Materials) system.
Strictly speaking, Ta/Nb concentrates contain small amounts of radioactive elements, as do the residues generated by processing. The word ‘radioactive’ is very emotive, however, and can easily lead to over-exaggerated perceptions. A crude but commonly cited illustration is that of the banana. A typical banana is considered to have 15bq/g (Brazil nuts are even higher). That is above the NORM cut-off. For all practical and human safety purposes, the radioactivity level of Ta/Nb concentrates and residues is insignificant.
An important issue is what is defined as ‘waste’. Processing of mineral feedstock results in a usable/saleable product and a residue. In the case of a single product and no used residue, Roskill would define that residue as waste. It is often the case that mineral processing generates co-products or by-products that are used or sold. Such materials, sometimes called alternate materials, can reasonably be described other than as waste.
Processing of mineral concentrates at Silmet generates residues containing low levels of uranium and thorium. These have been stored at its facility. The company has a licence to store 660t of the material. The Ministry of Environment of the Republic of Estonia has stated that Silmet must demonstrate that it has arranged with an off-site facility appropriately licensed for reprocessing/disposal of the material before it will renew the company’s permit to import NORM-containing Ta/Nb concentrates. Roskill understands that there is no such facility in Estonia.
Energy Fuels, of the USA, has applied for a permit to import the material for processing to uranium yellowcake at its White Mesa uranium mill in Utah. It already processes such material from elsewhere in North America, including from other rare metal and rare earth mineral processors. Roskill notes that Energy Fuels employs the term ‘alternate feed materials’ while indicating in its annual report that such material is usually classified as waste.
Key to the permitting process is public consultation. The closing date for public comments nears. It is too soon to know the likely results. The local Ute Mountain Tribe has been critical of the mill and its waste containment cells, expressing concerns about potential health and environmental impacts on the nearby reservation community of White Mesa. However, Energy Fuels expresses that it operates safely and in compliance with all applicable laws and that it has confidence that the permit will be approved by Utah authorities. Silmet reported to Roskill that is has alternative options for processing Silmet residue in the event Energy Fuels is not successful in receiving a permit to import it.
Roskill’s Niobium: Outlook to 2029, 15th Edition and Tantalum: Outlook to 2029, 15th Edition reports are available for subscription; click here to find out more. Updates for both commodities, highlighting the effects of COVID-19 on supply and manufacturing chains, will be available to subscribers in June.