How large is the deposit of REE in The Fen Complex?
Author: Tor Espen Simonsen
Published: 14 Nov, 2023
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Updated: 28 Dec, 2023
In order to gain a better understanding of the Fen Complex's deposit of REE, it may be relevant to take a closer look at these factors:
In addition, it is important to take a closer look at what kind of tailings* and by-products mining can lead to.
The Fen Complex is described as a very large deposit in a global context, and is probably by far the largest in Europe. A conservative estimate suggests that the Fens field contains between 30 and 50 million tonnes of rare earths (TREO*). In comparison, LKAB* has reported that the Per Geijer field at Kiruna may contain 1.32 million tonnes of TREO.
According to the USGS , the total production of rare earths in the world was 300,000 tonnes in 2022.
Although the grade (gehalten) of REE in the Fen Complex is described as good, it may be somewhat lower than in some other known deposits in the world, such as Bayan Obo in China and Mountain Pass in the United States. It is believed that the average grade of rare earths in Fen is between 1 and 2 percent, with several richer zones at 3 to 5 percent. In the map above, the green-marked 'belt' is assumed to have the highest concentration of REE.
It can be challenging to grasp the significance of these percentages, and an grade of 1 or 2 percent may appear low. It is often helpful to consider such figures in relation to other well-known mineral projects:
On Fen, it is the volcanic rock rauhaugite (Fe-dolomite-carbonatite) that is of interest.
In the rauhaugite, the rare earths are bound in phosphate (monazite) and fluorocarbonates (bastnäsite). These are the same minerals that rare earths are traditionally mined from elsewhere in the world. For example in the USA and China.
Although the concentration on Fen is «only» 1 to 2 percent on average, the rare earths appear in clusters or lumps. This can be favorable for extraction and separation.
In the red rock, that dominates the old iron mines on Fen, there are also rare earths, but here they appear much finer grained and are therefore difficult to extract. At the same time, the content of radioactive thorium is higher in the red rock.
Another factor of interest in understanding the deposit in Fen relates to the distribution of the 17 rare earth species. Market prices vary significantly from one element to another, with the 'magnetic' metals like dysprosium and neodymium having the highest value.
Given that Fen shares important similarities with active deposits in the USA, China, and Australia, we can anticipate a similar proportion of key metals in Fen. This aligns with reports from researchers and licensees (companies) in the Fen area. Thus far, the consensus has been that the Fen Complex contains a 'healthy' amount of the most valuable raw materials
A final picture of how the various metals are distributed in the area of Fen will only come when the licensees have documented their deposits in more detail.
The mineral deposits of rare earth elements constitute only a small percentage of the ore. This implies that large volumes of tailings and waste rock must be managed once the valuable minerals have been extracted.
This will likely involve the implementation of three parallel techniques:
1) development of by-products
2) backfilling of tailings in the mine
3) on-land disposal
The rock type that contains rare earth minerals is often referred to as rauhaugite (re-dolomite-carbonatite). It primarily consists of carbonates (80 to 90 percent). NGU states that carbonate minerals, such as limestone and dolomite, are "Norway's most important industrial mineral group". Carbonate minerals are utilized in various industries, including the paper industry, cement production, and environmental applications such as acid neutralization. There is a potential opportunity to produce marketable by-products from the surplus materials at Fen.
By-products can reduce the need for on-land disposal and enhance the financial viability of a mine. However, these by-products must meet cleanliness standards, and there will be a requirement to separate out radioactive thorium. Achieving this will be one of several critical success factors for mining in the Fen Complex.
Fensfelet.no is owned by Nome municipality and Midt-Telemark og Nome utvikling AS (MTNU). The purpose of the website is to provide good and objective information about the Fen Complex to anyone who is interested.
