Oct 7, 2022

Interest grows in Steenkampskraal mine; highest grades of rare earths in the world

The Steenkampskraal project has many favourable attributes including its mining-friendly jurisdiction, well-developed local infrastructure with established access.

By Trevor Blench, chairman of Steenkampskraal Holdings, which owns the Steenkampskraal rare earths mine in the Western Cape, South Africa.

Because rare earths are used for so many commercial applications, the US, Japan, Europe and many other countries could be vulnerable to supply disruptions.

Steenkampskraal’s vision is to be the building block of a rare earths supply chain independent of China.

Manufacturers as well as countries around the world are indicating concern over China’s dominance of these strategic elements. The concentration of rare earths production in China raises the question of supply vulnerability.

Rare earths are considered essential to a country’s national security and economic well-being.

The rare earth elements (REEs) deposit at the Steenkampskraal mine has been confirmed to be the highest grade in the world, at 14.4% (REE), with the rare earth grade in some areas as high as 45% TREO + Y2O3 (total rare earth oxides + yttrium oxide).

The Steenkampskraal project has many favourable attributes including its mining-friendly jurisdiction, well-developed local infrastructure with established access to the underground mine, high-grade REE orebody, continued exploration potential, and low capital requirements.

The project was successfully exploited for thorium in an underground operation by Anglo American between 1952 and 1963.

The Steenkampskraal mine holds the full spectrum of rare earths including high-value neodymium (Nd) used in the manufacture of magnets, computers and hard drives.

Typically, a 3-megawatt wind turbine uses about 500 kg of neodymium and 100 kg of praseodymium in the magnets for its motors.

Lanthanum and cerium are used in nickel metal hydride batteries and there is potential demand for tens of thousands of tons of rare earths for hybrid and fully electric vehicles over the next few years.

A typical hybrid car uses 10 kg of rare earth metals. Hybrid electric motors use dysprosium and terbium, and their component sensors use yttrium.

Most rare earth deposits that have been found around the world have an average in-situ grade of between 1% and 3%.

If and when these deposits are mined, the recovered grades will be even less because the in-situ mineralised material will be mixed with material (waste rock) that has little or no economic value (the mining cut).

Hard rock monazite deposits, such as the deposit at Steenkampskraal, generally have much higher grades compared to beach sand deposits.

Rare earths in India, Australia and many other countries are mainly contained in heavy mineral sand deposits, while in China they are found mainly in bastnaesite, a mineral that is associated with iron ore.

When rare earths are contained in low-grade sand deposits, the extraction process is more difficult and costly when compared to rare earths contained in high-grade, hard-rock monazite deposits.

In most monazite resources in the world, the monazite is disseminated in heavy mineral sands and the monazite grade is diluted – whereas at Steenkampskraal the monazite (REE) mineralisation is concentrated in a reef zone between 0.02m to over 10 m thick, with an average thickness of nearly 1 m, making it easier to separate and extract the monazite.

Grades are dependent, amongst other factors, on the minerals in which the rare earths are contained and how the minerals are distributed within the host rock. Because of Steenkampskraal’s high grade, it is not necessary to extract huge amounts of ore and therefore large crushing vessels are not required.

Another feature of the Steenkampskraal deposit is the size of the monazite grain carrying the rare earths.

The grain is larger than normal, at about 250 to 300 microns in diameter.

This means that the monazite requires less milling, further reducing costs. Most monazite needs to be milled down to 50 microns. This increases costs and requires large amounts of energy.

In addition, 59% of the mass of the monazite is total rare earth oxides. As a result, when milling due to the high percentage monazite mass, less dust is created because of the high density, further reducing costs and lessening any negative environmental impact.

The chemical treatment process is also less complex resulting in reduced capital and operational expenditure.

The Steenkampskraal mine has great value and economic potential. The mine’s rare earths basket, based on present prices, is about US$15.84 per kilo of separated rare earth oxides.

The cost of the mine’s production is estimated at US$9.64 per kilo of separated rare earths. Gross profit is estimated at US$6.20 per kilo.

With these prices and volumes, the company would have a total sales value of US$43 million per year, total costs of about US$26 million per year and a gross profit around US$17 million per year.

Steenkampskraal has a Mineral Resource Estimate of 605 000 tons at an average grade of 14.4% total rare earth oxides (TREO) for a total of 86 900 tons of contained TREO.

Feature image credit: Wikimedia

Hits: 176