When mined, rare earths are high lustre metals which are typically silver, silver-white, or grey in colour. When exposed to the air they tarnish and form oxide compounds. Rare earths, when found in a large enough cluster, are actually a ‘cocktail’ of elements which have to be separated into individual elements before they can be used commercially. Rare earths tend to be mined using open pit methods. Once extracted from the ground, they can be supplied in elemental form. Alternatively they can be processed into compounds (oxides, chlorides, and carbonates) which are collectively referred to as REOs.
How We Mine Rare Earths
Our Mt Weld mine produces high-quality rare earth concentrate from one of the world’s richest deposits, due to the high relative concentrations of neodymium, praseodymium, and europium.
The main deposits are hosted within what is called the soil/regolith horizon, which blankets a layer of the mine that comprises carbonatite. This forms shallow lenses and sheets which are generally located within 60 metres of the surface. Our most important rare earths source, the Central Lanthanide deposit, is located at the centre of the carbonatite while the niobium, tantalum and other deposits are generally located towards the outer fringes.
Lynas’ initial mining activities were successfully completed in June 2008. During this campaign, we mined 773,300 tonnes of ore with an average grade of 15.4 per cent REO. We stockpiled this ore on site according to its grade and mineralogy ready for downstream processing.
In September 2011, we were granted permission by the Western Australian authorities to extend our drilling program to the western side of the Central Lanthanide deposit. In that same year, we were also given the green light by the Western Australian Government to begin operations at our Mt Weld concentration plant following its successful construction. The first crushed ore was fed to the ball mill of our concentration plant on May 14, 2011.