Mount Weld mine

Mount Weld mine

Carbonatite with residual enrichment rare earth element deposit in Western Australia, Australia

Deposit type: Magmatic, Carbonatite with residual enrichment

REE minerals: monazite, churchite, xenotime,

Ore minerals: florencite, goyazite, cerianite, (Nb; Ta, F)

Gangue minerals: crandallite, apatite, pyrochlore, magnetite, ilmenite, quartz, calcite, dolomite

Host rock types: carbonatite

Average grade: 17% REO and yttrium, 7.9-11,7% REO

Status: REE-P resource

Company: Ashton Mining Ltd. (2000)

Resource estimates:

Indicated 15.4 Mt @ 11.2% REO + Y2O3 (5% cutoff) + 4.0 Mt @ 0.36% Y2O3

6.3 Mt @ 16.2% REO

15.2 Mt @ 11.2% REO (including Y)

6.3 Mt @ 17.2% REO (1990)

23.94 Mt@REO,0,5Mt@ Тr2O3; 1.5Mt@TiO2 , 0,400Mt@ Ta2O5 ; 0,11Mt @ ZrO2, Nb2O5

Mon has < 0.3% ThO2. Pilot plant at site in 1993.

Mount WeldREE deposit is a mountain and a mine site in Western Australia, located about 30 km south of Laverton and 120 km east of Leonora. It ranks as one of the richest major rare earth deposits in the world.

Carbonatite REE deposit with additional Nb, Ta, Zr, Ti contents ('Crown deposit' - apparently a separate part of the carbonatite).

Discovered in 1988; owned by Lynas Corp.

Rare earths are contained in secondary phosphates and aluminophosphates, presumably derived from weathering of the Proterozoic Mount Weld carbonatite, an intrusive pipe approximately three kilometers in diameter.

One of the references describes churchite as a fragile secondary mineral of microcrystalline acicular radiating crystals. It is found as void filling in crandallite group minerals, and as encrustations on limonite aggregates, weathered magnetite, on crandallite group grains, and sometimes as fine grained intergrowths with limonite.

The Mount Weld REE deposit representing the laterized cap of a large carbonatite shows generally high LREE/HREE ratios with locally enriched HREE and yttrium which are present in secondary phosphates such as crandallite and xenotime.

Physical concentration of the REE minerals is performed at Mount Weld. The run of mine material is subjected to crushing, grinding and flotation to produce a concentrate with a grade of 40% REO.

The separation into individual REO is carried out at Lynas Advanced Materials Plant in Malaysia.

References

1. https://en.wikipedia.org

2. https://en.wikipedia.org/wiki/Mount_Weld

3. https://www.lynascorp.com/Pages/Mt-Weld-Concentration-Plant.aspx

4. http://www.mindat.org/loc-146192.html

5. http://www.anzaplan.com/strategic-minerals-metals/rare-earth-minerals/rare-earth-minerals-processing/

@ Ph.D. Natalia Petrovskaya

June, 2016

nataliapetrovsky@gmail.com