Simply explained, our current production concept consists of five operational areas. Each area progressively eliminates waste sands (gangue) and concentrates rare earth minerals, primarily monazite and xenotime. Other industrial minerals, such as zircon, ilmenite and rutile are also concentrated.
The operation begins with the mining cycle. Using a large loader, sand is loaded into a hopper/feeder and conveyed to a "grizzly" screen. The "grizzly" is used to remove over-size rocks (approximately +50mm in size). The under-size is retained, mixed with water and pumped as a slurry, to the pre-concentration screening plant. Most the valuable minerals are contained in sands less than 600 micron (-0.6mm) in size. A combination of vibrating screens and de-sliming hydro-cyclones eliminate coarse sand and ultra-fine material, which is de-watered and returned to the pit via conveyor. The retained sand slurry is pumped to a wet concentration plant. This plant consists of a series of spiral separators and pumps to progressively concentrate the minerals. At this point, about 6.5% of the sand mined is retained as a concentrate. This concentrate is pumped several kilometers to a fixed wet magnetic separator plant, which is used to remove ilmenite and unwanted iron from the concentrate.
A dry separation plant is used to further separate the minerals. This plant uses charged separators (electrostatic separators) and strong magnets to separate rare earth and industrial minerals. Rare earth mineral concentrate is transported to the refinery for "cracking" and chemical treatment. The refinery produces a variety of mixed rare earth oxides / carbonates of high purity. These will be packed for road transport via containers. The diagram below shows the processes and throughput.
Water conservation is a significant operational consideration. Recycled water is used for each step. A central water treatment facility will remove fine sediment and return water to the various processes. Deep basin water will be used to top-up any water losses. This water will be pumped from a distant bore field (within 20km).
An on-site refinery will chemically extract valuable minerals and stable waste residues. These residues will be recombined with the vast quantity of rejected sand from the pre-concentration and wet-concentration processes and returned to the mining area. The co-disposal will ensure that mineral derivatives and stable complexes of concentrations that are as benign as the original in-situ material.
The proposed operational concept is illustrated below:
More detail of the proposed process flowsheet is illustrated below.
Mineral Processing Flowchart
Mineral Technologies Aust.
REO to refinery