Pilot Plant construction positions Browns Range to become a significant new source of high value dysprosium.
Rare Earths
Rare earths play an important and growing role in our modern society despite being a relatively unknown group of elements. Hybrid vehicles, energy efficient lighting and wind turbines are among the applications in which rare earths are critical.
Rare earths belong to the lanthanide series of elements with most only discovered in the last 120 years. Rare earths are more common than gold in the earth’s crust. The “rare” title comes from the limited economic abundance and from the complexity of extraction and processing.
Construction
The construction philosophy for Browns Range was a combination of in-situ and modular construction with materials and modules being delivered from China. Primero’s design and procurement teams were able to provide support to and keep the project on track by providing solutions to unexpected issues as they arose. Materials were provided to the construction team in a timely manner, ensuring commissioning of the critical circuits were compared on schedule.
Primero’s multi-disciplinary team constructed all civil, structural, mechanical, piping, electrical and instrumentation elements and commissioned both plants. This included the beneficiation plant (crushing and grinding, magnetic separation, and flotation circuits) and the hydrometallurgical plant (sulphation bake, water leaching, purification, and carbonate precipitation circuits).
Primero’s approach to self-performance meant that in-house resources were available at a moments notice to rapidly respond to emergent work and unplanned or out-of-scope events.
Process Description
From a process perspective, Browns Range was a $70M project comprising of a beneficiation and hydrometallurgical circuit. The beneficiation plant consists of a crushing circuit and a wet high-gradient magnetic separation and flotation plant.
ROM ore is crushed and ground to 63µm. Ground ore is then fed to a wet high-gradient magnetic separator to produce a magnetic concentrate rich in xenotime and iron oxide. Concentrate then passes through the float circuit to produce total rare earth oxide concentrate, which is thickened and filtered prior to being fed into the hydrometallurgical plant.
The hydrometallurgical plant uses sulphation baking, followed by water leach, purification, precipitation to produce a mixed RE carbonate concentrate. The concentrate is then to be washed, thickened, filtered and dried to produce a high-purity dysprosium-rich mixed rare earth carbonate.
Future State
At time of publication, Northern Minerals intend to optimise the hydromet process as a means of reducing downstream solvent extraction separation costs before scaling throughput of the beneficiation plant to 585ktpa as to provide the hydromet plant with 16,700tpa of feed concentrate.
