Rainbow Rare Earths Limited announced an update with regards to the pilot plant operations for the Phalaborwa rare earths development project in South Africa. The project's pilot plant incorporates the primary campaign, which processes the material to produce a mixed rare earth carbonate ("MREC"), based atthe Johannesburg facilities of the Council for Mineral Technology ("Mintek"), a global leader in mineral processing, extractive metallurgy, and related fields. The final separation stage pilot plant refines the material further into separated rare earth oxides; this work is ongoing in Florida, USA.

Excellent results have been achieved on the large scale, continuous pilot plant atMintek, serving toconfirm the basic process flowsheet originally set out in the PEA. The primary pilot plant campaign was extended to run for 70 days in order to take advantage of key optimisation opportunities that became evident during the operation. The key findings from the primary pilot plant campaign are: The overall recovery of rare earths was 66% versus 65% used in the PEA.

A leach temperature of 30oC was employed compared to 40oC set out in the PEA, resulting in a 50% reduction in the expected heating energy requirement. The first-stage impurity leach readily controlled the impurities to the desired level. Approximately 23% of the recovered rare earths reported to the impurity leach solution.

The subsequent rare earths leach has been reduced from three stages in the PEA to two stages. A continuous ion exchange ("CIX") pilot plant operation was conducted at Mintek to recover the rare earths in the impurity leach solution. This CIX pilot plant delivered excellent recovery, impurity rejection and rare earths upgrading with the resulting product being suitable for feed directly to the final continuous ion chromatography ("CIC") separation process.

Solid:liquid separation tests conducted on samples from the primary pilot plant operation yielded excellent thickening and filtration results, which allows for the removal of six CCL (Counter Current Leach) thickeners out of 12 from the circuit. Very positive results were achieved in a materials of construction study where a variety of potential acid-proof steels and alloys have been tested in static conditions and in the continuous primary pilot plant operation. These have shown that lower cost alloys out-perform the high cost Hastelloy materials assumed for the construction of the plant in the PEA.