Rainbow Rare Earths laboratory test work and the trade-off studies that are being evaluated to further optimise capital and operating costs for the Phalaborwa project is making significant progress.

The Rainbow laboratory in Johannesburg has now been in operation for approximately three months and is equipped with state-of-the-art technology that allows for the performance of leaching, ion exchange, precipitation and separation test work across the full Phalaborwa processing flowsheet.

Most importantly, the laboratory features a cutting-edge ICP-MS (Inductively Coupled Plasma – Mass Spectrometer) for analysis of samples taken from test work, which enables the immediate assay of grades ranging from low parts per billion to high purity to be reported internally. This level of accuracy is vital for the evaluation of the Company’s separation test work. The laboratory is equipped to automate test work where possible to ensure accurate and rapid results.

Also Read: Rainbow Rare Earths achieves high-quality production at Phalaborwa

Turnaround times for these tests are therefore considerably faster than the typical 72 hours to three weeks experienced when using external providers. This rapid turnaround ensures that test work can be continuously progressed in a targeted and informed manner based on previous test results.

CEO George Bennett said “We are very proud of the laboratory we have built in Johannesburg which incorporates state-of-the-art equipment that enables the performance of test work across the full Phalaborwa processing flow sheet.  Establishing our own in-house facility allows for the execution and analysis of this critical optimisation and separation test work at an accelerated rate and at a much lower cost than using third party facilities. We have identified the key priority focus areas for the test work, and I look forward to announcing the results of the various stages of the ongoing programme as these become available.

“This optimisation work will further enhance the economic resilience of a project that is already deemed to be one of the highest margin REE projects in development today, according to Argus Media.  At a time when the world urgently needs diversified REE supply, Phalaborwa is poised to be a strategic source of all four magnet rare earths.”, he added.

By carrying out the test and assay work at in-house facilities, the company has delivered significant savings compared to using third party providers and expects to pay back the modest cost of building the laboratory within a few months.

Following the interim study released in December 2024, test work and associated work has been focused on:

• Undertaking trade-off studies for the leaching circuit to minimise both operating and capital costs
• Maximising rare earth recovery and impurity rejection via CIX
• Definition of the optimal path to purification of the mixed rare earth feed ahead of final separation

Further information on these key work programmes is as follows: 

1.    Trade-off studies to optimise the leach circuit

 The leach circuit is estimated to represent approximately 80% of the Phalaborwa flowsheet and therefore offers the best opportunities for cost optimisation. While Phalaborwa’s capital and operating costs are already considerably lower than the majority of the rare earth peer group, the work that was done during the project’s Interim Study identified areas where further test work and trade-off studies have potential to reduce costs, making Phalaborwa even more resilient in terms of its economics. 

The key optimisation opportunities identified, which are expected to deliver savings in power, reagent, labour and capital costs, are:

• Replacing the three-stage 30˚c leaching circuit with a two-stage higher temperature leach circuit with reduced residence times
• Mechanical vs hydraulic reclamation of the phosphogypsum
• On-site sulphuric acid plant vs acid supplied from a third party
• The cost and supply resilience of third-party green energy vs Eskom power supply

Rainbow Rare Earths says it intends to use the results of the trade-off studies to provide the market with an update as to the potential impact on capital and operating costs for the project ahead of the DFS publication.

ALSO READ: Rainbow Rare Earths achieves milestone in rare earth oxide separation progress

2.    Maximising rare earth recovery and impurity rejection

The company says the extensive piloting work carried out to date has established that the production of a high grade, low impurity feed stream to the separation process is key to achieving separated rare earth oxides of the desired purity level.

The development of the leaching process has successfully managed impurity build-up in the leach solution to prevent the impact of impurities on the extraction of rare earths from the phosphogypsum. The company says it has seen the benefits in using CIX as the primary process to recover the rare earths from the leach solution, which is expected to successfully reduce impurities in an efficient and cost-effective way, producing a low impurity feed stream for separation.

A number of resins and eluants have been tested at bench scale to select the configurations of the primary IX rare earth recovery circuit to be used for pilot scale test work.

3.    Definition of the optimal path to final separation

Early testing is underway looking at key impurity levels from the primary CIX and proven rejection techniques ahead of separation. For the separation test work it is important that the leaching and recovery options are finalised to ensure a representative feed. Ahead of the final purification results, early ion chromatography separation tests are underway to establish rare earth performance under various configurations. These tests are expected to accelerate the development of the final recipe once the purification steps are complete.