Aim-listed Premier African Minerals has provided an update on completion of the initial flotation plant test run at the Zulu lithium and tantalum project, in Zimbabwe, following the installation of the spodumene float section inserts.

As previously announced, the initial plant test run started on July 6.

Following the installation of the cleaner cell inserts, the plant was restarted on July 6.

Before any comprehensive assessment could be made, it was necessary for the plant to achieve a state of stability and constant running. Owing to the long standing time prior to restarting the plant, it took longer than anticipated to achieve a constant running state, which was finally achieved towards the end of the initial test run, Premier explains. 

The inserts have now shown that they reduce the retention time of concentrates in the cleaner section of the original float plant as originally contemplated by the original-equipment manufacturer (OEM).

During this test run, there were “encouraging signs”, Premier highlights, including an observed improvement in concentrate grade with results exceeding the target grade of 5% in the final cleaner cell prior to being pumped to the filter press (bagging plant).

This has not been matched, for now, by a meaningful improvement in recoveries, with excess lithium superoxide present in the tailings which are then recirculated to the flotation circuit.

Premier’s priority is to achieve a commercially saleable grade and then optimise for recovery and in that context, the company says it is “encouraged” with the early indications.

However, to improve the recovery rate and further ongoing optimisation, the initial plant test run has stopped and the OEM for the float plant will assume full operational control of the plant for the week starting July 21.

During this, the plant test run will restart with an objective to achieve a sustained steady state of operation, which is expected to provide a clearer basis for evaluating flotation plants' performance and identifying any opportunities for optimisation that would contribute to improved recoveries to optimise those elements of the plant.

To this extent, ongoing maintenance and checks of the operation of each of the plant components continue, with the intention to have the plant restarted as part of the OEM test run next week.

“As much as Premier is pleased with the initial progress to date, we were frustrated with the time needed to get the plant into a constant running state, although, as reminded by our OEM, this not a simple plant and maintaining target operating parameters requires time and patience,” CEO George Roach says.

“We remain deeply appreciative of the ongoing support we have from our contractors, staff and shareholders. Civil construction for the alternative spodumene float section is now almost complete, which is planned to provide both a fallback option if needed and also the ability to expand Zulu existing process capacity of spodumene concentrate,” he adds.