Mining & Trade News

By Marcel Chimwala

ASX-listed Sovereign Metals has announced that the excavation of a test pit, using dry mining methods, has been completed successfully. The excavation is part of the ongoing Pilot Mining and Land Rehabilitation Program at the Company’s Kasiya Rutile-Graphite Project in Lilongwe, Malawi.

Sovereign Metals MD Frank Eagar explains that the completion of this phase of the Pilot Program confirms that Kasiya can be efficiently mined using standard mobile excavators and trucks, further demonstrating operational alternatives as part of the ongoing Pre-Feasibility Optimisation Study.

The test pit has been excavated as planned with all work on schedule to a depth of 20 metres, handling approximately 170,000 bench cubic metres. Steady-state operations envisage 24 million tonnes of material being mined annually. The excavatedmaterial is being stockpiled on site and as part of the next phase of testwork will be separated into various size fractions through the use of cyclones. Once separated into different size fractions, the material will be backfilled into the test pit for materials deposition testwork.

For the test pit, the excavation was completed with a dry mining fleet consisting of four excavators, 20 trucks and a support fleet including two bulldozers and a motor grader.

Eagar says: “Completion of the test pit at this scale marks a significant achievement. The mining, hydrology and geotechnical data collected throughout is invaluable in our understanding of the orebody and the simplicity of a potential dry-mining operation at Kasiya. We now look forward to the next steps of the pilot phase including the hydraulic mining trial, cyclone separation of ore, backfilling of test pits and soil rehabilitation.”

Eagar explains that the saprolite-hosted mineralisation at Kasiya is largely homogenous and has relatively consistent physical properties throughout the 1.8 billion tonnes Mineral Resource Estimate.

“Data collected from the pilot phase confirmed that no drilling, blasting, crushing, grinding or milling will be required prior to stockpiling material for processing into rutile and graphite products; an indication of potentially lower mining costs and a lower carbon footprint comparable to hard rock deposits,” he says.

Eagar reports that hydraulic mining trials will begin in coming weeks. A temporary water storage pond has been constructed and sealed using natural clay from excavated material, minimising the use of conventional plastic lining. The pond is being filled by eight boreholes delivering water to site and is nearing its capacity of six million litres. Water from the storage pond will initially be used for the hydraulic mining stage.

He says the main pit will be backfilled with dry material, while material from hydraulic mining will be used to fill rehabilitation pits as part of the rehabilitation phase of the trial.

Background to the Pilot Phase

The Pilot Phase is a critical part of Kasiya’s optimisation study and ongoing feasibility work; empirical data generated from the Pilot Phase will determine optimal project excavation, material handling, processing, backfilling and rehabilitation approaches. The Pilot Phase is being undertaken on a 9.9-hectare site and includes the following activities:

1. Test Pit: A test pit of 120m by 110m excavated to a depth of 20m, allowing optimisation of hydraulic and dry mining excavation methods.

2. Stockpiles: The excavated material will be temporarily stored in 4 stockpiles, namely all dry mining material, wet slimes (in a pond) and two sizes of sand fractions from the hydraulic mining.

3. Backfilling and Grading: The material will be placed back into the pit, and all areas will be graded.

4. Rehabilitation Demonstration: Sovereign will construct eight small rehabilitation demonstration pits covering a combined area of 100m by 130m. These will be used for water storage, excavated material storage, and demonstration of multiple land rehabilitation approaches.

5. Temporary Laydown Areas: Four areas will be used as temporary laydown areas, offices, and associated infrastructure.

6. Communication: The Pilot Phase will be an educational opportunity for Project stakeholders. Sovereign will undertake a series of stakeholder visits and consultations for this purpose.

Eagar explains: “Sovereign’s objective is to restore land after mining to conditions that achieve the same or better agricultural yields than existing land uses and crop yields. The Pilot Phase will demonstrate to local communities the successful rehabilitation of land for agricultural use post-mining; land rehabilitation will form an integral component of the ongoing optimisation study.”

“Results of this Pilot Program will also allow Sovereign to determine optimal excavation and backfill approaches, providing critical information for the upcoming Definitive Feasibility Study.”

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