Magnetite Mines Ltd (ASX:MGT) welcomes the completion of a peer review of the process plant for the Razorback Iron Ore Project in South Australia with outcomes confirming the feasibility of the Hatch-engineered flowsheet and plant design.
The company’s objective is to produce high-grade magnetite concentrate with grades above 67.5% iron, with the process flowsheet designed to process iron ores for minimum operating cost.
Independent assessment
An independent technical team completed the assessment across four key areas - process flowsheet; equipment selection, including crushing, HPGR, milling, dewatering and filtration; materials handling aspects; and metallurgical results.
The review confirmed the feasibility of the current process flowsheet and plant design and highlighted economies of scale benefits that may be realised with increased production capacity, in line with the decision to increase the scale of Stage 1 production capacity to a minimum of 5 million tonnes per annum.
Schematic flowsheet for the Razorback Iron Project.
In particular, scale-up opportunities were identified in the areas of stockpile reclaim and primary grinding for capacities of 5 million tonnes and higher.
The review was completed by independent industry specialists with extensive magnetite processing experience.
An accompanying metallurgical test-work suite was also conducted to de-risk the flowsheet at every stage of processing.
Optimisation studies
The review’s findings support the scope of the company’s processing-focused optimisation studies.
These studies also reference the extensive metallurgical test-work and engineering design studies already complete. Results are due in the first quarter of 2023.
Key features of the process plant design and flowsheet are expected to carry over into scaled-up designs, including:
Process plant feed flexibility - the process plant has been designed to cope with a wide range of head grade and mass recovery parameters at nominal throughput rates, to accommodate anticipated ore variability from the mine during operations.
This feature allows the process plant to maintain throughput consistency and yield over the life of mine, addressing many of the orebody variability issues seen in West Australian magnetite processing operations.
Concentrate specification flexibility - The process plant design is centred on the Razorback ore’s ability to produce high-grade concentrates with a minimum 67.5% iron concentrate specification.
Metallurgical test-work results have demonstrated that higher-grade outputs are achievable for some areas of the ore body. This feature has been adapted into the design of the process flowsheet and plant design whereby operation can be adjusted with respect to product quality in response to market conditions or customer preference, without capital-intensive plant modifications.
Modular construction - The process plant design centres around single production trains of nominal 2.5 million tonnes per annum capacity, with expansion to higher capacities largely entailing duplication.
The current optimisation studies are assessing economies of scale benefits that apply to increasing plant modules. For example, a single large primary crusher may service two production lines, decreasing capital and operating costs.
Early-stage rejection of low-grade material - The process plant has been designed to reject low-grade material early in the flow sheet, taking advantage of high-level confidence in the metallurgical and comminution performance of the ore.
Early-stage rejection of gangue or low-grade material significantly reduces the downstream plant size for a given output capacity, a key capital and operating cost benefit.
Additionally, the production of wet tailings is significantly reduced, a further benefit in terms of capital and operating cost, as well as improved environmental and safety outcomes.