OUR TRACK RECORD
ST BARBARA - SIMBERI SULPHIDES & LEONORA PROVINCE PROJECTS
The Details
TIMEFRAME: 2022 - 2025
CLIENT: St Barbara
LOCATION: Western Australia | Papua New Guinea
COMMODITY: Gold
SERVICES: Metallurgical Testwork Management | Mineral Processing Plant Design | Owners Representative
CHALLENGES
Highly variable refractory gold ore
CONTRIBUTIONS
New program of >400 tests
Concept & PFS studies
OUTCOMES
6-7% recovery increase.
Optimised flowsheet with saleable concentrate.
Simberi Sulphides Project
St Barbara’s Simberi gold operation in PNG commenced operation in 2008, treating oxide and transitional ores. By 2022, processing of the underlying refractory sulphide ores had been subject to a number of feasibility studies looking at how to progress processing of the refractory sulphide ore, but no investment decision on the project had been made. Following the sale of the Leonora Operations in 2023, Chemech was engaged by St Barbara to undertake a desktop review of the previous testwork program and studies with an eye to identifying opportunities further refine the project.
Chemech’s initial independent review of the historical work highlighted a number of significant risks and opportunities with the proposed sulphides flowsheet and the testwork supporting it. St Barbara therefore engaged Chemech to complete a scoping study investigating alternative flowsheets, while developing a new metallurgical sampling and testwork program in parallel.
The scoping study included six alternate flowsheet and throughput options, and Chemech developed the process design for Class 5 capital cost estimation of each option. The outcome of the study allowed St Barbara to select the optimal throughput and identify two flowsheets for the new testwork program.
In 2023, St Barbara engaged Chemech to manage their new metallurgical testwork program which included sample selection, technical oversight and direction, interpretation of results, and provision of process design recommendations. The program was extensive, testing 29 composites from 3 highly-variable and metallurgically complex orebodies. Over 400 individual tests were conducted with comprehensive assaying, diagnostic testing and specific mineralogical assessments. The result was a substantial improvement in the metallurgical understanding of the sulphide ores as well as:
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Selection of the most economically viable flowsheet capable of high gold recoveries (>90%).
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An improvement in overall gold recovery of 6-7% over historical testwork programs.
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Delivery of a suitably optimised recovery flowsheet and testwork conditions to allow confident development of the plant process design.
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Quantitative understanding of the metallurgical response to the highly variable orebodies.
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Significant de-risking of historical sample representivity and metallurgical response issues.
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Suitable testing to confirm the statutory compliance necessary for the deep-sea tailings placement (DSTP) system.
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Final concentrate characterisation to ensure its suitability for shipping and sale.
Chemech showed a very high-level of commitment and technical proficiency in managing our 2024 metallurgical testwork program, which included sample selection, technical oversight and direction, interpretation of results, and process design documentation. The end result of Chemech's work was optimisation of our process design and testwork outcomes that significantly reduced our processing risks relating to recovery and concentrate quality as well as delivering greater project value from improved gold recovery.
- Brett Ascott - St Barbara Executive General Manager Projects and Technical Support
Leonora Province Project
In 2022, St Barbara were completing study work on their Leonora Province Plan (LPP), which included throughput upgrades to their Gwalia processing plant and a new 2.1Mt/a refractory ore treatment plant. St Barbara engaged Chemech as Owner's Representatives to provide metallurgical and technical support to their LPP Project Team.
Chemech initially provided technical support to the metallurgical testwork programs for free milling and refractory ores. This included ore characterisation and variability testwork as well as specific testwork to generate process data for the Albion process chosen to treat the refractory ores. Chemech then provided a review of the Albion processing plant capital cost estimate that was generated for the LPP feasibility study.