Case Study Century Mine: Increased Zinc Recovery by Effective Graphite and Silicate Depression

The MMG Century mine produced around 500,000 tonnes of zinc concentrate per year in a combined lead and zinc flotation process with graphite and silica as the main gangue materials.

Declining grades are projected until mine closure, forcing the need to optimise grade and recovery. Pionera F-100 biopolymer was evaluated as an alternative depressant to dextrin. Lab tests and several plant trials showed that using Pionera F-100 lowered graphite and silica content as well as improved zinc grades in the concentrate.

This is an executive summary based on the scientific article “A Change in Graphite Depressant to Improve the Recovery of Zinc at MMG Century mine” by Wynn, R, Lauten, R A, Liang, H and Stoitis, N, 2014. In Proceedings 12th AusIMM Mill Operators’ Conference 2014, pp 179–186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Key takeaways:

• Increase in overall zinc recovery by reducing zinc content in final tails.
• The silicate content in the final zinc concentrate could be maintained below the required limits while zinc recovery increased.
• Pionera F-100 provided better graphite and silica depression compared to dextrin.

Analysis of final Zn cleaner concentrate.