Speaker Spotlight: Prof JJ Eksteen6 June 2019
In the build up to World Gold 2019 we will be interviewing the keynote speakers on some key issues related to the conference theme, Unlocking sustained value from gold deposits and what does the future hold for gold?
We recently interviewed interviewed Prof. JJ Eksteen. Professor Jacques Eksteen is the Chair for Extractive Metallurgy within the Western Australian School of Mines: Minerals, Energy & Chemical Engineering, at Curtin University. He is the Director of the Gold Technology Group and project manager of the AMIRA P420 projects (on Gold Processing Technology) since 2012.
Q. What do you see as the major technical innovations and technologies to unlock sustained value from gold deposits?
- Benign lixiviant systems have been in development that would allow in situ leaching, in-mine leaching and heap leaching.
- Coarse particle gangue rejection and comingling of rejects with final tails can improve tailings dam integrity.
- Filtered tailings implies that reagent recovery becomes feasible as long as contaminant accumulation is controlled. This allows for the use of more exotic lixiviants (than cyanide).
- Low grade, high sulfur gold concentrates remain problematic, particularly for where gold is in solid solution or in colloidal state.
Q. What does the future hold for gold?
A. While cyanide has many technical advantages, polymetallic ores, double refractory and preg-robbing ores and high sulfide ores significantly impacts the economics of cyanidation. More than cyanide toxicity, its tendency to form many by-products, many from which the cyanide cannot be recovered/regenerated, may play a determining role in its economics. Selective lixiviants with a lower propensity to form by-products exist and may be considered but need to be tailored to the ore, the leach technology applied and the downs stream recovery technologies.
Q. What message would you like to provide to the delegates – thus what do you hope will be the main message they will take away from your keynote presentation?
A. New lixiviant systems should be considered, but in an engineered and scientific approach. Hybrid or synergistic solvents can also be considered to lower cyanide demand while recovering the main lixiviant. Declining ore grades would require revisiting in-situ or in-mine leach approaches and optimising heap leaching with appropriate crushing. In all cases the use of a more benign lixiviant system will be of enormous benefit. The choice of oxidant and pH modifier will also have a large impact on the overall behaviour of the lixiviant system used.