Hi there, I didn't know the answer to your query so Chris provided the below reply this morning.
These are great questions; I’ll answer what I can and add a bit more info; The
particle (Particle and Density being the operative words here) ore sorters through
Density is very powerful and as you point out a very cheap pre-treatment concentration process in the flowsheet or there is a strong argument that they are and can be used for grade control (depends who you ask) off the shelf technology readily used around the world.
One main point I want to flag is the
Particle X-ray sorters work exceptionally well on the Korbel material as all the test work has been done on
density ie; the sheeted veins where the gold sits is about 4-5 S.G whereas the country rock is at about 2 S.G and can pick it out exceptionally well as per images below. (a lot of people get confused with
optical ore sorting in Archean type mineralogy in the eastern gold fields where once crushed the
colour is very hard for the machine to pick up)
To answer your questions, yes, the current level of ore sorters is matched with what is required with the optimum 6mtpa plant for a capex the company is comfortable with at this time but can increase the number of ore sorters units as the years go by as they are modular with increasing the plant size through cashflow now that we have that 11 month payback (Same growth sequence as ridgeway was for the Cadia mine – yes that’s the plan and potential, Estelle to be a tier 1 Cadia type gold producer in time). In terms of dialling up the sorters to get higher grade, you get gold loss in the rejected material early in the comminution process which obviously we want to get every spec of gold we can get - hence we will be focussing on fines by pass test work (a lot of trade offs to go to find the optimum)
But in saying that you are also 100% correct, the machines give that flexibility to go higher grade depending on the gold price and we can go back for the rejected material later to process.
