Orion Minerals Ltd (ASX:ORN) has completed engineering studies on the ore processing plant design for its Prieska Copper-Zinc Project, South Africa, and quickly moved to secure specific mills needed to realise the identified improvements via an option agreement.
Orion managing director and chief executive officer Errol Smart said: “We are very pleased that we can now begin to lock in the anticipated project optimisations with associated positive CAPEX and OPEX savings.”
Plant optimisation studies
Smart said: “The successful metallurgical optimisation of the process flowsheet has culminated in securing the right to purchase two new mills which are available at a significant discount to mills which would otherwise have to be placed on order as a long-lead item.
“The plant optimisation studies progressed alongside studies on improved water treatment and optimisation of our mine-to-market schedule, all of which are now nearing completion.”
The 3,600-kilowatt mills consist of a 22-foot diameter by 26-foot long ball mill and a 16.5-foot diameter by 27-foot long semi-autogenous grinding (SAG) mill, complete with all motors, gearboxes, ancillary fittings, with associated commissioning spares.
Incorporating SAG milling
Securing these new mills facilitates the incorporation of SAG milling into the ore processing flowsheet, instead of the ball milling arrangement selected in the bankable feasibility study (BFS).
Smart added: “These optimisations all promise to deliver an uplift on the already excellent investment case for the Prieska Project.”
The revised configuration will allow significant operational flexibility and facilitate processing of Prieska ore at a rate of up to 20% above design throughput, allowing capacity for future expansion.
Reducing capital expenditure
The use of SAG milling also simplifies plant layout and operation, consequentially reducing upfront capital expenditure and the estimated operating cost by removing the requirement for multi-stage crushing and screening of rock ahead of milling.
Overall capital expenditure for the processing plant has been reduced by approximately $15 million from the total plant capital (originally estimated at $109 million) and the plant unit operating costs reduced by 5% from a base estimate of $16.10 per tonne.
These improvements will be incorporated into the optimised and updated BFS which is due in the second quarter 2020.