This report details the proposed processing route and design criteria for the KZK project to treat run-of-mine ore at a nominal rate of 2.0 Mtpa producing separate copper, lead and zinc concentrates.
Report context
This technical report, dated 2017, presents the recovery methods and process plant design for the KZK project. The report was prepared for BMC Minerals (No. 1) Limited under Report Number R103.2017. The process plant and associated service facilities are designed to process run-of-mine (ROM) ore at a nominal rate of 2.0 Mtpa to produce separate copper, lead and zinc concentrates and tailings.
Processing route
Overview
The proposed process consists of crushing and grinding of the ore, separate sequential pre-float, rougher and cleaner flotation of copper, lead and zinc, and regrind of copper, lead and zinc rougher concentrates. Concentrates will be thickened, filtered and stockpiled on site prior to being loaded onto trucks for transport to third party smelters. Flotation tailings will be dewatered by thickening and vacuum filtration before the tailings are transported either for disposal at the Class A Waste Storage Facility or combined with cement to produce underground backfill paste.
Gravity circuit
Allowances for gravity gold and silver recovery have not been included in recovery estimates for the purposes of this technical report, as additional work is required to improve circuit recovery predictions. A gravity circuit is shown on the process flowsheet due to the expectation that it will be shown to be economically viable in the future.
Crushing
Ore will be transported from the open pit and underground mines to the ROM pad stockpiles by mine haul trucks. ROM ore will be reclaimed from the stockpiles by front-end loader (FEL) and fed into a 100 t ROM bin that will provide 20 minutes live capacity. ROM ore will be withdrawn from the bin by an apron feeder.
The primary crusher will be a 1,400 x 1,070 mm open circuit jaw crusher capable of handling an ore top size of 900 mm. The primary crusher will have a closed side setting (CSS) of 125 mm and reduce material to nominally P80 90 mm based on the soft nature of the ore. The primary crusher will have an availability of 75% based on similar installations, giving a nominal crushing rate of 304 tph.
A dust suppression system with baghouse filter will be installed in the crushing system and discharge conveying system to minimize dust. Spray nozzles will also be used around the ROM bin and transfer points.
The primary crusher will discharge onto a conveyor then onto a stockpile feed conveyor. Tramp material (waste metal that has entered the ore stream, such as bucket teeth and bolts) will be removed from the crushed ore stream at the conveyor transfer point between the primary crusher discharge conveyor and the crushed ore stockpile feed conveyor by a fixed self-cleaning magnet. Allowance has been made for a diverter gate at the conveyor transfer point to allow for material to be diverted to a future heavy media separation (HMS) plant.
The crushed ore stockpile will provide a minimum of 3,000 t of live storage with two reclaim apron feeders located in an under-pile tunnel. The stockpile will provide 12 hours storage capacity at the nominal SAG mill feed rate. Each apron feeder will provide the nominal SAG mill feed rate of 245 tph. The stockpile will be conical in shape and covered to minimize dust generation.
Flotation and concentrates
The proposed flowsheet includes separate sequential pre-float, rougher and cleaner flotation of copper, lead and zinc, and regrind of copper, lead and zinc rougher concentrates.
Concentrate grades and recoveries
Average concentrate grades over the life of the mine are predicted to be 22.8% copper, 56.0% lead and 51.5% zinc for copper, lead and zinc concentrates respectively.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Nominal processing rate | 2.0 Mtpa | Design |
| Primary crusher type | 1,400 x 1,070 mm open circuit jaw crusher | Design |
| Primary crusher closed side setting | 125 mm | Design |
| Primary crusher product size (nominal) | P80 90 mm | Design |
| Primary crusher availability | 75% | Design (based on similar installations) |
| Primary crusher nominal crushing rate | 304 tph | Design |
| Crushed ore stockpile live capacity | Minimum 3,000 t | Design |
| Crushed ore stockpile storage capacity | 12 hours at nominal SAG mill feed rate | Design |
| Nominal SAG mill feed rate | 245 tph | Design |
| Average copper concentrate grade | 22.8% Cu | Design (predicted life of mine) |
| Average lead concentrate grade | 56.0% Pb | Design (predicted life of mine) |
| Average zinc concentrate grade | 51.5% Zn | Design (predicted life of mine) |
| Copper concentrate copper recovery | 81.5% | Design (predicted life of mine average) |
| Copper concentrate gold recovery | 41.9% | Design (predicted life of mine average) |
| Copper concentrate silver recovery | 42.6% | Design (predicted life of mine average) |
| Lead concentrate lead recovery | 58.7% | Design (predicted life of mine average) |
| Lead concentrate gold recovery | 18.4% | Design (predicted life of mine average) |
| Lead concentrate silver recovery | 25.1% | Design (predicted life of mine average) |
| Zinc concentrate zinc recovery | 85.9% | Design (predicted life of mine average) |
| Zinc concentrate gold recovery | 8.7% | Design (predicted life of mine average) |
| Zinc concentrate silver recovery | 14.6% | Design (predicted life of mine average) |
Project website: https://bmcminerals.com/
Technical qualifications
The technical report notes that allowances for gravity gold and silver recovery have not been included in recovery estimates as additional work is required to improve circuit recovery predictions. The process design criteria were derived from the results of the metallurgical testwork program. The proposed process plant design and control are based on unit operations that are well proven in the base metals industry.
Source: KZK Project, NI 43-101 Technical Report, Report Number R103.2017, 2017, Section 17 Recovery Methods.
