New Gold’s New Afton gold-copper project west of Kamloops in British Columbia, Canada has four general mining zones, located beneath and to the west of the Afton open pit. Current production is coming from the B1 and B2 zones (Lift 1) where there are two panel caves (west and east) in operation. Production commenced in the west panel and is now nearing completion with the last planned West Cave production in February 2021. The east panel is separated from the west panel by a 50 m to 60 m thick waste zone.
A production area located beneath the East Cave has been identified for SLC extraction of the remaining cave material beneath the East Cave. The East Cave is to continue in production until mid 2021 with East Cave Recovery levels continuing until late in 2021. The B3 Block is located 160 m below and immediately to the west of Lift 1. Ore from B3 will be hauled by truck to the existing gyratory crusher. Development of the B3 undercut and extraction levels is currently underway. Production is scheduled to commence in the B3-zone with the first of 66 drawbells in January 2021 and production will continue until late 2024. The C-zone block cave zone is located approximately 550 m below Lift 1. Development towards the C-zone is underway with production planned to commence with the first of 143 planned drawbells in July 2023.
The Lift 1 haulage level consists of four main legs below the extraction level connecting to the ore passes. LHDs load from the ore passes and fill 45 t haul trucks which haul the material to a centralised crusher. From the crusher, the material is conveyed to surface onto an ore feed stockpile.
The B3 block cave will produce from 2021-2024 and will employ straight-through drawpoints, where ore will be loaded by LHDs to be dumped into ore passes to the haulage level. Automatic truck loading chutes will fill autonomous haul trucks, which will transport the ore to chutes leading to the existing Lift 1 crusher.
The C-zone block cave will be producing from 2023-2029. Ore segregation is planned to improve mill grades while a second crusher and underground conveyor system extension for materials handling is to be installed. LHDs will haul the ore from the ore passes to a new underground primary gyratory crusher to be installed for the C-zone. Haul trucks have been eliminated from the material handling flow on the C-zone level. The ore will then be conveyed from the crusher to a junction with the existing conveyor for movement to surface. Waste from the C-zone will be handled in the same manner.
Due to its depth a major focus for the C-zone block cave is electrification, due to its potential to reduce ventilation requirements and operating costs. Currently there are three planned trials – a battery electric Toyota trial, a Sandvik battery bolter field trial and a MacLean BEV trial. The MacLean BEV is a Boom Truck model (BT3-EV), which is already being put through its ramp-run trial paces, tramming up a 4.5 km ramp, with a 17% average incline, max speed of 14 km/h, and 53% battery draw down. No details have been given for the Sandvik machine though the company has just announced it will launch the DS412iE battery rock bolter in 2021. This is a tethered machine which uses a battery for tramming and the cable while drilling and is basically an upgrade on its existing Sandvik DS411. It can handle a wide range of bolt types and lengths, including a combination of automatic cement mixer and automatic resin injection on the same bolter.
Automation wise, while no information has been given on the planned autonomous trucks, New Afton already has two Sandvik LH410 LHDs capable of teleremote operation and has the mine permit amendment for automated use of the units. The LHDs provide increased utilisation as they can be operated from a control room on surface and reduce operator exposure to potential mudrush conditions. The rest of the LHD fleet includes 10 Cat R1600G and 4 R2900G machines, with 7 Cat AD45 trucks.
