The FalCon Project is located 65 km East of Prince Albert, Saskatchewan. The area, known as Fort a la Corne, hosts one of the most extensive kimberlite fields in the world.
Kimberlite Bulk Sample – Vertical Cutter Mining
Year: 2018 to Present
Client: Rio Tinto Exploration Canada Inc.
Project Scope Performed Under: Nuna Bauer Joint Venture
In partnership with Bauer Maschinen GmbH, Nuna has introduced to the mining industry the first cutter in the world capable of cutting to a depth of 250 metres in a commercial application. The Cutter Rig comprises a Bauer BC 50 vertical cutter mounted on a MC 128 duty-cycle crane.
Under contract to Rio Tinto Exploration Canada Inc., Nuna Bauer Joint Venture commenced vertical cutting services for a 3-phase kimberlite bulk sampling program comprising up to 30 holes (trenches) measuring each 3.2 m x 1.5 m with a maximum depth of 250 m. The project will be managed by Nuna; and with the exception of the Cutter Rig, all equipment will be operated by Nuna.
Site Access Road Scope: July – August 2018
Prior to mobilizing into the FalCon site for the kimberlite bulk sample program, significant upgrades were required to the 30 km site access road which included the installation of a bailey bridge. Nuna mobilized water trucks, haul trucks, excavator, dozer, loader, grader, tractor with wobblies, smooth drum packer, fuel truck, mechanic’s truck, pickups, and crew for the road upgrade scope. Work was carried out over a one-month period and comprised the installation of 250 linear metres of Neo-web reinforcement material, 3,075 linear metres of Combi-grid, and haul and placement of 2,430 m3 sand and 8,373 m3 gravel for road topping. Road grading, contouring and compacting completed the road activity.
Kimberlite Bulk Sample Scope: August 2018 – Present
Mobilization – Nuna Bauer Joint Venture mobilized a BC 50 vertical cutter, a MC 128 duty-cycle crane (together referred to as the Cutter Rig), BE-550 separation/ desanding plant, conveyors, HP-50 hose pump and a bentonite mixing plant from Germany. Support equipment for the erection of the Cutter Rig and the separation/desanding plant included a 120 tonne crane, a 70 tonne crane, loaders, telehandlers, and manlifts. Support equipment was mobilized from Edmonton and materials were sourced locally in the region.
Site Establishment – Nuna carried out the site establishment scope utilizing excavators, dozers, loaders, a packer, articulated trucks, a fuel/lube truck, and pickups. Site establishment scope included the consolidation and relocation of numerous piles of processed kimberlite prior to construction activities; construction of a 2,000 m3 capacity lined, double celled bentonite pond; and construction of various pads for the Cutter Rig, a BG 30 drill rig, the desanding plant, mechanic shop and the cement mixing station. A total of 1,100 m2 of Portafloor was placed under the desanding plant pad, mechanic shop and cement mixing station with rig matting being used to stabilize the pads around the trenches. 3,000 linear metres of 6” HDPE pipe was fused for water supply, bentonite movement and sample recovery. The sample recovery pipe had the internal bead removed after being fused for maximum retrieval of the product.
Cutter Rig Erection Scope – The erection of the Cutter Rig and desanding plant was carried out by Bauer Maschinen GmbH crew from Germany and aided by Nuna along with local subcontractors (Prairie Crane, Meridian Survey, Green’s Graveling, Flyer Electric, and Norseman). Support equipment included a 120 tonne crane, a 70 tonne crane, loaders, telehandlers, and manlifts.
Trench Cement Casing Scope – The unconsolidated subsurface soil conditions on site required the pour of a 7-panel rectangular cement casing (2 MPa) – or foundation – to a depth of approximately 21 metres prior to the BC 50 vertical cutter excavation of the trench. Utilizing a BG 30 rig with a cutter soil mixing (CSM) attachment, cement is mixed with the in-situ subsurface materials to create the panels. Panel scope is under Bauer Foundations Canada. Nuna provided full time support including excavators, telehandlers and a pump crew.
Trench & Bagging Scope – Trench excavation and operation of the cement mixing plant, will be performed by Nuna. Each trench will be excavated to a 6 metre depth. This is to ensure that both pumps of the BC 50 are fully submerged in the bentonite slurry prior to commencement of cutting.
A bentonite pond bubbler system will keep the bentonite moving to prevent consolidation. Bentonite will be mixed using a big bag station that is augured into the SKC-60-K mixing plant. This material will be discharged into the “clean” cell of the pond and pumped into the “production” cell of the pond which is then transferred to the desanding plant and sent to the trench.
Kimberlite Bulk Sample Sequence – The Cutter Rig was specifically designed to reach a maximum depth of approximately 250 metres. The first approximate 110 to 120 meters of a trench are considered overburden or waste material with the remaining 130 to 140 meters being the sample zone. The material will be pumped from the Cutter Rig to the desanding plant. While the overburden material is being trenched, the desanding plant conveyors will move the “waste” which is collected and trucked to a stockpile location in preparation for backfilling. When the sample horizon is reached, the conveyors will switch directions and samples will be taken every 10 metres. These samples will be washed in the “big bag” station on the desanding plant and placed into mega bags to be processed at the RTEC DMS plant. Two 930 loaders will support the bagging process full time. The product lines from the Cutter Rig will be pigged to ensure that the sample is fully recovered. After the desired depth has been reached in the trench and the sample has been recovered, the Cutter Rig will pull out and move to the next location. All feed and return lines will be moved with the unit. The final step in the trenching process requires backfilling. The material that will be put back in the trench will be “like for like”; meaning that the processed sample will be filled first, followed by a bentonite chip seal of 10 meters (to ensure that there is a distinction between the sample and overburden horizons) and finally overburden. This will be done using a large funnel that is placed with a loader. The bentonite slurry that is in the trench will be pumped with an HP-50 to a smaller BE-100 desander and recirculated back to the “production” cell of the bentonite pond to be used on the next trench.