Overview
Fort a la Corne diamond project is located 60 km east of Prince Albert in northern Saskatchewan, Canada.
As early as 1940, diamonds were being reported in the Prince Albert area. Geophysical surveys that were completed in the 1960's identified possible diamond exploration targets. In 1988, Uranerz Exploration and Mining Limited discovered the first kimberlite in the region.
The project changed hands from De Beers and Cameco to Kensington, which in 2006 was acquired by Shore Gold. Later on Newmont acquired an interest in the project and the parties formed the FALC-JV.
The project encompasses the Star Kimberlite deposit and the Orion South Kimberlite deposit. Probable reserves as of January 31, 2010 were estimated at 279 Mt grading 12.47 carats per hundred tones (cpht) for 34.85 million carats.
The proposed Star and Orion South open pits will be conventional open pit mining operations that would produce 40,000 tpd of ore through a conventional truck and shovel operation.
The open pit, plant and infrastructure will be developed over a four year time line, and is scheduled to produce ore at a rate of 14.2 Mtpa for 20 years commencing in Q4, 2015.
The proposed 14.6 Mtpa capacity process facility incorporates autogenous milling, classification, dense media separation, diamond recovery and reject disposal.
Environmental studies confirmed that there are no material environmental issues that would prevent the Project from proceeding.
Location
The Star - Orion South Diamond Project (9,280 ha) is located in the Fort a la Corne (FALC) Provincial Forest, situated some 60 km east of Prince Albert, Saskatchewan. Good access is provided by paved highways, a grid gravel road system and an extensive network of forestry roads, passable by four-wheel drive and high clearance two-wheel drive vehicles all year round.
Saskatchewan is a Canadian prairie province first explored by Europeans in 1690 and settled in 1774. It became a province in 1905. Henry Kelsey, a fur trader and explorer, was the first European to set foot on the plains where he met First Nations and first hand witnessed the great buffalo herds of the Prairies.
Fort a la Corne was built in 1753 by Louise de la Corne and it was the farthest west French outpost in North America. In 1846, the Hudson's Bay Company built another fort close to the original location. The FALC Provincial Forest is a mixed-wood forest conservation area that encompasses both forts.
Nowadays Prince Albert, the 'great meeting place' in Cree language, boasts a population of 35,000 people. In 1866, the city was established as a mission post; in 1886 Saskatchewan's first recorded stagecoach robbery also took place near Prince Albert.
Diamonds were reported to have been found in 1948 in an area between Prince Albert and Flin Flon, by prospector Johnny Johnson. In 1961, Max Pollack claimed to have recovered 2 diamonds from gravel just west of Prince Albert.
The project area comprises rolling glacial topography that is drained by numerous small tributaries running south towards the Saskatchewan River. Elevation varies from 360 to 450 m above sea level. Much of the land surrounding the FALC Provincial Forest has been cleared for agriculture; the forest consists of jack pine, aspen, white and black spruce, poplar and tamarack.
The climate, in this region of Saskatchewan, ranges from warm, dry summers with temperatures typically averaging 23°C to cold, dry winters with temperatures averaging -11°C. Precipitation averages 405 mm annually.
Geology
The project lies near the northeastern edge of the Phanerozoic Interior Platform that extends from the Rocky Mountains in the west to the Precambrian Canadian Shield in the northeast. The Phanerozoic cover consists of basal Cambro-Devonian dolomitic carbonate rocks and clastic sedimentary rocks suceeded by Cretaceous shale and sandstone. The entire area is overlain by Quaternary glacial deposits ranging from 40 m in thickness close to the Saskatchewan River and up to 120 m in thickness elsewhere.
In the FALC area, a northwest-trending kimberlite province that is approximately 50 km long by 30 km wide has been identified. Sixty nine kimberlitic bodies have been discovered to date in the FALC kimberlite province.
The FALC kimberlites were emplaced into poorly consolidated Cretaceous clastic and marine sedimentary rocks. The kimberlite bodies themselves typically occur as stacked, subhorizontal lenses or shallow zones of crater facies kimberlite with footprints ranging up to 2,000 m wide and occur at depths ranging from 100 m to greater than 700 m.
Based on surface and underground core drilling and underground mapping data the Star and Orion South Kimberlite deposits contain two distinct types of kimberlite: eruptive kimberlite phases; and, kimberlitic sedimentary rocks.
The Star Kimberlite deposit is dominated by crater facies rocks, which include well-defined pyroclastic flows that radiate away from the crater. The Star Kimberlite deposit has a surface area totalling some 352 ha.
The Orion South Kimberlite deposit has a surface area totalling some 403 ha. Several conduits, feeding different units, have been identified on Orion South.
Large diameter drilling (1.20 m in diameter) was used to bulk sample kimberlite units as well as underground sampling by sinking a 250 m shaft and driving galleries and drilling stations at different levels.
Probable reserves as of January 31, 2010 were estimated at 279 Mt grading 12.47 cpht for 34.85 million carats.
Mining & Operation
The proposed Star and Orion South open pits will be conventional open pit mining operations. The company will operate and maintain the waste stripping in-pit crush and convey (IPCC) system, and mine the ore using its own equipment and labor force.
The Pre-Feasibility Study (PFS) includes a 20,000 tph capacity in-pit crush and convey system to strip overburden and waste rock which will be transported to a designated overburden and waste rock pile. An earthmoving contractor(s) will assist the company in stripping some of the surficial sand and clay materials.
The proposed IPCC system equipment includes four electric-powered shovels, four fully mobile sizers and in-pit transfer conveyors, an overland waste conveyor and stacking system at the overburden pile, and ancillary equipment such as blast hole drills and bulldozers.
Ore and associated waste rock will be mined by Shore using conventional hydraulic excavators and 136 t capacity trucks. The ore and waste rock will be hauled to in-pit ore and waste sizers, sized, and conveyed to the processing plant ore stockpile / overburden pile. It is projected that about 70% of the total ore and waste rock tonnage contained within the pit limits will need to be drilled-off and lightly blasted using ammonium nitrate and fuel oil (ANFO).
The company will mine ore at 40,000 tpd using its own equipment and operations and maintenance labour force. The ore will be hauled to an in-pit ore sizer, and then sized and conveyed to the processing plant ore stockpile.
The pit ramps were designed to be 32 m wide to accommodate two-way traffic for 6.7 m wide, 136 t capacity haulage trucks. Ramp gradients were designed at 10%.
The Star open pit contains an estimated 170.8 million diluted tonnes of ore in the Probable Mineral Reserve category and 504 Mbcm of waste material (1:3 strip ratio). The pit will be developed in five phases.
The Orion South open pit contains an estimated 108.6 million diluted tonnes of ore in the Probable Mineral Reserve category and 256 Mbcm of waste material (1:2.3 strip ratio). The pit will be developed in two phases.
The principal drivers of slope stability concerns relate to high ground water levels in shale and glacial sediments that will be slow to depressurize upon dewatering; and the existence of glacially sheared horizons. It is currently estimated that 22 dewatering wells will be required to depressurize the country rock around the Star open pit, and that an additional 22 dewatering wells will be required to depressurize the country rock around the Orion South open pit.
The deep well pumping rate is projected to range from 105,000 to 180,000 m3/d over the mine life. It is projected that the in-pit dewatering system (i.e. pit sumps and pumps) will typically pump up to about 30,000 m3/d, comprised of up to 10,000 m3/d from precipitation and groundwater seepage of between 10,000 m3/d to 20,000 m3/d.
Processing
The proposed 14.6 Mtpa capacity process facility incorporates autogenous milling, classification, dense media separation, diamond recovery and reject disposal.
Relative to Star ore, Orion South ore is characterized by lower comminution power requirements and lower mass yields from DMS processing, thus a plant designed for Star should have excess capacity when processing Orion South ore. The softer Orion South Kimberlite, however, exhibits the potential for increased materials handling problems due to its higher clay content. In this respect, the selection of autogenous mills for size reduction should minimize difficulties with clay within the plant.
Magnetic separation offers significant opportunity to reduce the quantity of DMS concentrate prior to the x-ray and grease concentration processes, due to the presence of
ilmenite and magnetite.
There will be three levels of security zones for the Project: Green; Blue; and Red. Green is low level with deer fencing and security gate; Blue is mid level with a chain link fence with security checking and monitoring along all entry and exit points; and Red is high level limited to the recovery plant.
The administration and change house building, primary substation, fuel and bulk lube storage and dispensing facilities, warehouse and parking lot will be situated in the Green zone. The maintenance and mine operating facilities, technical offices and process plant will be contained within the Blue security area. A Red zone secure helipad will be located adjacent to the Red zone process plant recovery building and will be used to transport recovered diamonds from the site by helicopter.
A diamond sorting facility will be constructed at an off-site location near Saskatoon. This building will measure about 37 m by 20 m and will be two stories high. Due to unique security requirements, this building will be a custom design.
Electrical power will be obtained from the provincial electrical utility SaskPower.
