Renard Diamond Project, Canada

The Renard Diamond project is located in east central Quebec, Canada, within the Foxtrot property. It is owned jointly by Stornoway Diamond and SOQUEM Inc.

The project covers 315,323 acres and includes a newly discovered field of kimberlitic intrusions referred to as the Renard cluster. Four pipes from the cluster namely Renard 2, 3, 4 and 9 have been included in the updated Preliminary Economic Assessment.

Production at the mine is scheduled to begin by the end of 2013. It is estimated to produce 30m carats of diamonds over its life span of 25 years. An investment of C$511m is estimated to be required for the development of the mine.

A feasibility study by SNC-Lavalin, began in July 2010. It is scheduled for completion in the third quarter of 2011.

Reserves

The mine contains 26mt indicated and 17mt inferred resources. Indicated resources at Renard 2, 3 and 4 have been estimated at 17.4mt, 1.7mt and 7.3mt.

Inferred resources at Renard 2, 3, 4 and 9 are 5.3mt, 0.1mt, 4.5mt and 5.7mt respectively. Inferred resources also include 1.7Mt at Lynx and 0.17Mt at Hibou.

Geology

The deposit lies within the south-eastern section of the Superior Craton, a combination of small continental fragments of oceanic plates from the Meso-Archean and Neo-archean age.

Five episodes of kimberlitic volcanism have led to the formation of five fields, Témiscamingue, Desmaraisville, Otish, Wemindji, and Torngat, from south to north.

The Renard cluster is associated with the Otish kimberlitic volcanic event. Nine bodies of kimberlite have been identified over an area of 2km² within the cluster. The bodies Renard 1 to 10 are spaced at a distance of 50m to 500m. The Renard pipes are egg-shaped, irregular with areas of 0.3ha to 1.5ha.

The pipes contain root zone to lower diatreme facies rocks. The internal geology of the rocks is complex and is characterised by massive volcaniclastic kimberlite, categorised as tuffisitic kimberlitic breccia (TKB).

By volume the TKB includes 15% to 90% fresh to moderately transformed granitoid country rock clasts in a matrix that is characterised by serpentinised olivine macrocrysts, carbonates and serpentine.

The rocks found across the bodies or on the periphery, are late-stage intrusions that are characterised by large amounts of disseminated calcite, olivine macrocrysts and less than 15% by volume crustal xenoliths.

In the eastern, northern and southern sides, the project area is surrounded by Proterozoic rocks of the Labrador Fold Belt, the Cape Smith Fold Belt and the Grenville Province respectively. The entire area is hosted by minor linear belts of east-west or west-north-west trending supracrustal metavolcanic rocks. 

Mining

A combination of open cast and underground methods will be used to mine the area.

 Open pit mining at Renard 2, 3 and 4 pipes will be carried out at a rate of 2000tpd for five and a half years. The pits for Renard 2 and 3 will continue till a depth of 100m. It will extend 117m below surface for Renard 4. The open pit operations will provide 9.4% of the total mill feed.

Underground mining will be implemented in Renard 2, 3, 4 and 9 pipes. These pipes will contribute approximately 57.5%, 3%, 25.5% and 14% of the underground material.

In the initial three years underground mining will be carried out together with open pit mining at 1500tpd. In the fourth year, underground mining will be undertaken at a rate of 3000tpd. By the seventh year, the rate of underground mining will reach 5000tpd.

A 4.5m by 5.2m decline will be driven from the surface to access the underground operations. Access to a depth of 810m will be through a 6m diameter shaft that will allow mining of the Renard 2, 4 and 9 pipes.

During underground mining, two types of stoping methods will be used. The blasthole method will be used for Renard 3 and 9 pipes. About 163mm diameter holes will be drilled on a 5m-long and 5m-wide pattern. The stopes will be 40m to 100m high.

To provide initial ore, this technique will be selectively used on Renard 2 pipe between level 150m and 200m. Since the Renard 9 pipe is encroached under a body of water, it will not be mined to its surface. Instead it will require a 100m crown pillar.

Assisted block caving method will be used for the larger pipes Renard 2 and 4 that are suitable for caving. Drill drifts or levels will be installed at vertical intervals of 100m. Holes with 163mm diameter will be drilled on a 5m by 7m pattern.

Processing

The mine produce will be processed in five phases in a 1.3tpa (3,500tpd) diamond process plant. The capacity of the plant will be augmented to 5,000tpd after the initial three-year period.

Kimberlite will be mechanically processed with very little chemicals / reagents used.

Primary and secondary crushing will be carried out in a jaw crusher, followed by cone crushing to produce -75mm sized plant feed. Ore preparation through high pressure grinding rolls (HPGR) will free the locked diamonds.

De-agglomeration and sizing of the HPGR product will be done using a rotary scrubber and vibrating screens. Through scrubbing and screening, clean materials will be produced that are suitable for additional size reduction, dense media separation (DMS) and fines disposal.

Washed and sized feed will be separated on the basis of density into diamond-bearing concentrate and a reject stream. The diamond bearing concentrate is returned to the diamond recovery plant.

Approximately -4mm diamonds and +4mm luminescent diamonds will be recovered using grease technology and X-ray respectively. The processing system will allow recovery of at least 96% by weight of all freed diamonds that are more than 1mm. The fine and coarse rejects will be disposed of.