Kimberlites and lamproites are volcanic and subvolcanic varieties of ultramafic rocks and are the main hosts for terrestrial diamonds. The vast majority of global primary diamond mines are hosted in kimberlite, and this rock type is the target at the Chidliak project. Kimberlites are mantle-derived, volatile-rich ultramafic magmas that transport diamonds from depths of 150 to 200 km to the earth’s surface, together with fragments of mantle rocks from which the diamonds are directly derived (primarily peridotite and eclogite). Kimberlites occur at surface as volcanic pipes, irregular shaped intrusions, or sheet-like intrusions (dykes or sills). Due to the wide range of settings for kimberlite emplacement, as well as varying properties of the kimberlite magma itself (most notably volatile content), kimberlite volcanoes can take a wide range of forms and be infilled by a variety of deposit types, even within a single kimberlite field, like Chidliak.

The Chidliak kimberlites are stratified bodies and different pipes contain different types of infill ranging from VK (Volcaniclastic Kimberlite) only to mixed VK, ACK (Apparent Coherent Kimberlite) and CK (Coherent Kimberlite) deposits (referred to as combined infill pipes). None of the Chidliak pipes contain massive VK-type infills like observed in many southern African kimberlites and in Canadian pipes at Gahcho Kué or Renard (Field and Scott Smith, 1999; Field et al., 2008, Fitzgerald et al., 2009; Hetman et al., 2004) ........

It is planned to open pit (OP) mine the Chidliak CH-6 and CH-7 deposits. Mining of the deposits will produce a total of 9.5 Mt of processing plant feed and 75.1 Mt of waste (7.9:1 overall strip ratio) over a 13-year mine life.

The current life of mine (LOM) plan focuses on achieving consistent plant feed production rates, and early mining of higher value material, as well as balancing grade and strip ratios.

The pit shells for Chidliak were further analyzed and optimizations were conducted in order to better define the possible stage shapes within the ultimate pit limits. It was decided to divide the pit sequence into three stages at CH-6 and two stages at CH-7 for the mine plan development to maximize the grade in the early years, reduce the pre stripping requirements, and to maintain the process facility at full production capacity.

The current LOM plan focuses on achieving consistent processing feed production rates, mining of higher value material early in the schedule, balancing grade and strip ratios, while trying to maximize NPV. Mining would commence at CH-6 and then moves onto CH-7 later in the mine life.

Year -1 represents the planned commencement of pre-stripping at CH-6. The average mining rate over the LOM will be 16,500 t/d, reaching a maximum of 28,200 t/d from Year 1 to Year 6. During full production, the mine, on average, is estimated to produce 1.3 Mct/a with a LOM average mining head grade of 1.8 ct/t.

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