Bedrock at the Ekati Project is dominated by Archean granitoids, intruded by metagreywackes of the YK Supergroup and transected by Proterozoic mafic dykes. No younger cover sediments are preserved. Bedrock is overlain by Quaternary glacial deposits which are generally less than 5 m thick.

The 45 to 75 Ma kimberlites, part of the Lac de Gras kimberlite field, intrude both the granitoids and metasediments. The kimberlites are mostly small pipe-like bodies (surface area predominantly <3 ha but can reach as much as 20 ha) that typically extend to projected depths of 400–600 m below the current land surface. Kimberlite distribution is controlled by fault zones, fault intersections and dyke swarms.

The kimberlites are made up almost exclusively of volcaniclastic olivine-rich volcaniclastic kimberlite (VK), with lesser mud-rich, resedimented volcaniclastic kimberlite (RVK) and primary volcaniclastic kimberlite (PVK). In rare cases (e.g. Pigeon), pipes are dominated by or include significant proportions of magmatic kimberlite (MK). Economic mineralization is mostly limited to olivine-rich resedimented volcaniclastic and primary volcaniclastic types.

Diamond grades are highly variable. Estimated average grades for kimberlites that have been bulk sampled range from less than 0.05 cpt to more than 4 cpt.

As of 2020, Panda, Koala, Koala North, Fox, and Misery open pits, as well as the Koala, Koala North and Panda underground mines have all are now closed. Five remain as part of the planned mining activities to 2035 (Pigeon, Lynx, Sable and Jay open pits, and Misery underground).

Mining production has been ongoing at Pigeon Pit, and Lynx Pit. Mining production started at Sable
Pit in 2018. Misery Underground (MUG) commencing mining in early 2019. The MUG Project is mined using the sub-level retreat mining method.

Optimization study of the Jay Project is ongoing.

The kimberlite pipes at Ekati are approximately circular in plan view and are generally located within granite, a competent host rock. The ore-waste boundary is abrupt and is readily distinguished by rock type. Ultimate vertical mining depths are 300 m at Misery, 190 m at Pigeon, 300 m at Sable, 140 m at Lynx, and 360 m at Jay.

The open pits are currently mined using conventional truck-shovel operations and are developed in benches that are typically 10 m high. The Jay pit, due to the presence of overburden and significant resedimented kimberlite, will have double bench (30 m) configuration in granite and metasediment, single bench (15 m) configuration in kimberlite, and single bench (10 m) configuration in the overburden. Sable is planned on triple benches (3 x 10 m).

The main truck loading and haulage equipment currently in use are diesel hydraulic shovel/excavators with a bucket capacity of 12 m3 and 90 t capacity off-road haul trucks. The Jay mine plan assumes 225 t capacity off-road haul trucks for ore and waste haulage. The main loading units selected for Jay were 17 m3 loaders and 34 m3 shovels.

The Koala mine was mined as a sub-level/incline cave (SLC), similar to a block cave, and developed with sub-levels spaced 20 m apart vertically and 5 m x 5 m draw points on a 14.5 m spacing (centre to centre). The highest elevation production sub-level is located at 2050L, approximately 160 m below the base of the former Koala open pit. Ore production from the draw points is a combination of the blasted kimberlite and caved kimberlite that lies above the blasted zone through to the pit. As production proceeds, the top of the cave zone below the pit is constantly being drawn down, and the level and profile of the surface expression of the cave zone is closely monitored. Below sub-level 1850L the mine transitions to an incline cave, with the lowest production level located at 1810L.

Kimberlite is transported from the mines via a 1.37 m wide conveyor system hung via chain from the back of the conveyor ramp. The system consists of four main underground conveyor sections plus a surface “stacker” conveyor, with a transfer arrangement between each conveyor. All production mucking is carried out using load haul dump (LHD) vehicles, tramming to the remuck bays or loading 45 t capacity diesel haulage trucks. Ore is dumped into an ore pass system, and fed to a 500 t/h primary mineral sizer before loading onto the 2.4 km long conveyor system from Koala to the process plant. On surface, the radial stacking conveyor discharges to an 8,000 t surface stockpile.

Feb. 22, 2022 - Arctic Canadian Diamond Company (“Arctic”) and IHC Mining have reached an important milestone in the development of an underwater remote mining (URM) system for the extraction of diamond-bearing kimberlite ore from deep open pits at the Ekati Diamond Mine in the Northwest Territories of Canada. The URM system consists of a floating platform, an underwater mining crawler and a land based dewatering plant. Arctic has now awarded IHC Mining with a contract to build and deliver a Launch and Recovery Platform for the URM system. This contract is the first major equipment scope being awarded by Arctic for the URM system, following years of development work.

Arctic and IHC Mining started their cooperation in 2018 to jointly develop an innovative and integrated mining solution. The starting point for the development of the underwater remote mining system was to economically extract kimberlite from marginal kimberlite pipes and from deep extents of completed open pits. An important focus was to develop a mining solution that would have a much lower environmental impact than conventional mining methods. As the URM crawler is only mining the kimberlite ore and minimal waste, it significantly reduces the mine’s footprint. The URM solution could allow the Ekati Diamond Mine to extend its lifetime by at least 10 years.

The various components of the URM system will be tested step by step with a production trial at the mined-out Lynx open pit prior to moving on to larger depleted open pits. The first step will be the flooding of the Lynx pit in summer of 2022. This will be followed by testing of the Launch and Recovery Platform in the summer of 2023 and then by comprehensive URM system testing in the summer of 2024 including a trial mining operation targeting the extraction of approximately 150,000 tonnes of Lynx kimberlite ore.

The URM solution is a technological breakthrough for kimberlite diamond mining. A new innovative solution which originated from deep sea mining and trenching systems has allowed Arctic and IHC Mining to take the next step in the future of diamond-bearing kimberlite mining.

The current plant flow sheet uses conventional diamond process technology and consists of the following main process areas:

Primary crushing: where the ore is fed to a dump pocket by truck or front end loader and crushed using a primary MMD 1300 mineral sizer—the run of mine ore is reduced to approximately -300 mm at this stage; an MMD 1000 is available to improve primary crushing overall equipment efficiency (OEE) when the primary crusher is off line for routine maintenance;

Secondary crushing: where a wet cone crusher reduces the primary crusher product to -75 mm;

Tertiary crushing: where HPGRs liberate locked diamonds from the kimberlite ore, in the size range of -75 +1.0 mm, and from recirculated -28 +10 mm material from the DMS float circuits;

Primary and secondary scrubbing, followed by screening: where crushed ore is wet-scrubbed and screened to produce clean and suitably-sized material for further size reduction (-75 +1.0 mm), and concentrated by DMS treatment (-28 +1.0 mm);

Primary and secondary de-gritting: where unwanted fines (-1.0 mm) are separated from ore.

The Ekati processing plant was designed with a nameplate capacity of 3,000,000 dmt/a (9,000 dmt/d). Further efficiency improvements are planned to achieve 12,000 dmt/d in conjunction with the Jay project.

The recovery of diamonds from the processing of the host kimberlite ore at the Ekati Diamond Mine includes:
* Primary crushing—redundancy with primary, secondary, and reclaim sizers;
* Stockpiling—used as a buffer between plant and crushing;
* Secondary crushing (wet cone crusher);
* Tertiary crushing and re-crushing for further diamond liberation;
* Sizing, de-gritting, and desanding;
* Dense media separation;
* Final recovery:
- Wet high-intensity magnetic separation;
- Wet X-ray sorting;
- Drying;
- Dry single particle X-ray sorting;
- Grease tables;
- Diamond concentrate weighing and packaging, sorting, and preparation for transport to the Yellowknife sorting and valuation facility.