Introduction to Monday January 23, 2017 article: John Gravelle, a mining industry executive, independent director and former Global Mining Leader at PwC, is Century’s guest author this week and shares his insights on new underground mining technology. Pollution-Free Breakthrough for Underground Miners More hard rock mining companies are seriously considering the use of battery powered LHDs (which are underground Load Haul Dump units a type of rubber tired front- end- loader) and underground Haul Trucks. The use of battery powered underground mobile equipment will move towards the tipping point in the next couple of years. I will refer to three reasons for the momentum to shift to battery powered equipment underground: 1. The technology is better - in particular, the use of lithium chemistries for more powerful applications has substantially improved. 2. More original equipment manufacturers ("OEM’s") have plans to offer more battery powered underground equipment - over a half dozen OEM’s had or were discussing such equipment at MINExpo 2016. 3. Battery powered underground mobile equipment complements autonomous mining and digital technology.

The evolution of Lithium-ion technology underground Kirkland Lake Gold ("KLG") started the evolution towards battery powered underground mobile equipment five years ago. KLG needed a ventilation solution to successfully mine a new high grade zone. If battery powered underground mobile equipment didn't work, the other solution was additional ventilation airways the cost of which, at that time, would have been too expensive. Since KLG didn't have a compelling diesel powered option for the expanded mining area, it was very motivated to make the battery powered solution work and succeeded in doing so. Artisan Vehicle Systems Inc. provided the electric power train that was incorporated into RDH Mining Equipment (a specialist mining equipment manufacturer in Canada) units at KLG. KLG later requested Atlas Copco (a worldwide manufacturer of mining equipment) to use Artisan Vehicle Systems power trains in its equipment. The building momentum In addition to KLG, Glencore, one of the world’s largest mining companies, is also considering battery powered equipment for its Onaping Depth underground nickel project in the Sudbury area of Canada. This project could not move forward with diesel equipment but the economics are substantially improved when using battery powered mobile equipment due to ventilation capital and operating cost savings. If nickel prices improve and this project goes forward it would be a powerful case study for the benefits of battery powered equipment. Also, Goldcorp Inc. plans to build its Borden underground mine in Ontario, Canada with all or substantially all of its underground mobile equipment being battery powered. Of particular interest, is that Borden will be the first time battery powered equipment will be used for a new mine which does not have ventilation challenges, necessitating use of battery powered mobile equipment. Sandvik Mining and MaClean Engineering have teamed-up to provide the battery powered mobile mining equipment at Borden. Borden is another pointer that the tipping point is near. Cost reduction and performance The benefits of electric power underground are well known providing: 1. Reduced health and safety concerns since diesel is considered by the World Health Organization to be a carcinogen; 2. Lower ventilation capital and operating costs; 3. Higher employee productivity given a work environment with substantially lower heat/humidity and noise; 4. More powerful equipment. For years the above benefits could be achieved through the use of electric underground equipment receiving power directly rather than through batteries. LHD’s receiving power via trailing cables and haul trucks receiving power via overhead catenary lines have been in use for years. (Vale Canada Limited’s Coleman mine in Sudbury is an example of this) But the cost of overhead catenary lines and mobility issues from trailing cable have limited the use. While cost of battery powered underground mobile equipment has historically been higher than diesel, many OEMs are now pricing battery powered mobile equipment at an amount close to the cost of diesel equipment. In addition to the cost of battery powered mobile equipment, the cost of the battery packs is also expensive. But battery powered equipment was still justified in niche situations such as the KLG mine and Onaping Depth mine where substantial savings from ventilation could offset the additional costs of battery power. Of key importance is to develop a new mine project or expansion of an existing while also considering the use of battery powered mobile equipment, so the ventilation capital cost savings can be achieved to offset the higher cost of battery equipment. With respect to performance, certain battery chemistries such as Lithium titanate, allow for a fast charge time - say 15 min- while others such as Lithium Iron Phosphate have longer charge times (typically 90 - 120 minutes). For the chemistries that allow quick charge, the charge can be done without removing the battery pack from the equipment. But for longer charge times, the battery pack likely must be removed to ensure equipment is not out of service for the longer charge time. A key performance issue is how long the battery can last between charges since that will impact the number of spare battery packs required. Tie-in of battery powered technology to automated and digital mining Battery powered mobile equipment is a necessary component of enhanced automation and digitization. Examples of how battery technology has enabled other technological advancement is drones and robots both of which are powered by battery rather than diesel. The use of battery powered electric mobile equipment underground is quickly moving to the tipping point and will enable mining companies to achieve the required impact on margins from automated and digital mining.