Diavik Diamond Mine Evaluation
Info: 7719 words (31 pages) Dissertation
Published: 9th Dec 2019
Tagged: Earth SciencesGeology
Diavik Diamond Mine
List of figures
Figure 1 – Property location map
Figure 2 – Aerial view of the mine site
Figure 3 – Distant aerial view of the mine site on summer
Figure 4 – Regional geology of the site
Figure 5 – The kimberlite pipes on the site
Figure 6 – The annual winter road connecting Diavik to Yellowknife
Figure 7 – Site facilities and infrastructure
Figure 8 – Underground developments for the three main pipes
Figure 9 – Ventilation system for the underground complex in Diavik
Figure 10 – Benches the A154 open pit at Diavik
Figure 11 – Blast-Hole Stoping with backfill
Figure 14 – Barren-land caribou on the Northwest Territories
Figure 15 – Human activities in the Northwest Territories
Figure 16 – One of the 2.3MW turbines on the site
Figure 17 – The Foxfire Diamond
Table 1 – Remaining mineral resource estimation as at December 31, 2016
Table 2 – Mineral reserves estimation as for December 31, 2016
Contents
2.1. Description, location and climate
2.2. Accessibility and local resources
3. Deposit types and mineralization
3.2. Mineral resources and reserves
4. Site infrastructure and mining methods
4.3. Mineral processing and recovery
5. Environmental and social aspects
5.1. Environmental Impact and closure plans
5.2. Social or Community Impact
Appendix A – Cashflow analysis
Mining is known to be one of the primary industries of Canada representing about 4% of its Gross Domestic Product (GDP) in 2016. Thanks to its rich geology, Canada is considered one of the largest mining nations in the world. It produces more than 60 different minerals and metals and is among the main producers of some of them, including potash, uranium, niobium, cobalt, indium and least but not important, diamonds.
In the Northwest Territories (NT), 300 km Northeast of the city of Yellowknife the Diavik Diamond Mine is located. This one which is the biggest diamond mine in Canada produces about 6 million carats a year. The mine represents one of the main sources of income and employment on the Northwest Territories. Diavik, along with the neighbour Ekati Diamond Mine, account for over 20% of the Northwest Territories’ GDP.
Despite its contribution to Canadian settlement and development, in recent years the mining industry has been criticized for its environmental and social impacts. As a result, the mining companies have been constantly trying to improve their performance and prosper while achieving a more sustainable operation. Diavik is a world class diamond mine in one of the most challenging environments in the world, the subarctic tundra. Despite that, the mine is an example of environmental commitment and social support. The former can be evidenced by the 9.2 M capacity wind farm that the mine employs.
The aforementioned facts lead the mine to be chosen for this project. Which intends to present a study on the mine’s site, infrastructure, operation and mining characteristics.
Diavik Diamond Mine is an operating mine located at Lac de Gras in the Northwest Territories, approximately 300 km Northeast of the city of Yellowknife in the arctic barren lands. The exact location is indicated on the map on Figure 1. It produces about 6 million carats of diamond per year. The mine now works fully underground but started as an open pit mine in 2003. Open pit operations are expected to restart at the present year (2008).
Figure 1 – Property location map
Source: Blowes et al. (2007)
The Diavik Diamond Mine is owned by the Dominion Diamond Diavik Limited Partnership (“DDLP”) and Diavik Diamond Mines Inc. (“DDMI”), 40% by the former and 60% by the latter. DDDLP is a wholly owned subsidiary of the Dominion Diamond Corporation, headquartered in Yellowknife and DDMI is a Canadian subsidiary of RioTinto plc of London.
The mine is built on four diamond-bearing kimberlite pipes, all within five kilometres of each other. From those pipes, three are currently in production and the fourth one is in development. The beginning of the explorations of the fourth pipe will bring back the open pit activities for a few years. All of the four kimberlite pipes are located in the water under the lake (Lac de Gras). For mining the orebodies to be possible dikes needed to be built to hold back the water of the lake. The dikes surround the whole excavation area and will keep the operations dry until the end of the mine life when the lake will be re-established. Those can be seen on the aerial picture of the mine in Figure 2.
Figure 2 – Aerial view of the mine site
Source: RioTinto (2017)
The site is on a very remote location within the sub-arctic circle therefore harsh winter conditions are predominant for the longest part of the year. There are only five months where daytime temperatures are above freezing point. The mean annual temperature at the property is -12°C but on summer the temperature can raise up to 25°C. The average minimum temperature is about -35°C but it can reach below -50°C. This means that the mine needs to heat intake air during most of the year. Because of its high latitudinal position daylight can last up to 22 hours on summer (in June) and only four hours on winter (December). High speed winds are common on the site averaging 20km/h on typical days. Which made it a good option for Eolic energy utilization. The mine operates 24 hours a day, seven days a week all year-round except during whiteouts (huge blizzards that reduce visibility to near zero) which happen typically four times each winter lasting 8 to 12 hours.
The Diavik Diamond mine is a remote site located 300km northeast of its nearest major center, the city of Yellowknife which is the capital city of the Northwest Territories. Yellowknife has approximately half of the population of the territory (about 40,000 habitants). The second closest major city is the city of Edmonton in the province of Alberta which is accessible through an 18-hour drive or by daily flights offered by four commercial airlines. However, Yellowknife has all the basic amenities found in an urban centre and it works as the main point of transportation and commerce for the mine.
It is an isolated site with strictly controlled access and security. Access by air is possible all year long but by land is only possible through a 350km ice road which is only available during eight to ten weeks per year, between January and March. The majority of the mine supplies, including explosives, fuels, construction materials, lubricants and machines are transported by this road which shows how well planned the operations have to be. Even other mining operations, explorations and camps depend on this ice road to Yellowknife. For the air ingress there is a 1.6km long airstrip which can accommodate passenger aircrafts (even a Boeing 737 as well as cargo ones. Flights from Diavik to Yellowknife and vice versa take about 50 minutes and are the main way of entry for most employees who work in a two-week rotation at the mine (followed by two weeks at home).
About 900 people work at the mine. Approximately 48% are residents of the Northwest Territories. Among those are a good number of workers from first nations. It is estimated that 19% of the workforce is aboriginal.
As a consequence of the remoteness of the site it is necessary that it operates as a self-contained community which means generating its own electricity (via diesel generator sets) and its own potable water. It also needs to manage its own waste including sewage and effluents. The site needs to have emergency response and medical services ready. There are also educational, dining and recreational amenities providing wholesome meals and single-occupancy quarters. All of the mine facilities as for working, tailings, mine rock stockpiles, ore processing and service facilities (like dining and accommodations) are integrated in a single site which is visible in Figure 3.
Figure 3 – Distant aerial view of the mine site on summer
Source: Rio Tinto (2017)
Originally Aber Resources Ltd. Began staking mineral claims in the Lac de Gras area in November 1991. Through an option agreement at 1992 Kennecott Canada Inc. acquired the right to earn a 60% joint venture interest on the Diavik claim blocks. The Diavik Joint Venture was consummated in March 1995. Kennecott assigned its rights and interests to Diavik Diamond Mines Inc. (DDMI), both are subsidiaries of UK-based Rio Tinto plc. Aber Resources would later become Aber diamond Corporation and assign its rights to a separate entity called Aber Diamond Mines Ltd. on 1998 which would then change its name to Harry Winston diamond Corporation in 2006 and finally become Dominion Diamond Corporation in March 2013. And the Diavik activities of harry Winston Diamond Mines were transferred to Dominion Diavik Diamond Limited Partnership (DDDLP). Leading to the final ownership of 60% by DDMI and 40% by DDDLP.
To identify the properties of the geological bodies, airborne geophysical helicopter based surveys with electromagnetic sensors and heavy mineral sampling were used. The bodies were then ranked in order of priority and more detailed exploration followed. Four potentially profitable kimberlite pipes were discovered under the waters of the Lac de Gras adjacent to East island. The first viable pipe was A21, found in April 1994, afterwards A154N and A154S were revealed in May 1994 and finally A418 in May 1995. The drilling was mainly made on top of the semi-frozen waters of the lake. The pre-feasibility study (PFS) was made between 1996 and 1997.
Construction of the site lasted from 2001 to early 2003 when the first dike was constructed around was to come the A154 open pit. The pool formed was dewatered and sediments were removed to expose the A154S and A154N kimberlite pipes and commercial production begun later that same year. All the construction materials, fuels and supplies were transported through the ice road from Yellowknife.
From 2005 to 2006 the second dike was constructed around A418 adjacent to the A154 open pit. Mining on the A418 started only in December 2008 when the open pit part of the A154N pipe was depleted. In 2009 production was shorted due to a drop in diamond prices and demand associated with a global financial crisis.
Underground production commenced in 2010 starting a three-year transition period to finish surface operation and become a fully underground mine. By the end of 2010 the open pit portion of A154S was depleted and in September 2012 open pit mining ended. The underground operations mine from the three pipes concurrently. The fourth kimberlite pipe A21 is currently under development and mining on it is expected to start by the end of this year following timing of capital investment and maximum benefit for production.
The mine is located on East Island in Lac de Gras on the central part of the Slave Structural Province forming a cratonic block in the Canadian Precambrian Shield. A schematic of the geological setting is shown on Figure 4. It is possible to see that most of the rock formations surrounding the site is made of granitoids which gives the host rock on the orebody its high competence.
Figure 4 – Regional geology of the site
Source: Kip and Thompson (2017)
The area is known as the Lac de Gras Kimberlite field. A group of late Cretaceous to Eocene diatremes (volcanic pipes formed by gaseous explosions). This field supports both Diavik and its neighbour mine Ekati Diamond Mine. The Kimberlite pipes are Eocene volcanic deposits that intruded older Archean granitoid and metasedimentary rocks. They and their host rocks were covered by a Quaternary glacial till (unsorted erosion sediment) generally up to 40 m thick near the pipes.
The resources and reserves for Diavik consist on the four diamond-bearing kimberlite pipes located (previously) under the water of Lac de Gras (“Fat/Rich lake”). The pipes, which are represented in Figure 5, are considered small but high in grade. The fourth pipe A21, as mentioned before is the only one not yet in production.
Figure 5 – The kimberlite pipes on the site
Source: Kip and Thompson (2017)
Usually the diamonds are incrusted as xenocrysts in the kimberlite magma as it goes up onto the earths surface. As it approaches the superficies the volatile substances on the magma such as CO2 expand forming the characteristic conical structure of the pipes. The kimberlite in the pipes is a mixture three facies: Volcaniclastic kimberlite (VK), Pyroclastic kimberlite (PK), Coherent kimberlite (CK) and country rock. CK is formed by crystallization of kimberlite magma, often at depth. PK at Diavik is seen as material that fell from volcanic explosion that could be deposited in water. VK is formed by pyroclastic deposition and re-sedimentation of PK and host material from volcanic eruption. There is also the host rock dilution incorporated on eruption process. At Lac the Gras the kimberlite is softer than the ground surrounding it which causes depressions to happen on the top of the pipes that consequently fill with water becoming lakes.
The total tonnage for both resources and reserves is calculated from volumes estimated and/or measured. To those volumes, average values of density calculated from samples using ordinary kriging. All the pipes are based on multiple passes of ordinary kriging with similar parameters as similar densities happen on each pipe. From that data, the remaining mineral resources are estimated as seen on Table 1 . Mt, cpt and Mct represent million of tonnes, carats per tonne and million of carats per tonne, respectively. These are the materials remaining after the reserves are extracted. They could become profitable reserves one day but it is important to remember that these amounts are only resources and not reserves because they didn’t demonstrate economic viability.
Table 1 – Remaining mineral resource estimation as at December 31, 2016
Source: Kip and Thompson (2017)
The dilution happening on the process depends on the mining method applied and was considerably low mainly for open pit mining which levels were around 2%. That is caused by the kimberlite being softer than the host rock making it easy for it to be peeled away from the waste rock leading to a straightforward separation of ore and waste. Which also lead to barely no mining losses on the open pit. For the underground methods the values varied between 5 to 12% dilution and losses were about 5% for all of them.
Conversion from resources to reserves are based on confidence in mineability and economics. In the Diavik estimations it is possible to use the interpretation that the measured resources were turned into proven reserves and indicated resources into probable reserves. The inferred resources were not included in reserves. The overall estimation of the still existing reserves is demonstrated on Table 2. The displayed values only refer to not yet mined material and consequentially what is left to me mined until the mines depletion expected to be around 2025.
Table 2 – Mineral reserves estimation as for December 31, 2016
Source: Kip and Thompson (2017)
As previously said the site is isolated in a location in the Canadian sub-arctic and must work as an independent facility, being responsible for its own energy, water and sewage for example. Most of its construction materials, fuel, supplies, explosives and equipment is transported in the annual 350km winter road constructed on ice. The road is a joint venture between the Diavik, Ekati and Gahcho Kué diamond mines, all of which operate in the region. These mines share the construction, operation, maintenance and closure costs of the annual roads. Other projects and explorations sites also use it on a toll basis. The road is shown on Figure 6.
Figure 6 – The annual winter road connecting Diavik to Yellowknife
Source: Kip and Thompson (2017)
The average freight per season is about 120,000 to 330,000 tonnes. Because of the short window of time for the road the mine’s planning of freight has to be precisely executed.
For year-round access everything is done by air. The airstrip present on site meets the federal air transport requirements and has runway lighting, air traffic control centre and areas for offloading, parking, fueling and boarding. Personnel are transported to and from the site using small commuter aircraft.
On the site, all kinds of facilities exist to make it possible for the workers to be accommodated comfortably. There are occupancy quarters, dinning, recreational and educational facilities. Other conveniences like a large administration and maintenance complex also exist on the site.
Figure 7 – Site facilities and infrastructure
Source: Kip and Thompson (2017)
All of the sites electricity is generated locally. Six 18-million-litre diesel fuel tanks, which can all be seen in red on Figure 7, hold the whole year’s supply of fuel for heating, mobile equipment and power generation. The site has two diesel generation plants plus a four-turbine wind farm. The first large-scale system in the Northwest Territories and an innovation in renewable energy for mine sites. The four Enercon 2.3 MW turbines installed in 2012 meet 10% of Diavik’s power needs.
Another interesting part of Diavik’s infrastructure are the two dikes constructed to hold back the waters of the Lac de Gras to allow the mining operations on the kimberlite pipes. These dikes are results of advanced construction techniques developed by DDIM specifically or this project and have several layers of concrete to guarantee that the 12 to 20m deep waters of the lake will be contained and the underground operations will carry on protected under the pits. One dike is 3.9km long and surrounds the A154 open pit and another one is 1.3km long and surrounds the A418 pit. A third one is being constructed on the A21 pipe where the open pit will be located. Construction is expected to finish later this year. The dikes are constantly monitored with sensors to make sure they are stable an under control.
Other facilities located on site include an ore processing plant, electrical distribution networks, a boiler house, maintenance shops, fuel storage tanks and processed kimberlite containment (tailings), water storage ant treatment facilities. There are several pumping facilities on the pits as well as underground to deal with the high volume of water that infiltrates the site due to the presence of the large mass of water surrounding the location. An schematic of the underground developments is shown on Figure 8.
Figure 8 – Underground developments for the three main pipes
Source: Kip and Thompson (2017)
Because of the extreme cold environment in which it is located the mine ventilation air that goes into Diavik underground workings has to be heated up to 5-7° prior to entry, which is achieved by diesel burners on the air intakes. The original primary ventilation scheme used in the mine had a push-pull system with a combined negative pressure balance to ventilate the mine. It had a total of approximately 472 m³/s of air intake. Due to expansions in the underground structure and changes in the mine over time the old arrangement had to be updated to a higher flow, positive pressure ventilation system. The implementation of the new system was completed in 2012. It takes about 740 m³/s (1,567,000 cfm) of intake air. A schematic of the final ventilation system is displayed on Figure 9. The main ventilation system has 3x450HP fans (with heaters), 2x150HP fans (with heaters) and 2x200HP fans (without heaters). A list of all the ventilation equipment is described in detail on the Appendix B.
Figure 9 – Ventilation system for the underground complex in Diavik
Source: Robinson et al. (2014)
Mining in Diavik started with open pit mining as it was a low-cost bulk mining method that could provide a fast return for the initial investments. Open pit mining is the cheapest mining method and is usually applied always that possible (shallow or partially shallow orebodies) in mining operations. Each of the pipes had its top part as close as 20 m from the surface which made the method feasible. The country rock at Diavik is mostly massive and intact granite with rock strengths of 1000 MPa or higher, which much higher than the values found in the kimberlite. Because of that there is not much concern regarding slope stability and the face bench angles are found to be almost perpendicular to de ground which can be seen on Figure 10.
Figure 10 – Benches the A154 open pit at Diavik
Source: RioTinto (2017)
Beneath the pits underground mining was found to be economically viable for all of the first three pipes: A154N, A154S and A418. All of which started with open pit and after the depletion of reserves reachable by surface mining are being mining by underground mining methods. The meeting point between open pit and underground mining was calculated to be optimized for each of the pipes. No crown pillar was left for the A154S and the A418 pipes as they were high grade and it was profitable to use specific methods to extract them. Despite being depleted, the open pits are still under constant surveillance as their cohesion is vital for the dikes’ endurance and overall site stability.
The underground mining methods used for the pipes is Sub-Level Retreat for the A418 and A154S and Blast-Hole Stoping with Backfill for the A154N.
Blast-Hole Stoping (BHS) is used for the A154N. It consists in a bottom-up bulk method relying on the competence of the rock overhead. The method is very similar to Sub-Level Stoping but with less levels and parallel drill rigs. In Sub-Level Stoping main levels are excavated through the orebody and large stopes are drilled and blasted from them. The blasted rock falls and is mucked out through drawpoints. On BHS the blasted rock falls on top of the previous filled level and is mucked to an orepass down to the drawpoints. With it, several weeks’ worth of production is blasted at once. There is a high up-front cost associated with the bottom-up scheme that requires mining down to a lower level in the beginning. The backfill used is cemented rock-fill which is cheaper then cemented paste fill. That is why a Bottom-up method is necessary, because the ore here is stronger than the backfill used. Filling is necessary because of the proximity of the kimberlite pipe to the open pit walls and the dikes which have to remain stable for the sake of the production. Initially Underhand cut and fill was going to be used but it was discarded due to its higher cost. On the BHS with backfill each stope is blasted with parallelly drilled holes with the level below working as a haulage level and the one above being accessed for drilling. When the stope is totally mined, it is filled and the process repeated on the levels immediately above using the top of the backfill as a haulage level. The method is demonstrated on Figure 11.
Figure 11 – Blast-Hole Stoping with backfill
Source: Kip and Thompson (2017)
For the other two pipes (A154S and A418) a method called Sub-Level Retreat (SLR), also known as Sub-Level Caving, which relies on the low competence of the ore and high competence of the surrounding country rock. In it sub-levels are driven into the ore and the back is blasted on each one allowing the kimberlite rock to cave and the ore to be removed. No backfill is used in this method. Stability is not compromised because of the strength of the country rock that doesn’t cave along with the ore. However, as the method advances downwards there is a natural increase in the potential for granitic host rock material to fall from the walls onto the blanket of blasted ore. Some of the country rock has started to drop increasing dilution and generating discussions on whether the mining method should be updated. A representation of the method is shown on Figure 12.
Source: Kip and Thompson (2017)
The stopes for both methods are about 25m high. Both mining methods take place simultaneously and there are multiple faces from more than on level in concurrent production. Cement for backfill is trucked on the winter road. Ore is mucked out trough three portals to take advantage of the surface haulage equipment.
The fourth kimberlite pipe, A21 will be mined entirely using open pit mining due to is smaller size and greater distance from the other pipes and its underground developments.
The processing plant at Diavik is in continuous operation since its commissioning in 2002. Its initial capacity was 1.5 million tonnes of kimberlite per annum (Mtpa). It was later expanded to achieve a capacity of more than 2 Mtpa which is the average of the production ever since 2005. From 2013 Diavik was a full underground mine supplying more than 2Mtpa for processing. The A154S pipe will be depleted a little after the A21 mining starts keeping production more or less constant up to 2023 when it is expected that the mine output will continually decrease until is depletion as the mine gets deeper and the pipes smaller.
The processing plants uses no chemicals to separate the diamonds from the kimberlite. All the process is gravity-based relying on the heavier weight of the diamonds to separate them. After going to the crusher, the kimberlite is washed, sized and goes into screening. Then, a slurry made with ferro-silicon and water is added to the material and put into a dense separation tank. Afterwards it goes into an X-ray fluorescence cleaning process where the rays make the diamonds glow and sensors detect it sending signals to air blasts that blow the diamonds into collection receptacles. The waste is re-crushed and stockpiled. Recovered stones are then sent through sorters and then for human analysis to be measured and categorized. All of this happens on areas under strict security surveillance. Finally, the stored diamonds go to a secured vault while waiting to be sent for a final cleaning and sorting in a facility in Yellowknife where they are “split” in by size and value into shared for the two entities on the Diavik Joint Venture. A simplified diagram of the process is presented on Figure 13.
Source: Kip and Thompson (2017)
Present in the waters of the Lac de Gras and its neighbour lakes are several species of fish including trout, whitefish, arctic grayling, cisco and slimy sculpin. Bird populations are smaller as they are present mostly in the summer except for owls, hawks, falcons and ravens that can be found all year-round. Caribou are constantly present on the location as they migrate through the area to access spring calving and winter forage grounds, some of then are portrayed on Figure 14. Grizzly bears, wolves, foxes, wolverines, arctic hare and other small mammals and some other small mammals are also found in the lands of the site. These are the main species affected by the presence of the mine in the lake. The main effects are the loss of land-based and water based habitat for some of the species, intrusion on migration routes, excessive amounts of dust in the air of the surrounding areas including dust deposition on lichen which is a very important food source for the caribou. Also change in meteorological conditions around the mine, decrease in water quality round of the site affecting plankton and fish health.
Figure 14 – Barren-land caribou on the Northwest Territories
Source: Berdan (2017)
Among the species or groups of species affected five are considered the main source of concern as they are identified as valued ecosystem components (VECs). These being: barren-ground caribou, barren-ground grizzly bear, wolverine, raptors and waterfowl and shorebirds. To deal with those impacts the Diavik Diamond Mine has a full-time environmental staff responsible for constant monitoring potential effects of the mine on wildlife and its habitat. The mine’s environmental management system is ISO 14001 certified. The monitoring helps to determine if the predictions on the mine environmental impact assessment were accurate and also supports the assessment of the effectiveness of the mitigation plans. Surveys and supervision are conducted to check on wildlife, mainly on the five key aforementioned species. Besides this, many other major areas are monitored and controlled including water flow management, acid generation potential on waste rock, sewage water, treatment of effluent water and removal of suspended solids, ammonia, phosphorus and suspended solids in effluent water and the mine closure planning, reclamation research and the site rehabilitation activities.
The mining closure plan is organized since the project conception. It has been constantly updated based on long-term research which is always underway in the field and as the knowledge base grows as well as engagement from community members. After the mine life comes to an end there are strategies to restructure the environment on the area including closing mining areas, dismantling buildings, sealing the processed kimberlite containment, restoring the land and finally breaching the dikes to return the lake water to its original shoreline. Diavik Diamond Mine’s closure and reclamation liabilities have a financial security provision required under its water licence. This security amount is now about C$150 million. It will likely increase in the order of C$5 million to cover liabilities for the development of the A21 open pit.
From the impacted species mentioned before the caribou is the key indicator of environmental impact for their cultural and economic value to the northern residents as well as its ecological importance.
The area around Lac de Gras is largely populated by communities as can be seen on Figure 15. The closest one being Wekweeti, 187km southwest of the lake. Before the approval of the mine plan, cultural heritage assessment and archeological surveys were done on the area and approved as part of the mine development plan. During that time Diavik committed to giving priority in hiring Northern residents, aboriginals born on NT and West Kitikmeot on Nunavut and their descendants. This results in 49% of the mine’s workforce being natural of the Northwest Territories and 19% being first-nations members. DDMI has had an effective community program for more than a decade and will continue after the mine closure.
Figure 15 – Human activities in the Northwest Territories
Source: Kip and Thompson (2017)
There were three main agreements made with local communities, mainly five aboriginal organizations, on the mine development. Participation Agreements describing the community activities. Socio-Economic Monitoring Agreement with the government and the aboriginal organizations framing commitment to local employment, community well-being and surveying of those requirements by a board of representatives. Lastly Environmental Agreement providing funds for independent environmental oversight. The five first nation organizations are: Tly Cho government; Yellowknives Dene First Nation; Lutsel K’e Dene First Nation; Kitikmeot Inuit Association and the North Slave Métis Alliance.
The Mine development capital costs to construct the mine site were estimated in C$1.13 billion up to 2002 a large amount mainly to its structure necessary for the remote location of the mine and the dikes. The capital and business costs and spending on construction and operation expenditures from January 2000 to June 2013 sum up to more than C$6 billion most of which (C$4.3 billion) was spent through northern companies and C$2.3 billion with Aboriginal businesses. These costs cover the dikes construction, underground exploratory declines, bulk sample mining, site investigation and dike design, underground test mining, construction and development of the pits and underground mine and the four-turbine wind power farm.
Operating costs which account for normal and recurring costs of production including: mining underground and open pit, ore processing, site support (camp, logistics, pwer generation and distribution, water treatment, technical services and material management), corporate functions, private royalties, marketing costs and mine closure are estimated to be about C$171.20/tonne of ore processed in 2017 (C$91.37/tonne of which are for mining and processing). Revenue is estimated (also for 2017) to be about C$ 547.56/tonne of ore processed, consisting of an average grade of 3.49 carats per tonne (cpt) and US$ 118.13/carat (US$/ct). This information as well as the whole cash flow analysis for the following years is seen on Appendix A.
After several years of study on renewable energy resources, planning and feasibility studies on 2012 the Diavik Diamond Mine installed four 2.3MW ENERCON wind turbines totalizing 9.2 megawatts that on average supply 10% of the power capacity needed by the mine, achieving a peak power penetration of 52%. Several challenges are present on the harshly cold environment that can have temperatures as low as -40°C. But with major issues being solved the wind farm became fully operant making it the world’s largest wind-diesel hybrid power facility and the global leader in cold climate renewable energy. On its first year the wind farm resulted in a saving of more than 3.8million liters of diesel reducing emission of greenhouse gases for the mine in about 6%. One of the turbines is displayed on Figure 16 .
Figure 16 – One of the 2.3MW turbines on the site
Source: RioTinto (2017)
In 2015 a 187.63 carats diamond was discovered in the Diavik Diamond Mine site. It is the largest diamond ever found in North America. The diamond is believed to be two-billion years old and has a unique glow after exposed to light that makes it seem like it was emitting orange light itself. This is most probably caused by traces of nitrogen contained within the diamond. The unique glow characteristic is what gave it its name. It has an extraordinary quality, size and color. The diamond was bought by a Amadena Investments for a undisclosed amount and has traveled the world ever since, attracting attention from dealers and experts around the globe. If it wasn’t for the diamond’s elliptical shape as seen on Figure 17 it would have been crushed along with the rest of the ore.
Figure 17 – The Foxfire Diamond
Source: RioTinto (2017)
On the mining industry it is possible to find a wide variety of operations, be it for surface or underground mining. New orebodies in many different shapes with contrasting geometries, getting deeper and deeper, or further into remote locations. With their discoveries new technologies are developed to make it possible to mine them. More advanced equipment is created and more intricated techniques are conceived. Because of that, all those mines that would never be deemed possible to exist, conquer their way into reality.
After all this extensive research work it becomes clear that the Diavik Diamond Mine is one of those examples. This research also shows why it is important to conduct works like these. There are only a few more enlightening practices than getting to know the whole history, process and operation of a mine, perhaps not even visiting the mine itself.
Diavik is a mine in one of the most remote and challenging environments for such an operation and it keeps overthrowing all the adversities in its way with developments in engineering and science. Not only that, Diavik is also succeeds in community and local support, mainly because of its plans and agreements for the benefit of the local communities. It is certain that even after the mine’s life ends, its inheritance will continue, if not in the form of knowledge, certainly in the form of its main commodity. Because the diamonds, like the Diavik Foxfire, those are forever.
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- Amadena Investiments. (2017). HISTORY. Retrieved April 02, 2018, from https://foxfirediamond.com/history-home#history.
- Robinson, G. Gherghel, C. De Souza, E. (2014). Positive Pressure Ventilation System Conversion at Diavik Diamond Mine. Airfinders Inc.
Appendix A – Cashflow analysis
Appendix B – Ventilation Equipment
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