Day 3's adventure took our group to Petra Diamonds' Cullinan Mine; an adventure that for many of our class was their first time experiencing an underground mining environment! The Cullinan mine is known around the world for having produced the world's largest gem-quality rough diamond known to exist. This diamond, called the Cullinan Diamond was measured to be 3106.75 carats. That size is almost impossible to imagine when compared to the 0.5 - 2 carat diamonds commonly found on some engagement rings! The Cullinan Mine has had more than its fair share of large and rare diamonds too. The mine has produced more than a quarter of all diamonds over 400 carats mined in history and is also the world's only significant source of, the highly sought after and extremely rare, blue diamonds! That's quite the resume for one mine to have and we're extremely grateful to have had the opportunity to visit such an amazing operation. To be more specific about the operation, the Cullinan Mine is both a block caving and sublevel caving operation that produces up to 12000 tonnes per day at a grade of approximately 35 - 40 carats per hundred tonnes. The deposit was discovered in 1902 and currently has reserves to allow the continued operation until 2038 and the mine has plans to push the life of mine even further with more exploration!
So moving on from the spectacular facts surrounding the operation, our day stated with a very impressive safety orientation to ensure our groups safety throughout our tour. Following the orientation, our group was acquainted with our PPE that would accompany each and every one of us throughout the remainder of the tour. Our group then travelled over to the northern shaft station to make our descent into the depths of the mine.
Our first destination took us to the 831 level (located 831 m below the surface). This level is the lowest production level in the mine. Pictured below is our current undergraduate executive president, Gordie Hannigan, as we begin the exploration of the underground mine in the 831 level shaft station.
The first of the main attractions to see when visiting a block cave mine for the first time is one of the many draw points. A drawpoint is used as the access point into the ore body to extract the ore with LHD's. Pictured below is one such draw point as we inspect its design.
Moving beyond the series of ore passes we encountered one of 6 rock breaker installations located on the south of the ore body. This particular one was having maintenance performed at the time of visit.
We then continued down ramp to the lowest part of the mine, the crusher level. This level is home to 6 draw crushers capable of crushing up to 2000 tpd each from a rock size of 500 mm to approximately 150 mm. The crusher room was by far the hottest location we encountered. Many of us related the air to sauna like conditions with many of our faces dripping with sweat after only a couple minutes in the area. Below is a photo of us climbing up the crusher's infrastructure, being careful to maintain our 3 points of contact.
The crusher house concluded our tour of the underground mine so we headed back towards the shaft station to make our way up to surface. Once we returned to surface we made a detour to the observation area that overlooked the part of the property that used to be home to the historic open pit. As seen below, the caving operation has led to the formation of what can only be described as shockingly impressive!
Dimensions of the rectangular abyss shown above are 1000 m, between the near and far edges, by 500 m, between the left and right edges.
After spending several minutes starring in awe of the view before us, we headed back to the mine buildings to return our PPE and receive a presentation on the history and future of the Cullinan Mine's operations. The information at the beginning of this post was obtained from parts of this presentation. Following the presentation, as what seems to be becoming a pattern, we were treated to a fantastic South African curry beef and rice lunch dish. Below many of us are pictured wolfing down our lunch after a long morning walking around the depths of the mine.
Before making our way back to the lodge, we finished off our day with a customary photograph with the mine's headframe pictured in the background. A special thank you to Pieter Boshoff and his team for organizing and hosting us throughout the day for this amazing experience! This tour has been yet another example of the amazing South African hospitality we have experienced over this trip!