Gord: Before deciding on equipment, it’s essential to know how much material the mine has to produce to make it profitable. From that point, you have to work backwards to determine how much material you must move to achieve that. Once you’ve done the pre-strip (removal of organics – which later aide in reclamation), there’s still overburden because of what we call the stripping ratio - the amount of waste rock you have to remove versus how much ore you have to move. That can vary. Let’s say 20,000 tons of ore must go to the plant daily. If you have a five-to-one stripping ratio, you have to move 100,000 tons of waste rock to get that 20,000 tons of ore. So, your equipment fleet would have to be sized to move 120,000 tons per day, matched to the distance the total material must move.
Gord: To move that 120,000 tons of rock, you must size your trucks, excavators, and loaders accordingly. However, you’ll never get a perfect match – you’ll either keep trucks or shovels waiting. But, generally, shovels are your most expensive resource, and they’re the ones we want to keep producing. As we say, you want to be shovel-dependent (trucks waiting to be loaded at shovel), not truck-dependent (shovel sitting waiting for another truck).
So, you do the calculations, which depend on the size of the bucket you’re using and the size of the truck. If it takes three and a half minutes to load a truck, and the truck takes ten minutes to carry the load, dump it, and return, plus the time to back in and pull out, you’ll probably want five trucks to keep that shovel or excavator busy.
Of course, with everything depending on the shovels, you need to be prepared if one goes out of service. It’s critical, therefore, to have proper maintenance support. Many of our customers also have wheel loaders as backup, so you can at least keep production going.
Gord: In addition to having the truck capacity to exceed the required amount of material and the required distance, you also need to figure out the optimum loading cycle. If it takes only three passes to fill the truck, there’s a considerable risk of overloading it. On the other hand, it’s inefficient for the shovel if there are more than six passes. Usually, the optimum number we aim for is four to six passes. So, size matching is important.
The other issue is that if you depend on a small number of large trucks and one goes down, you lose a significant portion of your capacity. Sometimes, running a slightly larger number of “smaller” trucks is better to reduce that risk. For example - If your size matching calls for only three trucks, it might be better to look at trucks where you would require four trucks.
Gord: In many mining situations, it’s not easy for operators to know whether they’re moving ore or waste. Of course, they’ll have their survey data, but that might not be easy to access from the excavator's cab. Leveraging data is where smart mining comes in. Komatsu machines equipped with smart mining features and Modular Mining software technology give operators access to a digital model of the mine. Using these technologies ends guesswork around what they’re digging, increasing the operation efficiency. It also avoids inadvertently sending waste to the plant.
Smart mining technology also allows a dispatcher to see the big picture of a large operation and direct the trucks to go where they’re needed the most so that shovels won’t be sitting idle. The best way to ensure the shovels are kept busy is to automatically assign the fleet using Modular Mining’s Dispatch, which is like Uber for mining trucks (and definitely rates five stars).
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