Saying that in-pit haulage is one of the major cost drivers in quarrying and open-pit mining is not making an overstatement. In fact, transportation, on average, accounts for about 30% of total mining costs at most opencast mining operations, which is why operations such as Blurock Quarries are at the forefront of investigating ways to reduce costs directly linked to this function of their operations.
In an environment where market conditions have been depressed for the past three years, Jeremy-Hunter-Smith, CEO of Blurock Quarries, and his entire team, have been hard at work identifying areas of improvement, with haulage being one of the principal areas of consideration. Why haulage? Hunter-Smith tells Quarrying Africa that improving haulage efficiency directly impacts profitability and productivity. Optimising haulage reduces costs, increases production and minimises environmental impact, making it a key factor for quarry success.
As part of optimising haulage efficiency, the quarry has implemented a number of initiatives, including shortening hauling distances, designing haul roads for downhill hauling of loaded articulated dump trucks, and focusing on creating stable, well-maintained haul routes.
In addition to these initiatives, Blurock Quarries has also started investigating the possible change in hauling gear to squeeze more efficiencies. This drive was behind the recent decision to trial the Scania G460 XT mining tipper.
“Having come out of a very difficult business cycle, the timing to put the Scania mining tipper to test was just perfect for us. In the past three years, we have endured a difficult period, especially with an onsite asphalt plant being mothballed due to lack of meaningful road projects in the area. We therefore started looking at potential cost-cutting initiatives and efficiency improvement projects and one of the areas we considered was in-pit haulage, which is why we jumped at the opportunity to try the mining tipper and see how it compares with the traditional articulated dump trucks (ADTs) we have always run,” explains Hunter-Smith.
How did it fare?
The overall impression from the operations team on site, from the driver to the quarry manager, is that the Scania mining tipper performed beyond expectations. Given that the drive was all about efficiencies, the first area of consideration was fuel consumption. Deployed to haul run-of-quarry material from the muckpile to the primary jaw crusher, the mining tipper consumed about 8,2 litres of diesel per hour.
While this was pretty much on par with the 30-tonne ADTs that the quarry has been running, the Scania tipper achieved 40% more payload, confirms Hunter-Smith. The 30-tonne ADTs offer a 25-t payload capacity, while the Scania mining tipper, with its 60-t gross vehicle mass (GVM), has a rated payload capacity of 40 t. However, the Blurock team generally loaded between 35 and 37 t payload, which is 10-12 t more than that of the 30-t ADT, yet the trucks still had the same fuel consumption figures.
In fact, says Vinesh Kalu – key account manager – Scania Mining at Scania South Africa, there was room to squeeze more efficiencies, given that 57% of the fuel consumed was through idling. According to Scania’s fleet management system, of the 8,2 litres of diesel the truck consumed per hour, only 5,9 litres was dedicated purely to driving.
The excessive waiting times at the loading and tipping points were purely because the site was not geared for an extra truck in its hauling system as this was just a trial session. In an environment where these bottlenecks are non-existent, there is room to haul more for even less.
For Hunter-Smith, it would be ideal to pit the Scania mining tipper against a 40-t ADT. While the two trucks would ideally move the same payload, about 35-36 t on average, the Scania mining tipper would be much more fuel efficient. The massive difference in the capital cost would also be another big cost factor to consider. To provide context, in terms of purchase price, the Scania mining tipper costs about 42% less than a premium 30-t ADT, and this is bound to be even more when compared with a 40 t articulated hauler.
However, Kalu is quick to point out that for operations to achieve maximum value with a Scania mining tipper, it is important to ensure well-maintained, debris-free haul roads. While this offers numerous benefits, including increased productivity and efficiency, reduced costs and enhanced safety, it is particularly key to reducing tyre loss.
Productivity matters
Commenting on the truck’s productivity, Avinash Mahabeer, TMM team leader at Blurock, says the truck’s massive 40-t payload enables consolidation of loads and thus reduces the amount of vehicle movement required to distribute a given quantity of material on site.
“For example, we generally run with two 30-t ADTs in our hauling cycle. One day we decided to stop the two ADTs and deployed the Scania mining tipper alone. The large payload capacity and faster cycle times meant it could easily feed the plant with no issues, effectively replacing the two ADTs in the hauling system,” says Hadebe. The truck’s high payload yields economic, safety and environmental benefits. In addition, fewer trucks on site translate into less operating costs related to maintenance.
To sustain the increased payload, explains Kalu, the new XT mining tipper benefits from a robust suspension. It is equipped with heavy-duty rear axles with cast-iron housings to stand the test of challenging, rough mining conditions. Both rear axles are equipped with shock absorbers to improve traction and comfort.
Beyond expectations
Apart from the fuel efficiency, David Hadebe, production manager at Blurock, was impressed by how effortless and comfortable it is to operate the vehicle. One of the contributing factors to this is the Scania Opticruise gearbox, which ensures smooth, automated gear changing, thus reducing driver fatigue. Scania Opticruise, one of the first automated gear changing systems on the market, has over the years been refined, and is said to be one of the smoothest and smartest systems on the market.
When the truck first pulled up on site, quarry manager Morne Conradie was sceptical of its ability to take on the rugged conditions of in-pit haulage. One of his hesitations was the truck’s ability to haul downhill with a full load. “At first, I was concerned about the braking capacity of the truck going downhill with a full load. After driving it for the first time, I was pleasantly surprised by the retarding capacity of the truck,” says Conradie.
The five-stage Scania Retarder (hydraulic auxiliary brake that acts directly on the drive shafts) improves braking performance and reduces wear on the wheel brakes, especially on downward slopes. The retarder works independently of the standard wheel brakes and provides additional braking power, particularly useful in downhill situations.
While the haul roads at Blurock are designed for downhill hauling of loaded trucks, Conradie was also impressed at how the Scania mining tipper made light work of hauling uphill at gradients of up 11 degrees (24%) with a full 35-t load during testing. In addition, Conradie was immediately happy with the fact that the truck’s speed could be governed to meet Blurock’s 25-km speed limit requirements.
Mindset shift
While there is a general belief that yellow metal haulers are principal hauling solutions for in-pit haulage, Hunter-Smith believes it is time for quarries to start opening up to new ideas. While quarrying has always been referred to as ‘other’ within the mining sector, he says, it is governed by the same legislation as the mainstream mining sector.
Given that the industry mines a low-value, high-volume product, the constant change in legislation, which by its nature is very expensive to comply with, has meant that aggregate operations have found it extremely onerous to stay on top of costs and need to look at new ways to improve efficiencies.
“In fact, everything comes down to efficiencies,” stresses Hunter-Smith. “Given our challenges as an industry, exacerbated by the generally low business activity in the past few years, we must think outside the box and start looking at new ways to increase efficiencies. Let us not be afraid to try new things, such as the Scania mining tipper. I encourage other quarry owners to test this truck and see if it works for their operations.”
Jeremy Hunter-Smith, CEO of Blurock Quarries, on the decision to test the Scania mining tipper and how the truck fared during a month-long trial.
