In south east Missouri, Volvo articulated haulers are working in the mines of the Viburnum Trend, an area well known for its rich offering of valuable mineral deposits, including zinc, copper and lead in the Midwestern state of the US.
At 64km (40 miles) long by an average of 152m (500ft) wide – and in some parts as thick as 30.5m (150ft) deep – the Viburnum Trend, commonly called the Lead Belt in south east Missouri, is one of the most significant bodies of ore in the world. Before mining operations began, the trend was estimated to contain mineral resources of a staggering 500 million tons.
The Lead Belt contains the highest concentration of galena in the world, the natural mineral form of lead sulphide. It’s classed as the most important lead ore mineral in order to make different types of metal for construction works.
Located in Midwestern America, Missouri is surrounded by eight other US states. The first mine in the state opened in 1962 and over the past 50 years, five different companies have operated 11 different mines within the Viburnum Trend. Today, this number has dropped to six, and all of the mines are now owned by a single company: The Doe Run Company.
To help the company mine its six lead quarries, Volvo Construction Equipment (Volvo CE) articulated haulers are working under and over ground to increase operational safety, productivity and efficiency across all sites.
To recover the metals buried 1,000ft underground, Doe Run’s Southeast Missouri Mining and Milling Division (SEMO) must first haul the blasted ore to a shaft where it can be lifted to the surface for processing. From Casteel Mine in the north to Fletcher Mine in the south it is possible to drive 22 miles – although the maximum haul distance is around five miles.
The SEMO Division has been using Volvo CE for underground transportation for almost 20 years. “We started running Volvo A30 haulers to transport ore underground in the mid-1990s,” says SEMO general mine manager, Greg Sutton. “Fairly quickly, within a year or two, we moved into Volvo A35 trucks at some of the other mines. In about 1999, we got our first A40 truck.” Today, 23 out of the 45 trucks in the four large mines come from Volvo CE.
The haulers are required to transport approximately 5.5 million tons of ore every year, so it’s vital that the trucks are both robust and reliable. “Volvo Construction Equipment is a great partner for us,” says Greg. “The machines are consistently dependable, easy to maintain and have brought so many benefits in line with our main principles of safety and dedication to the environment.”
Of the 23 Volvo articulated haulers in the Viburnum Trend, 19 are A40D units. The other four are A40E FS full suspension haulers. Full suspension, an exclusive Volvo CE feature, uses electronics and nitrogen gas to help cushion the ride and level to load. “Full suspension absolutely enhances our hauling production,” says Greg. “It’s easier on the truck and the operator.”
Because of their full suspension status, the A40E FS haulers are allowed to run two miles an hour faster than the other machines. “Our underground speed limit for the non-full suspension trucks is 27 miles an hour,” says Greg. “But with the full-suspension units we can bump that up to 29.”Given the winding nature of the tunnels, average speed rarely tops 15 miles per hour but the full-suspension units still allow for a much smoother ride. “Because of this, I would estimate that we get 5-10% more production from the full-suspension trucks.”
The Volvo articulated haulers and their operators also play a significant role in maintaining the SEMO Division’s exemplary safety record. The mines of the Viburnum Trend have a reputation for being some of the safest in the world and each year, the U.S. Mine Safety and Health Administration present the Sentinels of Safety Award to the operation that works the most man-hours in a year, without a single accident in its respective classification.
Two years ago, the Sweetwater mine won outstanding safety performance in the Large Underground Metal Mine category for the eighth time. Since 1971, the mines have won the Sentinels of Safety award a whopping 25 times.
“At Doe Run we have a huge commitment to safety and Volvo CE is a considerable part of that, as it also prides itself on safety in the work place,” concludes Greg. “We always want people to go home every day in the same shape they arrived in. Without the quality equipment and service we get from Volvo CE, that’s a goal we might not be able to achieve.”
Picture 1: Making tracks through rough and rocky surfaces
Picture 2: The Volvo A40 D towers above the job site
Picture 3: The Volvos travel underground through the mining tunnels