Limestone makes for cleaner coal

Limestone makes for cleaner coal

Helping clean coal mining and power generation is the job of Volvo CE-equipped New Mexico limestone producer, C&E Concrete.

The parched land of central New Mexico once yielded uranium, a heavy metal that fueled the U.S.’s nuclear power program. However, mining the material has lain dormant for decades and in its place, limestone; a more common, useful and less volatile mineral is the new mining mineral of choice.

C&E Concrete is a leading producer of milled limestone for use in coal mines and power plants. The company is extracting a pure form of limestone from its Tinaja pit, a stone’s throw from Albuquerque. Established in 1974 by Walter and Norma Meech, C&E Concrete quickly built a reputation in the southwestern region of the US as a mining specialist, following the discovery of pure calcium carbonate – something the Tinaja pit has plenty of.

The Tinaja pit houses limestone that is around 25.9 m (85 ft) thick. “The upper grade of this formation is about 85% calcium carbonate, but the lower part, which is the bottom 10.6 to 12.2 m (35 to 40 ft) is as high as 97-98% calcium carbonate,” explains Walter Lee Meech, the founders’ son, and current president.

The Clean Coal Technology Program, established in 1985 called for greener power generation nationwide. For older coal-fired power plants, this included installing scrubber systems in the smokestacks to filter Sulfur from the exhaust. Fortunately, for C&E Concrete, limestone absorbs Sulfur and fine particulates from the air, significantly reducing the environmental impact of coal power plants. “That’s what makes it such a valuable commodity,” adds Meech.

The push toward cleaner energy opened up a window of opportunity, says Meech. C&E purchased the 1,600 acres (647.5 ha) property and set up full-time quarry and crushing operations.


What lies beneath

It’s not just in the power station where the limestone is a valued addition. Milled limestone, often referred to as ‘rock dust’ is an additive used for safety in underground coal mines. Recently, C&E Concrete began supplying an ultra-fine grind of rock dust to coal mines to improve the air quality for miners and reduce the risk of explosions caused by suspended particles of flammable coal dust in the air. “We can produce 15 to 18 tonnes (17 to 20 tons) of rock dust per hour,” Meech adds.

Quarrying limestone is not without its challenges. Towering at an elevation of 2,286 m (7,500 ft) above sea level, the Tinaja pit is steeper than other mines in the region, with 21% grades at the summit. The high-pressure environment is also dusty, causing additional wear and tear on machine engines and bearings.

To withstand the harsh environment, C&E Concrete needed suitably high quality machines to support its growing demand. The company has built up its fleet so that it now includes 18 Volvo machines. This equipment has been supplied by local dealer Golden Equipment based in Albuquerque and span the size classes; comprising six articulated haulers, ranging from 25 to 40 tonne payload capacity, an L350F wheel loader and excavators – that together move more than 3,000 tonnes (4,000 tons) of rock each day.

Fueling the future

The Volvo articulated haulers are used to haul stone from the mountain down to the crusher. To keep the operation running at full capacity, the machines are fitted with 100% differential locking on all wheels and powered by the premium Volvo engine, delivering high-torque at low rpm.

“We found that Volvo haulers are stronger and the braking systems better,” says Meech. “We tried competitor haulers, and they could not hold the loads on the hill; the trucks wanted to roll. The Volvo haulers do not do that.”

Joining the haulers is Volvo’s largest wheel loader – the L350F. As the primary loader for the haulers, the L350F is fitted with a 7.6 m3 (10 yd3) spade nose bucket that carries an average of 11,900 kg (26,190 lb). Purchased in 2015, the hauler is the most recent addition to the fleet and is already earning its keep – averaging fuel savings of 180 to 227 liters (40 to 50 gal) per day.

Ensuring the machines continue to operate at optimum levels is Flavio Salazar, the account representative at Golden Equipment, who is proving as reliable as the machines itself. “They’ve been real good at taking care of us,” says Meech. “They come out when we need them and they understand what our needs are.”

Ed Morlan, crusher superintendent at the Tinaja pit, acknowledges that a solid foundation is built on durability and aftersales support. “We have equipment here with almost 40,000 hours and they’re still running,” he says.

The Tinaja pit also supplies an assortment of C&E Concrete sub-companies, whose products include ready-mix concrete, asphalt, crushed stone, gravel and sand.

The company’s growing operations at the Tinaja pit will not only produce safer and cleaner products but will also ensure a greener future. For every acre that C&E Concrete work, it reclaims another acre through a replanting project. “It’s our way of making sure that when we do business, we do it in a manner that ensures future generations can enjoy that land that’s given us so much,” says Meech.

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