iC reports on the exact science of making aggregate production pay.

The need for accuracy to achieve optimum productivity is driving the way quarries are operated. iC reports on the exact science of making aggregate production pay.

According to Arvid Svensson, business development manager at Sandvik Mining and Construction, the key aspect of quarrying is finding the optimum solution between what to do in the drilling and blasting stage and what to do in the crushing and screening plant.

"First, one has to drill and blast the rock and in that fragmentation process you create fine material, sand and coarse rock," Mr Svensson told iC. "It's important the drill and blast and crushing and screening phases are designed to complement each other so you don't create material that you cannot sell. It's not about making the maximum; it's about making the optimum."

Precision drilling therefore represents the starting point for the entire process. In this respect, Atlas Copco unveiled its ROC T35M surface drill rig in June, designed specifically for drilling high quality holes efficiently. "Every contractor dreams of higher penetration rates, straighter holes and better accessory life," said Bo-Goran Johansson, vice president of marketing at Atlas Copco Surface Drilling Equipment.

"The next generation ROC T35M drill rig is modular in construction, using parts common to the Atlas Copco surface crawler range for ease of use and maintenance, while improving productivity, cost-efficiency and quality," said Mr Johansson."

Sandvik meanwhile launched its new RT300 drill bits this year, designed for use with big tophammers to cut through aggressive rock formations. "Manufactured from a new super-grade of cemented-carbide called XT48, and featuring a universal face design, the buttons on the RT300 are stronger and more wear resistant than anything before," Mr Svensson told iC.

"Combining our hard materials technology with more effective cutting structures, greater rigidity and good flushing ports, the Sandvik RT300 drills straight, clean holes up to 152 mm in diameter while using only half the fuel of down-the-hole alternatives.

Movement

Following blasting, the onus is very much on material handling. Wheeled loaders are the main product working in a quarry according to Håkan Gustafsson, global product leader for wheeled loaders at Volvo. "No other machine can compete when it comes to material handling because of the versatility of a wheeled loader.

"Of course, productivity and lower fuel consumption are what give our customers their income and lower their costs, so these are the areas that we concentrate on at Volvo."

A high profile example of this drive for efficiency is Volvo's hybrid wheeled loader which Mr Gustafsson said, "was received enthusiastically by the market. It's a new product area and we have to be very careful that we are working to meet our customer's demands, but I do think it's the most significant product of the past 12 months."

Earlier this year, Komatsu launched its WA500-6 wheeled loader for handling blocks up to 27 tonnes. The WA500-6 features a heavy duty quick coupler, a reinforced frame and a large capacity torque converter. Options include an axle oil cooling system and a sequential torque converter lock-up, which improves fuel efficiency and productivity, especially when climbing up hills.

Powered by a 263 kW Komatsu ECOT3 engine the WA500-6 has a lifting height of 1.5 m and is ideally suited to the heavy weight demands of quarrying.

Also this spring, Caterpillar dealer Bergerat Monnoyeur fully rebuilt a 994D wheeled loader that had clocked-up 48000 hours of service in the Carrieres d'Antoing quarry, near Tournai, Belgium.

The 193 tonne machine - known as the Barbarian - has worked at the quarry since 1993 and this year's rebuild follows a 24000 hour revision back in 2002.

Eight technicians took more than three months working on the 17 m long, 5.5 m wide and 6.5 m high loader and amassed 5000 hours of labour to carry out the rebuild, which included disassembly, reworking and then rebuilding from scratch, including the fitment of a new engine. "The technology was updated to the latest state-of-the-art systems, which should extend the life for up to another 20000 hours," said a Caterpillar spokesperson.

"Even with the parts and labour costs taken into account, the cost of the rebuild was lower than buying a new machine. Considering the underlying economic conditions, the rebuild was a good option," said the spokesperson.

On the European-Asian border in Turkey, Hitachi is enjoying growth in its market share in the wheeled loader sector. The company entered the country in 1980 with ENKA Pazrlama as its distributor and by 2007 annual sales of Hitachi wheeled loaders exceeded 100. This, along with excavator sales of 800 units means Turkey is an important market for the manufacturer.

"The importance of Turkey has now grown to the extent that it has become a key testing ground for engineers from Hitachi, who regularly travel over to test and modify existing machines," said Paul Burger, international sales manager at Hitachi Construction Machinery Europe. "The tough nature of the working conditions and the long operating hours help them to assess the performance of tomorrow's technology in the field."

"Our ZW wheeled loaders have proved popular because of their high productivity and low fuel consumption," Mr Burger told iC.

Emissions haul

While versatility is key to Volvo's wheeled loaders, it's also an integral feature of the company's articulated dump trucks (ADTs). "We're seeing an increase in the number of ADTs in quarry operations," said Mr Gustafsson. "They are quieter than rigid haulers and more versatile."

Per Erik Bergqvist, market and project support manager for Volvo Haulers told iC, "The challenge for everyone is to try to add customer value alongside meeting legislative requirements. The new emissions legislation is really driving the industry at the moment, because they are harsh demands and they require significant technology development and resources."

Kevan Dowse, marketing director at Case echoes the point. "The most significant development relating to haulers is emissions legislation. Using engines from Fiat PowerTrain has been a great advantage to us."

"The big challenge for all ADT manufacturers is compliance with Tier 4 Interim legislation in 2011," said Harry Stuart, design manager at Doosan Moxy. "We are looking at two solutions and will select the one that offers the best balance of economy, serviceability and availability."

Aggregates

The development of mobile crushing and screening equipment has transformed quarry life, yet the aim remains the same as with big static facilities. "The key is to produce what you can sell," Mr Svensson told iC. "In some parts of the world people will pay US$ 50 per tonne for sand, while in others sand is considered a pain and has no value.

"If you produce one million tonnes per year and you can produce -1% less waste material then you gain big savings both through a greater quantity of saleable product and also less waste material to dispose of. Also, that 1% cost the same amount to drill and blast and screen, yet it created no value."

Mark Hezinger of Kleemann said, "Whatever crushing and screening system a quarry operator adopts, there must be a guarantee that top-quality end products, with regard to cubicity and output, can be manufactured. Furthermore, the process must be reliable and economically worthwhile."

Match

Accurate matching of processes and equipment dictates the productivity and therefore the profitability of a quarry. Or as Mr Svensson put it to iC, "If you don't excel in all areas, you will not excel as a quarry."