Gaining stone from a quarry is a hard way of making a living.
Production outputs have to be maintained at a constant level, and an eye must be kept on the international markets so that priority is given to producing the quarry product with the highest demand and therefore value. Obviously, the amount of saleable product must be kept to a maximum while time and money wasted through handling materials twice must be avoided at all costs.
Modern Drills
For decades, drill and blast has been the preferred way of getting rocks out from the face. Some time ago, we spoke to David Matyus, GM of equipment and consuting company Quarry and Mining said “Drilling and blasting is still the high production method.”
While the technology has remained the same, the size of the drill has increased dramatically. Early methods of drilling into rock were crude, though many times more efficient than hammering away at rock manually – as those of you familiar with the legend of ‘John Henry’ might recall. Modern drilling ‘jumbos’ attach several drills onto one hydraulically-driven mobile plant.
Moving Rocks
Ask most people what the most dangerous aspect of quarrying is the reply invariably is drilling and blasting. In fact, the overwhelming majority of accidents happen on the rocky road between the cliff face and the crusher.
Dozens of huge dumpers thundering down a steep incline, laden with hundreds of tons of rock have the potential for devastating accidents with whatever is coming the other way, no matter how well run the quarry is.
Although things are changing, some quarries still pay scant attention to the safety of the workers. Matyus said “Most of the accidents over here, and there have been some horrendous ones, have involved vehicles.”
He added “There are two extremes, some are very European in outlook and some pay absolutely no regard is paid to safety so you have got small cars driving around in areas where there are enormous trucks.” Obviously, safety begins by removing the small cars from the boulder trails and by better training the truck drivers.
However, new innovations can further improve the run down the hill. While weighing trucks has been the norm for some time, one electronics manufacturer can now supply the region with a device designed especially for articulated dump trucks. The dash-mounted device looks similar to electronic weighing machines that have been around for a while, but has been especially designed for quarrying.
While having trucks carrying the right load is a good start, both safety and efficiency can be made even better, by simply removing the dumpers altogether.
Many modern facilities around the globe have invested in conveyer belt systems instead Although they are expensive and require careful engineering at the point of installation which Matyus explained “A conveyor system is very efficient, For a start, it doesn’t need any power as the weight of the stone pulls it down the hill, so the whole thing is self generating. In fact, it needs brakes to stop the conveyor going too fast”. Large installations can see conveyors hundreds of meters long being constructed, with stone going directly to the primary crusher.
Crushing
The job of the primary crusher is to turn the rock into rubble. These machines need to be manufactured to a high quality, as they get no rest.
“A well managed plant will be running at 85 per cent efficiency, 20 hours a day” Matyus said. In fact, were it not for the mandatory downtime in the early afternoon as demanded by law in the northern Emirates, it is highly likely that the machines would simply never stop.
In the past these plants would handle a few hundred tones per hour, but now modern equipment is pushing this figure much higher, with plant such as the Kleeman SSTR 1600 unit handling up to 1200tph.
Wheel loaders
There were many large loaders on display at the MineExpo show in Vegas last year, as well as in Bauma in April, with products from brands such as Liebherr, Komatsu and LeTorneau. However our attention turned to the latest offering from Caterpillar, the 993K.
Although not available as a stock item in the GCC at the moment, the item is available by special order from the region’s dealers. The all new model offers a new size class in the Caterpillar line-up. The 25-ton capacity loader features Z-bar linkage, hydraulics and power train that deliver high breakout forces—20 percent more than the 992G.
The increased performance and capacity result in a 15 to 20 percent improvement in productivity compared to the 992G, according to the manufacturer.
The new loader at the show also features the Cat C32 ‘Acert’ engine. It produces net power of 950 horsepower (708 kW). The makers also say that the newcomer offers solutions to ease maintenance and boost reliability.
For example, the sleeve bearing pins eliminate the need for daily greasing of the front linkage. To lower life cycle costs, the 993K is designed to meet mining customer rebuild requirements and have an estimated 45,000-hour structure life.
Power train
The power train and hydraulics are designed to deliver high productivity and low cost per ton. As compared to the 3508B engine used in previous mining loaders, the C32 engine delivers 19 percent more power and a 5 percent increase in fuel efficiency. The proven C32 also powers several other Caterpillar mining machines, which simplifies parts inventory management.
The 993K features a next-generation modular radiator which has copper fins for improved heat exchange capabilities. The design and construction minimizes space required for the cooling package and allows enhanced sight lines to the rear.
Positive flow control hydraulics is the next generation of load-sensing hydraulics. Additional sensors at the pumps provide enhanced responsiveness that the operator can feel and use. The full return flow filtration system filters 100 percent of the implement oil return flow to 6 microns for extended component life and increased uptime.
The optional deluxe filtration system prevents downstream contamination in case of a failure. The Cat planetary power shift transmission is electronically controlled and features three forward and three reverse speeds.
The impeller clutch torque converter allows the operator to match rimpull to the application and underfoot conditions through the use of a foot pedal and adjustments made through the rimpull control system.
The all-wheel drive design features four planet carrier gears with planetary double reduction in each wheel. Double reduction final drives significantly reduce power train stresses and effectively extend power train life and durability.
Options for reduced maintenance include the Oil Renewal System (ORS). By regularly burning small amounts of engine oil and automatically adding makeup oil to the crankcase, ORS offers a means to reduce or eliminate engine oil changes and to increase machine availability.
Another interesting option is zip-in zip-out glass. This feature provides rubber-mounted glass, which does not require adhesives to retain the glass. The system enables fast changes of damaged glass.
Articulated Hauler
Few quarries operate without a fleet of dump trucks to take away the rubble, and a flexible and highly efficient way of doing this is with an articulated hauler. Volvo claims to have invented the concept back in the 1960s.
The current E-series haulers have a long list of features that set them apart from their predecessors including a payload of 33.5 tonnes,while the patented planetary transmission features smooth shifting providing maximum rimpull (which loosely is the amount of power the truck can transmit between the tyre and the contact patch of the ground.)
The maker says that electronic monitoring of fluid levels means enhanced reliability as well as no need for daily service. Downtime during service is short, thanks to fewer service points on a new suspension design.
A fully loaded body is raised in only 12 seconds, and lowered in only 9 seconds, while the new design of the cabin leaves plenty of room for personal items such as a lunchbox and the seat features air-suspension.
Visibility around the machine is improved even more over predecessors with the large rearview mirrors, large windscreen and windows.
Giant Excavator
Even in quarry pits, really big excavators and mining shovels are a rarity in this region. That said, there is now at least one more to chose from, with the launch of a massive new 800-ton machine at the MineExpo show, held in Vegas last year.
Liebherr announced the R 9800 mining excavator. Rated at 800 tons of service weight the R 9800 provides a nominal bucket capacity of 38 to 42 m³ at a material density of 1,8 t/m³. This new flagship of the German firm’s mining excavators’ range is targeting bucket loads of 75 tons in both versions, as a backhoe and a shovel execution.
The maker is providing for the machine two engine options, two Cummins QSK 60 with a installed power of 1,492 kW / 2,000 hp each or two MTU 12V4000 with a installed power of 1,425 kW / 1,910 hp.toughest mining conditions.
The first units of the new flagship are currently in the final stages of factory testing and the first machine is soon due for operation in Australia.
The accolade for the largest machine at the show was the Hitachi EX5500-6, which broke the record (as far as we could tell) for the largest machine ever bought to an indoor trade show, tipping the scales as it did at 570 tons. The newcomer features a choice of buckets up to 40 cubic yards, and is powered by two Cummins QSK50-C engines totaling 2,800 HP.
More recently, Bucyrus, which has now taken over Terex-Demag brought the RH200 to the Bauma show. This giant has a 50t payload capacity, an operating weight of 579t , though in this instance the machine stayed outside, performing demos for the crowds.
