Halfway around the world exists a quarry where there is no drilling or blasting. Here, 1,000 years of floodwater has filled ancient wadis with huge quantities
Halfway around the world exists a quarry where there is no drilling or blasting. Here, 1,000 years of floodwater has filled ancient wadis with huge quantities of rubble and boulders. It is mining made easy.
A wadi is a dry or only occasionally wet channel, often carrying rain runoff from violent thunderstorms. They are also referred to as washes in the Southwest United States. Some steep-walled wadis have the potential for flash flooding, resulting from rains only a few miles upstream, or as far as 60 miles away. The flood front can move down a wadi as a wall of muddy water traveling at more than 20 mph, bringing with it silt, sand and rocks. Wadis range from small gullies to broad valleys to deep canyons. The Grand Canyon is, in fact, a big wadi.
The stones that get deposited tend to be of similar size and the unconsolidated fill in the wadi channels can usually be easily dozed and harvested. The stones can be scooped up and either used as they are or further crushed. This is a recipe for quarrying made easy, but one only recently seized on in the Sultanate of Oman.
Oman is a country about the size of Kansas. It neighbors Saudi Arabia and rests between the Persian Gulf and the Arabian Sea. Before the 1970s, major quarries didn't really exist in any great number. Houses in the region were built using mainly natural stone and mud. Since then, concrete construction has taken over almost the entire market, and the money lying on the ground has been scooped up by enterprising contractors.
One such contracting firm is the Salem Mohiyaddin Bin Saif & Bros. Trading and Contracting Company. Based in the busy port city of Salalah in the southern Dhofar region, it is still dominated by its energetic 66-year-old founder.
Salem worked in Saudi Arabia for 20 years before returning to Oman in 1972 to establish the company with his three brothers. Between them they had 25 sons ó the perfect start for a growing business. The company still has more than 30 family members working in the 500-employee organization. In the early days of working in the wadis, manpower made all the difference ó as the rocks were literally picked up by hand. The stones were then dumped into a grizzly and segregated into different sizes.
As the company grew, old wheel loaders, dozers and crushers quickly replaced manpower. Much of this growth was driven by the rapid development of the port city, a duty-free zone that still attracts cargo ships to stop there instead of sailing into the Persian Gulf.
The company now quarries the wadis within a radius of about 25 miles. The government is starting to restrict wadi-dragging licenses, as they represent the country's environmental heritage and local people are fiercely protective of their surroundings. This is forcing Salem's company to dredge the more difficult sides of the wadis to extract the 500 tons per hour that the crusher can handle. This is putting pressure on the equipment used.
Salem's company has diversified into making concrete block, producing 50,000 blocks per day and dominating 95% of the local market. It also has a ready-mixed concrete operation, with a fleet of 30 trucks supplying the local area. These two businesses are a good fit with the core quarrying operation; 40% of the aggregate produced is used for the group's own purposes. It has supplied more than 1,500 tons of aggregates to the massive extension of Salalah's port.
The rapid development of the area ó and the resulting increased demand for aggregates ó has exposed the weaknesses of the previously used equipment in the quarry operation. The loaders Salem was running were more than 15 years old.
ìWe had to invest in new loaders, but had no idea what to buy,î says Hafeedh Bin Aqeel Mohiyadding Saif, the company's managing director and Salem's nephew. He is a graduate of civil engineering at Miami University. ìFriends told us that we could pay less, use less fuel and do more with Volvo equipment. I went to see them in action in a similar application and bought eight Volvo L180E wheel loaders.î
According to data published by the Central Intelligence Agency, Oman produces nearly 800,000 barrels of crude oil per day. Since the nation only consumes 60,000 barrels per day, you wouldn't expect high fuel costs. Yet, that's just what they have.
The new loaders use only 47.6 gallons of fuel per day, says Hafeedh. This compares with 105.7 gallons per day for the old loaders. Fuel prices have risen 45% in the last year, making fuel an issue even in the petrol area of the Gulf, he says.
ìThe old machines are bigger and need only six buckets to fill the trucks whereas the Volvos need eight,î Salem says. ìBut Volvos fill their eight buckets in a shorter time so the cost per ton is lower.î
The old loaders, with their greater weight (40 tons) are good when needing to push into a bank of the wadi, but their age was counting against them, as fuel efficiency is poor, spare parts were becoming harder to find and the cost associated with keeping them running was escalating. Consequently, they are in the process of being disposed.
While the mechanics seem largely indifferent as to which brand is chosen, the operators like the newly arrived Volvos. Operators can preset the boom so it stops at the optimum dump height for the trucks being used. When the operator flicks the switch the boom rises to the right level automatically. Similarly, the boom's upwards travel is constant, no matter what the throttle applied. This means that operators don't have to over-rev the engine to lift the bucket, which reduces fuel consumption and maintenance and increases engine life.
Most of the information for this story was provided by Volvo.