National Quarries LLC was founded in Siji, Fujairah in the United Arab Emirates in 2002. The company is today considered to be one of the leading aggregate suppliers in UAE with approximately 150 employees, and an annual production of 3.5-4 million t of high quality aggregate which is produced in a variety of sizes. The products produced are supplied to construction and readymix companies in the UAE and the surrounding area.
In order to produce the large amount of accurately sized aggregates demanded by the local construction and readymix industries, National Quarries use a three stage crushing process. This consists of a 42 x 48 inch jaw crusher as a primary; a cone working as the secondary crusher, and two impact crushers operating in a tertiary capacity. The existing crushing plant was doing satisfactory work, but the company’s management felt performance was lacking. This led the company to approach Sandvik Construction Middle East which offered a modern solution using a CH660 cone crusher (Fig.).
In order to be able to propose the best solution possible for National Quarries, Sandvik was able to use the PlantDesigner© simulation tool. Sandvik Middle East’s Ashwin Prajapati says: “We checked different scenarios, changing different machines and our findings were quite interesting. It was correctly so that the secondary cone crusher was a bottle neck in terms of capacity, but also the reduction ratio was quite poor which led to a coarse feed to the tertiary impactors and an unnecessary amount going in closed circuit over the impactors.” Using the PlantDesigner© simulation tool enabled Sandvik to propose a simple and cost effective solution. “We could see that by changing the secondary crusher to a Sandvik CH660, not only would increase the throughput in the secondary stage, but also the net production in the impactors would increase due to the decreased percentage going in closed circuit,” says Prajapati.
In 2013 National Quarries replaced its existing cone crusher with the CH660. “The total capacity of the plant has increased by 25 %. The output from the old cone crusher was around 0-75 mm, while with the CH660 we are able to reduce the output to 0-63 mm. This has led to a reduction of the close circuit on the tertiary impactors, resulting in increased life time of the wear parts in the impactors by 65 %. We are also using 20 % less fuel in our generators due to less power consumption. On top of that the 0-5 mm production, which is a less valuable product, has decreased about 5 %,” says General Manager of National Quarries, Thair Aziz Muslem.
In the beginning of 2015 it was time for National Quarries to invest in a new crushing plant, and due to the success of the CH660, Sandvik was the favored company to supply the new plant. In May 2015 National Quarries placed an order with Sandvik Middle East for one CJ615 jaw crusher, two CI532 impact crushers, one primary feeder and three product screens for its new crushing plant.