Modern Quarrying April-May 2016

SAND PROCESSING AT THE QUARRY FACE

two different materials on the plant at separate quarries, as well as trial further materials brought to Whorouly from its Seymour and Mildura sites. It also illustrated to Mawsons the ease of relo- cating the plant across multiple quarry sites. According to MWS sales engineer James Murphy, who worked closely with Mawsons on the installation of the M1700 and the FM120C, the plant was moved from Mansfield to Whorouly within three days, including washdown, demobilisa- tion, freight, set-up and commissioning. Murphy says that the M1700 and FM120C can be operated independently but when the two machines are run together, they offer the “exact same wash plant in principle” as the TWS AggreSand 165, albeit on a mobile platform. “Some operators will only require rinsing of, say, crushed aggregates, and if what is being rinsed away with the water is not of value to them, they will discharge any fine material with the dirty water,” Murphy explains. “But when a client then wants to recover the sand being rinsed from the aggregates, as is the case with Mawsons, we recommend a modular Finesmaster sand recovery sys- tem sized appropriately for the tonnage/ throughput required. It’s the combination of these machines working together that becomes a wash plant, as opposed to a rinsing screen working independently.”

was nothing we could do to recover it and we were sacrificing tonnage to basi- cally recover what sand we could get. We decided we needed to look for an alternative.” Combined wash plant In 2014, Mineral Washing Systems (MWS), a subsidiary of Brisbane-based supplier Finlay Screening and Crushing Systems began importing Terex Washing Systems’ (TWS) extensive range of sand wash- ing plant and equipment into Australia, including the modular AggreSand 165. The first of these plants was installed in Dubbo, New South Wales, and at MWS’s invitation, Gilbert and other Mawsons personnel visited Dubbo Sands to see the plant in operation. They were impressed by the plant and after consultation with MWS representative James Murphy, they negotiated a six-week hire with the option to buy two pieces of TWS plant: the mobile M1700 rinsing screen and the modular Finesmaster (FM) 120C compact cyclone plant. At the time Quarry visited Mawsons Whorouly, the business had been oper- ating the M1700 and the FM120C for six weeks. The combined wash plant had spent its first four weeks at Mawsons’ Mansfield Quarry operation before being relocated to Whorouly for the next fort- night. This enabled Mawsons to test

deposit is located close to the water table and Gilbert says that as the valley gets muddy and “very clayey,” the sand recov- ery rates for the operation become more problematic. “It’s basically a river deposit and it is quite deep,” Gilbert explains. “We usually wait until November before we start oper- ating because the river level goes down and that means the ground water across the region drops.” Mawsons has employed earthmoving equipment, including a 45 t Komatsu exca- vator with a 2,2 m 3 bucket, a Caterpillar 950G sales loader and articulated dump trucks, to dig out and transport the sand deposits. It is a condition of Mawsons’ licence that it is not permitted to install and operate fixed plant on the Whorouly site. As a result, the company relies very heavily on mobile plant and equipment at Whorouly and until recently, was employ- ing a Terex Finlay 683 Supertrak rinsing screen and a dewatering screw to wash and process the sand. “We were running the sand/slurry out of the bottom of the 683 into the dewa- tering screw,” Gilbert says. “A dewatering screw is good for dewatering but it’s not good for fines recovery. It did a good job and it did what it was designed to do but because the silt and clays in this product are so low, the more water you put in, the more fine sand you wash out. There

According to Mawsons’ Trevor Gilbert, sand recovery rates for the operation become more problematic as the valley gets muddy and clayey.

After a decade of inactivity, Mawsons Concrete & Quarries reopened the Whorouly sand and gravel quarry in early 2014.

15

MODERN QUARRYING

April - May 2016