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SJ Crushing is a privately owned Perth based organisation that contract crushes for Western Australia?s mining and quarrying markets. It was first established in 2005 as a designer, constructor and operator to Aztec Resources? Koolan Island iron ore crushing plant.

In 2010, SJ Crushing submitted a tender to contract crush at Kimberley Metals Group?s Ridges Iron Ore Project. The project involved the crushing of mined iron ore from a surface miner to export quality iron ore in grades based on sizes of 0-10mm and 10-30mm. SJ Crushing collaborated with Wirtgen Australia and Kleemann to determine the machines required and modelled the proposed system in the AggFlow crushing and screening simulation program.

The SJ Crushing submission was to use four crushers: a Mobicat MC 125 Z tracked jaw crusher as a primary crusher and three Mobicone MCO 13 S tracked cone crusher triple-deck screens. These would be interlinked to operate together. The outputs from the three cone crushers would be deposited onto a conveyor system that stockpiled the crushed ore.

SJ Crushing won the tender in early 2011 and placed orders for the MC 125 Z and two MCO 13 S machines. The first MCO 13 S was ordered in 2010 in anticipation of winning the tender. Due to delivery times for the machines, a Mobicat MC 120 Z was purchased. The first two Kleemann crushers were delivered to site in April 2011 and commissioned by engineers from Wirtgen, Kleemann and SJ Crushing. The commissioning process also involved in-depth operator training.

{{image2-a:r}}When the MC 125 Z was delivered in July 2011, the MC 120 Z was relocated to the SJ Crushing hard-rock quarry at Tom Price, where it is performing admirably. Wirtgen and Kleemann?s engineers returned to commission the MC 125 Z and two more MCO 13 S machines and train operators. The last two MCO 13 S machines were delivered and commissioned in September/October 2011. Wirtgen Australia and Kleemann engineers have made several follow-up visits to adjust the machines and provide further training and support to SJ Crushing.

The final set-up consisted of the MC 125 Z being fed the mined ore with a 990 loader fitted with a 10m3 bucket. The ore is mined by a surface miner, with some material being blasted. The MC 125 Z breaks the ore to minus 120mm. The output from the MC 125 Z is fed into the first MCO 13 S, acting as a secondary crusher.

The MCO 13 S is a unique machine that combines a 299kW cone crusher with a triple-deck screen and a recirculate conveyor. The MCO 13 S feed material is passed over the triple-deck screen with the oversize fed into the crusher. Material passing through the screen is either diverted to the second (or tertiary) MCO 13 S or (if undersize) to the finished product stockpile conveyor. The oversize material is crushed and returned to the feed hopper for recirculation to the screen.

The tertiary MCO 13 S operates the same way, with oversize material going to the crusher, mid-size to the third (or quaternary) MCO 13 S and the undersize material fed to the stockpile conveyor. The third MCO 13 S crushes all remaining material to 10mm, with any oversize recirculating for further crushing.

The four machines take ore that is sized at 0-800mm, then crushed and screened to get a primary 0-10mm product and a 10-30mm product when required. The machines are operated for up to 15 hours per day, seven days per week. Typically, SJ Crushing will operate three machines, with the fourth, an MCO 13 S, undergoing maintenance. The output from the three machines, comprising an MC 125 Z and two MCO 13 S units, is 400 to 500 tonnes per hour. With the three machines in circuit, processing rates up to 850 tonnes have been achieved in an hour.

A major challenge was the distances involved. The Ridges Iron Ore Project is 150km south of Kununurra, 3000km from Perth, 1000km from Darwin and in a remote part of Australia with limited air and road services. Kimberley Metals Group and SJ Crushing staff work there on a two weeks on, one week off roster. Wirtgen Australia and Kleemann engineers worked on-site for up to four weeks to commission and train staff.

SJ Crushing managing director Steve Crabbe was impressed with the Kleemann machines because they produced crushed product at a rate far beyond expectation. He says SJ Crushing intends to buy more Kleemann machines as the company grows.

Source: Wirtgen Australia

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