New 4200 SM: Productivity is its trademark

Cloudbreak is a gigantic mining operation run by the Fortescue Metals Group in the Pilbara region in the north of Western Australia. The iron ore mining site covers 40,000 km² and is approx. 2.5 hours by air from Perth. The entire project is an amazing feat of logistics: some 8,000 people work here, shuttling to-and-from the mine during shift change on a charter flight with Skywest Airline – just like other people commute to work every morning on the bus. A residential and administration camp comprising a huge collection of prefab huts about half an hour‘s drive away provides the workers with all of their daily necessities. In addition to Cloudbreak, FMG is currently developing an additional mining facility some 40 km away at Christmas Creek.

43 high-production surface miners of the types 4200 SM and 2500 SM mining iron ore in Australia. The deposit was designed for use of the surface mining technology right from the start.

43 high-production surface miners of the types 4200 SM and 2500 SM mining iron ore in Australia. The deposit was designed for use of the surface mining technology right from the start.

Recipe for success: selective mining

Taking stock of the mining operation since its commencement in May 2008, it is soon evident that the use of Wirtgen surface miners as the primary mining equipment in this project has truly paid off. The structure of the material, the hardness of the rock and the entire terrain provide ideal conditions for costeffective exploitation of the opencast deposits using the selective mining technology of Wirtgen. Comparisons of various mining methods for the flat structure of the opencast iron ore deposits commissioned by FMG clearly favoured surface mining, instead of conventional mining methods using drills and explosives. Wirtgen miners have been put to the test for 20 years now in soft rock, such as coal, and in hard rock like limestone or granite – rock that is ten times harder than the average iron ore found at Cloudbreak. FMG directly exploited the advantages of the surface mining technology at Cloudbreak to mine crushed iron ore more cost-effectively. The recently arrived 4200 SM has also provided impressive evidence of its worth as a production machine. The benchmark for the high-performance giants from the Wirtgen product line is an impressive daily output of 12,000 tonnes, all in a single shift. The major challenges posed by the project are the varying degrees of hardness of the rock in the pits and the need to operate a seamless logistics chain and to ensure that the loading capacity of the dumpers is high enough for them to cope with the surface miners‘ high production volume. Equipped with a special cutting drum assembly for hard rock, the 4200 SM arrived at Cloudbreak in early August after a 26 hour overland journey. Wirtgen service technicians Rainer Salas and David Möhlmann were already prepared and waiting in the early morning. Thanks to their know-how, it took just four weeks for the colossal machine to be assembled and tested and the FMG crew to become familiar with operating it. The 4200 SM was put into regular operation in September, allowing everyone to adjust to the new machine, from the operators and logistics crews, all the way to the service crew for the miner, which is responsible for the continuous maintenance of the specialist mining machine.

4200 SM: pure performance

With the 4200 SM, FMG made a real quantum leap in performance and productivity. While the 777 series dumpers from Caterpillar with a loading capacity of 100 tonnes are still adequate for the 2500 SM miners, FMG has had to acquire Type 789 mining trucks for the new Wirtgen giant, with almost twice the loading capacity at 195 tonnes. The 4200 SM can load one of these trucks in just four to six minutes, depending on the hardness of the material being mined. The new machine also quickly became a favourite among the operating crews, who were only too keen to get to grips with the 4200 SM. The cab of the new miner provides the operator with an improved overview of all relevant working areas and all-in-all a more comfortable work station thanks to lower noise levels and protection from dust and vibrations in an ergonomically designed operator‘s cabin.

Smart material distribution

The „Automatic Positioning System“ installed by FMG is a highly intelligent instrument for controlling the distribution of the cut material rapidly and selectively. To this end, geologists calculated and developed a model of the opencast deposits. This was then converted into a digitized map that is transmitted to the surface miners wirelessly. This allows the operator of every surface miner to see the position of his machine and the quality of the material that has just been mined on a display in the operator‘s platform. The machine operator then radios the information on the cut material to the dumper driver, together with the location where the material is to be unloaded. The different grades of iron ore are finally selected from the various storage sites and mixed according to the desired composition. In this way, the principle of selective iron ore mining with the Wirtgen miners is also implemented 1:1 in the subsequent material distribution phase, in order to comply with the high demands of FMG on quality. Another aspect of the principle is the potential savings in time and costs, as the mined material ends up at the right unloading or processing point without any further interim steps. Depending on the moisture content, the material is stored in stockpiles to dry, or fed directly into the further processing chain on site. Material that cannot be utilized is either stockpiled as overburden or used as material for routing operations inside the mine.

Operating site: Cloudbreak, in the Pilbara region in the north of Western Australia

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