Newmont is expanding its gold mine in Western Australia – and FLSmidth Conveyor Engineering supplied the conveyor belts in a project involving 3,700 tonnes of fabriacted steel and 11.5 kilometres of belt.
The Boddington Gold Mine Expansion Project promises to make this mine, which started production in 1987, the largest of its kind in Australia. When fully operational the mine will produce around 1,000,000 ounces of gold each year. An open cut mine with two large pits, it needs plenty of conveyor belt – and FLSmidth Conveyor Engineering (FLSmidth CEI) designed, manufactured and completed the job.
The conveyor design includes 15 conveyors and 17 belt feeders with belt widths ranging from 450mm to 2,400mm and conveyor lengths from 16m to 2,172m – all adding up to a total of 11.5 kilometres of belt.
Ensuring timely delivery
By the end of the project, FLSmidth CEI had supplied a total of around 3,700 tonnes of fabricated conveyor steel to site – and to ensure timely delivery, FLSmidth CEI chose to share manufacturing between two Western Australian companies. However, both companies were using the same painting contractor, so it required careful project management to avoid a bottleneck.
Also, other steelwork for the mine was being manufactured at the same time – and this placed a lot of stress on the local steel industry. FLSmidth CEI wanted to source as much equipment and steel as possible locally, but decided to source some equipment, including drive motors and gearboxes, from overseas.
The full circuit
The ore is blasted in the open cut mine, loaded by power shovels onto trucks, and then dumped into the two underground primary gyratory crushers. The conveying circuit starts below the gyratory crushers. A 2.2 metre-wide acceleration conveyor carries the primary crushed ore through a tunnel, and drops it onto the overland conveyor. At 1.8 metres wide, the overland conveyor has a capacity of 8,000 mtph and runs for 2,172 meters with a rise of 120 meters, dropping the ore on a 40 metre-high stockpile. Twin 2800 kW motors drive the conveyor at almost 4.5 meters per second, and it has a creep drive arrangement for maintenance purposes.
The ore is reclaimed from the stockpile by three apron feeders – and is then carried on a 2.2 metre-wide conveyor, with a shuttling head, to the coarse ore bins. These bins feed onto five 2.4 metre-wide belt feeders that supply material to the five secondary cone crushers.
This second circuit has a capacity of 7,300 mtph. The reduced material is passed through screens, and the oversize material is fed back through the cone crushers, while the undersized material is taken to a surge bin by another shuttling head.
The surge bin supplies four 2.4 metre-wide belt feeders, which feed four HPGR crushers. Material from the crushers is carried 66 metres to the fine ore bins on a tripper conveyor with a capacity of 10,500 mtph. Sitting below the fine ore bins, four pairs of 2-metre wide belt feeders supply the four ball mills. The crushing media for the ball mills comes from a high-angle conveyor – and the tramp metal is removed from the fine ore circuit by a 450 millimetre-wide belt conveyor.
The entire conveying circuit has safety guards and other safety devices, including belt rip detection, belt slip detection and plugged chute switches, as well as metal removal magnets, moisture analysers, belt scales and image analysers.
It’s also extremely maintenance friendly. There are a number of overhead cranes and monorails, as well as belt scraper removal trays and a unique pulley removal system. Also, all counterweights inside the transfer towers have their own winch and tie-off chains for maintenance purposes – and a maintenance cart makes removing and installing the large drive assemblies inside the transfer towers simple.
At its peak, the onsite workforce totalled over 3,500 people, representing something of a boom for the town of Boddington. Around 2,500 workers were housed in a camp next to the mine, and a fleet of buses ferried the other workers in and out of the site.
The final plant will be operated by around 650 people, and Newmont has brought in many of its experienced mining professional from around the world to train them. The plant is currently undergoing the final stages of commissioning, and should ramp up to full production during 2010.
About the Boddington Gold Mine
The Boddington Gold Mine is located near Perth in Western Australia. It sits on the Saddleback Greenstone Belt, a fault-bounded sliver of Archaean-volcanic and shallow-level intrusive rocks, surrounded by granitic and gneissic rocks. The mine contains proven and probable reserves of over 20 million ounces of gold and has an expected life of more than 24 years. With an expected production of around 1,000,000 ounces of gold each year for the first five years, it will be the largest goldmine in Australia. Newmont is the world's second-largest gold mining company and employs around 28,000 worldwide.
About FLSmidth Conveyor Engineering
FLSmidth Conveyor Engineeering (FLSmidth CEI) specialises in designing and supplying major bulk material handling facilities – and its primary products are heavy-duty high-capacity feeders (both belt and apron feeders), in-plant conveyors and overland conveyors.
Established in the 1950s, FLSmidth CEI joined the FLSmidth Group in April 2009, and is now an integral part of FLSmidth’s world-wide operations. The FLSmidth CEI head office is located in Meridian, Idaho in the USA.