Alignment-free drives for gold expansion project

LGL is undertaking a major upgrade of its Lihir Island gold operation in New Ireland province of Papua New Guinea. The upgrade will increase the total annual gold production by about 240,000 ounces to approximately 1 million ounces per annum from 2011.

Titled the Million Ounce Plant Upgrade (MOPU), the upgrade will involve the installation of one additional autoclave with double the capacity of each of the three existing autoclaves, as well as additional crushing, grinding, thickening, oxygen, and leach plant facilities. Grinding capacity of the plant will increase from around 6 Mtpa to approximately 11-12 Mtpa.

An important benefit of MOPU is that it will enhance operational efficiency at the Lihir Island operation and reduce sensitivities to short-term fluctuations in ore gold grade. In addition, it will reduce operating risk and increase reliability by duplicating parts of the processing chain. This will ensure the operation is a more reliable and consistent gold producer over many years to come.

ThyssenKrupp Materials Handling supports clients in large-scale materials handling applications - specifically in the areas of open pit mining, minerals processing and bulk materials handling. The company contacted Bonfiglioli to supply drives for discharge and spillage conveyors on the expansion project.

The application consists of two jaw crushing lines operating in parallel. Each line has two conveyors - one for discharging and one for spillage. The discharge conveyors have a throughput of 1200 wtph, while the spillage conveyors receive 20% of that throughput in finer ores from spillage.

The general needs of the application were for operation 24 hours a day, 7 days a week, 52 weeks a year. The discharge conveyors require right-angle bevel helical drives with rigid flange couplings, backstops, and fluid couplings. The spillage conveyors are to be shaft-mounted gear motors with torque arm bearing life to be greater than 60,000 hours and gear life to be 100,000 hours.

Bonfiglioli’s recently expanded Drives Service Centre came up with an ‘alignment-free’ input design for the Lihir project that negates the need for a costly baseplate. The alignment-free input is basically a large bell housing that contains the fluid coupling and fan, and provides a standard IEC interface for the flange-mounted motor. This type of input also saves time and labour during the commissioning of the drive, as the alignment of the transmission components has already been done. Vents cut in the bell housing allow air from the fan to be forced along a path to provide optimum cooling for the gearbox. The bell housing also has an additional benefit in that it provides a collection point for fluid lost by the fluid coupling in case of a blowout.

The Bonfiglioli HD AFD combinations - with capacities up to 1722 kW and 150,000 Nm - can save both time and money in a range of applications because there is no need to laser align the motor and gearbox shafts, says Malcolm Lewis, Managing Director, Bonfiglioli Transmission (Australia) Pty Ltd. In addition to reduced initial costs compared with traditional baseplate designs, the HD AFD configuration enhances serviceability by permitting high-speed components to be removed and replaced without the need for realignment. Applications include conveyor drives, shuttle drives, bucket elevators, inching drives and other materials handling equipment.

The HD AFD is produced in Australia on Bonfiglioli’s new production and testing line that cuts delivery times out of Europe by more than half for most models.

The HDP parallel shaft and HDO bevel helical units suit numerous mounting options, for different applications, such as materials handling, manufacturing, mining, quarrying and minerals processing, rural and food product processing, paper, pumps, steel, sugar, timber, wrapping and stacking applications, and water and wastewater treatment.