Alignment-free drives

Electrical switching & drive systems & components

4th Quarter 2011 Electrical switching & drive systems & components

ThyssenKrupp Material Handling supports a wide range of clients in large scale material handling applications, especially in the areas of open pit mining, minerals processing and bulk material handling. The company was recently in charge of a major expansion project for Lihir Gold, which is located on Lihir Island in New Ireland, a province of Papua New Guinea. The Million Ounce Plant Upgrade project (MOPU) will increase Lihir’s total annual gold production by over 30%. Bonfiglioli was chosen to supply drives for the discharge and spillage conveyors.

More than one million ounces of gold (about 28 350 kg) are already mined each year at Lihir Island. However, due to plant constraints only 600 000 to 700 000 ounces (17 010 to 19 845 kg) are processed in a year. The remaining ore is stockpiled until it can be processed in subsequent years.

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 upgrade will increase total annual gold production by approximately 6804 kg per annum from 2012 for the remaining life of the operation.

Lihir’s investment in additional processing capacity through MOPU will increase plant throughput so that it is more closely matched to mine production.

This will enable more of the mined ore to be processed, improving operational efficiencies and bringing improved returns for the company’s stakeholders.

Needs of the application

The client required the plant to operate 24 hours a day, seven days a week, 52 weeks per year. The discharge conveyors needed to have right angle bevel helical with rigid flange couplings, backstops, and fluid couplings. The spillage conveyors had to be shaft mounted gear motors with a torque arm bearing L10 life greater than 60 000 hours and the gear life needed to exceed 100 000 hours.

The Bonfiglioli solution

Extending the versatility of its series of advanced heavy duty drives, Bonfiglioli Australia’s Drive Services Centre introduced an alignment-free configuration that cost effectively integrated motor and gearbox and avoided the need for a costly baseplate.

The alignment-free design consisted of a large bell housing that contained the fluid coupling and fan and provided a standard IEC interface for the flange mounted motor. This arrangement saved time and labour during commissioning of the drive as the alignment of the transmission components had already been done. Vents cut in the bell housing allowed air from the fan to be forced along a path to provide optimum cooling for the gearbox. The bell housing had an additional benefit as it provided a collection point for fluid lost by the fluid coupling in case of a blowout.

For the discharge conveyor, two HDO110 3 24.6 LPB R1 VP B3 FAN MOP A CW TK OLG alignment-free drives fitted with free issued Teco 75 kW 4 pole motors were used. Spillage conveyor specifications were A703 US 72.5 P132 fitted with free issued Teco 5,5 kW motors.

Bonfiglioli Australia won the job by providing more benefits at a lower cost to the customer than any other contender.

An important benefit of the MOPU project 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.

For more information contact Robert Rohman, Bonfiglioli, +27 (0)11 608 2030, [email protected], www.bonfiglioli.co.za

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Alignment-free drives

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