In business since 1985, the New South Wales-based Nepean Conveyors group has grown significantly in recent years, with turnover in 2001-02 expected to reach $160 million. Originally focused on the design of components for underground coal conveyors, Nepean now offers a complete conveyor system, from desktop design through to turnkey installation. There is probably not a single longwall mine in Australia that doesn’t have some Nepean equipment, whether it be driveheads or belt storage equipment.
Nepean further extended its capabilities last November via an agreement with conveyor guru John McCallum. The alliance was formed to develop a line of idlers, through subsidiary Nepean Meco Conveyors.
Currently the market for idlers and other conveyor structure is dominated by a handful of players, including Prok Group and Continental Ace. In the first five years Nepean hopes to corner 10% of that market, and a further 20% in the subsequent five years.
One of the most exciting projects Nepean has underway at the moment is the coal clearance upgrade contract for the United mine in NSW. Previously a bord and pillar operation, the Enex Resources-owned mine is undergoing conversion to longwall mining ahead of a scheduled May 2002 start-up.
The contract involves a drive upgrade comprising pulleys, 400kW belt optimum soft slave (BOSS) transmission power modules and 500kW variable voltage variable frequency power modules, sub-station and controller assemblies.
Trunk conveyors will be upgraded from a capacity of 2000 tonnes per hour to 3200tph and maingate conveyors to 2200tph.
Nepean managing director, Peter Gilbert, believes the upgrade is a world-first in the application of advanced conveyor technology. The package includes a dual 500kW maingate host drivehead starter controller coupled with a regenerative triple variable frequency (VF) tripper driver.
The installed system will have a power rating of 2MW with 1MW at the VF host drive and 1MW on the tripper, which Gilbert said has never been done before.
The VF technology allows the conveyor to run at variable speeds at 100% torque and power, depending on what stage mine production is at. When only development coal is on the belt the speed can be reduced from 4m per second to 1.5m/sec, effectively increasing belt life by about a third. The system features 100-second start ramp-up and a controlled power-down on a normal stop. With the ability to better control starting and stopping, reaction time of the loop is not as critical.
Crucial information such as motor currents, belt tensions, proportional voltages, belt speeds and working pressures is essential in tripper assisted systems, and is collected by Nepean’s CPU for trending and diagnostic purposes.
The United contract also includes nine 400kW BOSS transmissions units on the outbye and drift belts. The BOSS technology permits load sharing between tripper drives with the result being that belt length can be doubled for roughly half the cost of duplicating services on each drivehead.
According to Gilbert, BOSS technology provides benefits over other scoop fluid couplings, such as faster and more accurate response to control change, less power losses due to viscous friction clutch and no critical alignment issues.
The system is suitable for high production conveyors (5000tph at 2m belt width) and provides precise power control on head drives, tripper drives and linear boosters.
Other recent orders include triple 630kW CST tripper drive controlled start transmission assemblies for Moranbah North, and 1.5km of Nepean Meco Conveyors idlers for the Oaky No.1 trunk upgrade.
Meanwhile, group subsidiary Nepean Conveyors South Africa has been awarded the coal clearance system for the Matla 2 mine. The contract is for eight conveyors, 28 BOSS modules and 1650mm wide belts. The system’s capacity will be 4500tph with “flooding” capacity for 5800tph.
Some 235 BOSS units have been installed at over 14 mines around the world, including South Bulga, Wollemi, Cumnock, Southern and Baal Bone in Australia.
