ACTOM Industry achieved a “first” in December last year by completing three large mine winder upgrade contracts during that brief period.
The multi-million rand contracts were for Anglo American Platinum’s Amandelbult mine near Thabazimbi, Limpopo Province, Harmony’s Moab Khotsong gold mine in Orkney, North West, and Sibanye Stillwater’s Kloof mine in Carletonville, Gauteng.
“Having all three contracts close to completion at the same time is an unusual occurrence. We saw it as an opportunity we couldn’t afford to miss to set out to complete all three by taking advantage of the mining industry’s end-of-year shutdown to do so,” said Janna Kapp, ACTOM Industry’s General Manager.
“But to do so successfully meant having to carefully plan and coordinate all the work required across the three contracts to ensure that they were completed without a hitch. We found this very challenging at times, since in some cases senior team members were required to work on more than one project, necessitating having to reschedule procedures to ensure that the times when these specialist technicians and managers were needed didn’t clash,” he explained.
The three contracts were:
- Amandelbult’s Tumela shaft DC rock winder power equipment and control equipment upgrades. This contract was awarded to ACTOM Industry in December 2020.
- Moab’s Khotsong shaft’s DC dual-purpose (man/rock) winder control system upgrade, awarded in October 2020.
- Kloof’s Manyano sub-vertical shaft DC rock winder control equipment upgrade, awarded in May 2021.
All three contracts comprised upgrading of obsolete electronic equipment that had been originally designed, supplied and installed by ACTOM Industry in conjunction with its Europe-based principal at the time. In all of the upgrades the high capital value existing original DC winder drive motors were retained coupled to the original retained mechanical equipment.
The Tumela rock winder scope included an upgrade from a Ward Leonard system (M-G set) to a modern thyristor-controlled drive. The static (or solid state) thyristor-controlled DC drive upgrade eliminated the inefficiency and routine maintenance of the rotary M-G set, which it replaced.
All three upgrades included a new ACTOM Q closed-loop drive regulation and control system. The control system is a state-of-the-art distributed control system using ether CAT to communicate to distributed I/O nodes from a central IPC. The host IPC microcontroller executes the control sequencing and safety logic of the winder system. The new regulation system offers the most modern upgrade/retrofit solution from analogue and older digital controllers. The closed-loop regulator provides true torque control and prediction and a number of feed-forward torque signals which ensure ideal control of the winder.
The Moab Khotsong control and regulation upgrade also included a closed loop brake control system upgrade. ACTOM Industry was the original pioneer for closed-loop brake control electronic systems in Southern Africa and numerous systems have been successfully supplied for high production hoists from deep levels since the early 1990’s.
Closed loop brake systems are used to reduce the strain on winder ropes during emergency braking conditions. This is achieved by a smooth transfer of torque from the electrical drive to the brake system. The speed and retardation rate of the winder drums and conveyances are accurately controlled and shaped during emergency stopping. This reduces the dynamic rope loads, thereby making deeper winding possible and extending rope life. Independent control units control independent brake units/channels to enhance the reliability and safety of the braking system.
