Sibanye Gold

Background

Sibanye purchased a number of mines, each of which had evolved their own solution to the power management problem over many years. In fact, all these solutions added up to no less than 39 stand-alone applications across the company’s operations.

“Multiple energy control projects at the different operations resulted in many proprietary third-party systems being used for scheduling,” says P.J. Jansen van Rensburg, ICT Manager, Networks and Engineering Systems, Sibanye. “Any energy control schedule configuration was done in isolation of the others and their inflexibility caused some contradictory control problems such as different priorities seen from the perspective of the solution vendors – even at the same site. This resulted in management not having access to all applications and their information.”

But the problems didn’t end there. Sibanye’s production activities were not synchronized with Eskom’s tariff structures with regard to load shifting (moving the load demand to non-peak times) and load clipping (limiting the load to set limits). And lastly, there was no standardisation across all 32 SCADA systems in use at the time.

“We chose a decentralised infrastructure model, which meant that, in the event of a hardware failure, only the local site would be affected while each Sibanye operation, shaft and PLC would be able to run independently in case of a communication failure,” says van Rensburg. “The solution that ticked all the boxes was Wonderware’s System Platform.”

“To better understand what the total power control module needed to do, it’s important to understand Eskom’s two-part tariff system,” says van Rensburg. “This consists of Load Shifting which means scheduling machinery to either stop working altogether or run unloaded during Eskom’s peak periods (18:00 to 20:00 in summer and 17:00 to 19:00 in winter – 2.5 times the rate for non-peak consumption). Then there’s Load Clipping which is done by unloading machinery during Eskom’s peak and standard tariff periods as per set targets.”

So schedules were created, configured and activated to cope with Load Shifting while targets were set and algorithms created and deployed to handle the Load Clipping aspect of power control. “Because of its real-time nature, we still can’t do Load Clipping during network failure,” explains van Rensburg. “But Load Shifting is no longer a problem because a register for the next 20 operations is programmed into the PLC every few seconds which means that it can continue to independently shift loads for up to a week if necessary.”

“Standardisation is crucial to operator efficiency it they change plants but it also provides a standardised communication ‘language’ and understanding between everyone involved who all have access to this production information. This lets them benchmark and compare their accomplishments to other plants because they all share a common standard for performance,” says van Rensburg.

Sibanye owns and operates high-quality gold and platinum operations in South Africa – consolidated into one Group with one vision and strategy. The long-term success of Sibanye as a business and as a responsible corporate citizen is dependent on all stakeholders working together as one.