De Beers’ Venetia diamond mine was experiencing ongoing difficulties in sourcing spares for its 25-year-old Siemens S5 system used for controlling and monitoring the sorting line. Systems Automation and Management (SAM) proposed the replacement of the obsolete system with the new Siemens S7 maximised for uptime and productivity.
According to SAM’s Paul Rudolph, the older system was plagued by its ageing infrastructure and lack of redundancy. “It is a testament to the quality of the Siemens system that it has been able to operate for so long, but the time had arrived to retire the S5 as part of the plant’s ongoing upgrade programme. The S5 cards can be repaired but it is considerably more cost-effective to replace them. Together with Venetia mine management, it was decided that the transition to best practice hardware and software was desirable for optimal running of the plant.”
Upgrade philosophy and implementation
Diamonds are conveyed, along with rock and other foreign matter on a conveyor belt to the flotation tanks where a specialised process sorts the diamonds from the other material. A Siemens PLC is responsible for ensuring that this takes place efficiently.
Rudolph explains that since the Venetia mine and process control engineers were already entrenched in the Siemens control phil-osophy, it made perfect sense to replace the DOS-based Siemens S5 with a Windows-based Siemens S7. SAM was responsible for supplying the hardware and customised software infrastructure for the sorting line project, including the Siemens S7 PLCs, the cabinets, the CPUs and the scada system.
“In addition to tracking and monitoring of the sorting process, Venetia mine management expressed the need for redundancy in the system as well as accountability for the employees working on the process line in terms of changes made during production.”
He points out that the new system requires a user login before any changes can be made. “By implementing this simple procedural requirement, management can now ascertain who made changes in the system’s parameters and it also provides a date and time stamp on the action.”
Redundancy of the system was the other major requirement. “The client needed automatic activation of the redundant server in the event the primary server went offline. This ensures that the plant continues to operate without any interruption in the process,” adds Rudolph.
The contract to upgrade the sorting line was awarded in late 2013 and took only a month to implement. “We achieved this feat with minimal disruption to the process by replacing all the CPUs simultaneously on the fly over a one-hour shutdown period. We were then able to swap I/O over at our leisure. This was not a difficult task for us as we have gained extensive experience on similar upgrade swap-outs over the years. Our team leveraged their existing knowledge of process line installations to ensure there was minimal inconvenience to the client,” he continues.
“The sorting plant forms part of the larger, complex plant upgrade and modernisation programme that is being undertaken by a number of main contractors and project engineers, with SAM selected as the process control and automation subcontractor on each stage. This underlines the confidence all stakeholders have in SAM’s ability to design and implement the best solution for each individual aspect within the greater plant upgrade programme.
“A successful project can be attributed to a number of key elements including good communication between the stakeholders, teamwork and ensuring the necessary documentation between client and suppliers is in place. The SAM team of Duane Strampe, Manie Maritz, Armand Rudolph and Ryan Els worked synergistically and effectively with Siemens’ Tommie Chambers and EPC contractors Tenova Takraf’s team of Hector Matake, Theo Botha and Peter Drake to ensure the project met all time and budgetary constraints,” Rudolph concludes.
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