The Palabora copper mine in South Africa is one of the largest copper mines in the world. Studies have shown that additional ore-bearing layers are present below the base of the open cast mining. The Palabora Mining Company thus decided to extend the copper mining underground. Subsurface block mining with a daily production of 30,000 tons is an economically acceptable way of maximizing the recovery from the deposit. This would guarantee operation of the Palabora copper mine for at least another 20 years. When mining the subsurface deposits, it is planned to increase the efficiency of mining operations even further by using modern automation equipment and tele-controlled machines. A key factor of the equipment is the communication network, which must ensure reliable data transport both in underground areas subject to explosion hazards and in the open cast mining.
The Palabora Mining Company decided to install an information and data network (Integrated Information Network, IIN) throughout the mine. This communication network can be subdivided into two sectors: Real-time control and monitoring of production and Automation of machines and plant The objective is to lengthen the daily operative times, increased productivity, integrate data acquisition and diagnostic features and increase the degree of automation. On the one hand, the system is designed to provide comprehensive information on operations throughout the whole mine for the management. At the same time, the operating personnel at the control panels need direct control and monitoring of underground mining activities.
Open communication standards are used at all levels to control the machines and plant. Industrial Ethernet was used at the control level, PROFIBUS-DP and PA at the field level and AS-Interface at the sensor/actuator level. At the control level, each of the PLC controllers (Siemens S7-400) and PC's communicate with each other and with the master controller through Industrial Ethernet. The open cast mining, which is not subject to explosion hazards, uses PROFIBUS-DP for the field devices. It connects the remote I/Os, drives, operator panels, motor protection units and control units to the PLC's. Segment connectors from Pepperl and Fuchs and DP/PA links from Siemens are used to interface the explosion-protected PROFIBUS-PA network for the underground field devices to the DP network. Current transformers for pressure and differential pressure, temperature and flow (Endress and Hauser) and control valves (Samson) are connected to PROFIBUS-PA.
The use of modern open communication technologies has resulted in major cost savings in installation, hardware and engineering. In addition, benefits are obtained from the functional advantages of digital communications. For example, all diagnostics data can now be transferred directly from the field devices to the control room. This increases reliability and significantly reduces plant downtime. The extensive diagnostic functions allow preventative maintenance and coordinated service work. A particular advantage is that operation and configuration of field devices from various manufacturers in the PROFIBUS-PA network can be carried out over the network with a single engineering tool (Commuwin from Endress and Hauser).
Following a comprehensive analysis of all commercially available industrial communication systems, the Palabora Mining Company chose PROFIBUS to be the most suitable fieldbus system for their H2 area (open cast) and H1 area (subsurface). All of the technical requirements on the network were met without limitation.
Some of the companies who participated in the automation of the plant were Endress & Hauser, Pepperl & Fuchs, Samson and Siemens.