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Cut costs and boost efficiency in mining

Fieldbus technology is making a huge difference to the way mines are operated and the industry is quickly embracing the change. Defined as an open, digital, two-way communication network, the term fieldbus encompasses a range of automated industrial network systems designed to communicate real-time distributed control of instruments and equipment.

Profibus has become the most successful fieldbus technology in factory and process automation, with over 35 million installed nodes worldwide since its inception 20 years ago. The water, wastewater and desalinated water industry has embraced Profibus enthusiastically across the country, as has the food and brewing industries.

Australia’s mining industry is now also increasingly introducing fieldbus technology to optimise asset management and maintenance routines as well as introducing process efficiencies linked to field level network communication.

Profibus DP technology has been the most widely used fieldbus in the mining industry and is now considered the standard for the intelligent control of drives widely used to operate the crushers, ball mills, SAG mills and other machines.

Another protocol within the Profibus family, Profibus PA, is designed to replace the classic 4 to 20 mA field measuring technology, by providing power and signal on a single twisted pair cable. In effect, Profibus PA functions as a two-way communication network that enables data to be sent to and from intelligent devices in the field to a control system.

This major breakthrough in fieldbus capability has successfully been introduced over the past ten years and more than 6 million PA network nodes confirm the viability of this technology.

In Australia, the Profibus International Competence Centre (PICC) is playing a leading role in promoting Profibus as the preferred choice for fieldbus communication.

The PICC was established by Tyco Flow Control over three years ago to provide certified training and technical support for end users. “Our task at the PICC, in collaboration with the Profibus Association of Australia, is to promote the emerging Australian success stories and provide training and technical assistance to end-users across the country,” explains Rafael Koenig, Controls Manager for Tyco Flow Control and Manager of the PICC (pictured above).

BHP Billiton Mitsubishi Alliance (BMA), Australia’s largest coal miner and exporter in Central Queensland, is a fine example of the benefits Profibus can bring to the mining sector. Traditional electrical installations within draglines have made it difficult for them to truly benefit from modern communication and automated systems.

The coal mining giant realised the need for a high-speed, robust communications protocol to communicate process-critical information between core controlling devices.

BMA Dragline uses Profibus.

BMA undertook a trial in 2002 to implement a Profibus network on a machine to assess the viability of this communication protocol in the harsh dragline-working environment. "Since this trial was the first such known installation in the world, we built in full hard-wired redundancy for the Profibus network," explains Andrew Guilbert, Manager Electrical Engineer, of consultancy firm Inete Pty Ltd.

The trial was a huge success and Profibus has now been adopted as a standard for communications between the controlling PLCs and the motion drives. "The redundancy has been stripped out of the machine effectively making the Profibus network the corner stone of the draglines operation." The robustness and speed of the Profibus network on this dragline has resulted in it being implemented on another seven lines.

Profibus also has the ability to quickly access and transfer intelligent data from multiple assets, significantly increasing the plant’s operational effectiveness. The development and introduction of the industrial Ethernet solution, Profinet, leverages web technologies and brings these benefits to the user. Profinet easily integrates Profibus as well as other networks and is an ideal way to evolve plants into an Ethernet based future without making equipment and skills redundant.

A surface coal mining operation in North Queensland’s Bowen Basin utilises a continuous mining and transportation system to remove and disperse excavated material of soil and rock. Three different Profibus networks operate within the Spreader operation.

Profibus boosts efficiency in mining.

The first operates the Sizer that crushes the excavated material. The second operates the ‘Tripper car’ as it moves laterally distributing the crushed material onto a mobile conveyor belt linked to the spreader while the third network operates the Spreader.

Many instruments are linked to these networks and regular feedback from mounted sensors is required for the system to work efficiently. Throughout this operation, the Spreader can ‘walk’ laterally up to 300 metres. The equipment was designed so that the Tripper moves with the Spreader while communicating over the Profibus protocol.

Profibus was chosen as the digital protocol to link the three networks within this operation because machinery of this size and complexity requires a fast speed of 1.5 megabits per second to communicate efficiently.

A few months after the Spreader began operations communication issues arose through poor quality signals, which eventual lead to frequent breakdowns in the dispersement operation.

Profibus was the backbone of the communication between the three networks and the operator. When the quality of the Profibus network deteriorated resulting in an unreliable flow of data, the three stages experienced frequent communication breakdowns.

PICC engineers visited the site to undertake a diagnostic assessment of the Profibus network and to troubleshoot and identify faults in the operation using recognised Profibus diagnostic tools – ProfiTrace and ProfiCore.

Initial findings revealed a number of concerns relating to signal reflections, faulty cables, interference and cable length issues. An investigation by the PICC experts revealed that the root cause of the network problems could be attributed to poor system design likely caused by the lack of Profibus specific expertise and training.

This reinforced the PICC recommendation of involving Certified Profibus Installers on such projects.

The mining industry as a whole is successively adopting Profibus as a powerful innovative technology and previous preferences of hardwired systems are becoming less attractive. “The miners are embracing useful change and put the old methods to one side so they can take advantage of the new technology,” emphasises Koenig.

“However, while we have on-site engineers and mining consultants who see the benefits of the technology, operations often cannot realise its full potential because they do not have the required Profibus skills or qualifications.”

To correct this, the Profibus Association of Australia offers a range of certified training courses.

“There is a need to demonstrate the diagnostic qualities, operational efficiencies and cost savings that the technology will bring,” explained Koenig.

“There is a need to demonstrate the diagnostic qualities, operational efficiencies and cost savings that the technology contributes,” explained Koenig. “We are quickly catching up with the rest of the world in terms of optimising operations and reducing the cost of ownership,” he said as more and more automation experts in the mining industry take advantage of a real opportunity to make long-term improvements to their operations.

Koenig is certain that Profibus technology is quickly becoming a standard on many mining sites, in the near future.

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