Optimization

Mine Merges Electrical, Process Controls

Vale's new iron ore mine is combining electrical and automation controls for big operational and productivity gains

By Jim Montague

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Cooperation is a wonderful thing because it adds and even multiplies the efforts of the players involved as they learn to pull in the same direction. However, some disciplines like electrical control and process automation had to historically remain separate because their applications, hardware and software were so dissimilar and applied in such different ways. Well, not anymore.

Leandro Monaco, ABB global product manager for System 800xA electrical integration, reported that electrical and process controls are coming together in some big applications, and achieving unprecedented joint performance gains and benefits—notably at Vale's huge iron ore mine in Belo Horizonte, Brazil. Monaco presented "Energy Efficiency in a Large-Scale Facility: The Electrical System Perspective" today at ABB Automation & Power World in Houston. The presentation was based on a whitepaper that Monaco recently co-authored with Jose Catarino, automation and electrical coordinator at Vale.

"The ideal management of a plant isn't just increasing production, but is also relating that production to energy consumption," said Monaco. "Production depends on the electrical system always being on, but one device failure can shut that production down. Power systems don't get much attention, most electrical maintenance is corrective, and this usually means hours of lost production."

ABB and Vale recently developed a remote asset management and predictive maintenance program for Belo Horizonte's electrical systems, which would also improve the mine's energy efficiency. "The mission statement of the remote electrical maintenance system is that it must deliver to the technician the same amount of information that he would see on the front of the cubicle in the field. This requires intelligent electrical device (IED) logic and parameterization; logical interlocks that operate within 10 milliseconds (so we can know which problem happened first); automatic uploading of disturbance record files, drawings and manuals; and sequence of events and alarm and events time-stamped by the IEDs. This allows users to change parameters remotely as needed, check and change breakers as needed, and address other problems early. This means electrical repairs that used to take nine hours or more will only need half an hour to fix and four hours to ramp back up to normal. That's 50% less time and lot of other savings, such as faster troubleshooting and less labor."

These savings are crucial because the mine represents a total investment of $19.49 billion, and when it begins production shortly, its 2,600 employees are expected to produce 90 million tons of iron ore per year. This will reportedly make it the second-biggest iron ore mine in the world behind Vale's other Brazil-based mine that produces 130 million tons per year. Belo Horizonte will use a truckless system, which will reduce diesel fuel costs by 71% compared to its sister mine. Electricity will be its highest raw material cost. Its electrical system will have 73 km of 230-kV transmission lines, 77 disconnectors and reclosers, and 135 medium-voltage (MV) substations with 1,500 to 2,000 IEDs. The mine's processing plant will have 30 substations, including one high-voltage (HV) and 29 MV substations, as well as 500 IEDs and 12,000 MV and low-voltage (LV) motors.

Monaco added that ABB's remote maintenance program at Vale will also mean far less checking of devices that don't need any maintenance. "One study showed that 63% of electrical maintenance hours resulted in no needed action, which is a big drain on labor," explained Monaco. "Bringing in open/close counts, trip counts, operating current values, spring charging times and trip circuit supervision data into an asset management can help head off problems without doing unneeded maintenance. Combining production data with energy consumption can also mean much greater energy efficiency, but we need to understand precisely and in real-time how energy is coming into the plant; measure how it's being distributed to each production area; do detailed measurements down to the LV and MV motors; and check the real-time ratio between plant production rates and energy used."

Bel Horizonte is using a fiber-optic network to connect all the meters and switchgear, as well as logic interlocks between relays. This has reduced cable requirements by 110 km, and enabled implementation of MV motors that comply with the IEC 61508 standard. "Vale has also saved about $4 million in man-hours in pulling cables and in installing, commissioning, testing and maintaining devices," added Monaco. "The mine also needed 83% less power meters in its substations, but has the same functions; gets the same information from its automation systems; and receives per equipment and plant reports. As a result, it also needs 75% fewer maintenance personnel."