ABB has supplied an array of power and automation solutions for Antofagasta's new flagship Esperanza copper mine in Chile. The solutions include three of the world's largest gearless mill drives, process and electrical control systems, power quality systems, a substation and a System 800xA integrated operations center that controls the entire production process, including onshore facilities at a purpose-built port 145 km from the mine.
Officially opened in April 2011, Esperanza is the first large-scale mine to use raw seawater in its metal-producing processes. The water is pumped from the coast through a 145-km pipeline to the mine, 2300 meters above sea level. Esperanza has a daily throughput capacity of 97,000 tons of ore. After extraction in the open-pit mine, the ore is crushed in a huge 40-foot semi-autogenous grinding (SAG) mill and two 27-ft ball mills, all three of which are driven and controlled by ABB gearless mill drive systems with a massive power output of 22.4 and 18.6 mw, respectively.
When the contract for the mine's gearless mill drive systems was awarded to ABB in 2007, Esperanza was only the second mine in the world to install a SAG mill, and the first to install ball mills with these capacities and power ratings. These records have subsequently been superseded by ABB at other mines, but at the time they were at the technological limit of what SAG and ball mills were mechanically capable of achieving.
The gearless, mill-drive systems enable the grinding mills to achieve the best possible grinding results and process efficiency by adjusting the speed or direction of the mega-sized mills, and ensuring a constant particle size, regardless of changes in the size or hardness of the ore.
Figure 2. Three huge mills grind ore into particles at Antofagasta's Esperanza
copper mine in Chile. Each ABB gearless mill drive system comprises a large,
gearless synchronous motor wrapped around the mill like a ring. The power and
control equipment is located in a purpose-built E-house container with
built-in cycloconverter, motor control center and programmable logic
controller (PLC), converter transformers and excitation transformer.
Photo courtesy of Antofagasta.
The ore is transported to and from the grinding mills by heavy-duty conveyor belts. The belt motors are driven by ABB medium-voltage variable-speed drives, which provide dynamic control of the motors, and enable soft starting and stopping of the belts, thereby saving energy and minimizing mechanical wear and tear. After processing, the concentrate is transported through the pipeline to the port where it is thickened and stockpiled, ready for loading onto ships. An ABB 110/23 kV substation connects the site and its onshore and offshore facilities to the power grid.
Esperanza consumes huge amounts of electric power, and requires power quality equipment to maintain voltage stability and a high power factor. The site's power distribution network is controlled by an ABB supervisory control and data acquisition (SCADA) system, and is protected from destabilizing voltage spikes and harmonics-induced power losses by an ABB filter system.
The ABB System 800xA distributed control system integrates all the automation systems—process, power distribution, gearless mill drive, motor and conveyor, pipeline and port—into a common control environment, and provides interfaces with the plant management and maintenance systems.
Full visualization and control of the whole process (crusher area, processing plant, pipelines and port) is provided by ABB's Extended Operator Workplace (EOW-x) integrated operations center, which is a unified and ergonomic control room environment that is designed to maximize operator efficiency.