The world's most powerful GMD

Handling immense process capacity and challenging ore characteristics under extreme environmental conditions.

Processing ore at highest altitude - and in an area subject to frequent seismic activity - places huge demands on the electrical and process equipment. It calls for a partner who can provide exceptionally robust and reliable grinding technology. Mine operator Minera Chinalco Peru selected ABB to become part of this pioneering attempt to raise the bar in high-altitude commercial mining. 

Toromocho copper mine
Toromocho Mountain is one of the world’s largest untapped sources of high-quality copper. It is also one of the highest, located at an altitude of 4,700 meters above sea level in the mining district of Morococha in the Junín Region. The mine is projected to deliver 1 million tons of copper concentrate, 10,000 tons of molybdenum and 4 million ounces of silver oxide annually over a period of 32 years. 


  • Extreme altitude and remote location
  • Seismic activity
  • Managing high processing capacity

Our solution 
Early project involvement with Jacobs Engineering and Minera Chinalco was key in developing the best fit of drive solutions for the site's challenging requirements. As a result, ABB developed three of the largest diameter and most powerful drive systems for a SAG and two ball mills installed at the highest altitude to date. The fully integrated and optimized solution for the grinding circuit consists of: 

  •  1 x 28 MW  GMD to power the 40 ft SAG mill
  •  2 x 22 MW GMDs to power two 28 ft ball mills 

The site's altitude and high power system required ingenuity and flexibility when in came to engineering the three systems. Some of the changes compared to GMDs for lower altitudes were:  

  • New cooling system able to dissipate heat generated by the most powerful GMD at this altitude
  • Optimized motor insulating material tested and certified for operation in such demanding conditions
  • Cycloconverters with 18-pulse configuration instead of the regular 6-12 pulse cycloconverter

The design innovations also had an impact on logistics. Motor and cooling system in particular had to be designed in such a way that they could be transported on winding mountain roads and through numerous tunnels. The motors were shipped in four segments, each one 15 meters in length and weighing up to 130 tons. The huge cooling system also had to be transported in segments, small enough to pass through the restricted height clearance of the tunnels.

Other ABB design innovations for Toromocho include an airlock system to protect the three GMD E-houses from dust and maintain the correct air pressure inside. And each GMD is fitted with a large number of sensors and instruments in order to monitor the machines during operation. This provides the motors with better protection and, when combined with ABB’s remote diagnostics service, is a powerful tool for preventive and predictive maintenance. 

The full scope of ABB delivery includes design, engineering, installation supervision and commissioning of all three drive systems. All electrical products and GMD components manufactured by ABB for use at Toromocho are certified for use at the higher altitude of 5,000 meters above sea level. 

  • Variable ore qualities throughout the ore deposit (including very hard rock) 
  • Managing high process capacity 
  • Remote location 
  • Extreme environmental conditions (challenging access road, varying temperature

Main data


Minera Chinalco Peru


Toromocho, Peru

Customer need: 

Highly reliable mill drive systems to power mega mills that can handle immense process capacity and challenging ore characteristics under extreme environmental conditions


  • 1 x 28 MW GMD system
  • 2 x 22 MW GMD systems
  • Design & engineering
  • Installation supervision
  • Commissioning


1 x SAG mill 
2 x Ball mills

Customer benefits:
  • Integrated, robust and fit for purpose mill drive system 
  • Maximum throughput and grinding availability 
Commissioning year: 2014

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