First Quantum Minerals Ltd. (FQM) is investing in a new trolley assist system for Hitachi dump trucks at the Kansanshi copper and gold mine, near Solwezi in Zambia. The massive project includes the installation of a new fleet of 23 electric EH3500ACII models as part of a four-year 370 million US$ expansion programme. Three different project phases are planned to increase annual copper production capacity from the 230 000 tonnes achieved in 2011 to 400 000 tonnes by 2015. The trolley assist package commenced in March 2012 with the installation of a 750 m-test track and overhead line for trials by Hitachi engineers.
Kansanshi is Africa‘s largest copper mine – and the eighth largest in the world – with an estimated lifespan of at least 11 years. 80 % of the mine is owned by Kansanshi Mining PLC (a FQM subsidiary) and the remaining 20 % belongs to a subsidiary of ZCCM Investments Holdings, 85 % of which is owned by the Zambian Government. Mining is carried out in two open pits, which are known as Main and Northwest. FQM uses conventional open-pit mining methods and employs hydraulic excavators and a fleet of rigid dump trucks. The line-up of large Hitachi excavators includes: 2 EX1200- 5s (with over 38 000 and 42 000 working hours respectively); 4 EX1900-5s (27 000 to 40 000); 1 EX1900-6 (over 14 000); and 3 EX2500-6s (7000 to 20 000). However, the existing fleet of 11 EH3500ACII trucks is the most recent addition to the Hitachi stable at Kansanshi, with 2000 to 6000 working hours between them.
John Coleshaw, FQM‘s Project Manager, says, „The EX1200s, EX1900s and EX2500s are quite old now, with some having accumulated more than 40 000 hours. They have given good service and we can‘t fault them. A main benefit of these models is the automatic retarding control to regulate the downhill speed, which is excellent for safety and preserves the lifetime of the product.“
The new EH3500ACIIs have started to arrive on the site and will be ready for full operation with the new trolley line by March 2013. The design of these electric dump trucks has become a more simplified process since the turn of the century. Technological innovation has opened the door for the powerful AC drive to replace the traditional DC drive.