Progress on integrated mining solutions provider Fermel’s 25 t direct electric drive haulier prototype is 85% complete and scheduled to be deployed with locally developed high-speed charging infrastructure at a major South African platinum producer in the first quarter of next year.

Johannesburg-based Thuthukani Consulting Engineers designed a number of electrical systems used on the haulier. These include auxiliary battery storage; electrical propulsion, comprising traction control and torque vectoring systems; cooling; electrical management; and electrical distribution systems.

Thuthukani electronic system engineer Calvin Coetzee asserts that the most significant advantage of the haulier is the limited energy lost through the drive system, offering up to 80% tractive efficiency. Further, the haulier can recharge the battery back during braking and decline travel

, while the traction system can provide up to 400 kW of power, which is liquid cooled to improve equipment uptime.

He highlights that the control system of the haulier is completely drive-by-wire, or computer operated, with a six-wheel torque vectoring and traction control system for incline and decline hauling.

The haulier also uses counter- and crab-steering for improved manoeuvrability and hydraulically actuated suspension for increased control during the loading or discharging of rock.

Coetzee notes that the high-voltage lithium-ion battery pack in the haulier is removable and can be charged in about one hour and 45 minutes using current charging technology. The battery pack is also fault tolerant and is monitored by a unique battery management system.

Further, the design of the haulier’s electrical system can maintain safe voltage levels, enabling personnel to safely perform maintenance.

Coetzee tells Mining Weekly that, if the prototype testing is successful, commercial manufacturing of the haulier could start in the second half of next year.

According to Coetzee, the design and development of the haulier’s electrical system lead to the discovery of numerous opportunities to improve mining operations and achieve significant cost savings.

He adds that, if current battery technology was measured on a life-cycle cost basis, it would be a more cost-effective solution. “Battery systems enable mine operators to significantly improve their energy mix using installed systems for grid storage to be used only during peak times. We approximate that, if capital and operating costs are taken into account, mining operators could save up to 40 % in underground mine development and up to 44 % in operating costs.”

Coetzee explains that, because battery-powered mining machines emit less heat during operation, 30% to 50% less ventilation is required, compared with conventional diesel-fuelled mining machines. “Infrastructurewise, these machines would allow for development costs to be cut, owing to the lower ventilation requirements.”

Removing the diesel component also means that there are no toxic emissions during normal operations.

Battery systems can be applied to mobile conveyors, emergency pump systems, standby power, temporary processing plants and, theoretically, even low-noise rock drills. “No diesel handling would be required and the technology is adaptable to trackless and rail-bound equipment. Electrically driven machines even have lower operating noise.”

There is extensive scope for Thuthukani and Fermel to embark on more joint ventures in the future, says Fermel mechanised solutions business development manager Bobby Conradie. “This partnership is aimed at creating a single point of entry to zero-emission mining solutions by combining the expertise of Thuthukani and Fermel. “It provides the ideal platform for end-users to gain access to tailor-made electric solutions for specific mining conditions using the latest battery, electric drive and vehicle control technology.”