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The two milling trains of Kalumbila Minerals process 55 megatons of ore per year and achieve a top ranking in terms of performance and efficiency


Mining for productivity and profit

Kalumbila Minerals Ltd., a subsidiary of First Quantum Minerals Ltd., had ambitious output goals for Sentinel, its copper mine development project in northwest Zambia, and needed to recruit an entire workforce to build the infrastructure from scratch, all while minimizing costs. Siemens was happy to assist.

Harsh environments, rising energy costs, and water scarcity are just a few of the challenges facing the world’s mines. Kalumbila Minerals was not only confronted by these challenges but also had more to grapple with when building two mines in an isolated area 150 kilometers west of Solwezi, Zambia.

The region had practically no infrastructure for transportation or energy supply, and no workforce with the skills to build one. The local population worked in farming and ranching and had no experience with large construction projects. But having committed to source at least half of its workers locally, Kalumbila Minerals needed to find and train at least 4,000 people to lay roads, weld pipes, erect pylons, and even construct a new airstrip. A further challenge was Kalumbila Minerals’ ambitious production targets: 300,000 tons of copper and 38,000 tons of nickel concentrate per year within the first six years of operation. Meeting this output target would demand advanced drive technology that could power all the mining machinery around the clock with minimal downtime.

To overcome the challenges and make the project a success, Kalumbila Minerals recognized the need for a partner that could offer a comprehensive solution for both training new workers and providing high-performance integrated drives. End-to-end process optimization was the only way the company could hope to overcome its production challenges while minimizing operational and extraction costs.

“For projects involving limited local skills and complex equipment, what we look for in a technology provider is a robust product and a skilled team with the ability to transfer knowledge to our local expert teams,” says Nevin Scagliotta, commissioning manager for First Quantum Minerals Projects Division. “With mills of this size, reliable and high-efficiency drives are top priority and crucial to project economics.”

Driving recruitment and power

As a technological leader in the global mining industry, Siemens was the obvious choice to provide the advanced drive technology that would give Kalumbila Minerals the power and the cost optimization it needed. With its experience in implementing and managing large-scale mining projects all over the world, Siemens also knew what steps to take to successfully source and train the new workforce.

To fulfill its commitment of hiring 50% local staff, Kalumbila Minerals recruited 4,000 workers from the surrounding towns and hired 4,000 indirectly through on-site contractors. Siemens’ project team, comprising professional engineers, seasoned assembly supervisors, and on-site start-up engineers, then transferred its expert knowledge to the local teams so the mine could be running productively in the shortest possible time.

Rugged power and close control

With projects of this size, it is advantageous to reduce the number of supplier interfaces, and thus to have the entire drivetrain supplied by a single source. Integrated Drive Systems from Siemens offer the only true one-stop solution for drive systems worldwide.

To power the extraction of 300,000 tons of copper and 38,000 tons of nickel concentrate per year, Siemens provided the motor and drive systems for two 40-foot semi-autogenous grinding (SAG) mills powered by 28-MW gearless mill drives (GMDs) and two 28-foot ball mills powered by 22-MW GMDs.

Among the world’s biggest and most powerful drives, the integrated GMDs from Siemens provide Kalumbila Minerals with the end-to-end ­process optimization essential to maximize efficiency and minimize cost. The drives also provide outstanding reliability due to the ad­vantages of the gearless design. With no moving gears, there is no variance in the motor and no vibration. This vastly reduces energy loss, as all the force is transferred touch free via the magnetic field. The lack of moving parts also virtually eliminates wear and tear and the risk of downtime. In the event that maintenance is required, the drives maintain high availability thanks to their dedicated maintenance modes, such as creeping or inching with rollback of the mill.

Axel Fuchs, Project Manager at Siemens Process Industries and Drives

Torque and speed control, and especially the frozen charge protection keep the mill operating in the safe range, minimize downtime, and keep production high.
Axel Fuchs, Project Manager at Siemens Process Industries and Drives

“Torque and speed control, and especially the frozen charge protection keep the mill operating in the safe range, minimize downtime, and keep production high,” says Axel Fuchs, project manager at Siemens Process Industries and Drives. “The Siemens GMD offers 28 MW and a 150% overload – no other drive is able to do that at 9.1 rpm.”

The integrated drive train came along with Simatic PCS 7 and Sinamics SL150 cycloconverter technology. The Simatic PCS 7 controller for the mill drive and Kalumbila Minerals’ existing distributed control system could be seamlessly integrated thanks to their common platform, while the rugged Sinamics SL150 offers exceptional overload capacity and high efficiency through direct energy transformation, which results in availability of more than 99.5%.

A proven mining partner

Siemens proved itself to be a trusted partner with the provision of a quality service. This included the professionalism with which its team managed the project and the engineering expertise demonstrated by its gearless drive technology. Ultimately, Siemens’ know-how and experience were successful in helping Kalumbila Minerals increase the productivity of its mines while reducing costs, demonstrating why Siemens continues to be regarded as the partner of choice for the world’s global mines.

“For a critical and complex piece of equipment like the mill drives, it is vital to have a self-managing and professional vendor. This is what Siemens has provided with its gearless mill drives and the commissioning team,” says Nevin Scagliotta of First Quantum Minerals.

Benefits of Siemens’ gearless drive technology

  • Reliability – rugged design that assures 99.5% availability
  • Low cost – optimized electrical efficiency and no wear and tear
  • Integrated solution – end-to-end technology and services that keep the mills running
  • Minimized downtime – dedicated maintenance modes that keep performance high
  • High productivity – efficiency of 95% thanks to the gearless design
Helmut Liepold
Picture credits: Siemens AG