Ball mill upgrade at Collahuasi increases processing capacity by 4.4%
The upgrade was achieved without safety incidents in 71 days, 13 days ahead of the initial schedule. It involved changing the rotor, GMD system stator and redesigning the mill discharge to achieve an increase in both available power and the level of filling required to treat a harder ore.
Collahuasi is one of the most important mining companies in the world. In 2018 it produced 559 thousand tons of fine copper, equivalent to 9.5% of Chilean copper production. Its shareholders are Anglo American plc (44%), Glencore (44%) and Japan Collahuasi Resources B.V. (12%).
During 2019, Collahuasi proposed that Metso lead the difficult and important work of upgrading its mills, a task that prior to 2019, had been handled by other contracting companies. Metso, working with Collahuasi, managed in 71 days to successfully complete the project, without accidents and to carry out the final commissioning without setbacks.
The mill upgrade was carried out in 13 days less than originally projected, which meant a 21% saving in time, positively impacting the availability of the equipment and establishing a record at runtime.
Within the mining company's overall strategy, increasing its production was an important element. Given this, expanding the capacity of its line 3 in the plant was a key factor. It is crucial to point out that this line is responsible for 60% of Collahuasi's production and was for many years the largest line in the world and is still currently one of the most important worldwide.
Ball mill 1012 is located in line 3 of the mines production circuit and had the potential and capacity to process more material if some modifications were made. Collahuasi decided to award the project of repowering this mill to Metso, given the previous positive experience and years the two companies had worked together.
For Dalibor Dragicevic, Executive Vice President of Operations of Collahuasi, the project was an experience that allowed them to realize the potential of their mining work teams. "We decided to assume a leading role governed by our management model, which is the Risk Management Cycle. From that, we now have the confidence and conviction as a team that we can lead challenging, complex and demanding projects such as this one while controlling risks,” says Dragicevic.
How were the days decreased?
Upgrading a mill is a complex job which requires a joint effort between both the engineering and services areas. There are two keys that help guide a successful project, comprehensive and realistic planning, as well as having a close and efficient working relationship with the client. However, both of these depend on having suitable people with the right skill set for proper execution.
In the case of the ball mill 1012 upgrade, the original planning included 90 days to execute the project. The proposal was analyzed thoroughly, and the revised plan called for the completion in 82 days of work. This involved, among other tasks: changing the rotor, stator and cooling boxes of the GMD system, as well as redesigning the discharge of the mill. These changes would achieve an increase in available power and also increase the level of filling required to treat harder ores, in turn realizing an increase of 4.4% in terms of processing capacity. All these tasks were completed within the tight schedule.
Considering the complexity of the project, close collaboration was key to achieving success.
“The service planning took about 5 months. In this process, it was key to have partially participated in the previous upgrading of Ball Mill 1013, because we were able to learn and implement continuous improvement to our entire proposal. Therefore, we managed to be thorough and realistic, “says Cristian Fadic, Vice President of Mining Services South Cone in Metso.
Among the technological tools used to improve the performance in the field was a video that was prepared, involving a 3D survey of all work that needed to be done. In this way, workers could preview each part of the process and the general drawings of the project.
One of the critical factors in carrying out the initiative in the required time frame was the relationship between Metso and Collahuasi, coupled with the mine’s active participation.
“It is not usual for the client to be accompanying you for 24 hours on a project. This is what Collahuasi did. This allowed for quick and efficient decisions, which greatly facilitated the project’s execution. If something was missing, they actively collaborated in finding the right solution. On our side, if something extra was needed such as our participation in civil works, then we helped without any delays. Considering the complexity of the project, close collaboration was key to achieving success.” says Fadic.
Finally, the mill upgrade was carried out in 13 days less than originally projected, which meant a 21% saving in time, positively impacting the availability of the equipment and establishing a record at runtime. In addition, it was carried out without accidents, an issue that is essential for the values of Collahuasi and Metso and is therefore included in the Project Risk Management Cycle.