CLC has had several successful programs with Metso in order to reduce ball consumption and grinding ball inventory, save energy or improve the end product from the grinding stage. Since the start of operations, one real change was implemented and another might be just around the corner. A couple of years ago, tests were done with feeding different ball sizes (80 mm and 60 mm) into the mill, but it didn’t lead to significant improvements. A decision was then made to continue producing with only the 80-mm size balls. A later test was carried out with harder grinding balls, and a significant increase in life-time was detected. The balls have a higher wear-resistance and keep their round shape a lot longer. Today CLC and Metso are planning a new pilot test with superior quality balls to determine whether the yearly ball consumption could be further reduced.
Mr. Alcón clearly states that all of these challenges are positively impacted by many factors, among which, for sure, is the quality of Metso’s grinding balls. “Since the start of the operations here, we haven’t seen any broken balls and the shape of the balls produced by Metso are close to being perfect,” he says. “These clearly influence the grinding efficiency and energy consumption in a positive way. Over the years, Metso has always partnered with us to find better solutions to these challenges. They bring us the best benefits when comparing grinding media and mill linings from other suppliers. Today our whole plant is running at over 95% availability, which is above international standards, and we’re sure that is partly the result of working together with Metso.”
After energy consumption, grinding media has always been the highest operating expense for many mining customers. Reducing grinding consumption while simultaneously improving grinding efficiency and reducing energy consumption are common issues in the mining industry. “Our grinding balls can help improve each of these in a significant way,” says Mr. Santiago Fernandez, Manager of Metso’s Forjas del Guadalquivir operations and manufacturing. “This, in combination with our proximity to Cobre Las Cruces, has benefited our valued customer. Thanks to lower inventory levels, lower ball consumption and more recovery, they are able to better use their financial resources.”
Longer wear life and fewer liner changes reduce costs by around 15%
In addition to the grinding media, CLC is also using Metso’s Poly-Met™ mill lining, which they are very satisfied with, according to Mr. Rafael Sánchez, Maintenance Supervisor at the CLC plant. “We are able to change the plates and lifter bars inside the whole mill in only 2 days; and since we are using the Poly-Met lining, we only need to do this every 7 to 8 months. This previously was needed every 4 to 5 months. This reduces our plant downtime and, consequently, also the costs involved. Since we changed to the Poly-Met mill lining, our costs decreased by around 15% due to the longer wear life and fewer liner changes. The Metso grinding balls also have a positive influence on the changing schedule, as the quality of the balls definitely increases the lifetime of the linings,” he stipulates. “Together with the Metso crew we’re now looking into increasing the lifetime of the mill linings even further by eventually switching to a thicker size. Many factors influence the time between changes (quality of the grinding media and mill lining, mill speed, mill lining design, etc) but we have no doubt that we’ll find the right balance with Metso’s help,” he concludes.
“Cobre Las Cruces is very happy with Metso’s support and collaboration. Having been able to reduce the consumption of grinding media by 10% has easily translated into savings of several hundreds of thousands of euros. Needing to handle fewer balls over time also has an effect on the health and safety of our people. Fewer ball changes needed and no broken ones inside the mill reduces the risk of accidents – and that is also worth mentioning!” Mr. José Luis Bonilla, responsible for external relations at Cobre Las Cruces, states. “The constant monitoring of operations and looking for improvements is an ongoing project. The material to be processed and the conditions often change, so there is no absolute solution for these topics. Close communication with our partners and a good understanding of our operations is therefore key – and Metso is definitely one of those partners!” Mr. José Luis Bonilla says.
“CLC cares a lot about the environment and is committed to it. We are working on continuously restoring the natural surroundings of the mine. All extracted material that cannot be sold is redistributed on the area around the mine. It is part of our management system and our company culture,” he concludes.
*After this article was written, Metso has divest its grinding media business to Moly-Cop
*Metso Outotec was formed July 1, 2020 when Metso and Outotec merged into one company. This case study has been written prior to the merger under the old company name.