Maximizing ROI at Grupo México’s Buenavista ESDE III plant

Operated by Grupo México, one of the world’s major copper producers, the ESDE III SX-EW plant in Buenavista, Mexico is the world’s largest SX plant. Having previously manufactured similar SX-EW equipment for other Grupo Mexico projects in the region, Outotec was the natural choice to supply the technology. Furthermore, Outotec’s solutions had proven to be capable of coping with the challenging process conditions at Buenavista during the testing phase. Seamless cooperation between the project partners ensured fast implementation and start-up, with the plant coming online in June 2014, just over two years after the contract was signed.

Maximizing ROI at Grupo México’s Buenavista ES DE III plant

Grupo México is one of the most important companies in Mexico, Peru, and the US, and is one of the world’s major copper producers. Founded over 70 years ago, the company has been listed on the Mexican Stock Exchange since 1978 and is one of the most traded stocks on the exchange. The companies that comprise Grupo México have shown particular interest in preserving the environment and the social and economic development of neighboring communities. The group currently operates 13 mines and has 13 ongoing exploration projects.

The group’s Buenavista plant is located close to the town of Cananea in northern Mexico. Prior to the ESDE III project, the Buenavista plant had two SX-EW plants, ESDE I and ESDE II, with a total annual copper cathode production capacity of 55,000 tons. In early 2012 the company decided to expand the plant’s capacity to produce copper cathodes via a leaching-SX-EW process. In April 2012 Grupo México signed a contract with Outotec for delivery of a copper SX-EW technology package for the ESDE III plant, with an annual copper cathode production capacity of 120,000 tons.

Reaping the rewards of a long-term relationship

Cooperation between Outotec and Grupo México in the area of hydrometallurgy had begun several years previously when Outotec (then Outokumpu Technology) performed a VSF (vertical smooth flow) pilot test run at the Buenavista site. Several joint testing and development initiatives were subsequently carried out, including a test run of a full-scale SPIROK mixer at the ESDE II plant. “Due to the metal content of the PLS, it was important to select technology that would allow us to minimize the mechanical and chemical entrainment of the PLS in the organic phase, in order to keep control of the electrolyte quality,” says Ramon Bustamante, ESDE III project manager, Grupo México. “With Outotec’s VSF SX technology, Buenavista has achieved good control over entrainment at the ESDE III plant, leading to good copper cathode chemical characteristics and appearance.”

After deciding to go ahead with the ESDE III project, Grupo México evaluated several alternative suppliers. One of the primary reasons behind selecting Outotec was that the company had a proven track record in manufacturing SX-EW equipment for other Grupo Mexico projects in the region. It had also been demonstrated in the earlier testing phases that Outotec’s technology was highly suited to the challenging process conditions at the Buenavista plant.

World-class expertise and technology ensure success

The equipment manufactured for the group’s postponed Tia Maria project in Peru was stored in warehouses around the world and was readily available to be transported to Buenavista. In addition, a large part of the engineering work performed by Outotec for the Tia Maria project was applicable to ESDE III; the existing equipment only required minor modifications to adapt it for the different process and climate at Buenavista. This meantcthat the ESDE III project could be implemented in a very short timescale – the contract was signed in April 2012 and the first copper was produced in June 2014, with the copper quality immediately achieving LME A grade. Seamless cooperation during the project between Grupo México, their engineering and construction contractor, and Outotec was an essential factor in this achievement.

“The Outotec team was involved in the project from the basic engineering phase at the Santiago office,” explains Bustamante. “Because the PLS copper content at Buenavista is much lower than at the Tia Maria site, the SX-EW plant was redesigned to include one additional SX train to feed the required amount of copper to the EW tankhouse. After that, the team was also involved in the detail engineering in Mexico City, and finally in construction and start-up of the entire plant,” he continues. “Outotec’s contribution in the detail engineeringphase was very valuable, especially for the piping discipline, which was one of the most time-consuming parts of this phase.”

The Outotec team was on site during construction and start-up to provide technical assistance. Their presence was key during the installation of the fiber reinforced plastic settlers, helping to ensure that no leaks were detected during hydraulic testing and that the installation of all the Outotec DOP® and SPIROK® mixer systems were properly aligned in order to optimize the flow rates. This meant that commissioning and start-up activities could be initiated earlier than scheduled, and that cathode production could begin earlier than expected. “The technical assistance of the Outotec team with all the proprietary equipment installation and start-up was highly valuable in all areas of the plant,” Bustamante concludes.

Cooperating to ensure a sustainable future for Buenavista

Looking to the future, Outotec and Grupo México are actively cooperating in fine-tuning operations at the ESDE III plant and developing the optimum setup for Outotec’s aftersales support. One concrete example of this is the maintenance and aftersales service center that Outotec has established in the city of Hermosillo, close to the Buenavista site. This center will form the base for the support activities required by the plant. The common goal is to maximize the profitability of the ESDE III investment for Grupo México without compromising the commitment to sustainability.

*This case study has been written prior to the merger of Metso and Outotec.