DAYE Copper Smelter achieves improved operational efficiency with Metso Outotec’s High Oxygen Enrichment Lance Upgrade

Located in Huangshi, China lies the world’s largest TSL smelter operated by Daye Non-Ferrous Metals Co., China’s oldest copper producer. The smelter has been operating for almost 10 years and has a design throughput of more than 1.5Mtpa of copper concentrates. The site is currently facing challenges to reduce their environment footprint whilst simultaneously increasing production and operational efficiency.

Environmental sustainability is at the forefront of industry conversation, and metals processing is no exception. With the continued push to improve energy efficiency, increase throughput and reduce CO₂ emissions, increased use of oxygen in non-ferrous smelting presents a compelling pathway to achieving these goals.

Through close collaboration during the engineering design and commissioning phases of the project, Metso Outotec was able to assist DAYE in improving performance of their Ausmelt TSL copper smelter by increasing oxygen enrichment of the process air up to 75%. Due to an innovative lance modification, this upgrade resulted in a variety of short-term and long-term benefits, including financial, operational, as well as environmental.

Identifying the need for change

When operating a smelting plant, there are several challenges each plant will inevitably face. First, there is the desire to improve energy efficiency and reduce the consumption of fossil fuels such as coal, oil and natural gas. Not only do these constitute an operating cost to the smelter, but there is also the added—and quite significant—environmental benefit of decreasing the process carbon input through a reduction in fossil fuel consumption.

challenge is a throughput related obstacle. By improving the process energy efficiency and reducing consumption of coal, this results in a larger capacity to increase raw material processing and consequently copper output.

In regard to the Ausmelt TSL process specifically, increasing the lance air oxygen enrichment presents a challenge to ensure lance tip integrity and thus operational availability are maintained. This is due to both a reduction in lance cooling intensity with lower injected flows, as well as more intense reactions at the lance tip between the fuel and oxygen enriched air, which have the potential to negatively impact lance life.

The Daye Copper Smelter facility was aware of the possibilities to address these challenges, as other sites have implemented similar improvements to much success. Their goal was to improve environmental performance and reduce their operating costs whilst opening up the possibility to increase smelter productivity.

Minimizing environmental impact & maximizing operational efficiency

Commissioning of the equipment upgrades and improved copper smelting process began in March 2019, with James Coveney - Senior Process Engineer & Ross Andrews - Process Design Manager, traveling to China to visit the site.

“The aim of this project was to upgrade the lance so the process could operate with a higher oxygen enrichment,” says James. “This would result in increased throughput and less fuel consumption, which would also lower the CO₂ footprint. These are the main drivers of every operation right now.”

Through modifications to the existing Ausmelt Lance and Process Control System (PCS), oxygen enrichment of the lance air was progressively increased from around 60% up to 75%. Implementation of high-enrichment operation did not necessitate any changes to the lance trolley or catenary hoses, whilst only minor changes to the lance valve train were required to ensure instrumentation was ranged appropriately for the new air and oxygen flows.

“Lance flows dictate not only fuel combustion and oxidation of the feed, but they also work in promoting cooling of the lance,” James states. “Modification to the existing lance design was necessary in order to ensure this was maintained.”

Six months later, the commissioning team returned to the site and reviewed the performance of the high oxygen enrichment upgrade. Much to their satisfaction, the feedback was overwhelmingly positive. It was abundantly clear that there had been measurable improvements within the site’s operations, specifically a reduction in coal consumption.

Reductions in fuel coal consumption realised at DAYE as a result of increasing the lance oxygen enrichment aligned well with what was expected. Figure 1 presents the reduction in coal fuel consumption at DAYE, via implementation of high enrichment operation.

Despite a reduction in the total gas volume injected via the lance, increasing the oxygen enrichment did not negatively impact lance life, with the duration between repairs to the lance tip maintained between 7 and 10 days.

Implementation of high enrichment operation has also created a multitude of additional benefits for the customer. Less fuel coal consumption has resulted in both operational cost savings as well as a reduction in both CO₂ and NO_x emissions to the environment. A reduction in the total gas volume injected via the lance has also provided noticeable improvements to both the life of the furnace refractory lining and smelter building hygiene. The upgrade also gives the customer scope for increasing throughput.

Utilising local resources to achieve global success

From collaborative design to physical implementation, the local market area personnel played a key role in helping this project come to fruition. With support from the local team, all technical information and services were able to be provided in the language of the customer. Their significant contribution to this project helped to improve communications and foster long-term relationships. The success of this implementation has allowed for ongoing projects with the site.

“This was an important and extensive project, since this was not just a bolt on improvement,” says Jacob Wood - Customer Account Manager at Metso Outotec. “There was an acknowledgement on the customer side that we had the technical knowledge to implement the upgrade and achieve this positive outcome. They trusted our solution would result in more than they could purchase from our competitors.”

High oxygen enrichment for oxidative processes, such as copper and nickel smelting, provides an effective pathway for improving operations at existing Ausmelt TSL smelters. High enrichment in reducing processes such as tin smelting and zinc residue processing may also be attainable through a more complex solution encompassing a water-cooled lance. With  this experience, Metso Outotec can provide tailored upgrades to any interested TSL customers.

It is Metso Outotec’s core expertise to support customers in transforming the industry. With this upgrade, DAYE’s operation was able to improve their performance whilst significantly lowering their environmental footprint. That’s why, together, Metso Outotec is the partner for positive change.

This article is part of our Smelting Newsletter Issue 1/2021. Visit the issue front page for all articles and greetings from Jyrki Makkonen, Vice President of Smelting business line.