Stronger together: Metso Outotec develops Flash Smelting technology alongside customers to achieve optimal results

The Metso Outotec Flash Smelting process has an operating history of over 70 years. Due to this impressive feat, feedback from numerous operating sites is available, so development work is often carried out in cooperation with our customers. Throughout the years, Metso Outotec has been developing the Flash Smelting technology together with customers in order to maximize results. Recent developments include optimizing the enriched air distribution to the burner air chamber and discharge outlet, optimizing the feed distribution to the burner outlet, as well as adding a monitoring system (FlashGuard) to ensure that the burner stays in optimal condition.

The power of working together: Advancing our equipment with the latest information

Uneven process air distribution in the concentrate burner has a negative impact on the smelter performance, as was seen in the Atlantic Copper Flash Smelting Furnace in Huelva, Spain. The old gas channel feeding process air to the burner was highly asymmetric and the air chamber was designed for lower gas flow, which was seen as uneven heat load to the reaction shaft walls.

A comprehensive evaluation of the entire burner design - including the enriched process air supply - was made. This consisted of a CFD study and a redesign of the process air ductwork together with an upgrade of the burner, which was installed in 2017.

The impacts from the change are already evident. The mass flow distribution of process air has improved significantly at the burner outlet. This results in a lower oxygen coefficient of the process, thus improving oxygen efficiency.

Based on CFD modelling, we have found that it is also possible to improve process air distribution even further by changing process air duct orientation at the air chamber entrance, as well as utilizing additional guide plates inside the air chamber. This is a feature incorporated into the latest air chamber designs.

Practice makes perfect: Full scale workshop tests to gain additional insights

To further optimize the feed distribution around the burner discharge, several workshop cold tests were carried out on a full-scale distributor. The distributor was equipped with several expanding and contracting guides to even out the material before the cone. The material was collected into an annular collecting device below the distributor, which was divided into 16 sectors.

For the final test, a feed rate of 55t/h was fed to half of the distributor (110 t/h in total). After optimizing the geometry, test results achieved were within +-1.4% units from average. Similar tests were also made using a setup feeding only from one side using an air slide with a feed rate of 132-138 t/h, test results achieved for that setup were within +-1.2 %-units from average.

As a frontrunner in the industry with regards to research and development, Metso Outotec has the capabilities and industry know-how to initiate the appropriate tests in order to maximize the productions of our customers. It is these trusted customers that allow this valuable information sharing and feedback loop so we can develop and upgrade their equipment together.

Observable benefits are demonstrated: New burner distributor installed

As part of an improvement project around the concentrate burner, the new optimized distributor was installed in 2020 at the Atlantic Copper Flash Smelting Furnace in Huelva, Spain. Data was collected from the new distributor, and then compared with periods when the old distributor was in use. Additionally, 3 different distributor air rings were also tested on the new distributor during different time periods between May 2020 – April 2022.

The data period for the new distributor version 1 (staggered) consisted of several intervals between May 2020 – November 2021, with a total time period of 8.5 months. The data period for the new distributor version 2 (aligned) consisted of several intervals between June 2021 – April 2022, a total time period of 7 months. Finally, the time period for the new distribution version 3 (swirl) consisted of just one period between May 2021 and June 2021, with data collection only spanning 13 days. (Note: This is too short of a time to be able to draw reliable conclusions).

Feed rate and dust feed were also compared, as well as oxygen coefficient, off-gas line parameters, reaction shaft and settler heat load distribution, matte and slag analysis.

Benefits from the new distributors included:

• Significant improvements for slag Cu as it’s % reduction lowers slag Cu losses of the process
• The improved evenness of the reaction shaft and settler heat loads improve the lifetime of the furnace by stabilizing the protective buildup layer inside the furnace
• V1 staggered is better than V2 aligned distributor (V3 swirl in use for too short of a time to make final conclusions)

FlashGuard: Maintaining successful burner performance

Now that the benefits of research and development have been established, it is important to highlight the significance of maintaining the performance in order to ensure optimal conditions after time. A monitoring system (such as Metso Outotec FlashGuard) is beneficial to monitor alignment and build-up conditions around the burner. The FlashGuard system includes 3 or 4 cameras with monitoring software that help in build-up detection and alignment monitoring. This system makes burner alignment simple, and allows for good control and increased online availability.

There’s strength in partnerships

The consistent collaboration between Metso Outotec and our customers allows for beneficial research and development to be successfully completed. This particular development work performed for the process air and concentrate distribution highlighted excellent equivalence between CFD modelling, full scale test work and tangible operational results.

By using the new optimized distributor, the benefits such as improved process air and feed distribution, reduction of oxygen coefficient, improved furnace lifetime, lower slag Cu losses, better evenness of the reaction shaft, and many more become a reality for customers. It is this reliable and trusted feedback loop that allows us to continuously develop our portfolio to further improve your processes. With valuable information sharing and expert research capabilities, we are able to create the equipment to best suit your specific needs. That’s why, together, we are the partner for positive change.

This article is part of our Smelting Newsletter 2022. Visit the issue front page for all articles and greetings from Jyrki Makkonen, Vice President of Smelting business line.