Profitable and sustainable Smelting

 Lauri Närhi, Director Sales     Mikael Jåfs, Director Strategic Projects and Innovations

The need to tackle climate change and pollution is changing the game in the traditional and conservative field of smelting.

Smelting processes are traditionally energy-intensive. The processes often utilize the heat content of the raw materials, such as sulfur and iron in the oxidizing stages of processing, but also include stages where the oxides need to be reduced through the use of reductants such as carbon-based materials. Hence, the process flowsheet and operating practices have a large impact on the sustainability and production cost of the metals.

Efficiency and profitability have always been a driving force in the field. However, today, customers are also focusing on the ecological and social sustainability of production and products. Laws and social pressure are demanding companies to search for sustainable solutions to legitimize their existence, the license to operate. The good news is that efficient is often also sustainable.

Compared with competing technologies the Outotec process and technology portfolio ranks at the top in terms of low emissions, high energy efficiency, and safety.

The results of a recent comparison of seven processing routes to produce copper from primary raw materials was just published at COM hosting Copper 2019 in Vancouver [1]. The simulations of different scenarios showed that Outotec Flash and TSL technologies rank at the top in terms of operating cost. Also, the flowsheet selection affected how sustainable the production remained through the lifetime of the plant.

The Outotec Flash Smelting Process gives you high recovery of metals with at the lowest total cost of ownership. The flash smelting technology was developed already 70 years ago. However, the technology has been developed intensively and has come far since its early days giving operators a lot more flexibility and possibilities for optimizing the process than before.

With more than 60 installations worldwide the Outotec Ausmelt TSL® process works with a variety of primary, secondary, and waste feed materials and fits especially well with the demands of a developing circular economy.

Aiming for zero emissions

Outotec’s long-term target in smelting is to achieve zero emissions. We are not there yet, but it is something we are constantly aiming for, step by step. The expectations for the technologies are becoming more demanding and the regulation is moving forward fast.

When before it was enough to clean the off-gases to reduce emissions, nowadays it is expected that gas emissions can be either reused or made into products of their own.

A good example is the gas stream from a ferrochrome smelting plant, which consists of carbon monoxide that can be used to produce electricity. A new innovation is to use carbon monoxide to produce chemicals, like glycol. This means the emissions never enter the atmosphere at all.

Outotec has a wide portfolio in non-ferrous off-gas cleaning and acid plants for production from primary and secondary raw materials. In copper smelting, we calculate that our handprint in cumulative avoiding Sulphur emissions exceeds 100 million tons over the years. The Outotec portfolio also includes a variety of solutions for dealing with off-gases from ferroalloy production targeting to minimize the emission and to capture as much value as possible from these side streams.

Fully Automated smelter improving productivity and safety

Working at a smelter close to molten metals and high temperatures can be extremely dangerous. However, efficiency and flexibility of operations can be significantly improved by modern process control. The Smelting team at Outotec has been developing equipment and digital tools to enable operating the smelter fully automatically.

It is a high priority for smelters to keep employees safe and improve their operations. The fully automated smelter could be described as a portfolio of solutions.

The fully automated smelter includes new ways to enhance process control using intelligent automation and methods for improving safety by removing operators from high-risk areas. 

As it is not likely that all plants would fully automate the entire smelter at once, we have approached this by creating modular solutions and tools to give our customers the opportunity to focus on the prospects with the best return on investment in the short-term. We are doing this in close co-operation with our customers and utilize co-creation and fast prototyping to develop solutions that match the needs of the operators and can be easily applied to their production.

As an example, automating punching machine operations in Peirce-Smith converters, i.e. the task of cleaning the tuyeres in the converter and doing so at the right time, is something you can easily automate and simultaneously improve operations with. Another great example is the suite of Process Advisors, with over a dozen references already. It acts on behalf of the operator to determine optimal parameters for the process and automatically write the setpoints to the automation system.

Outotec automated punching machine for Peirce-Smith converters
Outotec Process Advisor for Flash Smelting

Automating operations at smelters is going to be the future. Safety of employees is the number one priority and at the same time companies are finding it ever harder to recruit and retain skilled people to often remote locations. To tackle this challenge smelters need to align with the expectations of today’s workforce.

[1] Pesonen, L., Bunjaku, A., Johto, H., “Detailed OPEX Comparision of Modern Copper Smelting Technologies Using HSC-SIM Modelling”, Proceedings of the 58th Annual Conference of Metallurgists (COM) hosting the 10th International Copper Conference 2019, ISBN: 978-1-926872-44-5.