Metso develops Opex and Capex comparison methodology for copper smelters

To address the high demand and often conflicting published information, Metso has developed a tool for quick scenario comparison. This tool integrates Metso expertise and publicly available operational data from different modern copper smelting technologies into a single process model calculation framework. The modeling tool used is the Metso HSC chemistry simulation package, which allows for efficient flowsheet simulation with accurate thermochemical balance across various metallurgical operations. The goal is to provide an easy comparison of each modern smelting technology by inputting the main parameters, generating results with a single click.

The calculations are based on comparable inputs and outputs for each technology. For smelters, this means using the same feed mixture and utility properties. The model is designed so that changing one parameter affects all flowsheets, simplifying the study and comparison of the effects of changes.

A data-driven approach to smelter efficiency

Operational cost comparisons have been published in two articles at the latest Copper conferences in 2019 and 2022. Additionally, they were complemented by articles on electrical consumption (COM 2017) as well as environmental footprint (Cleaner Environmental Systems 2021). The HSC simulation package was found to be a suitable tool for all of these comparisons.

The main Opex drivers identified were the costs of technical oxygen, electricity and labor, all of which are location-dependent. The comparison revealed that the cost of downtime and copper losses can vary by up to 20% depending on the technology chosen, in terms of cost per tonne of copper produced. Size matters, as higher capacity smelters were consistently found to be more cost-efficient per unit of produced cathode copper.

Flash Smelting with Flash Converting or Peirce-Smith converting was found to be the most cost-efficient across all calculated capacities and feed grades, followed by TSL technology.

The model—originally developed for process comparison and cost calculation—was further developed to include the environmental performance of different smelting methods. The results, which were published in a scientific journal and described in the Smelting Newsletter 2021, showed that Flash Smelting combined with PS converting had the lowest carbon dioxide emissions by a small margin, whereas Flash Smelting and Converting is superior in terms of sulfur dioxide. The highest impact on carbon footprint was found to be the electricity production including electricity used in the oxygen plant which had a high carbon intensity when using the global average.

From insights to innovation: Shaping the future of smelter cost methodologies

The developed tool for Opex calculation can evaluate the impact of different factors on the overall cost level of copper smelter operations, as well as the influence of local costs, especially when considering the location of a new smelter. Additionally, Metso has identified and worked on potential improvements in flowsheets, both economically and environmentally, and the work continues.

In addition to the continuous development of the tool and supporting customers’ decision-making with its results, the aim is to further develop the estimation methodology for Capex, integrating it with smelter development. This capex calculation will include the costs from the original engineering all the way to the site development and plant erection to capture the full cost of implementing a major project in practice. This is an exciting addition to the series of our articles and the summary will be published at the upcoming Copper 2025 conference.

Eventually, Metso hopes to combine Opex and Capex estimations into a single, thermodynamic model-based estimation tool which can produce pre-feasibility level NPV calculations without the need for excessive engineering studies. With strong R&D and innovation power, Metso is continuously looking for new ways to introduce innovations for the customers’ benefit. That’s why, together, we are the partner for positive change.

This article is part of our Smelting Newsletter 2024. Visit the issue front page for all articles and greetings from Jyrki Makkonen - VP, Smelting.