Contact person
Erik Karlsson
Forskare
Contact ErikTroubleshooting in the chemical recovery at Kraft pulp mills
Chemical recovery ensures a resource‑efficient, circular use of forest raw materials by supporting operational reliability, energy efficiency and chemical balance. It also provides renewable energy and can be further developed to strengthen the bioeconomy and industrial competitiveness.
Support for process issues in chemical recovery
RISE supports pulp mills in the development, troubleshooting and optimisation of chemical recovery in the kraft process. The work covers the entire recovery cycle, with a particular focus on evaporation, causticising and chemical constraints such as scaling, precipitation and imbalances in the Na/S system. Our expertise is based on a combination of laboratory studies, advanced chemical analysis and mass balance simulation.
Evaporation – crystallisation and scaling
In evaporation, we address mechanisms of crystallisation and scaling, such as Na–SO₄–CO₃‑related salts, and how these are influenced by operating conditions, liquor composition and side streams. We have extensive experience from both laboratory work and industrial‑scale measurements, including mobile equipment for studies under real operating conditions.
Causticising and green liquor – chemical balance and NPEs
In causticising and green liquor handling, we analyse chemical equilibria, solid–liquid separation and how process changes affect chemical yield, quality and long‑term stability. A key aspect of our work is understanding and managing the accumulation of non‑process elements (NPEs), such as potassium and chloride, which can limit operational flexibility and cause corrosion or operational issues.
Mass balances and WinGEMS simulation
To place individual observations in a system‑wide context, we use mass balance simulations in WinGEMS. An established reference mill model enables evaluation of the effects of changes across the entire recovery system. Simulations are combined with experimental data and advanced chemical analysis techniques, such as liquor analysis, crystal phase identification and trace element determination, using RISE’s extensive analytical infrastructure.
By integrating laboratory work, chemical analysis and process simulation, we help pulp mills identify root causes, evaluate mitigation measures and make robust decisions for a more stable, efficient and flexible chemical recovery process.
How RISE creates value for pulp mills
- Reduced risk of scaling and operational disturbances
- Improved chemical balance and energy efficiency
- Reliable decision support for capacity increases and process modifications
