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Ash leaching and crystallization solutions

Valmet offers three solutions that treat the ash from the electrostatic precipitator. The optimal solution always depends on each mill’s operating conditions.

Chlorides and potassium that enter the liquor cycle with the raw material can cause corrosion in the liquor cycle, for example, in the digester, the evaporators and the recovery boiler. In the recovery boiler, too high concentrations of chlorides and potassium can lead to plugging, increased consumption of soot blowing steam and reduced efficiency in the electrostatic precipitator.

These non-process elements are enriched in the ash from the electrostatic precipitator. Systems that remove them should do so while maximizing the recovery of sodium and sulfate, which are valuable cooking chemicals.

Valmet offers three solutions that treat the ash from the electrostatic precipitator. The optimal solution always depends on each mill’s operating conditions.

AshLeach

AshLeach is a well-proven, uniquely simple and effective system to remove chlorides and potassium. It does not require steam to operate and can run independently of the other chemical recovery systems.

This ash leaching system has been providing outstanding value for pulp producers ever since the start of the first unit in 2002. Currently, there are systems up and running all around the globe at mills that produce pulp from eucalyptus, acacia, pine and other wood species. Thanks to the simplicity of its process, an AshLeach plant is very easy to maintain and operate. AshLeach stands for high availability and good long-term performance.

AshLeach Duo

AshLeach Duo is a two-step ash leaching solution that is very effective when cleaning ash with high carbonate content.

Ash Crystallization

In Ash Crystallization, the ash is completely dissolved in water and the solution is evaporated. The resulting crystals of sodium sulfate or carbonate are removed and returned to the liquor cycle. The evaporation step consumes process steam, but the crystallization process offers higher recovery and removal rates than processes based on leaching the ash.