Chloride and Potassium removal with Valmet Ash Treatment

Valmet's ash treatment systems remove Chloride and Potassium from the recovery boiler ESP ash. Valmet has built ash treatment systems in pulp mills all over the world. Several have been upgraded as the mills have increased production.

Chloride and Potassium

Chloride and Potassium can enter the mill with incoming wood and water. The two chemicals change the properties of recovery boiler ash, and this can lead to problems.

The ash can become sticky and hard to remove by sootblowing. Sometimes this leads to a buildup of ash that plugs the recovery boiler and makes it necessary to stop it for water washing. And if the superheaters corrode, Chloride and Potassium may be part of the problem.

Valmet solutions

An ash treatment system from Valmet removes Chloride and Potassium from the liquor cycle. This can lead to increased uptime and production.

Valmet offers three solutions that bring different benefits. The solutions are well proven and several mills have returned to Valmet to increase the capacity of their original installation as the mill has expanded.

The working principle

Valmet's technology uses water to separate Chloride and Potassium from the other chemicals in electrostatic precipitator (ESP) ash.

When ESP ash is mixed with water, Chloride and Potassium dissolve, while the pulping chemicals remain as solids. The solids can be separated from the liquid and returned to the mill while the liquid, with the unwanted chemicals, can be led to wastewater treatment.

This is the basic mechanism of the two main technologies on the market today, ash leaching and ash crystallization.



The Valmet ash treatment systems perfom very close to the theoretical maximum limit. Valmet's ash crystallizers, for example, offer up to 96% removal of Chloride. Since the cooking chemicals are valuable, having a high rate of recovery is also an important measurement of an ash treatment system. 

Rates of removal and recovery will differ depending on the content of the mill's ESP ash. And these levels can also vary over time. This is why a good ash treatment system is not only about the theoretical maximum performance, but also about having the capacity to handle variations and perform well for a long time.

Our expertise is at your service

Our expertise is at your service

Our focus is to bring your performance forward utilizing our extensive experience and in-depth knowledge of pulp process technology. Get in touch with our experts through your local Valmet office, or the link below.

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