Valmet ash crystallizer will help Mercer Stendal pulp mill reduce emissions

Valmet Oyj reported May 19 that it will deliver a new ash crystallization plant at Mercer’s Stendal mill in Arneburg, Germany. This investment is part of Mercer’s long-term vision to further reduce the mill’s emissions and improve its performance. Ash crystallization will help close the mill’s chemical-circulation process, reducing the need for makeup chemicals, and extending recovery boiler maintenance intervals to 24 months or more.

This mill has a capacity of 740,000 tonnes per year of bleached softwood kraft pulp. Its new ash crystallizer will be integrated with its evaporation plant, where it will be able to process 140 tonnes of ash per day. It’s scheduled to start operating in 4Q27.

“Since the mill started in 2004, we’ve invested in improving its performance and sustainability. Our sustainability efforts are guided by Mercer’s vision and values and our longstanding philosophy of responsible business practices that encompass sustainability, safety, financial responsibility and strong leadership,” says Dr. Martin Zenker, mill manager at Mercer Stendal. “This ash crystallization plant will help us further improve operational and environmental performance.”

Valmet’s contribution covers the complete plant, including electrical and instrumentation systems (E&I), steel structures and construction. It will also expand the mill’s existing, plantwide Valmet DNA automation system.

The ash crystallization plant will recover valuable sodium salts, and remove non-process elements, mostly chloride and potassium, from the mill’s liquor cycle. This will reduce plugging and corrosion in the mill’s recovery boiler, which is how it will achieve longer maintenance intervals. Removing these non-process elements with Valmet’s ash crystallizer design will also eliminates ash dumping, which reduces wastewater, demand for the  makeup chemicals and related emissions.

“We’re committed to advancing circularity and resource efficiency. Delivering a new ash crystallization solution to an existing mill is very much in line with these targets and brings several operational and environmental benefits,” says Claus Jensen-Holm, director of white liquor and evaporation for pulp mills at Valmet. “This project show that ash crystallization isn’t only suitable for new large mills, but also benefits existing mills. We value our cooperation with Mercer and the Stendal mill in finding long-term solutions to optimize its performance.”