Metsä Fibre Starts-up Polysulfide Cooking Line at Joutseno Pulp Mill

Andritz polysulfide technology for Metsä Fibre's Joutseno pulp mill in Finland.

July 8, 2013 - Andritz said that Metsä Fibre's Joutseno mill in Finland has started up the world's largest single polysulfide cooking line.

The technology for the preparation of polysulfide, and the digester modifications to enable production of the improved softwood pulp, were supplied by Andritz.

According to Joutseno Mill Manager Risto Joronen, who was also the director for this development project with Andritz, the use of polysulfide cooking liquor enables the mill to improve certain pulp qualities that benefits papermakers. One of those benefits is a reduction in specific energy to refine the pulp, resulting in lower operating costs for papermakers. There are also some enhancements to the fiber bonding due to the retention of certain hemicellulose materials in the pulp.

The Joutseno mill is also increasing its fiber yield, which makes the investment economically beneficial. As a result, the mill is able to reduce the loading of its recovery boiler which allows it to improve production capacity, Andritz noted.

According to Andritz, the polysulfide process modifies conventional white cooking liquor to “orange liquor” (named due to the characteristic color of the modified liquor) by oxidizing sodium sulfide in the liquor to polysulfide.

The plant provided by Andritz is based on the proven MOXY process (white liquor sulfide-to-polysulfide conversion), already installed in several mills around the world.

The Joutseno mill is by far the largest single unit in operation worldwide, Andritz added.

Andritz also modified Joutseno's cooking plant to optimize the new process.

The Joutseno mill is the world’s largest single-line softwood pulp mill and has the capacity to produce 670,000 tonnes per year of ECF (Elemental Chlorine Free) bleached softwood pulp.

Andritz Pulp & Paper is a leading global supplier of equipment, systems, and services for the production and processing of all types of pulps, paper, tissue, and board. The technologies cover processing of logs, annual fibers, and waste paper, production of chemical pulp, mechanical pulp, and recycled fibers, recovery and reuse of chemicals, preparation of paper machine furnish, production of paper, tissue, and board, calendering and coating of paper, as well as treatment of reject materials and sludge. For more information visit:

SOURCE: Andritz