Austria-headed international technology group Andritz AG has announced the successful completion of two screw press upgrades for Finland-headed forest industry major Metsä Group. The upgrades were carried out at Metsä Board's Joutseno Mill in Finland.
Metsä Board is a leading European producer of premium fresh fibre paperboards, including folding boxboards, food service boards, and white kraftliners. The Joutseno mill produces BCTMP for Metsä Board’s own board mills and has a production capacity of 320 000 tonnes per annum.
The rebuild of both screw presses (#21 and #22) included installation of a new Low-Energy Screw Shaft (LESS) as well as split grooved baskets for the medium-pressure zone in order to widen the operating window of the presses and allow higher production rates.
According to Andritz, the design of the LESS enables a new compression curve, resulting in a higher throughput at the same installed power.
The screw press upgrades are part of the step-by-step optimization of the BCTMP (bleached chemical-thermomechanical pulp) process that is currently in progress, with the overall aim of improving the availability of the plant. Press #21 is used as a wash press, and press #22 acts as a secondary stage in the washing process.
