The technology for the preparation of polysulfide, and the digester modifications to enable production of the improved softwood pulp, were supplied by international technology Group 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, which 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.
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 also modified Joutseno’s cooking plant to optimize the new process.
About The ANDRITZ GROUP
The ANDRITZ GROUP (andritz.com) is a globally leading supplier of plants, equipment, and services for hydropower stations, the pulp and paper industry, the metalworking and steel industries, and solid/liquid separation in the municipal and industrial sectors. In addition, ANDRITZ offers technologies for certain other sectors including automation, the production of animal feed and biomass pellets, pumps, machinery for nonwovens and plastic films, steam boiler plants, biomass boilers and gasification plants for energy generation, flue gas cleaning plants, plants for the production of panelboards (MDF), thermal sludge utilization, and biomass torrefaction plants. The publicly listed, international technology Group is headquartered in Graz, Austria, and has a staff of around 23,700 employees. ANDRITZ operates over 220 production sites as well as service and sales companies all around the world.
About ANDRITZ PULP & PAPER
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. The service range includes modernization, rebuilds, spare and wear parts, service and maintenance, as well as machine transfer and second-hand equipment. Biomass, steam, and recovery boilers, gasification plants for energy production, flue gas cleaning plants, production equipment for biofuel (second generation) and biomass pelleting, biomass torrefaction, and plants for the production of nonwovens, dissolving pulp, plastic films, and panelboards (MDF) are also allocated to the business area.