Community Research and Development Information Service - CORDIS

Closed cycle mill for high quality bleached chemical pulp

An ecologically balanced mill, where the total production process from wood to finished product, is integrated in a closed cycle is now possible. In this case all mill residues and waste products are used for energy generation and ashes and inorganic residues are brought back to the forest. New production methods involving closed processes have been developed.

The results of the project show that recycling of organic matter is possible in the membrane separation and/or evaporation processes. Some mills are using these techniques but, until now, only for specific cases. The work performed in our project must be useful to extend the application of evaporation and membrane separation and manufacturers are already interested.

The behaviour of non-process elements in the recovery system has been studied when bleach plant filtrates are recycled. Although not directly creating new products, the pulp industry in Finland and in Sweden in presently using this knowledge in developing pulp mills towards closed cycle operation leading to minimum environmental impact. For example, a new pulp mill, which is just starting, will use the gathered knowledge for recycling its bleach plant filtrates, partially to the chemical recovery systems of the mill, and furthermore aiming in future to recycle all its bleach plant filtrates. Other mills in Scandinavia and in France are also considering recycling of bleach plant filtrates as a serious process alternative in future operations.

The knowledge and skill created during the project will be used by KCL, when assisting the pulp industry in developing closed cycle technology and consulting companies in the identification of possible process problems, and in solving these problems. As owners of KCL the Finnish pulp and paper companies, have the highest priority for the consulting services, but other European companies are not excluded.

During the project, a new process idea for removing non-process elements from bleach plant filtrates was developed. This process, for which a patent was applied, will be further developed in close cooperation with the Finnish pulp producers to achieve a feasible process. In addition, a new technique to produce pure recyclable water from bleach plant filtrates was tested. This technique was earlier invented and is own by A. AHLSTROM Corporation, which is continuously developing it and offering it as mill-scale installations.

Reported by

Centre Technique du Papier
Domaine Universitaire
38044 Grenoble
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