Quicklime plays a central role in the closed chemical circulation of a modern pulp mill. Thanks to lime, the chemicals used in the cooking process can be circulated in a pulp mill’s recycling line, which decreases the environmental impact. Pure and homogeneous lime and reliable deliveries are expected from lime suppliers as momentary peaks in the volume requirement can be significant.
About 250 kg of quicklime is needed in the production of a tonne of pulp. Normally, 3 to 4 per cent is replaced by new lime, as the main part of the lime is reused in the recycling of chemicals.
The pulp industry also uses lime products in effluent treatment. For this purpose Nordkalk produces quicklime, slaked lime and limestone powder.
The paper and cardboard industries use lime-based coating pigments and fillers such as GCC (Ground Calcium Carbonate). GCC is made from concentrated and fine-ground calcium carbonate and used to make fine paper, cardboard packaging and pulp-based paper.
The calcite for GCC is manufactured in Lappeenranta, Finland, where the local marble is extremely white. The producer of GCC in Lappeenranta is Nordkalk’s subsidiary Suomen Karbonaatti Oy.
PCC (Precipitated Calcium Carbonate) is made from quicklime. It is mainly used as filler in fine paper such as copy paper, in which brightness and opacity are important qualities.
