IN-LINE PCC TECHNOLOGY CLEANS UP CIRCULATION WATER FROM DISSOLVED MATERIALS, METALS AND BIO BASED MICROORGANISMS RESULTING TO CLEAN PROCESS AND HIGH RUNNABILITY

摘要

In-line filler process produces high quality calcium carbonate filler for paper and board production. The process creates precipitated calcium carbonate crystal - fiber composites with strong mechanical bonding of PCC filler particles to surfaces of fibers and fibrils. Process is integrated directly to paper/board machine short circulation. With flash mixing injection technology gaseous carbon dioxide is dispersed into micro-bubbles and milk of lime slurry are dissolved instantly into process water resulting extremely fast PCC crystallization onto particles of stock flow. Results from fine paper machines in Europe producing high quality special grades have proved that flash mixing resulting to fast PCC crystallization reaction binds effectively fine particles as well as dissolved and colloidal material from process water. This material is fixed to paper web resulting to cleaner process with good runnability with high optical paper qualities. The comparison to conventional standard scalenohedral show that in a laboratory burned paper ash color of In- line filler PCC is brown compared to paper of standard PCC. Elemental EDS-analysis of burned paper ash samples showed significant differences. In-line filler PCC ash contains very high amounts of different metals. Especially high adhesion of iron to In-line filler PCC crystals causes the change in ash color. All dissolved process water compounds are attached to paper web resulting cleaner water circulation with better machine runnability and longer life time of machine fabrics because of high filler retention. The similar effect takes place also with microorganisms of stock flow. Bacteria population is reduced 80% from its original level after In-line filler reactor. The technology makes it possible to reduce microorganisms populated e.g. in recycled fiber material or in circulation waters. The same effect can be exploited to eliminate seasonal quality changes entering the mill environment with raw fresh water.