Talc's Multiple Functionality In The Paper Recycling Process

摘要

Talc, because of its strong organophilic nature has, over decades, been employed, successfully in paper mills in order to pacify both micro and macro stickies. More recently, additional features that give talc a unique, distinctive advantage-improved removal of stickies at the flotation and hydrocyclone cleaner stages as well as removal of detrimental organic impurities from the PM water circuit-have emerged. Collectively the separation processes in conjunction with pacification means that overall talc is an extremely efficient treatment for stickies and other hydrophobic substances capable to disturb paper making. In this presentation the well known pacification process is briefly reviewed and the additional benefits of talc in the pulp and paper production are considered. In the pacification step individual stickies particles are enveloped either partially or completely by talc. The thin layer of talc renders the pitch or sticky particle less tacky and significantly less prone to form deposits. Consequently the now innocuous contaminant leaves the paper machine with the finished paper. It has been empirically demonstrated that the inclusion of talc before flotation significantly improves the rate of stickies removal during this processing step. In the separation process in cleaners the sticky particle is again enveloped in talc. The thin layer of talc then serves to increase its size and importantly its density to a critical level where it is more readily removed by centrifugal force. In the paper machines water circuit finally the organophilic talc surface can actively help to remove detrimental, hydrophobic material that otherwise would disturb the sheet formation and strength properties.