Beschreibung:
<jats:p>Pitch deposition in pulp or in different parts of the manufacturing system can lead to a decrease in the quality of the final paper produced and to manufacturing efficiency problems. One of the methods to control pitch deposition is the use of talc. Talc acts primarily as a detackifier and must be part of the deposit to control further deposition. The effectiveness of talc as a control agent depends on its structural and surface characteristics (e.g., specific surface, surface energy, surface charge, and ratio of lypophilic to hydrophilic surface), which are related to its mineral composition and the thermal and surface treatments it has undergone. For this study, we tested five commercial talcs, corresponding to two groups of different mineralogical compositions, to determine their detackification capacity using a deposition tester developed by the Complutense University of Madrid, Spain. In this method, the quantification of the deposits is carried out by an image analysis of stainless steel collectors on which the deposit has formed. After image analysis, a qualitative analysis to determine the deposit organic fraction is carried out by gas chromatography after deposit extraction. The detackification capacity is expressed as the reduction of the deposits formed on the collectors when the different talcs at several concentrations are added to the pulp suspensions. The results show that pitch detackiness by talc addition is related to talc concentration and mineral surface properties, as for example, chlorite proportion, surface area, and surface treatment, and to the adsorption capacity of pitch on talcs. In general, the talc having the highest quantity of mineral talc presents the best detackification capability, and the detackification of all talcs studied was appreciably reduced at low proportion of addition.</jats:p>