Uso de talco nacional como aditivo adsorvente de piches e materiais pegajosos no processo de fabricação do papel

Abstract

The subject of this study is the use of Brazilian talc as an additive for pitch and stickies control in paper industry, including technical and economical questions shared by raw material suppliers, as well as industrial consumers. Pitch and stickies refer to a large variety of organic and hydrophobic resins with undefined or unknown chemicalcomposition, that cause harmful deposits in paper pulp. These deposits occur during paper production causing problems to the process flow and quality damage to the final product. An efficient pitch control program is very important to achieve good operational results in the paper industry. Due to the property of talc to adsorb these organic resins, it is a common practice to add this mineral to paper pulps in order to reduce occurrence of pitch and stickies deposits. The Brazilian market has been supplied mainly by imported talc. Nowadays, the local suppliers are looking forincreasing talc use as a feasible technical and economical alternative to pitch control. The goal of this study was the comparison of national talc from Magnesitas mine in Brumado, Bahia State, with imported talc as a pitch and stickies control additive. The process to evaluate talc performance consisted in tests comparing pitch deposits formed before and after talc addition. The tests have been carried out using industrialand synthetic pulps. The developed method to evaluate pitch adsorption by infrared spectrometry is very important. It is a pioneering way to do this analysis and it could give more precise comparisons than the traditional industrial test by the hemacytometer. The main variables for the Brazilian talc studied were the different milling and micronization operations causing different values of superficial specific areas. The talc from Magnesitas mine presented good results comparing with the imported one. In tests with industrial pulps, the imported product indicated about 55% of pitch removed and the national one about 50%. In tests with synthetic pulp/synthetic pitch, the samples with larger specific surface areas showed best performances. Therefore, the performance of the national talc was superior considering equivalent surface areas. It has been proved that Brazilian talc is a good technical choice, and, hopefully, an economical alternative for the imported talc, as an additive for pitch and stickies control in the paper industry.