Technical Note

Online color control of Brazilian kaolin pulps on the bleaching process

J.J. Varela1,*, R. Gliese1, C.A. Peixoto2 and C.O. Petter1

1 Laboratório de Processamento Mineral, Escola de Engenharia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
2 Núcleo de Tecnologia de Produção - Renner Herrmann, Gravataí, RS, Brazil

Accepted 26 March 2005


In the global market, all the industrial sectors are forced to adapt the product specification to more rigorous control parameters. The worldwide tendency is headed toward product color becoming a fundamental parameter for market acceptance. In this context, one of the difficulties in the Brazilian industry is the lack of suitable equipment for measuring the reflectance spectra of mineral pulps during the processing. A typical case is the use of brightness and yellowness indexes in industrial minerals industry. The apparatus used in this work, for online characterization of mineral pulps, is an adapted version of the original Colorcell® equipment. Colorcell® is one equipment originally developed by the Renner Herrmann company for use in paint production. Tests were carried out with kaolin from Pantano Grande, Rio Grande do Sul, Brazil. The samples of pulp were characterized through the L* a* b* system, ISO brightness and E313-00 yellowness indexes. Comparing the colorimetric results of the Colorcell® with the conventional method of measuring tablets, the Colorcell® data are more saturated. Colorcell® results have a good correspondence, stability and reproducibility when it is compared with conventional method (dry tablets). By means of the obtained results, the Colorcell® technology is pointed as an excellent application in the control of the industrial minerals processing. The online control of plants with the Colorcell® system has a great potential to process optimization.

Keywords: Kaolin, Bleaching, Brightness, Process control

* Corresponding author
   E-mail : varela@ct.ufrgs.br