Kaolin is an industrial mineral that needs a very rigorous quality control, such as fine particles size and high brightness, to meet market quality. On the other hand, in the mineral industry, there is a lack of equipment capable of evaluating processes in actual time. In this work, chemical bleaching of one kaolin sample, in pulp, was evaluated. Three different tests were performed at the UFRGS laboratory and the results were compared to one industrially bleached sample. At present, the control of kaolin processing is accomplished by reflectance spectrum analysis using tablets prepared from dry ore samples. This type of analysis, besides being error sensitive in sample preparation and measurement, is very time consuming. The apparatus used in this work, for on-line characterization of mineral pulps, is an adapted version of the original Colorcell® equipment. Colorcell®, developed by the RENNER-HERRMANN Company, is used in the continuous production process of paints. A good linear data correlation was observed between the dry and wet optical methods of characterization. The results of this work possess a great application potential in industry, mainly, to reduce operational costs and improve quality of the final product.
Kaolin; process control; Colorcell; whiteness
