Caracterização e processamento de vermiculitas da Paraíba.

Abstract

This work aimed at the technological characterization of samples of verniculite ores of Paraiba, in terms of chemical and mineralogical composition, concentration, with special prominence for the process of thermal exfoliation. The samples selected for the present study proceed of the ore body of vermiculite of Santa Luzia and of the occurrence of Casserengue. In the concentration experiments, the ores were separate in grain sizes, which the gravity concentration was submitted and/or magnetic separation. In the exfoliation, it was studied the influence of some parameters relevant to the process, such as: grain size of material, residence time and temperature. The results showed that in Santa Luzia's ore, the vermiculite was identified in plates or in particles as well as composing plates with intercrustal of vermiculite and biotite. This vermiculite comes with little mineralogical uniformity and high alteration degree; however, these characteristics little affect their exfoliation properties. In the Casserengue ore, the predominant mineral is the biotite, and the vermiculite meets in smaller proportions. Because of the low vermiculite grade, the Casserengue ore does not possess potentiality of industrial application. Were carried out processing, test with samples of Santa Luzia these results were compared with dates obtained for the vermiculite of Queimada Nova from Piaui state. The results of the tests of gravity concentration and magnetic separation made with samples of Santa Luzia's ore, they indicated that both processes were appropriate for the processing of the fractions (-1+0,5) mm and (-0,5+0,3) mm. The exfoliation results showed, as it was waited, that for the optimization of the process it is necessary the simultaneous control of the size of the material, temperature of the furnace and of the residence time of the particles in the furnace. It was verified that Santa Luzia's vermiculite came inferior in terms of exfoliation capacity, in comparison with the vermiculite of Queimada Nova These differences are due the variation in the chemical and mineralogical composition as well as to the degree of interlayers of vermiculite and biotite.