Alternativas para otimização do processo de beneficiamento de caulim da região Seridó dos Estados da Paraíba e do Rio Grande do Norte.

Abstract

Kaolin is a white rock, formed by hydrated aluminum silicates, due to its technological characteristics it has a wide industrial application. Kaolin deposits are geologically classified into two types, according to origin: primary kaolin deposit and secondary kaolin deposit. Normally, this mineral is associated with impurities, so it is necessary to go through beneficiation processes to meet market specifications. Kaolin processing can be done dry or wet. In these processes there is a large generation of waste, which is disposed of on the company's own land, occupying a large amount of space. The kaolin in the Seridó da Paraíba and Rio Grande do Norte regions is of the primary type, formed by the alteration of pre-existing pegmatites and its processing is carried out wet, generating two types of tailings. Much of the extracted material is disposed of in tailings piles after processing. In this context, the main objective of this work is to propose alternatives for optimizing the kaolin processing process, replacing equipment and methods, mainly in the disaggregation and classification stages. The methodology comprised the stages of sample collection at Mineração Norway, located in the municipality of Junco do Seridó – PB; technological and mineralogical characterization through DRX, FRX, MEV, DTA, TG; particle size analysis; disaggregation and dispersion through attrition test and bench hydrocyclone tests. In addition to the simulation stage, the specific application for mineral processing, the USIM PAC, was used. The results of the characterization determined that the samples have similar chemical and mineralogical composition, being composed of quartz, muscovite, microcline and predominantly kaolinite, even with the tailings containing very high contents of kaolinite (80%). The results of the attrition tests show that the best attrition conditions for kaolin dispersion were with 20% percentage of solids in the pulp, with a stirring speed of 1000 rpm and a stirring time of 30 min, obtaining the degree of dispersion equal to 47, 12% and it was still possible to determine that agitation speed values between 500 and 1000 rpm would be considered ideal for kaolin dispersion. The hydrocycloning tests indicated promising results for the classification of this type of kaolin, but a good adjustment of the operational variables is needed. The best results were found in the T4 and T6 tests, which presented lower D50 values and the FRX results showed that the aluminum oxide contents are higher in the overflow and the silica contents are higher in the underflow. The hydrocyclone simulations indicated that the pass values in the 200 mesh were above 99% at the overflow output. It is concluded that the kaolin processing process in the Seridó Region can be improved and optimized by modifying several points in the process, from the inclusion of a better disaggregation process in the feeding stage, as well as the replacement of the conventional classification method by sieves, by classification using hydrocyclone.