Caracterização textural, mineralógica e a lavra de aluviões diamantíferos nos garimpos da chapada diamantina, Bahia / Textural and mineralogical characterization and the mining of diamond-bearing alluvial deposits in the chapada diamantina, Bahia

Abstract

Diamond prospectors, who have been mining for more than 150 years in the Chapada Diamantina, are now trying, through initiatives such as the Andaraí prospectors cooperative, to formalize the exploitation of the diamond alluvial deposits in this region of Bahia. The sequence of operations for mining and processing these alluvial deposits in semi-mechanized garimpos, is generally determined by the geological conditions of the deposit and the availability of water resources. This research contributed to the characterization of secondary diamond deposits and to the understanding of how the mining of these deposits occurs in the Chapada Diamantina. It evidenced the characteristic profile of these alluvial deposits that present the diamondiferous gravels accumulated at the base of the sedimentary sequences, sterile matter formed predominantly by sand and clay, a configuration very similar to that observed in the deposits found in the tributaries of the Paraguaçu River, present in the study area. The main objective of this paper was to conduct a mineralogical and textural characterization of the alluvial deposits in the municipality of Andaraí in the vicinity of the Paraguaçu River and of the operational conditions of mining by the miners. The results point to a high sterile-mineral ratio for the exploitation of these deposits and detail the processes of mining and treatment of the diamond gravel for concentration of the Diamonds.