Caracterização e processamento mineral da barita de contendas do sicorá – Bahia - Brazil

Abstract

Barite is a barium sulphate mineral (BaSO4) with high specific weight (4.5 g/cm3). It is specially used as a drilling fluid in oil and gas exploration, to suppress high formation pressures and to prevent blowouts. Two samples of Contendas of Sincorá – Bahia State – Brazil, were studied in order to develop a mineral processing route to recover barite. The mineral characterization (X-ray fluorescence and X-ray diffractometry analysis) revealed that the samples are composed respectively of 55 and 75% of barite; however, their SiO2 contents were considered high, varying from 40 to 25% (weight %). A gravity separation process was proposed due to the large difference of specific weights between quartz and barite with values of 2.65 and 4.5, respectively. The sinking and floating tests were performed on the ore sieved at screen of 6.35, 1.19 and 0.149 mm. Bromoform was used as a heavy liquid (2.89 g mL-1). The results showed that 90% of the material was concentrated in the sunk product, suggesting that quartz is still associated to barite, probably by liberation problems. Therefore, the samples were crushed to <0.149 mm (100# Tyler) and submitted to froth flotation tests. The reverse flotation of quartz did not reveal good results since quartz was still associated to barite in the depressed product. Thus, a direct froth flotation of barite was carried out and the results showed an improvement of the barite concentrate. The metallurgical recoveries obtained were 64 and 76% (weight percent) with 82% and 85% of barite content.