Upgrading graphite quality from Chenjere-Ruangwa ore through froth flotation techniques

Abstract

Tanzania is endowed with graphite deposits found in Mahenge-Morogoro, Bunyu-Mtwara, Nachu and Chenjere-Ruangwa. In Chenjere, the graphite resource is approximately 500 million metric tons with 7.75% of total graphitic carbon grade (TGC) content.  The demand in the global market needs a high-grade graphite of at least 90% TGC content. However, the graphite found in Chenjere is of low grade (7.75%). The present study aims to upgrade Chenjere’s graphite to meet global market standards.  To attain this objective, froth flotation was selected as an upgrading method. The sample was collected at Chenjere-Ruangwa, well prepared, and later upgraded through flotation. Flotation experiments were designed using the Box Behnken design, with controlled variables being particle size, collector, and frother concentrations while the TGC was the response. The analysis of variance (ANOVA) was utilized to assess the relationship between the experimental factors and model response. The results revealed that the graphite from Chenjere can be upgraded to > 90% TGC content under the optimal experimental conditions of -75 µm particle size, 990 g/t kerosene as a collector, and 150 g/t methyl isobutyl carbinol (MIBC) as a frother, hence meeting the required standard.  In addition, the total graphitic recovery of 84% was obtained as the maximum recovery. In light of the potential benefits of graphite in advancing industrialization, this study strongly recommends using froth flotation technology to upgrade the graphite ore from Chenjere to meet the global market specifications in terms of quality.