Caracterização de minério de grafita de Almenara - MG

Abstract

Graphite is a mineral that finds application in a wide range of areas due to its unique characteristics, such as flexibility, chemical resistance, high electrical conductivity, and excellent refractory properties. Magnesita Refratários S.A. has conducted a mineral exploration project in order to evaluate the potential use of the graphite ore from Almenara (MG) deposit as raw material for refractories production. A study about the chemical, mineralogical and microstructural characteristics of five lithologies present in the deposit was carried out with the main objective of correlating these data with the response of the materials to the mineral concentration process. In addition to the usual characterization techniques, a method was developed for determining graphitic carbon content in graphite ore samples also. The results showed that the ores belonging to the G1 and G2 groups are predominantly comprised of schist graphite, in which the mineral is primarily associated to kaolinite and quartz. Carbon content and metallurgical recoveries in flotation are high to moderate. Samples from G3, G4 and G5 are mainly composed of gneiss graphite, but the nature of the mineral associations varies for these materials. Graphite in G3 samples is associated with quartz, feldspar and mica. Metallurgical recovery reached an intermediate level. In samples from G4 group, graphite occurs as fine particles and it has a strong association with mica and clay minerals, which reduces the metallurgical recoveries in flotation. The G5 samples contain graphite primarily associated with quartz, but the low carbon content in the ore makes its processing unattractive.