GEOLOGICAL, MINERAL AND PROCESS FEATURES OF FRIA BAUXITES (GUINEA)
Suss, A.G., Lukyanov, I.V., Panov, A.V. and Kopylov, A.V.
The Fria group of lateritic tropical bauxite deposits, located in Boke bauxite province, is a raw material base for Alumina Company of Guinea (ACG), the only alumina producer in the African continent. Estimated bauxite reserves at 6 major ore zones are about 600 million tonnes. Investigations of geological features of this group of deposits carried out in 60–70’s of 20th century by several organizations were not comprehensive enough.
The analysis of the region’s geology in light of contemporary knowledge of bauxite provinces of Guinea, obtained in the course of 40-years systematic studies by Russian geologists, has revealed several specific features of Fria bauxite.
Planned ACG expansion called for detailed studies of geological features of Fria bauxites as well as for repeated and more thorough study of their chemical and mineral composition and process properties in alumina production.
On the basis of many parameters, such as average content of available alumina and reactive silica, geological-technological mapping of Fria group was done that gave a new tool of resource estimation considering the bauxite nature specialties. As well it developed of ways of improving bauxite processing technology at ACG that have become a basis for the plant expansion.
Presence of finely dispersed boehmite in the initial bauxite stimulates the formation of secondary boehmite at the digestion stage under specific concentration modes. This particularity forces to limit the process parameters despite the process attractiveness of Fria bauxite processing at as low as possible caustic ratio in the liquid phase of digested slurry.