Abstract
Glen Douglas Dolomite Mine, an operation located south of Johannesburg in the Vaal area is faced with a challenge of running out of metallurgical dolomite (i.e., principally the low silica Lyttelton Formation), which is the core commodity of the mine. The distribution of lithological units of the Malmani Subgroup at Glen Douglas Dolomite Mine are not clearly understood.
In order to understand the distribution of the lithological units of the Malmani Subgroup, a study of the lithofacies was conducted at Glen Douglas Dolomite Mine. This helped identify the different formations of the Malmani Subgroup. The stratigraphic and geochemical variation of the dolomite units is influenced by younger intrusions occurring in the pit.
Lithofacies of the Malmani Subgroup at Glen Douglas Dolomite Mine were documented, but this was limited by accessibility to the pit benches. Some areas were easily accessible, and some were not accessible at all. Based on this, there is little lithological grounds for the identification of the Monte Christo and Eccles Formations at Glen Douglas Dolomite Mine. All units encountered at Glen Douglas Dolomite Mine conform to descriptions of the Lyttelton Formation, but they exhibit varying Silica-content. The lithofacies and geochemical data have to a large degree shown the prominence of the Lyttelton Formation to be on the western side of both B and C-pit, with little SiO2 contamination existing as a result of mafic intrusions, detrital inputs or chertification.
Old borehole data obtained from the mine were utilised to create a geological block model. The block model was constructed based on SiO2 values and shows very healthy reserves for both metallurgical and aggregate dolomite. It can be deduced that the uppermost part of the Monte Christo Formation only intersects the pit area on the lowermost part of the eastern bench profile.