Page 33 - Leshobo Technical Report_October2016

Technical Report for the

LESHOBO LIMESTONE

Taung, North-West Province

6. ANALYSIS AND INTERPRETATION

Limestones are composed almost entirely of calcite (CaCO3) but usually contain other
minerals such as dolomite (CaMg (CO3)2), silica (SiO2), alkalis (Na, Mg, K), Iron oxides
(Fe2O3), aluminium oxides (Al2O3), and organic materials (containing C). From the
tested samples, CaCO3 content ranges between 85.16 % and 95.78 % (Fig 8.1) and
all are above the cut-off grade of 85%.

Dolomite composition in limestone is indicated by the MgO content, but this can also
be partially assigned to the alkalis present. Dolomite is considered harmful if present in
amounts greater than a few percent. From the tested samples, MgO content ranges
between 1.06 % and 2.73 % (Fig. 8.2). Higher MgO content is correlated to lower
CaCO3 and vice versa. The MgO content is also within the tolerable amount.
Silica dilutes the purity of a limestone and is considered harmful to the limestone if
present in significant quantities. SiO2 (Fig 8.3) is directly proportional to MgO and it
shows the same behaviour as MgO relative to CaCO3. Alkalis (Na, K) are confined in
the silica and are present in quantities less than 0.2 %. Mg is not included in the total
alkalis as the Mg as an alkali content cannot be distinguished from the Mg in the
dolomite.

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