Page 16 - Leshobo Technical Report_October2016

3. ECONOMIC APPLICATIONS OF LIMESTONE

Limestone probably has the largest number of commercial applications of all the
industrial minerals, but the construction and cement manufacturers are the principal
consumers (Harrison, 1993). In construction, it is used as a source of lime to make cement,
as aggregate, rail ballast and dimension stone. It is used in the metallurgical industry
where large amounts of limestone are needed to remove impurities during the iron ore
and steel reduction (Agnello, 2005). Environmental and agricultural applications
include acidity neutralization (aglime), fine-gas desulphurisation; soil conditioning and
stabilization, fertilizing and animal feed (Mitchell, 2011). It is used as mineral filler in
paper, paint, plastic, rubber and pharmaceuticals. Crushed limestone is used in sewage
disposal plants for sewage purification. It is also used as an adhesive, abrasive, in glass
manufacturing and as a dietary supplement.

The presence of silica, alkalis and dolomite influences the grade of carbonate rocks.
Limestones with very high silica and dolomite content are considered low grade. The
grade of the limestone is the one that determines its uses. Limestones are classified into;
construction aggregates, cement, lime, chemical reagent, medium value powders, and
high value powders with the purity of the limestone increasing respectively (Harrison, et
al., 1992). Shown in Table 1.1 is the classification of limestone based on the CaO
content.

Category Percentage CaCO3 Percentage CaO
Very high purity > 98.5 > 55.2
High purity 97.0 - 98.5 54.3 - 55.2
Medium purity 93.5 - 97.0 52.4 - 54.3
Low purity 85.0 - 93.5 47.6 - 52.4
impure < 85.0 < 47.6

Table 3.1: Classification of limestone on the percentage of CaCO3 (Cox et al., 1977)

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