Cover Image
close this book Small Scale Production of Lime for Building
close this folder 1. General Information
View the document 1.1 Geological description of limestone
View the document 1.2 Chemical composition of limestone
View the document 1.3 Physical characteristics of limestone
View the document 1.4 Classification of limestone
View the document 1.5 Chemical reactions in the production of lime
View the document 1.6 Common uses of lime in developing countries

1.2 Chemical composition of limestone

Limestone is made up of varying proportions of the following chemicals with calcium and magnesium carbonate being the two major components.

Calcium carbonate

CaCO3

Magnesium carbonate

MgCO3

Silica

SiO2

Alumina

Al2O3

Iron oxide

Fe2O3

Sulphate

SO3

Phosphorus

P2O5

Potash

K2O

Soda

Na2O

The two main impurities are silica and alumina with iron as the third.

For a general purpose lime, a limestone with an SiO2 content of up to 3.5 % and Al2O3 content of up to 2.5 % may be used where purer stone is not available, whereas lime for building or road construction purposes may have an SiO2 content of up to 10% (perhaps slightly more) and an Al2O3 content of 5 %. An Al2O3 proportion of greater than 5% will produce a semi-hydraulic or hydraulic lime.