A CASE STUDY IN LIME
A TRADITIONAL KILN AT BOU NOURA, ALGERIA.
For developing countries the production of their own cementitious binders is of great
importance. The binders are essential components in all types of construction, but the cost of
some binders represents a very high expense for low-income communities. Countries which
need to import Portland cement lose valuable foreign exchange and the import of this cement
can make a significant contribution to the building up of a trade deficit.
In Algeria a positive development in recent years has been a large increase in the use of lime
in the building industry. This has been especially marked in the south of the country, which
represents 70 per cent of the area of the whole of Algeria.
In the Ghardaia region, which is located about 600 kms south of Algiers, traditional methods
of lime production are still used extensively. This case study describes an example of the
traditional technique for quicklime production. Specific details are given about a plant at
Bounoura, which is 10 kms from Ghardaia city.
Raw materials and quarrying techniques
The raw materials come from the Berriane-Metlili Hills situated close to the lime production
site. The deposits vary considerably in chemical composition between those with a relatively
low calcium carbonate content in Berriane and Metlili, where nevertheless two industrial lime
plants have been established, to those of almost pure calcium carbonate rocks at the
Quarrying at Bounoura is carried out by drilling, and also with picks and crowbars on the
surface. The stones are then broken down by hand using hammers. For the smaller size of
stones final crushing to the size required is often done in a hammer crusher. Once broken,
the stones are taken to the kiln site one kilometre away by a truck.
The kiln and firing method
There are three adjacent kilns on the lime production site at Bounoura. They can be fired
together but it is more usual to fire them separately. By firing the kilns in rotation it is
possible to economise slightly on the amount of fuel used because there is limited heat
transfer between the kiln being fired and an adjacent kiln.
The lime kiln is an adobe (mud block) construction. Stone walls surround the adobe to give
structural support. The kiln is of the funnel box type and is four metres high.
The diameter at the base is around three to four metres and two to three metres at the top.
The wall thickness is approximately 40 cm at the front and the sides.
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