A CASE STUDY IN
NO.2. IMPROVED TECHNIQUES AT CHENKUMBI, MALAWI.
4 TONNES PER DAY, MIXED FEED, FORCED AIR, VERTICAL SHAFT KILN
Lime has been used in the Malawian building industry for many generations, principally as
the cementing agent in renders and to produce a decorative whitewash.
In more recent years there has also been a demand for high quality lime from the sugar
processing industry and for soil stabilization in road construction.
The Chenkumbi Hills in central southern Malawi, 15 km south of the town of Balaka, is a
traditional lime producing area. It has grown in importance in the 1980s and 90s due to the
large deposits of calcitic marble of a reasonably high chemical purity.
Traditionally lime has been produced at Chenkumbi in large open box kilns (See Malawi lime
case study No 1). The techniques employed, however, were unable to meet the demand for
chemical grade lime required by the sugar processing industry, which had to import lime at
Figure 1: The improved kiln design.
This case study illustrates the results of
development work of Intermediate Technology
in collaboration with INDEFUND (a Malawian
lending bank promoting small industries) and
the local lime producers.
Raw materials and quarrying
The Chenkumbi Hills are formed by large
deposits of coarse grained, large crystalline
marble. The deposits vary considerably in
chemical content from almost pure calcium
carbonate to almost pure dolomite.
Only a small portion of the hills has been
geologically mapped in detail but in this
section alone measured reserves with a high
calcium carbonate content amount to 3.7
million tonnes. The Malawian Geological Survey
Department has trained the lime producers in a
simple acid reactivity test which helps select
the high quality deposits with a calcium
carbonate content (CaCO3) above 95%.
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