IGLOO TYPE BRICK
KILNS
IN ZIMBABWE
Introduction
Igloo or beehive kilns (as they are
generally known in Zimbabwe)
derive their name from the shape
of the kiln. In the majority of
cases, igloo kilns in Zimbabwe are
used for firing refractory, face,
industrial bricks, pavers, window
sills, glazed earthenware sewer
pipes, and, in some cases, pottery.
However, this document focusses
on the use of igloo kilns
specifically in brick production and
is based on the study of three
different production plants.
The major source of energy used
for firing bricks in igloo/beehive
kilns in Zimbabwe is coal, and the
coal is manually fed in the majority Figure 1: View of an igloo (or beehive) kiln and chimney
of cases. The coal used is generally
in the form of large pieces averaging about 120 mm in diameter. The size of coal is referred to
as "rounds" in the brick production industry and these pieces glow or burn for a relatively long
duration.
Generic classification of igloo kilns, according to the mode of operation
An igloo/beehive kiln is essentially an intermittent down-draught kiln, where heat from the fire
boxes in the form of a "heat wave" is deflected upwards by buffer walls to the roof of the dome
shaped kiln and drawn down through the brick setting by means of a chimney away via the
perforated floor, side flue channels, and the main flue duct. There is no direct contact between
the fuel and the bricks.
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