ppc riebeeck mine and cement factory - Aurecon AME ...

PPC Riebeeck West: Storm water Management Plan Page 35
Kiln exhaust gas is used to assist in the drying of the coal. The coal milling circuit is equipped
with a process bag filter to collect the milled coal and to clean the hot gas used to dry the coal
during milling.
1.9.5 Burning
Figure 1.19: Burning
Preheater, Kiln and Cooler
Raw meal extracted from the homogenising silo via a weighing system, combined with the dust
return from the main kiln/raw mill dust bag filter, is fed to the six-stage cyclone pre-heater
system, with a low NOx in-line calciner (ILC), by means of chain bucket elevators. The feed
system allows for feeding the raw meal into the sixth or fifth cyclone stages. The precalcined
material is fed into one end of the kiln, and pulverised coal is burnt at the other end. The raw
meal slowly cascades down the inclined kiln towards the heat and reaches a temperature of
about 1 450 °C in the burning zone where a process called clinkering occurs. The pre-heater is
about 130m tall, the tallest structure on the site, and makes use of hot air from the kiln to warm
up the raw meal to improve energy efficiency.
The clinker exits the kiln into a grate-type cooler fitted with a triple - roll crusher. The grate
cooler is sized to match kiln production including kiln flushes. Tertiary air may be drawn from the
kiln hood and / or the clinker cooler. Excess air from the grate cooler is passed through a heat
exchanger before being vented to the atmosphere through a bag filter.
The clinker is sampled by means of an automated sampling station located at the discharge
chute of the kiln feeding the clinker cooler. The samples are pneumatically conveyed to the
laboratory for analysis, the results of which are used for quality control of the clinker production
process.