CITIC IC developed large new dry process cement rotary kiln product
with cement research and design institutes in Tianjin, Nanjing and
Hefei by using domestic advanced technology, and the product can
match 3000～10000t/d large new dry process cement production line.
The company has a first-rate rotary kiln development, research and
design team, perfect test and inspection means and excellent large
rotary kiln manufacturing equipment and manufacturing technology,
and has formed a complete technology and production system
integrating rotary kiln design, manufacture, install and debugging
Cement Rotary Kiln
Rotary Kiln Processes
With the arrival of rotary kilns, cement manufacturing processes
became sharply defined according to the form in which the raw
materials are fed to the kiln. Raw materials were either ground
with addition of water, to form a slurry containing typically
30-45% water, or they were ground dry, to form a powder or "raw
- In the Wet Process, the kiln system is fed with liquid slurry, the water then being
evaporated in the kiln.
- In the Semi-Wet Process, raw material is prepared as a slurry, but a substantial
proportion (50-80%) of the water is mechanically removed, usually
by filtration, and the resulting "filter cake" is fed to the kiln
- In the Dry Process, the kiln system is fed with dry raw meal powder.
- In the Semi-Dry Process, a limited amount of water (10-15%) is added to dry raw meal so
that it can be nodulised, and the damp nodules are fed to the kiln
CITICIC Cement rotary kiln technical characteristics：
Kiln body is made of high quality composed of carbon steel or alloy
steel plate and automatic welding;
Tyre、Support Roller、Open gear adopts alloy cast steel
Sliding bearing with large gap not scraping tile bearing;
Transmission device adopts hard tooth surface reducer, flexible
diaphragm coupling, dc motor;
Adopts hydraulic gear wheel;
Preheater scales were used respectively to veiw of kiln head, and
cylinder pressure tight seal;
A slow drive device.
Wet process kilns
The original rotary cement kilns were called 'wet process' kilns.
In their basic form they were relatively simple compared with
modern developments. The raw meal was supplied at ambient
temperature in the form of a slurry.
A wet process kiln may be up to 200m long and 6m in diameter.It has
to be long because a lot of water has to be evaporated and the
process of heat transfer is not very efficient.
The slurry may contain about 40% water. This takes a lot of energy
to evaporate and various developments of the wet process were aimed
at reducing the water content of the raw meal. An example of this
is the 'filter press' (imagine a musical accordion 10-20 metres
long and several metres across) - such adaptions were described as
The wet process has survived for over a century because many raw
materials are suited to blending as a slurry. Also, for many years,
it was technically difficult to get dry powders to blend
Quite a few wet process kilns are still in operation, usually now
with higher-tech bits bolted on. However, new cement kilns are of
the 'dry process' type.
Dry process kilns
In a modern works, the blended raw material enters the kiln via the
pre-heater tower. Here, hot gases from the kiln, and probably the
cooled clinker at the far end of the kiln, are used to heat the raw
meal. As a result, the raw meal is already hot before it enters the
The dry process is much more thermally efficient than the wet
Firstly, and most obviously, this is because the meal is a dry
powder and there is little or no water that has to be evaporated.
Secondly, and less obviously, the process of transferring heat is
much more efficient in a dry process kiln.
An integral part of the process is a heat exchanger called a
'suspension preheater'. This is a tower with a series of cyclones
in which fast-moving hot gases keep the meal powder suspended in
air. All the time, the meal gets hotter and the gas gets cooler
until the meal is at almost the same temperature as the gas.
The basic dry process system consists of the kiln and a suspension
preheater. The raw materials, limestone and shale for example, are
ground finely and blended to produce the raw meal. The raw meal is
fed in at the top of the preheater tower and passes through t