chapter - 1 introduction - Meghalaya State Pollution Control Board

Hills Cement Co. Limited.
Capacity and Type of Main Storages
SL NO Material
Capacity Tons Type
01 Crushed
Limestone
3x12,000 Rectangular in-line
pre-blending stockpile
02 Clay 7,600 Storage Yard
03 Sand stone 4,700 Storage Yard
04 Gypsum 3,000 Covered Storage
05 Calcined Clay 1,500 Covered Storage
06 Clinker 23,500 RCC Silo
07 Cement 18,000 Stock Pile
08 Coal 7,000 Covered Storage
2. Dry grinding processing
The materials are ground into a flow able powder in horizontal ball mills or
in vertical roller mills. Utilizing waste heat from the kiln exhaust, clinker
cooler hood, or auxiliary heat from a standalone air heater before
pyroprocessing may further dry the raw materials. The moisture content in
the kiln feed of the dry kiln is typically around 0.5% (0 - 0.7%). In a dry
rotary kiln, feed material with much lower moisture content (0.5%) is
used, thereby reducing the need for evaporation and reducing kiln length.
3. Clinker Production
Clinker production is the most energy-intensive stage in cement
production, accounting for over 90% of total industry energy use, and
virtually all of the fuel use. Clinker is produced by pyroprocessing in large
kilns. While many different fuels can be used in the kiln, coal has been
used as the primary fuel.
Alkali or kiln dust (KD) bypass systems may be required in kilns to
remove alkalis, sulfates, and/or chlorides. Such systems lead to additional
energy losses since sensible heat is removed with the bypass gas and
dust. Once the clinker is formed in the rotary kiln, it is cooled rapidly to
minimize the formation of a glass phase and ensure the maximum yield.
The main cooling technologies are either the grate cooler or the tube or
planetary cooler. In the grate cooler, the clinker is transported over a
reciprocating grate. Air flows perpendicular to the flow of clinker.
Pollution Control Consultants (India) Pvt. Ltd. 19