| |
|
The Quarry
The Quarry is situated to the Northeast of the plant. The principal limestone is nearly horizontal series of seams with a total thickness of 70 to 75 feet (21 to 23 m). The titration of the limestone is high, (about 90%) with a variation of a few percent. The limestone is drilled with ( 108 mm Ø holes ) and blasted. The yield is 7-10 Tons of limestone Kilogram explosive. The fragmentation is very good.
It is then loaded by shovels and loaders on 35-ton dumpers and dropped into the apron feeder of the crusher.
Limestone, Clay Crushing
Limestone and clay is crushed together by single stage double shaft 1200 t/h hammer crusher. Mixed material is fed to crusher by 2 apron feeders. Crushed material is transported to pre-blending yard by Arial Ropeway and belt conveyor.
Limestone and Clay Pre-blending Yard
Longitude pre-blending yard is adopted for pre-blending. There are 2 piles of material in the yard. Each pile can stock 35000t material. Stacker’s capacity is 1200t/h while re-claimer’s capacity is 600t/h. Mixed limestone and Clay are transported to the hopper of Dosing Station by belt conveyor.
Additive Crushing
Additives （high grade limestone, clay and iron ore） share one single stage hammer crusher with a capacity of 120t/h. Crushed material is transported to separate hoppers of Dosing Station by belt conveyor.
Raw Meal Dosing Station
In the Dosing Station, there are 4 hoppers used for mixing the materials, Raw mix, limestone, clay and iron ore. Apron feeders are installed at the bottom of clay hopper and iron ore hopper for discharging. Each material is discharged by weighing feeder according to certain proportion and transported to Raw Mill inlet by Belt Conveyor.
Raw Meal Grinding and Waste Gas Treatment
State of the art Loesche Vertical Roller mill is used for raw meal grinding. The capacity of Vertical Roller mill is 500t/h. Waste gas from kiln inlet is used for material drying. Waste gas is de dusted by E.P. before discharging into air. Dust from E.P., Conditioning Tower and cyclone to coal mill is transported to raw meal air slide by screw conveyor and bucket elevator. If the moisture of dust collected by Conditioning Tower is too high, the screw conveyor can run in opposite direction, thus the wet material is discharged from the other end. When the mill is shut down, waste gas will go through Conditioning Tower to lower the temperature to about 150c before entering E.P. Raw meal sampling equipment is installed before raw meal silo feeding bucket elevator. CCR can adjust the proportion of each material from weighing feeders to adjust the chemical composition of raw meal. A hot gas generator is installed for use during commissioning and while the kiln is stopped.
Raw Meal Silo
Raw Meal Silo is used for raw meal homogenizing. Capacity of raw meal silo is 18,000t. Raw meal is fed to the silo from raw mill by bucket elevator and air slide. Raw meal is discharged to raw meal measuring bin at silo bottom. Load cells are used for online calibration. Flow control valves and flow meters are installed at silo bottom for feed measurement. Weighed raw meal is fed to pre heater tower by air slide and bucket elevator.
Pyro System
Pyro System consists of Rotary Kiln, Double String 5 Stage Pre heater, TDF Pre calciner and Grate Cooler. The capacity of the Pyro System is 6700t/d. Tertiary air for pre calciner is taken out from Kiln hood and introduced to pre calciner by tertiary air duct. Third generation grate cooler is used for clinker cooling. Crushed clinker is transported to clinker storage by pan conveyor.
Clinker Storage
A 45,000t circular shed is used for clinker storage. Clinker is transported to Cement Mill Dosing Station by arc valve and belt conveyor. One small silo is used for un-burnt clinker.
Gypsum Crushing
Gypsum is fed to discharging pit by wheel loaders etc. Variable speed apron feeder will feed gypsum to crusher. Hammer Crusher is adopted for gypsum crushing. Crushed gypsum is fed to Cement Grinding Dosing Station by belt conveyor.
Cement Grinding Dosing Station
Two separate hoppers are used for clinker and gypsum with 2 x weighing feeders installed under each hopper to discharge material according to certain proportion and then to be transported to the cement mills. Optionally a third hopper for additive is also available.
Cement Grinding
Cement Grinding system includes 2 separate combined grinding systems. Each system consists of a roller press and ball mill, with capacity of 160t/h each. For each of the cement mill system, mixed material is transported from cement dosing station to V-type separator by belt conveyor and bucket elevator. Fine product from V-type separator goes to cyclone separator. Material collected by cyclone separator goes to ball mill and the remaining material with air goes to O-Sepa separator. Coarse product from V-type separator goes to intermediate hopper and then to the roller press. Pressed material from roller press goes together with the fresh material from dosing station to V-type separator. Material grinded by ball mill is conveyed by air slide and bucket elevator to O-Sepa separator. Coarse product from O-Sepa separator goes back to ball mill for regrinding while the fine product (cement) is collected by high efficiency bag filter. Cement is transported to cement silo by air slide and bucket elevator. Separate bag filter and fan is installed for cement mill air venting.
Cement Silo
Four 10,000 tons capacity silos are available for storing Cement received from the cement mills.
Packing Plant
Rotary packers with automatic truck loading machines are installed for efficient and swift dispatch of cement bags. Provision for dispatch of Bulk cement through bulk cement trucks is also available.
An extensive Railway wagon loading system is also installed for utilizing the country wide railway network.
Process Control
The process control and automation system comprise of operator workstations for the man-machine interface and programmable logic controllers (PLC’s) for motor control and alarm handling, loop control and process value acquisition. The latest DCS/ PLC system ensures that the product quality meets the international standards.
|
|
