4. UNIT OF MEASURE : CUBIC METRE (M3)
DENSITY : MIN 500 KG / M3 MAX 550 KG / M3
COMPRESSIVE STRENGTH : MIN 3.0 N / MM2 MAX 3.5 N /
MM2
I – BLOCKS
DIMENSIONS : Length – 625 mm
Width – 250 mm
Thickness – 75 mm, 100 mm, 125 mm, 150
mm,
200 mm and 250 mm.
II – RECLAIMED BLOCKS
DIMENSIONS : Length – 525 mm
Width – 250 mm
Thickness – 75 mm, 100 mm, 125 mm, 150
mm,
200 mm and 250 mm.
III- PACKING / TRANSPORTATION:
All these blocks are packed and loaded into trucks with the help of Forklift
trucks.
Loose packing can be tried out as per the requirement of marketing.
5. RAW MATERIAL
The main Raw Material used in manufacturing AAC Blocks are
1.Fly Ash
2.Cement
3.Lime
4.Gypsum
5.Water
The following material is also used for chemical reaction.
6.Alluminium CCC grade
7.Soluble Oil.
8.Caustic Soda.
Raw Materials Source:
Fly Ash is procured from nearby Thermal Power Stations in Trucks.
Cement is procured in bulkers.
Lime is procured in bags.
Gypsum is procured in bags.
Aluminium powder is procured in 30 kgs tins.
Soluble Oil is procured in 200 Ltrs. Drums.
Caustic Soda is procured from Local Market in 50 kg bags.
6. PROPERTIES OF RAW MATERIAL AND ITS ROLE IN PROCESS
1.FLY ASH:
Fly Ash is being received from different sources may have different grain size.
The surface area of the fly ash required is around 3000 blaine.
The flyash acts as aggregate.
2.CEMENT:
We need OPC 53 grade cement in our process.
Cement acts as a binder.
3.LIME:
Burnt lime in the process need to have a minimum slaking temperature of 55 °
centigrade.
The CaO content should be around 75%.
The lime also acts as binder and helps in chemical reaction when mixed with
Alluminium and water.
4.GYPSUM:
Gypsum acts as a setter in the product.
It helps in setting of raw material as per the required time.
5.ALUMINIUM POWDER:
Aluminium when mixed with lime generates hydrogen gas causing aeration.
The process is exothermic.
6.SOLUBLE OIL:
This material is used to control the rate of reaction.
7.CAUSTIC SODA:
This material is used as foaming agent for uniform mixing of Aluminum
powder.
7. STORAGE AND PREPARATION OF RAW MATERIAL
1.FLYASH:
Flyash is brought in form of pond-ash and stored in stock yard and mixed with
water in preperation tank to make slurry.The slurry thus made is transferred in
to slurry storage tanks.
The slurry is prepared in the Preperation tank keeping in mind the consistency
of the slurry. i.e. it should have about 65% consistency meaning in 1 kg of
slurry 650 grams of flyash is available.
Water is taken into the tank according to the quantity of the flyash unloaded.
The mixed slurry is checked for the spread before transferring to slurry tanks.
The spread of the slurry should be around 20 to 25 cms. This approximately
gives a consistency of 65% depending on the source and quality of the flyash
received.
2.CEMENT:
Cement is directly unloaded in to the silo through pneumatic conveying system.
3. LIME:
Lime is checked for slaking temperature before unloading into silo through
bucket elevator conveying system.
8. 4.GYPSUM:
Gypsum is stored at storage go-down.
5.ALUMINIUM:
Aluminium received in powder form in bulk of 30 kgs pack.The Aluminum
powder is stored in Aluminium go-down.
ALUMINUM IS HIGHLY INFLAMMABLE MATERIAL. NO WELDING / GAS
CUTTING IS TO BE DONE AND NO POWER TOOLS ETC SHOULD BE USED
IN THE VICINITY OF ALUMINUM TANKS AND LINES. NEVER USE VACUUM
CLEANER IN THE ALUMINUM AREA.WATER / FIRE SPARKS SHOULD NOT
FALL OVER ALUMINIUM AS IT WILL CAUSE FIRE.
6.SOLUBLE OIL:
Soluble Oil is used to control the rate of reaction.
Soluble Oil is received in 200 ltrs. drums.
7.CAUSTIC SODA:
Caustic Soda is received in 50 kgs bags.
9. TERMINOLOGY OF THE EQUIPEMENT IN PLANT & ITS USE
1.FLYASH SLURRY TANKS:
ST 1 & ST 2 – used for storing flyash slurry.
ST 3 – used for storing returns slurry.
2.PREPERATION TANK:
This tank is having spiral agitator mixes fly ash with water.
3.SCREW CONVEYORS:
Used for conveying raw material in dry form.
4.KNIFE GATES:
Flow of dry material into the screw conveyor can be controlled with Knife
gates. For any maintenance work on the screw conveyor, this gate has to
be closed to avoid material flowing out from the silo.
5.CEMENT SILO:
This is used for storing cement. We have one silo for storing cement
having a storage capacity of 90 MT.
6.LIME SILO:
This is used for storing Lime. We have one silo for storing Lime having a
storage capacity of 120 MT.
7.SLURRY BATCHER :
Flyash slurry and return slurry are taken in to this tank in measured
quantity.
10. 8.WATER BATCHER:
Water in measured quantity is taken into this tank.
9.CEMENT BATCHER :
Cement in measured quantity is taken in this tank.
10.LIME BATCHER :
Lime in measured quantity is taken in this tank.
11.MIXER:
Mixes the slurry material with dry raw material & aluminum and pours into
the mould
12.MOULD:
Used for transformation of poured slurry to the form of a cake.
13.TRANSFER CAR:
Used for transporting poured mould from pouring station to Parking area.
14.TILTING MACHINE:
Used for demoulding the cake from the mould & place the cake on cutting
trolley in vertical position.
15.CAKE TRANSPORT SYSTEM:
Used for transporting the cake over cutting trolley to long cutting station.
Used for transporting the cake over cutting trolley from long cutting station
to cross cutting station.
Used for transporting the cake over cutting trolley from cross cutting
station.
11. 16.LONG CUTTING MACHINE:
In this station, the side trimming with the help of vertical wires & the
length of the block with the help of blades is done in the cake. Later cutting
trolley moves forwards for cutting the thickness of the blocks with the help
of wires.
17.CROSS CUTTING SYSTEM:
In this station the Width of the block is cut with the help of wires.
18.LOADING MACHINE:
This machine shifts the green cake from the cutting trolley to autoclave
trolleys.
19.BOILER:
The coal fired boiler supplies steam to the autoclaves at 13 bar pressure
and 200° centigrade temperature.
20.AUTOCLAVES:
Used for curing the blocks with the help of steam.
21.WATER SOFTENING PLANT:
This plant supplies purified water to the boiler.
12. UTILITIES:
1.AIR COMPRESSORS:
Used for supplying compressed air for operating pneumatically operated
equipments.
2.DIESEL GENERATOR (DG) SET:
Captive power used during power failures.
3.FORKLIFT:
Used for shifting pallets from sagregation station to stock yard.
Used for loading trucks for dispatches.
13. PROCESS TERMS GENERALLY USED:
SPREAD/FLOW : A standard quantity of slurry material
measured on a smooth plate with a scale (spread/flow of the slurry).
CONSISTENCY : It is solids and water ratio of slurry
PENETRATION TEST : This is done to confirm whether the green
cake is cured for cutting. As we drop a rod 500 mm above from the top of
the cake, it will penetrate in to the cake. Penetration measurement shows
the hardness of the cake.
14. DIFFERENT STAGES OF PROCESS:
1.PREPARATION OF RECIPE:
Recipe is prepared based on the consistency/ density of Flyash slurry and
returns slurry.
2.CONSISTENCY TEST:
Take 1000 ml of slurry from the tank.
Take 30 grams of slurry.
Put it in the oven and dry the slurry at 100 deg Centigrade temperature for 1
hour.
Take out the material and weigh.
The dry weight divided by wet weight multiplied by 100 will give the weight of
the dry material in the slurry.
Eg. Wet weight is 30 grams
Dry weight is 12 grams
(12/30) x 100 = 40 i.e. 40% dry material is available indicating the consistency
as 40%.
3.SPREAD/FLOW TEST:
Fill up spread cone with 120 ml of slurry material.
Check the spread. Spread will vary according to the solid water ratio of the
slurry. Generally it should be around 20-24 cms.
15. 4.DENSITY TEST:
Take slurry in a container and weigh the same.
Take equal quantity of water in the same container and weigh the same.
Density = Weight / volume.
Divide slurry weight by water weight. This procedure is followed, as
water density is 1.
Example:
165gms of slurry divided by 100 gms of water = 165/100 = 1.65 g/cc.
16. RECIPE CALCULATIONS:
The total weight of the dry material is 1720 kgs approx. per batch. This is
shared
by the different raw materials as detailed below:
The raw material range of different material in dry form will as follows.
Dry qty in % age
Flyash - 950 kgs 53 to 57% }
} Aggregate
Returns - 270 kgs 14 to 18% }
Cement - 235kgs 12 to 16%
Lime - 240 kgs 12 to 16%
Gypsum - 25 kgs 1.3 to 1.8%
The figures give above are the standards. Recipe can vary within the
range keeping in mind the quality of the raw materials used.
17. CALCULATIONS OF WATER FROM SLURRY:
As return and fly ash slurry contains of about 45% and 35% respectively
indicating 55% consistency of returns and 65% consistency of fly ash , the
calculation of water is follows:
Returns : (270 X 100)/55 = 491 kgs of slurry.
Fly ash : (950 X 100)/65 = 1462 kgs of slurry.
From above the returns(cutting waste from green cake) is considered as fly
ash (aggregate). A minimum of 25% returns is used as aggregate per batch.
If the returns tank level is low the consumption can be reduced up to 22% of
the total aggregate (fly ash + returns).
Total weight of aggregate in dry form 270 + 950 = 1220 kgs.
% of returns slurry - (270 / 1220) X100 = 22% ,
% of fly ash slurry – (950 / 1220) X 100 = 78%
18. POURING:
Once the recipe is ready , the quantity (values) is to be fed in
computer for starting the pouring .
The first pour should always be taken in manual mode and from
second pour onwards auto cycle can be switched ‘ON’. This is a
must to avoid maloperation due to flag resetting at times.
CONDITIONS FOR STARTING THE MIXER:
Pre Measuring Tank, Batcher, Mixer should be in empty condition.
Load cell indicators should indicate – “Zero”.
Pre Measuring Tank , Mixer , Cement, Lime discharge valves should
be closed condition.
Mixer distributor should be cleaned.
19. OPERATING PANELS:
We have eight operating panels for plant operation. Each panel has
different screens
for operating the various sections of the concerned equipment. The
following are the panels.
1.Panel for fly ash mixing & slurry tank operations.
2.Panel for main mixer.
3.Panel for operating Transfer car 1.
4.Panel for tilting machine.
5.Panel for cutting trolley and cross cutting.
6.Panel for loading machine
7.Panel for winch systems.
8.Boiler has got a separate panel for its operation.
Some panels are PLC controlled ones.
20. CURING:
Our product is steam cured. Cut cakes are placed on a wagon (2 cakes on
one wagon), a train of 6 wagon, with 12 cakes are sent inside the Autoclave
for steam curing.
Cakes are cured inside the autoclave at 11-bar pressure and 200 degree
centigrade temperature.
After the train is loaded into the autoclave the following procedure of steam
feeding is to be done.
Vacuum - 0.5 hrs
Pressure increase up to reach 11 bar - 2.5 hrs
Curing at 11 bar - 7.0 hrs
Pressure release - 2.0 hrs
Loading and unloading are being done with the help of Winch drives.
Cured cakes are taken out for sagregation.
PRODUCT TESTING:
The cured block is tested for Density and Compressive Strength as per the
BIS procedure.
The Density of the block should be between 500 to 550 kg per M3 and
Compressive Strength should be a minimum of 3 N/mm2 to 3.5 N/mm2
21. START UP PROCEDURE:
Process Section:
Before starting the drive of any TANKS / SILOS, ensure the Tank / Silo is
clear of any debris, tools, plastic bags, ladder etc.
Ensure all pipe lines are connected properly.
Revoke work permit.
Restore power supply to the drives and START.
Ensure RPM of tank agitator is between 30 to 35 at full level.
If due to any reason the agitator drive is stopped for a longer period, ensure
that the material inside the tank is transferred to another tank. Do not leave
material inside the tank without agitator ON as the material will get set.
Cutting line and Wash water tanks agitator should always run whenever it
has material inside. If agitator stops pump out all the materials to avoid
jamming of tanks.
22. SHUT DOWN PROCEDURE
If any work is to be taken inside/on any slurry pit / any slurry tanks, ensure
no material is inside. Flush out suction and delivery lines to avoid
chocking.
Take work permit for taking up the maintenance work.
Complete the work in all respects. Take out tools, debris etc.
Take trials after completion of work.
Revoke safety permit and put the slurry pit / the slurry tank to use.
23. SAFETY PRECAUTIONS
During any cleaning / maintenance work ensure necessary safety gadgets
viz. hand gloves, safety glasses, nose masks, gumboots etc. are worn by
the workmen according to the need of the work.
Ensure safety work permit is obtained from the concerned department
before taking up the work.
During welding / gas cutting work nearer to the fire hazard places ensure
fire extinguishers / fire buckets with sand are readily available near the
work spot.
DONOT open / remove safety guards without safety permits.
24. SAFETY AT ALUMINUM WEIGHING / MIXING / STORING AREA:
Aluminum being highly inflammable material utmost care is to be taken to
avoid any fire hazard as detailed below:
Keep aluminum drums vertically.
Take only the required quantity of aluminum powder drums to the
Production area (not more than two drums at any given time).
Ensure all empty drums are shifted to empty drum storage area.
Avoid spillage of aluminum powder and clean the aluminum area (weighing
and mixing area) in every shift
25. REACTING ALUMINUM DRUMS:
In case any aluminum drum is found to be hot on touch, inform
shift in-charge immediately.
If it is an open drum, smother with sand to cut off air supply
caution must be taken on application of sand to aluminum as dust cloud
could be created. Remove drum to the safe area if possible.
If the drum is closed, remove to safe area provided the reaction is
not far advanced which is usually associated with the drum glowing and the
temperature of the drum increasing along with possible release of pressure.
In this circumstance allow reaction to subside naturally. DONOT REMOVE
the lid.
In all the above situations never switch ON or OFF any electrical
gadgets as spark may lignite the aluminum powder.
NO WELDING / GAS CUTTING IS ALLOWED NEAR ALUMINUM
STORAGE, MIXING, WEIGHING AREA
ALWAYS KEEP READY THE FIRE EXTINGUISHERS, SAND
BUCKETS ETC., NEAR ALUMINUM AREA.
NEVER DOUSE ALUMINUM FIRE WITH WATER, AS IT WILL FLARE UP.
SPRINKLE DRY FLYASH POWDER / GYPSUM / SAND OR USE
FIRE EXTINGUISHER ON ALUMINUM FIRE. THIS WILL CUT OFF OXYGEN
SUPPLY TO THE FIRE AND FIRE WILL GET EXTINGUISHED.
