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Image by Bernard Hermant


(Appropriate for Gujarat)

Note: This Project Profile should be used as a general guideline only and it may be modified by incorporating the actual input costs and prevalent manufacturing practice at a particular location.

1.0  Details of manufacturing process to be adopted:


a. Clay winning (or excavation) Clay winning (or excavation) is done by using a JCB and care is taken to avoid calcareous clay or clay containing lime nodules. Clay is dug vertically from top to bottom of the exposed face so that material in all intermediate strata gets mixed in the process. The excavated clay is transported in trucks or tractor trolleys to the plant. Clay, stone dust and rice husk are stocked in separate heaps at the plant. They are then taken in the desired proportion by using JCB buckets and carried to the mixing floor. These materials are first dry-mixed by using JCB and then sprinkled with water and kneaded by using a Rotavator fitted to a Tractor. This raw-mix is then kept soaked in water for at least a week to improve its homogeneity.


b. Shaping:

The soaked raw-mix is then fed to Hopper of the Box Feeder by using JCB. The raw-mix falls on to the belt conveyor fitted below the Box Feeder and is carried to Roller Crusher-Cum-Stone Separator.  Its output is carried to Hopper of ‘Ishtika’ Mixerpress (IMP) by another belt conveyor. The IMP consists of a mixer, a press block, a mould chain, a scraper belt, a mould washing station and a mould sander.  Final adjustment of water content in the raw-mix can be done by adding 5 to 7 % water in the mixer.  The Ishtika Mixerpress requires about 90.20 KW (121 HP) connected load.  8 bricks are shaped every stroke on a metal pallet. The mixerpress operates at a speed of up to 15 strokes per minute. Thus, capacity of the Ishtika Mixerpress is 7,200 bricks (of 230 x 110 x 70 mm fired size) per hour.

c.  Drying:


Loaded pallets coming out of the Ishtika Mixerpress on its Chain Conveyor are then transferred manually to battery-operated cars which are carried to open Drying Yard.  Pallets are unloaded manually from the battery-operated cars and placed on waste fired bricks set on edge and kept in regular rows on open ground. This ensures at least a few inches air gap below the pallets for air circulation.   

After 2 days, bricks are manually turned on their edges for faster drying.  Bricks dry in this position for another 2 days.  They are then arranged on metal pallets in stacks and kept till such time they become ‘reasonably’ dry (i.e. till their moisture content is reduced from about 27 per cent to below 7 per cent).  These dry brick stacks are then carried by forklift inside the setting area of HD/Natural Zigzag Kiln through its wickets (or doors). 

d. Firing:

Dry bricks are manually set in a pre-determined pattern with trace holes, fuel shafts, flues, etc. kept in accordance with set practice.  Natural Draught Zigzag Kiln is a continuous kiln working on draught created by an ID Fan or Chimney.  Crushed lignite is used as the main fuel for firing bricks.  Wood/saw dust may be used as additional fuel.  Fuel is fed through feed holes provided in the kiln-top.  Firing temperature ranges between 9500 C and 10500 C.  Fully fired and cooled bricks are manually unloaded and carried to the Open Brick Yard or are directly loaded into trucks and dispatched.  

  1. Unlike ‘hand-moulding’ operation, soft mud machine moulding provides much better occupational health and safety conditions to workers.  It also reduces labour intensity of the traditional shaping and drying operations by a factor of 8 and eliminates dependence on skilled ‘moulders’ by delinking quality of green bricks from human skill levels. 

  2. Machine-moulded bricks are uniform in size and shape and have perpendicular faces and sharp edges.  Therefore, use of these bricks in walling saves up to 15 % mortar and plastering expenses.

  3. Thorough mixing of raw-mix components in the mixer results into uniform firing, better crushing strength and lower breakages during handling. 

  4. Unlike extruder, the mixerpress exerts only the bare minimum pressure required for proper shaping of green bricks thereby ensuring a reasonably ‘open’ brick body which can be directly dried under the sun without fear of cracking.  Also, soft mud machine molding can have frogs of any size and detail which extruded bricks cannot have and which are always preferred by the market.

  5. Soft mud machine moulding process can incorporate much higher percentage of 'non-plastic' wastes, fuels and / or soils as compared to extrusion.   The wastes could be from agriculture, urban waste treatment plants and industries like coal processing, textile, tanning, sugar, liquor, petroleum, paper, wood-processing, agro / food processing, etc.

    This solves the disposal problem of the waste generating agencies; minimizes the requirement of primarily extracted clays and fossil fuels; increases the porosity of fired bricks making them lightweight and thermally / acoustically more insulating and improves the enterprise profitability by saving costly external fuel, which forms 25- 40 % of cost of production of bricks.  Lightweight bricks also require less transportation energy and can be handled easily by laborers thereby improving their comfort level and speed of work.   

  6. Ishtika Mixerpress is an ideal machine for manufacturing terrace tiles and pavers with chamfered edges. Chamfering is made possible in the soft mud molding process by making special provision in each mould cavity. Chamfering operation is very difficult in the extrusion process.Terrace tiles and pavers add much better value than ordinary fired clay bricks.

2.0 Advantages of the soft mud moulding process:

It is assumed that the promoter owns at least 5 acres of land (10 acres is more appropriate considering future expansion/mechanization) for the project on which he already has an operating HD/Natural Zigzag Kiln of around 35,000 bricks / day capacity (including appropriate facilities for water pumping / storage and coal crushing).  Therefore, these costs have not been included in the Project Cost.           

3.0 Project Feasibility:

3.1 Production:

Green bricks moulded / hour = 8 bricks / stroke x 15 strokes / minute x 60 minutes / hour = 7,200 nos.

Assuming about 70 % working efficiency of the plant, green bricks moulded / shift / day = 7,200 x 8 x 0.70 = 40,000 nos. 

b)  Assuming 2 % production loss during drying and 1 % during firing; 245 firing days / season (i.e. 35 weeks x 7 days / year) and 210 moulding days / season (i.e. 35 weeks x 6 days / year),
Green bricks moulded / season = 40,000 x 210 = 84,00,000 Production of saleable fired bricks / season = 84,00,000 x 0.98 x 0.99 ≈ 81,50,000 nos.      

Production of saleable fired bricks / day = 81,50,000 / 245  ≈ 33,000 nos.            

3.2  Estimated Additional Investment:

3.3 Cost of production @ 100% capacity utilization (i.e. @ 81,50,000  bricks / year or 33,000 bricks / day):   

* 7 KW Box Feeder + 4.40 KW Conveyor + 18.50 KW Roller Crusher-Cum-Stone Separator + 90.20 KW Ishtika Mixerpress + 7.50 KW Coal Crusher + 3.75 KW 
            Raw Water Pump

Minimum selling price expected (ex-kiln) = Rs. 6,000/- per 1,000 bricks

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