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VERTICAL SHAFT BRICK KLIN TECHNOLOGY
Energy efficient Environmentally sound Economically viable
VSBK – 11, Hemant Prajapati, Guna
VSBK - 12, Hemant Prajapati, Guna VSBK 12 is located on the Guna – Ashoknagar highway approximately 18 kms from Guna on the banks of Sindh river. A perspective view of the kiln can also be had, traveling on the Guna – Bina broad gauge railway line. Layout of the kiln started on 10th. December, 2001 and construction including ramp was over by 5th. of January, 2002 in a record time of 26 days.

Previously most of the construction work used to be completed within a time frame of 45 days. However in VSBK – 12, faster construction was possible mainly due to:

  1. Timely available of construction materials
  2. Higher engagement of work force i.e. masons and labours
  3. Dedication and ownership responsibility in work of workers
  4. Enthusiasm and keenness of entrepreneur in the work being carried out
  5. Able supervision

Guna kiln has been constructed at a 12 batch height due to excellent quality of green bricks with 2 shafts of nominal size 1m x 2m. In and around Guna, raw material (soil) is processed by filtration technique akin to ceramic processing, locally coined as GHOL process. This is necessary to separate the morum particles contained in the soil. 

The process also ensures adequate plasticity of the soil, proper ageing and uniform mixing with added internal fuel and anti-shrinkage materials. Although the method observed was quite crude from the technological aspect but was found to be extremely effective to produce good quality bricks from inferior quality soil. VSBK - 12, Hemant Prajapati, Guna

Soil for brick making is presently excavated from site only. Due to highly undulating nature of the topography, on an average 8 to 10 ft of soil can be taken out for brick making. Enough soil is available to last for a couple of years. Entrepreneur has also thought of soil transportation to site in future. The excavated soil is transported by donkeys to a rectangular vat. Water is fed into the vat and the soil-water mixture is agitated by a blunger. After the soil is deflocculated and mixed intimately with the water the resultant slurry is passed through a 2mm sieve. Residues in the form of morum, stone particles are rejected. The slurry is gravitationally transported through channels to storage tanks of 10ft x 5ft dimension and depth of 3ft. After allowing a settling time of 24 hours the water is decanted off by pump and manually also. Wheat straw is added to this slurry about 2 – 4% by weight and left to age for 4 days. During this time besides ageing, extra moisture in the filtrated soil evaporates, making it amenable for shaping by jand moulding. After 4 days, internal fuel in the form of cinder ash is mixed about 6 – 10% by weight alongwith filler anti-shrinkage stone dust in the quantity of 8 – 12% by weight. Addition of stone dust helps in arresting the high shrinkage, besides increasing the fired density and physico-mechanical properties due to greater specific gravity compared to soil. After the required external material addition, the soil is mixed in the tank manually and left to age for another 2 days. The entire process is over by around 7 days whence the mixture is ready for shaping into green bricks.

VSBK - 12, Hemant Prajapati, Guna
Soil excavated from site or transported
Transported by donkeys


VSBK - 12, Hemant Prajapati, Guna
Mix with water and agitated in vat by blunger
20 HP motor




VSBK - 12, Hemant Prajapati, Guna
Filtration to separate > 2mm particles


VSBK - 12, Hemant Prajapati, Guna
Gravity transportation to earthen tank
 
Through gravity drains


Decantation of water by pump and manually
Wheat straw mixed to 2-4% by weight
Measured by basket, manual mixing

Mixed Coal ash 6-10%Stone dust 8-12%

Measured by basket, manual mixing
Manual mixing
Mixed by foot, transportation by cart
Moulding to green bricks
VSBK - 12, Hemant Prajapati, Guna
VSBK - 12, Hemant Prajapati, Guna
Initially the green bricks were being demoulded from moulds by using fine coal dust. This not only increased the cost, but also produced inferior surface colour bricks. Entrepreneur was convinced to change the demoulding material from coal dust to parting sand. This not only drastically changed the colour of the fired bricks but also gave a better surface finish when fired in VSBK. The shapes of the frog in his bricks were changed from tetragonal to elliptical in shape along with the lettering PRAJA from Hindi to English. Depth of the frog was increased by 2mm. This will entail savings on soil thus increasing profitability. Change in frog lettering although has technological importance but provides a meaningful social implication. It not only helps in distinguishing his bricks from the nearby clamps but also enhances his image among the generally illiterate – semi illiterate belt with the English monogram. Size of mould was also changed to increase the size of the fired bricks. Previously his burnt brick size was 8.75 in. x 4 in. x 2.25 in. which was increased to 9 in. x 4.25 in. x 2.75 in. This size is more acceptable in local conditions and also stands out when compared to the local bricks being produced.
VSBK - 12, Hemant Prajapati, Guna Although construction was completed on 5th. January, 2002, firing in first shaft commenced on 10th. February, 2002. This delay of more than a month was due to non-availability of trolley and screw jack. Kiln equipments were supplied by Mr. Narayan Das Prajapati and the inadvertent delay was caused from his end only. During this time entrepreneur was appraised of the pros and cons of equipment supply by an in experienced fabricator. 

Upon inspection of the equipments, they were found to be of improper quality and specifications. 
To reduce the cost materials used were not of required grade along with poor welding quality. Entrepreneur was shown the problems and appraised of the future problems on working with these materials.

Shaft I was initialized on 10th. February, 2002. Initially the shaft was loaded in double chulha pattern containing 80 + 64 + 80 + 64 total of 288 bricks along with 20 kg of external fuel. Firing was started from the bottom. New pattern of loading during firing initialization has been followed from this season in all the newly and also old kilns. This type of loading increases the airflow thus helping in faster travel of fire. This results is faster stabilization. After initial start with 12 batches in double chulha pattern the old Datia pattern was reverted to. This increased the quantity of bricks loaded from 288 to 346. Coal quantity after the first 24 hours of firing was gradually reduced to 12 kg per batch which amounts to 3.5 tonnes per lakh. After about 10 days of stabilization coal quantity was further reduced to 9 kg per batch amounting to 2.5 tonnes per lakh. At present external fuel consumption is around 1 tonnes per lakh. Previously in clamp coal consumption was around 2.5 tonnes per lakh. Thus VSBK firing has a saving of around 60% of external fuel compared to clamps. In VSBK firing on shaft I breakage is on an average 6 bricks per batch equivalent to 1 % which is worth mentioning compared to 4% breakage in clamps. Good quality of green bricks of high green strength reduces the breakage. Shaft II was fired on 4th. March, 2002 and was also stabilized after 2 days. Breakage quantity and fuel consumption is also similar to shaft I.

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