Introduction of Bhaktapur Itta Tatha Tile Udyog (P) Ltd
The Bhaktapur brick factory was registered in 1975 under the company act 1964 with the objective of accelerating the developing of the country by providing the machine made high quality for private and public sector construction. The company was established with financial and technical assistance from people‘s Republic of China and commenced the production in 1979.The land coverage area of the factory is 248 ropany. The production capacity is approximately 15 million per annum The design, production process and equipment are all Chinese origin. The Bhaktapur Brick factory limited was privatized on 15 January 2004 under the Nepal government privatization act and since then it has been running as Bhaktapur Itta Tatha Tile Udhyog (Pvt) Ltd with the objective of
- 1. To smoothen the production and supply of machine made of BTTF by improving the management.
- 2. To improve quality and quantity of product of BTTF by injecting more capital and advanced technologies (including foreign capital and technological investment).
- 3. To generate real employment opportunity in the long run by promoting production and sales.
The BTTF has been running for eight and half year with the employee of about 250 direct labors and 50 indirect labors. And other public has been benefitting from this industry such as of transporter businessman, restaurants and loaders. The plant consists of two units of extruded brick making machine rated capacity of 10000 units per hour and two units of 22 chambers Hoffman kiln with the baking capacity of 40000 units of red brick each per day. Most of the original facilities and equipment are still use. It has access to a source of clay of required quality, it need minimum preparation and processing before using final product. Generally The BBTF has been producing machine made fired clay brick. Machine made brick: These are of high strength, clear surface and suitable for fair face brick construction. These are very popular of high class housing, hotels and commercial complex. The process carried out for making bricks are
- 1. Unsoiling: About 20 cm of top layer of the earth normally containing stones, pebbles, gravel and roots are removed.
- 2. Digging: The soil is evacuated with the help of excavator and dragline. The soil mass is peddled and left for weathering and subsequent processing. The digging operation should be done before rain.
- 3. Weathering: The soiled is heaped on the ground in layer of 7 meter. The soil is exposed of the soil if they are from the different source and also remove the impurities which get oxidized. BY weathering the plasticity of the clay is improved.
- 4. Blending: Then the seasoning clay is transported to the brick shop for blending. Moderate amount of water is added so as to obtain the right consistency for moulding. The mass send through roller and double mixer to get good plasticity and workability.
- 5. Tempering: again the mass of clay is mixed in double shaft mixer to get stiff more plasticity.
- 6. Moulding: The stiffer clay is forced through a rectangular opening die of brick size by means of auger. Clay comes out from the die in the form of bar. The brick are cut from the bar with the cutting machine of consisting of several steel wire.
- 7. Drying: Green brick contain about 14 percent moister. The object of drying is to remove moisture to control shrinkage and save fuel and burning time. The drying shrinkage depends upon pore spaces within the clay and mixing water. The addition of sand of ground burnt clay reduces shrinkage, increase porosity and help on quick drying. The moister contain is brought down to 3 % under exposed condition within two weeks. Thus the strength of the green bricks is increased and the brick can be handled safely.
- 8. Burning: The burning is done in Hoffman kiln also known as continuous kiln. Here the kiln has 22 chambers and each chamber has 9000 brick baking capacity. In this kiln the brick are stacked in the various chambers wherein the bricks undergo different treatment at the same time. When the bricks in one chamber are forced, the bricks in the next set of chamber are dried and preheated while bricks in the order set of chamber are loaded and in the last are cooled.
The burning of clay is divided in three main stages
- 1. Dehydration: This is known as water smoking stage. During dehydration water is dried and clay loses the plasticity. This take place at the temperature of 400 deg C to 650 deg C.
- 2. Oxidation Period: During oxidation period the remaining carbon is eliminated and ferrous iron is oxidized to ferric form. The oxidation takes place at the temperature between 650 deg C to 900 Deg C.
- 3. Verification: To convert the mass into glass like substances. The temperature ranges 900 deg C to 1000 deg C. the cure should be taken for preventing the cracking at this stage.