Two types of boiler ash are being produced fine dust and relatively coarse granules of less than 1mm. The total quantity being produced is approximately 210 MT per month with a ratio of 9:1 for fine and coarse.

The primary objectives of the study were as follows:

n  To suggest possibilities of a continuous supply at Datia.

n  Economic feasibility of replacing brick making with sponge iron waste.

Both the types of samples, i.e., powder and granular boiler ash waste were collected from BHEL. For energy calculations, the samples were tested for calorific value (CV) and ash content. To compare the data with presently used sponge iron waste from Bilaspur, its CV was again determined. Depending upon the heat value of the waste material, various compositions were made, completely replacing sponge iron waste. The soil used was similar to the one used for normal brick production at Datia.

Compositions were hand moulded, properly dried and fired in a VSBK in order to simulate actual conditions of firing and then compared with the presently used bricks. Fired samples were subjected to physical and destructive tests in order to determine the usable properties.

Results of calorific value tests are as under:

1.  Coal being used as on 15 February 2007           3517 KCal/kg

2.  Sponge iron waste as on 15 February 2007       2581 KCal/kg

3.  Boiler ash from BHEL (powder)                        1030 KCal/kg

4.  Boiler ash from BHEL (granular)                       1217 KCal/kg

For calculating the total energy requirement for a good quality fired brick in a VSBK, it is an established norm to add 5% by weight sponge iron waste. This is also based on the profitability and optimum quality of the fired brick. Thus, various compositions were made to establish the optimum quality.

The best compressive strength was achieved with 10% addition of boiler ash. However, calculating the total energy supplied in the form of internal fuel, an addition of 12%-14% BHEL boiler ash will be economically feasible without compromising the strength.

[Amount of energy from internal fuel as sponge iron waste, considering a brick weight of 3 kg =

3 x 0.05 x 2581 x 1000 = 387150 KCal/1000 bricks)

Amount of BHEL boiler ash in powder form, required to get equivalent amount of energy as sponge iron waste = 387150/1030 kg/1000 bricks = 375 kg/1000 bricks = 13% by weight]

At present, 5% by weight of sponge iron waste is being used in hand-moulded bricks at Rs. 1500 per tonne, including transportation from Bilaspur.Thus, the total expenses of internal fuel (sponge iron waste) = Rs. 225 per 1000 bricks

Amount of BHEL boiler ash to be mixed considering the equivalent energy content as sponge iron waste and taking into consideration the cost of transportation and storage waste due to fineness of the material = 400 kg per 1000 bricks

Thus, equivalent cost of BHEL boiler ash compared to presently used sponge iron waste inclusive of transportation costs =

Rs.225/400 = Rs. 562 per ton.

Based on the test results and the above energy calculations, it has been recommended to EcoKiln units in and around Bharat Heavy Electricals, Jhansi to use 12%-14% by weight of boiler ash powder during the making of green bricks. It will reduce dependency of quality internal fuel from far off places like Bilaspur.

Through this study, it is hoped that the small-scale brick manufacturers in and around Jhansi - Datia regions will substantially save on coal being used for firing. Financial benefits to brick manufacturing units will also occur due to low procurement cost of the waste materials.