|
December, 2000 IN order to meet ever rising demand for electricity, installed power generation capacity of India was increased by 67 times from 1947 to 1998. In 1947, we had just 1331 MW of power. In 1998, it become 89167 MW. Yet there is no respite. Demand continues to outstrip supply. And most part of this generation capacity is thermal based. Taking example of North India alone, 12977 MW of total 24782 MW capacity is thermal power. Further, out it, 9937 MW is based. In North India alone, we are producing 60,000 MT of ash everyday. Under the circumstances, it become essential to convert their residue i.e. flyash — into resource. The necessity of effective utilisation of flyash, has therefore, gained extreme importance. Best utilisation of flyash has been found to be in manufacture of cement, bricks and in embankments. Bricks are the most common building material used by the man since ancient times. Ever rising demand for dwelling units is directly resulting into an increase in demand of bricks. Use of flyash in bricks can therefore dilute the problem of disposal of this hazardous material to a large extent. In addition, the depletion of fertile crest of earth, now underway to fulfill the demand of clay for manufacture of bricks, can also be slowed down. Flyash can be used in combination with clay or with lime and sand to produce clay-flyash bricks and flyash-sand-lime bricks respectively. Production of clay flyash bricks was taken up by setting up a bricks kiln at Lehra Mohabat with the objective to produce 2 crore such bricks of first-class quality apart of the second-class and third-class bricks. The kiln has produced more than 1.8 core of first class clay-flyash bricks of which about 1.5 crore stand consumed by now. The cost of conventional bricks varies from place to place. The variation is quite large and ranges from Rs 12000 to Rs 2200 per 1000 bricks. Machine moulded terracotta colour bricks cost Rs 2200 per 1000 no while hand moulded clay bricks cost between Rs 1200 to Rs 1700 no bricks. at Lehra Mohabat or in Bathinda region, conventional clay bricks of first class quality are available at Rs 1300 per 1000 bricks. Taking into account the extra labour cost, power consumption, depreciation of machinery and interest charge on capital investment, the cost of clay flyash bricks being produced at Lehra Mohabat works out to be about Rs 1475 per 1000 no bricks. The cost of clay flyash bricks is thus higher by Rs 175 per 1000 no. The difference in cost of clay flyash bricks and conventional bricks will, however, vary from place to place. It has been noted that hand-mixing, hand-moulding of clay flaysh bricks is not possible. Proper mixing and blending of soil and flyash do not take place in hand mixing. However machine-mixing, hand-moulding is possible in these bricks. Clay-flyash bricks, when tested for various physical requirements laid in IS 13757-1993, give satisfactory results. These bricks need to be tested for compressive strength, water absorption and efflorescence. Actual results received on testing of these bricks show that compressive strength of these bricks is very high in comparison to the minimum strength requirement of 105 kg/sq cm prescribed for conventional burnt clay bricks. The water absorption and efflorescence results are also significantly better than those noted for the conventional bricks. Overall, the test results strongly plead for addition of flyash to clay for the manufacture of bricks. It has been observed that the buildings where clay flyash bricks have been used show lesser signs of dampness in comparison to those using conventional bricks. This is because of low porosity of these bricks. Comparison of machine-mixed, machine-moulding bricks with and without use of flyash was also made at the kiln site, keeping all other conditions same, to determine the effect of flyash on the strength of bricks. It was found that that average compressive strength of clay flyash brick was 300 kg/cm while that of bricks without flyash was 190 kg/cm. This shows that addition of flyash to soil has a positive effect on the strength of bricks. A saving in fuel consumption has been noted while manufacturing clay flyash bricks. A flue consumption of 11 to 12 tonne of coal for production of one lakh clay-flyash bricks has been noted. This is 3 to 4 tonne lesser than the normal corresponding consumption of coal. This awing occurs due to presence of unburnt carbon in the flyash. Percentage of unburnt carbon in flyash may vary from place to place depending upon the efficiency of boilers of the thermal plant. In general, percentage of 6-12% unburnt carbon in flyash has been noted. The above saving, however, is for an unburnt carbon content of 3-6% only. The quality and calorific value of coal also determines its consumption. If good quality coal is used, the consumption may be further reduced. The rates of coal vary from Rs 3000/- to Rs 500/- per metric tonne. When Assam coal of medium variety, costing around Rs 4000/- MT was used, its consumption per lakh of bricks was found to be 10 to 11 tonnes only. More than 12000 cubic metre flyash has been consumed in the manufacture of bricks at Lehra Mohabat kiln site. This makes little percentage of total flyash generated by the unit in a year. Significant percentage can be achieved if the Gazette notification is followed and all the kilns within 50 km radius begin to use flyash in the manufacture of bricks. In addition to consumption of flyash, there is an equal saving of soil also. Keeping in view the above observations made during the manufacture of clay-flyash bricks, the following steps if taken will help in large scale promotion of clay flyash bricks: Incentives to be given to brick kiln owners: A few benefits are already available to the brick kiln owners choosing to produce clay flyash bricks. These include a) sales tax exemption by the government, b) excise duty exemption on ash based products and c) A category incentives by the industry department such as 30% subsidy on building and fixed machinery. In addition, there are saving in fuel and clay. Yet the brick manufacturers are reluctant to switch over to clay flyash bricks. The following incentives need to be given further to the brick kiln owners to promote clay flyash bricks: 1. Low interest loans should be given to meet the higher initial investment. The machinery purchased by the manufacturer should be hypothecated to the department extending the loan till its full recovery. 2. Easy availability of flyash to the kiln owners should be ensured. It should be the responsibility of the thermal plant authorities to supply free-of-cost flyash to the brick kiln owners. In the initial years — till the time clay flyash bricks become popular — cost free flyash should be provided by the thermal plants at all kiln sites falling within 50 km radius of them. 3. Power connection should be given to clay-flyash brick manufacturers on a priority basis. 4. Kilns producing clay flyash bricks should be declared seasonal industry. On average basis, kilns remain closed for 4 months in a year due to rains or extreme weather. During these months, they have to deposit the minimum electricity charges to the SEBs. If declared as seasonal industry, they will be exempted of depositing these charges. 5. Industry department should maintain a separate list of these kilns for A-category incentives. Now, coupled with other industries having similar benefits, it takes a long time to pay the subsidy to the brick manufacturers.
Steps to be taken by PWDs and SEBs: Items of brick-work in clay flyash bricks should be added to the common schedule of rates. A higher rate in comparison to that for brickwork with conventional bricks should be allowed to accommodate higher cost of clay flyash bricks, however, after making fresh analysis with respect to the reduction in their cost that might arise due to the benefits given to the industry. The work-specifications should be revised and items with clay flyash bricks should be added to the new tender documents in place of normal brickwork items. Government departments should declare it compulsory to use only clay flyash bricks in all public works. If this is done, major purpose will be achieved. 3. State Electricity Boards should pass a regulation to give power connection to brick manufacturers producing clay flyash bricks on priority basis. 4. Thermal plant authorities should resolve to supply flyash free of cost at kiln sites within 50 km radius and the cost of transportation should be borne by the thermal plant authorities. This will help them in disposal of flyash as well as in meeting with environment-protection regulations. Amend Gazette Notification no 563: The gazette notification of September 14, 1999, issued by Ministry of Environment and Forests Government of India binds the brick manufacturers to use atleast 25% ash on weight to weight basis in the manufacturer of bricks. As per notification, this stipulation can be relaxed or waived by the State/Union Territory Government only in case of non-availability of ash from thermal power plants. The notification needs to the further amended to the effect that the percentage of ash to be used in bricks can be reduced if the local soil does not contain sufficient percentage of clay in it. The authority under para 1 (2) of the notification should be empowered to decide the percentage of ash to be used in the local soil for production of best quality bricks. Based on actual experience in production of clay flyash bricks, it is concluded that steps elaborated above need to be taken to promote the production and use of clay flyash bricks. These steps will help brick manufacturers in shedding unfounded fears and adopt use of flyash in bricks thus contributing towards utilsation of flyash and save environment. These steps will also help in reduction in cost of production of clay-flyash bricks, further helping the consumer to switch over to clay-flyash bricks as he will get machine moulded and stronger bricks at a cost comparable to that of conventional bricks.
|
