The energy conservation measures helps in cost reduction, saving of coke and increase in the productivity of the blast furnace. A number of steps are tried in various furnaces to improve the energy efficiency of the furnace. It is found that use of lumpy ore and quality coke help in conservation of energy. Increased use of sinter in the burden also helps in energy conservation. Use of hot blast with steam humidification blast also helps in proper use of latent heat in the steam blast. Auxiliary fuel like charcoal dust, coal dust, tar, naptha and fuel oil may be used along with coke to improve the energy consumption level and cost may be reduced. The operation of blast furnace stove is to be regulated and controlled properly to avoid wastage of hot air blast and save energy. Oxygen enrichment in hot blast also can help in saving of energy. Reduction of hot blast loss at the tuyeres level may help in saving of energy. Use of top pressure recovery turbine and burden distribution system also helps in efficient use of energy supplied to the furnace. Use of sensors and sensitive control equipments can help in saving the energy loss. Improvement in the reduction reaction may save the use of coke in the blast furnace.
Proper handling of raw materials as charge may also help in conservation of energy. Conservation of energy will reduce the use of cooking coal and improve the efficiency of the furnace. Ultimately there will be reduction of cost and cheaper production of pig iron. In almost all the blast furnaces energy audit systems are installed to check the wastage of energy. Recycling of hot exhaust gases with gas cleaning facility is another way of reusing of energy. Use of solar power and wind power near the factory site may help in conserving energy and less consumption of coking coal.
Coking coal is also the most important fuel used for iron and steel making. Coking coal is converted into metallurgical coke in the coke oven. Metallurgical coke is used in the blast furnace for smelting of pig iron. Coke is also used in electric arc furnace for melting of scrap and sponge iron. Further coke is used for production of ferrochrome, ferromanganese, ferrosilicon and silico-manganese. Use of coke in the iron and steel foundries is a regular practice. Bituminous coal is used for production of Ferro coke that is used in direct smelting reduction process. Bituminous coal is also used for direst reduction of iron in the sponge iron plants. The coal used in the iron and steel industry must be strong and hard. It should be low in ash, sulphur and phosphorus content. It should be of uniform quality. Ideally, the metallurgical coal should have less than 7% of ash. The sulphur content should be less than 1% and phosphorus should be less than 0.03%. Volatile matter should be within 22-36%. The caking index of metallurgical coal should be about 22. Availability of metallurgical coal is much less in the nature. So, some of the inferior varieties of coal are treated and used in the metallurgical industries.