The blast furnace is controlled from the top. The solid charge is distributed uniformly from the top of the furnace. Blast furnace is also controlled by controlling temperature
and supply of hot blast. The flow of liquid metal and slag is controlled in such manner that the slag is sent to the slag dump. The molten pig iron is cast into pig casting machines.
In case of steel making, the molten pig iron is transferred to the steel making shop. A control mechanism is established to control all the operation in the blast furnace. Use of
software's made the control system more effective.
BLAST FURNACE PROCESS
In the blast furnace, iron ore, coke and limestone are put as charge materials. Hot air blast is blown through the charged materials. The oxygen from the preheated blast combines with
carbon to generate heat and carbon monoxide. The oxygen is separated from iron ore and reacts with carbon. Carbon monoxide is formed by reaction of carbon and oxygen. In this way oxygen
is removed from iron ore.
The carbon monoxide moves upward through the charge and reacts with oxygen of iron ore. Then it moves as exhaust gas. The lime stone reacts with silica, alumina and other impurities to form slag.
The limestone is broken into lime and carbon dioxide. The carbon dioxide moves up as exhaust gas. The lime reacts with silica and alumina to form slag. The molten iron
trickles down to bottom of furnace as molten metal.
Fe2O3 + 3C = 2Fe + 3CO
2C + O2 = 2CO
CaCO3 = CaO + CO2
MgCO3 = MgO + CO2
The performance and efficiency of a blast furnace depends on productivity and consumption of coke. When the rate of productivity is higher and consumption of coke is lower, then the furnace is efficient. The charge quality also indicates higher performance of the furnace. The blast furnace may be termed efficient when it can handle different size of iron ore. The quality of raw material helps in improving the performance. The design of the furnace and the metallurgical process adopted contributes towards efficient operation of blast furnace. The furnace is found to be efficient when maximum amount of blast is blown into the furnace and the charge material is permeable to this blast. It is found that most of the blast furnace runs efficiently when lumpy ores are used as charge materials.