Which refractory material is used in hearth of blast furnace?
The main refractory lining of blast furnace hearth is composed by carbon blocks that operates in continuous contact with hot gases, liquid slag and hot metal, in temperatures above 1550 ºC for 24 hours a day.
What is a blast furnace lined with?
Blast furnaces are lined by carbon and graphite refractory bricks to protect the integrity of the vessel.
What is hearth in blast furnace?
This lowest region in the blast furnace is exposed to liquid iron (hot metal) and liquid slag which are in direct contact with the refractory materials, causing severe erosion and chemical and thermal attack of the hearth lining. The hearth is the lowest, but the most important part of the blast furnace.
Why is the inside of a blast furnace lined with fire bricks?
The inside of a blast furnace is extremely hot (up to 1500 ºC in places). The inside surfaces have to withstand these extremely high temperatures without cracking. The inside is lined with firebricks made from special refractory materials. Therefore the furnaces are well insulated.
What is a refractory lining?
A refractory lining usually comprises a safety or backup layer behind the working lining in contact with the furnace contents. The whole body is encased in a metal shell. In particular, the designer of any refractory lining should be aware of the free thermal expansion and hot strength of all materials used.
Why graphite is used in blast furnace?
The blast furnace method and the electric arc furnace method. The electric arc furnace method recycles used iron scrap by melting it in an electric arc furnace. It is the graphite electrodes inside the furnace that actually melt the iron. Graphite has high thermal conductivity and is very resistant to heat and impact.
What are the main parts of a blast furnace?
The components of a blast furnace include the Charge, exhaust gas outlet, charging bells, gas outlet, tuyeres, taphole, bustle pipe, slag hole, refractory lining, and conveyor system.
What is the temperature C normally maintained in blast furnace hearth?
The blast is heated in hot stoves to 1000 – 1400 °C and distributed to the tuyeres. The number of stoves is usually three or four. The hearth is lined with carbon bricks and sometimes completed with a so-called ceramic cup.
Where and how are refractory bricks used in different types of furnaces?
Refractory bricks (fire brick): A fire brick, firebrick, or refractory is a block of ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency.
What is refractory lining in furnace?
Refractory lining is basically a protective layer installed inside the furnace to protect the steel structure from high temperatures. Refractory bricks or monolithic refractories can be used for refractory lining. A professionally placed lining will increase the lifetime of the furnace and lower the energy costs.
What is the thickness of refractory lining in BOF?
This consist of a thinner safety lining to protect the shell usually of thickness ranging from 150 mm to 225 mm and a thicker working lining usually of thickness ranging from 450 mm to 750 mm.