Classificatio

Refractories Classification Points : Refractories Classification, Hearth Refractories, Side Wall Refractories, Special Features, Roof Refractories, Ladle Refractories According to the area of application, the refractories are categorized as:
a) Hearth Refractories
b) Side wall Refractories
c) Special Features
d) Roof Refractories
e) Ladle Refractories
(a) Hearth Refractories Hearth refractories must resist slag attack and contain the molten charge at elevated temperatures of 1600-1759°C. In case of conventional stainless steel production, occasionally, temperature goes upto 2000°C. The hearth is constructed either from dry remmed monolithic or high quality fired Magnesia brick, depending upon furnace operation. (b) Side Wall Refractories The refractories used in EAF side bba1ls withstand the following severe operating conditions:
I. In localized areas as high as 2000°C temperatures are attained in hot spot areas which vary base on furnace operation and type.
II. Refractories must withstand tF’ stress caused by thermal cycling in-between heats, power break down etc.
III. Abrasion resistance to resist mechanical damage during Charging. (c) Special Features I. High refractoriness as carbon does not form any low eutectic compound by combining with magnesia.
II. Excellent corrosion and erosion resistance.
III. on-wettability towards molten steel and slag as it has low A.P.
IV. High thermal conductivity, results in fast heat dissipation from Hot face to cold face thus, reducing wear rate.
V. High hot strength at elevated temperatures. (d) Roof Refractories Selection of refractories for EAF roofs means that.
(a) The refractory must have good spilling resistance.
(b) Roof brick must have adequate refractoriness to withstand high temperatures.
(c) The brick must be produced to very tight size tolerance to get optimum stability in the roof structure.
(d) The refractory bricks should be resistant to penetration of metallurgical fumes, iron oxides and lime.
(e) The roof bricks must have good erosion resistance.
(f) The bricks must exhibit a high hot strength to withstand stress caused in the roof, due to roof swinging. (e) Ladle Refractories Continuous Casting, vacuum Degassing and alloy additions, demand high tapping temperature result is accelerated refractory wear due to chemical action with slag.
To increase the ladle lining life, zoned lining construction may be used based on the wear profile. If high basically slags are handled in continuous casting units the slag zone may be lined with Mag-chrome or Chrome—mag bricks or MgO-C bricks containing 10% carbon.