Induction furnace is steel smelting equipment, which can generate strong electromagnetic field when the induction coil is powdered on. So raw material such as scrap steel in induction furnace will generate eddy current, then be heated and melted. Ferric alloy and other metallurgical ingredients can be added into raw material to make steel with required composition and quality and be casted into needed shape.
Generally, induction furnace’s size is small, mainly used to make castings and steel for precision casting. It is also used to smelt stainless steel. Induction furnace main refractory material is ramming mass. For cast iron smelting induction furnace, low price quartz ramming mass is usually adopted, the service life is between 20~40 times. When smelting steel for precision casting, smelting temperature is higher, smelting condition is also severer, quartz ramming mass can’t meet using requirement, so magnesia dry ramming mass, alumina magnesia dry ramming mass and magnesia chrome dry ramming mass are popularly used. Some induction furnaces also adopt alumina silica ramming mass or crucibles.
Induction Furnace Lining Refractories
Item
MgO %
Cr2O3 %
Fe2O3 %
Al2O3 %
CaO %
SiO2 %
Quartz ramming mass
/
/
/
/
/
98
Magnesia ramming mass
91
/
4
1
2.5
1.5
Magnesia ramming mass
96
/
<1.5
/
/
<2
Magnesia alumina ramming mass
90
/
0.5
8
2
0.5
Magnesia alumina spinel ramming mass
10
/
/
87
1
1
Magnesia chrome ramming mass
58
21
12
6
1
1.5
Magnesia spinel ramming mass
80
/
/
17
/
/
High alumina ramming mass
>70
/
/
/
/
<26
When crucible is used in induction furnace, the gap between crucible and induction coil should be crammed firmly by dry ramming mass. This method is convenient for replacement and can increase efficiency of equipment. This type of refractory crucible is casted by castable which’s chemical composition is similar to dry ramming mass, then hardened and dried. High quality basic dry ramming mass or corundum spinel ramming mass have longer service life, can reach to 70 times or more.
Dry ramming mass built furnace lining has many advantages:
Low cost;
Not easy to crack, rare odds of steel leakage and permeation.
Sintering layer is thin, easy for furnace detachment.
Not sintered dry ramming mass has low density, so heat preservation effect is good.
Water free, can directed be used for production without drying, can not only decrease energy consumption but also enhance efficiency.
