Refractory gunning mix is the kind of refractory material applied by high speed current gunning method. Refractory gunning mix includes gunning material used for damaged lining patching and coating material used for new lining construction. Refractory gunning work can be done without mould, so this method is labor saving and have shorter working schedule. Gunning refractory mix can be classified into two categories according to material physical states: cold gunning method and molten spraying method.
1. Basic Refractory Gunning Mix Description
Basic refractory gunning mix is the kind of gunning material which’s main components are MgO or MgO and CaO. Basic gunning mix is mainly used as hot patching material for electric furnace, converter, steel ladle and nonferrous metal smelting furnace, etc. Basic refractory gunning material can also be used as coating material of continuous casting tundish. Hot patching material usually adopts dry spraying patching method, but tundish working lining coating material usually adopts wet spraying method.
Dry basic gunning material used for converters and electric furnaces are made from sintered or fused magnesia sand or magnesia calcia sand, so it is usually called magnesia gunning material or magnesia calcia refractory spraying material.
Wet basic gunning material used for tundish are made from sintered magnesia( MgO-CaO sand), binder, plasticizer and organic fiber.
Tundish Wet Basic Gunning Mix Physiochemical Index
Item
BGM-1
BGM-2
BGM-3
MgO %≥
80
65-75
55-65
SiO2 %
4-6
≤5
≤5
CaO %
—
8~10
20~35
Bulk Density g/cm3 （110 ℃, 24h）
1.6~2.0
1.7~2.0
1.7~2.0
Rupture Strength (110℃, 24h) Mpa
1.5~2.0
1.6~2.3
2.0~2.5
linear change rate % (110℃, 24h)
-(1.0~1.5)
-(1.2~1.8)
-(1.2~2.5)
Thermal Conductivity W.(m.K)-11000℃
≤0.6
≤0.6
≤0.6
2. High Alumina Silicon Carbide Carbon Gunning Material
High alumina silicon carbide carbon gunning material is made from high alumina clinker, silicon carbide, carbon aggregate and fines, calcium aluminate cement and silicon dioxide binder and additives. Al2O3-SiC-C gunning material can by applied by dry gunning method or wet spraying method.
Al2O3-SiC-C Gunning Mix Physiochemical Index
Item
HALG-A
HALG-B
Al2O3 %≥
67
70
SiC %
14
10
Fe-C%
3
3
Bulk Density g/cm3 （110 ℃, 24h）
2.56
2.75
Apparent porosity%（110 ℃, 24h）
18.5
21.6
Rupture Strength (110℃, 24h) Mpa
11.0
2.5
linear change rate % (1450℃, 3h)
-0.50
+0.11
Adding Water quantity %
7.5
6.8
High Alumina Silicon Carbide Carbon Gunning Material Application
High alumina silicon carbide carbon wet gunning mix is mainly applied in constructing or patching the inner lining of blast furnace tapping channel, torpedo tank, iron mixing furnace and cupola. Carbon free high alumina silicon carbide wet gunning mix is mainly used to build or amend the inner lining of garbage incinerator and rotary kiln discharge hole.
