Magnesia Chrome Bricks Introduction
Magnesia chrome bricks are refractory products containing MgO and Cr2O3 as the main components, the periclase and spinel are the main mineral components. Magnesia chrome bricks have high refractoriness, high temperature strength, strong resistance to alkaline slag, excellent thermal stability, certain adaptability to acidic slag. The main raw materials of magnesia chrome refractory bricks are sintered magnesia and chromite. The purity of the magnesia raw material should be as high as possible.
Magnesia Chrome Bricks Features
1.High refractoriness
2.High temperature strength,
3.Excellent thermal stability
4.Strong resistance to alkaline slag
Magnesia Chrome Bricks Property
1 Chemical Composition and Mineral Composition
The chemical composition of magnesia chrome refractory bricks varies with the ingredients used. Generally, the total amount of magnesium oxide is 55% to 60%, the chromium oxide is about 10%, followed by impurities such as ferric oxide and a small amount of alumina, silica, and calcium oxide.The mineral composition of magnesia chrome fire bricks are mainly magnesium chrome spinel bricks and magnesium ferrite.
2 Refractoriness
Because the content of periclase in magnesia chrome fire brick is less than that of magnesia brick, the content of magnesia chrome spinel bricks and magnesium ferrite is much, and the melting point of their eutectic compound is relatively low. Therefore, the magnesia refractory brick of magnesia chrome brick is low, generally only 1850. ~1960°C.
3 Load Softening Temperature
The periclase crystal and the magnesia chrome spinel refractory bricks in the magnesia chrome refractory bricks are easy to form a network skeleton, because the low melting point filled in the network gap is less quality, when subjected to high temperature load, although the low melting point material softens, the mesh is soft. The skeleton can still support the load, so the load-softening temperature of the magnesia chrome refractory brick is higher, generally up to 1550 °C. The degree of refractoriness of Mgo-Cr2O3 brick is slightly lower than that of magnesia bricks, the load softening temperature is higher than that of magnesia bricks.
4 Thermal Expansion and Thermal Shock Stability
Among the magnesia chrome bricks, the content of magnesia chromium spinel and magnesium ferrite is large and the coefficient of linear expansion is small. Meanwhile, the porosity of magnesia chrome firebrick is larger than that of magnesia brick, so the thermal expansion property of magnesia chrome brick is small.
The content of calcium magnesium olivine in magnesia chrome brick is very small, it is not easy to cause anisotropic expansion stress; magnesium ferrite is dissolved in magnesia-chromium spinel, solubility is large, the dissolution temperature range is also wide, the dissolution and precipitation of magnesium ferrite It does not cause large stresses. Therefore, the thermal shock stability of magnesia chrome firebricks was good, the number of water-cooling can reach about 25 times.
5 Slag Resistance
Magnesia chrome spinel refractory bricks, which is rich in magnesia chrome bricks, is a composite of magnesium oxide and chromium oxide, and chromium oxide is a typical neutral oxide. Therefore, magnesia chrome bricks attack alkaline and acid slag,and have strong resistance.
Magnesia Chrome Bricks Specification
Index
Item |
RS-MGe6 |
RS-MGe8 |
RS-MGe12 |
RS-MGe16 |
RS-MGe20 |
RS-MGe22 |
RS-MGe26 |
RS-MGeB |
RS-MGeB10 |
| Mgo(%) |
80 |
72 |
70 |
65 |
56 |
49 |
45 |
71 |
67 |
| Cr2O3(%) |
7 |
10 |
13 |
17 |
22 |
24 |
27 |
9.6 |
12 |
| CaO(%) |
1.2 |
1.2 |
1.2 |
1.2 |
1.2 |
1.2 |
1.2 |
1.5 |
1.5 |
| SiO2(%) |
3.8 |
4 |
4 |
4.2 |
3 |
4.5 |
5 |
3.5 |
3.8 |
| Al2O3(%) |
4.5 |
6.5 |
6 |
6 |
10.5 |
11 |
12 |
6 |
6.5 |
| Fe2O3(%) |
4 |
4.8 |
5.5 |
6.5 |
7.3 |
10 |
10 |
8.5 |
9 |
| Apparent porosity(%) |
17 |
18 |
18 |
18 |
19 |
20 |
20 |
12 |
12 |
| Bulk Density (g/cm3) |
3 |
3 |
3.02 |
3.05 |
3.07 |
3.02 |
3.1 |
3.1 |
3.1 |
Cold Crushing
Strength(Mpa) |
55 |
55 |
55 |
50 |
50 |
55 |
45 |
80 |
80 |
0.2Mpa under load
Refractoriness ( ℃） |
1600 |
1600 |
1600 |
1600 |
1620 |
1620 |
1620 |
1570 |
1570 |
Magnesia Chrome Bricks Application
1.Steel making lining
2.Cement rotary kiln
3.Glass kiln regenerator
4.Refining ladle permanent layer
5.Non-ferrous metallurgical furnace, lime kiln
6.Mixed iron furnace and refractory high temperature kiln lining
Magnesia Chrome Bricks Manufacturing Process
1.Magnesia Chrome Bricks Particulate Component
The proportion of chromium ore and magnesia added is determined according to the requirements of Cr2o3 content and the actual content of CrO2 in chromium ore.
The choice of size is adjusted to the environment in which the magnesia chrome refractory brick is used.
The most common practice is to add the chrome ore as a particulate component, which is added as a fine powder and a portion of the particulate component.
When emphasizing the thermal shock resistance of magnesia chrome bricks, the granule limit of chrome ore is added or the proportion of chrome ore coarse particles is increased.
When emphasizing the corrosion resistance of magnesia chrome bricks, a fine powder of magnesium ore and a part of chrome ore is added.
2.Magnesia Chrome Bricks Mixing
In a wet mill, a mixer, and a powerful countercurrent mixer.
Bonding agent: sulfite pulp waste liquid, brine, magnesium sulfate solution, can be used, and the amount added is about 3%.
Feeding sequence: first add particles and then add binder solution, then add fine powder, etc. When the CaO content in the brick is high, the material can be used as needed to prevent brick cracking.
3.Magnesia Chrome Bricks Molding
Magnesia chrome refractory bricks can be formed by friction brick pressing, the hydraulic pressing machine can be pressed on both sides to make the density of the blank uniform. Light and heavy first, multiple pressurization is beneficial to the exhaust, preventing the brick from cracking due to elastic after effect.
4.Magnesia Chrome Bricks Drying
The purpose of drying is to remove the physical water in the green body binder to increase the height of the brick, reduce the bricks and burn waste,Generally used tunnel kiln dryer drying.
5. Magnesia Chrome Bricks Yards Refractory Brick
The code bricks of magnesia chrome bricks should be left with a larger fire channel, appropriately reduce the density of the bricks, increase the heating speed of the bricks in the pre-tropical zone.
Magnesia Chrome Bricks Manufacturer – RS Refractory Factory
RongSheng Refractory factory has been engaged in refractory material industry for more than 20 years.We have a big technological team, there are more than 15 senior designers for the furnace & kiln.They are good at different technological field, for exam, refractory bricks , castable refractory material, lightweight insulation firebricks and prefabricated bricks according to client requirement .
