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Magnesia Brick

Magnesia Brick

The raw material of Magnesia Brick (MZ) is mainly magnesite, and its basic component is MgCO3.
Magnesia brick is an alkaline refractory material, which has strong resistance to alkaline slag, but cannot resist the erosion of acid slag. At 1600°C, it can react with silica brick, clay brick and even high-alumina brick. The refractories of magnesia brick are above 2000°C, but its Refractories under Load point is only 1500~1550°C. And the temperature interval from softening to 40% deformation is very small, only 30~50°C. The Thermal Shock Resistance of magnesia brick is also poor, which is an important reason for the damage of magnesia brick.

When the liquid phase appears in the brick under high temperature, it will suddenly shrink. The thermal conductivity of magnesia brick is high, which is second only to carbon brick and silicon carbide brick in refractory products. It decreases with the increase of temperature.
The thermal shock resistance of magnesia brick is poor. Improving the purity of magnesia brick can appropriately improve the thermal shock resistance.

Various grades of dead-burned magnesite are available for the production of magnesite brick. They range from natural dead-burned materials, with MgO contents of 90% or less, to high purity synthetic magnesites containing 96% MgO or greater.

A large amount of work has been done to produce highly refractory magnesites. Since magnesia itself has an extremely high melting point, i.e., 5070°F (2800°C), the ultimate refractoriness of a magnesite brick is often determined by the amount and type of impurity within the grain. In practice, the refractoriness of a dead burned magnesite is improved by lowering the number of impurities, adjusting the chemistry of the impurities or both.

There are many types of magnesite refractories, both burned and chemically bonded. For simplification, they can be divided into two categories on the basis of chemistry. The first category consists of brick made with low boron magnesites, generally less than 0.02% boron oxide, that have lime to-silica ratios of two to one or greater. Often, the lime-to-silica ratio of these brick is intentionally adjusted to a molar ratio of two to one to create a dicalcium silicate bond that gives the brick high hot strength. Brick with lime-to-silica ratios greater than two to one are often of higher purity than the dicalcium silicate-bonded brick. This greater chemical purity makes them more desirable for certain applications.

The second category of magnesite brick generally has lime-to-silica ratios between zero and one, on a molar basis.

These bricks may contain relatively high boron oxide contents (greater than 0.1% B2O3) in order to impart good hydration resistance. Sometimes, for economic reasons, these bricks are made with lower purity natural dead burned magnesites with magnesia contents of 95% or less. At other times, the brick is made with very pure magnesites with MgO contents greater than 98% for better refractoriness.
Magnesia Brick for Glass Furnace Regenerator 1
Magnesia Birck (MZ) was made primarily of pure magnesite of various sizes and burnt under media to high temperature. It has excellent resistance to strong alkaline slag attack, alkaline vapour erosion, oxidation-reduction erosion and good thermal conductivity. However, it is average in thermal fatigue resistance, and wear-resistance erosion. It is poor in thermal shock stability, and bad resistance to acidic slag attack. It was used widely in working lining, safety linings and permanent linings at traditional Steel and Non-ferrous Metal Smelting Furnaces (OHF Furnaces, EAF Furnaces, Converters, Mixers, Flash Smelting Furnaces, Copper Converters, Reverberatory Furnaces etc.). After pitch-impregnated, resistance of slag attack and thermal shock stability will be highly enhanced and improved.

We can produce Harbinson Walker International standard Magnesia brick, such as:

N 90 B CH: NARMAG 90B CH
N B: NARMAG B
SN B CH: SUPER NARMAG B CH
SN HF: SUPER NARMAG HF

OSYMEN

MgO

SiO2

A.P

B.D

C.C.S

R.U.L

%

%

%

g/cm3

MPa

(Ta)°C

MZ-91

91.0

4.0

18.0

2.90

50

1560

MZ-93

93.0

3.5

18.0

2.92

50

1620

MZ-95A

95.3

1.8

16.0

2.96

65

1660

MZ-95B

95.0

2.0

17.0

2.95

60

1650

MZ-95C

94.5

2.5

18.0

2.90

60

1600

MZ-96A

96.3

1.0

16.0

2.98

65

1680

MZ-96B

96.0

1.2

17.0

2.95

60

1650

MZ-96C

95.5

1.5

17.0

2.93

60

1620

MZ-97A

97.2

0.8

16.0

3.02

70

>1700

MZ-97B

97.0

1.0

17.0

3.00

65

>1700

MZ-97C

96.8

1.2

17.0

2.96

65

1650

MZ-98A

98.2

0.8

15.0

3.05

75

>1700

MZ-98B

98.0

0.8

16.0

3.02

70

>1700

MZ-98C

97.5

1.0

16.0

3.00

65

>1700

 AP: Apparent Porosity   |  BD: Bulk Density  |  CCS: Cold Crushing Strength  |  RUL: Refractories Under Load  |  TSR: Thermal Shock Resistance

Last updated: 2024-01-03
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