One of MgO-CaO series refractory material’s shortcoming is weak thermal shock resistance. To improve thermal shock property of magnesia dolomite bricks, zirconia powder, zirconia grain, calcium zirconate and magnesia calcia zirconia composite are added into magnesia dolomite raw material. Various tests suggests that when 2% of ZrO2 is added into the raw material, magnesia dolomite zirconia bricks’ thermal shock resistance ability can be significantly enhanced, but high temperature rupture strength will decrease. So different quantity and granularity of ZrO2 can be added into the raw material to produce proper magnesia dolomite zirconia bricks for different applications.
MgO-CaO-ZrO2 Bricks Physiochemical Index
Item
MGGZ-1
MGGZ-2
MGGZ-3
MGGZ-4
MGGZ-5
MGGZ-6
MGGZ-7
MgO%
73
82.3
58
48
39.5
60
75
CaO %
23.5
5.8
37
48
56.6
37
21
ZrO2 %
2.0
11.3
2.7
1.8
2.0
2.0
1.8
Al2O3 %
0.1
/
0.5
0.5
0.5
0.4
0.6
Fe2O3 %
0.4
/
0.8
0.7
0.8
0.6
0.7
SiO2 %
0.5
0.3
0.6
0.6
0.8
1.1
0.9
Apparent porosity %
16.6
15.3
16
15
14
13
12
Bulk density g/cm3
2.87
3.09
2.83
2.9
2.9
2.98
3.02
Compression strength Mpa
34
46
45
/
/
/
90
High T rupture strength Mpa(1400℃, 0.5h)
5.3
3.6
/
/
/
/
4.2
Magnesia Dolomite Zirconia Bricks Application
Magnesia dolomite zirconia brick is a good replacement of magnesia chrome brick, and can be widely used in AOD, VOD and other out-furnace refinery equipments. VOD furnace slag line zone, where slag abrasion, steel liquid scouring is severe, mainly adopts sintered magnesia dolomite zirconia bricks. Furnace wall can choose lower grade sintered magnesia dolomite bricks or pitch binding unburned magnesia dolomite bricks. When applied in AOD furnace tuyere, where thermal shock is a big problem, good thermal shocker resistant magnesia dolomite zircon bricks are a good choice. The rest part of the furnace wall can adopts ordinary sintered magnesia dolomite bricks. In large scale cement kilns, compared with magnesia chrome bricks, magnesia dolomite zircon bricks not only have lower production cost, but also avoid Cr6+, it is an ideal replacement of magnesia chrome bricks, and will have a promising applications.
