Refractory material
Properties
Introduction
1
2
3
4
2
Classification
Application
Introduction
3
1
History and importance
Non-metallic ceramic material or product whose chemical and physical properties allow it to be used in a high temperature environment
1318 Aminabad refractory factory in Tehran with a daily capacity of 5,000 tons
Azar refractory in Isfahan with production capacity of 40,000 tons of bricks and mass
The urgent need of steel industries and … Refractories:
Comparison with refractory metals:
More resistance to creep, pressure, heat
Low thermal conductivity
Less deformation
Economic factor
4
4
Refractory requirements
The general requirements of a refractory
Bearing capacity against loading and abrasion forces
Low thermal expansion coefficient
Heat storage capability
Ability to withstand contact with molten metals, hot gases and erosion) and …
Ability to withstand sudden changes in temperature
High temperature tolerance
Pressure tolerance in operating conditions
Properties refractories
5
Classification based on chemical composition
6
Basic Refractories
Neutral Refractories
Stable to acids but attacked by alkalis
Main components: SiO2, ZrO2
Stable to alkaline but reacts with acids.
Magnesia (MgO)
Dolomite (MgCO3 + CaCO3) and chrome-magnesia (Cr2O3 + MgO).
Stable to both acids and bases
Alumina (Al2O3), chrome ( Cr2O3) and carbon
Classification based on raw material
7
Magnesium refractories
Dolomite refractories
Chromite refractories
Graphite refractories
Silica refractories
Sillimanite refractories
Refractory clay
Forsterite refractories
Silica carbide refractory
Bauxite refractories
02
03
04
05
01
10
09
08
07
06
Alumina silicate refractory
Oxide refractories such as beryllium oxide, cesium, zirconium, tantalum and niobium.
10
12
8
Silica refractories
Classification based on raw material
Magnesite refractories
MgCO3
Advantages:
No softening until fusion point is reached;
High refractoriness;
High resistance to spalling flux and slag,
Volume stability
More than 90% SiO2, less than 8.5% of oxides of aluminum, titanium, iron and calcium
Iron & steel, glass industry
47.6% MgO
52.4% CO2
Desirable Magnesite
SiO2 ، Al2O3 ، CaO
CaO less than 2%,
SiO2 less than or equal to 3% minimum MgO 92%
High slag resistance, especially lime and iron
Classification based on raw material
Dolomite refractories
CaMg(CO3)2
Graphite refractories
Made of graphite and a small amount of sticky clay
Used only in reducing conditions
Graphite reduces the
Wettability properties of corrosive slag
Increases thermal conductivity
Improves thermal shock resistance
9
Melting point 1700 °C
Major consumer: Iron and steel industry
High purity dolomite and low iron are suitable for refractory preparation
Bakhtaran Dolomite, Isfahan (Hassan Robat)
Low resistance to electric shocks
High thermal resistance
Classification based on raw material
Chromite refractories
Alumina silicate refractory
Al2O3 SiO2
Chrome- magnesite
15-35% Cr2O3 and 42-50% MgO
Used for critical parts of high temp furnaces
Withstand corrosive slags
High refractories
Magnesite-chromite
>60% MgO and 8-18% Cr2O3
High temp resistance
Basic slags in steel melting
Better spalling resistance
10
4(FeCr2O5)
Thermal resistance
Chamotte refractories with 25 to 45% alumina are used as heat transfer resistors that are sensitive to heat shock in coke oven cells and the outer wall of pots.
Refractory clay, bauxite, sillimanite, andalusite, kyanite, mullite and corundum
Classification based on raw material
Silica carbide refractory
Oxide refractories
Sic
High thermal resistance
High abrasion resistance
Withstand thermal shocks
High refractoriness
Aluminum, Beryllium, cesium, zirconium, tantalum and niobium oxide
11
High thermal resistance
High abrasion resistance
Resistance to thermal shocks
High price
Glass furnaces, insulating refractory
ZrO2
Classification based on physical shape
12
Unshaped Refractories
Shaped refractories
13
Unshaped Refractories
14
Castable refractories
Steel and iron industry
Copper industry
Aluminum industry
A
B
C
Application of refractories material
D
Cement industry
Glass industry
E
D
15
Steel industry
16
Magnesit-graphite
major consumer of refractory materials
70%
Sub hearth
Working hearth
Side walls
The main side wall
Hot spots
Slag level
Burner valves and slag outlet
Ceiling
nozzles
Blast furnace
Coke oven
Torpedo ladles
Basic oxygen Furnace
Electric arc Furnace
Induction furnace
Twin Hearth Furnace
Energy Optimizing Furnace
Secondary Refining Ladles
Slide gate Refractories
Tundish Refractories
High quality magnesia bricks
Monolithic refractories
Magnesium-graphite with metals
Magnesit
Graphite
10% G
20% G
Alumina refractories
Zirconium silicate refractories
*Indications*
Copper industry
17
Chromite-magnesium refractories Aluminosilicate materials Mortars and monolithic materials
Smelting Process
Magnesite chromite refractories direct bonded
Magnesite-chromite refractories with strength, at high temperatures and resistant to thermal shocks
Converter
Slag cleaning Furnace
Magnesite-chromite refractories direct bonded
Glass industry
High resistance to alkaline vapors
High strength at high temperatures
High corrosion resistance
18
Refractory insulation materials
Ceiling
Smelter / refiner
Regenerators
High resistance to thermal shock
High strength at high temperatures
Creep resistance
High heat transfer
Zirconia refractory materials
Aluminum industry
19
Aluminum penetration resistance
High strength
A
launders
High alumina bricks with phosphate binder
Castable refractories with little or no cement
Anode Baking Furnace
Melting/Holding Furnace
Induction Furnace
ladles
High corrosion resistance
High duty fireclay
High alumina bricks
ی
Cement industry
20
Dolomite refractories
Magnesia-chrome Spinel
Magnasia-Alumina Spinel
Fireclay
High alumina
Pre Calciners
Rotary furnace
Coolers
Ducts
references
21
[1] Schacht, Charles. Refractories handbook. CRC Press, 2004.
[2] Nemati, Ziarat Ali, Ceramic refractories, Tehran: Scientific publications of Sharif University of Technology, 2003
[3] Gerald Rothschka, translated by Dr. Behzad Mir Hadi, refractory materials, second edition, September, Iran University of Science and Technology, 1999.
[4] www.PDHcenter.com
[5] www.rasekhoon.net
References
TH NK
YOU
Sep, 2021