1. CARBON GRAPHITE REFRACTORIES AND CERAMIC GRAPHITE
PRESENTATION BY : PRAVEEN KUMAR
S5 , MTG
ROLL NO : 23
AJCE

2. WHAT IS A REFRACTORY ?
Materials which withstand high temperature and do not fuse even at very high temperature.

3. Types of refractories There are three type of refractories
Acidic refractories
Basic refractories
Neutral refractories

4. CARBON GRAPHITE REFRACTORIES

5. CARBON GRAPHITE REFRACTORIES
The basic definition…
Graphite is a crystalline form of carbon and its natural deposit is known as “Plumbago”.
Coke has been used as a cheap substitute for graphite but not satisfactory.
Bonding materials for carbon refractories are usually tar or pitch (free from ammonia or light oils).
Graphite is found in Karnataka, Bihar and Orissa.

6. CARBON GRAPHITE REFRACTORIES
Coke is crushed
Stored dry
Spread it on floor
Add hot tar/pitch
Shovel thoroughly
Moulded in wood
Cool the mould
How its made?

7. CARBON GRAPHITE REFRACTORIES
Precautions while manufacturing…
The coke used must contain less than 8% ash.
Crushing or grinding must reduce the size of coke to 1-2mm size.
While mixing with shovels, be quick so as to avoid formation of lumps.
The moulds used (wooden or iron) must be oiled before use.
The bricks must be cooled in ventilated rooms.
Exposure to sunlight can make them soft.

8. CARBON GRAPHITE REFRACTORIES
Properties…
Graphite is infusible and sublimes at 3600°C.
It is not attacked by any slag or chemicals except in the presence of oxygen as it oxidises at elevated temperatures.
It is resistant to thermal shocks.
Have high thermal as well as electrical conductivities.
Porosity value vary from 20% – 25%.
They are light grey in colour and give a ringing sound when struck.
Cold crushing strength is about 350 Kg/Cm2.

9. CARBON GRAPHITE REFRACTORIES
Uses…
Extensively used in lining the hearth and bosh of the Blast furnace.
Also used in furnaces where temperature is high and the atmosphere is non-oxidising.
They may be also used in the lower stack wall of the Blast furnace also.
Iron and slag runners are also lined with carbon refractories due to lower shrinkage.
Graphite crucibles of varied sizes are used for melting cast iron, aluminium, copper etc.
Carbon is used as a ramming mixture with tar for construction of electrolytic cells.

10. CARBON GRAPHITE REFRACTORIES
How does it look like?

11. CERAMIC -GRAPHITE REFRACTORIES

12. CERAMIC -GRAPHITE REFRACTORIES
The basic definition…
New class of carbon refractories.
Examples are magnesia graphite and alumina graphite.
Composition of Magnesia Graphite Bricks,
C = 5-20%
CaO = %
SiO2 = %
Fe2O3 = %
Al2O3 = %
MgO =

13. CERAMIC -GRAPHITE REFRACTORIES
Properties…
High thermal spalling resistance.
Reduced specific refractory consumption.
Resistance to action of slags.
Cold crushing strength after tempering varies from Kg/Cm2.
Bulk density after coking is gm/cc.
Bulk density after tempering is gm/cc.
Very high fusion point.

14. CERAMIC -GRAPHITE REFRACTORIES
How does it look like?

15. THANK YOU…