Claims:We Claim:
1. Magnesia carbon based refractory composition comprising:

Sea Water Magnesia (SWM) (Coarse) 74 – 87 % by wt.
Sea Water Magnesia (SWM) (Fines) 8 – 12 % by wt.
Aluminium powder 1.5 – 2.5 % by wt.
Graphite 4 – 6 % by wt.
Amorphous Carbon Nano Tube (ACNT) 0.05 – 0.15 % by wt.
Phenol-formaldehyde resin 4 – 5 % by wt.

2. Magnesia carbon based refractory composition as claimed in claim 1 which is magnesia carbon based refractory brick composition comprising:
Sea Water Magnesia (SWM) (Coarse) having particle size ranging from 3mm to 4.5 mm and about 23-28 % by weight,
Sea Water Magnesia (SWM) (Coarse) having particle size ranging from 1 mm to 3mm and about 28-31 % by weight,
Sea Water Magnesia (SWM) (Coarse) having particle size ranging from 0.5mm to 1 mm and about 23-28 % by weight,
Sea Water Magnesia (SWM) (Fines) having particle size below 0.044 mm and about 8-12 % by weight,
Aluminium powder (Fines) having particle size below 0.074 mm and about 1.5-2.5 % by weight,
Graphite having (Fines) having particle size below 0.5 mm and about 4-6 % by weight,
Amorphous Carbon Nano Tube (ACNT) (Fines) having diameter below 3x10-5 mm (30 nm) and about 0.05-0.15 % by weight,
Phenol-formaldehyde resin (Liquid) as binder having viscosity more than 250 cps at 250C and about 4-5 % by weight.
3. Magnesia carbon based refractory composition/bricks as claimed in anyone of claims 1 or 2 wherein said Sea Water Magnesia (SWM) comprises
MgO (Min.), % 97
CaO (Max.), % 2
SiO2 (Max.), % 0.35
Fe2O3 (Max.), % 0.20
Al2O3 (Max), % 0.12
B2O3 (Max.), % 0.03
Avg. Crystal size (Min.), µ 100

4. Magnesia carbon refractory composition/bricks as claimed in anyone of claims 1 to 3 wherein said Aluminium powder comprises
Al (Min.), % 99.5
Fe (Max.), % 0.40
Si (Max), % 0.15
Size (Max.), mm 0.074

5. Magnesia carbon refractory composition/bricks as claimed in anyone of claims 1 to 4 wherein said Graphite comprising
Fixed Carbon (Min.), % 96
NGC (Max.), % 0.50
Volatile matter (Max), % 2.0
Moisture (Max.), % 0.50
Size Range
(+) 44 mesh BSS (Max.)
(-) 60mesh BSS (Min.)
(-) 72 mesh BSS (Min.)
(-) 100mesh BSS (Min.)
7.0
80
60
30

6. Magnesia carbon refractory composition/bricks as claimed in anyone of claims 1 to 5 wherein said Amorphous Carbon Nano Tube (ACNT) comprising
Purity (Min.), % 98
Outer diameter, nm 10 – 30
Length (Max), µm 15
Specific Surface area (Min.), m2/gm 200
Colour Black

7. Magnesia carbon refractory composition/bricks as claimed in anyone of claims 1 to 6 wherein said Phenol-formaldehyde Resin comprising
Type Resol
Non-volatile matter (%) 68-72
Fixed carbon (%) 35-40
Viscosity (cps), at 250C 250-300
Sp.Gravity at 200C 1.17-1.19
pH at 200C 6.5-7
Moisture Content (%) 8-10
Free Phenol (%) 14 (± 2)
Free Formaldehyde (%) 0.8 (± 0.2)
Shelf life (days) min 45
Water miscibility at 250C (Resin: water) 100:50 min
Ash content % (max) 0.2
Gel formation
At 800C 9 hrs
At 1000C 1.5hrs
At 1200C 0.5 hrs
At 1500C 9 minutes

8. A process for the production of Magnesia Carbon refractory based composition /brick as claimed in claims 1 to 7 comprising the steps of :
(i) providing a pre-aged mix incorporating Amorphous Carbon Nano Tube (ACNT) in amounts of 0.05 -0.15 % by wt. selectively in magnesia based composition containing

SWM (Coarse) 74 – 87 % by wt.
SWM (Fines) 8 – 12 % by wt.
Aluminium powder 1.5 – 2.5 % by wt.
Graphite 4 – 6 % by wt.
Phenol-formaldehyde resin 4 – 5 % by wt.

(ii) subjecting the above pre-aged mix to aging for 16-24 hours to obtained aged green mixture ; and finally
(iii) shaping the aged refractory composition followed by its drying/curing.

9. A process for the production of Magnesia Carbon refractory brick as claimed in anyone of claims 2 to 8 comprising the steps of
A. Premixing (Wet) of all Amorphous Carbon Nano Tube (ACNT) and all Phenol-formaldehyde resin with about 1:1 (by volume) ethanol by applying ultrasonic vibration for 1 hour and cooling of premix below 250C.
B. Dry mixing of all the coarse grains (0.5mm to 4.5mm) taken together in a mixture for 5 to 7 minutes.
C. Addition of 50% (by weight) premixed liquid obtained in step ‘A’ to the dry mix.
D. Thereafter wet mixing for 5 to 7 minutes.
E. Addition of all the graphite (<0.5mm) to the resultant mix and then mixing for 5 to 7 minutes.
F. Addition of rest 50% of the premixed liquid obtained in step ‘A’ and rest of the fines (<0.074mm) to the resultant mix and then final mixing for 12 to 15 minutes to get the pre-aged mixture.
G. Aging of pre-aged mixture for 16-24 hours to get aged green mixture.
H. Pressing of aged green mix thus obtained by applying pressure of 1.8-2T/cm2 using required mould for different shapes; and
I. Subjecting the green bricks thus obtained obtained to dry/cure such as to thereby obtain there from the said Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick having high corrosion resistance and good thermo-mechanical behaviour.
10. A process as claimed in claim 9 comprising the steps of
(i) Oven/tunnel drier drying/curing of the green pressed body obtained in step (H) at 2500C for 24-32 hours maintaining desired rate of heating to obtain Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick with high corrosion resistance and good thermo-mechanical behaviour.

11. A process as claimed in anyone of claims 8 or 9 wherein said mixing/addition sequence of raw material ingredients comprising
(i) Premixing (Wet) of all Amorphous Carbon Nano Tube (ACNT) and all Phenol-formaldehyde resin with about 1:1 (by volume) ethanol by applying ultrasonic vibration for 1 hour and cooling of premix below 250C.

(ii) Dry mixing of all the coarse grains (0.5mm to 4.5mm) taken together in a mixture for 5 to 7 minutes.

(iii) Addition of 50% (by weight) premixed liquid obtained in step ‘(i)’ to the dry mix.

(iv) Thereafter wet mixing for 5 to 7 minutes.

(v) Addition of all the graphite (<0.5mm) to the resultant mix and then mixing for 5 to 7 minutes.

(vi) Addition of rest 50% of the premixed liquid obtained in step ‘A’ and rest of the fines (<0.074mm) to the resultant mix and then final mixing for 12 to 15 minutes to get the pre-aged mixture.

(vii) Aging of pre-aged mixture for 16-24 hours to get aged green mixture.

12. A process as claimed in anyone of claims 8 to 11 wherein said drying/curing process of green pressed body comprises

(i) In an oven/tunnel drier, green pressed body is placed.
(ii) Preheating of green pressed body at a rate of 0.5 to 0.60C per minute from ambient temperature to 1500C.
(iii) Heating up of green pressed body at 1 to 20C per minute from 150 to 2500C.
(iv) Allowing soaking time for 24 to 32 hours at the highest temperature to obtain green pressed body with required properties.

Dated this the 2nd day of September, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

, Description:FIELD OF THE INVENTION
The present invention relates to Magnesia Carbon refractory brick incorporated with Amorphous Carbon Nano Tube (ACNT). More particularly, the present invention is directed to provide a Magnesia Carbon refractory brick having high corrosion resistance and good thermo-mechanical behaviour by incorporating Amorphous Carbon Nano Tube (ACNT) in composition which is suitable for use in steel industry and a method of manufacturing said Magnesia Carbon refractory brick.
BACKGROUND OF THE INVENTION
Refractories are non-metallic inorganic materials, they have high softening temperature. They also possess good mechanical properties particularly at high temperatures and most often at room temperature as well, good stability on rapid temperature change etc. The materials also have good corrosion and erosion resistance to molten slag, metals and hot gases. Refractories show good mechanical properties at high temperature and as well as at low temperature. They have better corrosion and erosion resistance to molten slag, metals and hot gases. Due to good thermo-mechanical and thermo-chemical properties refractory materials are used in various high temperature processes, including iron and steel making, non-ferrous metal processing, cement, glass, chemical industries, in high temperature furnaces, kilns, boilers and incinerators.
MgO-C bricks by virtue of its unique combination of excellent mechanical, thermal and chemical properties are well established as high performing refractory products for application in Steel ladles. The use of graphite as a carbon source has many advantages in refractory applications. It has a high melting point and promotes the improvement of the corrosion resistance of the refractory, mainly due to its lower wettability by metal and slag. Thermal shock resistance of the refractory is improved due to the low thermal expansion, high thermal conductivity, and low modulus of elasticity promoted by the graphite addition. But, these composites have a few disadvantages, such as oxidation of graphite due to which decarburized layers eventually become susceptible to slag corrosion. In the last decade, the composition of MgO-C carbon refractories has been improved continuously mainly in area of purity of input materials, type of binders and additives for betterment of slag resistance, thermo-mechanical properties and oxidation resistance.

Many of the scientific and technological developments would not have been possible without refractory materials. Manufacturing of any metal without the use of refractory is impossible. Refractories consumption in steel and iron industries is nearly 70% of total refractories production. Iron and steel industries are the highest consumers of refractories. So, the refractory production has to be in sync with the demand of iron and steel industries. Better manufacturing and application environment is challenging a new generation of refractory material with improved properties, performance and life with eco-friendliness.
However, in recent years, stringent quality requirement for manufacturing of cleaner steel demands quantum jump in performance of refractory lining. In fact, refractory technology has long been considered to be almost mature and stagnant. If further leap forward of technology is aimed at, introduction of new technology which exceeds the ex¬isting frame of development is necessary. Realization of nanotech-refractories through engineering nano struc¬tural matrix is expected to be a path-breaking developmental effort. The use of highly reactive nano particles open up a vast range of possibilities of better reaction sintering in matrix phase formation through in situ reactions. A variety of nanoscale materials are already being used or have the potential to be used in MgO-C products for improving oxidation and slag resistance. Some of these include nanoscale carbon black (pure elemental carbon in the form of nanoscale particles with a semi-amorphous molecular structure), carbon nano tubes and other nanoscale additives particularly antioxidants such as, Al, Si, Mg-Al, B4C etc.
RDCIS has been working for development and application of new generation Magnesia Carbon refractory brick for Iron and Steel industries. A comprehensive laboratory based study was done for development of amorphous CNT incorporated Magnesia Carbon refractory brick with the potential of improving lining life under severe corrosive environment.

OBJECTS OF THE INVENTION
The basic object of the present invention is directed to provide Magnesia Carbon refractory composition/brick incorporate with Amorphous Carbon Nano Tube (ACNT) ensuring high corrosion resistance and better thermo-mechanical behaviour of such bricks to make them suitable for use in steel industry and a process for its production.
Another objective of the present invention is directed to incorporation of phenol-formaldehyde resin system compatible ACNT in Magnesia Carbon refractory brick.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to provide Magnesia carbon based refractory composition comprising:

Sea Water Magnesia (SWM) (Coarse) 74 – 87 % by wt.
Sea Water Magnesia (SWM) (Fines) 8 – 12 % by wt.
Aluminium powder 1.5 – 2.5 % by wt.
Graphite 4 – 6 % by wt.
Amorphous Carbon Nano Tube (ACNT) 0.05 – 0.15 % by wt.
Phenol-formaldehyde resin 4 – 5 % by wt.

A further aspect of the present invention is directed to provide Magnesia carbon based refractory composition which is magnesia carbon based refractory brick composition comprising:

Sea Water Magnesia (SWM) (Coarse) having particle size ranging from 3mm to 4.5 mm and about 23-28 % by weight,

Sea Water Magnesia (SWM) (Coarse) having particle size ranging from 1 mm to 3mm and about 28-31 % by weight,

Sea Water Magnesia (SWM) (Coarse) having particle size ranging from 0.5mm to 1 mm and about 23-28 % by weight,

Sea Water Magnesia (SWM) (Fines) having particle size below 0.044 mm and about 8-12 % by weight,

Aluminium powder (Fines) having particle size below 0.074 mm and about 1.5-2.5 % by weight,

Graphite having (Fines) having particle size below 0.5 mm and about 4-6 % by weight,

Amorphous Carbon Nano Tube (ACNT) (Fines) having diameter below 3x10-5 mm (30 nm) and about 0.05-0.15 % by weight,

Phenol-formaldehyde resin (Liquid) as binder having viscosity more than 250 cps at 250C and about 4-5 % by weight.

A still further aspect of the present invention is directed to provide Magnesia carbon based refractory composition/bricks wherein said Sea Water Magnesia (SWM) comprises
MgO (Min.), % 97
CaO (Max.), % 2
SiO2 (Max.), % 0.35
Fe2O3 (Max.), % 0.20
Al2O3 (Max), % 0.12
B2O3 (Max.), % 0.03
Avg. Crystal size (Min.), µ 100

A still further aspect of the present invention is directed to provide Magnesia carbon refractory composition/bricks wherein said Aluminium powder comprises
Al (Min.), % 99.5
Fe (Max.), % 0.40
Si (Max), % 0.15
Size (Max.), mm 0.74

A still further aspect of the present invention is directed to provide Magnesia carbon refractory composition/bricks wherein said Graphite comprising

Fixed Carbon (Min.), % 96
NGC (Max.), % 0.50
Volatile matter (Max), % 2.0
Moisture (Max.), % 0.50
Size Range
(+) 44 mesh BSS (Max.)
(-) 60mesh BSS (Min.)
(-) 72 mesh BSS (Min.)
(-) 100mesh BSS (Min.)
7.0
80
60
30

Another aspect of the present invention is directed to provide Magnesia carbon refractory composition/bricks wherein said Amorphous Carbon Nano Tube (ACNT) comprising
Purity (Min.), % 98
Outer diameter, nm 10 – 30
Length (Max), µm 15
Specific Surface area (Min.), m2/gm 200
Colour Black

Yet another aspect of the present invention is directed to provide Magnesia carbon refractory composition/bricks wherein said Phenol-formaldehyde Resin comprising
Type Resol
Non-volatile matter (%) 68-72
Fixed carbon (%) 35-40
Viscosity (cps), at 250C 250-300
Sp.Gravity at 200C 1.17-1.19
pH at 200C 6.5-7
Moisture Content (%) 8-10
Free Phenol (%) 14 (± 2)
Free Formaldehyde (%) 0.8 (± 0.2)
Shelf life (days) min 45
Water miscibility at 250C (Resin: water) 100:50 min
Ash content % (max) 0.2
Gel formation
At 800C 9 hrs
At 1000C 1.5hrs
At 1200C 0.5 hrs
At 1500C 9 minutes

A further aspect of the present invention is directed to a process for the production of Magnesia Carbon refractory based composition/brick as des cribbed above comprising the steps of :
(i) providing a pre-aged mix incorporating Amorphous Carbon Nano Tube (ACNT) in amounts of 0.05 -0.15 % by wt. selectively in magnesia based composition containing

SWM (Coarse) 74 – 87 % by wt.
SWM (Fines) 8 – 12 % by wt.
Aluminium powder 1.5 – 2.5 % by wt.
Graphite 4 – 6 % by wt.
Phenol-formaldehyde resin 4 – 5 % by wt.

(ii) subjecting the above pre-aged mix to aging for 16-24 hours to obtained aged green mixture ; and finally
(iii) shaping the aged refractory composition followed by its drying/curing.

Another aspect of the present invention is directed to said process for the production of Magnesia Carbon refractory brick comprising the steps of
A. Premixing (Wet) of all Amorphous Carbon Nano Tube (ACNT) and all Phenol-formaldehyde resin with about 1:1 (by volume) ethanol by applying ultrasonic vibration for 1 hour and cooling of premix below 250C.
B. Dry mixing of all the coarse grains (0.5mm to 4.5mm) taken together in a mixture for 5 to 7 minutes.
C. Addition of 50% (by weight) premixed liquid obtained in step ‘A’ to the dry mix.
D. Thereafter wet mixing for 5 to 7 minutes.
E. Addition of all the graphite (<0.5mm) to the resultant mix and then mixing for 5 to 7 minutes.
F. Addition of rest 50% of the premixed liquid obtained in step ‘A’ and rest of the fines (<0.074mm) to the resultant mix and then final mixing for 12 to 15 minutes to get the pre-aged mixture.
G. Aging of pre-aged mixture for 16-24 hours to get aged green mixture.
H. Pressing of aged green mix thus obtained by applying pressure of 1.8-2T/cm2 using required mould for different shapes; and
I. Subjecting the green bricks thus obtained obtained to dry/cure such as to thereby obtain there from the said Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick having high corrosion resistance and good thermo-mechanical behaviour.
Yet another aspect of the present invention is directed to said process comprising the steps of:
(i) Oven/tunnel drier drying/curing of the green pressed body obtained in step (H) at 2500C for 24-32 hours maintaining desired rate of heating to obtain Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick with high corrosion resistance and good thermo-mechanical behaviour.

A further aspect of the present invention is directed to said process wherein said mixing/addition sequence of raw material ingredients comprising
(i) Premixing (Wet) of all Amorphous Carbon Nano Tube (ACNT) and all Phenol-formaldehyde resin with about 1:1 (by volume) ethanol by applying ultrasonic vibration for 1 hour and cooling of premix below 250C.

(ii) Dry mixing of all the coarse grains (0.5mm to 4.5mm) taken together in a mixture for 5 to 7 minutes.

(iii) Addition of 50% (by weight) premixed liquid obtained in step ‘(i)’ to the dry mix.

(iv) Thereafter wet mixing for 5 to 7 minutes.

(v) Addition of all the graphite (<0.5mm) to the resultant mix and then mixing for 5 to 7 minutes.

(vi) Addition of rest 50% of the premixed liquid obtained in step ‘A’ and rest of the fines (<0.074mm) to the resultant mix and then final mixing for 12 to 15 minutes to get the pre-aged mixture.

(vii) Aging of pre-aged mixture for 16-24 hours to get aged green mixture.

A still further aspect of the present invention is directed to said process wherein said drying/curing process of green pressed body comprises

(i) In an oven/tunnel drier, green pressed body is placed.
(ii) Preheating of green pressed body at a rate of 0.5 to 0.60C per minute from ambient temperature to 1500C.
(iii) Heating up of green pressed body at 1 to 20C per minute from 150 to 2500C.
(iv) Allowing soaking time for 24 to 32 hours at the highest temperature to obtain green pressed body with required properties.

The objectives and advantages of the present invention are described hereunder in greater details with reference to the following accompanying illustrative example.

DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to provide Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick with high corrosion resistance and good thermo-mechanical behaviour suitable for use in steel industry and in particular related to process of manufacturing such Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick and development of its formulation. The batch composition of the Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick and its method of production is illustrated with following example:

Example:
In manufacturing of improved crystalline Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick according to the present invention, a base composition of Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick is developed. A pre-mix was prepared containing Amorphous Carbon Nano Tube (ACNT), liquid Phenol-formaldehyde resin and about 1:1 (by volume) ethanol by applying ultrasonic vibration for 1 hour and cooling of premix below 250C. All the coarse grains (0.5mm to 4.5mm) are taken in appropriate proportions and dry mix it in a mixer for 5 to 7 minutes. Then additions of 50% (by weight) premixed liquid to the dry mix and mix it for another 5 to 7 minutes. Then addition of all the graphite (<0.5mm) into the resultant mix and mixing for 5 to 7 minutes. Again, addition of rest 50% of the premixed liquid and rest of the fines (<0.074mm) to the resultant mix and then final mixing for 12 to 15 minutes. After sufficient mixing, mix taken out and keep for aging for 16 to 24 hours. Then Pressing of aged green mix thus obtained by applying pressure of 1.8-2T/cm2 using required mould for different shapes. All green pressed bodies are Oven/tunnel drier dryed/cured at 2500C for 24-32 hours. Considering the composition and granulometry of the developed formulation of the Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick, following drying/curing process is followed:

(i) In an oven/tunnel drier, green pressed body is placed.

(ii) Preheating of green pressed body at a rate of 0.5 to 0.60C per minute from ambient temperature to 1500C.

(iii) Heating up of green pressed body at 1 to 20C per minute from 150 to 2500C.

(iv) Allowing soaking time for 24 to 32 hours at the highest temperature to obtain green pressed body with required properties.

Batch Composition of invented Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick for use in steel industry
The present invention is directed to provide Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick with higher corrosion resistance and good thermo-mechanical behaviour for use in steel industry. The starting batch composition for producing such bricks is given in Annexure-I:
Annexure I : Batch Composition of Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick

Raw Material % (By Weight)
SWM (Coarse) 74 – 87
SWM (Fines) 8 – 12
Aluminium powder 1.5 – 2.5
Graphite 4 – 6
Amorphous Carbon Nano Tube (ACNT) 0.05 – 0.15
Phenol-formaldehyde resin 4 – 5

Details of different components of raw materials in a batch have been given in following Annexure II.

Annexure II: Details of different Raw Materials, Additives and Binder

Sea Water Magnesia (SWM)
MgO (Min.), % 97
CaO (Max.), % 2
SiO2 (Max.), % 0.35
Fe2O3 (Max.), % 0.20
Al2O3 (Max), % 0.12
B2O3 (Max.), % 0.03
Avg. Crystal size (Min.), µ 100

Aluminium Powder
Al (Min.), % 99.5
Fe (Max.), % 0.40
Si (Max), % 0.15
Size (Max.), mm 0.074

Graphite
Fixed Carbon (Min.), % 96
NGC (Max.), % 0.50
Volatile matter (Max), % 2.0
Moisture (Max.), % 0.50
Size Range
(+) 44 mesh BSS (Max.)
(-) 60mesh BSS (Min.)
(-) 72 mesh BSS (Min.)
(-) 100mesh BSS (Min.)
7.0
80
60
30

Amorphous Carbon Nano Tube (ACNT)
Purity (Min.), % 98
Outer diameter, nm 10 – 30
Length (Max), µm 15
Specific Surface area (Min.), m2/gm 200
Colour Black

Phenol-formaldehyde resin

Type Resol
Non-volatile matter (%) 68-72
Fixed carbon (%) 35-40
Viscosity (cps), at 250C 250-300
Sp.Gravity at 200C 1.17-1.19
pH at 200C 6.5-7
Moisture Content (%) 8-10
Free Phenol (%) 14 (± 2)
Free Formaldehyde (%) 0.8 (± 0.2)
Shelf life (days) min 45
Water miscibility at 250C (Resin: water) 100:50 min
Ash content % (max) 0.2
Gel formation
At 800C 9 hrs
At 1000C 1.5hrs
At 1200C 0.5 hrs
At 1500C 9 minutes

Further aspect of the present invention is that the above components are added and mixed in the order as indicated in Annexure III. The Properties of developed brick are given in Annexure IV.
Annexure III : Mixing sequence of ingredients
1. Premixing (Wet) of all Amorphous Carbon Nano Tube (ACNT) and all Phenol-formaldehyde resin with about 1:1 (by volume) ethanol by applying ultrasonic vibration for 1 hour and cooling of premix below 250C.
2. Dry mixing of all the coarse grains (0.5mm to 4.5mm) taken together in a mixture for 5 to 7 minutes.
3. Addition of 50% (by weight) premixed liquid obtained in step ‘(1)’ to the dry mix.
4. Thereafter wet mixing for 5 to 7 minutes.
5. Addition of all the graphite (<0.5mm) to the resultant mix and then mixing for 5 to 7 minutes.
6. Addition of rest 50% of the premixed liquid obtained in step ‘A’ and rest of the fines (<0.074mm) to the resultant mix and then final mixing for 12 to 15 minutes to get the pre-aged mixture.
7. Aging of pre-aged mixture for 16-24 hours to get aged green mixture.
Annexure IV:
Properties of Developed Amorphous Carbon Nano Tube (ACNT) incorporated Magnesia Carbon refractory brick
Properties Value
MgO (%),Min. 85
SiO2 (%),Max. 0.3
Fe2O3 (%),Max. 0.3
Bulk Density (B.D.) (gm/cc),Min., After curing at 2500C for 24 – 32 hours,(IS–1528, Part–XII) 3.00
Apparent Porosity (A.P.) (%),Max., After curing at 2500C for 24 – 32 hours,(IS–1528, Part–VIII) 7
Cold Compressive Strength (C.C.S.) (kg/cm2),Min. After curing at 2500C for 24 – 32 hours, (IS–1528, Part–IV) 500
Hot Modulus Of Rupture (HMOR) (kg/cm2),Min.,
After heating at 14000C for 0.5 hour (IS–1528, Part–XX) 55
Corrosion resistance index,Min.,
After firing with ladle slag at 15000C for 2 hours in oxidizing atmosphere 90
Oxidation resistance, (% weight loss),Max.,
After firing at 10000C for 3 hours in oxidizing atmosphere 4.5

Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.