Title of Invention	AN IMPROVED PROCESS FOR THE PRODUCTION OF BLENDED CEMENT CONTAINING HIGHER PROPORTION OF FLY ASH USING HIGH-ENERGY MILLING
Abstract	The present invention relates to an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling. The invention particularly relates to a process for the production of Portland pozzolana cement using cement clinker and higher proportion of fly ash, which is a waste material generated from thermal power plants. Novelty of the present invention is that it uses fly ash, which is an industrial waste, in the range of 25 -75% by weight. Also the products produced by the process of present invention have better early compressive strength (1 day 1-10 MPa, 3 day 10-20 MPa) that the products produced by conventional processes (1 day 1-5 MPa, 3 day 5-16 MPa)

Title of Invention

AN IMPROVED PROCESS FOR THE PRODUCTION OF BLENDED CEMENT CONTAINING HIGHER PROPORTION OF FLY ASH USING HIGH-ENERGY MILLING

Abstract

Full Text	The present invention relates to an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling. The invention particularly relates to a process for the production of Portland pozzolana cement using cement clinker and higher proportion of fly ash, which is a waste material generated from thermal power plants. The products produced by the process of present invention may be of different particle sizes and shapes, different specific surface areas and with different reactivity. The Portland pozzolana cement of the present invention shall be useful in buildings and other large structure such as dams, bridges, roads, etc. The hitherto known processes to produce Portland pozzolana cement use cement clinker, fly ash and gypsum. The existing possesses use cement clinker in the range of 70-90% by weight, fly ash in the range of 5-25% by weight and gypsum in the range of 1 to 5% by weight. The existing process to produce cement clinker which is the main raw material for Portland pozzolana cement consisted of crushing of raw materials such as limestone, clay, quartz, quartzite etc in a jaw crusher, fine grinding of the crushed raw material in a ball mill or vertical roller mill, proportioning of raw materials, blending in the silos and firing in the coal fired rotary kiln. The existing processes (A. K. Chatterjee, Availability and use of pozzolanic and cementitious solid wastes in India, Proceedings International Symposium on Concrete Technology for Sustainable development in the 21st Century, CMA, New Delhi, 1999) to produce Portland pozzolana cement consisted of inter-grinding of cement clinker, fly ash and gypsum for 30 to 60 minutes in a mill. Air is circulated in the mills for homogeneous grinding. The product obtained after grinding is Portland pozzolana cement. Traditionally, Portland pozzolana cement has been produced by inter-grinding cement clinker with fly ash in grinding mills (A. K. Chatterjee, Availability and use of pozzolanic and cementitious solid wastes in India, Proceedings International Symposium on Concrete Technology for Sustainable development in the 21st Century, CMA, New Delhi, 1999). Reference may be made to International patent No PCT/SE2003/001009, wherein the carbon dioxide emissions were reduced by using fly ash. The method and composition for manufacturing Portland pozzolana cement containing fly ash was patented in India in 1999 (1421/DEL/99). Reference may be made to R.A.Helmuth, Fly ash in cement and concrete, PCA, Skokie III, 1997, wherein the Portland pozzolana cement produced by existing processes have lower early strength and longer setting time than the ordinary Portland cement and this restricts the use of large proportion of fly ash in blended cement. Reference may be made to V. M. Malhotra, Advances in Concrete Technology, 2nd Edison, CANMET, Natural Resources Canada Publications, Ottawa, 1994, wherein uses of large volume of fly ash in blended cements have attracted intensive research attention. Fine grinding blended cement constituents, namely the clinker and the fly ash was suggested to improve the reactivity and use of high volume fly ash in cement (N. Bouzoubaa et al, Laboratory produced high volume fly ash blended cements: Physical properties and compressive strength of mortars, Cem Concr. Res., Vol 28, No. 11, 1998, 1555-69). Due to increased fineness, the controlled particle size distribution (CPSD) compensates for the relatively low hydraulic activity of fly ash. Reference may be made to S. Nagataki, E. Sakai and T. Takeuchi, The fluidity of fly ash-cement paste with superplasticizer. Cem. Concr. Res. 14 5 (1984), pp. 631-638, wherein fly ash with different particle size distributions changed the packing density and fluidity of the cement pastes. Reference may be made to J. Paya et al "Mechanical treatment of fly ashes: Prticle morphology of ground fly ash and workability of GFA-cement mortars, Cem. Concr. Res., Vol 26, No. 2, 1996, 225-35,, wherein the workability of Portland pozzolana cement was improved when fly ash ball-milled for different period was used in cement. According to literature and patent survey and available information, it may be mentioned that at present no process is available to produce Portland pozzolana cement using mechanical activation. The purpose of this development is to use abundantly available waste materials such as fly ash, which is causing environmental pollution, as major constituent to produce value added product such as Portland pozzolana cement. The hitherto known process have the following limitations: a. The main raw material for the Portland pozzolana cement is the cement clinker (70 to 90% by weight). Fly ash can be used only in the range of 5 to 25% by weight. The formation of cement clinker is an energy intensive process due to crushing, grinding and high temperature firing. Production of 1 ton of clinker consumes -3200 MJ energy. b. The formation of cement clinker includes high temperature firing and uses limestone (CaCO3) resulting into huge emission of CO2. Production of 1 ton of clinker emits ~1 ton CO2. c. The production cost of Portland pozzolana cement is relatively high as it uses more cement clinker. d. The early strength development is low due to poor reactivity of fly ash. The main object of the present investigation is to provide an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling, which obviates the drawbacks as detailed above. Another object of the present invention is to provide an improved process to produce Portland pozzolana cement using higher proportion (25 to 75% by weight) of industrial waste such as fly ash in place of cement clinker whereby the energy consumption is significantly reduced. Yet another object of the present invention is to provide an improved process to produce Portland pozzolana cement whereby the CO2 emission is significantly reduced. Still yet another object of the present invention is to provide an improved process to produce Portland pozzolana cement whereby the cost of production is appreciably lowered and the properties of the product is improved. Still yet another object of the present invention is to provide an improved process to produce Portland pozzolana cement whereby the reactivity of fly ash is increased by mechanical activation and the early strength development of the product is improved. The fly ash used in the present invention contains silica (SiO2), alumina (A^Os) and iron oxide (Fe2O3), and crystalline as well as amorphous in nature. The cement clinker used in present invention contains CaS, C2S, CsA and C4AF phases (C = CaO, S = SiO2, A = AbOs, F = Fe2Os). The gypsum used contains calcium oxide (CaO), sulphate (SOs) and water. In the Portland pozzolana cement produced by existing processes, fly ash is used as pozzolanic material i.e. it reacts with CaO of clinker during the hydration and gives cementitious properties. But fly ash does not actively participate in the hydration reaction during early stage due to its poor pozzolanic reactivity. As a result, the early strength development is very low. Thus only a limited quantity of fly ash is used in Portland pozzolana cement due to its poor pozzolanic reactivity. In the process of the present invention, the cement clinker is ball-milled separately in the dry condition. The fly ash is milled in high-energy milling devices such as an attrition mill or a vibratory mill. In attrition mill, smaller size (2 mm to Accordingly, the present invention provides an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling, which comprises: (i) ball-milling of cement clinker for a period ranging between 30 to 60 minutes in dry condition, (ii) high-energy milling of fly ash for a period ranging between 5 to 15 minutes in an attrition mill using fly ash to water ratio in the range of 1: 1 to 1:2 and fly ash to grinding ball ratio in the range of 1:5 to 1:15, or dry milling of fly ash for 15-30 minutes in a vibration mill, (iii) removing water from the slurry obtained after attrition milling by known process and drying thereafter, (iv) mixing intimately of: high-energy milled fly ash in the range of : 25 to 75% by weight ball-milled clinker in the range of : 25 to 75 % by weight gypsum in the range of : 01 to 05% by weight for a period in the range of 10 to 15 minutes. According to the feature of the invention, the fly ash, cement clinker and gypsum may be selected from the following composition range (Table Removed) The Portland pozzolana cement obtained in the present invention may have the following range of properties: (a) Compressive strength : Iday :l-10MPa 3 day :10-20MPa 7 day :15-25MPa 28 day : 30-50 MPa (b) Setting time Initial setting : 10-60 Minute Final setting :400-800 Minute (c) Autoclave expansion : Novelty of the present invention is that it uses fly ash, which is an industrial waste, in the range of 25 -75% by weight. Also the products produced by the process of present invention have better early compressive strength (1 day 1-10 MPa, 3 day 10-20 MPa) that the products produced by conventional processes (1 day 1-5 MPa, 3 day 5-16 MPa) The following examples are given by way of illustration and should not be construed to limit the scope of invention. EXAMPLE -1 600 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 350 grams of fly ash was wet milled in an attrition mill for 10 minutes using water as medium. The material to water ratio was kept as 1:1.5 and material to ball ratio was kept 1:10. The water present in attrition milled slurry was separated by filtering and then the material was dried at 40°C in an electric oven for 6 hours and then cooled to room temperature. 600 grams of ball-milled cement clinker, 350 grams of attrition milled dry powder of fly ash and 50 grams of gypsum powder were intimately mixed in a pot mill for 10 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 1. (Table Removed)EXAMPLE - 2 350 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 600 grams of fly ash was wet milled in an attrition mill for 15 minutes using water as medium. The material to water ratio was kept as 1:1.5 and material to ball ratio was kept 1:10. The water present in attrition milled slurry was separated by filtering and then the material was dried at 40°C in an electric oven for 6 hours and then cooled to room temperature. 350 grams of ball milled cement clinker, 600 grams of attrition milled dry powder of fly ash and 50 grams of gypsum powder were intimately mixed in a pot mill for 15 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 2. (Table Removed)500 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 450 grams of fly ash was dry milled in a vibration mill for 20 minutes. 500 grams of ball milled cement clinker, 450 grams of attrition milled dry powder of fly ash and 50 grams of gypsum powder were intimately mixed in a pot mill for 10 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 3.(Table Removed) EXAMPLE-4 220 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 750 grams of fly ash was dry milled in a vibration mill for 30 minutes. 220 grams of ball milled cement clinker, 750 grams of vibration milled dry powder of fly ash and 30 grams of gypsum powder were intimately mixed in a pot mill for 15 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 4. (Table Removed)The main advantages of the present invention are: 1. The process utilises higher proportion of abundantly available industrial waste (fly ash) as major raw material to produce Portland pozzolana cement, thereby the cost of production is considerably reduced in comparison to the known process. 2. The process of the present invention is helpful in resource conservation by replacing cement clinker, which uses costly raw materials e.g. limestone, clay, quartz, quartzite, etc for its production by an industrial wastes. 3. The process replaces high proportion of cement clinker, which is produced by an energy intensive process by an industrial waste (fly ash), thereby considerable reduction in energy consumption in comparison to the known process. 4. The process replaces high proportion of cement clinker, which causes CC>2 emission in the environment, by an industrial waste (fly ash), thereby considerable reduction in CC2 emission in comparison to the known process, 5. The products developed by the process of present invention are superior in terms of early strength development then the products produced by the existing process. This is obtained by the mechanical activation of fly ash, which enhances its pozzolanic reactivity and gives improved early strength. We claim: 1. An improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling, which comprises: i ball-milling of cement clinker for a period ranging between 30 to 60 minutes in dry condition, ii high-energy milling of fly ash.for a period ranging between 5 to 15 minutes in an attrition mill using fly ash to water ratio in the range of 1: 1 to 1:2 and fly ash to grinding ball ratio in the range of 1:5 to 1:15, or dry milling of fly ash for 15-30 minutes in a vibration mill, iii removing water from the slurry obtained after attrition milling by known process and drying thereafter, iv mixing intimately of: high-energy milled fly ash in the range of : 25 to 75% by weight ball-milled clinker in the range of : 25 to 75 % by weight gypsum in the range of : 01 to 05% by weight for a period in the range of 10 to 15 minutes. 2. An improved process as claimed in claim 1, where in fly ash has the composition range: SiO2 - 50 to 65%, A12O3 - 20 to 30%, Fe2O3 - 0 to 5%, CaO - 0 to 4% and glass content >40%. 3. An improved process as claimed in claims 1 & 2, where in cement clinker has the composition range : SiO2 - 20 to 25%, A12O3 - 3 to 8%, Fe2O3 - 2 to 4%, CaO - 60 to 70%, MgO - 0 to 6%, MnO - 0 to 4%, SO3 4. An improved process as claimed in claims 1 to 3, where in gypsum has the composition range : CaO - 25 to 40%, SO3 - 30 to 60%.

Full Text

The present invention relates to an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling. The invention particularly relates to a process for the production of Portland pozzolana cement using cement clinker and higher proportion of fly ash, which is a waste material generated from thermal power plants.
The products produced by the process of present invention may be of different particle sizes and shapes, different specific surface areas and with different reactivity. The Portland pozzolana cement of the present invention shall be useful in buildings and other large structure such as dams, bridges, roads, etc. The hitherto known processes to produce Portland pozzolana cement use cement clinker, fly ash and gypsum. The existing possesses use cement clinker in the range of 70-90% by weight, fly ash in the range of 5-25% by weight and gypsum in the range of 1 to 5% by weight. The existing process to produce cement clinker which is the main raw material for Portland pozzolana cement consisted of crushing of raw materials such as limestone, clay, quartz, quartzite etc in a jaw crusher, fine grinding of the crushed raw material in a ball mill or vertical roller mill, proportioning of raw materials, blending in the silos and firing in the coal fired rotary kiln.
The existing processes (A. K. Chatterjee, Availability and use of pozzolanic and cementitious solid wastes in India, Proceedings International Symposium on Concrete Technology for Sustainable development in the 21st Century, CMA, New Delhi, 1999) to produce Portland pozzolana cement consisted of inter-grinding of cement clinker, fly ash and gypsum for 30 to 60 minutes in a mill. Air is circulated in the mills for homogeneous grinding. The product obtained after grinding is Portland pozzolana cement.
Traditionally, Portland pozzolana cement has been produced by inter-grinding cement clinker with fly ash in grinding mills (A. K. Chatterjee, Availability and use of pozzolanic and cementitious solid wastes in India, Proceedings International Symposium on Concrete Technology for Sustainable development in the 21st Century, CMA, New Delhi, 1999). Reference may be made to International patent No PCT/SE2003/001009, wherein the carbon dioxide emissions were reduced by using
fly ash. The method and composition for manufacturing Portland pozzolana cement containing fly ash was patented in India in 1999 (1421/DEL/99). Reference may be made to R.A.Helmuth, Fly ash in cement and concrete, PCA, Skokie III, 1997, wherein the Portland pozzolana cement produced by existing processes have lower early strength and longer setting time than the ordinary Portland cement and this restricts the use of large proportion of fly ash in blended cement. Reference may be made to V. M. Malhotra, Advances in Concrete Technology, 2nd Edison, CANMET, Natural Resources Canada Publications, Ottawa, 1994, wherein uses of large volume of fly ash in blended cements have attracted intensive research attention. Fine grinding blended cement constituents, namely the clinker and the fly ash was suggested to improve the reactivity and use of high volume fly ash in cement (N. Bouzoubaa et al, Laboratory produced high volume fly ash blended cements: Physical properties and compressive strength of mortars, Cem Concr. Res., Vol 28, No. 11, 1998, 1555-69). Due to increased fineness, the controlled particle size distribution (CPSD) compensates for the relatively low hydraulic activity of fly ash. Reference may be made to S. Nagataki, E. Sakai and T. Takeuchi, The fluidity of fly ash-cement paste with superplasticizer. Cem. Concr. Res. 14 5 (1984), pp. 631-638, wherein fly ash with different particle size distributions changed the packing density and fluidity of the cement pastes. Reference may be made to J. Paya et al "Mechanical treatment of fly ashes: Prticle morphology of ground fly ash and workability of GFA-cement mortars, Cem. Concr. Res., Vol 26, No. 2, 1996, 225-35,, wherein the workability of Portland pozzolana cement was improved when fly ash ball-milled for different period was used in cement. According to literature and patent survey and available information, it may be mentioned that at present no process is available to produce Portland pozzolana cement using mechanical activation. The purpose of this development is to use abundantly available waste materials such as fly ash, which is causing environmental pollution, as major constituent to produce value added product such as Portland pozzolana cement.
The hitherto known process have the following limitations:
a. The main raw material for the Portland pozzolana cement is the cement clinker (70 to 90% by weight). Fly ash can be used only in the range of 5 to 25% by weight. The formation of cement clinker is an energy intensive process due to
crushing, grinding and high temperature firing. Production of 1 ton of clinker consumes -3200 MJ energy.
b. The formation of cement clinker includes high temperature firing and uses
limestone (CaCO3) resulting into huge emission of CO2. Production of 1 ton of
clinker emits ~1 ton CO2.
c. The production cost of Portland pozzolana cement is relatively high as it uses
more cement clinker.
d. The early strength development is low due to poor reactivity of fly ash.
The main object of the present investigation is to provide an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling, which obviates the drawbacks as detailed above.
Another object of the present invention is to provide an improved process to produce Portland pozzolana cement using higher proportion (25 to 75% by weight) of industrial waste such as fly ash in place of cement clinker whereby the energy consumption is significantly reduced.
Yet another object of the present invention is to provide an improved process to produce Portland pozzolana cement whereby the CO2 emission is significantly reduced.
Still yet another object of the present invention is to provide an improved process to produce Portland pozzolana cement whereby the cost of production is appreciably lowered and the properties of the product is improved.
Still yet another object of the present invention is to provide an improved process to produce Portland pozzolana cement whereby the reactivity of fly ash is increased by mechanical activation and the early strength development of the product is improved.
The fly ash used in the present invention contains silica (SiO2), alumina (A^Os) and iron oxide (Fe2O3), and crystalline as well as amorphous in nature. The cement
clinker used in present invention contains CaS, C2S, CsA and C4AF phases (C = CaO, S = SiO2, A = AbOs, F = Fe2Os). The gypsum used contains calcium oxide (CaO), sulphate (SOs) and water.
In the Portland pozzolana cement produced by existing processes, fly ash is used as pozzolanic material i.e. it reacts with CaO of clinker during the hydration and gives cementitious properties. But fly ash does not actively participate in the hydration reaction during early stage due to its poor pozzolanic reactivity. As a result, the early strength development is very low. Thus only a limited quantity of fly ash is used in Portland pozzolana cement due to its poor pozzolanic reactivity. In the process of the present invention, the cement clinker is ball-milled separately in the dry condition. The fly ash is milled in high-energy milling devices such as an attrition mill or a vibratory mill. In attrition mill, smaller size (2 mm to Accordingly, the present invention provides an improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling, which comprises:
(i) ball-milling of cement clinker for a period ranging between 30 to 60 minutes in dry condition,
(ii) high-energy milling of fly ash for a period ranging between 5 to 15 minutes
in an attrition mill using fly ash to water ratio in the range of 1: 1 to 1:2 and
fly ash to grinding ball ratio in the range of 1:5 to 1:15, or dry milling of fly
ash for 15-30 minutes in a vibration mill,
(iii) removing water from the slurry obtained after attrition milling by known
process and drying thereafter, (iv) mixing intimately of:
high-energy milled fly ash in the range of : 25 to 75% by
weight
ball-milled clinker in the range of : 25 to 75 % by
weight
gypsum in the range of : 01 to 05% by
weight
for a period in the range of 10 to 15 minutes.
According to the feature of the invention, the fly ash, cement clinker and gypsum may be selected from the following composition range (Table Removed)
The Portland pozzolana cement obtained in the present invention may have the following range of properties:
(a) Compressive strength :
Iday :l-10MPa
3 day :10-20MPa
7 day :15-25MPa

28 day : 30-50 MPa
(b) Setting time
Initial setting : 10-60 Minute
Final setting :400-800 Minute
(c) Autoclave expansion : Novelty of the present invention is that it uses fly ash, which is an industrial waste, in the range of 25 -75% by weight. Also the products produced by the process of present invention have better early compressive strength (1 day 1-10 MPa, 3 day 10-20 MPa) that the products produced by conventional processes (1 day 1-5 MPa, 3 day 5-16 MPa)
The following examples are given by way of illustration and should not be construed to limit the scope of invention.
EXAMPLE -1
600 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 350 grams of fly ash was wet milled in an attrition mill for 10 minutes using water as medium. The material to water ratio was kept as 1:1.5 and material to ball ratio was kept 1:10. The water present in attrition milled slurry was separated by filtering and then the material was dried at 40°C in an electric oven for 6 hours and then cooled to room temperature. 600 grams of ball-milled cement clinker, 350 grams of attrition milled dry powder of fly ash and 50 grams of gypsum powder were intimately mixed in a pot mill for 10 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 1.
(Table Removed)EXAMPLE - 2
350 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 600 grams of fly ash was wet milled in an attrition mill for 15 minutes using water as medium. The material to water ratio was kept as 1:1.5 and material to ball ratio was kept 1:10. The water present in attrition milled slurry was separated by filtering and then the material was dried at 40°C in an electric oven for 6 hours and then cooled to room temperature. 350 grams of ball milled
cement clinker, 600 grams of attrition milled dry powder of fly ash and 50 grams of gypsum powder were intimately mixed in a pot mill for 15 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 2.
(Table Removed)500 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 450 grams of fly ash was dry milled in a vibration mill for 20 minutes. 500 grams of ball milled cement clinker, 450 grams of attrition milled dry powder of fly ash and 50 grams of gypsum powder were intimately mixed in a pot mill for 10 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 3.(Table Removed) EXAMPLE-4
220 grams of cement clinker was dry milled in a ball mill for 30 minutes. The material to ball ratio was kept 1:10. 750 grams of fly ash was dry milled in a vibration mill for 30 minutes. 220 grams of ball milled cement clinker, 750 grams of vibration milled dry powder of fly ash and 30 grams of gypsum powder were intimately mixed in a pot mill for 15 minutes and then stored in an airtight container for various tests. Physical testing such as setting time, compressive strength after 1, 3, 7 and 28 day hydration, autoclave expansion was carried out as per Indian standard IS 4031-1998. The properties obtained are furnished in table 4.
(Table Removed)The main advantages of the present invention are:
1. The process utilises higher proportion of abundantly available industrial waste
(fly ash) as major raw material to produce Portland pozzolana cement, thereby
the cost of production is considerably reduced in comparison to the known
process.
2. The process of the present invention is helpful in resource conservation by
replacing cement clinker, which uses costly raw materials e.g. limestone, clay,
quartz, quartzite, etc for its production by an industrial wastes.
3. The process replaces high proportion of cement clinker, which is produced by
an energy intensive process by an industrial waste (fly ash), thereby
considerable reduction in energy consumption in comparison to the known
process.
4. The process replaces high proportion of cement clinker, which causes CC>2
emission in the environment, by an industrial waste (fly ash), thereby
considerable reduction in CC2 emission in comparison to the known process,
5. The products developed by the process of present invention are superior in
terms of early strength development then the products produced by the
existing process. This is obtained by the mechanical activation of fly ash,
which enhances its pozzolanic reactivity and gives improved early strength.

We claim:
1. An improved process for the production of blended cement containing higher proportion of fly ash using high-energy milling, which comprises: i ball-milling of cement clinker for a period ranging between 30 to 60 minutes in dry condition,
ii high-energy milling of fly ash.for a period ranging between 5 to 15 minutes in an attrition mill using fly ash to water ratio in the range of 1: 1 to 1:2 and fly ash to grinding ball ratio in the range of 1:5 to 1:15, or dry milling of fly ash for 15-30 minutes in a vibration mill,
iii removing water from the slurry obtained after attrition milling by known process and drying thereafter, iv mixing intimately of:
high-energy milled fly ash in the range of : 25 to 75% by weight
ball-milled clinker in the range of : 25 to 75 % by weight
gypsum in the range of : 01 to 05% by weight
for a period in the range of 10 to 15 minutes.
2. An improved process as claimed in claim 1, where in fly ash has the composition
range: SiO2 - 50 to 65%, A12O3 - 20 to 30%, Fe2O3 - 0 to 5%, CaO - 0 to 4% and glass
content >40%.
3. An improved process as claimed in claims 1 & 2, where in cement clinker has the composition range : SiO2 - 20 to 25%, A12O3 - 3 to 8%, Fe2O3 - 2 to 4%, CaO - 60 to 70%, MgO - 0 to 6%, MnO - 0 to 4%, SO3
4. An improved process as claimed in claims 1 to 3, where in gypsum has the composition range : CaO - 25 to 40%, SO3 - 30 to 60%.

Documents:

644-DEL-2006-Abstract-(03-07-2012).pdf

644-del-2006-abstract.pdf

644-DEL-2006-Claims-(03-07-2012).pdf

644-del-2006-claims.pdf

644-DEL-2006-Correspondence Others-(03-07-2012).pdf

644-del-2006-Correspondence Others-(07-08-2012).pdf

644-del-2006-correspondence-others 1.pdf

644-del-2006-correspondence-others.pdf

644-del-2006-description (complete).pdf

644-del-2006-form-1.pdf

644-del-2006-form-18.pdf

644-del-2006-form-2.pdf

644-DEL-2006-Form-3-(03-07-2012).pdf

644-del-2006-form-3.pdf

644-del-2006-form-5.pdf

644-del-2006-Petition-137-(07-08-2012).pdf

« Previous Patent

Next Patent »

Patent Number

254099

Indian Patent Application Number

644/DEL/2006

PG Journal Number

38/2012

Publication Date

21-Sep-2012

Grant Date

19-Sep-2012

Date of Filing

10-Mar-2006

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	RAKESH KUMAR	NATIONAL METALLURGICAL LABORATORY, COUNCIL OF SCIENTIFIC&INDUSTRIAL RESEARCH, JAMSHEDPUR-831007,INDIA.
2	SANJAY KUMAR	NATIONAL METALLURGICAL LABORATORY, COUNCIL OF SCIENTIFIC&INDUSTRIAL RESEARCH, JAMSHEDPUR-831007,INDIA.
3	AMITAVA BANDOPADHYAY	NATIONAL METALLURGICAL LABORATORY, COUNCIL OF SCIENTIFIC&INDUSTRIAL RESEARCH, JAMSHEDPUR-831007,INDIA.
4	SURYA PRATAP MEHROTRA	NATIONAL METALLURGICAL LABORATORY, COUNCIL OF SCIENTIFIC&INDUSTRIAL RESEARCH, JAMSHEDPUR-831007,INDIA.

PCT International Classification Number

C04B 18/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA