Indian Patents. 277129:A DRY QUENCHING PROCESS FOR WHITE CEMENT CLINKER MANUFACTURING

Title of Invention	A DRY QUENCHING PROCESS FOR WHITE CEMENT CLINKER MANUFACTURING
Abstract	The invention relates to a process for the production of white cement using dry quenching system. The dry quenching system is based on utilizing inert gas stream to lower down the temperature of hot cement clinker.

Full Text	FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10; rule 13) A DRY QUENCHING PROCESS FOR WHITE CEMENT CLINKER MANUFACTURING GRASIM INDUSTRIES LIMITED. an Indian Company of Birlagram, Nagda - 456331, Madhya Pradesh, India. THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. FIELD OF INVENTION The present invention relates to a process for manufacturing white cement. Particularly, the present invention relates to a dry quenching process for manufacturing white cement clinker. BACKGROUND OF THE INVENTION The conventional manufacturing process for white cement, as shown in Figure 1, involves crushing of the raw materials primarily comprising a mixture of limestone (or calcareous material) and clay, typically kaolin (or argillaceous material) in a crusher. The crushed mixture is further sent to a raw mill for grinding. The fine mixture primarily containing limestone and kaolin is then calcined at a temperature of 1500 - 1550 deg C in a rotary kiln to chemically fuse the raw materials and produce a white cement clinker. The resulting white cement clinker thus formed in the rotary kiln is to be quenched with water to prevent the re-oxidation of the iron and thus maintain the whiteness of the cement clinker. The quenching process is done by passing the cement clinker through a quencher or a decoloriser/dryer , as shown in Figure 1, wherein in a reduced atmosphere the clinker temperature is rapidly lowered from 1200 deg C to below 600 deg C. Conventionally, a wet quenching process, as disclosed in Figure 1 & 2, is used which involves dropping the hot cement clinker in cold water. Referring to Figure 2 of the accompanying drawings, red hot clinker from the rotary kiln having a temperature of above 1200 deg C are discharged in a decoloriser/quencher where water is added for quenching. During wet quenching by water, clinker is dried by super heated steam, dry white cement clinker having temperature below 200 deg C is formed and super heated steam along with flue gases and clinker dust is discharged. The super heated steam thus discharged has a temperature between 200 - 400 deg C and is laden with dust and gases. The exhaust gas stream comprising 55% steam and 45% air is passed through cyclone separators then through an electrostatic precipitator (ESP) or bag house to remove the dust particles and then released into the atmosphere. The temperature of the exhaust gas stream leaving the cyclone separator is in the range of 160 - 220 deg C. Referring to Figure 1, the white cement clinker from the decoloriser/dryer, after a drying stage, is ground to cement. The water used in the conventional wet quenching process for cooling the red hot white cement clinker, as disclosed in Figure 1, exchanges heat with the white cement clinker and is converted into steam having very high temperatures. This steam is eliminated along with the exhaust gases into the atmosphere through ESP/ bag House. The cement manufacturing process is already very energy-sensitive, in the conventional process large quantity of energy is lost as the thermal energy contained in the steam is discharged into the atmosphere unused. Also, large quantity of water is used in the wet quenching process, where water conservation in industries is becoming a very crucial issue. In the conventional process, as disclosed in Figure 1, dust particles and exhaust gases are emitted from the grinding, calcining, quenching and drying processes. These exhaust gases contain substantial quantity of dust particles which have detrimental heath and environmental impacts. The dust particles are to be removed by a cyclone separator and the gas stream must be further passed through an electrostatic precipitator /Bag House to remove the particulate matter before discharging into the atmosphere to comply by the pollution board discharge standards. Unlike the Portland Grey cement, the production of white cement clinker requires special care during quenching process, for avoiding any deterioration of the degree of the whiteness of the cement. As evidenced from the prior art, the quenching process involved in the production of white cement clinker generally comprises of using the water stream for rapidly lowering down the temperature of cement clinker from 1200 °C-1400 °C to approximately 600 °C, in a few seconds as it leaves the kiln. The conventional wet quenching processes as disclosed in Figure 1 suffers from number of drawbacks which include high particulate matter, wastage of energy and high usage of water. The dry cooling method for hot bulk materials is also one of the most widely used methods. The dry cooling method comprises of cooling the hot bulk materials with a stream of inert gas/gases in a closed circuit. However, most of the studies available on the dry cooling of hot bulk materials are related to coke. In comparison to the wet cooling processes, the dry cooling of the hot bulk materials provides substantial advantages to the environment and better recovery of energy. Therefore, there is felt a need for the development of white cement manufacturing process that overcomes the drawbacks of conventional process. OBJECTS OF THE INVENTION An object of the present invention is to provide a process for manufacturing white cement clinker. Another object of the present invention is to provide a dry quenching process for manufacturing white cement clinker. Yet another object of the present invention is to provide a process for manufacturing white cement clinker which conserves energy. Still another object of the present invention is to provide a process for manufacturing white cement clinker which conserves water. Still one more object of the present invention is to provide a process for manufacturing white cement clinker where wastage of energy is negligent. Yet one more object of the present invention is to provide a process for manufacturing white cement clinker which is cost effective. SUMMARY OF THE INVENTION In accordance with the present invention there is provided a process for the production of white cement clinker; said process comprises the following steps: a. crushing lime stone and clay through crusher stacker reclaimer and grinder to obtain fine particulate matter; b. blending the particulate matter to obtain blended particulate mass; c. heating the particulate mass in kiln at a temperature between 1450 °C to 1500 °C to obtain the hot cement clinker; d. quenching the hot cement clinker in a closed chamber with a inert gas stream to obtain white cement clinker and hot inert gas stream; e. extracting sensible heat from the hot inert gas stream; and f. grinding the decolorized cement clinker to obtain white cement. Typically, the inert gas comprises a single element or a mixture of inert gases. Typically, the mixture of inert gases is selected from the group consisting of nitrogen, argon, neon, helium, krypton, xenon and radon. Preferably, the preferred inert gas is a nitrogen gas. Typically, the hot cement clinker comprises the temperature of about 1200 °C. Typically, the quenching process lowers down the temperature of hot cement clinker in the range of 160 °C to 220 °C. Preferably, the quenching process lowers down the temperature of hot cement clinker below 200 °C. Typically, the hot inert gas stream comprises the temperature of about 500 °C to 800 °C. Typically, the sensible heat from the hot inert gas stream is extracted by passing said hot inert gas stream through waste heat recovery system. Typically, the quenching process conserves about 15 % to 30 % of the energy. Typically, the quenching process saves about 400 to 450 liters of water per ton of clinker. Typically, the quenching process provides the white cement comprising the whiteness of about 90 to 95 on hunter whiteness scale. Typically, the heat liberated per ton of cement clinker produced is in the range of 1,00,000 Kcal to 2,75,000 Kcal. BRIEF DESCRIPTION OF THE FIGURES The invention will now be briefly described in relation to the accompanying drawing, in which: Figure 1 illustrates a schematic diagram of the conventional process for manufacturing white cement; Figure 2 illustrates a schematic diagram showing the wet quenching process used in the conventional process for manufacturing white cement clinker; Figure 3 illustrates a schematic diagram of the white cement manufacturing process, in accordance with the present invention; and Figure 4 illustrates a schematic diagram of the dry quenching process used in the white cement clinker manufacturing process, in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration. In comparison to the ordinary grey Portland cement, the production of white cement is extremely complex and far more expensive because of lower product out put and more energy demand. The decisive factor for the whiteness of the cement is the cement clinker cooling/quenching process. Among commercially utilized methods for cooling of hot bulk materials, the dry cooling methods are more significant because of providing substantially better recovery of energy thereby making the process more energy efficient and cost effective. Accordingly, the present invention envisages a process for manufacturing white cement using a dry quenching system, as represented in Figure 3. The first step of the process for manufacturing white cement clinker of the present invention comprises of manufacturing the hot cement clinker by using conventional process. The process steps of crusing, grinding, bending and clinkering constitute the part of the conventional process. For the production of white cement clinker, the selection of raw materials is of great importance. The lime stones and clay (kaolin) containing negligible amount of iron, manganese oxide and the substances that give grey color to the cement are the most preferred materials for the production of white cement clinker. In accordance with the present invention as provided in Figure-3, the lime stones, clay and other useful ingredients are fed in Crusher Stacker Reclaimer independently to obtain the said materials in reduced size. After crushing, the crushed raw materials are proportioned and fed to Raw Meal Grinder to obtain the fine particulate matter. Afterward, the fine particulate materials are blended and fed in kiln, operating at a temperature of about 1450 °C to 1500 °C; at a high temperature condition, the blended fine particulate matter undergoes series of chemical reactions to obtain hot cement clinker. The hot cement clinker is then subjected to cooling/quenching process. In the production of white cement clinker, the cooling/quenching process is a very crucial step. In accordance with the present invention, there is provided a dry quenching process for the production of white cement clinker, as shown in Figure 4. The dry quenching process of the present invention comprises of circulating the dry inert gas through closed chamber containing red hot cement clinker. The purity of the inert gas also plays a very decisive role; hence the purity of the inert gases is maintained at highest level. The red hot white cement clinker from the rotary kiln having a temperature above 1200 °C are sent to decoloriser/dryer/quencher/closed chamber where the hot white cement clinker is dry quenched by passing inert gas in a closed environment, refer Figure 4. In order to complete the quenching process in a short period of time, quantity of the inert gas circulated through the closed chamber is also regulated. In accordance with one embodiment of the present invention, the inert gas used in the dry quenching system is a single element or a mixture of inert gases. In accordance with another embodiment of the present invention, the inert gas is at least one gas selected from the group consisting of nitrogen, argon, neon, helium, krypton, xenon and radon. In accordance with yet another embodiment of the present invention, the inert gas is nitrogen. The inert gas flowing through the closed chamber absorbs the heat from the hot white cement clinker, thus, cooling the hot clinker below temperature in the range of 160 °C to 220 °C. In accordance with one embodiment of the present invention, the hot cement clinker is cooled to a temperature below 200 °C. The inert gas stream circulated through the dry quenching system, as shown in Figure 4 of the present invention, gains heat from the red hot white cement clinker and becomes very hot having temperatures around 500 -800°C. In accordance with the present invention, as shown in Figure 3 & 4, the hot inert gas will be emitted from the decoloriser/dryer/quencher/closed chamber. The thermal energy released through the exhaust gas stream from the decoloriser/dryer/quencher/closed chamber of the dry quenching system is extracted through any waste heat recovery system. In accordance with the present invention, the hot inert gas stream is introduced into the waste heat recovery system where the sensible heat of the inert gas is recovered. By recovering the sensible heat contained in the red hot white cement clinker, the energy efficiency of the clinkerisation process is improved. The dry quenching system, of the present invention, reuses the thermal energy generated during dry quenching by the inert gas, thus conserving about 15 to 30% of the energy in comparison with the conventional wet quenching process, for the manufacture of white cement clinker thereby reducing Green house Gases . The heat liberated per ton of cement clinker produced is found to be in the range of 1,00,000 Kcal to 2,75,000 Kcal. Since, water is not used during the dry quenching process of the present invention; the dry quenching process is able to save around 400 to 450 liters of water per ton of clinker. In accordance to the present invention, referring to Figure 3, in the process for manufacturing white cement clinker using the dry quenching system of the present invention, the exhaust gases are emitted only from the grinding and the calcining processes The decolorized white cement clinker thus obtained by dry quenching process of the present invention is sent to Cement Grinder to obtain the white cement. The white cement is then subjected to chemical analysis and whiteness measurement. Whiteness of the white cement is the most important characteristic feature of white cement manufacturing process. The dry quenching system of the present invention provides a whiteness of about 90 -95 on hunter whiteness scale. TECHNICAL ADVANTAGES A process for manufacturing white cement clinker, as described in the present invention has several technical advantages including but not limited to the realization of: • a dry quenching process for manufacturing white cement clinker; • a process for manufacturing white cement clinker which conserves energy; • a process for manufacturing white cement clinker which conserves water; • a process for manufacturing white cement clinker where wastage of energy is negligent; and • a process for manufacturing white cement clinker which is cost effective. While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. The invention is further illustrated by way of the following non-limiting examples: Example-1: A scaled down vertical cylindrical cooling chamber was fabricated and assembled with a provision to blow inert gas from the bottom of the chamber. The inert gas was supplied through external storages. A solid object (combination of cone and cylinder) was placed inside the cylindrical chamber for proper distribution of inert gas. The solid object was placed over a screen which helped in the formation of bed & enhanced heat transfer between red hot clinker and inert gas. The purity of inert gas was maintained at highest level & quantity of inert gas was regulated. Red hot clinker from furnace made to fall inside the cooling chamber and kept inside the cooling. After cooling the cooled clinker was ground for chemical analysis & whiteness. Whiteness is the most important characteristic of white cement manufacturing. By this experiment of dry quenching could get whiteness of 90.1 on hunter whiteness scale. Contents Chemical Analysis Raw Mix typical Sample Dry Quenched Sample-1 Dry Quenched Sample-2 (%) (%) (%) Si02 15.1 24.47 24.85 A1203 3.5 5.12 5.15 Fe203 0.1 0.212 0.21 CaO 42.4 66.57 66.41 MgO 1.1 1.72 1.69 K20 0.6 0.08 0.08 CI 0 0.008 0.008 F 0.2 0.323 0.33 Lime Stone Factor 91 88.93 88.89 Silica Modulus 4.1 4.59 4.S9 Alunima Modulus 26.5 24.16 24.2 Whiteness (On Hunter whiteness scale) Not Applicable 90.02 90.1 Claims: We claim: 1. A process for the production of white cement clinker; said process comprises the following steps: a. crushing lime stone and clay through a crusher stacker reclaimer and grinder to obtain fine particulate matter; b. blending the particulate matter to obtain blended particulate mass; c. heating the particulate mass in a kiln at a temperature between 1450 °C to 1500 °C to obtain hot cement clinker; d. quenching the hot cement clinker in a closed chamber with a inert gas stream to obtain decolorized cement clinker and hot inert gas stream; e. extracting sensible heat from the hot inert gas stream for energy utilization; and f. grinding the decolorized cement clinker to obtain white cement. 2. The process as claimed in claim 1, wherein the inert gas comprises a single element or a mixture of inert gases. 3. The process as claimed in claim 2, wherein the inert gas is at least one gas selected from the group consisting of nitrogen, argon, neon, helium, krypton, xenon and radon. 4. The process as claimed in claim 2, wherein the preferred inert gas is nitrogen. 5. The process as claimed in claim 1, wherein the hot cement clinker entering the closed chamber at a temperature of about 1200 °C. 6. The process as claimed in claim 1, wherein the temperature of the hot cement clinker in the closed chamber lowers to the range of 160 °C to 220 °C. 7. The process as claimed in claim 6, wherein the quenching step lowers the temperature of hot cement clinker below 200 °C. 8. The process as claimed in claim 1, wherein the temperature of the hot inert gas stream emanating from the closed chamber is about 500 °C -800 °C. 9. The process as claimed in claim 1, wherein the sensible heat from the hot inert gas stream is extracted by passing said hot inert gas stream through a waste heat recovery system. 10. The process as claimed in claim 1, wherein the quenching process conserves about 15 % to 30 % of the energy. 11. The process as claimed in claim 1, wherein the quenching process saves about 400 to 450 liters of water per ton of clinker. 12. The process as claimed in claim 1, wherein the quenching process provides the white cement comprising whiteness of about 90-95 on a hunter whiteness scale. 13. The process as claimed in claim 1, wherein the heat liberated per ton of cement clinker produced is in the range of 1,00,000 Kcal to 2,75,000 Kcal.

Full Text

FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
A DRY QUENCHING PROCESS FOR WHITE CEMENT CLINKER MANUFACTURING
GRASIM INDUSTRIES LIMITED.
an Indian Company
of Birlagram, Nagda - 456331,
Madhya Pradesh, India.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to a process for manufacturing white cement.
Particularly, the present invention relates to a dry quenching process for manufacturing white cement clinker.
BACKGROUND OF THE INVENTION
The conventional manufacturing process for white cement, as shown in Figure 1, involves crushing of the raw materials primarily comprising a mixture of limestone (or calcareous material) and clay, typically kaolin (or argillaceous material) in a crusher. The crushed mixture is further sent to a raw mill for grinding. The fine mixture primarily containing limestone and kaolin is then calcined at a temperature of 1500 - 1550 deg C in a rotary kiln to chemically fuse the raw materials and produce a white cement clinker. The resulting white cement clinker thus formed in the rotary kiln is to be quenched with water to prevent the re-oxidation of the iron and thus maintain the whiteness of the cement clinker. The quenching process is done by passing the cement clinker through a quencher or a decoloriser/dryer , as shown in Figure 1, wherein in a reduced atmosphere the clinker temperature is rapidly lowered from 1200 deg C to below 600 deg C.
Conventionally, a wet quenching process, as disclosed in Figure 1 & 2, is used which involves dropping the hot cement clinker in cold water. Referring to Figure 2 of the accompanying drawings, red hot clinker from the rotary kiln having a temperature of above 1200 deg C are discharged in a decoloriser/quencher where water is added for quenching. During wet quenching by water, clinker is dried by super heated steam, dry white

cement clinker having temperature below 200 deg C is formed and super heated steam along with flue gases and clinker dust is discharged. The super heated steam thus discharged has a temperature between 200 - 400 deg C and is laden with dust and gases. The exhaust gas stream comprising 55% steam and 45% air is passed through cyclone separators then through an electrostatic precipitator (ESP) or bag house to remove the dust particles and then released into the atmosphere. The temperature of the exhaust gas stream leaving the cyclone separator is in the range of 160 - 220 deg C. Referring to Figure 1, the white cement clinker from the decoloriser/dryer, after a drying stage, is ground to cement.
The water used in the conventional wet quenching process for cooling the red hot white cement clinker, as disclosed in Figure 1, exchanges heat with the white cement clinker and is converted into steam having very high temperatures. This steam is eliminated along with the exhaust gases into the atmosphere through ESP/ bag House. The cement manufacturing process is already very energy-sensitive, in the conventional process large quantity of energy is lost as the thermal energy contained in the steam is discharged into the atmosphere unused. Also, large quantity of water is used in the wet quenching process, where water conservation in industries is becoming a very crucial issue.
In the conventional process, as disclosed in Figure 1, dust particles and exhaust gases are emitted from the grinding, calcining, quenching and drying processes. These exhaust gases contain substantial quantity of dust particles which have detrimental heath and environmental impacts. The dust particles are to be removed by a cyclone separator and the gas stream must

be further passed through an electrostatic precipitator /Bag House to remove the particulate matter before discharging into the atmosphere to comply by the pollution board discharge standards.
Unlike the Portland Grey cement, the production of white cement clinker requires special care during quenching process, for avoiding any deterioration of the degree of the whiteness of the cement. As evidenced from the prior art, the quenching process involved in the production of white cement clinker generally comprises of using the water stream for rapidly lowering down the temperature of cement clinker from 1200 °C-1400 °C to approximately 600 °C, in a few seconds as it leaves the kiln. The conventional wet quenching processes as disclosed in Figure 1 suffers from number of drawbacks which include high particulate matter, wastage of energy and high usage of water.
The dry cooling method for hot bulk materials is also one of the most widely used methods. The dry cooling method comprises of cooling the hot bulk materials with a stream of inert gas/gases in a closed circuit. However, most of the studies available on the dry cooling of hot bulk materials are related to coke. In comparison to the wet cooling processes, the dry cooling of the hot bulk materials provides substantial advantages to the environment and better recovery of energy.
Therefore, there is felt a need for the development of white cement manufacturing process that overcomes the drawbacks of conventional process.

OBJECTS OF THE INVENTION
An object of the present invention is to provide a process for manufacturing white cement clinker.
Another object of the present invention is to provide a dry quenching process for manufacturing white cement clinker.
Yet another object of the present invention is to provide a process for manufacturing white cement clinker which conserves energy.
Still another object of the present invention is to provide a process for manufacturing white cement clinker which conserves water.
Still one more object of the present invention is to provide a process for manufacturing white cement clinker where wastage of energy is negligent.
Yet one more object of the present invention is to provide a process for manufacturing white cement clinker which is cost effective.

SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a process for the production of white cement clinker; said process comprises the following steps:
a. crushing lime stone and clay through crusher stacker reclaimer and
grinder to obtain fine particulate matter;
b. blending the particulate matter to obtain blended particulate mass;
c. heating the particulate mass in kiln at a temperature between 1450
°C to 1500 °C to obtain the hot cement clinker;
d. quenching the hot cement clinker in a closed chamber with a inert
gas stream to obtain white cement clinker and hot inert gas
stream;
e. extracting sensible heat from the hot inert gas stream; and
f. grinding the decolorized cement clinker to obtain white cement.
Typically, the inert gas comprises a single element or a mixture of inert gases.
Typically, the mixture of inert gases is selected from the group consisting of nitrogen, argon, neon, helium, krypton, xenon and radon.
Preferably, the preferred inert gas is a nitrogen gas.
Typically, the hot cement clinker comprises the temperature of about 1200 °C.

Typically, the quenching process lowers down the temperature of hot cement clinker in the range of 160 °C to 220 °C.
Preferably, the quenching process lowers down the temperature of hot cement clinker below 200 °C.
Typically, the hot inert gas stream comprises the temperature of about 500 °C to 800 °C.
Typically, the sensible heat from the hot inert gas stream is extracted by passing said hot inert gas stream through waste heat recovery system.
Typically, the quenching process conserves about 15 % to 30 % of the energy.
Typically, the quenching process saves about 400 to 450 liters of water per ton of clinker.
Typically, the quenching process provides the white cement comprising the whiteness of about 90 to 95 on hunter whiteness scale.
Typically, the heat liberated per ton of cement clinker produced is in the range of 1,00,000 Kcal to 2,75,000 Kcal.

BRIEF DESCRIPTION OF THE FIGURES
The invention will now be briefly described in relation to the accompanying drawing, in which:
Figure 1 illustrates a schematic diagram of the conventional process for manufacturing white cement;
Figure 2 illustrates a schematic diagram showing the wet quenching process used in the conventional process for manufacturing white cement clinker;
Figure 3 illustrates a schematic diagram of the white cement manufacturing process, in accordance with the present invention; and
Figure 4 illustrates a schematic diagram of the dry quenching process used in the white cement clinker manufacturing process, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.
In comparison to the ordinary grey Portland cement, the production of white cement is extremely complex and far more expensive because of lower product out put and more energy demand. The decisive factor for the whiteness of the cement is the cement clinker cooling/quenching process. Among commercially utilized methods for cooling of hot bulk materials, the dry cooling methods are more significant because of providing substantially better recovery of energy thereby making the process more energy efficient and cost effective.
Accordingly, the present invention envisages a process for manufacturing white cement using a dry quenching system, as represented in Figure 3.
The first step of the process for manufacturing white cement clinker of the present invention comprises of manufacturing the hot cement clinker by using conventional process. The process steps of crusing, grinding, bending and clinkering constitute the part of the conventional process.
For the production of white cement clinker, the selection of raw materials is of great importance. The lime stones and clay (kaolin) containing negligible amount of iron, manganese oxide and the substances that give grey color to the cement are the most preferred materials for the production of white cement clinker.

In accordance with the present invention as provided in Figure-3, the lime stones, clay and other useful ingredients are fed in Crusher Stacker Reclaimer independently to obtain the said materials in reduced size.
After crushing, the crushed raw materials are proportioned and fed to Raw Meal Grinder to obtain the fine particulate matter. Afterward, the fine particulate materials are blended and fed in kiln, operating at a temperature of about 1450 °C to 1500 °C; at a high temperature condition, the blended fine particulate matter undergoes series of chemical reactions to obtain hot cement clinker.
The hot cement clinker is then subjected to cooling/quenching process. In the production of white cement clinker, the cooling/quenching process is a very crucial step.
In accordance with the present invention, there is provided a dry quenching process for the production of white cement clinker, as shown in Figure 4.
The dry quenching process of the present invention comprises of circulating the dry inert gas through closed chamber containing red hot cement clinker. The purity of the inert gas also plays a very decisive role; hence the purity of the inert gases is maintained at highest level.
The red hot white cement clinker from the rotary kiln having a temperature above 1200 °C are sent to decoloriser/dryer/quencher/closed chamber where the hot white cement clinker is dry quenched by passing inert gas in a closed

environment, refer Figure 4. In order to complete the quenching process in a short period of time, quantity of the inert gas circulated through the closed chamber is also regulated.
In accordance with one embodiment of the present invention, the inert gas used in the dry quenching system is a single element or a mixture of inert
gases.
In accordance with another embodiment of the present invention, the inert gas is at least one gas selected from the group consisting of nitrogen, argon, neon, helium, krypton, xenon and radon.
In accordance with yet another embodiment of the present invention, the inert gas is nitrogen.
The inert gas flowing through the closed chamber absorbs the heat from the hot white cement clinker, thus, cooling the hot clinker below temperature in the range of 160 °C to 220 °C.
In accordance with one embodiment of the present invention, the hot cement clinker is cooled to a temperature below 200 °C.
The inert gas stream circulated through the dry quenching system, as shown in Figure 4 of the present invention, gains heat from the red hot white cement clinker and becomes very hot having temperatures around 500 -800°C.

In accordance with the present invention, as shown in Figure 3 & 4, the hot inert gas will be emitted from the decoloriser/dryer/quencher/closed chamber. The thermal energy released through the exhaust gas stream from the decoloriser/dryer/quencher/closed chamber of the dry quenching system is extracted through any waste heat recovery system.
In accordance with the present invention, the hot inert gas stream is introduced into the waste heat recovery system where the sensible heat of the inert gas is recovered.
By recovering the sensible heat contained in the red hot white cement clinker, the energy efficiency of the clinkerisation process is improved.
The dry quenching system, of the present invention, reuses the thermal energy generated during dry quenching by the inert gas, thus conserving about 15 to 30% of the energy in comparison with the conventional wet quenching process, for the manufacture of white cement clinker thereby reducing Green house Gases . The heat liberated per ton of cement clinker produced is found to be in the range of 1,00,000 Kcal to 2,75,000 Kcal.
Since, water is not used during the dry quenching process of the present invention; the dry quenching process is able to save around 400 to 450 liters of water per ton of clinker.
In accordance to the present invention, referring to Figure 3, in the process for manufacturing white cement clinker using the dry quenching system of

the present invention, the exhaust gases are emitted only from the grinding and the calcining processes
The decolorized white cement clinker thus obtained by dry quenching process of the present invention is sent to Cement Grinder to obtain the white cement.
The white cement is then subjected to chemical analysis and whiteness measurement. Whiteness of the white cement is the most important characteristic feature of white cement manufacturing process. The dry quenching system of the present invention provides a whiteness of about 90 -95 on hunter whiteness scale.

TECHNICAL ADVANTAGES
A process for manufacturing white cement clinker, as described in the present invention has several technical advantages including but not limited to the realization of:
• a dry quenching process for manufacturing white cement clinker;
• a process for manufacturing white cement clinker which conserves energy;
• a process for manufacturing white cement clinker which conserves water;
• a process for manufacturing white cement clinker where wastage of energy is negligent; and
• a process for manufacturing white cement clinker which is cost effective.
While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

The invention is further illustrated by way of the following non-limiting examples:
Example-1:
A scaled down vertical cylindrical cooling chamber was fabricated and assembled with a provision to blow inert gas from the bottom of the chamber. The inert gas was supplied through external storages. A solid object (combination of cone and cylinder) was placed inside the cylindrical chamber for proper distribution of inert gas. The solid object was placed over a screen which helped in the formation of bed & enhanced heat transfer between red hot clinker and inert gas. The purity of inert gas was maintained at highest level & quantity of inert gas was regulated. Red hot clinker from furnace made to fall inside the cooling chamber and kept inside the cooling. After cooling the cooled clinker was ground for chemical analysis & whiteness. Whiteness is the most important characteristic of white cement manufacturing. By this experiment of dry quenching could get whiteness of 90.1 on hunter whiteness scale.

Contents Chemical Analysis

Raw Mix typical Sample Dry Quenched
Sample-1 Dry Quenched
Sample-2

(%) (%) (%)
Si02 15.1 24.47 24.85
A1203 3.5 5.12 5.15
Fe203 0.1 0.212 0.21
CaO 42.4 66.57 66.41
MgO 1.1 1.72 1.69
K20 0.6 0.08 0.08
CI 0 0.008 0.008
F 0.2 0.323 0.33
Lime Stone Factor 91 88.93 88.89
Silica Modulus 4.1 4.59 4.S9
Alunima Modulus 26.5 24.16 24.2
Whiteness
(On Hunter
whiteness scale) Not Applicable 90.02 90.1

Claims:
We claim:
1. A process for the production of white cement clinker; said process comprises the following steps:
a. crushing lime stone and clay through a crusher stacker reclaimer
and grinder to obtain fine particulate matter;
b. blending the particulate matter to obtain blended particulate mass;
c. heating the particulate mass in a kiln at a temperature between
1450 °C to 1500 °C to obtain hot cement clinker;
d. quenching the hot cement clinker in a closed chamber with a inert
gas stream to obtain decolorized cement clinker and hot inert gas
stream;
e. extracting sensible heat from the hot inert gas stream for energy
utilization; and
f. grinding the decolorized cement clinker to obtain white cement.
2. The process as claimed in claim 1, wherein the inert gas comprises a single element or a mixture of inert gases.
3. The process as claimed in claim 2, wherein the inert gas is at least one gas selected from the group consisting of nitrogen, argon, neon, helium, krypton, xenon and radon.
4. The process as claimed in claim 2, wherein the preferred inert gas is nitrogen.
5. The process as claimed in claim 1, wherein the hot cement clinker entering the closed chamber at a temperature of about 1200 °C.
6. The process as claimed in claim 1, wherein the temperature of the hot cement clinker in the closed chamber lowers to the range of 160 °C to 220 °C.

7. The process as claimed in claim 6, wherein the quenching step lowers the temperature of hot cement clinker below 200 °C.
8. The process as claimed in claim 1, wherein the temperature of the hot inert gas stream emanating from the closed chamber is about 500 °C -800 °C.
9. The process as claimed in claim 1, wherein the sensible heat from the hot inert gas stream is extracted by passing said hot inert gas stream through a waste heat recovery system.
10. The process as claimed in claim 1, wherein the quenching process conserves about 15 % to 30 % of the energy.
11. The process as claimed in claim 1, wherein the quenching process saves about 400 to 450 liters of water per ton of clinker.
12. The process as claimed in claim 1, wherein the quenching process provides the white cement comprising whiteness of about 90-95 on a hunter whiteness scale.
13. The process as claimed in claim 1, wherein the heat liberated per ton of cement clinker produced is in the range of 1,00,000 Kcal to 2,75,000 Kcal.

Documents:

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Patent Number

277129

Indian Patent Application Number

2695/MUM/2009

PG Journal Number

47/2016

Publication Date

11-Nov-2016

Grant Date

11-Nov-2016

Date of Filing

23-Nov-2009

Name of Patentee

GRASIM INDUSTRIES LIMITED

Applicant Address

BIRLAGRAM ,NAGDA-456331, MADHYA PRADESH,INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	CHHAPERWAL SUNIL	D3/1, VIKRAM NAGAR COLONY, POST. KHOR, NEEMUCH, MADHYA PRADESH, INDIA.
2	KAPOOR ,H. R.	RAJSHREE NAGAR, VIL.KHARIA KHANGAR, TEH. BHOPALGARH, DIST. JODHPUR-342606, RAJASTAN, INDIA
3	JAIN, R.C.	BIRLA WHITE, BUNGALOW NO. B-08, P.O. RAJSHREE NAGAR, VIL. KHARIA KHANGAR, TEH. BHOPALGARH, DIST. JODHPUR-342606, RAJASTHAN, INDIA
4	VYAS, INDER RAJ	PINJARA STREET, KHANDA FALSA, JODHPUR-342001, RAJASTHAN, INDIA

PCT International Classification Number

C04B7/47

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA