Title of Invention	AN IMPROVED PROCESS FOR MANUFACTURING PORTLAND CEMENT USING BAMBOO DUST FROM PAPER MILLS
Abstract	An improved process for manufacturing Portland cement using bamboo dust, which comprises pulverizing separately limestone, clay, coke or coal to a fineness of 90 micron or below and the bamboo dust to a fineness of 150 micron or below, mixing and homogenizing thoroughly, 65 - 75 wt % of the ground limestone, 10-16 wt% of ground clay, 4 - 10.5% by wt. of ground coke or coal and 1.5 - 8 wt % of the finely ground bamboo dust, mixing with 10 -15% by weight of water pelletizing the said mixture in the form of pellet by known procedures, firing the said pellets in the range of 1200 - 1450°C under air blast followed by cooling the resultant clinker to ambient temperature by blowing ambient air, grinding the clinker with 4 - 5% of gypsum to obtain the desired portland cement.

Title of Invention

AN IMPROVED PROCESS FOR MANUFACTURING PORTLAND CEMENT USING BAMBOO DUST FROM PAPER MILLS

Abstract

An improved process for manufacturing Portland cement using bamboo dust, which comprises pulverizing separately limestone, clay, coke or coal to a fineness of 90 micron or below and the bamboo dust to a fineness of 150 micron or below, mixing and homogenizing thoroughly, 65 - 75 wt % of the ground limestone, 10-16 wt% of ground clay, 4 - 10.5% by wt. of ground coke or coal and 1.5 - 8 wt % of the finely ground bamboo dust, mixing with 10 -15% by weight of water pelletizing the said mixture in the form of pellet by known procedures, firing the said pellets in the range of 1200 - 1450°C under air blast followed by cooling the resultant clinker to ambient temperature by blowing ambient air, grinding the clinker with 4 - 5% of gypsum to obtain the desired portland cement.

Full Text	The present invention relates to an improved process for • manufacturing Portland cement using Gamheo TUST from paper mills. More precisely, this invention relates to a process for producing ordinary Portland cement (DPC) by the black meal process using bamboo dust obtained as waste in the paper mills as a fuel and a raw material. Portland cement, the most common construction material, is made by grinding Portland cement clinker with a small quantity of gypsum. The clinkers are produced by burning a well proportioned and homogenized mixture containing calcareous (lime containing like limestone) and argillaceous silica, materials (alumina containing like clay) at high temperature of around 1500 degree Celsius.During the course of heating, the materials undergo drying, dehydroxylation, decarbonation etc. reactions forming the acidic and basic oxides which subsequently react at high temperature to form the various clinker constituents (phases). The silicates are the major constituents of the clinker. The di and tricalcium silicates together account for about 70 7% of the clinker and these are responsible for the strength charactristics of the cement. The tricalcium silicate phase is responsible for the initial strength characteristics of the cement and its formation takes place at about 13OO degree Celsius temperature. Cement clinkerization is therefore highly energy intensive. Fuel accounts for a major cost of the cement. In general, the fuel requirement for manufacturing cement by the^i shaft kiln technology is around 1OOO k.cal/kg of clinker. Cement clinkerization is done either in rotary or in shaft kiln. Large scale cement manufacturing is usually done by the rotary kiln technology. Such technology require large limestone deposits and assured markets. Coal, oil, gas etc. are the common fuels for the rotary kiln. The rotary kiln however is considered to be a versatile incinerator and any type of low grade fuel or combustible waste may be used as fuel as reported by S C Ahluwalia and C H Page, in the article 'Effect of low grade fuels, combustible wastes and non traditional raw materials, published in the Proceedings, 9th International Congress on the Chemistry of Cement, New Delhi, 1992, Vol.1, pages 83-124. The shaft kiln technology is ideally suited for manufacturing cement in small scale. The technology is based on the black meal process, wherein, the fuel is intermixed with the raw material and therefore the generated ash also takes part in the clinkerization process. The commonly used fuel for the shaft kiln technology is low volatile breese coke obtained as a bye product in the coke ovens of steel plants. Since coke ovens are localized, its availability and cost in some places are becoming scarce and high. Accordingly, there is a growing interest in developing processes for manufacturing cement by the black meal process by substituting a part or the entire amount of the conventional fuel coke breeze by alternative material. In countries like India, huge amounts of biomass are generated as waste in the fields and factories. These biomass contain various amount of carbonaceous materials like cellulose, hemicellulose, lignin, pentosan, resin, wax oil etc. The calorific values of the biomass rich in ash is low, whilst, those rich in oils, resins, waxes are high. Therefore, lignocellulosic materials may be thought of as fuel for producing cement clinker in the shaft kiln. In general, unlike the coke breeze, these materials are rich in volatile matter and their calorific values are less than the coke breeze. The ash content and physicochemical characteristics of the ash also varies from source to source. Rice husk obtained as waste material in the rice milling industries having calorific value of around 3OOO K.Cal/Kg, on combustion generate about 17-25 54 of its weight as ash and around 90'/, of the ash is silica, which is highly reactive. The husk have been described as a good source of fuel and a raw material for making Portland cement of various characteristics as described in Indian Patent No.172587 by K C Misra, D Bordoloi and P C Borthakur, Indian Patent Application Nos 993/Del/94 and 994/Del/92 by P Barkakati,D Bordoloi,A C Baruah,U C Borah and P C Borthakur. Literature reports on use of lignocellulosic materials other than that of the rice husk as source of fuel and raw material in black meal process of cement manufacturing is not available. Bamboo, soft wood etc. are used as the most common pulping material for manufacture of paper in India and many other countries. Processing of these materials for preparation of the pulp generate huge amount of wastes in the form of dust, chips etc. The quantity generated is enormous. On an average, a bamboo based paper mill producing around 30O tonnes of paper/day generates around 25-30 metric tonnes of bamboo dust. The common practice of disposal is to transport and dump the waste in open places nearer to the paper mill and burn the same. The calorific value of the waste over .£4000 K.cal/kg) are thus wasted. The ash content of bamboo dust is relatively small,(about 1OX by weight) and is comprised of silica, and small to traces of oxides of aluminium, iron, calcium, magnesium, sodium, potassium etc. The silica content is relatively small and alkli content is high. The cumulative deposits of the generated ash cause concern for disposal and associated pollution. The main object of the present invention is to provide a process for obtaining Portland cement by the black meal process utilising bamboo dust as a fuel and a raw material. Another object of the present invention is to develop a method of producing Portland cement at a relatively low temperature ideal for implementation at a small scale, using bamboo waste as a fuel and a raw material. Still another object of the present invention is to conserve nonrenewable fossil fuels like coal, petroleum etc. usually used as the source of fuel in cement manufacturing. Yet another object of the present invention is to utilize bamboo dust, a waste from the paper mills, for useful purposes and eliminate the problems associated with it's disposal. Accordingly, the present invention provides an improved •process for manufacturing Portland cement using Gamheo tust which comprises of pulverising separately limestone, clay, coke or coal to a fineness of 90 micron or below and bamboo dust to a fineness of 150 micron or below, mixing and homogenizing throughly, 65 - 75 wt % of the ground limestone, 10 - 16 wt % of ground clay 4 - 10.5 % by wt. of ground coke or coal and 1.5 - 8 wt % of the finely ground bamboo dust, mixing with 10 - 15 % by weight of water pelletizing the said mixture in the form of pellet by known procedures, firing the said pellets in the range of 1200 - 1450 °C under air blast followed by cooling the resultant clinker to ambient temperature by blowing ambient air, grinding the clinker with 4 - 5 % of gypsum to obtain the desired portland cement. The essential steps of the process of the present invention consist in separately grinding or Pulverising limestone, clay and coke or coal to a fineness in the range of 80-100 micron size and bamboo waste to a fineness of 150 micron size or below, mixing and homogenizing 50 -70 wt.% of ground limestone, 4 to 10 wt.% of ground clay and 4 to 12 wt.% of pulverized coal or coke and 2 to 10% by weight of ground bamboo and then agglomerating the mixture in the form of nodules of 8-12 mm diameter by known methods in a disc type nodulizer using water in the range of 10 - 15 % by wt. of the mixture and then igniting the agglomerates in a vertical shaft kiln at temperatures in the range of 1200-1450 deg. Celsius by known methods , cooling the resultant clinkers to ambient temperature by blowing air, discharging the clinkers from the kiln followed by grinding the same with 4-5 % by weight of gypsum to a Blaine's surface area of 3000-350O sq.cm/gm to obtain the Portland cement. The invention is illustrated with the following examples which should not be construed to limit the scope of the invention : Chemical analysis of the raw materials viz. limestone, clay, are presented in Table i. The proximate analysis of the fuels viz. coke breeze and bamboo dust and their ash analysis are presented in Table 2. Table 1 : Analysis of Raw materials (Table Removed) Table 2 : Proximate analysis of the fueis and their ash analyses (Dry basis) (Table Removed) Example 1 Limestone, clay and coke are separately ground to a fineness of below 90 micron size and bamboo dust was ground to less than 150 micron size. These materials are mixed in the proportions of 71.91, 15.17, 1O.32 and 2.58 % by weight of limestone, clay, coke and bamboo dust respectively and blended thoroughly in the dry state and then agglomerated in a disc type nodulizer in the form of spherical "nodules of 8-12 mm diameter by using a spray of water comprising of 1O % by wt. of the mix. The resultant agglomerates are then placed in a vertical sintering furnace similar to the vertical shaft kiln having provision for air entry at the bottom and lined inside with refractory material. The nodules are then fired under conditions simulating to the operation of the vertical shaft kiln for manufacture of cement. The clinkers obtained by firing at a maximum temperature of 1300 degree Celsius are then cooled by blowing air and then ground with 4 % gypsum in a mill to get the cement with Elaine's surface area of 3080 sq.cm./gm. The free lime content of the clinkers is 4.8 % by weight and its lime saturation factor is 0.89. The calculated alite (tricalcium silicate) and belite (dicalcium silicate) content of the cement are 20.OO and 45.1O % respectively. The initial and final seting time of the cement are respectively 113 and 140 minutes. The Le-Chatelier expansion is 35 mm. The 3,7 and 28 days compressive strength of the cement are respectively 251, 269,352 kg/cma and meet Indian Specification of ordinary Portland cement. Example 2 Limestone, clay and coke are separately ground to a fineness of below 90 micron size and bamboo dust was ground to less than 150 micron size. The materials are than mixed in the proportions of 71.91, 15.17,7.75 and 5.16 '/* by weight of limestone, clay, coke and bamboo dust respectively, blended thoroughly in the dry state and then agglomerated in a disc type nodulizer in the form of spherical nodules of 8-12 mm diameter by using a spray of water. The resultant agglomerates are then placed in a vertical sintering furnace similar to the vertical shaft kiln, having provision for air entry at the bottom and lined inside with refractory material. The nodules are then fired under conditions simulating to operation of the shaft kiln for manufacture of cement. The clinkers so produced by firing at a maximum temperature of 1300 degree Celsius are then cooled by blowing ambient air and then ground with 4 J4 gypsum in a mill to get the cement of Elaine's surface area of 308O sq.cm./gm. The free lime content of the clinkers is 5.5 % and its lime saturation factor is 0.92 % . The calculated alite (tricalcium silicate) and belite (dicalcium silicate) content of the cement are 23.53 and 41.79 % respectively. The initial and final seting times of the cement are respectively 88 and 108 mins. The 3, 7 and 28 days compressive strength of of the cement are respectively 222, 266 and 332 kg/cmz. The setting time and compressive strengths meet Indian Specification of ordinary Portland Cement. Example 3 Limestone, clay and coke are separately ground to a fineness of below 90 micron size and bamboo dust was ground to less than 150 micron size. These materials are than mixed in the proportion of 71.91, 15.17, 5.16 and 7.74 % by weight respectively, blended thoroughly in the dry state and than agglomerated in a disc type nodulizer in the form of spherical nodules of 8-12 mm diameter by using a spray of water. The resultant agglomerates are then placed in a vertical kiln having provision for air entry at the bottom, lined inside with refractory material. The nodules are then fired under condition simulating to operation of the vertical shaft kiln for manufacture of cement at a maximum temperature of 1280 degree Celsius, cooled to ambient temperature by blowing ambient air. The clinkers formed are then ground with 4% gypsum in a pot mill to get the cement of Elaine's surface area of 3264 sq.cm./gm The free lime content of the clinkers is 8.37 V> and its lime saturation factor is 0.94. The calculated alite and belite content of the cement are 18.56 and 44.71% respectively. The initial and final seting times of the cement are respectively 55 and 80 minutes. The 3,7 and 28 days compre-ssive strength of the cement are respectively 204,246 and 316 kg./cm.sq. The setting times and 3 and 7 days compressive strength of the cement meet Indian Specification of ordinary Portland Cement. The main advantages of the present invention are : 1. Utilization of bamboo dust, a waste material of paper mill as a source of fuel and raw material. 2. Manufacture of cement at a relatively low temperature. We Claim: 1. An improved process for manufacturing Portland cement using bamboo dust, which comprises pulverizing separately limestone, clay, coke or coal to a fineness of 90 micron or below and the bamboo dust to a fineness of 150 micron or below, mixing and homogenizing thoroughly, 65 - 75 wt % of the ground limestone, 10-16 wt% of ground clay, 4 - 10.5% by wt. of ground coke or coal and 1.5 - 8 wt % of the finely ground bamboo dust, mixing with 10 - 15% by weight of water pelletizing the said mixture in the form of pellet by known procedures, firing the said pellets in the range of 1200 - 1450°C under air blast followed by cooling the resultant clinker to ambient temperature by blowing ambient air, grinding the clinker with 4 - 5% of gypsum to obtain the desired portland cement. 2. A process, as claimed in claims 1 - 2, wherein, water is added in form of spray to agglomerate the raw materials. 3. A process, as claimed in claims 1 & 2, wherein, the pellets are preferably prepared in the size ranges of 8 - 12 mm. 4. A process, as claimed in claims 1-3, wherein the limestone is cement grade and contain around 44 - 52 % by weight of CaO and less than 3% MgO. 5. A process, as claimed in claims 1 - 4, wherein the clay used is a medium plastic one containing 45 - 70% SiO2, 16 - 40% A12O3, 4 - 10% Fe2O3 and the like. 6. An improved process for manufacturing Portland cement using bamboo dust substantially as herein described with reference to the examples.

Full Text

The present invention relates to an improved process for •

manufacturing Portland cement using Gamheo TUST from paper mills. More precisely, this invention relates to a process for producing ordinary Portland cement (DPC) by the black meal process using bamboo dust obtained as waste in the paper mills as a fuel and a raw material.
Portland cement, the most common construction material, is made by grinding Portland cement clinker with a small quantity of gypsum. The clinkers are produced by burning a well proportioned and homogenized mixture containing calcareous (lime containing like limestone) and argillaceous silica, materials (alumina containing like clay) at high temperature of around 1500 degree Celsius.During the course of heating, the materials undergo drying, dehydroxylation, decarbonation etc. reactions forming the acidic and basic oxides which subsequently react at high temperature to form the various clinker constituents (phases). The silicates are the major constituents of the clinker. The di and tricalcium silicates together account for about 70 7% of the clinker and these are responsible for the strength charactristics of the cement. The tricalcium silicate phase is responsible for the initial strength characteristics of the cement and its formation takes place at about 13OO degree Celsius temperature. Cement clinkerization is therefore highly energy intensive. Fuel accounts for a major cost of the cement. In general, the fuel requirement for manufacturing cement by the^i
shaft kiln technology is around 1OOO k.cal/kg of clinker. Cement clinkerization is done either in rotary or in shaft kiln. Large scale cement manufacturing is usually done by the rotary kiln technology. Such technology require large limestone deposits and assured markets. Coal, oil, gas etc. are the common fuels for the rotary kiln. The rotary kiln however is considered to be a versatile incinerator and any type of low grade fuel or combustible waste may be used as fuel as reported by S C Ahluwalia and C H Page, in the article 'Effect of low grade fuels, combustible wastes and non traditional raw materials, published in the Proceedings, 9th International Congress on the Chemistry of Cement, New Delhi, 1992, Vol.1, pages 83-124.
The shaft kiln technology is ideally suited for manufacturing cement in small scale. The technology is based on the black meal process, wherein, the fuel is intermixed with the raw material and therefore the generated ash also takes part in the clinkerization process. The commonly used fuel for the shaft kiln technology is low volatile breese coke obtained as a bye product in the coke ovens of steel plants. Since coke ovens are localized, its availability and cost in some places are becoming scarce and high.
Accordingly, there is a growing interest in developing processes for manufacturing cement by the black meal process by substituting a part or the entire amount of the conventional fuel coke breeze by alternative material.
In countries like India, huge amounts of biomass are generated as waste in the fields and factories. These biomass contain various amount of carbonaceous materials like cellulose, hemicellulose, lignin, pentosan, resin, wax oil etc. The calorific values of the biomass rich in ash is low, whilst, those rich in oils, resins, waxes are high. Therefore, lignocellulosic materials may be thought of as fuel for producing cement clinker in the shaft kiln. In general, unlike the coke breeze, these materials are rich in volatile matter and their calorific values are less than the coke breeze. The ash content and physicochemical characteristics of the ash also varies from source to source. Rice husk obtained as waste material in the rice milling industries having calorific value of around 3OOO K.Cal/Kg, on combustion generate about 17-25 54 of its weight as ash and around 90'/, of the ash is silica, which is highly reactive. The husk have been described as a good source of fuel and a raw material for making Portland cement of various characteristics as described in Indian Patent No.172587 by K C Misra, D Bordoloi and P C Borthakur, Indian Patent Application Nos 993/Del/94 and 994/Del/92 by P Barkakati,D Bordoloi,A C Baruah,U C Borah and P C Borthakur. Literature reports on use of lignocellulosic materials other than that of the rice husk as source of fuel and raw material in black meal process of cement manufacturing is not available.
Bamboo, soft wood etc. are used as the most common pulping material for manufacture of paper in India and many other countries. Processing of these materials for preparation of the pulp generate huge amount of wastes in the form of dust, chips etc. The quantity generated is enormous. On an average, a bamboo based paper mill producing around 30O tonnes of paper/day generates around 25-30 metric tonnes of bamboo dust. The common practice of disposal is to transport and dump the waste in open places nearer to the paper mill and burn the same. The calorific value of the waste over .£4000 K.cal/kg) are thus wasted. The ash content of bamboo dust is relatively small,(about 1OX by weight) and is comprised of silica, and small to traces of oxides of aluminium, iron, calcium, magnesium, sodium, potassium etc. The silica content is relatively small and alkli content is high. The cumulative deposits of the generated ash cause concern for disposal and associated pollution.
The main object of the present invention is to provide a process for obtaining Portland cement by the black meal process utilising bamboo dust as a fuel and a raw material. Another object of the present invention is to develop a method of producing Portland cement at a relatively low temperature ideal for implementation at a small scale, using bamboo waste as a fuel and a raw material. Still another object of the present invention is to conserve nonrenewable fossil fuels like coal, petroleum etc. usually used as the source of fuel in cement manufacturing. Yet another object of

the present invention is to utilize bamboo dust, a waste from the

paper mills, for useful purposes and eliminate the problems associated with it's disposal.
Accordingly, the present invention provides an improved

•process for manufacturing Portland cement using Gamheo tust which comprises of pulverising separately limestone, clay, coke or coal to a fineness of 90 micron or below and bamboo dust to a fineness of 150 micron or below, mixing and homogenizing throughly, 65 - 75 wt % of the ground limestone, 10
- 16 wt % of ground clay 4 - 10.5 % by wt. of ground coke or coal
and 1.5 - 8 wt % of the finely ground bamboo dust, mixing with 10
- 15 % by weight of water pelletizing the said mixture in the
form of pellet by known procedures, firing the said pellets in
the range of 1200 - 1450 °C under air blast followed by cooling
the resultant clinker to ambient temperature by blowing ambient
air, grinding the clinker with 4 - 5 % of gypsum to obtain the
desired portland cement.
The essential steps of the process of the present invention consist in separately grinding or Pulverising limestone, clay and coke or coal to a fineness in the range of 80-100 micron size and bamboo waste to a fineness of 150 micron size or below, mixing and homogenizing 50 -70 wt.% of ground limestone, 4 to 10 wt.% of ground clay and 4 to 12 wt.% of pulverized coal or coke and 2 to 10% by weight of ground bamboo and then agglomerating the mixture in the form of nodules of 8-12 mm diameter by known methods in a disc type nodulizer using water in the range of 10 - 15 % by wt. of the mixture and then igniting the agglomerates in a vertical shaft kiln at temperatures in the range of 1200-1450 deg. Celsius by known methods , cooling the resultant clinkers to ambient temperature by blowing air, discharging the clinkers

from the kiln followed by grinding the same with 4-5 % by weight of gypsum to a Blaine's surface area of 3000-350O sq.cm/gm to obtain the Portland cement.
The invention is illustrated with the following examples which should not be construed to limit the scope of the invention :
Chemical analysis of the raw materials viz. limestone, clay, are presented in Table i. The proximate analysis of the fuels viz. coke breeze and bamboo dust and their ash analysis are presented in Table 2.
Table 1 : Analysis of Raw materials
(Table Removed)

Table 2 : Proximate analysis of the fueis and their ash analyses (Dry basis)
(Table Removed)

Example 1
Limestone, clay and coke are separately ground to a fineness of below 90 micron size and bamboo dust was ground to less than 150 micron size. These materials are mixed in the proportions of 71.91, 15.17, 1O.32 and 2.58 % by weight of limestone, clay, coke and bamboo dust respectively and blended thoroughly in the dry state and then agglomerated in a disc type nodulizer in the form of spherical "nodules of 8-12 mm diameter by using a spray of water comprising of 1O % by wt. of the mix. The resultant agglomerates are then placed
in a vertical sintering furnace similar to the vertical shaft kiln having provision for air entry at the bottom and lined inside with refractory material. The nodules are then fired under conditions simulating to the operation of the vertical shaft kiln for manufacture of cement. The clinkers obtained by firing at a maximum temperature of 1300 degree Celsius are then cooled by blowing air and then ground with 4 % gypsum in a mill to get the cement with Elaine's surface area of 3080 sq.cm./gm.
The free lime content of the clinkers is 4.8 % by weight
and its lime saturation factor is 0.89. The calculated alite

(tricalcium silicate) and belite (dicalcium silicate) content of the cement are 20.OO and 45.1O % respectively. The initial and final seting time of the cement are respectively 113 and 140 minutes. The Le-Chatelier expansion is 35 mm. The 3,7 and 28 days compressive strength of the cement are respectively 251, 269,352 kg/cma and meet Indian Specification of ordinary Portland cement.
Example 2
Limestone, clay and coke are separately ground to a fineness of below 90 micron size and bamboo dust was ground to less than 150 micron size. The materials are than mixed in the proportions of 71.91, 15.17,7.75 and 5.16 '/* by weight of limestone, clay, coke and bamboo dust respectively, blended thoroughly in the dry state and then agglomerated in a disc type nodulizer in the form of spherical nodules of
8-12 mm diameter by using a spray of water. The resultant agglomerates are then placed in a vertical sintering furnace similar to the vertical shaft kiln, having provision for air entry at the bottom and lined inside with refractory material. The nodules are then fired under conditions simulating to operation of the shaft kiln for manufacture of cement. The clinkers so produced by firing at a maximum temperature of 1300 degree Celsius are then cooled by blowing ambient air and then ground with 4 J4 gypsum in a mill to get the cement of Elaine's surface area of 308O sq.cm./gm.
The free lime content of the clinkers is 5.5 % and its lime saturation factor is 0.92 % . The calculated alite (tricalcium silicate) and belite (dicalcium silicate) content of the cement are 23.53 and 41.79 % respectively. The initial and final seting times of the cement are respectively 88 and 108 mins. The 3, 7 and 28 days compressive strength of of the cement are respectively 222, 266 and 332 kg/cmz. The setting time and compressive strengths meet Indian Specification of ordinary Portland Cement.
Example 3
Limestone, clay and coke are separately ground to a fineness of below 90 micron size and bamboo dust was ground to less than 150 micron size. These materials are than mixed in the proportion of 71.91, 15.17, 5.16 and 7.74 % by weight respectively, blended thoroughly in the dry state and than agglomerated in a disc type nodulizer in the form of
spherical nodules of 8-12 mm diameter by using a spray of water. The resultant agglomerates are then placed in a vertical kiln having provision for air entry at the bottom, lined inside with refractory material. The nodules are then fired under condition simulating to operation of the vertical shaft kiln for manufacture of cement at a maximum temperature of 1280 degree Celsius, cooled to ambient temperature by blowing ambient air. The clinkers formed are then ground with 4% gypsum in a pot mill to get the cement of Elaine's surface area of 3264 sq.cm./gm
The free lime content of the clinkers is 8.37 V> and its lime saturation factor is 0.94. The calculated alite and belite content of the cement are 18.56 and 44.71% respectively. The initial and final seting times of the cement are respectively 55 and 80 minutes. The 3,7 and 28 days compre-ssive strength of the cement are respectively 204,246 and 316 kg./cm.sq. The setting times and 3 and 7 days compressive strength of the cement meet Indian Specification of ordinary Portland Cement.
The main advantages of the present invention are :
1. Utilization of bamboo dust, a waste material of paper
mill as a source of fuel and raw material.
2. Manufacture of cement at a relatively low temperature.

We Claim:
1. An improved process for manufacturing Portland cement using bamboo
dust, which comprises pulverizing separately limestone, clay, coke or coal
to a fineness of 90 micron or below and the bamboo dust to a fineness of
150 micron or below, mixing and homogenizing thoroughly, 65 - 75 wt %
of the ground limestone, 10-16 wt% of ground clay, 4 - 10.5% by wt. of
ground coke or coal and 1.5 - 8 wt % of the finely ground bamboo dust,
mixing with 10 - 15% by weight of water pelletizing the said mixture in the
form of pellet by known procedures, firing the said pellets in the range of
1200 - 1450°C under air blast followed by cooling the resultant clinker to
ambient temperature by blowing ambient air, grinding the clinker with 4 -
5% of gypsum to obtain the desired portland cement.
2. A process, as claimed in claims 1 - 2, wherein, water is added in form of
spray to agglomerate the raw materials.
3. A process, as claimed in claims 1 & 2, wherein, the pellets are preferably
prepared in the size ranges of 8 - 12 mm.
4. A process, as claimed in claims 1-3, wherein the limestone is cement
grade and contain around 44 - 52 % by weight of CaO and less than 3%
MgO.
5. A process, as claimed in claims 1 - 4, wherein the clay used is a medium
plastic one containing 45 - 70% SiO2, 16 - 40% A12O3, 4 - 10% Fe2O3 and
the like.
6. An improved process for manufacturing Portland cement using bamboo dust
substantially as herein described with reference to the examples.

Documents:

1122-del-1998-abstract.pdf

1122-del-1998-claims.pdf

1122-del-1998-correspondence-others.pdf

1122-del-1998-correspondence-po.pdf

1122-del-1998-description (complete).pdf

1122-del-1998-form-1.pdf

1122-del-1998-form-19.pdf

1122-del-1998-form-2.pdf

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Patent Number

215277

Indian Patent Application Number

1122/DEL/1998

PG Journal Number

10/2008

Publication Date

07-Mar-2008

Grant Date

22-Feb-2008

Date of Filing

27-Apr-1998

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001,INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DIPAK BORDOLOI	REGIONAL RESEARCH LABORATORY, JORHAT-785006 ASSAM,INDIA
2	AJIT CHANDRA BARUAH	REGIONAL RESEARCH LABORATORY, JORHAT-785006 ASSAM,INDIA
3	PRAKASH CHANDRA BORTHAKUR	REGIONAL RESEARCH LABORATORY, JORHAT-785006 ASSAM,INDIA

PCT International Classification Number

C04B 7/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA