Title of Invention	WHITE PORTLAND CEMENT CLINKER, HAVING CAPACITY TO FIX SULFUR, DERIVED FROM AN ORGANIC FUEL, METHOD FOR ITS PRODUCTION AND WHITE PORTLAND CEMENT COMPRISING IT .
Abstract	The invention discloses a White Portland cement clinker, with the capacity to fix sulfur derived from an organic fuel having a sulfur content greater than 5% S, used as a fuel in the calcination of said clinker, said clinker additionally exhibiting reduced fuel consumption during such calcination and useful for producing a fast setting cement, characterized in that said clinker comprises amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, 3CaO.AI2O3(C3A): 0 to 15, CaO.SO3(CS): 0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 2 to 15, 11CaO.7AI2O3.CaF2 (C11A7CaF2): 0 to 5, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: 0 to 0.5, and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal comprising CaO, SiO2, Al2O3 and CaF2, and using an organic fuel with a sulfur content higher than 5% as the main source of the clinker's SO3 content, at temperatures between 2192 °F and 2462 °F, without the addition of any SO3-containing additive to the raw meal as a main source of SO3 content in the clinker. The invention is also for a method of its production and white Portland cement comprising it.

Title of Invention

WHITE PORTLAND CEMENT CLINKER, HAVING CAPACITY TO FIX SULFUR, DERIVED FROM AN ORGANIC FUEL, METHOD FOR ITS PRODUCTION AND WHITE PORTLAND CEMENT COMPRISING IT .

Abstract

The invention discloses a White Portland cement clinker, with the capacity to fix sulfur derived from an organic fuel having a sulfur content greater than 5% S, used as a fuel in the calcination of said clinker, said clinker additionally exhibiting reduced fuel consumption during such calcination and useful for producing a fast setting cement, characterized in that said clinker comprises amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, 3CaO.AI2O3(C3A): 0 to 15, CaO.SO3(CS): 0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 2 to 15, 11CaO.7AI2O3.CaF2 (C11A7CaF2): 0 to 5, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: 0 to 0.5, and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal comprising CaO, SiO2, Al2O3 and CaF2, and using an organic fuel with a sulfur content higher than 5% as the main source of the clinker's SO3 content, at temperatures between 2192 °F and 2462 °F, without the addition of any SO3-containing additive to the raw meal as a main source of SO3 content in the clinker. The invention is also for a method of its production and white Portland cement comprising it.

Full Text	FIELD OF THE INVENTION The present invention is related to a new family of clinker and white portland cements compositions, and more particularly, to a family of white clinkers compositions with a high content of sulfur coming from, namely, sulfur in fuel fixing, and the properties of cements thus obtained. BACKGROUND OF THE INVENTION Portland cement clinker is basically composed of four crystalline stages: alite-. 3CaO.Si02 (C3S) , belite: 2CaO.Si02 (C2S) , tricalcic aluminate: 3CaO.Al2O3 (C3A) and tetracalcic aluminate: 4CaO.Al2o3. Fe2O3 (C4AF) , the latter, is the only one colored and therefore, the only one responsible for the characteristic color of the ordinary gray Portland cement. The ordinary Portland cement is the product from the Portland cement clinker grinding and a setting regulator, which traditionally has been gypsum (CaS04.2H20). Processes and plants used for clinker of white Portland Cement (P.C.) manufacturing are widely known in the art. Generally, manufacturing process White P.C. clinker differs from Gray P.C. in the following basic aspects: (1) Chemical: Since for obtaining a White P.C. clinker (the total Fe203 content from raw materials), in White P.C. clinker is controlled and most be less than 0.5%. This involves removing the main melting agent from the gray P.C. clinker and therefore, liquid stage will only be formed from calcium aluminates, that will crystallize after a cooling process as C3A, thus eliminating formation of the C4AF solid solution; responsible for the gray P.C. color. (2) Sintered: Removing main melting element from the gray Portland cement clinker, involves that the melting agent in the white P.C. clinker is in less amount and over all, that the temperature in the liquid stage increases, from 2440.4°F (in a gray P.C. clinker), to a temperature of 2642 - 2678°F (in a white P.C. clinker), thus demanding a higher fuel consumption during sintering, compared to the gray P.C. clinker sintering process. (3) Cooling: In the obtaining process of white P.C. clinker, typically clinker cooling process is tougher than in the gray P.C. clinker manufacturing process, trying to stabilize the most of Iron on a reduced state, (Fe2 + ) , that is less chromophore than (Fe3+). Despite the differences above mentioned between both Portland cement clinker manufacturing processes, basically the two Portland cement clinkers are generally constituted by the same main mineralogical stages: C3S, C2S, C3A and C4AF (exclusively for Portland cement gray clinker). Advantages of a white P.C. over a gray P.C., are basically their white color, for which it is widely used for exposed structures and texturized elements, which can be white or colored; it is also common that white Portland cement develops better strength to compression due to a high content on C3A, compared to a gray Portland cement. A disadvantage of a white Portland cement is its low resistance to sulfates attack, mainly due to the high content of C3A, that reacts to the environment sulfates and ettringite is produced when mortar or concrete is hardened, causing fissures or cracking. On the other hand, in the state of the art, it is known that sulfur coming from traditionally used fuels for the cement industry, such as gas (non sulfur containing) carbon (1-2% S) , fuel oil (2-4% S) and low sulfur content pet-coque ( anhydrite, CaOS03, and in the presence of alkali leaching it forms alkaline sulfates: Na2O.S03 and K2O.SO3. Said anhydrite and alkaline sulfates fixing on the clinker is a desirable factor since up to date it has represented, the only way of extracting sulfur from the interior of the furnace, avoiding blockings and obstructions of the kiln itself, as well as the emission of S0x to the atmosphere. In this way, sulfur, since it is a semi-volatile element, it forms within the furnace, a cycle which re- concentrates sulfur and once it reaches a critical SO3 evaporating concentration, it is associated to the kiln clustering that makes kiln operation difficult and unstable reducing its production, and can even form serious blockings, that may involve a stoppage in the kiln itself. On the other hand, fuel-oil cost is inversely- proportional to its sulfur content. For this reason, the high sulfur content pet-coke (S > 5%), represents an opportunity for the cement industry due to its availability at the lower cost. Unfortunately, the use of said fuel shows the inconvenient that it requires special care for the operation; and new methods that could ease use without detriment to the furnace operation continuity. This is, the use of the pet-coke as fuel, in one hand, generates the necessary heat to keep the process temperature, and on the other, produces a higher amount of SO2 this means an important amount that can produce blockings on the pre- heater and form rings on the rotating kiln, which generates troubles on the operation, reducing its efficiency and in more serious cases, it does not allow to continue its operation. On one hand, and particularly in relation to the Portland cement clinker, in the state of the art there are numerous efforts aimed to facilities, equipment and/or processes design, for the use of solid fuels with a high sulfur content, in order to solve the problem associated to SO2 forming and accumulation. However, most of processes and/or plants that manufacture Portland cement clinker and use a solid fuel with a high sulfur content, present certain disadvantages such as complexity of processes and equipments, as well as high operational costs. Examples of said efforts are disclosed in, for example, the United States application No. 4,465,460 entitled "Cement clinker production" issued to Paul Cosar on August 14, 1984; United States applications No. 4,662,945 and 4,715,811 both entitled "Process and apparatus for manufacturing poor cement clinker in sulfur" issued to Thomas R. Lawall on May 5, 1987 and in December, 1987 respectively; the United States application No, 6,142,771 entitled "Cement clinker production control using high sulfur content fuel within a rotating kiln with a Lelep-Lepol displaceable grid through the sulfur final analysis in the final product", issued to Joseph Doumet on November 7, 2000; the Chinese Application No. 1,180,674 issued to Wang Xinchang et al on May 6, 1998 entitled "Method for producing high quality cement using pet-coke with a high sulfur content". A recent effort to solve problems associated to the use of high sulfur content coke, is disclosed by Mexican Application No. PA/a/2001/007228 entitled "Method of producing cement clinker using high sulfur content pet- coke" filed on July 13, 2 0 01 by Trademarks Europa, S.A. de C.V., which is a subsidiary of CEMEX group. On this application, a method to produce cement clinker that allows a more economic and efficient use of fuels with a high sulfur content such as pet-coke and that minimizes problems associated to blocking and incrustations due to the high concentration of SO2 and/or SO3 on the system. It is described in this document, the relationship to a high quality cement clinker that does not require additives to improve its final physical properties. On the other hand, there is a current of scientists and technologists who have focused their efforts on the reduction of the Portland cement clinker sintering, through row mix or raw meal chemical modifications, and have frequently used non-traditional mineralizers and melting agents. Examples of this current are generally described in the United States application No. 5,698,027 entitled "Method and Plant for manufacturing mineralized Portland cement clinker" granted to F.L. Smidth & Co., which is related to a mineralizer such as gypsum, fluorite, etc., as a control parameter for preventing or reducing problems associated to the rotating kiln operation; the Spain application No. 542,6 91 "Process for obtaining white clinker with a low fuel consumption using fluorite and sulphates as raw meal components", describes a process for producing a clinker composition which is formed under lower temperatures compared to traditional temperatures for the Portland clinker manufacturing", forming a new liquid phase called f luorelestadite: 3C2S. 3CaO4.CaF2. Besides, said cements, exhibit/show some problems with strength development, over all, at early ages (1 and 3 days) , even when strength increases at long ages (2 8 days and more) , compared to strength developed by common Portland cement. There is a third group of researchers who have found non-Portland clinkers cementing compositions, based on the formation of a phase rich in sulfur, calcium sulphoaluminate: 4CaO.3Al2O3. SO3 (C4A3S) ; said calcium sulphoaluminate based cements, exhibit an accelerated development of initial strengths compared to Portland cement, due to C4A3S hydration to form ettingite. Examples of this current are United States application No. 6,149,724 to Poo Ulibarri et al, granted to CEMEX in 2000, or the Canadian application No. 21933 9 and European application No. 0 812 811. In 1994, United States of America application No. 5,356,472 "Portland cement clinker and Portland cement", to Ivan Odler, discloses a method for manufacturing gray- clinkers under low forming temperatures, for example between 2102°F- 2462°F, clinker was formed by C3S, C4A3S and C4AF phases and practically without C2S and C3A, if to the raw mix containing CaO, SiO2, A12O3, and Fe2O3 was added an inorganic additive containing SO3 and other inorganic additive containing fluorine and strengths of cement obtained were comparable to the conventional gray Portland cement, when cement was prepared with a clinker of a 8 0% C3S, 10% C4A3S and 10% C4AF composition. However, any document of the prior art is related to the main object of the present invention, which is to produce a family of mineralogical compositions of white clinkers, formed by C3S, C2S, C4A3S, C3A, C11A7.CaF2, CS phases, without the presence of C4AF, with a high capacity of fixing sulfur coming from pet-coke as a sulfur source and which enables the use of a high sulfur content fuels (> 5% S) , using the conventional infrastructure of cement plants, for the production of white portland cements with compression strength similar or even greater to the conventional white Portland cement strength. Therefore, it is an objective of the present invention to provide new clinker and white portland cement compositions with high capacity of fixing sulfur coming from pet-coke with a high sulfur content, used as fuel. Another objective of the present invention is to provide new clinker and white Portland cement compositions exhibiting low fuel consumption on its manufacturing process and having fast setting developing increased compression initial strengths. It is further another object of the present invention to provide new clinker and white portland cement compositions using the conventional cement Plants infrastructure. BRIEF DESCRIPTION OF THE INVENTION The present invention is related to a new family of white portland cement clinker compositions, with a high capacity of fixing sulfur coming from pet-coke with a high sulfur content, used as a fuel, and with white portland cement properties thus obtained. White portland cement clinker of the present invention comprises the amounts of clinker phases in percentage by weight, as follows: from 40 to 75% of C3S, from 10 to 35% of C2S, from 0 to 15% of C3A, without C4AF, from 0 to 10% of Cs, from 2 to 15% of C4A3S, from 0 to 5 of C11A7.CaF2, %CaF2 total from 0.3 to 1.5 measured as CaF2, %Fe2O3 from 0 to 0.5%; and a content of SO3 between 1.5 and 5% by weight obtained through a raw meal calcination mainly containing CaO, SiO2, Al2O3, y CaF2, using pet-coke as fuel with a sulfur content higher than 5%, at temperatures ranging between 2192 and 2462°F, without the addition of any additive containing SO3 to the raw meal. DETAILED DESCRIPTION OF THE INVENTION The present invention is related to a new family of white portland cement clinker compositions based on factors such as, alite (C3S) formation temperatures and calcium sulphoaluminate (C4A3s) decomposition; the use of high sulfur content organic fuels that provide cement clinker a SO3 content of 1.5 to 5% by weight; and sintering temperature reduction. It is widely known that alite formation temperature for a Portland cement clinker is approximately of 2516°F, while calcium sulphoaluminate decomposition temperature for a white portland cement clinker is approximately 2462°F. Taking into account these criteria among others, inventors have discovered that a new family of white portland cement clinker compositions can be obtained through the use of adequate mineralogical phases (C3S, C2S, C3A, CS , C4A3S and C11A7.CaF2) of cement clinker and through the reduction of sintering temperature, using a high sulfur content organic source, without having problems associated to the use of said organic source as fuel (for example, high sulfur content pet-coke) which has a sulfur content higher than 5% . White portland cement, prepared from the above described clinker by fixing sulfur supplied mainly by high sulfur content pet-coke (>5% S) , in the form of calcium sulphoaluminate, C4A3s, exhibits an excellent increase in the compression strength, particularly it exhibits an accelerated development of initial strengths, specially curing the interval from 1 to 3 days. It is specifically referred to the illustrative embodiments as follows: Total content of SO3 in cement shall be between 3 an 10% by weight obtained through the raw meal calcination containing CaO, SiO2, Al2O3 and CaF2, using pet-coke as fuel, with a sulfur content higher than 5%, without the addition of any additive containing SO3 in the raw meal. A white Portland cement clinker can include the following amounts from the clinker phases in % by weight: 3CaO.SiO2 (C3S): 4O to 75, 2CaO.SiO2 (C3S): 10 to 35, 3CaO.Al2O3 (C3A): 0 to 15, CaO.SO2 (Cs): 0 to 10, 4CaO.3Al2O3 . SO3 (C4A3s): 2 to 15, HCaO. 7A12O3 . CaF2 (C11A7.CaF2) : 0 to 5, Total %CaF2: 0.3 to 1.5 measured as CaF2, %Fe2O3: 0 to 0.5, And a SO3 content between 1.5 and 5% by weight. Clinker is obtained through a raw meal calcination containing CaO, SiO2, A12O3 and CaF2, using pet-coke as fuel with a sulfur content higher than 5% at temperatures between 2192°F to 2462°F without the addition of any additive containing SO3 to the raw meal. A cement clinker with percentages by weight of the following clinker phases is preferred. C3S: 40 to 75, C2S: 10 to 35, Cs: 0 to 10, C4A3S: 5 to 15, CnA7.CaF2: 2 to 5, Total %CaF2: 0.3 to 1.5 measured as CaF2, %Fe2O3: In another embodiment of the present invention, a cement clinker with percentages by- weight of the following clinker phases is more preferred: C3S: 40 to 75, C2S: 10 to 35, CS: 0 to 10, C4A3S: 5 to 15, Total %CaF2: 0.3 to 1.5 measured as CaF2, %Fe2O3: Yet in another embodiment of the present invention, a cement clinker with percentages by- weight of the following clinker phases is more preferred: C3S: 40 to 75, C2S: 10 to 35, C3A: 5 to 15, CS: 0 to 10, C4A3S: 2 to 10, Total %CaF2: 0.3 to 1.5 measured as CaF2, %Fe2O3: Clinker calcination can be controlled to produce specific amounts of C2S and C3A phases, such as the addition of C2S and C3A clinker phases, and must be higher or equal to 10% by weight. Preferably C3A clinker phase is absent. Clinker phase forming is eased through CaF2 percentage which is about 0.3 to 1.5 measured as CaF2 in the raw meal. The preferred range is between 0.2 and 1.0% measured as CaF2 in the raw meal. A preferred SO3 content in the clinker can be indicated as 1.5 to 5% by weight, mainly supplied through the organic fuel such as pet-coke with a sulfur % higher than 5%. However, it is also possible to optionally complement the S03 content in the clinker with another inorganic sources selected from the group consisting of plaster, anhydrite or industrial debris containing sulfur. Corresponding calcium sulphate can be used to prepare finished white Portland cement. To optimize setting reaction, according to an embodiment, it is suggested that the clinker be grinded in a specific area of 465 to 775 in2/g measured according to the ASTM C-204 standard through Blaine. Forming a sulfur-rich phase, calcium sulphoaluminate: 4CaO. 3A12O3. SO3 (C4A3S), shows an accelerated development of initial strength compared to those of Portland cement, due to C4A3S hydration to form ettingite. Therefore, cements according to the present invention with C4A3s contents under 15% by weight, do not practically exhibit any expansion, for which, said cement has an initial strength exceeding that of a common Portland cement. On the other hand, during the clinker calcination of the present invention, less melted phase is formed (which is also due to the low temperature of calcination), which drives to a relatively porous clinker, in return, the clinker has a better grinding capacity, and grinding costs are reduced to the same specific area. Particularly, another relevant advantage of the clinker herein, is that alite and belite crystals sizes are less than 25 micrometers, which provides better grinding easiness than the conventional white Portland cement clinker. Clinker has a free lime percentage less than 1.5%, this is, it shows a free lime content similar to that of a white Portland cement clinker, but sintered at 392°F under the traditional white Portland clinker sintering temperature. The present invention will be better explained in detail based upon several examples. However, following examples are provided only for illustrative purposes, and it is not intended to limit the scope of the present invention. Sample 1 describes a cement free of C3A, but comprises a 9% by weight of C4A3s and 4% by weight of CuA7.CaF2. Sample 2 describes a cement free of C3A and C11A7.CaF2, but comprising a 12% by weight of C4A3s. Sample 3 describes a cement free of C11A7.CaF2, but comprising a 7% by weight of C3A and 3% by weight of C4A3S. Percentages from other clinker phases, SO3 content in clinker, selected calcination temperature, as well as the total of SO3 in cement are shown in the table below, including compression strength values measured after 1,3,7 and 28 days. To illustrate the advantages that can be obtained with cement of the present invention, a conventional Portland cement, calcined at 2642°F, is also shown as sample 4. Data show that sample 2, according to the present invention, exhibits a significant increase on compression strength at all ages and samples 1 and 3, show comparable strength to those developed by sample 4 which is the reference of white Portland cement and calcined at 2642°F. Besides, white portland cement of the present invention has initial setting time from 10 to 45 minutes, measured according to the ASTM C-191 standard through Vicat. In a particularly preferred embodiment of the present invention, white portland cement comprising clinker, which can be mixed with other materials such as limestone, slag, fly ash and/or puzolanic materials. Even when certain embodiment of the present invention has been illustrated and described, it should be noted that numerous possible modifications can be made. The present invention, therefore, shall not be considered as limited excepting for what the prior art demands and for the spirit of the claims attached hereto. We claim: 1. White Portland cement clinker, with the capacity to fix sulfur derived from an organic fuel having a sulfur content greater than 5% S, used as a fuel in the calcination of said clinker, said clinker additionally exhibiting reduced fuel consumption during such calcination and useful for producing a fast setting cement, characterized in that said clinker comprises amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, 3CaO.AI2O3(C3A):0 to 15, CaO.SO3 (CS): 0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 2 to 15, 11CaO.7AI2O3.CaF2 (C11A7CaF2): 0 to 5, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: 0 to 0.5, and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal comprising CaO, SiO2, Al2O3 and CaF2, and using an organic fuel with a sulfur content higher than 5% as the main source of the clinker's SO3 content, at temperatures between 2192 °F and 2462 °F, without the addition of any SO3-containing additive to the raw meal as a main source of SO3 content in the clinker. 2. The white Portland cement clinker as claimed in claim 1, wherein said clinker comprises the amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, CaO.SO3(Cs):0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 5 to 15, 11CaO.7AI2O3.CaF2 (C11A7CaF2,): 2 to 5, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal mainly containing CaO, SiO2, Al2O3 and CaF2, using as fuel pet-coke with a sulfur content higher than 5%, at a temperature of 2282 °F, without any SO3-containing additive to the raw meal as a main source of SO3 content in the clinker, wherein the absence of C3A results in a clinker useful in the manufacture of cements resistant to sulfates. 3. The white Portland cement clinker as claimed in claim 1, wherein said clinker comprises the amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2(C2S):10 to 35, CaO.SO3(Cs): 0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 5 to 15, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal mainly containing CaO, SiO2, Al2O3 and CaF2, using as fuel pet-coke with a sulfur content higher than 5%, at a temperature of 2282 °F, without any SO3-containing additive to the raw meal as a main source of SO3 content in the clinker, wherein the absence of C3A results in a clinker useful in the manufacture of cements resistant to sulfates. 4. The white Portland cement clinker as claimed in claim 1, wherein said clinker comprises the amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, 3CaO.AI2o3(C3A): 5 to 15, CaO.SO3(CS): 0 to10, 4CaO.3AI2O3.SO3 (C4A3S): 2 to 10, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal mainly containing CaO, SiO2, Al2O3 and CaF2, using as fuel pet-coke with a sulfur content higher than 5% as the main source of the clinker's S03 content, at a temperature of 2462 °F, without any SO3-containing additive to the raw meal. 5. The white Portland cement clinker as claimed in claim 1, wherein the SO3 content of the cement clinker is derived from pet-coke with a sulfur percentage higher than 5%. 6. A white Portland cement comprising the cement clinker as claimed in claim 1, mixed with at least one of other materials selected from the group consisting of lime, slag, fly ash and other pozzolanic materials. 7. The white Portland cement clinker as claimed in claim 1, wherein the organic fuel is pet-coke. 8. A method of producing a white Portland cement clinker as claimed in claim 7, comprising the steps of: subjecting a raw meal comprising CaO, SiO2, Al2O3 and CaF2, to a calcination at temperatures between 2192 °F, and 2462 °F; using pet-coke having a high sulfur content greater than 5% S as the calcination fuel and as the main source of the clinker's SO3 content; said raw meal having been mixed so as to form upon calcination a white Portland cement clinker having phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, 3CaO.AI2O3 (C3A): 0 to 15, CaO.SO3(Cs): 0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 2 to 15, 11Ca0.7AI2O3.CaF2 (C11A7CaF2): 0 to 5, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: 0 to 0.5, and a SO3 content between 1.5 and 5% by weight, without the addition of any SO3- containing additive to the raw meal as a main source of SO3 content in the clinker. 9. The white Portland cement clinker as claimed in claim 7, wherein the addition of the amounts of C2S and C3A clinker phases is higher than or equal to 10% by weight. 10. The white Portland cement clinker as claimed in claim 7, wherein the total CAF2 percentage amount in the raw meal is from 0.2 to 1.0% by weight measured as CaF2. 11. The white Portland cement clinker as claimed in claim 7, wherein the clinker SO3 content is supplemented with other inorganic sources selected from the group consisting of plaster, anhydrite, and the industrial debris containing sulfur. 12. The white Portland cement clinker as claimed in claim 7, wherein the alite, C3S, and belite, C2S, are crystals with sizes smaller than 25 micrometers, which provides a better ease of grinding than the conventional white Portland cement clinker. 13. The white Portland cement clinker as claimed in any of claims 2 to 4 and 7, wherein said clinker has a free lime percentage less than 1.5%. 14. A white Portland cement comprising the cement clinker as claimed in claim 7, and wherein the SO3 content of said cement is between 3.0 and 10%. 15. The white Portland cement as claimed in claim 14, wherein the specific area is 465 to 775 in2/g measured according to the ASTM C-204 standard through Blaine. 16. The white Portland cement as claimed in claim 14, wherein the initial setting time is between 10 and 45 minutes measured according to the ASTM C-191 standard through Vicat. 17. The white Portland cement as claimed in claim 14, wherein the resistance to compression measured according to ASTM C-109 is 15 to 25 N/mm2 at 1 day, 25 to 35 N/mm2 at 3 days, 40 to 44 N/mm2 at 7 days, and 50 to 70 N/mm2 at 28 days. 18. The white Portland cement as claimed in claim 14, wherein the SO3 content of the cement is 3.5 to 10 wt. %. The invention discloses a White Portland cement clinker, with the capacity to fix sulfur derived from an organic fuel having a sulfur content greater than 5% S, used as a fuel in the calcination of said clinker, said clinker additionally exhibiting reduced fuel consumption during such calcination and useful for producing a fast setting cement, characterized in that said clinker comprises amounts of clinker phases in percentage by weight, as follows: 3CaO.SiO2 (C3S): 40 to 75, 2CaO.SiO2 (C2S): 10 to 35, 3CaO.AI2O3(C3A): 0 to 15, CaO.SO3(CS): 0 to 10, 4CaO.3AI2O3.SO3 (C4A3S): 2 to 15, 11CaO.7AI2O3.CaF2 (C11A7CaF2): 0 to 5, %CaF2Total: 0.3 to 1.5 measured as CaF2, %Fe2O3: 0 to 0.5, and a SO3 content between 1.5 and 5% by weight obtained through the calcination of a raw meal comprising CaO, SiO2, Al2O3 and CaF2, and using an organic fuel with a sulfur content higher than 5% as the main source of the clinker's SO3 content, at temperatures between 2192 °F and 2462 °F, without the addition of any SO3-containing additive to the raw meal as a main source of SO3 content in the clinker. The invention is also for a method of its production and white Portland cement comprising it.

Full Text

FIELD OF THE INVENTION
The present invention is related to a new
family of clinker and white portland cements compositions,
and more particularly, to a family of white clinkers
compositions with a high content of sulfur coming from,
namely, sulfur in fuel fixing, and the properties of
cements thus obtained.
BACKGROUND OF THE INVENTION
Portland cement clinker is basically composed of
four crystalline stages: alite-. 3CaO.Si02 (C3S) , belite:
2CaO.Si02 (C2S) , tricalcic aluminate: 3CaO.Al2O3 (C3A) and
tetracalcic aluminate: 4CaO.Al2o3. Fe2O3 (C4AF) , the latter,
is the only one colored and therefore, the only one
responsible for the characteristic color of the ordinary
gray Portland cement.
The ordinary Portland cement is the product from
the Portland cement clinker grinding and a setting
regulator, which traditionally has been gypsum (CaS04.2H20).
Processes and plants used for clinker of white
Portland Cement (P.C.) manufacturing are widely known in
the art. Generally, manufacturing process White P.C.
clinker differs from Gray P.C. in the following basic
aspects:
(1) Chemical: Since for obtaining a White P.C.
clinker (the total Fe203 content from raw materials), in
White P.C. clinker is controlled and most be less than
0.5%. This involves removing the main melting agent from
the gray P.C. clinker and therefore, liquid stage will only
be formed from calcium aluminates, that will crystallize
after a cooling process as C3A, thus eliminating formation
of the C4AF solid solution; responsible for the gray P.C.
color.
(2) Sintered: Removing main melting element from
the gray Portland cement clinker, involves that the melting
agent in the white P.C. clinker is in less amount and over
all, that the temperature in the liquid stage increases,
from 2440.4°F (in a gray P.C. clinker), to a temperature of
2642 - 2678°F (in a white P.C. clinker), thus demanding a
higher fuel consumption during sintering, compared to the
gray P.C. clinker sintering process.
(3) Cooling: In the obtaining process of white
P.C. clinker, typically clinker cooling process is tougher
than in the gray P.C. clinker manufacturing process, trying
to stabilize the most of Iron on a reduced state, (Fe2 + ) ,
that is less chromophore than (Fe3+).
Despite the differences above mentioned between
both Portland cement clinker manufacturing processes,
basically the two Portland cement clinkers are generally
constituted by the same main mineralogical stages: C3S, C2S,
C3A and C4AF (exclusively for Portland cement gray clinker).
Advantages of a white P.C. over a gray P.C., are
basically their white color, for which it is widely used
for exposed structures and texturized elements, which can
be white or colored; it is also common that white Portland
cement develops better strength to compression due to a
high content on C3A, compared to a gray Portland cement. A
disadvantage of a white Portland cement is its low
resistance to sulfates attack, mainly due to the high
content of C3A, that reacts to the environment sulfates and
ettringite is produced when mortar or concrete is hardened,
causing fissures or cracking.
On the other hand, in the state of the art, it is
known that sulfur coming from traditionally used fuels for
the cement industry, such as gas (non sulfur containing)
carbon (1-2% S) , fuel oil (2-4% S) and low sulfur content
pet-coque ( anhydrite, CaOS03, and in the presence of alkali leaching
it forms alkaline sulfates: Na2O.S03 and K2O.SO3. Said
anhydrite and alkaline sulfates fixing on the clinker is a
desirable factor since up to date it has represented, the
only way of extracting sulfur from the interior of the
furnace, avoiding blockings and obstructions of the kiln
itself, as well as the emission of S0x to the atmosphere.
In this way, sulfur, since it is a semi-volatile
element, it forms within the furnace, a cycle which re-
concentrates sulfur and once it reaches a critical SO3
evaporating concentration, it is associated to the kiln
clustering that makes kiln operation difficult and unstable
reducing its production, and can even form serious
blockings, that may involve a stoppage in the kiln itself.
On the other hand, fuel-oil cost is inversely-
proportional to its sulfur content. For this reason, the
high sulfur content pet-coke (S > 5%), represents an
opportunity for the cement industry due to its availability
at the lower cost.
Unfortunately, the use of said fuel shows the
inconvenient that it requires special care for the
operation; and new methods that could ease use without
detriment to the furnace operation continuity. This is, the
use of the pet-coke as fuel, in one hand, generates the
necessary heat to keep the process temperature, and on the
other, produces a higher amount of SO2 this means an
important amount that can produce blockings on the pre-
heater and form rings on the rotating kiln, which generates
troubles on the operation, reducing its efficiency and in
more serious cases, it does not allow to continue its
operation.
On one hand, and particularly in relation to the
Portland cement clinker, in the state of the art there are
numerous efforts aimed to facilities, equipment and/or
processes design, for the use of solid fuels with a high
sulfur content, in order to solve the problem associated to
SO2 forming and accumulation. However, most of processes
and/or plants that manufacture Portland cement clinker and
use a solid fuel with a high sulfur content, present
certain disadvantages such as complexity of processes and
equipments, as well as high operational costs. Examples of
said efforts are disclosed in, for example, the United
States application No. 4,465,460 entitled "Cement clinker
production" issued to Paul Cosar on August 14, 1984; United
States applications No. 4,662,945 and 4,715,811 both
entitled "Process and apparatus for manufacturing poor
cement clinker in sulfur" issued to Thomas R. Lawall on May
5, 1987 and in December, 1987 respectively; the United
States application No, 6,142,771 entitled "Cement clinker
production control using high sulfur content fuel within a
rotating kiln with a Lelep-Lepol displaceable grid through
the sulfur final analysis in the final product", issued to
Joseph Doumet on November 7, 2000; the Chinese Application
No. 1,180,674 issued to Wang Xinchang et al on May 6, 1998
entitled "Method for producing high quality cement using
pet-coke with a high sulfur content".
A recent effort to solve problems associated to
the use of high sulfur content coke, is disclosed by
Mexican Application No. PA/a/2001/007228 entitled "Method
of producing cement clinker using high sulfur content pet-
coke" filed on July 13, 2 0 01 by Trademarks Europa, S.A. de
C.V., which is a subsidiary of CEMEX group. On this
application, a method to produce cement clinker that allows
a more economic and efficient use of fuels with a high
sulfur content such as pet-coke and that minimizes problems
associated to blocking and incrustations due to the high
concentration of SO2 and/or SO3 on the system. It is
described in this document, the relationship to a high
quality cement clinker that does not require additives to
improve its final physical properties.
On the other hand, there is a current of
scientists and technologists who have focused their efforts
on the reduction of the Portland cement clinker sintering,
through row mix or raw meal chemical modifications, and
have frequently used non-traditional mineralizers and
melting agents. Examples of this current are generally
described in the United States application No. 5,698,027
entitled "Method and Plant for manufacturing mineralized
Portland cement clinker" granted to F.L. Smidth & Co.,
which is related to a mineralizer such as gypsum, fluorite,
etc., as a control parameter for preventing or reducing
problems associated to the rotating kiln operation; the
Spain application No. 542,6 91 "Process for obtaining white
clinker with a low fuel consumption using fluorite and
sulphates as raw meal components", describes a process for
producing a clinker composition which is formed under lower
temperatures compared to traditional temperatures for the
Portland clinker manufacturing", forming a new liquid phase
called f luorelestadite: 3C2S. 3CaO4.CaF2. Besides, said

cements, exhibit/show some problems with strength
development, over all, at early ages (1 and 3 days) , even
when strength increases at long ages (2 8 days and more) ,
compared to strength developed by common Portland cement.
There is a third group of researchers who have
found non-Portland clinkers cementing compositions, based
on the formation of a phase rich in sulfur, calcium
sulphoaluminate: 4CaO.3Al2O3. SO3 (C4A3S) ; said calcium
sulphoaluminate based cements, exhibit an accelerated
development of initial strengths compared to Portland
cement, due to C4A3S hydration to form ettingite. Examples
of this current are United States application No. 6,149,724
to Poo Ulibarri et al, granted to CEMEX in 2000, or the
Canadian application No. 21933 9 and European application
No. 0 812 811.
In 1994, United States of America application No.
5,356,472 "Portland cement clinker and Portland cement", to
Ivan Odler, discloses a method for manufacturing gray-
clinkers under low forming temperatures, for example
between 2102°F- 2462°F, clinker was formed by C3S, C4A3S and
C4AF phases and practically without C2S and C3A, if to the
raw mix containing CaO, SiO2, A12O3, and Fe2O3 was added an
inorganic additive containing SO3 and other inorganic
additive containing fluorine and strengths of cement
obtained were comparable to the conventional gray Portland
cement, when cement was prepared with a clinker of a 8 0%
C3S, 10% C4A3S and 10% C4AF composition.
However, any document of the prior art is related
to the main object of the present invention, which is to
produce a family of mineralogical compositions of white
clinkers, formed by C3S, C2S, C4A3S, C3A, C11A7.CaF2, CS
phases, without the presence of C4AF, with a high capacity
of fixing sulfur coming from pet-coke as a sulfur source
and which enables the use of a high sulfur content fuels (>
5% S) , using the conventional infrastructure of cement
plants, for the production of white portland cements with
compression strength similar or even greater to the
conventional white Portland cement strength.
Therefore, it is an objective of the present
invention to provide new clinker and white portland cement
compositions with high capacity of fixing sulfur coming
from pet-coke with a high sulfur content, used as fuel.
Another objective of the present invention is to
provide new clinker and white Portland cement compositions
exhibiting low fuel consumption on its manufacturing
process and having fast setting developing increased
compression initial strengths.
It is further another object of the present
invention to provide new clinker and white portland cement
compositions using the conventional cement Plants
infrastructure.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is related to a new
family of white portland cement clinker
compositions, with a high capacity of fixing sulfur
coming from pet-coke with a high sulfur content,
used as a fuel, and with white portland cement
properties thus obtained. White portland cement
clinker of the present invention comprises the
amounts of clinker phases in percentage by weight,
as follows: from 40 to 75% of C3S, from 10 to 35% of
C2S, from 0 to 15% of C3A, without C4AF, from 0 to
10% of Cs, from 2 to 15% of C4A3S, from 0 to 5 of
C11A7.CaF2, %CaF2 total from 0.3 to 1.5 measured as
CaF2, %Fe2O3 from 0 to 0.5%; and a content of SO3
between 1.5 and 5% by weight obtained through a raw
meal calcination mainly containing CaO, SiO2, Al2O3,
y CaF2, using pet-coke as fuel with a sulfur content
higher than 5%, at temperatures ranging between
2192 and 2462°F, without the addition of any
additive containing SO3 to the raw meal.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is related to a new
family of white portland cement clinker
compositions based on factors such as, alite (C3S)
formation temperatures and calcium sulphoaluminate
(C4A3s) decomposition; the use of high sulfur
content organic fuels that provide cement clinker a
SO3 content of 1.5 to 5% by weight; and sintering
temperature reduction. It is widely known that
alite formation temperature for a Portland cement
clinker is approximately of 2516°F, while calcium
sulphoaluminate decomposition temperature for a
white portland cement clinker is approximately
2462°F. Taking into account these criteria among
others, inventors have discovered that a new family
of white portland cement clinker compositions can
be obtained through the use of adequate
mineralogical phases (C3S, C2S, C3A, CS , C4A3S and
C11A7.CaF2) of cement clinker and through the
reduction of sintering temperature, using a high
sulfur content organic source, without having
problems associated to the use of said organic
source as fuel (for example, high sulfur content
pet-coke) which has a sulfur content higher than
5% .
White portland cement, prepared from the
above described clinker by fixing sulfur supplied
mainly by high sulfur content pet-coke (>5% S) , in
the form of calcium sulphoaluminate, C4A3s, exhibits
an excellent increase in the compression strength,
particularly it exhibits an accelerated development
of initial strengths, specially curing the interval
from 1 to 3 days. It is specifically referred to
the illustrative embodiments as follows:
Total content of SO3 in cement shall be
between 3 an 10% by weight obtained through the raw
meal calcination containing CaO, SiO2, Al2O3 and
CaF2, using pet-coke as fuel, with a sulfur content
higher than 5%, without the addition of any
additive containing SO3 in the raw meal.
A white Portland cement clinker can include
the following amounts from the clinker phases in %
by weight:
3CaO.SiO2 (C3S): 4O to 75,
2CaO.SiO2 (C3S): 10 to 35,
3CaO.Al2O3 (C3A): 0 to 15,
CaO.SO2 (Cs): 0 to 10,
4CaO.3Al2O3 . SO3 (C4A3s): 2 to 15,
HCaO. 7A12O3 . CaF2 (C11A7.CaF2) : 0 to 5,
Total %CaF2: 0.3 to 1.5 measured as CaF2,
%Fe2O3: 0 to 0.5,
And a SO3 content between 1.5 and 5% by
weight. Clinker is obtained through a raw meal
calcination containing CaO, SiO2, A12O3 and CaF2,
using pet-coke as fuel with a sulfur content higher
than 5% at temperatures between 2192°F to 2462°F
without the addition of any additive containing SO3
to the raw meal.
A cement clinker with percentages by weight
of the following clinker phases is preferred.
C3S: 40 to 75,
C2S: 10 to 35,
Cs: 0 to 10,
C4A3S: 5 to 15,
CnA7.CaF2: 2 to 5,
Total %CaF2: 0.3 to 1.5 measured as CaF2,
%Fe2O3: In another embodiment of the present
invention, a cement clinker with percentages by-
weight of the following clinker phases is more
preferred:
C3S: 40 to 75,
C2S: 10 to 35,
CS: 0 to 10,
C4A3S: 5 to 15,
Total %CaF2: 0.3 to 1.5 measured as CaF2,
%Fe2O3: Yet in another embodiment of the present
invention, a cement clinker with percentages by-
weight of the following clinker phases is more
preferred:
C3S: 40 to 75,
C2S: 10 to 35,
C3A: 5 to 15,
CS: 0 to 10,
C4A3S: 2 to 10,
Total %CaF2: 0.3 to 1.5 measured as CaF2,
%Fe2O3: Clinker calcination can be controlled to
produce specific amounts of C2S and C3A phases, such
as the addition of C2S and C3A clinker phases, and
must be higher or equal to 10% by weight.
Preferably C3A clinker phase is absent.
Clinker phase forming is eased through CaF2
percentage which is about 0.3 to 1.5 measured as
CaF2 in the raw meal. The preferred range is between
0.2 and 1.0% measured as CaF2 in the raw meal.
A preferred SO3 content in the clinker can
be indicated as 1.5 to 5% by weight, mainly
supplied through the organic fuel such as pet-coke
with a sulfur % higher than 5%. However, it is also
possible to optionally complement the S03 content in
the clinker with another inorganic sources selected
from the group consisting of plaster, anhydrite or
industrial debris containing sulfur.
Corresponding calcium sulphate can be used
to prepare finished white Portland cement.
To optimize setting reaction, according to
an embodiment, it is suggested that the clinker be
grinded in a specific area of 465 to 775 in2/g
measured according to the ASTM C-204 standard
through Blaine.
Forming a sulfur-rich phase, calcium
sulphoaluminate: 4CaO. 3A12O3. SO3 (C4A3S), shows an
accelerated development of initial strength
compared to those of Portland cement, due to C4A3S
hydration to form ettingite. Therefore, cements
according to the present invention with C4A3s
contents under 15% by weight, do not practically
exhibit any expansion, for which, said cement has
an initial strength exceeding that of a common
Portland cement.
On the other hand, during the clinker
calcination of the present invention, less melted
phase is formed (which is also due to the low
temperature of calcination), which drives to a
relatively porous clinker, in return, the clinker
has a better grinding capacity, and grinding costs
are reduced to the same specific area.
Particularly, another relevant advantage of the
clinker herein, is that alite and belite crystals
sizes are less than 25 micrometers, which provides
better grinding easiness than the conventional
white Portland cement clinker.
Clinker has a free lime percentage less
than 1.5%, this is, it shows a free lime content
similar to that of a white Portland cement clinker,
but sintered at 392°F under the traditional white
Portland clinker sintering temperature.
The present invention will be better
explained in detail based upon several examples.
However, following examples are provided only for
illustrative purposes, and it is not intended to
limit the scope of the present invention.
Sample 1 describes a cement free of C3A,
but comprises a 9% by weight of C4A3s and 4% by
weight of CuA7.CaF2.
Sample 2 describes a cement free of C3A and
C11A7.CaF2, but comprising a 12% by weight of C4A3s.
Sample 3 describes a cement free of
C11A7.CaF2, but comprising a 7% by weight of C3A and
3% by weight of C4A3S.
Percentages from other clinker phases, SO3
content in clinker, selected calcination
temperature, as well as the total of SO3 in cement
are shown in the table below, including compression
strength values measured after 1,3,7 and 28 days.
To illustrate the advantages that can be
obtained with cement of the present invention, a
conventional Portland cement, calcined at 2642°F,
is also shown as sample 4.
Data show that sample 2, according to the
present invention, exhibits a significant increase
on compression strength at all ages and samples 1
and 3, show comparable strength to those developed
by sample 4 which is the reference of white
Portland cement and calcined at 2642°F. Besides,
white portland cement of the present invention has
initial setting time from 10 to 45 minutes,
measured according to the ASTM C-191 standard
through Vicat.
In a particularly preferred embodiment of
the present invention, white portland cement
comprising clinker, which can be mixed with other
materials such as limestone, slag, fly ash and/or
puzolanic materials.
Even when certain embodiment of the present
invention has been illustrated and described, it
should be noted that numerous possible
modifications can be made. The present invention,
therefore, shall not be considered as limited
excepting for what the prior art demands and for
the spirit of the claims attached hereto.
We claim:
1. White Portland cement clinker, with the capacity to fix sulfur derived from an
organic fuel having a sulfur content greater than 5% S, used as a fuel in the calcination of
said clinker, said clinker additionally exhibiting reduced fuel consumption during such
calcination and useful for producing a fast setting cement, characterized in that said clinker
comprises amounts of clinker phases in percentage by weight, as follows:
3CaO.SiO2 (C3S): 40 to 75,
2CaO.SiO2 (C2S): 10 to 35,
3CaO.AI2O3(C3A):0 to 15,
CaO.SO3 (CS): 0 to 10,
4CaO.3AI2O3.SO3 (C4A3S): 2 to 15,
11CaO.7AI2O3.CaF2 (C11A7CaF2): 0 to 5,
%CaF2Total: 0.3 to 1.5 measured as CaF2,
%Fe2O3: 0 to 0.5,
and a SO3 content between 1.5 and 5% by weight obtained through the calcination
of a raw meal comprising CaO, SiO2, Al2O3 and CaF2, and using an organic fuel with a
sulfur content higher than 5% as the main source of the clinker's SO3 content, at
temperatures between 2192 °F and 2462 °F, without the addition of any SO3-containing
additive to the raw meal as a main source of SO3 content in the clinker.
2. The white Portland cement clinker as claimed in claim 1, wherein said clinker
comprises the amounts of clinker phases in percentage by weight, as follows:
3CaO.SiO2 (C3S): 40 to 75,
2CaO.SiO2 (C2S): 10 to 35,
CaO.SO3(Cs):0 to 10,
4CaO.3AI2O3.SO3 (C4A3S): 5 to 15,
11CaO.7AI2O3.CaF2 (C11A7CaF2,): 2 to 5,
%CaF2Total: 0.3 to 1.5 measured as CaF2,
%Fe2O3: and a SO3 content between 1.5 and 5% by weight obtained through the calcination
of a raw meal mainly containing CaO, SiO2, Al2O3 and CaF2, using as fuel pet-coke with a
sulfur content higher than 5%, at a temperature of 2282 °F, without any SO3-containing
additive to the raw meal as a main source of SO3 content in the clinker, wherein the
absence of C3A results in a clinker useful in the manufacture of cements resistant to
sulfates.
3. The white Portland cement clinker as claimed in claim 1, wherein said clinker
comprises the amounts of clinker phases in percentage by weight, as follows:
3CaO.SiO2 (C3S): 40 to 75,
2CaO.SiO2(C2S):10 to 35,
CaO.SO3(Cs): 0 to 10,
4CaO.3AI2O3.SO3 (C4A3S): 5 to 15,
%CaF2Total: 0.3 to 1.5 measured as CaF2,
%Fe2O3: and a SO3 content between 1.5 and 5% by weight obtained through the calcination
of a raw meal mainly containing CaO, SiO2, Al2O3 and CaF2, using as fuel pet-coke with a
sulfur content higher than 5%, at a temperature of 2282 °F, without any SO3-containing
additive to the raw meal as a main source of SO3 content in the clinker, wherein the
absence of C3A results in a clinker useful in the manufacture of cements resistant to
sulfates.
4. The white Portland cement clinker as claimed in claim 1, wherein said clinker
comprises the amounts of clinker phases in percentage by weight, as follows:
3CaO.SiO2 (C3S): 40 to 75,
2CaO.SiO2 (C2S): 10 to 35,
3CaO.AI2o3(C3A): 5 to 15,
CaO.SO3(CS): 0 to10,
4CaO.3AI2O3.SO3 (C4A3S): 2 to 10,
%CaF2Total: 0.3 to 1.5 measured as CaF2,
%Fe2O3: and a SO3 content between 1.5 and 5% by weight obtained through the calcination
of a raw meal mainly containing CaO, SiO2, Al2O3 and CaF2, using as fuel pet-coke with a
sulfur content higher than 5% as the main source of the clinker's S03 content, at a
temperature of 2462 °F, without any SO3-containing additive to the raw meal.
5. The white Portland cement clinker as claimed in claim 1, wherein the SO3
content of the cement clinker is derived from pet-coke with a sulfur percentage higher than
5%.
6. A white Portland cement comprising the cement clinker as claimed in claim 1,
mixed with at least one of other materials selected from the group consisting of lime, slag,
fly ash and other pozzolanic materials.
7. The white Portland cement clinker as claimed in claim 1, wherein the organic fuel
is pet-coke.
8. A method of producing a white Portland cement clinker as claimed in claim 7,
comprising the steps of:
subjecting a raw meal comprising CaO, SiO2, Al2O3 and CaF2, to a calcination at
temperatures between 2192 °F, and 2462 °F;
using pet-coke having a high sulfur content greater than 5% S as the calcination
fuel and as the main source of the clinker's SO3 content;
said raw meal having been mixed so as to form upon calcination a white Portland
cement clinker having phases in percentage by weight, as follows:
3CaO.SiO2 (C3S): 40 to 75,
2CaO.SiO2 (C2S): 10 to 35,
3CaO.AI2O3 (C3A): 0 to 15,
CaO.SO3(Cs): 0 to 10,
4CaO.3AI2O3.SO3 (C4A3S): 2 to 15,
11Ca0.7AI2O3.CaF2 (C11A7CaF2): 0 to 5,
%CaF2Total: 0.3 to 1.5 measured as CaF2,
%Fe2O3: 0 to 0.5,
and a SO3 content between 1.5 and 5% by weight, without the addition of any SO3-
containing additive to the raw meal as a main source of SO3 content in the clinker.
9. The white Portland cement clinker as claimed in claim 7, wherein the addition of
the amounts of C2S and C3A clinker phases is higher than or equal to 10% by weight.
10. The white Portland cement clinker as claimed in claim 7, wherein the total CAF2
percentage amount in the raw meal is from 0.2 to 1.0% by weight measured as CaF2.
11. The white Portland cement clinker as claimed in claim 7, wherein the clinker
SO3 content is supplemented with other inorganic sources selected from the group
consisting of plaster, anhydrite, and the industrial debris containing sulfur.
12. The white Portland cement clinker as claimed in claim 7, wherein the alite, C3S,
and belite, C2S, are crystals with sizes smaller than 25 micrometers, which provides a
better ease of grinding than the conventional white Portland cement clinker.
13. The white Portland cement clinker as claimed in any of claims 2 to 4 and 7,
wherein said clinker has a free lime percentage less than 1.5%.
14. A white Portland cement comprising the cement clinker as claimed in claim 7,
and wherein the SO3 content of said cement is between 3.0 and 10%.
15. The white Portland cement as claimed in claim 14, wherein the specific area is
465 to 775 in2/g measured according to the ASTM C-204 standard through Blaine.
16. The white Portland cement as claimed in claim 14, wherein the initial setting
time is between 10 and 45 minutes measured according to the ASTM C-191 standard
through Vicat.
17. The white Portland cement as claimed in claim 14, wherein the resistance to
compression measured according to ASTM C-109 is 15 to 25 N/mm2 at 1 day, 25 to 35
N/mm2 at 3 days, 40 to 44 N/mm2 at 7 days, and 50 to 70 N/mm2 at 28 days.
18. The white Portland cement as claimed in claim 14, wherein the SO3 content of
the cement is 3.5 to 10 wt. %.

The invention discloses a White Portland cement clinker, with the capacity to fix sulfur
derived from an organic fuel having a sulfur content greater than 5% S, used as a fuel in
the calcination of said clinker, said clinker additionally exhibiting reduced fuel consumption
during such calcination and useful for producing a fast setting cement, characterized in
that said clinker comprises amounts of clinker phases in percentage by weight, as follows:
3CaO.SiO2 (C3S): 40 to 75,
2CaO.SiO2 (C2S): 10 to 35,
3CaO.AI2O3(C3A): 0 to 15,
CaO.SO3(CS): 0 to 10,
4CaO.3AI2O3.SO3 (C4A3S): 2 to 15,
11CaO.7AI2O3.CaF2 (C11A7CaF2): 0 to 5,
%CaF2Total: 0.3 to 1.5 measured as CaF2,
%Fe2O3: 0 to 0.5,
and a SO3 content between 1.5 and 5% by weight obtained through the calcination
of a raw meal comprising CaO, SiO2, Al2O3 and CaF2, and using an organic fuel with a
sulfur content higher than 5% as the main source of the clinker's SO3 content, at
temperatures between 2192 °F and 2462 °F, without the addition of any SO3-containing
additive to the raw meal as a main source of SO3 content in the clinker.
The invention is also for a method of its production and white Portland cement comprising
it.

Documents:

614-kol-2003-granted-abstract.pdf

614-kol-2003-granted-assignment.pdf

614-kol-2003-granted-claims.pdf

614-kol-2003-granted-correspondence.pdf

614-kol-2003-granted-description (complete).pdf

614-kol-2003-granted-examination report.pdf

614-kol-2003-granted-form 1.pdf

614-kol-2003-granted-form 13.pdf

614-kol-2003-granted-form 18.pdf

614-kol-2003-granted-form 2.pdf

614-kol-2003-granted-form 3.pdf

614-kol-2003-granted-form 5.pdf

614-kol-2003-granted-gpa.pdf

614-kol-2003-granted-reply to examination report.pdf

614-kol-2003-granted-specification.pdf

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Patent Number

233684

Indian Patent Application Number

614/KOL/2003

PG Journal Number

14/2009

Publication Date

03-Apr-2009

Grant Date

01-Apr-2009

Date of Filing

05-Dec-2003

Name of Patentee

CEMEX TRADEMARKS WORLDWIDE LTD

Applicant Address

ROMERSTRASSE 13, 2555, BRUGG

Inventors:

#	Inventor's Name	Inventor's Address
1	GONZALEZ WALTTER LOPEZ	MISION LA PAZ # 6223 COL. MISION CUMBRES 64348, MONTERREY, NUEVO LEON, MEXICO
2	LINTON CARLOS ENRIQUE CASTILLO	MISION LA PAZ # 6223 COL. MISION CUMBRES 64348, MONTERREY, NUEVO LEON, MEXICO
3	MARQUEZ GRACIELA EGUIA	MISION LA PAZ # 6223 COL. MISION CUMBRES 64348, MONTERREY, NUEVO LEON, MEXICO

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	PA/a/2002/012235	2002-12-10	Mexico