Patent Application
20120285350
1. Field of the Invention
The present invention relates to the preparation process of high cementitious cement clinker, more specifically, it relates to secondary synthetic method of calcium sulphoaluminate in Portland cement clinker.
2. Description of the Related Art
The key issue in the preparation of Portland cement clinker containing C4A3
However, at present, most of cement is prepared via dry calcination in China, where the calcination temperature is around 1450° C. As a result, most of the C4A3
An object of the present invention is to improve the calcining process of Portland cement clinker containing C4A3
To realize above mentioned object, the technical scheme of present invention is a secondary synthetic method for calcium sulphoaluminate mineral in Portland cement clinker, where the method comprises the following steps:
In alternative embodiments, a secondary synthetic method for calcium sulphoaluminate mineral in Portland cement clinker consists of the following steps:
Preferably, the holding time of steps (2), (3), (2A) and (3A) is 5˜120 min, respectively. Preferably, the specific surface area of grounded powder of steps (4) and (4A) is 340˜360 m2/kg.
Calcination of the prepared raw meal in steps (2) and (2A) is carried out under regular processing parameters.
The present invention relates to the thermal treatment of Portland cement clinker containing calcium sulphoaluminate mineral. Through the thermal treatment, calcium sulphoaluminate mineral which has been decomposed at high temperature is reformed, Thus the content of calcium sulphoaluminate mineral in the cement clinker is improved and the function of calcium sulphoaluminate mineral in Portland cement clinker is brought into full play. As a result, the short-term and long-term properties of cement clinker are improved and the doping amount of composite material in the resultant_cement is increased.
The present invention is further illustrated with reference to the following examples. However, it may be understood that the present invention is not limited to the following examples.
(1) 0.30 kg gypsum (the SO3 content in gypsum is 32.90 wt %) was added as a dopant to 5 kg of a prepared Portland cement raw meal (the chemical compositions of cement raw meal are shown in Table 1). As a result, the SO3 content in raw meal was 1.86 wt %.
(2) The prepared cement raw meal was heated to 1480° C., calcined for 30 min, and cooled. Subsequently, the temperature was increased to 1450° C. at a rate of 5° C. per minute, kept at this temperature for 30 min, and then was cooled.
(3) The cooled cement clinker was increased at a rate of 10° C. per minute until it reached 1200° C., kept at this temperature for 60 min, and then was cooled.
(4) The cooled cement clinker was grounded to powder with the aid of ball mill, where the specific surface area of the powder was 350 m2/kg. According to the test method disclosed in CN200710302594.1, the entirety of which is incorporated by reference, it was determined that the C4A3
(5) 4 g gypsum was added to 96 g of the cement clinker obtained according to the method disclosed above. The mixture was subsequently mixed uniformly, 29 mL of water (ratio between water and cement w/c=0.29) was added and the mixture was stirred and molded to 20×20×20 mm samples from which the 1d, 3d and 28d compressive strength could be determined. Samples were first cured in a curing case for 24 h, where the relative humidity was 90% and the temperature was 20±2° C. Then the demolded sample was cured in a water curing case at 20±1° C. The comparison of resulting strength is shown in Table 2.
(1) 0.28 kg gypsum (the SO3 content of gypsum is 32.90 wt %) was added to 5 kg of a prepared Portland cement raw meal (the chemical compositions of cement raw meal are shown in Table 1). As a result, the SO3 content of raw meal was 1.74 wt %;
(2) The prepared cement raw meal was heated to 1450° C., calcined for 60 min and cooled. Subsequently, the temperature was increased to 1400° C. at a rate of 10° C. per minute, kept at this temperature for 50 min, and then cooled.
(3) The temperature of the cooled cement clinker was increased at a rate of 15° C. per minute until it reached 1250° C., kept at this temperature for 90 min, and then cooled.
(4) The cooled cement clinker was grounded to powder with the aid of a ball mill, where the specific surface area of the powder was 360 m2/kg.
(5) 4 g gypsum was added to 96 g of the cement clinker formed according to the above described process. The mixture was mixed uniformly and, subsequently, 29 mL water (ratio between water and cement w/c=0.29) was added. The mixture was stirred and molded to 20×20×20 mm samples from which the 1d, 3d and 28d compressive strength could be determined. Samples were first cured in a curing case for 24 h, where the relative humidity was 90% and the temperature was 20±2° C. Then the demolded sample was cured in a water curing case at 20±1° C. The comparison of resulting strength is shown in Table 3.
(1) 0.3 kg gypsum (the SO3 content of gypsum is 32.90 wt %) was added to 5 kg of a Portland cement raw meal (the chemical compositions of cement raw meal are shown in Table 1). As a result, the SO3 content of raw meal was 1.86 wt %.
(2) The prepared cement raw meal was heated to 1450° C. calcined for 60 min and cooled; subsequently, the temperature was increased to 1450° C. at a rate of 5° C. per minute and kept at said temperature for 30 min, and then it was transferred to a cooler, the temperature was reduced at a rate of 55° C. per min.
(3) The temperature was cooled to 1250° C., and kept at said temperature for 60 min, and then it was cooled again.
(4) The said cooled cement clinker was grounded to powder with the aid of ball mill, the specific surface area of said powder is 340 m2/kg.
(5) 4 g gypsum was added to 96 g final obtained cement clinker, the said mixture was mixed uniformly, subsequently, 29 mL water (ratio between water and cement w/c=0.29) was added, the said mixture was stirred and molded to 20×20×20 mm samples, and the 1d, 3d and 28d compressive strength was determined. Samples were first cured in a curing case for 24 h, wherein the relative humidity was 90% and the temperature was 20±2° C., and then the demolded sample was cured in a water curing case at 20±1° C. The comparison of resulting strength is shown in Table 4.
(1) 0.28 kg gypsum (the SO3 content of gypsum is 32.90 wt %) was added to 5 kg of a Portland cement raw meal (the chemical compositions of cement raw meal are shown in Table 1). As a result, the SO3 content of raw meal was 1.74 wt %.
(2) The prepared cement raw meal was heated to 1450° C., calcined for 60 min and cooled. Subsequently, the temperature was increased to 1400° C. at a rate of 10° C. per minute, kept at this temperature for 50 min, and then it was transferred to a cooler, where the temperature was reduced at a rate of 50° C. per min to 1200° C.
(3) The temperature was kept at this temperature for 30 min, and then it was cooled.
(4) The cooled cement clinker was grounded to powder with the aid of ball mill, where the specific surface area of the powder was 340˜360 m2/kg.
(5) 4 g gypsum was added to 96 g of the cement clinker obtained according to the method disclosed above. The mixture was mixed uniformly and, subsequently, 29 mL water (ratio between water and cement w/c=0.29) was added. The mixture was stirred and molded to 20×20×20 mm samples from which the 1d, 3d and 28d compressive strength could be determined. Samples were first cured in a curing case for 24 h, where the relative humidity was 90% and the temperature was 20±2° C. Then the demolded sample was cured in a water curing case at 20±1° C. The comparison of resulting strength is shown in Table 5.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200910212645.0 | Nov 2009 | CN | national |
This Application is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/CN2010/075188, filed Jul. 15, 2010, which was published in Chinese as International Publication No. WO/2011/057506 on May 19, 2011, and claims the benefit of CN 200910212645.0, filed on Nov. 13, 2009. Each of these references is hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN10/75188 | 7/15/2010 | WO | 00 | 5/14/2012 |
