JP2002542140A - Method for improving the grinding ability of cement aggregates - Google Patents

Abstract

  (57) [Summary] Prior to milling, the cement aggregate is treated at a temperature of from 250 ° C. to 1,000 ° C. in order to improve the millability of the cement aggregates, in particular slag, soot or pozzolan, and to adjust the hydraulic properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for improving the pulverizing ability of cement crushed materials, particularly slag, flue ash, or porazone, and adjusting hydraulic property.

[0002] Slag cement, in particular blast furnace slag cement or metallurgical cement, is obtained from slag that has been granulated by grinding and is usually used as a grinding material for cement mixtures. It is known that chemicals, in particular so-called grinding additives, improve the grindability during grinding. However, such components are foreign substances in the milled material. It is likewise known that chemicals added to the cement or during the production of concrete affect the hydraulic properties, in particular the performance of the setting and the compressive strength at a given point in time.

The present invention aims at improving and / or affecting the grindability, and optionally the hydraulic properties, of cement grinds without any such chemical aids. To this end, the method according to the invention consists essentially of subjecting the cement grind to a temperature treatment between 250 ° C. and 1000 ° C. before the grinding. Surprisingly,
In particular, it has been found that the granulated blast furnace slag exhibits significantly enhanced fracture-mechanical properties after such temperature treatment. The change in such a case essentially comes from the so-called glass relaxation temperature to the crystallization temperature, where the required grinding energy is reduced by about 20% by treatment at about 500 ° C. for about 1 hour. It was shown to be. Surprisingly, it has been found that changes in hydraulic properties, especially strength, can be significantly affected in this temperature range where the required grinding energy can be reduced by thermal treatment. Treatment of the blast furnace slag granules at a temperature of about 500 ° C reduces the grinding power consumed by about 20% while increasing the compressive strength on day 28 by about 15%. Processing at relatively high temperatures, especially for example about 900
Treatment at 0 ° C. reduced the grinding energy relatively significantly, which also made it possible to reduce the grinding energy by half. However, here, such a treatment at a temperature of about 900 ° C. reduced the compressive strength after 7 and 28 days. Thus, the reduction in the grinding energy consumed is not linearly related to the change in compressive strength and the change in hydraulic properties with increasing processing temperature, and thus also the delay in setting of the cement mixture in some cases. Still considered desirable. Such a cure in a conventional manner could only be obtained by chemicals.

[0004] Advantageously, the method of the invention provides that the temperature treatment is from 300 ° C. to 900 ° C., in particular from 300 ° C.
700 ° C., whereby blast furnace slag treated at such a temperature is mixed with Portland cement in a 1: 1 ratio after or during the milling process in this temperature range. Of the crushing energy of the crushing agent by about half and increasing the compressive strength after 28 days in the preferred temperature range by 20%.
%. Furthermore, the improvement of the crushing ability of the processing component also results in the improvement of the crushing ability of the mixture of the Portland cement clinker and the treated blast furnace slag granules.
The grinding energy consumed is reduced, or highly fine grinding can be performed with the same grinding energy.

In a particularly advantageous manner, the process according to the invention carries out the temperature treatment for a period of from 15 minutes to 3 hours, in particular from 45 minutes to 2 hours. Especially when using blast furnace slag, the temperatures generally required for temperature treatment can be obtained in the form of waste heat in the blast furnace reach. At relatively high processing temperatures, a relatively short processing time can be selected. Thus, for example, the residual heat of a blast furnace regenerator can be used. The temperature treatment itself can be carried out in various places, which is advantageously carried out by delaying the cooling, taking advantage of the residual heat of the granulated particles, and immediately after the granulation, by performing a heat treatment immediately after the slag treatment. The selective influence of the quality of the granulation and the reduction of the grinding operation can be obtained by a simple adaptation of the standard granulation or pelletizing process, in particular by adjusting the residence time during dry granulation and by controlling the temperature. However, blast furnace slag can also be substantially improved by introducing it into a drying plant for thermal after-treatment. Finally, for example,
A separate processing unit is located upstream of the slag attritor, and the waste heat from the clinker cooling means and the other option provided in the area of the cement rotary cylindrical kiln clinker cooler are used simultaneously to make the blast furnace slag Can be considered to be in a temperature range suitable for such treatment. Finally, the grinding temperature may increase during blast furnace slag grinding.

[0006] The improved grinding capacity of the blast furnace slag components, along with the potential for more economical grinding when combined with clinker and slag, and the favorable effect on the initial strength of the concrete, The possibility exists to modify and adapt the characteristic strength changes of the cement. At the same time, for example, it is possible to decrease the strength on day 28 and increase the initial strength. The manner of such a process can be ensured by an improved grinding capacity, in particular by an increased slag fineness due to the combined grinding of slag and clinker.

In a particularly simple manner, the cement grind can be air-cooled after the heat treatment and before the grinding treatment, the treatment of the blast furnace slag being carried out at a temperature below the metal crystallization temperature of about 850 ° C. Is preferred.

According to a preferred further mode, the nucleation temperature is between 250 ° C. and about 700 ° C., in particular about 5 ° C.
A particularly significant increase in strength values is observed when heat treatment is performed at 00 ° C.

Hereinafter, the present invention will be described in more detail with reference to the drawings. Here, FIG. 1 shows a change in compressive strength after temperature treatment, FIG. 2 shows a change in bending strength at different treatment temperatures, and FIG. This indicates a decrease in grinding energy.

With reference to the exemplary embodiment shown in the figures, a series of further measurements were made. Here, in particular, thermoanalytical measurements of the nucleation and crystallization temperatures of the mainly provided metallic phases, each measurement of the crushing fineness of Blaine by sieving analysis or laser diffraction, and a slag fraction of 50%, WC Each measurement of hydraulic activity according to Australian Standard B3310 using a mortar column with a value (water value for cement) of 0.6 was performed. Standard control tests show that intensity changes are adversely affected after completion of nucleation; negative intensity changes after completion of nucleation indicate changes in vitreous components in standard control diffractometer measurements. Not at all. The test was performed in a step of 100 ° with respect to the processing temperature, and the results are shown in FIG. FIG. 1 shows the change in compressive strength for different treatment temperatures with a slag to cement ratio of 50:50. In FIG. 1, the change in strength, especially the improvement in strength on day 28,
It has been shown to be significant at temperatures in the range of 400-600 °. However, the measurement point at 900 ° C. should not be considered as representative in the description of FIG. This is because, in this test, the 4500 cm ² /
This is due to the fact that a certain fineness of g is not observed due to a substantially improved grinding power. The considerably enhanced grinding power in this case resulted in a fineness of 6700 cm ² / g.

The thermal analysis of blast furnace slag shows that the peak temperature of nucleation is 710 ° C., the metal crystallization temperature is 850 ° C., further crystallization occurs at 900 ° C., and the eutectic peak temperature is 1
, 190 ° C. Uniform melting in the thermal analysis was observed at 1,330 ° C.

The blast furnace slag was treated in a chamber kiln. Here, the processing time was set to 1 hour at the temperature shown in FIG. After this treatment time, the slag was removed from the kiln and air cooled.

The blast furnace slag thus treated was pulverized in a ball mill, and the degree of pulverization was evaluated by measuring the fineness of the Blaine.

From the change in compressive strength shown in FIG. 1, a significant increase in compressive strength in the temperature range up to about 500 ° C. is evident. Maximum compressive strength after 28 days is achieved at a temperature higher than the temperature at which the initial strength is maximized. Thus, the temperature treatment changes the strength value at a given point in time, whereby the hydraulic properties can be adjusted over a wide range.

Above the nucleation and crystallization temperatures (approximately 700 ° C.), a decrease in hydraulic activity, especially the compressive strength on day 28, was observed. Surprisingly, the increase in compressive strength on day 2 can also be observed at relatively high temperatures.

As already mentioned, the measurement points at 900 ° C. in FIG. 1 should not be considered as good examples. This is due to the fact that, in this case, pulverization is carried out which results in a substantially high degree of micronization.

The temperature treatment can also have a clear effect on the flexural tensile strength. FIG. 2 again shows the change in flexural tensile strength at different treatment temperatures for a 50:50 ratio of slag cement. Here, regarding the fineness of the pulverization,
The same description as above applies again at the measurement point at 900 ° C. In this figure,
Up to the crystallization temperature, the flexural strength tends to decrease slightly, and immediately above the crystallization temperature, there is a clear decrease in flexural strength.

[0018] The flexural tensile strength and the compressive strength in the initial strength range show similar changes.
Thus, it can also be adapted considerably to the desired hydraulic properties of the final product.

Finally, the grindability at the temperatures tested was measured. The result is shown in FIG. From FIG. 3, the change in the milling time as a function of the applied processing temperature is clear, about 4
It is clearly shown that the milling time until the same brane fineness of 500 cm ² / g is achieved is rapidly reduced by increasing the processing temperature. The measurements for the temperature of 900 ° C. in this case are not completely accurate. This is because at this point a crushing fineness of 6,700 cm ² / g has already been achieved, and a Blaine fineness of 4,500 ² cm / g has already been achieved at a substantially faster point in time. . The fineness of the grinding was additionally confirmed by examining the residue (R45) on the 45 μm sieve (and by laser diffraction measurements). The results of such measurements are shown in the table below.

[Table 1]

As shown by the measurement of R45 and the measurement of the particle size distribution by laser diffraction, the increased crystalline material fraction is accompanied by a distinct change in the particle size distribution characteristics of the slag.

[0021] Therefore, at temperatures between 300 and 500 ° C., already about 15 grinding energy savings have been achieved. A reduction of about 20% is obtained in the nucleation temperature range, and once the crystalline fraction has formed, the grinding time is again significantly reduced.

[Brief description of the drawings]

FIG. 1 shows the change in compressive strength after temperature treatment.

FIG. 2 shows the change in bending strength at different processing temperatures.

FIG. 3 shows the reduction in required grinding energy at various temperature treatments.

[Procedure amendment]

[Submission date] June 18, 2001 (2001.6.18)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Contents of correction]

With reference to the exemplary embodiment shown in the figures, a series of further measurements were made. Here, in particular, thermoanalytical measurements of the nucleation and crystallization temperatures of the mainly provided metallic phases, each measurement of the crushing fineness of Blaine by sieving analysis or laser diffraction, and a slag fraction of 50%, WC Each measurement of hydraulic activity according to Australian Standard B3310 using a mortar column with a value (water value for cement) of 0.6 was performed. Standard control tests show that intensity changes are adversely affected after completion of nucleation; negative intensity changes after completion of nucleation indicate changes in vitreous components in standard control diffractometer measurements. Not at all. The test was performed at a process temperature of 100 ° C. , and the results are shown in FIG. FIG.
The slag to cement ratio of 50:50 shows the change in compressive strength for different treatment temperatures. FIG. 1 demonstrates that the change in strength, particularly the strength improvement at day 28, is significant at temperatures in the range of 400-600 ° C. However, the measurement point at 900 ° C. should not be considered as representative in the description of FIG. This is in this test the 4500 cm ² observed in other tests.
/ G is not observed due to substantially improved milling power. The considerably enhanced grinding power in this case resulted in a fineness of 6700 cm ² / g.

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Claims (7)

[Claims] 1. Prior to the pulverizing treatment, pulverizing material for cement, especially slag, flue ash,
Alternatively, a method for improving the pulverizing ability of a pulverized material for cement and adjusting hydraulic property, which comprises subjecting pozzolan to a temperature treatment at 250 to 1,000 ° C. 2. The temperature treatment is performed at a temperature of 300 ° C. to 900 ° C., particularly 300 ° C. to 700 ° C.
The method according to claim 1, wherein the method is performed at a temperature of ° C. 3. The method according to claim 1, wherein the temperature treatment is performed for 15 minutes to 3 hours, preferably for 45 minutes to 2 hours. 4. The method according to claim 1, wherein the pulverized cement material is air-cooled after the temperature treatment and before the pulverization treatment. 5. The method according to claim 1, wherein the treatment of the blast furnace slag is performed at a temperature lower than a metal crystallization temperature of about 850 ° C. 6. The method according to claim 1, wherein the heat treatment is carried out at a nucleation temperature in the range from 250 ° C. to about 700 ° C., in particular at about 500 ° C. 7. The method according to claim 1, wherein the heat treatment is performed immediately after the granulation by delayed cooling using the residual heat of the granulated particles.