JPS602262B2 - Method for producing granulated slag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing granulated slag suitable as fine aggregate for concrete mortar.

Along with the development of the steel manufacturing industry, the amount of molten blast furnace slag produced in Toyama from blast furnaces has also increased, but while some of it is effectively used for cement, the majority of it is difficult to dispose of. It is.

Conventionally, two methods have been used to treat such molten blast furnace slag. One of these methods is to discharge molten blast furnace slag onto a vast site, allow it to cool naturally, then dig it up with a bulldozer or the like, crush it into appropriate sizes, and use it as ballast. Another method is to inject water into the molten slag and crush it into so-called granulated slag with a diameter of 5 or less, which is used as a raw material for blast furnace cement. By the way, it has been a long time since it was pointed out that there was a shortage of natural sand for concrete and mortar used in the fields of architecture and civil engineering.
Therefore, research into artificial sand as an alternative to natural sand is active, and the application of blast furnace slag in this field is also being considered. However, the above-mentioned method of manufacturing ballast mainly yields large particles, which must be crushed in order to be used as pongee aggregate, but ballast has extremely high strength. It is extremely difficult and uneconomical to crush to a particle size suitable for fine aggregate (5 sides or less). In addition, since most of the granulated slag has a particle size of 5 ribs or less in diameter, it is suitable for small bone villages, but because it is soft and coarsely glassy, it is used as pongee aggregate. However, there are problems with strength, specific gravity, water absorption, etc., and it is inappropriate. The present inventors conducted research aimed at using molten blast furnace slag mainly as pongee aggregate, and as a result,
We determined that the most appropriate method is to add additives to granulated slag during the manufacturing process to make it heavy and granular.
The present invention has been achieved in which a metal sulfate such as gypsum or a metal sulfite such as calcium sulfite is used as the additive.

That is, the present invention adds at least one additive selected from the group consisting of metal sulfates and metal sulfites to molten blast furnace slag, and the time from the addition of the additive until granulation is determined by the additive. This is a method for producing granulated slag, characterized by pulverizing molten blast furnace slag for the minimum time required to substantially dissolve it into molten blast furnace slag.

Examples of additives used in the present invention include gypsum, sodium sulfate, iron sulfate, metal sulfates such as steel sulfate, calcium sulfite,
Examples include metal salts such as sodium sulfite, which may be used alone or in combination of two or more.

Particularly preferred additives are gypsum, and examples of the gypsum include dihydrous gypsum (CaS04, 2 days 20), semihydrous gypsum (CaSC4, 1/20), dead-fired gypsum (CaS
04) may be used, and may be dry or wet. In particular, it is possible to use desulfurized gypsum and desulfite scales obtained from flue gas desulfurization processes.
It is desirable that the additive material be in the form of a powder or granules of less than 1 ship size. It has been found that metal sulfates and sulfites, such as gypsum, are useful for making granulated slag heavy, but only when the dissolution time in molten blast furnace slag is short.
That is, if the time from the addition of the additive until granulation is the minimum time required for the additive to almost completely melt into molten blast furnace slag, for example, the addition of 5% gypsum will result in a specific gravity of 0. 6 (90%), and customer weight improved by 0.7 (70%). This heavy granulated slag has a high customer weight and specific gravity,
The water absorption rate is 4. There are many coarse particles and the circularity has improved.
This is a desirable physical property of aggregate. In addition, if the dissolution time of additives in molten blast furnace slag is increased,
Contrary to the above, the specific gravity decreases by 0.4 (20%) when 5% gypsum is added, and the passenger car becomes lighter by 0.3 (30%).
%)descend. This lightened granulated slag is useful as a nutrient soil material for plant cultivation and as a soil improvement material. The dissolution time of additives such as gypsum, which separates the difference between lightening and lightening, is about 10 minutes.

The results of an experimental study of the relationship between this dissolution time and each physical property are illustrated. Figure 1 shows the fineness (absolutely dry apparent specific gravity/
(true specific gravity), Figure 2 shows the water absorption rate, and Figure 3 shows the coarse particle ratio, in both of which the solid line shows the case where the melting time is less than 10 minutes, and the dotted line shows the case where the melting time is 20 minutes or more.

In both cases, extreme differences in trends are seen within the range of gypsum addition rates of 1 to 5%. Generally, the addition rate of the additive may be within the range of 0.5 to 10% by weight based on the molten blast furnace slag, but in the case of gypsum, best results are obtained with addition of 1 to 5%.

It is not clear why the addition of additives such as slag is effective in making the granulated slag granulated, but if the dissolution time is lengthened to make it lighter, the same amount of effect as the addition of calcium sulfide can be obtained. Therefore, it is thought that as the dissolution time increases, calcium sulfide is formed, and lightening occurs due to its reducing action. The present invention makes it possible to produce granulated slag that is useful as fine aggregate or ground improvement material by simply adding additives such as slag, which are easily available, and adjusting the time, thereby making it possible to use resources efficiently. This invention is useful both from the standpoint of utilization and the scarcity of scarce resources.

Next, examples will be described.

Example 1 Dry granulated blast furnace slag having the composition shown in Table 1 was mixed with 5% by weight of various additives, and this mixture was placed in a carbon rubbo and heated and melted in a high frequency electric furnace.

The melting temperature was set to 1500q0, the molten slag was introduced into a granulation test device, the blowing water pressure was 2k9/ground, and the water noslag ratio was 10.
It was pulverized at a water temperature of 80 qo. In addition, for comparison, a blank test without additives was conducted under the same conditions. Table 2 shows the experimental results. Since it takes about 20 minutes for the slag to completely dissolve, each sample in Table 2 was held at 1500 oo for 5 to IQ minutes after being dissolved. Table 1 (unit weight) C Si02A and 203 breasts F30Mn203 r
i02 S41.8 32.7 14.6 6.0
22 05 1.4 1.0 Table 2 Examples
2 In a test similar to Example 1, only the slag was dissolved (
(Dissolution time: 40 minutes) Then, 0 and 1 were added to the raw slag, respectively.
Figure 1 shows the fineness of the granulated slag obtained by adding and mixing 3.5% by weight of Setsukou (CaS041 20), Figure 2 shows the water absorption rate, and Figure 2 shows the coarse particle ratio. Shown in Figure 3.

The solid line indicates the retention time after addition until granulation, which is less than 1 night, and the dotted line indicates the retention time after addition until granulation.
This is the case when the amount exceeds the Example 3 In a test similar to Example 2, 5% by weight of Iso gypsum was added to the molten slag instead of gypsum, and the granulated slag was left to stand and then granulated, resulting in a granulated slag with a fineness of 0. .87, water absorption rate was 2.2%, and coarse particle rate was 4.05.

[Brief explanation of drawings]

Figures 1 to 3 are graphs showing the test results of the present invention, with Figure 1 relating to fineness, Figure 2 relating to water absorption, and Figure 3 relating to coarse grain ratio. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Adding at least one additive selected from the group consisting of metal sulfates and metal sulfites to molten blast furnace slag,
The granulated slag is characterized in that the molten high-density slag is granulated by setting the time from the addition of the additive to the granulation as the minimum time necessary for the additive to be substantially dissolved in the molten blast furnace slag. Production method. 2 The amount of additive added is 0.1 to 1 to molten blast furnace slag.
The method for producing granulated slag according to claim 1, wherein the content is 0% by weight. 3. The method for producing granulated slag according to claim 1, wherein the additive is slag. 4. The method for producing granulated slag according to claim 3, wherein the amount of slag added is 1 to 5% by weight based on the molten blast furnace slag.