JP2002097043A - Method of producing blast furnace slowly cooled slag sand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sand having quality equal to or more than that of natural sand from blast furnace slowly cooled slag which is of less practical use at present. SOLUTION: The method of producing blast furnace slowly cooled slag sand using the blast furnace slowly cooled slag having apparent specific gravity of 2.40 or more, preferable 2.45 or more and particle diameter of 2-7 mm, preferably 3-5 mm as a raw material, this raw material is crushed and is then subjected to frictional crushing which makes crushed materials rub against each other, and thereafter is classified after dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing sand having a quality equal to or higher than that of natural sand from blast furnace slag.

[0002]

2. Description of the Related Art Slowly cooled blast furnace slag obtained by gradually cooling molten slag discharged from a blast furnace has a time required for the structure to stabilize (crystallize) and does not have hydraulic properties even when water and calcareous are added. As in the case of the aggregate, it is crystalline and shows the same hardness. The blast furnace slow cooling slag is mainly used for roadbed materials, harbor landfill materials, coarse aggregate for concrete, and the like. However, there is almost no record as fine aggregate for concrete or mortar. The reason is due to a shape defect. That is, it is not round but square as compared with natural river sand or sea sand, and when used as fine aggregate, it becomes concrete or mortar with poor workability.

[0003]

As described above, at present, blast furnace slow-cooled slag cannot be used as a substitute for natural sand due to its poor shape. The purpose is to perform processing to make the shape closer to a sphere.

[0004]

In order to achieve the above object, a method for producing blast furnace slow-cooled slag sand of the present invention comprises an apparent specific gravity of at least 2.40, preferably at least 2.45, and a particle size of 2 to 7 mm.
Preferably, a method is used in which a blast furnace slow-cooled slag of 3 to 5 mm is used as a raw material, this raw material is crushed, a crushing process is performed in which the crushed raw materials are rubbed with each other, then dried and then classified.

[0005] In this grinding process, the water content of the raw material is 2-5.
It is preferable to carry out in a wet state of weight% because the grinding effect is higher than in a dry state. That is,
When the water content is less than 2% by weight, prewetting is better, and when it exceeds 5% by weight, the water film covers the particles, which may hinder the rubbing action between the particles. Therefore, the water content is preferably 2 to 4% by weight.

Here, the apparent specific gravity of the blast furnace slowly cooled slag as a raw material is set to 2.40 or more. If the apparent specific gravity is less than 2.40, there are many bubbles inside the particles, and even if the outer periphery becomes round like natural sand, bubbles are generated. It is because the trace cannot be eliminated.

The reason why the particle size of the raw material is 2 to 7 mm is as follows.
If the ratio is out of this range, the effect of improving the grain shape is poor, and a concentricity comparable to that of natural sand cannot be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below for the understanding of the present invention. The raw material was crushed with a roll crusher type light crusher while changing the roll interval in two stages to obtain two types of raw sand having different particle size compositions. Table 1 below shows the results of determining the average concentricity by particle size of the raw sand.
Note that FM in Table 1 indicates a coarse particle ratio (the same applies hereinafter).

[0009]

[Table 1]

[0010] Determination of where heart circle ratio, area measurement of a particle projection photographing view by computer Microscope: Amm 2 ^· particles measuring the maximum diameter of the projection imaging Figure: the L mm - Amm ² and Kokoroen the radius Find: Rmm = √A /
√π ・ N = 10 measurements with the same particle diameter are performed to determine the average circularity. Concentricity (%) = R / 0.5L × 100

The effect of improving the shape when the two types of raw sand shown in Table 1 were subjected to grinding such as rubbing the raw materials with each other using a cylindrical rotary sliding grinder was evaluated by the circularity. The results obtained and evaluated are shown in Table 2 below. The angle in Table 2 is the angle formed by the side wall of the rotary grinding machine below the water surface (the same applies hereinafter).

[0012]

[Table 2]

[0013] Table 3 below shows the results of obtaining and comparing the improvement rates of the concentricity.

[0014]

[Table 3]

Table 4 below shows the results of a mortar strength test (cement: sand: water = 1: 2: 0.65) for confirming the effectiveness as an aggregate.

[0016]

[Table 4]

As can be seen from Table 3, the angle formed by the side wall of the grinder with the horizontal plane during grinding is 55 to 90 degrees rather than 90 degrees.
Degrees are preferred, and the results of other tests indicate that the angle is between 45 and 45.
It turned out that 60 degrees, preferably 50 to 55 degrees is good. That is, if the angle is less than 45 degrees, the circularity decreases, and if it exceeds 60 degrees, a dead space is likely to occur.

[0018]

As has been described above, according to the method of the present invention, it is possible to produce a blast furnace slowly cooled slag having a quality equal to or higher than that of natural sand from a blast furnace slowly cooled slag which is currently not used very effectively. As a result, it is possible to effectively utilize unused resources and to prevent the natural destruction caused by the extraction of natural sand. And if it is blast furnace slowly cooled slag sand according to the present invention, for example, even if used as mortar sand,
It may be used as sand for ready-mixed concrete, or because it is crystalline sand, unlike vitreous granulated slag sand, its particle strength and stability against heating are high, so it may be used as molding sand. It is something that can be done.

Claims (4)

[Claims] 1. An apparent specific gravity of 2.40 or more and a particle size of 2 to 7 mm.
The blast furnace slow cooling slag is used as a raw material, this raw material is crushed, and then the crushed raw material is subjected to grinding processing to rub each other,
A method for producing blast furnace slow-cooled slag sand, which is followed by drying and classification. 2. The method for producing blast furnace slow-cooled slag sand according to claim 1, wherein the blast furnace slow-cooled slag having an apparent specific gravity of 2.45 or more is used as a raw material. 3. The method for producing slowly cooled blast furnace slag sand according to claim 1, wherein the blast furnace slowly cooled slag having a particle size of 3 to 5 mm is used as a raw material. 4. A method for producing slowly cooled blast furnace slag sand according to claim 1, wherein the grinding process is performed in a wet state of the raw material.