JPH05262542A - Utilization of ferroalloy slag - Google Patents

Abstract

PURPOSE:To utilized ferroalloy slag as a concrete aggregate by mixing the ferroalloy slag which is air-crushed into spherical particles of less than prescribed size with sand at a specific ratio. CONSTITUTION:Ferroalloy slag (for example, ferrochromium slag) is air-crushed into spherical particles of less than 5mm diameter is utilized as a concrete aggregate by mixing with sand at a volume ratio of 7/3 to 4/6, or further, with a combination of water-reducing admixture and thickeners, to increase the concrete strength and maintain high fluidity despite the reduced water volume. Thus, the mold frames can be readily filled with the concrete by no use of vibrators, resulting in increased initial strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for utilizing ferroalloy slag, which is a method for effectively utilizing ferroalloy slag produced as a by-product during the production of ferroalloy.

[0002]

2. Description of the Related Art Ferroloy slags are mostly of low utility value and have been landfilled as industrial waste.
Also, some of them are only slightly used for roadbeds.

[0003]

The landfill disposal of ferroalloy slag has many problems in terms of securing the landfill site, landfill cost, and effective use of resources.

The present inventors have examined the use of ferroalloy slag as a part of concrete. Among conventional aggregates for concrete, coarse aggregate was mainly round river gravel, and fine aggregate was mainly similar river sand, and the actual volume ratio was good, and the flowability was fairly good, but
Since the collection of river gravel and river sand is prohibited, crushed stone and crushed sand are mainly used, and the actual volume and fluidity are poor.

Therefore, various efforts have been made such as increasing the water-cement ratio and increasing the cement content.
That is, concrete is cast by adding coarse aggregate, fine aggregate and water to cement (in some cases, adding water reducing agent, fly ash, granulated blast furnace slag powder, etc.), kneading with concrete mixer, etc. It is poured into and filled with a vibrator or the like.

However, if the mixing ratio of water in the concrete is increased in order to improve the filling property, in other words, the fluidity, the compressive strength of the concrete is lowered. Further, when the mixing ratio of water is reduced, the compressive strength of concrete rises to some extent, but the fluidity of concrete decreases, so that the filling becomes insufficient and the compressive strength decreases.

[0007] In recent years, while work related to civil engineering and construction has been increasing, there is a general tendency for these works to be shunned, and there is a shortage of workers. There is a problem that it causes trouble.

The present inventors utilize ferroalloy slag, which has not been used so far, as an aggregate for concrete, thereby effectively utilizing the unused ferroalloy slag, and further improving the efficiency of concrete placing work. It is to plan.

[0009]

[Means for Solving the Problems] The first invention is a diameter of 5 mm.
Use of ferroalloy slag, which is crushed and spheroidized as below, as an aggregate for concrete, and in which the volume ratio of sand: ferroalloy slag is mixed in the ratio of 7: 3 to 4: 6. Is the way.

A second aspect of the present invention is a method for utilizing ferroalloy slag, which comprises using spheroidized ferroalloy slag in combination with a spheroidized ferroalloy slag and a water-reducing agent and a thickener when using the spheroidized ferroalloy slag as an aggregate for concrete. is there.

In addition, ferroalloy slag refers to ferrochrome slag, ferro nickel slag, silico manganese slag, and ferro manganese slag. In some cases, two or more of these ferroalloy slags may be mixed and used.

The spheroidized ferroalloy slag is obtained by receiving the molten ferroalloy slag from the electric furnace in a ladle and crushing it while tilting the ladle, which is spheroidized to a diameter of 5 mm or less. Although those with a diameter of 2.5 mm or less are almost spherical, those with a diameter of 2.5 to 5.0 mm are formed as slightly distorted spherical (subspherical) ones.
Any of them can be used as spheroidized ferroalloy slag. Further, the blending ratio of the spheroidized ferroalloy slag is about 7: 3 to 4: 6 in the sand: ferroalloy slag (volume ratio).

[0013]

The present invention is constituted as described above, and by using the spheroidized ferroalloy slag, the strength can be increased even if the water-cement ratio of concrete is reduced, and the fluidity is good, so that a vibrator is used. Even if it is not used intentionally, the ready-mixed concrete can be sufficiently filled into the form, and therefore the initial strength can be increased.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. The molten ferrochrome slag having the composition shown in Table 1 discharged from the electric furnace was received in a ladle, and the ladle was tilted and air-crushed to produce spherical ferrochrome slag mainly having a diameter of 5 mm or less. Table 2 shows the physical property values of slag, and Table 3 shows the particle size distribution of slag.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

Table 4 shows the composition of the composition in which the ferrochrome slag was not mixed in the concrete, and the composition in which it was mixed, and Table 5 shows the test results of the concrete in Table 4.

[Table 4]

[0019]

[Table 5]

As is clear from the results shown in Table 5, those mixed with sand: ferrochrome slag (volume ratio) = 7: 3 (sample
2) requires a slight vibrator for filling, but sand: ferrochrome slag = 5: 5 (Sample 3) does not require a vibrator at the time of filling and has a high initial strength. ..

On the other hand, in the case where the ferrochrome slag was not mixed (Sample 1), the vibrator had to be used as usual, and the initial strength was less than half that of Sample 3.

[0022]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the ferroalloy slag, which has little utility value and is mostly landfilled as industrial waste, is spheroidized and used as an aggregate for concrete, thereby making it possible to use unused resources. In addition, it is not necessary to use a vibrator at the time of placing concrete, the efficiency of the placing work can be improved, and the initial strength of the concrete can be increased.

Claims (2)

[Claims] 1. A ferroalloy slag pulverized into a spherical shape having a diameter of 5 mm or less is used as an aggregate for concrete, and the volume ratio of sand: ferroalloy slag is then 7: 3 to 4: 6. Use of ferroalois lag characterized by being used as. 2. The method of using ferroalloy slag according to claim 1, wherein the ferroalloy slag is used in combination with a water reducing agent and a thickening agent.