JPS5918137A - Pig iron, steel slag ph control - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention! ! This invention relates to a method for making iron slag and steel slag neutral or nearly neutral so that they can be effectively used as sand for sandblasting and other purposes.

Generally, when blast furnace slag is slowly cooled by discharging it into fields, it becomes melilite (2
CaO-A40. -8iO, -2C*0-MgO-2S
i02) It mainly contains Ca8 and has the drawback of eluting sulfur oxides and forming yellow water, but it has almost no disintegrability. If it is water-cooled, it becomes mainly glassy and has no collapsibility, but has latent hydraulic properties, so it is used as a raw material for cement and as an admixture for blast furnace cement.
Since it shows a high value of 10 to 11.4, its usage is limited. For example, when used as sand for sandblasting, the surface of the steel sheet becomes alkaline, causing problems such as discoloration of the paint after painting. In order to prevent this, it is necessary to wash the sand after sandblasting, and even if it is used as backfill sand, the leached water is highly alkaline, causing environmental problems.

Similar to blast furnace slag, steel slag has a high pH value and has the same problem.

That is, the converter slag contains γ and β-2CaO*SiO,, FeC
a0 (free lime) mainly Gehlenai) (2CaO・Red, 03・Sin,) Akermanite (2CaO-MgO
-2SiO, ), magnetite (Feρ4), hematite (Fetus), tustite (FeO), etc. Special converter slag may contain bericraze (MgO), and autoclave treatment (ASTM method,
2 Em at 200°C and 20kszGy for 4.3 hours
If a particle size of -10 mol.

Electric furnace slag is roughly divided into oxidation phase slag and reduction phase slag, the former being β and Na'-2CaO-8i0.11:, and the latter being γ-2C.
There are cases where it is rich in aO・SiO, and cases where it is rich in 3CaO・2SiO, and the former has a decay rate of about 10% by weight or less, while the latter expands and collapses (dusting) during the cooling process, and is mostly 100 FJtX. Disintegration and dissolution test show pH of about 110-114.

Ferrochrome slag is spinel (MgO・8s Ot)
Mainly forsterite (2Mg0aSiOt), felsinite (Fe0-A403) and enstatite (
Contains MgO, SiO, ), etc. and has no disintegrability, but Cr,
0. Contains about 6 to 7 JiX, and when eluted according to the method notified by the Environment Agency, the total amount of chromium ions is about 0.1 ppm.
Elutes at 2 ppm.

In addition, special steel slag is γ and β-2CaO-8iO,, F, C
aOCaO-2CaO-@2SiO,, 2CaO-A4
0. -8iO,, diopside (CaO-MgO@2
Contains SiO, ), etc., and contains about 6 to 7 Cr, 03
11JiX, and when eluted using the same method as above, the total amount of chromium ions is about 0. It elutes from lppm to 2.5ppm, and disintegrates at about 78% Jll:96, and when an elution test is performed, the pH
indicates approximately 110-113.

The cause of these collapses is F*CaO, MgO+ 2Ca
O-8iO, 3CaO-2SiO.

The present invention utilizes the sensible heat of various slags having the above-mentioned properties while they are in a molten state, or supplies external heat to the various molten slags, silicate rocks or minerals, red mud, karami, etc. Melting and reacting one or more types of mineral burnt sand, coal ash, and dust to perform a chemical reaction there, and then rapidly cooling it to form a glassy substance, thereby lowering its pH to a neutral or near-neutral value. The gist of this is to add the above-mentioned silicate rocks, minerals, red mud, karami, foundry sand, coal ash, dust, and other additives to ironmaking percentage steel slag by the following method. There is.

■ Inject into the steelmaking furnace from the beginning or middle of steelmaking.

■ Pour the steel into the steelmaking furnace after tapping.

■ Injected in contact with the slag flow discharged from the steelmaking furnace.

■ Inject it in contact with the falling position of the slag flow discharged from the steelmaking furnace.

■Used as a substitute for slag in a slag pot.

■ Pour the slag into the slag pan so that it forms a sandwich with the slag.

■ In contact with the position where the slag falls from the blast furnace tap into the ladle,
Or put it in contact with the slag flow.

■ ■■■■■ method, charge the lance-like material,
Bubble by blowing bubbling gas.

■ After pouring into the ladle before the end of continuous casting, drain the slag from the ladle.

In addition, since a large amount of the above-mentioned additives is added to t-rice, which is made into a neutral or weakly alkaline slag, the method described in ■■■■ is effective in effectively utilizing sensible heat.

Here, while the slag is in a molten state, Sin, , Az
, o, .

The purpose of adding unused resources and industrial waste containing Fe, Os, etc. is to effectively utilize the sensible heat of the molten steel slag, and the additives include Sin or A71. ．． 08
Although it is sufficient to use only Sin, , A40. When used alone, the disadvantage is that the melting temperature is high, making it difficult for reactions to occur.

Next, experimental results regarding the steel slag processing method of the present invention will be described below.

First, Table 1 shows the chemical analysis values (electrical values X) of the raw materials used in this experiment.

After drying Nire et al.'s sample for more than 24 hours in a constant temperature dryer at 105 to 110°C, additives such as steel slag and red mud were crushed to 3W or more with a sample grinder (however, since the dust is fine, the particle size was left unchanged). in),! ! ! ! Only the steel slag was subjected to magnetic separation, and then coarsely crushed to less than 0 grains to make a Zegel cone, and the melt temperature was measured.

Further, using the same sample, the absolute viscosity was measured at each temperature using a crucible rotation type viscosity measuring machine.

In addition, put magnetic tailings etc. of 3vA or less into an electrofused magnesia crucible, hold it for 15 minutes in a siliconite electric furnace maintained at 1550℃, and after melting, additives such as red mud and silicate rock. After about 6 minutes, the crucible was taken out and air crushed by tilting it in the place where air was coming out from the nozzle of the wind crushing device.
A sample of 5mM or less is used as sandblasting sand,
Specific gravity, elution test, Vickers hardness, etc. were measured.

Some of the test results are shown in Table 2 and below.

In addition, for all of the samples shown in Table 4 above, F-Ca
O-containing rice has a weight of 0.00% and its disintegration rate is 0.00% by weight.

The abbreviations of the minerals listed in Table 4 are as follows (hereinafter referred to as surface I:/).

sp・・・・・・MgO・M, 0゜""""Kou2Mg0-8iO.

En −=−−−−−−MgO−8iO.

Mf・・・・・・MgO・F2O.

β-C,S,, -β-2CaO@SiO.

r-C! S +++ T 2C, 0-8tO.

AK −−−=−−・−2CaO@MgO−2SiO!
G@,-,,,-20ao-Az,O,-8i0゜CS...Ca5 F-CsO...Free-CaO He......F et 05Mg...・・・
...Fe5Os WiS...Fe0 C3A...3CaOeA40゜For the raw material slag shown in Table 7 above, in addition to the above ions, Cu
, Cd, Pb, Zn, Mn, As
Although the eluted ion concentration was measured for T*Hg, these ions were not detected in all cases.

As mentioned above, when the slag that has been remelted four needles in the electrofused magnesia crucible is subjected to air crushing, it is cooled in detail in the crucible,
The pH of the eluate decreases because it is more rapidly cooled than when it is cooled in the crucible taken out of the furnace, and the degree of vitrification is greater.

Next, put 5 parts of special steel slag into a Niru-set electric furnace and melt it. Before tapping, put 5 parts or less of slate into a ladle, and then discharge it into a ladle and use a blower and compressed air flow. Table 8 shows the various properties of the granulated product when the granulated material was granulated by blowing it using a blow crusher.

As shown in Table 8, the special steel slag mixed with 1ON of slate has a pH close to neutrality and can be used satisfactorily as sand for sandblasting due to its other properties.

As described above, the steelmaking and ironmaking treatment method of the present invention is to convert the slag into neutral slag by adding one or more types of silicate rocks, minerals, karami, hook-burning sand, etc. to the slag. It can be modified and effectively used as sand for sandblasting, etc., and it is also possible to lower the viscosity and solidification temperature, and when it is crushed by air, it becomes easier to recover sensible heat.

Patent applicant: Japan Magnetic Separation Co., Ltd. There is a person in charge of Yoshiki Haru-2 ( )6

Claims (1)

[Claims] 1. Add one or more of silicate rocks or minerals, red mud, karami, foundry sand, coal ash, and dust to the molten pig iron slag or steel slag in an amount of 10 to 40 weight f based on the amount of molten slag mentioned above.
A method for adjusting the pH of ironmaking and steelmaking slag to 19, which is characterized by adding f1X to cause a melting reaction, followed by rapid cooling (and thereby modifying it to neutral or nearly neutral).