JP2001047365A - Particle for shot blast - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the hardness to prevent the powdering of the slag by reacting a molten material of the reduced slag discharged from an electric steel furnace with an antipowdering agent, cooling a reactant, and crushing the produced hardened matter. SOLUTION: An antipowdering agent prepared by blending oxide of aluminum including metallic aluminum, iron oxide, an oxygen-contained boron compound and silicon oxide-contained mineral, is reacted with a reduced slag molten matter, whereby γ-2CaO.SiO2 and free lime existing in the reduced slag and considered as the main factor of the powdering, are reacted with silicon oxide, aluminum oxide or iron oxide in the antipowdering agent to be reformed as stable β-2CaO.SiO2, 3CaO.Al2O3, 3aO.Fe2O3, or the like, which prevents the powdering of the slag. As the oxygen-contained boron compound coexists in the antipowdering agent, the reforming reaction is further accelerated, and a part of the oxygen-contained boron compound is changed to a composite oxide such as calcium boron-silicate or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle for shot blasting.

[0002]

2. Description of the Related Art Conventionally, natural silica sand has been used as granules for shot blasting. However, natural silica sand has a problem that the hardness is insufficient due to the mixture of soft rocks, and the quality is not constant because it is a natural product, and furthermore, a large amount of silicate dust that adversely affects the human body is generated. It has been proposed to use slag discharged from a blast furnace as shot blast granules instead of the above natural silica sand (JP-A-54-54139). The slag has a higher hardness than natural silica sand and the quality is almost constant.

[0003]

However, the slag also has insufficient hardness due to insufficient hardness, so that the grinding efficiency, that is, the working efficiency, is not sufficient. Further, the slag is liable to be powdered at the time of shot blasting. In addition, the powdered material must be disposed of, and if it is generated in a large amount, the processing cost increases, and if the amount of the powdered material increases, the recycling amount decreases accordingly.

[0004] Accordingly, an object of the present invention is to provide a shot blasting granule having a high hardness and being hard to powder.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for producing a reduced slag melt discharged from an electric steelmaking furnace, an oxide of aluminum containing metallic aluminum, an iron oxide, and the like. A shot blast obtained by reacting with a powdering inhibitor comprising a mixture of an oxygen boron compound and a silicon oxide-containing mineral, cooling the reaction product, and crushing the resulting cured product. It is intended to provide granules for use, and it is desirable to rapidly cool the reaction product obtained by reacting the melt of the reduced slag with the powdering inhibitor.

[0006]

In the present invention, a powdering inhibitor comprising an aluminum oxide containing metal aluminum, an iron oxide, an oxygen-containing boron compound, and a silicon oxide-containing mineral is reacted with the reduced slag melt. Is present in the reduced slag and is the main cause of pulverization.
SiO ₂ and free lime are silicon oxides in the powdering inhibitor,
Reacts with aluminum oxide or iron oxide to form stable β-2CaO.SiO ₂ , 3CaO.Al ₂ O ₃ , 3C
The slag is reformed into aO.Fe ₂ O ₃ or the like, and powdering of the slag is prevented.

Further, such a reforming reaction of the reduced slag occurs along with a thermite reaction represented by the following formula between the metallic aluminum compounded in the powdering inhibitor and the iron oxide. The reaction is accelerated by the high heat of reaction, so that the reaction is performed quickly and uniformly. 2Al + Fe ₂ O ₃ → 2Fe + Al ₂ O ₃ + Qkcal The coexistence of an oxygen-containing boron compound in the powdering inhibitor further promotes such a reforming reaction, and a part of the oxygen-containing boron compound It is presumed that it probably becomes a composite oxide such as calcium borosilicate and contributes to the prevention of slag powdering.

When the thus obtained modified slag melt is rapidly cooled and hardened, a hardened modified slag having extremely high hardness and high strength is obtained. The shot blast granules made of the modified slag hardened material have a high hardness and thus excellent grinding power, and are hard to be pulverized, so that a small amount of powdered material is generated.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The reduced slag of the present invention is a reduced slag discharged from an electric steelmaking furnace, and has a CaO content of 10 to 60% by weight,
The content of iO ₂ is 10 to 25% by weight,
Those having about 1 to 3 (SiO ₂ ) are generally used.

[0010] The reduced slag is discharged from the electric steelmaking furnace in a molten state and reacted with a powdering inhibitor. The powdering inhibitor is obtained by blending an aluminum oxide containing metal aluminum, an iron oxide, an oxygen-containing boron compound, and a silicon oxide-containing mineral. The quality and purity of each of these compounds is not particularly limited, and for example, those generated as industrial waste can be used as they are.

That is, as the aluminum oxide containing metal aluminum, for example, so-called aluminum ash generated on the surface of molten aluminum when refining metal aluminum or regenerating metal aluminum from aluminum scrap or the like is used. As this aluminum ash, Al ₂ O
₃ (alumina): 49.7 wt%, SiO _2: 6.0 wt%, MgO: 6.3 wt%, Fe ₂ O _3: 1.5 wt%, M. Al (metal aluminum): 30.0% by weight,
A composition having a composition of CaO: 0.5% by weight and others: 6.0% by weight is given as an example.

The aluminum ash has a function of generating high reaction heat by reacting metal aluminum contained in the composition of the aluminum ash with another compound of iron oxide (thermit reaction). Free lime in the slag has an effect of reacting with alumina in the aluminum ash to form a stable compound. To exhibit such an effect, the content of metallic aluminum in aluminum ash is about 30 to
Desirably, it is 35% by weight.

The iron oxide has an effect of generating high reaction heat mainly by a thermite reaction with the metal aluminum and an effect of generating a stable compound by reacting with free lime in the reduced slag. . The form of the iron oxide is Fe ₂ O ₃ , Fe ₃ O
_4. Any of FeO may be used. As such an iron oxide, for example, a so-called steelmaking scale mainly containing iron oxide generated in a process of continuous casting, rolling of ingots, billets, and the like during the production of steel products, forging, etc. Can be. As the steelmaking scale, FeO: 37 to
40 wt%, Fe ₂ O _3: 8~17 wt%, Fe
₃ O ₄ : 46 to 52% by weight, Fe: 0.13 to 0.45
A composition having a composition of weight% is given as an example.

As the oxygen-containing boron compound, boric acid,
A boric acid compound such as borax can be used. Also,
As the silicon oxide-containing mineral, in addition to silica sand, foundry sand, river sand and the like can be used. As the molding sand, SiO ₂ : 73.20% by weight, Al ₂
O ₃ : 6.99% by weight, CaO: 1.59% by weight, Mg
O: 0.42 wt%, Fe ₂ O _3: 14.54 and a weight percent of the composition is given as an example.

An aluminum alloy containing the above metal aluminum
Oxides, iron oxides, oxygenated boron compounds and silicon
The mixing ratio of oxide-containing minerals is, for example, aluminum ash
(Al _TwoO_ThreeAs): 7-12% by weight, aluminum ash
(As M. Al): 4-7% by weight, scale (Fe_Two
O_ThreeAs): 35 to 45% by weight, oxygen-containing boron compound
(B_TwoO_ThreeAs): 3-7% by weight, sand (SiO_Twoage
T): Desirably in the range of 20 to 30% by weight.
No.

The addition ratio of the powdering inhibitor having the above mixing ratio to the reduced slag melt depends on the basicity (CaO / SiO ₂ ) of the reduced slag melt, the content of free lime, and the like. It is preferably about 6 to 8% from the viewpoint of smoothly proceeding the reaction with the substance.

In reacting the above-mentioned powdering inhibitor with the reduced slag melt, for example, the powdering inhibitor is laid beforehand in the form of loose or appropriate packaging on the bottom of a heat-resistant container, and the reduced slag is placed on this. Although a method such as injecting a melt may be used, a method in which a granular or powdery modifier is blown through a lance tube together with a carrier gas such as air or nitrogen into a heat-resistant container containing a reduced slag melt is preferable. give. That is, by contacting the reduced slag melt by blowing the powdering inhibitor with the carrier gas,
These react violently, generate exothermic foam, and cause convection agitation, so that a uniform reactant (modified slag melt) is generated very efficiently in a short time. The modified slag melt thus obtained is extremely stable after hardening and can withstand powdering.

The melt of the modified slag obtained as described above is hardened by cooling. However, in this cooling process, rapid cooling is desirable. Is preferably brought into contact with water, for example, by applying water from above. By rapidly cooling the modified slag melt in this way,
A modified slag cured product having extremely high hardness and high strength can be obtained.

Here, if the thickness of the modified slag melt in the heat-resistant container is too small, natural cooling (gradual cooling) is performed before water is applied.
This may make it easier to solidify, making it impossible to obtain the desired hardness. If the thickness is too large, the water rapidly turns into steam when water is applied, and there is a risk of steam explosion. Desirable modified slag melt thickness is 80mm ~ 1
20 mm.

When water is applied, it is desirable to prevent water from accumulating on the surface of the modified slag melt in the heat-resistant container, and if too much water is applied, water will be applied to the surface of the modified slag melt. The rapid cooling effect due to the latent heat of evaporation of water cannot be expected. The amount of water to be applied is desirably about 200 to 400 liters per second per ton of the modified slag melt. The modified slag melt is rapidly hardened by the rapid cooling. At this time, the original modified slag mass having a diameter about the thickness of the modified slag melt in the container is obtained by self-crushing.

The modified slag mass is crushed by a crusher, further crushed by a crusher, coarsely classified by a coarse sieving machine or the like, and further finely classified by a fine sieving machine or the like to obtain a granular product for shot blasting. It is said. Since these granules have an angular shape, if round and round granules are desired, they are further polished by a grinding machine to perform chamfering. After polishing, the product is finely classified again by a fine sieving machine or the like to obtain a granular product for shot blasting.

In this case, the diameter of the obtained granules is usually 0.0
It is in the range of 7 to 3 mm, preferably in the range of 0.1 to 2.5 mm, but various types should be provided in this range depending on the type of the object to be shot blasted, the desired surface roughness, and the like. Desirably, for example, both angular and round angular particles have a diameter of 2.5 to 1.25 mm (No. 1), 1.25 to 0.6 mm (No. 2), and a diameter of 0.6. ~ 0.
3mm (No.3), 0.3-0.15mm diameter (No.4), 0.15-0.07mm diameter (No.5)
Prepare five kinds of counts.

The above-mentioned crushing and crushing may be carried out while the modified slag raw mass is wet with water, or the modified slag raw mass may be dried and subjected to steps after crushing, Alternatively, the modified slag mass may be coarsely crushed and then dried to perform the processes after crushing. In the classification step, it is desirable that the residue not passing through the sieve is returned to the crushing step.

The shot blast granules of the present invention obtained in this manner have high hardness and are hardly powdered, so they are excellent in grindability, that is, workability, and prevent deterioration of the working environment due to powdered materials. In addition, there is an advantage that recyclability is high.

[0025]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these Examples.

[Example 1] Reduced sulfur discharged from an electric furnace
Load 8 tons of lag melt into slag pot, cover, and run
650 kg of powdering inhibitor through air pipe 3-5 kg air pressure
/ Cm^TwoAnd sent to the slag pot. The composition of the reduced slag is
CaO: 48.44% by weight, SiO_Two: 23.08 weight
%, FeO: 0.79% by weight, Fe_TwoO_Three: 0.08 layers
Amount%, Al _TwoO_Three: 15.24% by weight, free lime: 1.
25% by weight, S: 0.527% by weight, MgO: 7.03
Wt%, MnO: 0.34 wt%, P_TwoO_Five: 0.00
7% by weight. Further, as the powdering inhibitor, Al
Miash (M. Al: 35% content): 14% by weight, scale
(Fe oxide: 99% contained): 38% by weight, borax (B _Two
O_Three): 12% by weight, sand (SiO_Two: 60%): 3
A composition having a composition of 6% by weight was used.

The temperature of the reduced slag melt in the slag pot is 12
The temperature was 00 to 1350 ° C, and the reduced slag melt quickly reacted with the blown powder inhibitor to reach 1520 ° C and melted and boiled. After the completion of the reaction, the obtained modified slag melt was made to have a thickness of about 100 mm, and immediately the modified slag melt 1
The modified slag melt was rapidly cooled and cured by spraying 300 liters per ton of water.

The modified slag having a diameter of about 100 mm
An original mass was obtained. The Mohs hardness of the modified slag mass is 7
And the composition of the modified slag mass is CaO: 4
4.18% by weight, SiO_Two: 25.05% by weight, Fe
O: 2.83% by weight, Fe_TwoO_Three: 0.598% by weight,
Al_TwoO_Three: 17.06% by weight, free lime: 0% by weight,
S: 0.368% by weight, MgO: 4.56% by weight, Mn
O: 0.325% by weight, P _TwoO_Five: 0.004% by weight,
Na_TwoO: 0.108% by weight, B_TwoO_Three： 0.345 weight
% Of γ-2CaO.
SiO_TwoAnd free lime had disappeared.

The raw slag mass was crushed by a crusher, dried and crushed by a crusher. The crushed modified slag mass is then coarsely classified by a coarse sieve and finely classified by a fine sieve to obtain a particle size of 2.5 to 1.25 mm (No. 1) and a diameter of 1.25 to 1.25.
0.6 mm (No. 2), diameter 0.6-0.3 mm (No. 3),
Diameter 0.3-0.15mm (No.4), Diameter 0.15-0.0
It was classified into five types of granules of 78 mm (No. 5).

Using the shot blasting granules (No. 2) thus obtained, the steel surface was shot blasted. The shot blast conditions are as follows. Blasting equipment Air blasting system Blasting pressure 6kg / cm ² Blasting distance 15cm Blasting time 20sec Steel area 70 × 180mm

The parameters of the resulting rough surface (J
IS B 0601-1994) was as follows. λ _C (average wavelength of irregularities) 2.5 mm L (development length) 2.5 mm _Ra (arithmetic average roughness) 7.12 μm R _Z (ten-point average roughness) 38.2 μm _Ry (irregularities) Maximum height) 55.6 μm

Example 2 8 tons of reduced slag melt similar to that in Example 1 was charged into a slag pot, covered, and then 650 kg of a powdering inhibitor was supplied with air pressure of 3 to 5 kg / cm through a lance tube.
^It was sent to the slag pot in ² . As the powdering inhibitor, aluminum ash (M. Al: 35% content): 14% by weight, scale (Fe oxide: 99% content): 40% by weight, borax (B ₂
O ₃ : 56%): 8% by weight, sand (SiO ₂ : 60%)
Content): A composition having a composition of 38% by weight was used.

After the completion of the reaction, a rapid cooling treatment was performed in the same manner as in Example 1 to obtain a modified slag mass having a diameter of about 100 mm.
The Mohs hardness of the modified raw slag mass is 7, and the composition of the modified raw slag mass is CaO: 46.05% by weight, S
iO ₂ : 26.24% by weight, FeO: 3.01% by weight,
Fe ₂ O _3: 0.625 wt%, Al ₂ O _3: 18.0
3 wt%, of free lime: 0 wt%, S: 0.256 wt%, MgO: 3.03 wt%, MnO: 0.414 wt%, P ₂ O _5: 0.006 wt%, B ₂ O ₃ : 0.35
Γ-2Ca, which is 1% by weight and is the main cause of slag pulverization.
O.SiO ₂ and free lime had disappeared.

The raw slag mass was crushed and classified in the same manner as in Example 1. Then, shot blasting was performed in the same manner as in Example 1 using the obtained shot blasting granules (No. 2). The parameters of the resulting rough surface (JIS B 0601-1994) were as follows. λ _C (average wavelength of irregularities) 2.5 mm L (development length) 2.5 mm _Ra (arithmetic average roughness) 7.05 μm R _Z (ten-point average roughness) 36.8 μm _Ry (irregularities) Maximum height) 51.8 μm

[Comparative Example 1] Aluminum ash (containing 35% M. Al) as a powdering inhibitor: 14% by weight, scale (F
e oxide: 99% contained): 41% by weight, sand (SiO ₂ :
(Contained 60%): A modified slag mass and granules for shot blasting were prepared in the same manner as in Example 1 except that a composition having a composition of 45% by weight was used and rapid cooling with water was not performed. The Mohs hardness of the modified slag mass is 5, and the composition of the modified slag mass is CaO: 46.
05% by weight, SiO ₂ : 26.03% by weight, FeO:
2.46 wt%, Fe ₂ O _3: 0.33 wt%, Al ₂
O ₃ : 17.21% by weight, free lime: 0.18% by weight,
S: 0.37% by weight, MgO: 4.48% by weight, Mn
O: 0.28 wt%, P ₂ O _5: a 0.006 wt%, of free lime which is the main cause of the slag powdering remained.

As a result of performing shot blasting using the obtained granules for shot blasting, the parameters of the rough surface (JIS B 0601-1994) were as follows. λ _C (average wavelength of irregularities) 2.5 mm L (development length) 2.5 mm _Ra (arithmetic average roughness) 4.23 μm R _Z (ten-point average roughness) 20.8 μm _Ry (irregularities) Maximum height) 30.3 μm

Comparative Example 2 A modified slag mass and shot blast granules were produced in the same manner as in Comparative Example 1 except that rapid cooling with water was performed. The Mohs hardness of the modified raw slag mass was 6. As a result of performing shot blasting using the obtained granules for shot blasting, the parameters of the rough surface (JIS B 0601-1994) were as follows. λ _C (average wavelength of irregularities) 2.5 mm L (development length) 2.5 mm _Ra (arithmetic average roughness) 5.23 μm R _Z (ten-point average roughness) 28.8 μm _Ry (irregularities) Maximum height) 45.3 μm

From the above results, it can be seen that the roughness of the rough surfaces obtained in Comparative Examples 1 and 2 is smaller than the roughness obtained in Examples 1 and 2. This is considered to be because the hardness of the shot blast particles in Comparative Examples 1 and 2 is low and the particles are easily crushed.

[0039]

According to the present invention, it is possible to obtain shot blasting particles which have a high hardness and are hardly powdered.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Keiichi Tsuruyama, Inventor Keiichi Tsuruyama, Jyushiyama, Kaifu-gun, Aichi Pref.

Claims (2)

[Claims] Claims: 1. A pulverization comprising mixing a melt of reduced slag discharged from an electric steelmaking furnace with an aluminum oxide containing metal aluminum, an iron oxide, an oxygen-containing boron compound and a silicon oxide-containing mineral. After reacting with an inhibitor, the reaction product is cooled, and the resulting cured product is crushed to obtain a shot blast granule. 2. The shot blast granules according to claim 1, wherein the reaction product obtained by reacting the melt of the reduced slag with the powdering inhibitor is rapidly cooled.