JP2002088410A - Method for effectively using fly ash and iron-containing waste material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively using fly ash and iron-containing waste material by which the fly ash and the iron-containing waste material, produced in large quantities in iron works can effectively be used as resources. SOLUTION: After mixing the fly ash with the iron-containing waste material such as iron oxide scale, scarfing waste of iron and steel cast slab, this mixture is granulated to make a briquette, and this briquette is charged onto molten iron or molten steel, and the yield of the iron is improved by adjusting the basicity of the molten slag, and also, reducing iron oxides in the iron-containing waste material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for effectively utilizing fly ash and iron-containing waste.

[0002]

2. Description of the Related Art In a steelworks, fly ash is generated from a coal-fired power plant installed on the premises. This fly ash is a fine powder having a size of about 1 to 10 μm, which is inconvenient and complicated to handle. It has to be disposed of with a lot of labor and cost. Also, in steel mills, iron oxide scale is generated from continuous cast slabs or steel slabs heated to high temperatures during rolling, or fusing chips are generated when continuous cast slabs are blown to a predetermined length, Scarfing debris is generated when removing the surface flaw of the billet, or blast furnace, converter,
Iron is evaporated in a sintering furnace or the like to generate dust. These iron oxide scales, fusing debris, scarf debris, dust, etc., are low in quality despite containing iron such as iron oxide, so they are disposed of at high cost as waste containing iron that has no use value. It was.

[0003]

The object of the present invention is to solve the above-mentioned conventional problems and to combine fly ash, which has been conventionally difficult to dispose, with iron-containing waste, which has also been difficult to dispose of. Another object of the present invention is to provide a method for effectively utilizing fly ash and iron-containing waste, which is effectively utilized as a resource.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method of mixing fly ash with iron-containing waste such as oxide scale of iron and fusing debris of steel slab and granulating. The briquette is fed onto hot metal or molten steel to adjust the basicity of the molten slag and to reduce iron oxide in iron-containing waste to improve iron yield. The basic composition is to make effective use of ash and iron-containing waste. In the present invention, a method of converting hot metal or molten steel into which briquettes are charged into hot metal in a converter or molten steel in an electric furnace after hot metal pretreatment is defined as the invention of claim 2, and in these inventions, iron-containing waste A method of mixing briquettes by mixing a binder such as water glass and lignin together with fly ash and then granulating the briquettes. The specific gravity of the briquettes in these inventions is set to 2 to 6, and the briquettes are mixed with molten slag and hot metal. 5. A method for effectively forming a molten slag by staying at an interface with slag.
Invention.

The method of effectively utilizing fly ash and iron-containing waste according to the present invention is to mix fly ash with iron-containing waste to enhance formability, granulate the briquettes, and subject the briquettes to hot metal pretreatment. The molten iron in the converter or the molten steel in the electric furnace is poured onto the molten iron or molten steel, thereby melting the SiO ₂ component in the fly ash into the molten slag and adjusting the basicity of the molten slag. In addition to reducing the amount of silica and aluminum ash conventionally used to adjust basicity, it promotes the reduction reaction of iron oxide in iron-containing waste by burning C in fly ash to oxidize. It recovers iron from iron and improves the yield of iron.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, fly ash generated from a coal-fired power plant is mixed with iron-containing waste such as iron oxide scale, fusing debris, scarfing debris, and dust generated on the premises of a steel mill, and the mixture is mixed with water. To give the fly ash caking properties and granulate the mixture to produce briquettes. When granulating briquettes, iron-containing waste is mixed with fly ash, water glass, lignin, corn starch, small piece waste plastics, etc. as a binder to further improve the briquette cohesion and form the briquettes. Can be made hard to break. Binders such as water glass, lignin, corn starch and the like can be gelatinized as they are, and small piece waste plastics can be heated and softened by steam to form iron-containing waste into briquettes.

FIG. 1 shows a process of granulating briquettes by a briquetting machine.
A mixture 2 containing waste plastic heated and softened by heating to 150 to 200 ° C. is placed 50 mm wide and 50 m long on the outer peripheral surface.
m, by rotating and rotating the orbiting wheels 3 and 3 having a forming concave portion (not shown) having a depth of about 15 mm, discharge the liquid between the rotating wheels 3 and 50 to obtain a width of 50 mm, a length of 50 mm and a thickness of 30 mm.
A briquette 4 in the shape of a charcoal having a size of about mm can be granulated. The specific gravity of the briquette 4 is preferably 2 to 6, particularly preferably 2.2 to 5.5. The reason is that the specific gravity of hot metal is generally 7.4 to 7.8 and the specific gravity of slag is about 1.5, so that the specific gravity of briquette 4 is 2 to 2.
6, the briquette 4 is lighter than the hot metal,
This is because the briquette 4 can be retained at the interface between the molten slag and the hot metal as a material heavier than the slag, and the briquette 4 can be easily melted and slag.

[0008] By the way, as an integrated manufacturing process of steel making,
Iron pretreatment furnace → molten steel transfer pan → converter → continuous casting process
There is a process of manufacturing steel. In such an integrated manufacturing process
First, in the hot metal pretreatment furnace, the temperature of the hot metal,
At about 1350 ° C., the basicity of the molten slag (CaO / SiO
_Two) Is about 2.1 and desulfurization, desiliconization, and dephosphorization
However, sulfur and phosphorus in the hot metal are removed by this hot metal pretreatment.
Although it can be reduced to the specified content,
Carbon content from initial 4.3% (mass%, same hereafter) to 3%
0.3-0.5% content
The silicon that has been removed is almost desiliconized, and the silicon concentration in the hot metal is almost
Since it becomes zero, _TwoDo not add
It is impossible to adjust the basicity of molten slag
No.

The hot metal that has been pretreated is transported to a converter by a hot metal transfer ladle and decarburized by oxygen blowing in the converter to reduce the carbon content in the hot metal to a desired amount.
Adjusted. After that, it is necessary to further adjust the basicity of the molten slag for fine adjustment of components such as desulfurization and dephosphorization, iron yield, and Mn yield. However, silicon is almost contained in the hot metal as described above. Therefore, it is necessary to add SiO ₂ from the outside together with CaO for adjusting the basicity of the molten slag. Conventionally, silica is put into molten iron at about 1650 ° C in a converter together with slag formation accelerators such as fluorite and aluminum ash.
The basicity of the molten slag was adjusted to 3.5 to 4.

The basicity of the conventional molten slag as described above
In contrast to the adjustment method, in the present invention,
Briquette mixed with fly ash and granulated in converter
By pouring it together with CaO onto the molten iron
Adjust the basicity of the lag to 3.5-4. Fly ash
Is SiO_Two60-80%, Al_TwoO_Three30-15%,
Because it contains 20 to 5% of C,
To SiO_TwoAnd Al_TwoO_ThreeEffective use as a source of
Reduce the use of silica and aluminum ash
To produce harmful fluorine such as fluorite
There is no need to use any ore. Also fly fly
The menu is SiO as described above._TwoAnd Al_TwoO _ThreeIs a mixture of
SiO_Two, Al_TwoO_ThreeLower melting point than simple substance
The properties are good. C in fly ash is a heat source
To promote the reduction reaction of iron oxide,
To effectively use all the ingredients that make up fly ash
Can be used.

In addition, even in an electric furnace, when the molten steel does not contain Si, the basicity of the molten slag can be adjusted economically by introducing the briquette of the present invention. The molten steel whose composition has been adjusted as described above is conveyed to a continuous casting step, and is continuously cast into a slab or a bloom such as a bloom by a continuous casting machine.

The iron oxide in the briquettes charged on the hot metal of the converter and the molten steel of the electric furnace is reduced to iron, so that the yield of iron can be improved. The reduction of iron oxide proceeds, for example, according to the following equation.

Embedded image Since the above reaction formula is an endothermic reaction, the reaction can be promoted by supplying heat energy from the outside. Therefore, by burning C in the fly ash, it is possible to supply reaction heat to the above reaction, thereby promoting the reduction reaction of iron oxide, and improving the yield of iron. The generated CO gas is recovered as unburned LDG (converter gas) and burned in an annealing furnace, so that the steel sheet can be effectively heated with energy saving.

The method for effectively utilizing fly ash and iron-containing waste according to the present invention is to mix fly ash with iron-containing waste such as oxide scale of iron and swarf of iron and steel slabs, and then granulate to form briquettes. This briquette is put on the hot metal in the converter or the molten steel in the electric furnace after the hot metal pretreatment, and the SiO ₂ component in the fly ash is melted in the molten slag to adjust the basicity of the molten slag. ,
The combustion of C in fly ash promotes the reduction reaction of iron oxide in iron-containing waste to recover iron from iron oxide, so that the yield of iron can be improved.

[0014]

[Table 1] [Formulation example] The binders used in the formulation examples in the preceding table were No. 3 and No.
5, No.10 is water glass, No.4, No.7 is lignin, No.6, N
o.8 and No.9 constarch. The specific gravity of the iron-containing waste varies from 3.0 to 7.8 depending on the type.

[0015]

As is apparent from the above description, the present invention provides a briquette by mixing iron-containing waste and fly ash, which are generated in large quantities in an ironworks, into briquettes. Injected into molten steel, the SiO ₂ component in the fly ash is melted in the molten slag, and the basicity of the molten slag is adjusted to reduce the amount of silica and aluminum ash conventionally used. Since the reduction reaction of the iron oxide in the iron-containing waste is promoted by the combustion of the carbon therein to recover the iron from the iron oxide, the yield of iron can be improved. In addition, since the briquette is manufactured by mixing the binder with fly ash to the iron-containing waste and granulating the briquette, the briquetting force of the briquette is increased, so that the briquette is hardly deformed during transportation. . Furthermore, the specific gravity of the briquette is 2
There are various advantages such as 6 that briquettes can be easily formed into molten slag by staying at the interface between the molten slag and the hot metal. Therefore, the present invention is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a diagram showing a granulation process by a briquetting machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hopper 2 Mixture 3 Swirl wheel 4 Briquette

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C22B 1/243 C22B 1/244 1/244 1/248 1/248 7/00 F // C22B 7/00 7/02 A7 / 02 B09B 3/00 ZAB F term (reference) 4D004 AA16 AA37 AA43 BA05 CA14 CA15 CC03 CC13 CC15 DA03 DA11 4K001 AA10 BA14 BA15 BA22 CA26 CA29 DA05 FA10 GA06 GA16 4K002 AB01 AB06 AB07 AE02 4K014 CB03 CB09 CE

Claims (4)

[Claims] Claims 1. A fly ash is mixed with iron-containing waste such as iron oxide scale and fusing debris of steel slab and granulated to form briquettes. The briquettes are poured onto hot metal or molten steel to form molten slag. A method for effectively utilizing fly ash and iron-containing waste, characterized in that the basicity of the iron is adjusted and the iron oxide in the iron-containing waste is reduced to improve the yield of iron. 2. The method for effectively utilizing fly ash and iron-containing waste according to claim 1, wherein the briquettes are put into the hot metal in the converter or the molten steel in the electric furnace after the hot metal pretreatment. . 3. The fly ash and the iron-containing waste according to claim 1, wherein the iron-containing waste is mixed with fly ash together with a binder such as water glass and lignin and granulated to form briquettes. How to make effective use of 4. The briquette according to claim 1, wherein the specific gravity of the briquette is 2 to 6, and the briquette is retained at an interface between the molten slag and the hot metal to form a molten slag.
Effective use of fly ash and iron-containing waste described in the item.