JPH0565548A - Manufacture of sintered ore together with removal of zinc in dust - Google Patents

Abstract

(57) [Summary] [Objective] To provide a method for recovering an iron source of iron-containing dust and sludge containing zinc generated in an iron mill, especially a method for producing a sinter. [Composition] Iron-containing dust containing zinc, sludge and a reducing agent such as powder coke are mixed and granulated. When the pellet is charged into a sintering machine, a normal sintering compounding material is charged. The pellets are intensively arranged and sintered in a lower layer portion that is at least ⅓ or less of the thickness of the bed raw material layer. [Effect] Reduced and volatilized zinc can be removed without reprecipitating in the sintered layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering an iron source of zinc-containing iron-containing dust and sludge generated in an iron mill, and more particularly to a method for producing sinter.

[0002]

2. Description of the Related Art Various dusts and sludges containing iron are generated from ironworks. Various methods have heretofore been proposed as this processing method. For example, JP-A-52
The reduced pellet method, the cold pellet method, and the like disclosed in No. 61108 are known. But,
Because of the high cost of the reduced pellet system and the poor evaluation of the reduced pellet, attempts have been made recently to discard it.
Further, in the cold pellet method, when the zinc-rich dust is used as a raw material, zinc concentration is likely to occur in the blast furnace, and the zinc-containing dust tends to be gradually reduced. There is only a reduced pellet method for preventing the concentration in the blast furnace and using zinc-containing dust as a raw material. However, as described above, the reduced pellet method has the drawbacks of high construction cost and high operating cost.

Further, Japanese Patent Laid-Open No. 51-69413 discloses a method in which iron-containing dust is mixed with calcium chloride as a binder and pellets are separately charged into an ordinary sintering machine and sintered. However, in this method, all of the sintering raw material layers are pellets of iron-containing dust. The zinc removal rate cannot be expected so much because the zinc is precipitated by being cooled in the wet zone formed in the above. In order to solve this, a pretreatment of sufficiently drying the pellets of iron-containing dust is required, and the treatment cost is high.

[0004]

Therefore, an inexpensive method for producing dezincification raw materials such as iron-containing dust and sludge is expected. The present invention responds to this by providing a method that is cheaper than a reduced pellet method and requires almost no equipment investment, and is an epoch-making method in terms of recycling zinc-containing dust and sludge.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a sintering compounding raw material when a pellet containing pellets obtained by mixing and granulating zinc-containing dust, sludge and a reducing agent such as powder coke is charged into a sintering machine. A method for producing a sintered ore that also functions as dezincification of dust, characterized in that the pellets are concentratedly arranged in a lower layer portion of at least ⅓ or less of a thickness of a raw material bed for sintering bed. .. Hereinafter, the present invention will be specifically described.

In the present invention, dezincification for producing iron-containing dust, sludge, etc. containing zinc as a raw material for sintering is caused in the sintering process. That is, iron-containing dust containing zinc, kneading sludge and coke powder, granulated pellets,
Alternatively, if necessary, pellets are produced by adding a binder such as cement or quick lime to create a pellet, and a strong reducing atmosphere is created around the pellet, and zinc is volatilized in the reducing atmosphere. This is a method that is performed without affecting volatile zinc during the sintering process of the compounded raw materials.

As described above, the characteristic of the sintering process is that, unlike the rotary kiln, the temperature pattern is not uniform, that is, the temperature is high and low in the direction of the height of the sintering bed, and the zinc component volatilized voluntarily in the bed lower layer. It is characterized by precipitation. Therefore, if the method in which the powdered coke-containing pellets are simply used in the sintering process, even if a strong reducing atmosphere is generated around the pellets and zinc volatilizes there, the lower layer is cooled and zinc precipitates. , Are trapped in the raw material layer. Therefore, the removal rate of zinc is not sufficient for the product sintered ore as a whole, and zinc concentration in the blast furnace is inevitable.

According to the present invention, iron-containing dust containing zinc, composite pellets of sludge and coke coke are intensively arranged in a lower layer of a sintering bed in which a usual sintering compounding raw material is charged, and It is intended to prevent the precipitation of the reduced and volatilized zinc from occurring in the lower layer of the sintering bed. That is, in order to prevent the volatilized zinc from re-precipitating in the sintering raw material layer, the sintering raw material layer is present below the charging layer of the iron-containing dust containing zinc and the composite pellet of sludge and coke. The dezincification is ensured by limiting the place where the volatilized zinc is deposited in the lower layer part of the sintering raw material layer, not the raw material layer, but after the sintering flue.
It can prevent zinc concentration problem in blast furnace.

The above iron-containing dust containing zinc, the composite pellet of sludge and coke coke is concentrated in the lower layer portion of at least 1/3 or less of the thickness of the sintering bed material layer in which the usual sintering compounding material is charged. The removal of zinc occurs because the thicker the loading layer of the above zinc composite pellets is, the more the process of volatilization of zinc in the layer and the precipitation in the wet zone formed in the lower layer occur. Because it lowers the rate,
The thinner the loading layer of the zinc-containing composite pellet, the higher the zinc removal rate.

Further, the above-mentioned iron-containing dust containing zinc, the composite pellet of sludge and coke coke is charged into a usual sintering compounding material at least 1 to the thickness of the sintering bed material layer.
As means for intensively arranging in the lower layer part of / 3 or less,
For example, the above-mentioned composite pellets are charged before charging the usual sintering compounding raw material by a two-step charging method or concentrated charging in a bedding layer.

[0011]

[Example] Target dust and its zinc content Blast furnace secondary ash (zinc content = 3.5%) Transfer secondary ash (zinc content = 1.3%) Dust blending ratio during granulation Blast furnace Secondary ash: Rolling secondary ash = 50:50 (Zinc content 2.4% T-Fe content = 50%, Zn / Fe
= 0.0480) Pellet granulation The above dust mixture was kneaded by an Erich mixer and granulated by a pan-type pelletizer.

Sintering pot test conditions (1) Target raw material (A) A general sintering raw material is pseudo-granulated. (Powder coke content = 3.5%) (B) 5% of powder coke on the above pellets (1 to 3 mmφ)
Added so that the coke powder covers the pellet surface.

(2) Pot test condition The bed thickness in the pot test is 500 mm. Part 50
Pellets of (B) were stacked at the height shown below on the lower layer of 0 mm, and the general raw material of (A) was stacked thereon and ignited and sintered according to a conventional method.

Pellet layer thickness (a) 100 mm (b) 150 mm (c) 200
mm (d) 250mm (e) 300mm (f) 400mm (g) 500mm Zinc content of pot sinter [Experiment (1)] (1) Experimental results (g) The zinc content is shown below.

[0015]

[Table 1]

(2) Consideration In the thickness direction of the sintering bed, although zinc is removed from the upper layer to 200 mm, the lower the layer is, the higher the zinc content is. The zinc powder was present so as to cover the surface of the bedding ball. From this,
It is true that zinc is volatilized around the pellet, but it is precipitated in the sintered bed layer. Therefore, the dezincification rate as a whole was low (8.5%). Also, from the table in (1) above, the layer thickness is 2 after the zinc volatilizes.
It is suggested that zinc precipitation does not occur around 00 mm.

[Experiment (2)] The pellet layer thickness was set from the lower layer to 1
A pan test was performed on the pellets with the thickness changed from 00 to 500 mm, and the zinc content in the pellet portion was measured.

(1) Experimental Results Zn / Fe in the pellet portion are shown below.

[0019]

[Table 2]

* Fed bed ore condition x: Fine zinc powder is present in a sticky state. Δ: A white powdery substance adhered to only a part of the bedding floor ball. ◯: Zinc powder is not found at all in the bedding floor balls.

(2) Consideration As the pellet layer is brought to the lower layer, the dezincification rate increases and the zinc deposition in the bed ore becomes lighter. Therefore, the zinc deposition in the bed ore can be reduced. To prevent this, it is necessary to keep the pellet layer below 150 mm from the bottom. That is,
It can be said that dezincification occurs smoothly when the thickness is 1/3 or less of the bed layer thickness.

[0022]

INDUSTRIAL APPLICABILITY According to the present invention, pellets of zinc-containing iron-containing dust or the like are sintered in a normal sintering process to perform dezincification treatment without reducing or volatilizing zinc again without precipitating it in the sintered layer. The industrial value that can be achieved is great.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Tsutomu Tanaka 5-3 Tokai-cho, Tokai-shi Nippon Steel Corporation Nagoya Steel Works Premises Nippon Steel Nagoya Cord Pellet Factory

Claims (1)

[Claims] 1. When firing iron-containing dust containing zinc, sludge and a reducing agent such as powder coke and granulating the raw material into a sintering machine as a raw material, a sintering compounding raw material is charged. A method for producing a sintered ore that also serves as dezincification of dust, characterized in that the pellets are concentratedly arranged in a lower layer portion of at least 1/3 or less of the bed thickness of the bed material.