JP2002060851A - Method for recovering valuable metallic component from metallurgical dust and the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating efficiency-improved method for recovering, in a short time valuable metallic components such as zinc, iron, etc., contained in dusts by adding a carbonaceous material as the reducing agent of dusts developed in a metallurgical process. SOLUTION: In the method for recovering volatility valuable metallic components by supplying the dusts developed in the metallurgical process and the carbonaceous material into a heating furnace, a short flame burner is characteristically used as the heating source in the furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and recovering volatile valuable metal components such as zinc components and non-volatile valuable metal components such as iron and nickel components from dust generated in a metallurgical process such as iron making.

[0002]

2. Description of the Related Art Heretofore, several methods have been known for recovering valuable metal components such as zinc components and iron components from dusts generated in an iron making process.

[0003] For example, Japanese Patent Application Laid-Open No. 5-125454 discloses that dust discharged from a steelmaking factory is mixed with a carbonaceous substance and an organic binder to form a pellet, which is then sent to a rotary kiln, and the side of the kiln is fed. Direct reduction, characterized by heating the pellets with a long flame burner placed in the area, reducing and volatilizing the oxides of zinc, lead and cadmium, and collecting the remaining dust pellets as reduced iron pellets. A process and apparatus are disclosed.

Further, Japanese Patent Publication No. 64-5233 discloses that
To a target containing iron oxide, nickel oxide, cobalt oxide, etc., a reducing agent such as coke powder is added to form a pellet, which is charged into a rotary hearth rotary furnace along the rotary path of the ring hearth. A moving hearth furnace and a heat treatment method for obtaining reduced metal pellets by heating pellets with a plurality of long frame burners are disclosed.

Further, Japanese Patent Application Laid-Open No. 11-106840 discloses that dust and carbonaceous substances generated in an iron making process are supplied to a rotary hearth rotary furnace to form volatile valuable metal components and non-volatile valuable metals. In the method of separating and recovering components,
A method and an apparatus for recovering valuable metal components using a surface heating burner as a heating source are disclosed.

[0006]

However, in the direct reduction process described in JP-A-5-125454 and the heat treatment method described in JP-B-64-5233, the heat loss is very large, The basic unit is large, and furthermore, a very large space is required in the vertical direction of the upper part of the rotary hearth furnace, so that the rotary hearth furnace itself becomes huge.

On the other hand, in the method described in Japanese Patent Application Laid-Open No. 11-106840, since the sintered plate of the metal fiber, which is the heating element of the surface heating burner, is severely deteriorated at a high temperature and has a short life, a high running cost and a low There was a problem that resulted in an operation rate.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, a short flame burner is used as a heating source when heating metallurgical dusts such as steelmaking and recovering valuable metal components. It has been found that the problem can be solved by using.

That is, in a method of supplying dusts and carbonaceous substances generated in a metallurgical process to a heating furnace to separate and recover volatile valuable metal components and nonvolatile valuable metal components, the heating source of the furnace is short. The present invention relates to a method for recovering valuable metal components, which is a flame burner.

[0010] The short flame burner used in the present invention is attached to the ceiling of the furnace wall, and is characterized by an extremely short flame length of 50 cm or less. Therefore, the dust pellets spread on the hearth can be uniformly and efficiently heated without being directly exposed to the flame. Conventional long frame type burners are attached to the side wall of the furnace wall, and the ceiling height needs to be high so that the dust pellets and the ceiling spread on the hearth are not directly exposed to the flame. There was a problem that heat dissipation to ceilings and opposing walls other than dust pellets was large. Further, in a surface heating burner using a metal fiber sintered plate, there is no problem of heat dissipation, but 1100 ° C.
If the sintering plate is continuously used at the above-mentioned high temperature, the fixing portion of the sintered plate is damaged, and there is a problem that replacement is required in about 50 to 100 hours. On the other hand, in the short flame burner used in the present invention,
By controlling the flow of the fuel gas and air, a short flame is formed, so that the heat loss can be reduced and the burner life at the time of high temperature use can be sufficiently extended.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Dusts generated in a metallurgical process include blast furnace dust, converter dust, and surface treatment waste liquid sludge (galvanizing system, chemical conversion system) generated in an iron making process, and electric furnace. System dust, cupola system dust, etc. are typical, but metallurgy of other metals,
For example, blast furnace dust and converter dust generated in copper smelting, lead smelting, tin smelting, and the like can be applied.

[0012] These dusts contain various valuable metal components, that is, valuable metal components. This metal component is divided into a volatile metal component and a non-volatile metal component. The volatile metal component is a metal component that becomes a gas at a heating temperature in a heating furnace in a metal state generated by reduction, and is, for example, zinc, cadmium, lead, or the like. Examples of non-volatile metal components include iron, nickel, cobalt, chromium, titanium, manganese and the like. These metal components mainly exist in the form of oxides, sulfides and the like in dust (including sludge). In the case of dusts generated in the iron making process, the content of these metal components is 1 iron.
About 80% by weight and about 0.01 to 50% by weight of zinc. The particle size of the dusts is about 0.1 μm to 1 mm, usually about 0.1 to 200 μm.

The carbonaceous substance is a substance that reduces valuable metal components by heating in a heating furnace to metallize. Examples of the carbonaceous substance used include coke flour, pulverized coal, and charcoal. The carbonaceous material preferably has a particle size of about 0.1 to 1000 μm, particularly about 0.1 to 500 μm.
The amount of carbonaceous material used is the amount of iron oxide contained in dust,
Depends on the amount of zinc oxide and other metal oxides.
In addition, carbon originally contained in dusts also reduces metal oxides. For this reason, the amount of carbonaceous material used is the weight ratio of the sum of the carbon contained in the dust and the carbon in the carbonaceous material used to oxygen in the form of a metal oxide that can be reduced at the treatment temperature. About 0.1-20, preferably 0.2
About 5 is appropriate.

For example, in the case of blast furnace wet dust, dust 1
Oxygen in the metal oxide is about 0.16 parts by weight, and carbon in the dust is 0.23 parts by weight based on parts by weight.
In this case, the weight ratio of carbon contained in the dust to oxygen in the form of metal oxide is preferably about 1.4, so that it is not necessary to add a carbonaceous substance. On the other hand, in the case of plating sludge, oxygen in the metal oxide is about 0.11 part by weight with respect to 1 part by weight of dust, and carbon is not contained in dust. In this case, the range of 0.02 to 0.5 parts by weight of the carbonaceous substance per 1 part by weight of dust is appropriate. The carbonaceous material is heated in a heating furnace while being uniformly mixed with dusts.

It is preferable that the dusts are granulated after adding a carbonaceous substance and a granulation accelerator and then charged into a heating furnace.

The granulation accelerator itself forms a strong bond between the dust particles by curing itself (prevention of re-pulverization of the granulated material by heating). Properties required for the granulation accelerator include: curing with mixing with water, curing at room temperature,
The curing strength does not decrease even when exposed to a high temperature. Bentonite, lime, cement and the like can be used as such a granulation accelerator. The amount used is dust 1
The range of 0.005 to 0.2 parts by weight of the granulation accelerator relative to parts by weight is appropriate.

Dust to which a predetermined amount of a carbonaceous substance and a granulation accelerator have been added is kneaded by adding water, and formed into pellets having a predetermined particle size using a disk pelletizer, a pressure molding machine or the like. The shape of the pellet may be any of a sphere, a cylinder, an almond, and the like. Further, the particle size of the pellet is preferably in the range of 2 to 20 mm, more preferably 5 to 20 mm.
範 囲 15 mm.

The type of heating furnace for heating dusts together with the carbonaceous substance is not limited, but a moving hearth furnace is preferred.

As the hearth moving type furnace, an endless moving grate type and an annular hearth rotating type are used. Among them, an annular hearth rotary furnace is preferable because the amount of dust (secondarily generated dust) generated in the heat treatment process of dust pellets is small and the recovery rate of zinc is high. The charging of the dusts and the carbonaceous substance into the heating furnace may be of a batch type, an intermittent type, or a continuous type, but it is preferable that the dusts and the carbonaceous substance are continuously charged into the hearth moving type furnace. The dust pellets charged into the furnace are spread on the hearth in a layer having a thickness of about 10 to 40 mm.

The present invention is characterized in that a short flame burner is used as a heating source of a heating furnace. The short flame burner generates a strong swirling flow by injecting and mixing air that has passed through a swirler together with fuel, and spreads the flame in the radial direction along an arc-shaped (flapper-shaped) burner tile to spread it in a radial direction. It is a burner that generates a flame. The burner flame surface is made of high heat-resistant alumina tiles of 50 to 80%, and has heat resistance up to a furnace temperature of 1350 ° C.

The short flame burner is arranged to heat the dust layer from above or below depending on the structure of the heating furnace. In the case of a movable hearth furnace, it is preferable to dispose it on the ceiling. The distance from the short flame burner to the dust pellet layer is determined as appropriate, but is usually 30 to 200 cm.

The fuel used for the short flame burner is not particularly limited as long as it is a flammable gas. Natural gas, LPG,
Any gas such as coke oven gas can be used. The mixing ratio of fuel and air used in the burner is 0.5 to
The range of 1.5 is preferable, and 0.8-1.
2 range.

In the short flame burner constructed as described above, the mixed gas of the fuel gas and the air spreads in the radial direction along the arc-shaped (flapper-shaped) burner tile due to the strong swirling flow, and the cup-shaped short flame is burned. This produces a flame. Flame thickness is 5
The distance to the dust pellet can be set as short as 30 to 200 cm because it is extremely thin, that is, up to 50 cm. Thus, uniform and highly efficient heating can be achieved by reducing the heat radiation surface not used for heating the dust pellets.

By heating, the dust pellets are discharged out of the system in a form in which volatile valuable metal components such as zinc oxide and the like react with the carbonaceous material, reduce and volatilize, and accompany the exhaust gas. You. Most of the volatile valuable metal vapor such as metallic zinc discharged outside the furnace is reoxidized as the temperature decreases, and is recovered almost in the form of a metallic oxide such as zinc oxide. At the same time, non-volatile valuable metal components such as iron oxide in the dust pellets are reduced by the carbonaceous material, and are discharged from the furnace outlet as metal pellets such as reduced iron and collected. The heating temperature of the dust pellet by the short flame burner is such that the surface temperature of the dust pellet is 1000 to 1300.
It is set to be in the range of ° C. If the surface temperature of the dust pellets exceeds 1300 ° C., fusion of the dust pellets occurs, which is not preferable. The heating time is set so that valuable metal components can be sufficiently recovered within a practical range.

[0025]

Example 1 The dust sample used in the experiment was prepared by mixing 1 part by weight of bentonite with 100 parts by weight of blast furnace wet dust having the chemical composition shown in Table 1 and granulating it into spherical pellets of 6 to 9 mm. It was done.

An annular hearth rotary furnace (diameter 800 m) with the pellets as a heat source and a short flame burner installed on the ceiling
m) was charged continuously. Dust pellets on the hearth
The screen was adjusted so as to have almost two layers.

LPG was used as fuel gas, and processing was performed at a predetermined temperature for a predetermined time. During this time, dust (secondary generated dust) generated from the furnace was collected, components were analyzed, and the composition of the pellets after the processing was analyzed. Table 3 shows the experimental results.

Example 2 A dust sample used in the experiment was prepared by mixing 100 parts by weight of galvanized sludge having the chemical composition shown in Table 2, 20 parts by weight of coke breeze and 1 part by weight of bentonite to form a spherical particle of 6 to 9 mm. This was granulated into pellets. Other experimental conditions were the same as in Example 1. Table 3 shows the experimental results.

Examples 3 to 8 In the method of Example 1, an experiment was conducted by changing the mixing ratio of the sample, the processing temperature and the processing time. Table 3 shows the experimental conditions and experimental results.

Comparative Example 1 In the method of Example 1, instead of the short flame burner,
The experiment was performed using a long frame burner. Table 3 shows the experimental conditions and experimental results.

Comparative Example 2 In the method of Example 1, instead of the short flame burner,
The experiment was performed using a fiber mat burner. Table 3 shows the experimental conditions and experimental results. Example 1
And Comparative Example 2 were subjected to a 168-hour durability test.

In Example 1, continuous processing was possible for 1000 hours without any problem, and there was no problem in appearance of the burner after use. On the other hand, the fiber mat burner of Comparative Example 2
Under the condition of 150 ° C., the combustion state became unstable in 43 hours with a fast burner, and replacement was necessary. When the degraded fiber mat burner was disassembled and observed, it was estimated that the surrounding area where the sintered metal fiber was fixed was severely deformed due to high temperature, gas leaked, a flame was generated from the surrounding area, and combustion became unstable. .

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

As described above, according to the present invention, a carbonaceous substance and a granulation accelerator are added to dusts generated in an iron making process to form pellets, which are continuously fed to a hearth moving heating furnace. So that it is heated by a short flame burner placed on the ceiling of the furnace, so that heat loss is greatly reduced and burner life is prolonged.
The present invention has a remarkable effect such as a low maintenance cost and a reduction in the size of the equipment.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a moving hearth furnace in which a short flame burner according to the present invention is arranged.

FIG. 2 shows a conventional long-frame burner.
It is a longitudinal section of a hearth moving type furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Burner 2 Burner flame 3 Fuel-air premixed gas 4 Furnace wall 5 Dust pellet 6 Hearth 7 Refractory 8 Wheel 9 Radiation energy 10 Short flame burner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22B 19/30 C22B 19/30 19/38 19/38 (72) Inventor Tatsuro Ariyama Marunouchi, Chiyoda-ku, Tokyo 1-2-1, Nihon Kokan Co., Ltd. (72) Inventor Tsutomu Shikata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Ichiro Ueno 1-chome, Marunouchi, Chiyoda-ku, Tokyo 1-2 Nippon Kokan Co., Ltd. (72) Inventor Yutaka Suzukawa 1-2-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Nippon Kokan Co., Ltd. 3K061 NA04 NA13 4K001 AA10 AA19 AA30 BA14 CA16 GA07 GB12

Claims (1)

[Claims] In a method for supplying dust and carbonaceous material generated in a metallurgical process to a heating furnace to separate and recover volatile valuable metal components and non-volatile valuable metal components, the heating source of the furnace is short. Method for recovering valuable metal components characterized by being a flame burner