JPH11106840A - Recovery of valuable metal components from metallurgical dust - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the heating efficiency and reduce the heating efficiency by adding a carbonaceous substance as a reducing agent to dust generated from a metallurgical process to recover valuable metal components such as zinc and iron contained therein. Provide a method that can be collected in time. The object of the present invention is to provide a method of recovering volatile valuable metal components by supplying dusts and carbonaceous substances generated in a metallurgical process to a heating furnace, wherein the heating source of the furnace is a surface heating type burner. The problem is solved by a method for recovering valuable metal components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for recovering volatile valuable metal components such as zinc components and other valuable metal components such as iron components from dusts 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-claim burner placed in the area, reducing and evaporating and recovering oxides of zinc, lead and cadmium, and recovering 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.

[0005]

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, the reduction reaction of the metal oxide takes a relatively long time, and a very large space is required in the vertical direction of the upper part of the rotary hearth furnace, and the rotary hearth furnace itself becomes huge. There was a problem.

[0006]

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

That is, the present invention relates to a method for recovering volatile valuable metal components by supplying dusts and carbonaceous substances generated in a metallurgical process to a heating furnace, wherein the heating source of the furnace is a surface heating type burner. The present invention relates to a method for recovering valuable metal components.

The surface heating type burner used in the present invention comprises:
It is characterized in that the dust pellets spread on the hearth can be heated uniformly. As shown in FIG. 3, the conventional long-frame burner 1 is attached to a side wall of a furnace wall 4 covered with a heat insulating material, and is mounted on a hearth 6 of a refractory 7 running by wheels 8. Dust pellets spread 5
Is heated by the radiant energy 9 of the burner flame 2 which blows out horizontally from each burner 1 supplied with the premixed gas 3 of fuel and air. In this heating furnace, as shown in FIG. 4, dust pellets immediately below the frame are exposed to a high temperature, while dust pellets located between the frames have a low temperature, and the temperature unevenness is remarkable. . For this reason, if the temperature of the dust pellet immediately below the frame is set to a temperature at which fusion of the dust pellets does not occur (about 1150 ° C.), the temperature of the dust pellet located between the frames becomes low, and carbonaceous The reduction reaction of valuable metal components such as zinc oxide and iron oxide by the substance becomes difficult to proceed.

On the other hand, the surface heating type burner 10 of the present invention comprises:
As shown in FIG. 1, an example is attached to the ceiling of the furnace wall 4. In this surface heating type burner, as shown in FIG. 2, dust pellets are uniformly heated at all positions in the furnace, and are most suitable for a reduction reaction of valuable metal components such as zinc oxide and iron oxide by a carbonaceous substance. Temperature can be set
The reduction reaction is completed by heating for a shorter time. For this reason, the apparatus for the same dust processing amount becomes smaller, and the fuel required for heating the dust pellets can be saved.

As shown in FIG. 3, the conventional long-frame burner 1 requires a large furnace space.
Heat is dissipated not only in the direction of the hearth where the dust pellets 5 are located but also in the direction of the upper ceiling of the furnace, so that heat loss is large. On the other hand, in the surface heating type burner 10 of the present invention, as shown in FIG. 1, the back layer of the burner plate (the surface corresponding to the upstream side of the fuel gas) is at room temperature to about 100 ° C., and the surface layer of the burner plate ( Since heat is concentrated only on the fire surface on the downstream side of the fuel gas and most of the heat is given to the dust pellet, the heat loss is extremely small, and the fuel consumption can be reduced accordingly.

[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 oxides, sulfides, and the like in dust (including sludge). Regarding the content of these metal components, in the case of dust generated in the iron making process, iron is 1 to
It is about 80% by weight and zinc is about 0.01 to 50% by weight. Also, the particle size of the dusts is about 0.1 μm to 1 mm,
Usually, it is 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,
Depending on the amount of zinc oxide and other metal oxides, the weight ratio of oxygen to oxygen in the form of metal oxides is between 0.
About 1 to 20, preferably about 0.2 to 10 is appropriate.

For example, in the case of blast furnace wet dust, dust 1
The range of 0.01 to 0.2 parts by weight of the carbonaceous substance relative to parts by weight 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. Above all, 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 surface heating type burner is used as a heating source of the heating furnace.

The surface heating type burner is a burner for heating by blowing out a flame from each communicating hole of a porous body having a communicating hole, and usually has a plate shape. The porous body may be formed by binding granular materials, but in general, a burner plate formed by sintering fibers of metal, ceramics, or the like and forming it into a plate shape is used.

As the material of the burner plate, stainless steel,
Metals such as nickel alloys or ceramics such as quartz and alumina are used alone or mixed at an appropriate ratio. The fibers used are usually long fibers having a diameter of about 10 to 50 μm and a length of about 10 to 100 mm. The thickness of the porous body is usually about 2 to 6 mm, and the porosity is about 80 to 95%. Further, as the burner plate, a composite sintered plate obtained by laminating a metal fiber sintered body and a ceramic fiber sintered body can be used. In this case, it is preferable to use a metal fiber sintered body for the back layer on the upstream side of the fuel gas and a ceramic fiber sintered body for the surface layer on the downstream side.
Commercially available products can be used for these fiber sintered plates.

The surface heating burner plate is arranged to heat the dust layer from above or below depending on the structure of the heating furnace. In the case of a hearth moving type furnace, it is preferable to dispose it on the ceiling. The distance from the surface heating burner plate to the dust pellet layer is appropriately determined, but is usually 5 to 100 cm.

In this surface heating type burner, a fuel and an oxygen source, usually air, are fed to one side, and a fuel premixed with the air or the like passes through a communication hole of a porous body to the other side, and the other side receives a fuel and an oxygen source. A flame is spouted from the surface.

The fuel used for the surface heating type burner includes:
There is no particular limitation as long as it is a flammable gas. Natural gas, LP
Any of G and coke oven gas may be used. The equivalent ratio (mixing ratio between fuel and air) of the premixed gas used in the burner plate is preferably in the range of 0.5 to 1.5, and more preferably in the range of 0.8 to 1.2. The gas ejection speed from the burner plate is 2 to 30 cm / sec.
Is more preferable, more preferably 5 to 20 cm / sec.
c.

In the surface heating type burner constructed as described above, the premixed gas of the fuel gas and the air is uniformly injected from the entire surface of the burner plate. When ignited by a spark plug, the flame propagates over the entire surface of the burner plate and starts burning in a state of being attached to the surface, and the flame does not float from the surface.
Thus, the surface of the burner plate is uniformly heated, and heat from the high-temperature gas and heat due to high radiation are generated. This heat is transferred to the dust pellets spread on the hearth, and the dust pellets are uniformly heated. By heating, the volatile valuable metal components, such as zinc oxide, contained in the dust pellets react with the carbonaceous material, reduce and volatilize, and are discharged out of the system in a form accompanying the exhaust gas. 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 substance, 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 surface heating type burner is set such that the surface temperature of the dust pellet is in the range of 1000 to 1150 ° C.
If the surface temperature of the dust pellets exceeds 1150 ° 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.

[0027]

【Example】

Example 1 The dust sample used in the experiment was obtained by mixing 10 parts by weight of coke breeze with 100 parts by weight of blast furnace wet dust having the chemical composition shown in Table 1.
1 part by weight of bentonite and 10 parts by weight of galvanized sludge shown in Table 2 were mixed and granulated into spherical pellets of 6 to 9 mm.

[0028]

[Table 1]

[0029]

[Table 2]

The pellets were placed in a circular hearth rotary furnace (diameter 8).
00 mm). The dust pellet on the hearth was adjusted with a threlan so as to be almost two layers. The surface heating burner plate placed on the ceiling of this furnace is made of long fibers (fiber diameter 2) made of stainless steel (SUS316) as a fiber material.
(5 μm, fiber length 50 mm) and a fiber mat burner sintered on a 4 mm-thick donut board. LPG was used as fuel gas, and was supplied from a gas cylinder to a nozzle provided in the burner main body, and air was premixed with a fuel gas ejected from the nozzle on the upstream side of the burner main body by a blower. After igniting the gas, 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.

Examples 2 to 10 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 An experiment was conducted in the same manner as in Example 1, except that a long frame burner was used instead of the fiber mat burner. Table 3 shows the experimental conditions and experimental results.

[0033]

[Table 3]

[0034]

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 surface heating type burner arranged on the ceiling of the furnace, so that uniform heating of the dust pellets and shortening of the heating time are achieved, and heat loss is significantly reduced. This has a remarkable effect such that the fuel source unit can be kept low and the equipment can be downsized.

[Brief description of the drawings]

FIG. 1 shows an arrangement of a surface-heating type burner according to the invention;
It is one vertical sectional view of a hearth moving type furnace.

FIG. 2 is a temperature distribution of a dust pellet when the dust pellet is heated by the surface heating type burner according to the present invention.

[FIG. 3] A conventional long frame burner is arranged.
It is one vertical sectional view of a hearth moving type furnace.

FIG. 4 shows a temperature distribution of a dust pellet when the dust pellet is heated by a conventional long frame burner.

[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 Surface heating type burner

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masahiro Matsuura 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (4)

[Claims] 1. A method for recovering volatile valuable metal components by supplying dusts and carbonaceous substances generated in a metallurgical process to a heating furnace, wherein the heating source of the furnace is a surface heating type burner. For recovering valuable metal components 2. The method according to claim 1, wherein the dust is one or a mixture of two or more kinds selected from blast furnace dust, converter dust, and sludge. 3. The method for recovering valuable metal components according to claim 1, wherein the heating furnace is an annular hearth rotary furnace. 4. The method for recovering valuable metal components according to claim 1, wherein the surface heating burner is a sintered plate of metal fibers.