JPH06240377A - Method for concentrating and recovering zinc - Google Patents

Abstract

PURPOSE:To separate and recover Zn as metallic Zn by heating and melting the waste contg. Zn along with a reducing agent to vaporize Zn and then cooling the gas contg. the Zn vapor. CONSTITUTION:The industrial waste contg. zinc as zinc oxide, etc., or its burnt ash is supplied into a melting furnace along with a reducing agent such as coke, heated at high temp. and melted. The contained zinc oxide is reduced to metallic zinc by the coke, or the low-b.p. zinc is vaporized. The gas contg. the zinc vapor is discharged outside the furnace and cooled, hence the zinc vapor is solidified and separated, and the zinc contained in the waste or burned ash is recovered in high yield.

Description

Detailed Description of the Invention

[0001]

The present invention relates to various kinds of waste, incineration ash from a waste incinerator, boiler ash, dust ash, etc., dust ash generated from a waste melting furnace and a metallurgical melting furnace, and a bottom. The present invention relates to a method for recovering zinc as a valuable resource from solid matter such as ash.

[0002]

2. Description of the Related Art One example of solid matter containing zinc is dust ash in a waste incinerator. Hereinafter, the dust ash of the waste incinerator will be described as an example. For the dust ash of the waste incinerator,
Since it contains heavy metals such as lead and mercury in addition to zinc, various treatment technologies have been studied from the viewpoint of environmental pollution prevention, and are described, for example, in "Environmental Technology" Vol.21 (1992) p.243-252. As described above, a method of encapsulating and stabilizing these heavy metals in a molten slag by melting and reusing the slag as a civil engineering material has been proposed.

[0003]

As described above, the conventional melt processing method does not reach the point of recovering zinc as a valuable resource. It is an object of the present invention to provide a method for concentrating and recovering a zinc content in melt processing a solid material containing zinc.

[0004]

Means for Solving the Problems The present invention provides a method for melting a solid material containing zinc in a melting furnace, and supplying a reducing agent directly or by mixing with the solid material to the melting furnace.
A method for concentrating and recovering zinc, characterized in that the zinc content in the solid matter is reduced and volatilized into gas as zinc vapor, and the gas containing this zinc vapor is cooled outside the melting furnace to solidify and collect the zinc content. Is.

[0005]

[Operations and Examples] Hereinafter, the dust ash of the waste incinerator will be described based on the test results of the melting process performed in the electric furnace. Table 1 shows the dust ash from the waste incinerator in the atmosphere.
When melted at 00 ° C., Table 2 shows that the same dust collecting ash was used as a reducing agent in the furnace and coke powder was 0.1 per 1 of dust collecting ash.
The results of analysis of the components of the dust ash, the melt, and the volatile component when melt-treated at 1300 ° C. were supplied at a weight ratio of 1: 1.
All numerical values are shown by weight ratio with the total amount of collected ash as 100.

In the melting treatment in the air atmosphere shown in Table 1, most of the zinc content contained in the dust ash was transferred to the melt, so that the zinc was remarkably concentrated in the volatile matter. Not not. This is because most of the zinc content in the collected ash exists in the form of oxides, and since the boiling point of zinc oxide is higher than the melting treatment temperature, it does not volatilize in the melting process and moves to the melt side. Conceivable.

On the other hand, in the melting process in which coke powder was supplied as the reducing agent into the furnace shown in Table 2, about 98% of the zinc content contained in the dust ash was transferred to the volatile content, resulting in a light concentration. Has been. As a result of supplying the reducing agent into the furnace, the zinc oxide contained in the dust ash was reduced to metallic zinc in the melting process, and since the boiling point of metallic zinc was lower than the melting treatment temperature, it moved to the volatile content side. It is a thing.

From the results of this test, when the solid material containing zinc is melt-processed, the reducing agent is supplied to reduce the zinc content in the solid material, and the zinc content is volatilized and concentrated in the gas as zinc vapor to be cooled and solidified and recovered. I understand that it is possible. Further, by circulating the recovered solidified substance to the object side and repeating the melting process, it becomes possible to concentrate and recover zinc at a higher concentration.

[0009]

[Table 1]

[0010]

[Table 2]

Further, the recovered solidified product is NaCl, KC.
Since a water-soluble component such as 1 is contained, it can be more effectively concentrated and recovered by washing it with water to remove the water-soluble component and then circulating it to the side of the object to be processed and repeating the melting process.

FIG. 1 shows a flow chart of an embodiment in which the present invention is applied to dust ash of a waste incinerator. Waste ash from waste incinerator a
Is washed with a part (b) of the gas ash of the melting furnace in the water washing treatment device l and supplied to the melting furnace 2 as the washing ash e. Here, the zinc content in the ash is reduced by the action of the reducing agent f supplied to the melting furnace to become zinc vapor, and the exhaust gas h ₁
Move to.

The molten slag g generated in the melting furnace is discharged to the outside of the furnace, the exhaust gas h ₁ containing zinc vapor is burned in the gas combustion furnace 3, and further cooled in the gas cooling tower 4. The cooled exhaust gas h ₃ is supplied to the dust collector 5, and the solid content in the exhaust gas is collected as gas ash. Here, the zinc content in the exhaust gas is solidified by cooling and transferred to gas ash. The gas ash of the melting furnace in which the zinc content is concentrated circulates part b of the gas ash on the supply side of the melting furnace and recovers part k out of the system.

[0014]

Industrial Applicability According to the present invention, it is possible to recover zinc as a valuable resource from a solid material which has not been recovered in the past.

[Brief description of drawings]

FIG. 1 is a flow chart of an example in which the present invention is applied to dust ash of a waste incinerator.

[Explanation of symbols]

a: Dust ash of waste incinerator, b: Gas ash (circulation) of melting furnace, c: Water for washing ash, d: Washing wastewater, e:
Washed ash, f: reducing agent, g: molten slag, h ₁ ,
_{h 2, h 3, h 4} : exhaust gas, i: Air gas combustion,
j: gas cooling water, k: melting furnace gas ash (recovered portion),
1: Washing treatment device, 2: Melting furnace, 3: Gas combustion furnace,
4: Gas cooling tower, 5: Dust collector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunji Tsukazuka 46-59 Nakahara, Tobata-ku, Kitakyushu City, Fukuoka Prefecture Nippon Steel Corporation Machinery & Plant Division

Claims (1)

[Claims] 1. A method for melting and treating a zinc-containing solid in a melting furnace, which comprises supplying a reducing agent directly or mixed with the solid to the melting furnace to reduce the zinc content in the solid to reduce zinc. A method for concentrating and recovering zinc, which comprises volatilizing the gas as a vapor into the gas, cooling the gas containing the zinc vapor outside the melting furnace, solidifying the zinc content, and collecting the zinc content.