JPS59153848A - Recovery method of metal in steel manufacture dust utilizing molten slag - Google Patents

Abstract

PURPOSE:To recover metals in the dust using a simple installation and at a low operation cost by separating the metals in the dust by blowing the dust together with an exothermic agent into molten slag. CONSTITUTION:High-temp. slag 2 produced in the steel manufacturing stage is filled in a slag ladle 1; a blowing pipe 3 is inserted thereto and a hood 4 is provided above the slag ladle 1. A duct 5 connected to a suction apparatus is fitted to the hood 4 and a dust collector 6 is provided to the midway of the duct. A powder mixture prped. by mixing an exothermic agent with the dust collected from the exhaust gas produced in the steel manufacturing stage is blown into the slag 2 in the ladle 1 together with compressed air through the blowing pipe 3. Said powder mixture is dispersed into the slag 2 to mix therewith and heated to high temp. by the sensible heat and the heat of reaction of the exothermic agent to melt the metal in the dust. Low-b.p. metals such as Zn, Pb, etc. are volatilized and floated up and collected by the hood 4 from the surface of the slag 2, then sucked in the duct 5. Solidified powder metals obtd. by cooling are recorvered by the dust collector 6.

Description

Detailed Description of the Invention The present invention mainly involves melting metals with relatively low boiling points, such as zinc and button, among the metals contained in the steelmaking gas 1~ collected from the exhaust gas generated during the steelmaking process. This invention relates to a method of separating and recovering slag using sensible heat.

Steelmaking dust contains large amounts of metals such as zinc and lead, as well as their oxides, so if it is disposed of in a landfill, it will be treated as hazardous industrial waste, and it can be freely disposed of in a landfill subject to legal regulations. I am no longer able to do that.

Conventionally, metals have been extracted from steelmaking dust by heating and melting the steelmaking dust in a tunnel furnace or electric furnace to evaporate and separate the metals, or by mixing chemical solutions to extract and separate the metals. The treatment method used was to separate and collect the waste, and then landfill the rendered harmless residue.
Separation and recovery of metals as described above has the drawback of requiring large equipment and high operating costs.

The object of the present invention is to separate and recover metals in steelmaking dust with extremely simple equipment and low operating costs.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

A slag ladle 1 is filled with high-temperature molten slag 2 generated during the steelmaking process, a blowing pipe 3 is inserted into the slag ladle 1, and a hood 4 is placed above the slag ladle l.
A duct 5 connected to a suction device (not shown) is connected to the hood 4, and a dust collector 6 is interposed in the middle of the duct 5.

Then, when a powder mixture of steelmaking dust and exothermic agent is blown into the molten slag 2 in the slag ladle 1 through the blowing pipe 3 together with compressed air, the mixture diffuses into the molten slag 2 and melts. The metal in the steelmaking dust is heated to a high temperature by the sensible heat of the slag 2 and the reaction heat of the exothermic agent, and the metal in the steelmaking dust is melted.
Low-boiling point metals such as zinc and button vaporize and float to the surface, evaporate from the surface of the molten slag 2, are collected in a hood 4 and sucked into a duct 5, and the powdered metals that are cooled and solidified are collected by a dust collector 6. be done.

Next, an example of the implementation results of the method of the present invention will be explained.Table 1
700 kg of steelmaking dust containing the metals shown in Table 1 are mixed with 125 kg of aluminum ash having the components shown in Table 1 as a reducing agent to produce 7000 kg of molten slag having the components shown in Table 4.
When the steelmaking dust was blown into the steelmaking dust with compressed air, 123 pieces of dust containing the metals shown in Table 3 were collected, and the recovery rate of low boiling point metals from the steelmaking dust was 55% for zinc and 99% for lead.

In addition, the components of the slag after treatment were analyzed.

As shown in Table 5, there is almost no change from Table 4 showing the components before treatment, and Table 6 shows the results of a hazardous substance elution test conducted on the slag after treatment according to the method notified by the Environment Agency.
All of them were below safety standards.

In addition, column a of Tables 2 to 6 above indicates slag discharged during the oxidation stage, column b
The column shows the slag discharged during the reduction period.

As clarified by the above explanation, the method for recovering metals from steelmaking dust using molten slag of the present invention involves mixing a heat generating agent with steelmaking dust collected from exhaust gas generated during the steelmaking process. The gist is to evaporate the metal contained in the steelmaking dust by blowing the mixture together with a compressed gas into the high-temperature molten slag produced in the process, and to solidify and collect the evaporated material, Since the exothermic agent is mixed with the steelmaking dust and blown into the molten slag together with the compressed gas, the molten slag is stirred by the gas, and the steelmaking dust and exothermic agent are evenly mixed into the molten slag, which improves the visibility of the molten slab. The metal is actively melted and evaporated by heating due to the heat of reaction between the heat and the exothermic agent, making it possible to obtain a high recovery rate, making it possible to effectively utilize the recovered metal, and making the residue harmless. Because it is mixed into slabs, it can be used as roadbed material, etc., and can be disposed of in landfills.
It can be carried out with a simple device using conventional equipment at a steel manufacturing site, such as a blow pipe and a duct equipped with a hood and a dust collector, and only the exothermic agent is consumed, so it can be operated at an extremely low cost. It produces the effect that can be achieved.

Table 1 Analysis values of aluminum ash (weight%) Table 2 Analysis values of steelmaking dust before treatment (weight%) Table 3 Analysis values of recovered material during treatment (weight%) Table 4 Analysis values of slab before treatment (weight%) Table 5 Analytical values of slag after treatment (weight%
) Table 6 Elution test results of treated slabs according to the notification of the Environment Agency The attached drawing is a schematic illustration of an example of an apparatus for carrying out the method of the present invention.

1. Varnish slag pot 2: Molten slag 3: Blow pipe 4: Hood 5: Duct 6: Dust collector Applicant: Chubu Kohan Co., Ltd.

Claims (1)

[Claims] A heating agent is mixed with steelmaking dust collected from exhaust gas generated during the steelmaking process, and the mixture is blown together with compressed gas into the high-temperature molten slag generated during the steelmaking process to evaporate the metals contained in the steelmaking dust. A method for recovering metals in steelmaking dust using molten slag, characterized by solidifying and collecting the evaporated material.