KR100288904B1 - Method for recovering valuable metals from electric arc furnace dust - Google Patents

Abstract

PURPOSE: A method for recovering valuable metals from electric arc furnace dust is provided in which valuable metals are simply and promptly recovered from steelmaking dust by recovering the valuable metals in the steelmaking dust generated in the process of melting and recycling steel scrap in an electric furnace in a wet electrolytic process. CONSTITUTION: The method for recovering valuable metals from electric arc furnace dust comprises the processes of melting and precipitating valuable metals by injecting into a sodium hydroxide solution steelmaking dust generated when melting and recycling steel scrap with an electric furnace; separating solid contents from the valuable metals precipitated in the valuable metal melting and precipitating process using a magnetic field; depositing harmful metals in a solution separated in the solid content separation process in a cement form; and recovering zinc by electrolyzing the solution that is separated and deposited from the harmful metal deposition process.

Description

Steelmaking dust valuable metal recovery method of electric furnace

The present invention relates to a method for recovering valuable metals of steelmaking dust in an electric furnace, in particular, recovering valuable metals such as high purity zinc and lead iron oxides from a steelmaking dust generated during the melting and regeneration of scrap metal into an electric furnace in a steelmaking plant in a simple process. The present invention relates to a method for recovering valuable steel metallurgical dust.

Steelmaking dust is generated in the interior of the electric furnace by high heat and impurities contained in the scrap iron in the process of putting the scrap metal collected in a conventional steel mill into an electric furnace and regenerating the iron, wherein the constituent component of the steelmaking dust is iron oxide (FeO). ), Zinc oxide (ZnO), silicon oxide (SiO ₂ ) and various other metallic inorganic materials. Especially harmful to lead (Pb), chromium (Cr), cadmium (Cd), copper (Cu), etc. Because it contains metal, it is classified as designated waste in environmental regulations.

Therefore, when the dust generated during the steelmaking process is released into the atmosphere, serious air pollution is caused.

Meanwhile, although zinc (Zn) of the valuable metals contained in the steelmaking dust has been imported (56,000 tons 47 million dollars in 1997) every year, when zinc is recovered from the steelmaking dust by recycling, Although 40,000 tons of US $ 30 million was replaced, the cost of waste disposal and environmental pollution were prevented.

And to date, as a method of recovering valuable metals in steelmaking dust generated during steelmaking in a steel mill, heat metallurgy methods, wet metallurgy methods, electrolytic methods, and scrap surface treatment methods have been proposed. This complicated and excessive treatment cost is generated, which is not only economical, but also has many problems such as generating secondary pollutants.

It is an object of the present invention to recover valuable metals from steelmaking dust generated during the melting and regeneration of scrap metal in an electric furnace by wet electrolysis using caustic soda with less secondary pollution. It is intended to be able to recover quickly.

In order to realize the above object, the present invention is a process for dissolving valuable metals by adding steelmaking dust generated during melting and regeneration of scrap iron by an electric furnace to a caustic soda solution, and using the magnetic field of the valuable metals dissolved in the process. It is characterized in that it comprises a step of separating from the solid, a step of depositing the harmful metal in the form of cement in the solution separated in the process, and a step of recovering zinc by electrolytically separating and precipitated solution in the process.

1 is a process chart for the method for recovering steelmaking dust valuable metals of the present invention

2 is a schematic diagram of a method for recovering steelmaking dust valuable metals of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying examples.

1 is a process chart for the valuable metal recovery method of the electric furnace of the present invention, Figure 2 is a schematic diagram of the valuable metal recovery method of the electric furnace of the present invention.

Example

1) Dissolution and Precipitation Process

10-400 g / l caustic soda (NaOH) solution was added at a rate of 10-300 g / l steelmaking dust generated in an electric furnace and dissolved at about 90-110 ° C. for 2 hours. Zinc (Zn), lead (Pb), Copper (Cu) and cadmium (Cd) are dissolved.

_{^{ZnO + 2 OH - → ZnO 2}} - + H 2 O

_{^{PbO + 2 OH - → HPbO 2}} -

_{^{CuO + 2 OH - → CuO 2}} - + H 2 O

CdO + OH ^- → HCdO ₂ ^-

When the dissolved harmful metal is transferred to the settling tank and settled for about 10 minutes, the floating iron Fe (Fe ₂ O _3, ZnFe ₂ O ₄ ) and Ca (OH) ₂ remain in the solid phase and remain in the solid phase. Solid suspended solids are separated and filtered through a filter press, filtration washing.

2) Magnetic field separation process

The solid suspended solids dissolved and separated in the dissolution and precipitation process are separated and stored as a magnetic field using a magnet.

3) Filtration and precipitation process

In the dissolution and precipitation process, the supernatant in which noxious metal is dissolved in the precipitation tank is transferred to a lead (Pb) recovery tank by a pump, and 0.97 g of zinc powder is added to maintain lead temperature to precipitate lead. When the powder is added, the reaction takes place so that zinc is further dissolved and lead (Pb), copper (Cu) and cadmium (Cd) are precipitated, which is obtained in the form of metal cement. This metal cement is removed from the filter press.

The zinc powder added to the solution is a part of the zinc powder produced in the process as follows.

^{_{Zn + HPbO 2 - → Pb +}} ZnO 2 - + H 2 O

^{_{Zn + CuO 2 - → Cu +}} ZnO 2 -

^{_{Zn + HCdO 2 - → Cd +}} ZnO 2 - + H 2 O

At this time, the amount of zinc powder added is about twice the chemical amount to be precipitated.

Meanwhile, after depositing lead in the recovery tank, the solution is moved to a filtration tank using a pump, and the precipitated lead and suspended solids are completely filtered using a 1 μm filter paper, and then the solution is sent to the electrolytic cell.

The solids of the settling tank and the suspended solids after filtration are made into a cake state of an appropriate size after filtration and washing and then re-introduced into an steelmaking process with electricity or used as a raw material of cement, and the wastewater is circulated back into the dissolution tank.

In addition, the precipitated lead is washed and dried to recover high purity lead powder, and the washed waste water is sent to the dissolution tank.

4) Electrolysis and Recovery Process

After filtering the precipitated lead and suspended solids introduced into the electrolytic cell in the filtration and precipitation process, the solution is nickel in the positive electrode (+), magnesium (Mg) cell in the negative electrode (-) in the electrolytic cell, and the current density is 375 A / ㎡ In this case, zinc is recovered by electrolysis for about 1 hour at 50 ° C, filtered and dried to recover zinc of high purity, and the electrolytic waste is circulated back to the dissolution tank.

As a result of the test using the steelmaking dust with the zinc content of 17% by the above process, the recovery rate of zinc was 9.15%, and the recovery rate of lead was 1.58%. As the recovery rate increased, the purity of recovered zinc remained 80-92%.

As described above, the present invention is to recover the valuable metal in the steelmaking dust generated during the melting and regeneration of the scrap iron in the electric furnace by the wet electrolytic method using a caustic soda with less secondary pollution, the high-purity of the valuable metal Zinc and lead can be recovered and used to prevent environmental pollution due to the release of harmful metals, as well as to replace imports, and the waste water generated after the recovery of valuable metals can be recycled to a dissolution tank to reuse it. It will provide the effect to prevent the pollution of the environment in advance.

Claims (4)

Injecting steelmaking dust generated during melting and regeneration of scrap metal into an electric furnace into a caustic soda solution to dissolve and precipitate valuable metals; Separating the solids from the valuable metal precipitated in the above process using a magnetic field; Precipitating the toxic metal in the solution separated in the process in the form of cement; And Electrolytic steelmaking dust valuable metal recovery method comprising the step of recovering zinc by electrolytically separating and precipitated solution in the process. The method of claim 1, wherein 10-300g / ℓ of steel dust generated in the electric furnace to 10-400g / ℓ caustic soda (NaOH) solution in the dissolution and precipitation process is dissolved at about 90-110 ℃ for 2 hours In other words, zinc (Zn), lead (Pb), copper (Cu), cadmium (Cd) is to be dissolved electric furnace steel dust dust valuable metal recovery method characterized in that. The method of claim 1, wherein the filtration and precipitation process is performed by adding 0.97g of zinc powder in a state of maintaining the temperature of 65 ℃ in the settling tank in the form of metal cement in the form of lead (Pb), copper (Cu), cadmium (Cd) An electric furnace steel dust dust valuable metal recovery method characterized in that to be precipitated. 2. The electrolytic and recovery process according to claim 1, wherein the electrolytic and recovery process is performed by installing nickel in the positive electrode, magnesium in the negative electrode, and zinc cells in the electrolytic cell, with a current density of 240 to 375 A / m 2 and 40 to 80 ° C. An electric steelmaking dust valuable metal recovery method characterized by maintaining the temperature to recover the zinc by electrolysis for about 1 to 2 hours.