JPH04198431A - Method for removing copper in steel iron - Google Patents

Abstract

PURPOSE:To efficiently remove copper from copper-contg. high carbon molten iron by bringing a copper-contg. scrap steel into contact with Na2S series flux, executing decoppering treatment to subject the copper-contg. flux to molten salt electrolysis and to reutilize the flux. CONSTITUTION:Copper-contg. high carbon steel scrap 1c melted by using the energy of a carbonaceous material is brought into contact with Na2S series flux by stirring and mixing in a reaction vessel 2a to remove away copper components in the molten iron into the flux as copper sulfide. The CuS-contg. Na2S series flux 2f is fed to a molten salt electrolytic cell 3a, and the decopperized high carbon molten iron 2g is fed to a steel making furnace or the like. In the molten salt electrolytic cell 3, metallic copper 3e precipitated in the cathode is formed into molten copper, is piled up on the cell bottom 3f and is recovered via an exhaust port 3g. The Na2S series flux 4a is separated and recovered via an exhaust port 3h and is recycled for the following decopperizing operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention makes it possible to remove and separate the copper content in scrap, which has become a major problem in the recycling of steel scrap, which has been increasing in recent years. This paper relates to a method for removing copper from steel.

[Prior Art] When recycling scrap, which has been increasing in recent years, it is important to efficiently remove the playing card elements represented by copper and tin that accompany these scraps, as well as to facilitate the recycling of scrap. This is an extremely important technical issue in ensuring the material properties of recycled steel.

Furthermore, although there are the above-mentioned problems when recycling steel from scrap, compared to the process that uses a lot of carbonization as the primary energy key to produce steel from iron ore through reduction-oxidation refining, it is mainly used for remelting. Since it is possible to recycle steel with less energy, it would be possible to improve the use of scrap if there was a technology to efficiently remove copper and tin, which are problems when recycling steel from scrap, as a countermeasure to global warming caused by CO2. This is a new technology.

For this reason, research and development in this field is actively being carried out in order to suppress the generation of CO2 and to efficiently utilize the increasing amount of scrap.Although the following principle inventions are publicly known, they are not practical technologies. ■ After physically disassembling scrap and separating harmful components by manual or magnetic separation methods, the scrap is blended into raw materials that contain almost no harmful components and used within the range that does not cause problems in terms of the material properties of the product. is the current situation.

For example, with this method, there is a problem in that it is not possible to recycle a large amount of scraps of automobiles, plated scraps of drinking water cans, etc.

On the other hand, regarding the removal of copper from high carbon molten iron, there is a fundamental technical knowledge that uses Na2S-based flux to separate and remove Cu2S, which is a copper component in iron, in the flux. Tetsu-to-Hagane 74 (1988) 4
P, 640, and CAMP-ISIJ VOU2 (1
989) 1239.148, 12111, etc.

Regarding the removal of tin, tin-plated steel is reacted with sulfur gas at 400℃ to 500℃ for several minutes, and then peeled off as SnS during the cooling process.CAMP-ISI
J voU3 (+990) 1183, also 0 in steel
．． When a sufficiently high S content of about 1% is contained, it can be removed by evaporation preferentially over Fe during the vacuum treatment process or blown acid refining (CAMP-ISIJ voJ-3 (1999)).
0) 1184-1185), etc. have been discovered, but these are only theoretical findings and have not been established as practical techniques.

[Problems to be Solved by the Invention] φ In view of the above-mentioned current situation, the present invention provides a method for efficiently removing copper from steel.

In other words, the conventional method of physically disassembling scrap and separating and removing copper parts by manual or magnetic sorting methods is limited to scrap that can separate and remove copper-containing parts by these methods. Not only is the applicability limited, but productivity is also a problem.

Therefore, it cannot be a sufficient solution as a technology for removing copper from steel in response to the expected future generation of large amounts of scrap. On the other hand, the copper removal technology using Na2S-based flux, which was previously shown as a principle invention, removes copper components that are difficult to separate and remove using the physical separation methods mentioned above. The copper-containing high-carbon molten iron is carburized and melted at 1200-1500°C, and the copper-containing high-carbon molten iron undergoes a contact reaction with a flux containing Fe5-Na2S as the main component, and is separated and removed in the flux as Cu2S. This suggests the possibility of wider application. However, when using this method to decopper from 0.3% Cu copper-containing high carbon molten iron to 0.03% Cu for a wide range of steel applications, Na2S flux or a huge flux of approximately 450 kg per ton of molten iron is required. The price of the necessary flux is high, and in order to treat the large amount of flux generated, a process equivalent to copper refining can be considered, but it is economically problematic.

The present invention provides a means for efficiently removing copper from copper-containing high carbon molten iron using a flux containing Fed-Na2S as a main component.

[Means for Solving the Problems] The present invention involves carburizing and melting copper-containing scrap to obtain copper-containing high-carbon molten iron, and then contacting it with a molten flux containing Na2S as a main component at 1,200 to 1,500°C to form a molten iron. In this method, the copper component of Cu2S is separated and removed as copper sulfide in the Na2S-based flux, which includes the step of separating the Na2S-Cu2S-based molten flux and leading it out of the system, and the step of electrolyzing the molten flux to remove the copper component of Cu2S. Na2 with reduced copper sulfide content after separation as metallic copper in the cathode part
A method for removing copper from steel, characterized in that a flux containing S as a main component is separated and recovered and reused for copper removal treatment from copper-containing high carbon molten iron.

Also. The sulfur gas generated at the anode part during molten salt electrolysis of molten flux is preheated with Sn-plated steel material and 400-5
After the contact reaction is carried out at a temperature of 00° C., the Sn component is peeled off and removed as SnS.

By developing a technology that efficiently separates and removes copper contained in scrap, which cannot be easily separated using physical separation methods, the inventor has developed a technology that efficiently separates and removes copper contained in scrap, which cannot be easily separated using physical separation methods. Various studies have been conducted to regenerate steel that can be used in a wide variety of applications.

However, as shown above, copper-containing carbon-iron molten iron and Na
Fundamental knowledge has been obtained that makes it possible to separate and remove copper from molten iron by utilizing the copper fractional equilibrium between 2S-based fluxes. The inventor of the present invention has made various studies to efficiently apply this principle and has achieved the desired goal.

In other words, its technical configuration consists of the following six steps, for example, and this Shiraki invention separates and recovers the copper component from the Cu2S in the flux as metallic copper by electrolyzing the Na2S-based flux with molten salt, and reduces the content of Cu2S. By reusing Na2S-based flux, Na2
This is because it has become possible to significantly reduce the actual unit consumption of S-based flux and to greatly reduce the thermal energy required for melting and heating it. An example of the technology configuration is shown below.

1) Classification of scrap and decomposition separation from copper parts 2) Production of copper-containing high-carbon molten iron by oxidation heat of carbonaceous material using a converter or carburization melting of scrap using electric energy 3) With Na2S-based flux Separation of copper from molten iron using distribution equilibrium of copper components due to contact reaction with copper-containing high carbon molten iron 4) Separation of Na2S-based flux containing Cu2S from molten iron and conversion of the copper component as metallic copper by electrolysis of the melt. Separation 5) Recycling of Na2S-based flux with reduced Cu2S content and partial replenishment of new Na2S-based flux to remove copper from copper-containing high-carbon molten iron 6) Removal of high-temperature sulfur gas generated at the anode part of the molten salt electrolyzer 400-500
By reacting with Sn plating scrap at ℃ to remove Sn, it is possible to effectively utilize high-temperature sulfur gas.

Details of the invention are shown below with reference to a schematic diagram of the process.

Copper-containing high carbon steel be melted by known means using oxidation energy or electric energy of carbonaceous materials as shown in 1-a and 1-b in Fig. The decopper removal operation is carried out by stirring and mixing contact with Na2S-based flux in the reaction vessel 2-a. At this time 120
Electric heating device 2 to maintain the reaction temperature from 0 to 1500°C
-b and a lid 2-C for contacting the atmosphere.
1. It is desirable to include a gas blowing plug 2-d for promoting stirring and mixing, and a connection 2-e with an exhaust dust collector.

After the decoppering treatment, the gold CuS, NazS-based flash flux 2 is supplied to the molten salt electrolytic bath 3-a, and the decoppered high carbon molten iron 2-g is supplied to, for example, a steelmaking furnace to be refined into steel. This operation increases the sulfur content in the molten iron, so by blowing gas from the inert gas plug 2-d, if tin is contained in the molten iron, it is possible to reduce the tin by converting it into SnS vapor or Sn vapor. The molten salt electrolytic cell has a low voltage, high current density DC power supply 3-b as shown in 3-a of FIG. 1, and has a cathode 3-c and an anode 3-d formed of graphite electrodes, for example. Because the temperature of electrolysis is high, around 1200℃, metallic copper deposits on the cathode.
Since molten copper accumulates in the bottom 3-f of the molten copper, after the molten salt electrolysis operation, the molten copper can be separated and recovered through the outlet 3-g and the Na2S slag can be recovered through the outlet 3-h. Collected N
The a2S flux 4-a is recycled 5 for the next copper removal operation. In the figure, 3-i is a gas blowing device for stirring and mixing the Na2S-based molten salt bath to promote uniformity.

The inside of the electrolytic cell is made to have an inert gas atmosphere such as Ar. High-temperature sulfur gas generated at the anode 3-d during electrolysis is reacted with scrap preheated by an induction fan 6-b installed in the duct 6-a at a temperature of 400 to 500°C. For example, a cutting hopper 6 consisting of a two-stage tank in which the reaction is carried out in a rotary kiln-shaped reaction tank 6-a, and the inside can be replaced with an inert gas afterward to maintain air insulation inside the tank.
-81 For example, a sieve-shaped separator 6-f for cooling scrap pieces after sulfurization treatment and separating SnS
Scrap 6-h, from which SnS was separated in 6-g and most of the Sn content removed, was placed in a high-carbon molten iron melting furnace 1-a for decoppering.
1-b or supplied as a raw material to a steelmaking furnace.

With this basic technology configuration, it is possible to remove copper components contained in scrap that cannot be separated by physical sorting methods.
By making it possible to recycle the basic unit of a2S flux, we have made it possible to reduce the amount by a fraction of the amount.

The present invention also requires energy for melting flux, and sulfur dioxide gas, which is generated in large quantities when Na2S slag, which is generated in large quantities, is used as a raw material in conventional processes such as copper mac manufacturing without being recycled. This is of great industrial significance as it avoids the generation of air pollutants.

The principle of the present invention allows for further improvement of efficiency by the following method. In other words, after melting copper-containing high-carbon molten iron and transferring it to the decoppering reaction tank, by changing the molten iron smelting furnace to a photomap method, etc., the copper-containing high-carbon molten iron is removed in an aerated state and the copper component is removed and reduced by molten salt electrolysis. By simultaneously pouring the molten Na2S-based flux into the copper removal reaction tank, it is possible to finish the copper removal process instantly.

Furthermore, based on basic knowledge of the chemical industry, in the reaction between copper-containing high-carbon molten iron and high-temperature Na2S-based recycled slag, electromagnetic pumps, etc. are used to carry out a countercurrent reaction operation, thereby increasing the reaction efficiency of copper removal and increasing the overall efficiency. It is also possible to improve

Next, details will be shown with examples.

[Example] 10 tons of carbon-saturated copper-containing high-carbon molten iron is produced by carburizing and melting scrap using the oxidation energy of carbonaceous materials in a top-bottom blowing converter.
On-melting was carried out. The composition of the molten iron at this time was about 0.3% copper, saturated with carbon, and a temperature of about 1450°C. This was transferred to a copper-removal reaction tank and pre-melted FeS (approximately 20%)
-Approximately 4 to 5 tons of Na2S-based flux at 1200°C or higher containing Na2S (approximately 80%) as the main component was added, the lid was closed, and the interior was made into an inert atmosphere with Ar, and a total amount of scum was removed from the bottom of the tank. Table 1 shows the results of the blowing de#l treatment.
Shown below. The conventional method that does not recycle Na2S-based flux involves one-time treatment and two-time treatment. Gold Cu after copper removal treatment
Molten salt electrolysis was carried out by connecting a graphite electrode to a DC low-voltage, high-current power source in a reaction phase in which a Na2S-based flux containing 2S was lined with graphite. This flux was used to reduce the copper content in the flux, and the copper removal treatment was carried out in two parts.

As a result, the conventional method reduces the amount of copper in molten iron from 0.3% to 0.03%.
450 kg/l in one treatment to reduce iron to 24
A Na2S-based flux of 0.0 kg/l of iron was required, but according to the present invention, if 170 kg/l of iron slag is used at one time and the treatment is carried out twice, the amount of Na2S-based slag that needs to be replenished is 50 kg/l.・It is possible to recycle Na2S-based flux in a very small amount, less than iron. The molten salt electrolytic treatment was performed in combination with two decopper removal treatments.

As shown above, the present invention reduces the amount of Na2S-based flux required in conventional technology for copper removal treatment to 450 kg to 240 kg.
It has become possible to drastically reduce the amount of iron from 50 kg/l-iron to less than 50 kg/l-iron. Also, by this operation, the average
kg/l/copper content of iron was recovered.

Table 1 Operational results of copper removal treatment* 340-50-290 kg/or more is recycled Example 2 In the invention of Example 1, the high temperature sulfur gas generated at the anode during molten salt electrolysis is guided by a draft fan and heated to 450°C. At temperatures above Sn
After contacting and reacting with the scrap of the plating material for about 10 minutes, this was cooled and passed through a vibrating sieve to peel off and separate the SnS.

After that, the residual rate of Sn in the u fraction was less than 20%, and a sufficient detining operation was possible.

[Effects of the invention] As described above, the present invention is a method that can efficiently separate copper, which is difficult to separate by physical sorting from scrap, and at the same time, it is also possible to remove tin from tin-plated scrap using high-temperature sulfur gas generated during processing. This is an extremely significant industrially significant invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a process flow to which the present invention is applied. 1-a, 1-b Copper-containing high carbon steel melting means bC: Copper-containing high carbon steel 2-a: Reaction vessel with Na2S-based flux 2-
b - Electric heating device 2-c - Lid 2-d: Gas blowing plug 2-e - Connection with exhaust dust collector 2-f: Na2S-based flux 3-a: Electrolytic treatment device 3-b, power supply 3-c Cathode 3-d: Anode 3-e: Metallic copper 3-f: Tank bottom 3-g: Molten copper outlet 3-h Nislag outlet 3-1: Gas blowing device 4-a1 recovery Na2S-based flux 4-b = recovery Copper 5: Na2S-based flux recycling 6-a: duct 6-b, term fan 6-c: preheater 6-d: reaction phase 6-e: popper 6-f8 separator 6-81 min 1111 sns 6-h ・Scrap and 4 others

Claims (1)

[Claims] 1. After carburizing and melting copper-containing scrap to make copper-containing high-carbon molten iron, the copper component in the molten iron is sulfurized by contact reaction with a molten flux whose main component is Na_2S at 1200 to 1500°C. In the method of separating and removing copper in Na_2S-based flux, the process involves separating the Na_2S-Cu_2S-based molten flux and leading it out of the system, and electrolyzing this molten flux with molten salt to separate the copper component of Cu_2S into the cathode part as metallic copper. Na_2S with reduced amount of sulfide in copper
A method for removing copper from steel, characterized by separating and recovering a flux whose main component is , and reusing it for decoppering treatment from copper-containing high-carbon molten iron. 2. Sulfur gas generated at the anode part during molten salt electrolysis of molten flux is heated to a preheated Sn-plated steel material and 400 to 500°C.
1. A method for removing copper from steel, which comprises carrying out a contact reaction at a temperature of 100 mL, followed by stripping and removing the Sn component as SnS.