WO2018058952A1

WO2018058952A1 - Method of removing carbon in copper-containing molten iron by using vortex to draw in limestone

Info

Publication number: WO2018058952A1
Application number: PCT/CN2017/082309
Authority: WO
Inventors: 张廷安; 豆志河; 张保敬; 张子木; 刘燕; 牛丽萍; 王东兴; 吕国志
Original assignee: 东北大学
Priority date: 2016-09-27
Filing date: 2017-04-28
Publication date: 2018-04-05
Also published as: CN106319154A; AU2017333111A1; AU2017333111B2; CN106319154B

Abstract

A method of removing carbon in a copper-containing molten iron by using a vortex to draw in limestone. The method belongs to the technical field of metallurgy, and comprises the specific steps of: (1) feeding copper-containing molten iron, obtained by adding a carbonaceous reducing agent into copper slag for reduction, and ensuring that the temperature is ≥1450°C, into an induction furnace; (2) centrally stirring the copper-containing molten iron to form a vortex with a height-diameter ratio of 0.5 to 2.5; (3) spraying limestone powder into the center of the vortex while the central stirring continues, and performing eccentric stirring after the limestone powder has been sprayed so as to allow more homogeneous mixing of generated CO₂ in the vortex; (4) enabling the limestone powder to be directly drawn into the molten iron by the vortex to fully react with the molten iron and to obtain decarbonized copper-containing molten iron and molten slag; and (5) discharging the decarbonized copper-containing molten iron and the molten slag in different layers. The method is simple, requires little investment, is capable of saving energy and protecting the environment and is low in cost, has high economic value, achieves decarbonization, and protects a copper element in the copper-containing molten iron against loss through burning.

Description

Method for removing carbon from copper-containing iron water by eddy current entrapped into limestone

Technical field:

The invention belongs to the technical field of metallurgy, and particularly relates to a method for removing carbon from copper-containing iron water by vortex enrollment into limestone.

Background technique:

Each ton of copper produced will produce 2.2 tons of copper slag. With the rapid development of copper smelting technology, the stock of copper slag is also greatly increased. Copper slag contains a large amount of valuable metal elements. At present, the utilization of copper slag is concentrated on copper extraction and iron extraction alone. The simultaneous use of copper and iron is limited to copper-iron alloy. Most of the extraction of copper and iron elements uses carbonaceous reducing agents to reduce oxides and sulfides in copper slag. To ensure the reduction effect, most of the carbonaceous reducing agents are added in excess, which makes the obtained copper-iron alloy contain a large amount of carbon, to a large extent. The use value of the alloy is lowered, and the copper-containing molten iron is used for smelting the copper-containing antibacterial stainless steel to perform the decarburization process.

Industrial decarburization methods include ordinary oxygen decarburization and vacuum decarburization. Although the degree of decarburization is different, all of them are reacted with carbon in the alloy to achieve the decarburization effect. This method is used in hot metal steelmaking. Widely used in the process. For copper-containing molten iron, the passage of oxygen causes the copper element to burn out.

O ₂ +[Cu]=Cu ₂ O

The relatively low copper content is further reduced, and the application of copper-containing molten iron needs to ensure a certain copper element content. The content of copper element in the martensite copper-containing antibacterial stainless steel is 2.5-4.0%, and the copper content is too low and needs to be in the subsequent process. The addition of copper alloy is not worth the candle.

In the industry, the addition of solid additives is mostly suspended on the surface of the melt, which is difficult to fully contact with the slag bath, the additive utilization rate is extremely low, and some of the less dense additives are highly volatile, causing very serious environmental pollution. Therefore, it is necessary to find a new decarburizer to remove carbon from copper-containing iron water, which not only effectively removes carbon from the alloy, but also protects a small amount of valuable elements in the alloy. A new way of adding is needed to increase the utilization of decarburizers.

Patent No. 201210104356.0 proposes a new KR desulfurization stirring method, which involves desulfurization outside the hot metal furnace before the converter, and the desulfurization agent on the surface of the molten iron is mixed into the molten iron by the rotary agitation of the stirrer, but the decarburization is not involved. field. The patent application number 201510802460.0 proposes a method of RH forced oxygen decarburization, which can reduce the carbon content to 9 ppm under vacuum conditions, but only involves decarburization of molten iron, and does not involve decarburization of copper-containing molten iron. The application No. 201510471169.X proposes a method for smelting high-carbon high-strength molten iron in an argon-oxygen decarburization furnace, and does not involve decarburization of copper-containing molten iron. The application No. 201610144809.0 proposes a method of mixing and pulverizing copper slag by stirring, and stirring to form a vortex, which has a very good reduction effect, but does not involve the field of decarburization.

Summary of the invention:

In view of the insufficiency of existing solid additive addition methods and oxygen decarburization, the present invention proposes a method for removing turbulent wind into limestone to remove carbon from copper-containing iron. The method uses a central stirring to stir and stir the molten iron to generate a vortex, and the powdered limestone is added to the center of the vortex and is immediately vortexed into the depth of the molten iron, fully mixed and reacted with the molten iron, and the limestone is rapidly decomposed into calcium oxide and CO ₂ at a high temperature, CO ₂ reacts with carbon in molten iron to produce CO, and CO ₂ acts as a weak oxidizing gas and does not react with copper. Calcium oxide can promote the dephosphorization and desiliconization process, and the slag floats on the surface of the melt to protect.

To achieve the above object, the present invention adopts the following technical solutions:

A method for removing vortex from limestone to remove carbon in copper-containing iron water comprises the following steps:

(1) Introducing copper-containing molten iron into the induction furnace to ensure that the temperature of the copper-containing molten iron is ≥ 1450 ° C;

(2) stirring copper-containing molten iron to form a vortex having a height to diameter ratio of 0.5 to 2.5;

(3) Spray limestone powder into the center of the vortex, during the spraying process, continue the stirring of step (2), and keep the vortex temperature ≥ 1450 ° C. After the limestone powder is sprayed, continue stirring for 20 to 40 minutes; Mass ratio, limestone powder: copper-containing molten iron = (1 ~ 4): 10;

(4) The limestone powder is directly entangled in the molten iron and fully contacted with the molten iron and reacted to obtain the decarburized copper-containing molten iron and molten slag;

(5) The copper-containing molten iron and slag after decarburization are discharged in layers.

In the step (1), the copper-containing molten iron is obtained by adding a copper slag to the carbonaceous reducing agent, and the temperature of the copper-containing molten iron is 1450 to 1650 °C.

In the step (1), the mass percentage of carbon in the copper-containing iron water is 2.0 to 6.0%.

In the step (1), the copper-containing mass percentage in the copper-containing iron water is 4.68 to 5.88%.

In the step (1), the method for ensuring the temperature of the copper-containing molten iron ≥ 1450 ° C is that the induction furnace itself is heated.

In the step (1), the induction furnace includes a slag discharge port and a discharge iron outlet, the lower portion of one side of the induction furnace is provided with a discharge port, and the upper portion of the induction furnace is provided with a slag discharge port. ;

The induction furnace is provided with a stirring paddle, a stirring paddle lifting system, a wind hood, a flue gas purifying system, a waste heat recovery system and a washing tower; the stirring paddle is disposed inside the induction furnace; and the wind hood is disposed in the induction furnace Above, the inlet of the flue gas purification system is connected to the hood through a pipeline, and the inlet of the waste heat recovery system is connected to the outlet of the flue gas purification system through a pipeline, and the inlet of the scrubbing tower passes through the pipeline and the waste heat recovery system The outlet of the washing tower is connected to the atmosphere; the stirring paddle is connected with a stirring paddle lifting system for replacing the stirring paddle; and the powder spraying device is used for spraying the limestone powder.

In the step (2), the stirring method is center stirring, and the stirring paddle is inserted into the 1/3 to 1/2 of the height of the copper-containing molten iron surface, and the center stirring is performed, and the center stirring speed is 50 to 200 r/min.

In the step (3), after the limestone powder is blown, the stirring is performed by eccentric stirring, the eccentric stirring speed is 50 to 200 r/min, and the eccentricity is 0.1 to 0.8, in order to diffuse the generated CO ₂ . Mix more with the vortex.

In the step (4), the carbon content in the copper-containing iron water after decarburization is ≤0.2% by mass.

In the step (4), the mass percentage of copper in the copper-containing molten iron after decarburization is Cu: 4.67 to 5.87%.

In the step (4), the main component of the slag is CaO.

In the step (4), after the decarburized copper-containing molten iron and the slag are obtained, a gas is generated, and the gas is mainly the remaining CO ₂ , which is sent to the flue gas purification system via the hood, and after the purification treatment, the residual heat The recovery system recovers the waste heat and recovers it with a Ca(OH) ₂ solution through a washing tower, and obtains a CaCO ₃ precipitate as a limestone powder raw material and returns it to the induction furnace for reuse.

In the step (5), in the induction furnace, the upper layer is slag, and the lower layer is decarburized copper-containing molten iron, and the slag is discharged from the slag discharge port, and the copper-containing molten iron is discharged from the discharge port after decarburization.

Decarburization principle:

CaCO ₃ =CaO+CO ₂ (g)

CO ₂ +[C]=2CO(g)

The beneficial effects of the invention:

(1) By stirring, the center of the agitator stirs and rotates to generate a vortex in the molten iron. The limestone which is added to the surface of the molten iron by the swirling flow is immediately wound into the depth of the molten iron, and the limestone is rapidly decomposed to produce CO ₂ and copper-containing molten iron. The reaction of [C] reaches the decarburization effect.

(2) CO ₂ is a weak oxidizing gas, which does not oxidize copper while decarburizing, not only achieves the effect of decarburization, but also avoids the burning of copper.

(3) The decarburizing agent adopts cheaper limestone and is added by stirring. The added limestone can be quickly mixed into the molten iron, and the reaction is rapid and complete, and the construction period is short.

(4) By adding limestone, the carbon content in the molten iron can be effectively reduced, and the oxidation condition caused by the generated CO ₂ contributes to the removal of phosphorus and silicon in the molten iron, so that the carbon content of the molten iron can be reduced to less than 0.2%, which is in line with steelmaking. Hot metal demand does not reduce the copper content of the melt.

(5) The method is simple in process, adding a stirring system to the induction furnace, with low investment, energy saving and environmental protection, low cost and high economic value.

BRIEF DESCRIPTION OF THE DRAWINGS:

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the structure of an induction furnace system using the method of the present invention, wherein: 1-slag discharge port; 2-row iron nozzle; 3-propeller paddle; 4-propeller paddle lifting system; 5-dusting device; ; 7 - flue gas purification system; 8 - waste heat recovery system; 9 - washing tower.

detailed description:

The present invention will be further described in detail below with reference to the embodiments.

Example 1

The copper-containing molten iron used in the present embodiment has specific compositions as shown in Table 1.

Table 1 Content of each element in copper-containing molten iron (mass fraction, %)

The schematic diagram of the structure of the induction furnace system used in this embodiment is shown in FIG.

(1) After adding the copper slag to the carbonaceous reducing agent, the copper-containing molten iron obtained by the reduction is heated at a temperature of 1450 ° C and a mass of 20 t, and is added to the induction furnace to control the temperature of the copper-containing molten iron to be 1450 ° C, and the copper-containing molten iron is contained. The mass percentage of C is 2.0%, and the mass percentage of Cu is 4.68%;

(2) adjusting the stirring paddle 3 to be inserted into the 1/3 of the height of the copper-containing molten iron surface, centrally stirring the copper-containing molten iron, and stirring at a speed of 50 r/min to form a vortex having a height-to-diameter ratio of 0.5;

According to the reaction needs, through the stirring paddle lifting system 4, the stirring paddle 3 is replaced;

(3) 2t limestone powder is sprayed from the powder spraying device 5 into the center of the vortex, and the center stirring is continued, and the vortex temperature is maintained at 1450 ° C through the induction furnace, and the eccentric stirring is changed after the limestone powder is sprayed, and the eccentricity is 0.1. The eccentric stirring time is 20 min, which makes the generated CO ₂ diffuse and is more fully mixed with the vortex;

(4) The limestone powder is directly entangled in the molten iron and is in contact with the molten iron and reacted to obtain the decarburized copper-containing molten iron and slag, and the remaining CO _{2 is} sent to the flue gas purification system 7 via the hood 6 to purify After the treatment, the waste heat is recovered by the waste heat recovery system 8, and is recovered by the Ca(OH) ₂ solution through the washing tower 9, and the CaCO ₃ precipitate is returned to the induction furnace as a limestone powder raw material, and reused;

(5) In the induction furnace, the upper layer is slag, the main component of the slag is CaO, and the lower layer is decarburized copper-containing molten iron. The decarburized copper-containing molten iron is discharged from the iron discharge port 2, and the slag is discharged from the slag discharge port. 1 discharge, wherein, after decarburization, the content of C in the copper-containing iron water is 0.08%, the mass percentage of Cu in the copper-containing iron water after decarburization is 4.67%, the mass fraction containing P is 0.105%, and the mass fraction containing Si is 0.215%. .

Example 2

The copper-containing molten iron used in the present embodiment has specific compositions as shown in Table 2.

Table 2 Contents of each element in copper-containing molten iron (mass fraction, %)

(1) After adding copper slag to the carbonaceous reducing agent, the copper-containing molten iron obtained by reduction is heated at a temperature of 1500 ° C and a mass of 20 t, and is added to an induction furnace to control the temperature of the copper-containing molten iron to be 1500 ° C. The mass percentage of C is 3.2%, and the mass percentage of Cu is 5.06%;

(2) adjusting the stirring paddle 3 to be inserted into 1/3 of the height of the liquid surface of the copper-containing molten iron, centrally stirring the copper-containing molten iron, and stirring at a speed of 100 r/min to form a vortex having a height-to-diameter ratio of 1.5;

(3) 4t limestone powder is sprayed from the powder spraying device 5 into the center of the vortex, and the center stirring is continued, and the vortex temperature is maintained at 1500 ° C through the induction furnace, and the eccentric stirring is changed after the limestone is blown, and the eccentricity is 0.3. The eccentric stirring time is 30 min, which makes the generated CO ₂ diffuse and is more fully mixed with the vortex;

(5) In the induction furnace, the upper layer is slag, the main component of the slag is CaO, and the lower layer is decarburized copper-containing molten iron. The decarburized copper-containing molten iron is discharged from the iron discharge port 2, and the slag is discharged from the slag discharge port. 1 discharge, wherein, after decarburization, the content of C in the copper-containing iron water is 0.13%, the mass percentage of Cu in the copper-containing iron water after decarburization is 5.04%, the mass fraction of P is 0.08%, and the mass fraction of Si is 0.135%. .

Example 3

The copper-containing molten iron used in the present embodiment is as shown in Table 3.

Table 3 Content of each element in copper-containing molten iron (mass fraction, %)

(1) After adding copper slag to the carbonaceous reducing agent, the copper-containing molten iron obtained by the reduction is heated at a temperature of 1550 ° C and a mass of 30 t, and is added to the induction furnace to control the temperature of the copper-containing molten iron to be 1550 ° C. The mass percentage of C is 4.5%, and the mass percentage of Cu is 5.24%;

(2) adjusting the stirring paddle 3 to be inserted into the liquid level of the copper-containing molten iron at 1/2, and stirring the copper-containing molten iron at a center speed of 150 r/min to form a vortex having a height-to-diameter ratio of 2.0;

(3) The 9t limestone powder is sprayed from the dusting device 5 into the center of the vortex, and the center stirring is continued, and the vortex temperature is maintained at 1550 ° C through the induction furnace, and the eccentric stirring is changed after the limestone is sprayed, and the eccentricity is 0.6. The eccentric stirring time is 35 min, which makes the generated CO ₂ diffuse and mixes with the vortex more fully;

(4) The limestone powder is directly entangled in the molten iron and is in contact with the molten iron and reacts to form decarburized copper-containing molten iron and slag, and the remaining CO _{2 is} removed to the flue gas purification system 7 via the hood 6 to purify After the treatment, the waste heat is recovered by the waste heat recovery system 8, and is recovered by the Ca(OH) ₂ solution through the washing tower 9, and the CaCO ₃ precipitate is returned to the induction furnace as a limestone powder raw material, and reused;

(5) In the induction furnace, the upper layer is slag, the main component of the slag is CaO, and the lower layer is decarburized copper-containing molten iron. The decarburized copper-containing molten iron is discharged from the iron discharge port 2, and the slag is discharged from the slag discharge port. 1 discharge, wherein, after decarburization, the content of C in the copper-containing iron water is 0.10%, the mass percentage of Cu in the copper-containing iron water after decarburization is 5.23%, the mass fraction containing P is 0.11%, and the mass fraction containing Si is 0.205%. .

Example 4

The copper-containing molten iron used in the present embodiment has specific compositions as shown in Table 4.

Table 4 Content of each element in copper-containing molten iron (mass fraction, %)

(1) After adding the copper slag to the carbonaceous reducing agent, the copper-containing molten iron obtained by the reduction is heated at a temperature of 1650 ° C and a mass of 20 t, and is added to the induction furnace to control the temperature of the copper-containing molten iron to be 1650 ° C, and the copper-containing molten iron is contained. The mass percentage of C is 6.0%, and the mass percentage of Cu is 5.88%;

(2) adjusting the stirring paddle 3 to be inserted into the liquid level of the copper-containing molten iron at a height of 1/2, and stirring the copper-containing molten iron at a center speed of 200 r/min to form a vortex having a height-to-diameter ratio of 2.5;

(3) The 8t limestone powder is sprayed from the dusting device 5 into the center of the vortex, and the center stirring is continued, and the vortex temperature is maintained at 1650 ° C through the induction furnace, and the eccentric stirring is changed after the limestone is sprayed, and the eccentricity is 0.8. The eccentric stirring time is 40 min, and the generated CO _{2 is} diffused and mixed with the vortex more fully;

(5) In the induction furnace, the upper layer is slag, the main component of the slag is CaO, and the lower layer is decarburized copper-containing molten iron. The decarburized copper-containing molten iron is discharged from the iron discharge port 2, and the slag is discharged from the slag discharge port. 1 discharge, wherein, after decarburization, the content of C in the copper-containing iron water is 0.2%, and the mass percentage of Cu in the copper-containing iron water after decarburization is 5.87%, and the mass fraction containing P is 0.092%, including The Si mass fraction was 0.165%.

Claims

A method for removing turbulent wind into limestone to remove carbon in copper-containing iron water, characterized in that it comprises the following steps:

(1) Introducing copper-containing molten iron into the induction furnace to ensure that the temperature of the copper-containing molten iron is ≥ 1450 ° C;

(2) stirring copper-containing molten iron to form a vortex having a height to diameter ratio of 0.5 to 2.5;

(3) Spray limestone powder into the center of the vortex, during the spraying process, continue the stirring of step (2), and keep the vortex temperature ≥ 1450 ° C. After the limestone powder is sprayed, continue stirring for 20 to 40 minutes; Mass ratio, limestone powder: copper-containing molten iron = (1 ~ 4): 10;

(4) The limestone powder is directly entangled in the molten iron and fully contacted with the molten iron and reacted to obtain the decarburized copper-containing molten iron and molten slag;

(5) The copper-containing molten iron and slag after decarburization are discharged in layers.
The method for removing carbon from copper-containing iron in a vortex entrained limestone according to claim 1, wherein in the step (1), the copper-containing molten iron is obtained by adding a carbonaceous reducing agent to the copper slag, and The temperature of copper and iron water is 1450 ~ 1650 °C.
The method for removing carbon from copper-containing iron in a vortex entrained limestone according to claim 1, wherein in the step (1), the induction furnace comprises a slag discharge port and a discharge iron port, and the induction furnace a lower portion of one side of the induction furnace is provided with a slag discharge port;

The induction furnace is provided with a stirring paddle, a stirring paddle lifting system, a wind hood, a flue gas purifying system, a waste heat recovery system and a washing tower; the stirring paddle is disposed inside the induction furnace; and the wind hood is disposed in the induction furnace Above, the inlet of the flue gas purification system is connected to the hood through a pipeline, and the inlet of the waste heat recovery system is connected to the outlet of the flue gas purification system through a pipeline, and the scrubber passes through the pipeline and the waste heat recovery system. An outlet connection; the agitating paddle is connected with a paddle lifting system for replacing the agitating paddle; and the powder spraying device is used for injecting limestone powder.
The method for removing carbon from copper-containing iron in a vortex entrained limestone according to claim 3, wherein in the step (2), the stirring mode is center stirring, and the stirring paddle is inserted into the copper-containing molten iron surface. Center stirring is performed at 1/3 to 1/2 of the height, and the center stirring speed is 50 to 200 r/min.
The method for removing carbon from copper-containing iron in a vortex entrained limestone according to claim 1, wherein in the step (3), after the limestone powder is sprayed, the stirring is eccentric stirring, and the eccentric stirring is performed. The speed is 50 to 200 r/min, and the eccentricity is 0.1 to 0.8.
The method for removing carbon from copper-containing iron in a vortex entrained limestone according to claim 1, wherein in the step (4), the carbon-containing mass percentage of the copper-containing molten iron after decarburization is ≤0.2%.
The method for removing carbon from copper-containing iron in a vortex entrained limestone according to claim 3, wherein in the step (4), the copper-containing molten iron and the slag after decarburization are obtained, and the remaining The CO 2 is sent to the flue gas purification system via the hood, and after the purification treatment, the waste heat is recovered by the waste heat recovery system, and is recovered by the Ca(OH) 2 solution through the washing tower to obtain the CaCO 3 precipitate as the limestone powder raw material and returned to the induction furnace. In, reuse.
The method for removing carbon from copper-containing molten iron by vortex entrainment of limestone according to claim 3, wherein in the step (5), in the induction furnace, the upper layer is slag, and the lower layer is decarburized. Copper-iron water discharges the slag from the slag discharge port, and the copper-containing molten iron is discharged from the discharge port after decarburization.