A method for direct recovery of lead and simultaneous enrichment of copper from copper dross

Abstract

The application provides a method for directly recovering lead from copper dross and synchronously enriching copper, and belongs to the technical field of copper dross treatment. The method uses the waste heat of copper dross produced by copper removal through crude lead fractional crystallization as an initial heat source, inputs an external heat source for secondary heating, and deposits liquid metal lead at the bottom under low-speed stirring, so that the copper-rich residue floats on the upper layer, and lead and slag are separated. Finally, liquid metal lead with a lead content of more than 94% is recovered from the lead discharge port at the bottom of the pot, and the residue is fished out. The application fully utilizes the waste heat of copper dross, does not need high-temperature smelting of a converting furnace or a reduction furnace, the lead metal recovery rate can reach 56-64%, and the lead metal can be directly used for producing lead anode plates. The copper content of the residue is increased to 10-60wt%, and the residue can be directly sold or reused as copper matte, so that the application has the advantages of short process, low energy consumption, low carbon emission, and synchronous recovery of gold and silver.

Description

Technical Field

[0001] This invention belongs to the field of copper slag treatment technology, specifically relating to a method for directly recovering lead and simultaneously enriching copper from copper slag. Background Technology

[0002] Copper dross is an important intermediate product produced during the pyrometallurgical refining of crude lead, through the smelting and precipitation of copper. Copper dross typically contains 5–35 wt% Cu and 60–90 wt% Pb (of which approximately 80% of the lead exists in elemental form), and is also rich in precious metals such as silver and gold. Efficiently separating and recovering lead and copper from copper dross is a key step in achieving comprehensive resource utilization and reducing smelting costs.

[0003] Currently, the mainstream method for industrial copper dross treatment remains traditional pyrometallurgical smelting. Pyrometallurgical processes typically require sending the copper dross into a blowing furnace or reduction furnace for high-temperature smelting, which has significant drawbacks: First, it relies on multiple processes such as blowing and reduction furnaces, resulting in a complex process, long processing cycles, and high equipment investment and maintenance costs. Second, blowing and reduction furnaces usually operate at temperatures of 950–1400°C, requiring additional heating during the high-temperature smelting process, leading to high energy consumption and carbon emissions. Third, high-temperature smelting causes a large amount of volatile metals such as lead and zinc to volatilize, resulting in metal entrainment losses and the generation of toxic volatile substances such as arsenic and antimony, increasing the burden on flue gas and acid mist treatment and creating significant environmental pressure. Some studies have attempted to use hydrometallurgical processes for recycling, but these processes are lengthy, generate large amounts of wastewater, and low-temperature reduction often results in incomplete lead-copper separation due to insufficient reaction kinetics, leading to low recovery rates and hindering industrial application.

[0004] Therefore, developing a copper slag treatment technology that can significantly reduce processing temperature while ensuring efficient separation of lead and copper, and that is simple and environmentally friendly, to directly recover lead metal and optimize the utilization value of the residue, has significant industrial value and practical significance. Summary of the Invention

[0005] To address the problems of complex processes, high equipment dependence, high energy consumption, and high carbon emissions in existing copper slag treatment processes, the present invention aims to provide a direct recovery method that combines the waste heat from the copper removal process with special additives to achieve efficient lead separation and simultaneous copper enrichment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for directly recovering lead and simultaneously enriching copper from copper slag, comprising the following steps: (1) Under conventional crude lead smelting conditions, the copper dross produced after copper removal in the copper removal pot (with a processing capacity of 150 tons) (with a yield of 8~15wt%, containing 60~90wt% Pb and 5~35wt% Cu, and a temperature of 350~400℃) will be transferred to the separation pot (with a processing capacity of 10~20 tons) to utilize the residual heat of the copper dross as the initial heat source. The separation pot is located next to the copper removal pot and is positioned higher than the copper removal pot level, which facilitates operation, shortens the copper dross transfer time, reduces heat loss, improves heat utilization efficiency, and reduces transportation energy consumption. (2) Input an external heat source, place the mixer in the center of the small pot, with the blades 2-5cm away from the inner wall of the small pot, start the mixer to stir, heat the copper slag to a certain temperature and then keep it warm. This process makes full use of the residual heat of melting and reduces the input of additional energy. Add special additives and stir to separate the mechanically mixed lead from the slag. Since the density of lead is greater than that of copper slag, the liquid metal lead settles to the bottom of the separation pot due to the density difference, and the residue floats on the liquid metal lead. (3) Open the lead outlet at the bottom of the separation pot and use gravity to allow the liquid metal lead to flow into the copper melting pot to recover the liquid metal lead; after the liquid metal lead in the separation pot is discharged, use the slag removal device to remove the residue in the pot.

[0007] Preferably, in step (2), the external heat source is natural gas heating and / or electric heating.

[0008] Preferably, in step (2), the stirring method is low-speed stirring, the stirring speed is 10~30r / min, and the stirring time is 30~60min.

[0009] Preferably, in step (2), the temperature of the heating and heat preservation process is 550~750℃.

[0010] Preferably, in step (2), the special additive is a combination of borax-boric acid composite flux, ferrous oxide-manganese oxide composite flux, and fluorite.

[0011] Further preferred embodiments include a borax-boric acid composite flux with a borax-boric acid mass ratio of 2:1; a ferrous oxide-manganese oxide composite flux with a ferrous oxide-manganese oxide mass ratio of 3:2; and fluorite with a CaF2 mass percentage of ≥75%.

[0012] More preferably, the amount of borax-boric acid compound flux added is 0.3-1.1% of the mass of copper dross; the amount of ferrous oxide-manganese oxide compound flux added is 1.3-1.7% of the mass of copper dross; and the amount of fluorite added is 0.8-1.2% of the mass of copper dross.

[0013] Preferably, in step (3), the liquid metal lead does not need to be melted and cast into crude lead ingots. It can be directly returned to the crude lead melting and copper removal system to produce lead anode plates, making more efficient use of the enthalpy of liquid metal lead and saving the energy of melting crude lead ingots. The residue can be directly sold as matte or put into the converter to produce matte after being removed by the slag removal device. During the separation process of lead liquid and residue, precious metals such as gold and silver are enriched with lead liquid or residue respectively, which is convenient for subsequent extraction.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention only melts lead metal in copper slag, requiring a lower temperature. It uses a specific ratio of composite additives to encapsulate fine impurities in the slag, fixing arsenic and antimony impurities and preventing them from re-incorporating into the lead liquid. At the same time, it can reduce the density of the copper phase, making it easier for the copper phase to separate from the lead liquid. This method does not require traditional high-temperature treatment steps such as blowing furnaces and reduction furnaces, reducing equipment occupation and operation, simplifying the process, and reducing the emissions of flue gas and acid mist generated by traditional high-temperature smelting. Carbon emissions are reduced by about 30%, which has certain environmental benefits.

[0015] (2) This invention directly recovers liquid metallic lead with a lead content greater than 94wt% through physical separation, with a lead recovery rate of 56-64% and a copper content in the residue of 10-60wt%, significantly improving resource utilization. The residue obtained by this invention can be directly sold or reused as matte, reducing intermediate costs and simultaneously recovering gold and silver, further improving overall benefits and having certain economic benefits.

[0016] (3) The present invention utilizes the residual heat of melting and precipitation to achieve lead-copper separation in copper slag through secondary heating, which reduces energy consumption by about 40% compared with the traditional pyrometallurgical process (950~1400℃). Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 (1) After the crude lead is melted and copper is removed, the copper dross produced contains 90wt% Pb and 5wt% Cu; the temperature is 350℃; the copper dross is transferred to the separation pot using a dross removal device, and the dross removal is stopped when the thickness of the copper dross on the surface of the melting and copper removal pot is less than 3cm.

[0020] (2) Use an electric heating device to heat the copper slag, start the mixer and stir the copper slag at a speed of 10 r / min to facilitate heat transfer and uniform heating of the copper slag; place the mixer in the center of the separation pot, with the blades 5 cm away from the inner wall of the separation pot; when the temperature of the copper slag rises to 550℃, reduce the electric heating power to keep the copper slag in a heat preservation state, and at this time increase the stirring speed of the mixer to 30 r / min to break the structure of the copper slag through the blades and accelerate the lead liquid to emerge from the inside of the copper slag, but it does not separate from the copper slag; then, based on the quality of the copper slag, add composite additives in the following proportions: 0.3% of borax-boric acid composite flux; 1.3% of ferrous oxide-manganese oxide composite agent; and 0.8% of fluorite; the mixer continues to run, and the lead liquid and copper slag gradually separate and slowly flow into the bottom of the separation pot, and stir for 30 minutes.

[0021] (3) Open the lead outlet at the bottom of the pot and let the lead liquid flow into the copper removal pot. After the lead liquid has stopped flowing for more than 5 minutes, stop stirring and use the slag removal device to remove the residue.

[0022] In this embodiment, the residue contains 10.2 wt% Cu and the liquid metallic lead contains 95.30 wt% Pb; 79% of the elemental lead in the copper slag flows into the copper smelting pot, and the lead recovery rate can reach 64%.

[0023] Example 2 (1) After the crude lead is melted and copper is removed, the copper dross produced contains 60wt% Pb and 35wt% Cu; the temperature is 400℃; the copper dross is transferred to the separation pot using a dross removal device, and the dross removal is stopped when the thickness of the copper dross on the surface of the melting and copper removal pot is less than 3cm.

[0024] (2) Use natural gas to heat the copper slag, start the mixer and stir the copper slag at a speed of 10 r / min to facilitate heat transfer and uniform heating of the copper slag; place the mixer in the center of the separation pot, with the blades 5 cm away from the inner wall of the separation pot; when the temperature of the copper slag rises to 600℃, reduce the natural gas flow rate to keep the copper slag in a heat preservation state, and at this time increase the stirring speed of the mixer to 20 r / min to break the structure of the copper slag through the blades and accelerate the lead liquid to emerge from the inside of the copper slag, but it does not separate from the copper slag; then, based on the quality of the copper slag, add composite additives in the following proportions: 0.8% of borax-boric acid composite flux; 1.7% of ferrous oxide-manganese oxide composite agent; and 1.2% of fluorite; the mixer continues to run, and the lead liquid and copper slag gradually separate and slowly flow into the bottom of the separation pot, and stir for 60 minutes.

[0025] (3) Open the lead outlet at the bottom of the pot and let the lead liquid flow into the copper removal pot. After the lead liquid has stopped flowing for more than 5 minutes, stop stirring and use the slag removal device to remove the residue.

[0026] In this embodiment, the residue contains 53.78 wt% Cu; the liquid metallic lead contains 94.72 wt% Pb; 70% of the elemental lead in the copper slag flows into the copper smelting pot, and the lead recovery rate can reach 56%.

[0027] Example 3 (1) After the crude lead is melted and copper is removed, the copper dross produced contains 60wt% Pb and 35wt% Cu; the temperature is 400℃; the copper dross is transferred to the separation pot using a dross removal device, and the dross removal is stopped when the thickness of the copper dross on the surface of the melting and copper removal pot is less than 3cm.

[0028] (2) Use natural gas to heat the copper slag, start the mixer and stir the copper slag at a speed of 10 r / min to facilitate heat transfer and uniform heating of the copper slag; place the mixer in the center of the separation pot, with the blades 5 cm away from the inner wall of the separation pot; when the temperature of the copper slag rises to 750℃, reduce the natural gas flow rate to keep the copper slag in a heat preservation state, and at this time increase the stirring speed of the mixer to 30 r / min to break the structure of the copper slag through the blades and accelerate the lead liquid to emerge from the inside of the copper slag, but it does not separate from the copper slag; then, based on the quality of the copper slag, add composite additives in the following proportions: borax-boric acid composite flux at 1.1%; ferrous oxide-manganese oxide composite flux at 1.5%; fluorite at 1%; the mixer continues to run, and the lead liquid and copper slag gradually separate and slowly flow into the bottom of the separation pot, and stir for 60 minutes.

[0029] (3) Open the lead outlet at the bottom of the pot and let the lead liquid flow into the copper removal pot. After the lead liquid has stopped flowing for more than 5 minutes, stop stirring and use the slag removal device to remove the residue.

[0030] In this embodiment, the residue contains 58.56 wt% Cu; the liquid metallic lead contains 94.52 wt% Pb; 80% of the elemental lead in the copper slag flows into the copper smelting pot, and the lead recovery rate can reach 64.5%.

[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that no composite additive is added; the remaining steps and processes are exactly the same as in Example 1, as follows: (1) After the crude lead is melted and copper is removed, the copper dross produced contains 90wt% Pb and 5wt% Cu; the temperature is 350℃; the copper dross is transferred to the separation pot using a dross removal device, and the dross removal is stopped when the thickness of the copper dross on the surface of the melting and copper removal pot is less than 3cm.

[0032] (2) Use an electric heating device to heat the copper slag. Start the mixer and stir the copper slag at a speed of 10 r / min to facilitate heat transfer and uniform heating of the copper slag. Place the mixer in the center of the separation pot with the blades 5 cm away from the inner wall of the separation pot. When the temperature of the copper slag rises to 550℃, reduce the electric heating power to keep the copper slag in a heat preservation state. At this time, increase the stirring speed of the mixer to 30 r / min to break the structure of the copper slag through the blades and accelerate the lead liquid to emerge from the inside of the copper slag. The mixer continues to run, and the lead liquid and copper slag gradually separate and slowly flow into the bottom of the separation pot. Stir for 30 minutes.

[0033] (3) Open the lead outlet at the bottom of the pot and let the lead liquid flow into the copper removal pot. After the lead liquid has stopped flowing for more than 5 minutes, stop stirring and use the slag removal device to remove the residue.

[0034] In this comparative example, the residue contained 8.22 wt% Cu; the liquid metallic lead contained 91.06 wt% Pb; 62% of the elemental lead in the copper slag flowed into the copper removal pot, and the lead recovery rate was 49.6%.

[0035] As demonstrated in Examples 1, 2, and 3, this invention effectively separates and enriches lead and copper in copper slag under low-temperature conditions (550-750℃) by employing a specific ratio of composite additives, directly recovering liquid metallic lead with a lead content greater than 94wt%, achieving a lead recovery rate of 56-64%, and increasing the copper content in the residue to 10-60wt%. Specifically, compared to Comparative Example 1, Example 1 showed an increase of 1.98wt% in Cu content in the residue, 4.24wt% in Pb content in the liquid metallic lead, and a 14.4% increase in lead recovery rate.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for directly recovering lead and simultaneously enriching copper from copper slag, characterized in that, Includes the following steps: (1) Transfer the copper slag produced by melting and removing copper from crude lead to a separation pot and use the residual heat in the copper slag as the initial heat source; (2) Input an external heat source to raise the temperature, keep it warm, add composite additives, stir, so that the liquid metal lead is deposited to the bottom of the separation pot, and the residue floats on the liquid metal lead; (3) Recover liquid metallic lead through the lead drain port at the bottom of the separation pot and remove the residue.

2. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 1, characterized in that: In step (2), the external heat source is natural gas heating and / or electric heating.

3. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 1, characterized in that: In step (2), the stirring method is low-speed stirring, the stirring speed is 10~30r / min, and the stirring time is 30~60min.

4. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 1, characterized in that: In step (2), the temperature during the heating and heat preservation process is 550~750℃.

5. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 1, characterized in that: In step (2), the composite additive is a combination of borax-boric acid composite flux, ferrous oxide-manganese oxide composite flux, and fluorite.

6. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 5, characterized in that: The mass ratio of borax to boric acid in the borax-boric acid composite flux is 2:1; the mass ratio of ferrous oxide to manganese oxide in the ferrous oxide-manganese oxide composite flux is 3:2; and the mass percentage of CaF2 in the fluorite is ≥75%.

7. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 5, characterized in that: The amount of the borax-boric acid composite flux added is 0.3-1.1% of the mass of the copper slag; the amount of the ferrous oxide-manganese oxide composite flux added is 1.3-1.7% of the mass of the copper slag; and the amount of the fluorite added is 0.8-1.2% of the mass of the copper slag.

8. The method for directly recovering lead and simultaneously enriching copper from copper slag according to claim 1, characterized in that: In step (3), liquid lead is returned to the crude lead melting and copper removal system to produce lead anode plates; the residue is removed using a slag removal device and can be sold directly as matte or used in a converter to produce matte.

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