Method for smelting copper through electrochemical oxidation of copper matte and synchronously depleting molten slag

Abstract

The invention provides a copper matte electrochemical oxidation copper smelting and slag synchronous depletion method which comprises the following steps: by taking molten copper slag as electrolyte, copper matte as an anode and high-melting-point metal as a cathode, applying voltage between the anode and the cathode to perform electrochemical intervention; and refining for a period of time after power failure to obtain crude copper from the anode, and discharging the molten slag as tailings after the copper content of the molten slag is reduced to 0.3% or below. The method has the following advantages: 1) gaseous sulfur generated by electrochemical oxidation at a lower layer copper matte anode interface can convert oxidation-state copper in the copper slag into copper sulfide, and dilution of molten copper slag electrolyte is promoted; the method comprises the steps of (1) melting copper slag, (2) enabling dissolved Fe3O4 in the molten copper slag to be in contact with a cathode to be reduced into FeO, reducing the viscosity of the molten slag to promote settling separation of copper matte liquid drops in the molten slag, (3) enabling electrochemical applied voltage to be extremely low, being easy to realize integrated coupling with a photovoltaic power generation system, and (4) enabling copper matte to serve as a self-consumption anode, and avoiding the problems of dissolution of a metal anode and carbon emission of a carbon anode in high-temperature molten slag.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag. Background Art

[0002] The copper smelting process causes severe disturbances at the slag-matte interface due to intense physical and chemical processes. Some matte / copper droplets enter the slag layer and disperse in the slag. When the slag viscosity is too high, the entrained matte / copper droplets are difficult to settle and difficult to enter the bottom matte molten pool, resulting in insufficient direct copper recovery in the main process. In addition, a portion of Cu in the slag is dissolved in the slag in the form of Cu2O, which is even more difficult to recover directly.

[0003] The supersaturated precipitation of Fe3O4 during the smelting process is the main reason for the difficulty in settling copper matte / copper droplets: 1) The supersaturated precipitation of Fe3O4 significantly increases the viscosity, which makes it difficult for copper / copper matte droplets in the slag to coalesce / sediment; 2) The density of Fe3O4 particles is between that of copper matte and slag, and they tend to gather at the slag-matte interface, hindering the copper matte droplets from settling to the bottom copper matte molten pool. In industry, adding reducing agents (coal blocks, pyrite, metal iron bars, etc.) to reduce Fe3O4 is often used to reduce the viscosity of the slag. However, on the one hand, the reducing agent has low utilization rate and high consumption; the gases such as CO2 or SO2 that are easily generated are not friendly to the environment; on the other hand, if the reducing agent is too much or the reducing ability is too strong, Fe3O4 is easily over-reduced to Fe, which not only reduces the grade of copper matte / copper, but also is not conducive to reducing the viscosity of the slag. It is urgent to explore a method that can selectively reduce Fe3O4 and the process is clean. Summary of the invention

[0004] In the slag-matte molten pool system, matte is a good electronic conductor, and the conversion of matte to copper is an oxidation process, so it can serve as an ideal self-oxidation anode.

[0005] Based on this, the first object of the present invention is to provide a method for electrochemically enhancing the depletion of copper slag: using copper matte as an anode and a high melting point metal as a cathode, Fe3O4 in the slag is reduced to FeO under the action of an electric field, thereby reducing the viscosity of the slag to promote the aggregation and sedimentation of copper matte droplets; on the other hand, the gaseous sulfur released during the anodic oxidation of the copper matte can convert the copper oxide in the slag into copper sulfide, further enhancing the depletion of the copper slag.

[0006] Another object of the present invention is to simultaneously realize the transformation of copper matte into metallic copper. In the process of realizing the first object, the copper matte as an anode undergoes oxidation of sulfur ions, thereby completing desulfurization and the generation of FeO, so that the anode is transformed from the copper matte phase to the metallic copper phase.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: The present invention provides a method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag, which mainly comprises the following steps: At the set reaction temperature, with molten copper slag (main components include: Cu 0.3wt%~20wt%, Fe3O47wt%~30wt%) as electrolyte, copper matte as anode, and high melting point metal as cathode, voltage is applied between the cathode and cathode for electrochemical intervention for a period of time. After power is cut off and then left to stand for a period of time, crude copper is obtained at the anode and the copper content in the slag drops to below 0.3%, which can be discharged as direct tailings.

[0008] Optionally, the main components of the anode copper matte include, by mass percentage, Cu2S 30%~100%, FeS 0.1~70%.

[0009] Optionally: the electrochemical regulation input voltage is 0.45 V to 0.65 V, and the electrochemical intervention time is 45 min to 90 min.

[0010] Optionally, the reaction temperature is set to 1250°C ~ 1350°C.

[0011] Optionally, the standing time after power failure is 20 min to 45 min.

[0012] Optionally, the high melting point metals used include tungsten, molybdenum, niobium, tantalum, vanadium, zirconium, rhenium, hafnium and alloys thereof.

[0013] The above process has the following benefits: (1) The gaseous S2 produced at the copper matte anode-slag interface can enhance the reaction and separation. The S2 gas produced by the anode in the copper matte layer during the electrochemical process can not only penetrate the Fe3O4 diaphragm at the slag-copper matte interface during the rising process, promoting the sedimentation of copper matte droplets in the slag; but also the elemental S2 gas entering the slag can sulfide Cu2O and convert it into insoluble Cu2S, which can further promote the sedimentation and recovery of the copper phase in the slag.

[0014] (2) The selective reduction of Fe3O4 in the slag to FeO at the cathode can enhance the migration and separation of copper matte droplets. Under the condition of cathode polarization, the Fe3O4 dissolved in the slag is most easily selectively reduced to FeO, which can not only increase the Fe / SiO2 ratio, but also promote the redissolution and elimination of the precipitated Fe3O4 particles, thereby reducing the slag viscosity and enhancing the migration, coalescence and sedimentation of copper matte droplets in the slag.

[0015] (3) The applied voltage required for the electrochemical intervention process is extremely low (0.2 V), and it is easy to integrate with the photovoltaic power generation system (0.4 V). Compared with the existing method of eliminating Fe3O4 by adding carbon powder and pyrite, the process is green, clean, pollution-free, highly controllable, and does not produce carbon emissions.

[0016] (4) Copper matte is an ideal self-oxidizing anode. The entire electrochemical control process does not require the addition of an inert anode. It is not troubled by the lack of stable inert anodes in the traditional molten electrochemical metallurgical system, thus eliminating the bottleneck technology of the traditional molten electrochemical metallurgical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag in the present invention. DETAILED DESCRIPTION

[0018] The following are specific implementation cases based on the technical solution of the present invention. The present invention can be better understood through the following embodiments and in combination with the accompanying drawings. It should be noted that the present invention is not limited to the following embodiments. Non-substantial modifications or changes in the form and content of the present invention made by those skilled in the art based on the principles of the present invention are within the scope of protection of the present invention.

[0019] Comparative Example 1: Weigh 100 g of copper matte (Cu2S: 50%, FeS: 50%, about 1 cm thick in the crucible) and place it at the bottom of the crucible. Then add 400 g (about 4 cm thick in the crucible) of finely ground and dried copper slag (Cu: 1.0%, Fe / SiO2=1.26) to the crucible. The crucible with slag and matte is transferred to the depletion furnace, and then heated to 1350 ℃ at a rate of 10 ℃ / min. A metal molybdenum wire is inserted into the slag as the cathode and the bottom copper matte is used as the anode. No voltage is applied and it is allowed to stand for 1 h, and then it is allowed to stand for another 0.5 h. The sample is cooled to room temperature with the furnace. The copper content of the obtained smelting tailings is still 1.0%, and Fe / SiO2=1.26.

[0020] Embodiment 1: Weigh 100 g of copper matte (Cu2S: 50%, FeS: 50%, about 1 cm thick in the crucible) and place it at the bottom of the crucible. Then add 400 g (about 4 cm thick in the crucible) of finely ground and dried copper slag (Cu: 1.0%, Fe / SiO2=1.26) to the crucible. The crucible with slag and matte is transferred to the depletion electric furnace, and then heated to 1250 ℃ at a rate of 10 ℃ / min. A metal molybdenum wire is inserted into the slag as the cathode, and the bottom copper matte is used as the anode. A voltage of 0.45V is applied for electrochemical intervention for 1 h. After the power is turned off, it is left to stand for 0.5 h, and the sample is cooled to room temperature with the furnace. The obtained smelting tailings contain 0.25% copper, Fe / SiO2=1.42, and the anode copper content is increased by 10%.

[0021] Embodiment 2: Weigh 100 g of copper matte (Cu2S: 50%, FeS: 50%, about 1 cm thick in the crucible) and place it at the bottom of the crucible. Then add 400 g (about 4 cm thick in the crucible) of finely ground and dried copper slag (Cu: 1.0%, Fe / SiO2=1.26) to the crucible. The crucible with slag and matte is transferred to the depletion electric furnace, and then heated to 1350 ℃ at a rate of 10 ℃ / min. A metal tungsten wire is inserted into the slag as the cathode, and the bottom copper matte is used as the anode. A voltage of 0.65V is applied for electrochemical intervention for 45 minutes. After the power is turned off, it is left to stand for 20 minutes, and the sample is cooled to room temperature with the furnace. The obtained smelting tailings contain 0.20% copper, Fe / SiO2=1.6, and the anode copper content is increased by 40%.

[0022] Example 3: Weigh 100 g of copper matte (Cu2S: 50%, FeS: 50%, about 1 cm thick in the crucible) and place it at the bottom of the crucible, then add 400 g (about 4 cm thick in the crucible) of finely ground and dried copper slag (Cu: 1.0%, Fe / SiO2=1.26) to the crucible. The crucible with slag and matte is transferred to a depleted electric furnace, and then heated to 1300 °C at a rate of 10 °C / min. A metal niobium wire is inserted into the slag as a cathode, and the bottom copper matte is used as an anode. A voltage of 0.55V is applied for electrochemical intervention for 45 minutes, and the power is turned off and then left to stand for 45 minutes. The sample is cooled to room temperature with the furnace. The resulting smelting tailings contain 0.23% copper, Fe / SiO2=1.51, and the anode copper content is increased by 25%.

[0023] Table 1 Comparison of some parameters of the examples The above process has the following benefits: 1) Gaseous sulfur is produced by electrochemical oxidation at the anode interface of the lower copper matte, which can convert the oxidized copper in the copper slag into copper sulfide, promoting the depletion of the molten copper slag electrolyte; 2) The dissolved Fe3O4 in the molten copper slag is reduced to FeO when in contact with the cathode, which reduces the viscosity of the slag and promotes the sedimentation and separation of the copper matte droplets in the slag; 3) The electrochemical applied voltage is extremely low, and it is easy to achieve integrated coupling with the photovoltaic power generation system; 4) Copper matte acts as a self-consumable anode, avoiding the problem of metal anode dissolution in high-temperature slag and carbon emission from carbon anode.

[0024] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for electrochemical oxidation of copper matte for copper smelting and simultaneous depletion of slag, characterized in that: The steps include: Under the set reaction temperature, with molten copper slag as electrolyte, copper matte as anode and high melting point metal as cathode, voltage is applied between the cathode and cathode for electrochemical intervention for a period of time. After power is cut off and then left to stand for a period of time, crude copper is obtained at the anode and the copper content in the slag is reduced to below 0.3%, meeting the direct tailings discharge standard.

2. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The electrochemical control input voltage is 0.45 V ~ 0.65 V.

3. The method for electrochemical copper smelting by copper matte oxidation and simultaneous slag depletion according to claim 1, characterized in that: The electrochemical control input voltage was 0.65 V.

4. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The electrochemical intervention time was 45 min to 90 min.

5. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The set reaction temperature is 1250°C ~ 1350°C.

6. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The standing time after power failure is 20 min ~ 45 min.

7. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The high melting point metals used include: tungsten, molybdenum, niobium, tantalum, vanadium, zirconium, rhenium, hafnium and their alloys.

8. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The main components of the raw copper slag include, by mass percentage: Cu 0.3%~20%, Fe3O4 7%~30%.

9. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The main components of copper matte are, by mass percentage, Cu2S 30%~100%, FeS 0.1~70%.

10. The method for electrochemical oxidation copper smelting of copper matte and simultaneous depletion of slag according to claim 1, characterized in that: The main components of copper matte include, by mass percentage: Cu2S 50%, FeS 50%.

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