Method for promoting selective reduction of Fe3O4 in copper slag by carbon-containing anode through electrochemical process

Abstract

The invention provides a method for promoting selective reduction of Fe3O4 in copper slag by a carbon-containing anode through an electrochemical process, which comprises the following steps: weighing a certain amount of finely ground and dried copper slag, placing the copper slag in a crucible, transferring the crucible with the copper slag into a dilution electric furnace, and heating to a specific reaction temperature at a speed of 10 DEG C / min to obtain molten copper slag; then inserting a pretreated graphite anode and an inert high-melting-point metal cathode, and introducing a certain voltage to carry out electrochemical regulation and control; standing for a period of time after powering off, and cooling the sample to room temperature along with the furnace; the lower layer of the obtained sample is copper matte, and the upper layer is slag tailings. According to the method, the carbon-containing anode is adopted to replace pulverized coal and is combined with an electrochemical method for regulation and control, on one hand, the carbon-containing anode can penetrate into the copper slag, and the reducible depth of the slag is increased; and meanwhile, continuous work of the carbon-containing anode is guaranteed through intervention of an electrochemical method, and the problem that the utilization rate of the industrial pulverized coal reduced copper slag is low is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for promoting the selective reduction of Fe3O4 in copper slag by a carbon-containing anode using an electrochemical method. Background Art

[0002] Strengthening the recovery of metallic copper in copper slag is an important part of ensuring the safety of copper resources. 80% of the copper matte / copper in copper slag is difficult to recover due to the high viscosity of the molten slag, which makes it difficult for the copper matte / copper droplets entrained in the slag to settle.

[0003] The supersaturated precipitation of Fe3O4 during the smelting process is the main reason for the difficulty in settling copper matte / copper droplets: the supersaturated precipitation of Fe3O4 significantly increases the viscosity, making it difficult for the copper / copper matte droplets in the slag to coalesce / sediment. In industry, coal powder / coal blocks are often used to reduce Fe3O4 to FeO and add quartz to generate fayalite to prevent FeO from being re-oxidized, thereby reducing the solubility of Fe3O4 in the slag. However, the density of coal powder (1.75 g / cm 3 ) is much smaller than the density of slag (3.7 g / cm 3 ), after being put into the slag, it floats on the surface of the slag liquid. On the one hand, it is difficult for the pulverized coal to penetrate into the slag for reduction, and the reduction effect is poor; on the other hand, the industrial copper smelting process is dynamic, and the pulverized coal enters the furnace and floats on the surface of the slag liquid and overflows the slag discharge port with the flowing slag liquid, and the utilization rate is low. In order to reduce the Fe3O4 in the slag as much as possible and reduce the slag viscosity, it is urgent to improve the utilization rate of pulverized coal. Summary of the invention

[0004] In order to solve the problem of utilization rate of ferroferric oxide in copper slag reduced by coal powder in industry, the object of the present invention is to provide a method for promoting separation of copper slag and copper matte by electrochemically regulating graphite reduction.

[0005] The above objectives are achieved through the following schemes: A certain amount of finely ground and dried copper slag (main components include Cu 0.3wt%~20wt%, Fe3O47wt%~30wt%) is weighed and placed in a crucible. The crucible with copper slag is transferred into a depleted electric furnace and heated to a specific temperature at a rate of 10 ℃ / min to obtain molten copper slag; then a carbon anode and an inert high-melting-point metal cathode are inserted, and a certain voltage is passed to maintain the system temperature for electrochemical regulation; after power is turned off and left to stand for a period of time, the sample is cooled to room temperature with the furnace; the lower layer of the obtained sample is copper matte, and the upper layer is molten slag tailings.

[0006] Preferably, the specific reaction temperature is 1250° C. to 1350° C. The specific reaction temperature for electrochemical regulation is 1250° C. to 1350° C., and the electrochemical regulation time is 30 min to 120 min.

[0007] Preferably, the inert high melting point metal includes: tungsten, molybdenum, niobium, tantalum, vanadium, zirconium, rhenium, hafnium and alloys thereof.

[0008] Preferably, the electrochemical regulation input voltage is 0.60 V to 0.71 V; the electrochemical regulation time is 30 min to 120 min. The electrochemical regulation time is 30 min to 120 min.

[0009] Preferably, the standing time after power failure is 15 min to 60 min.

[0010] Preferably, the anode rod and cathode rod are pretreated by covering their outer layers with a refractory protective sheath.

[0011] Functions and Effects of the Invention In view of the problems of low utilization rate of copper reduction by coal powder and insufficient reduction degree of copper slag, the present invention provides a method for promoting the selective reduction of Fe3O4 in copper slag by a carbon-containing anode by an electrochemical method. During the electrochemical regulation process, the cathode and anode reactions are as follows: The benefits include: (1) Using carbon-containing anodes to replace coal powder combined with electrochemical control. On the one hand, the carbon-containing anode can penetrate deep into the copper slag, increasing the reducible depth of the slag; at the same time, the intervention of the electrochemical method ensures the continuous operation of the carbon-containing anode, solving the problem of low utilization rate of coal powder reduction of copper slag in industry; (2) By controlling the input voltage to regulate the electrochemical reaction process and control the selective reduction of ferroferric oxide to FeO, it is not only possible to reduce the input of SiO2 during the smelting process, but also to avoid the phenomenon of over-reduction of ferroferric oxide, reduce the viscosity of the slag, and enhance the migration, coalescence and sedimentation of copper matte droplets in the slag; (3) The copper content of the molten tailings after electrochemical intervention shall not exceed 0.3%; (4) In copper smelting, the insertion of carbon-containing anodes into the molten slag can fix the carbon in the slag instead of allowing it to float on the surface of the liquid slag, thereby reducing the amount of carbon that overflows from the slag discharge port with the flowing liquid slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of electrochemical regulation of carbon-containing anode to promote copper slag-matte separation. DETAILED DESCRIPTION

[0013] 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.

[0014] Embodiment 1: Weigh 400 g of finely ground and dried copper slag (Cu: 2.0%, magnetic iron: 12%) and pour it into the crucible and transfer it to the depletion electric furnace. At the same time, place the tungsten wire and carbon anode with a corundum tube sleeve on the slag surface. Then, heat it to 1250℃ at a rate of 10℃ / min to obtain molten copper slag, and insert the tungsten wire (cathode) and carbon anode into the slag at the same time. After the slag stabilizes, maintain the system temperature and pass a voltage of 0.6 V for electrochemical intervention for 30 minutes. After the power is turned off, let it stand for 15 minutes, and the sample will cool down to room temperature with the furnace. The copper content of the obtained smelting tailings is reduced to 0.29%, and the magnetic iron content is 6%.

[0015] Embodiment 2: Weigh 400 g of finely ground and dried copper slag (Cu: 2.0%, magnetic iron: 12%) and pour it into the crucible and transfer it to the depletion electric furnace. At the same time, the molybdenum wire and carbon anode with a corundum tube sleeve are placed above the slag surface. Subsequently, the temperature is raised to 1350℃ at a rate of 10℃ / min to obtain molten copper slag, and the molybdenum wire (cathode) and carbon anode are inserted into the slag at the same time. After the slag stabilizes, the system temperature is maintained and a voltage of 0.71V is applied for electrochemical intervention for 120 min. After the power is turned off, it is left to stand for 60 minutes. The sample is cooled to room temperature with the furnace. The copper content of the obtained smelting tailings slag is reduced to 0.20%, and the magnetic iron content is 3%.

[0016] Embodiment 3: Weigh 400 g of finely ground and dried copper slag (Cu: 2.0%, magnetic iron: 12%) and pour it into a crucible and transfer it to a depletion electric furnace. At the same time, place the tantalum wire and carbon anode with a magnesium oxide refractory sleeve on the slag surface. Subsequently, the temperature is raised to 1280 °C at a rate of 10 °C / min to obtain molten copper slag, and the tantalum wire (cathode) and carbon anode are inserted into the slag at the same time. After the slag stabilizes, maintain the system temperature and pass a voltage of 0.65 V for electrochemical intervention for 60 minutes. After the power is turned off, let it stand for 45 minutes, and the sample is cooled to room temperature with the furnace. The copper content of the obtained smelting tailings slag is reduced to 0.25%, and the magnetic iron content is 5%.

[0017] Comparative Example 1: Weigh 400 g of finely ground and dried copper slag (Cu: 2.0%, magnetic iron: 12%) and pour it into the crucible and transfer it to the atmosphere furnace. At the same time, place the molybdenum wire and carbon anode with a corundum tube sleeve on the slag surface. Then, heat it to 1280℃ at a rate of 10℃ / min to obtain molten copper slag. Insert the molybdenum wire and carbon anode into the slag at the same time without applying voltage. After the slag stabilizes, keep it warm for 60 minutes, then let it stand for 60 minutes. The sample is cooled to room temperature with the furnace. The copper content of the smelting tailings slag is reduced to 1.5%, and the magnetic iron content is 10%.

[0018] Comparative Example 2: 400 g of finely ground and dried copper slag (Cu: 2.0%, magnetic iron: 12%) was weighed and poured into a crucible and then transferred into an atmosphere furnace. The temperature was raised to 1280 °C at a rate of 10 °C / min, and carbon powder accounting for 4% of the mass of the copper slag was added as a reducing agent. After reacting for 120 minutes, the temperature was kept warm for 60 minutes. The sample was cooled to room temperature with the furnace, and the copper content of the smelting tailings was reduced to 0.9%, and the magnetic iron content was 8%.

[0019] Table 1 Comparison of some parameters of the examples From Comparative Examples 1 and 2, it can be seen that: without adding electrochemical intervention, the reduction effect is significantly improved by using a carbon-containing anode instead of carbon powder, the carbon utilization rate is improved, and the copper content in the slag after the reaction is equivalent to the copper content in the tailings after further beneficiation after the cooling and crushing of the slag in the existing industrial process.

[0020] Comparative Example 2 is the main method used in the existing copper slag depletion. During the test, the effect of spraying carbon powder into the slag is better than directly using a rod-shaped carbon anode (Comparative Example 1). Spraying carbon powder into the slag is beneficial to increasing the contact area between the carbon powder and the slag and promoting the reduction reaction. At the same time, in this method, carbon mainly plays a role in conducting electricity and generating CO reducing gas (beneficial to promoting depletion) during anode oxidation. Therefore, when the carbon anode enters the slag, a corundum sleeve needs to be placed on the outside, and the contact area with the slag is small. When no electricity is applied, the carbon anode only retains its reduction effect, so the depletion effect is inferior to the existing industrial method.

[0021] 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 promoting the selective reduction of Fe3O4 in copper slag by electrochemical method using a carbon-containing anode, characterized in that: The steps include: A certain amount of finely ground and dried copper slag is weighed and placed in a crucible. The crucible with the copper slag is transferred into a depleted electric furnace and heated to a specific temperature at a rate of 10 ℃ / min to obtain molten copper slag; then a carbon anode and an inert high-melting-point metal cathode are inserted, and a certain voltage is passed for electrochemical regulation; after the power is turned off, the sample is left to stand for a period of time, and the temperature of the sample is cooled to room temperature along with the furnace; the lower layer of the obtained sample is copper matte, and the upper layer is molten slag tailings, and the copper content of the tailings does not exceed 0.3%.

2. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: The specific reaction temperature is 1250 ℃ ~ 1350 ℃.

3. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: The inert high melting point metals used include: tungsten, molybdenum, niobium, tantalum, vanadium, zirconium, rhenium, hafnium and their alloys.

4. The method according to claim 1, wherein: The electrochemical control input voltage is 0.60 V ~ 0.71 V.

5. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: The electrochemical regulation time is 30 min ~ 120 min.

6. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: The standing time after power failure is 15 min ~ 60 min.

7. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: A refractory protective sheath is placed on the outer layer of the anode rod and the cathode rod.

8. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: The refractory material protective sleeve is a corundum sleeve.

9. The method of electrochemically promoting the selective reduction of Fe3O4 in copper slag by carbon-containing anode according to claim 1, characterized in that: The main components of the raw copper slag include Cu 0.3%~20% and Fe3O4 7%~30% by mass percentage.

Images