Electrolytic aluminum roasting anode slotting powder recovery method

Abstract

The invention relates to the technical field of electrolytic aluminum anode manufacturing, and discloses an electrolytic aluminum roasting anode slotting powder recycling method which comprises the steps that slotting powder is input into a slotting powder bin, and the slotting powder in the slotting powder bin is evenly fed into a mixing bin; the initial fine residual powder is screened, and particles with the particle size smaller than 0.5 mm are removed; the weight difference value of the fine residual powder raw material and the initial fine residual powder is measured, and the screened fine residual powder raw material is introduced into the mixing bin; the frequency of the rotary feeder is controlled, and grooving powder which is larger than the weight difference value of the fine residual powder raw materials and the initial fine residual powder and smaller than 2% of the total raw materials is added into the mixing bin; other raw materials for producing anodes are added into the mixing bin for uniform mixing, and by means of the method, the grooving powder is effectively recycled, the use amount of the residual anodes is not reduced, and the quality of the anodes is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic aluminum anode manufacturing, and in particular to a method for recovering electrolytic aluminum roasted anode slotted powder. Background Art

[0002] During the electrolytic aluminum production process, the anode needs to be replaced regularly because of the accumulation of aluminum oxide, fluoride salts, electrolyte and other ash in the anode, which leads to a decrease in the anode electrolysis effect. The replaced anode is called a residual anode or residual electrode. In the anode manufacturing process, in order to save raw materials, the residual electrode is added to the raw materials for producing anodes, and then re-baked to form a new anode. Since the residual electrode accounts for a small proportion of the raw materials, as long as the amount of residual electrode added is controlled, the generated anode can still meet the quality requirements.

[0003] During the oxidation reaction at the anode, in order to prevent the gas generated at the bottom of the anode from accumulating at the bottom of the anode, affecting the inter-electrode conductivity, resulting in an increase in the voltage of the aluminum electrolytic cell and an increase in the power consumption, the current process is to slot the bottom of the anode along the length of the anode. This slotting method can guide more bubbles to the middle seam of the anode, strengthen the disturbance of the electrolyte area, and promote the dissolution and electrolysis reaction of aluminum oxide. Anode slotting in the aluminum electrolytic cell is conducive to stabilizing the fluctuating interface between the electrolyte and the aluminum liquid, shortening the inter-electrode distance, and reducing the power consumption. After the anode is slotted, a large amount of powder is produced, which is called slotting powder.

[0004] At present, factories have added anode scraps as raw materials to anode manufacturing. The adding method is to grind the anode scraps directly and add them to the anode raw materials without any other treatment. Because the anode scraps contain many impurities, adding the anode scraps to the raw materials will cause the quality of the anode to decrease. Therefore, in order to meet the standard requirements for anode quality, the amount of anode scraps added as raw materials per unit weight of anode must be less than the upper limit, and generally the amount of anode scraps added shall not exceed 25% of the total raw materials.

[0005] Slotted powder is only treated as waste materials; from the properties of slotted powder, it is the anode carbon block after roasting and has the same properties as the residual anode, and it has not passed through the electrolytic cell to participate in the reaction and a series of circulation processes, and has not come into contact with alumina, fluoride salts, electrolytes, etc. Therefore, its ash content is lower than that of the residual anode. Therefore, it can be used as a roasted anode raw material like the residual anode.

[0006] In actual anode production factories, the scale of production lines is fixed. When the amount of residual anodes added is not reduced, directly adding the slotting powder into the raw materials for anode manufacturing will inevitably cause an imbalance in the distribution ratio of each component in the anode manufacturing raw materials, making it impossible to guarantee the quality of the anode.

[0007] Therefore, for manufacturers with fixed production line scale and production capacity, how to use both residual anode and slotted powder as anode raw materials and ensure that the anode quality meets the requirements is a problem. Summary of the invention

[0008] The present invention aims to provide a method for recovering anode slotting powder from aluminum electrolysis roasting, so as to achieve the purpose of recycling the slotting powder without reducing the original amount of residual anode.

[0009] To achieve the above object, the present invention adopts the following technical scheme: a method for recovering powder from anode slotting of electrolytic aluminum roasting, comprising the following steps: Step 1: Input the slotting powder into the slotting powder silo; Step 2: Evenly feed the slotted powder in the slotted powder bin into the transport pipeline through a rotating feeder; Step 3: Add constant positive pressure wind force to the transport pipeline to transport the slotted powder to the mixing silo with a height of more than 25 meters; Step 4: adding a certain amount of anode scraps to be recycled, then grinding the anode scraps to obtain initial fine residual powder, sieving the initial fine residual powder to remove particles with a particle size of less than 0.5 mm, and obtaining a fine residual powder raw material; measuring the weight difference between the fine residual powder raw material and the initial fine residual powder; Step 5: introducing the fine residual powder raw material screened in step 4 into the mixing bin; Step 6: Control the frequency of the rotary feeder, and add slotted powder in the mixing bin in an amount greater than the weight difference between the fine residual powder raw material and the initial fine residual powder and less than 2% of the total raw material; Step 7: Add other raw materials for producing anodes into the mixing bin, and mix all the raw materials evenly to use as raw materials for anode molding.

[0010] The principles and advantages of this solution are: After the fine residual powder was screened through a sieve with a sieve hole diameter of 0.5mm, the weight of the fine residual powder raw material was reduced by 1.5%~2%. According to experimental analysis, the ash content of the reduced weight of the fine residual powder raw material was greater than 90%. Although the total amount of fine residual powder was reduced after screening, in order to ensure the material balance of the anode generated, when the amount of coarse residual electrode added was not reduced, slotting powder was added to the raw material; after the inventors tested the addition of slotting powder, they found that the amount of slotting powder added should be greater than the weight difference between the fine residual powder raw material and the initial fine residual powder, and less than 2% of the total raw material; the volume, density and quality of the manufactured anode all met the requirements, and the ash content was reduced by more than 0.5%.

[0011] Analysis of the reasons: The slotting powder has a small particle size, which can just fill the gaps left by the fine residual powder screened out. The remaining slotting powder also fills the particle size gaps of other anode raw materials due to its small particle size. Finally, without reducing the fine residual powder, the quality of the manufactured anodes did not decrease after the slotting powder was added.

[0012] In summary, when both fine residual powder and slotted powder are used as anode raw materials, the amount of residual anodes does not decrease. To meet the consumption of residual anodes, slotted powder is added to the raw materials, which reduces the consumption of slotted powder and solves the problem of nowhere to pile up the anode slotted powder on site, affecting the on-site environment and disposal.

[0013] By adding positive pressure wind in the transport pipeline, the anode slotting powder is brought into the mixing bin at a higher position by pneumatic conveying, and the raw materials are evenly distributed in the mixing bin. This method forms a production system with low investment, short construction period, simple equipment, low failure rate and easy maintenance and management.

[0014] By setting the motor frequency of the rotary feeder, it is ensured that the slotting powder can be accurately and stably evenly mixed into the mixing bin according to the amount in step 4, so as to achieve physical balance in the raw materials, and finally make sure that the residual pole does not reduce consumption, and the slotting powder can be recycled.

[0015] Preferably, in step one, the slotting powder is input into the slotting powder silo through a slotting powder feeding system, and the slotting powder feeding system includes a feeding pipe for negative pressure absorption of the slotting powder, one end of the feeding pipe is connected to the cyclone separator, and the other end is connected to the feeding joint.

[0016] The beneficial effect of this improvement is that the material-making joint can be connected to the outlet of the tank containing the slotting powder, and then the slotting powder is sucked into the slotting powder bin through the cyclone separator.

[0017] Preferably, in step three, the positive pressure wind force is generated by a Roots blower, and the Roots blower is connected to the transport pipeline.

[0018] The beneficial effect of this improvement is that the positive force is generated by the Roots blower to transport the slotted powder entering the transport pipeline to the mixing bin more than 25 meters high.

[0019] Preferably, in step five, a temporary storage bin for fine residual powder and a temporary storage bin for slotted powder are provided at the entrance of the mixing bin, and weight control valves are respectively provided in the temporary storage bin for fine residual powder and the temporary storage bin for slotted powder. By setting the opening conditions of the temporary storage bin for fine residual powder and the temporary storage bin for slotted powder on the weight control valves, the amount of fine residual powder and slotted powder entering the mixing bin can be more accurately adjusted.

[0020] Preferably, in step 3, a second cyclone separator is provided between the transport pipeline and the mixing bin to reduce the speed of the slotted powder in the transport pipeline. The speed reduction process reduces the interference of the positive wind force on the slotted powder when it enters the mixing bin.

[0021] Preferably, in step 4, the initial fine residual powder is ground by coarse residual pole, and then the initial fine residual powder is screened by a vibrating screen, and the mesh size of the vibrating screen is selected to be 0.5 mm.

[0022] Preferably, in step 7, a mixer is provided in the mixing bin to mix the fine residual powder, slotted powder and other anode raw materials uniformly. After the mixer is used to complete uniform mixing in the mixing bin, the raw materials in the mixing bin can be directly added to the anode forming machine to complete the forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the anode slot powder recovery system for aluminum electrolysis roasting; Figure 2 A logical step diagram of the method for recovering powder from anode slotting for aluminum electrolysis roasting. DETAILED DESCRIPTION

[0024] The following is further described in detail through specific implementation methods: The figure numbers in the drawings of the specification are: slotted powder silo 1, first cyclone separator 2, material punching joint 3, rotary feeder 4, three-way pipe 5, Roots blower 6, second cyclone separator 7, grinder 8, temporary storage bin for fine residual powder, 9 mixer 10, mixing bin 11, conveyor belt 12, temporary storage bin for slotted powder 13, transport pipeline 14, vibrating screen 15.

[0025] Embodiment 1: like Figure 1 and Figure 2 As shown, the method for recovering powder from anode slotting of aluminum electrolysis roasting comprises the following steps: Step 1 S1: input the slotted powder into the slotted powder silo 1; store the slotted powder in the slotted powder silo 1 through the slotted powder feeding system, the slotted powder feeding system includes a feeding pipe for negative pressure absorption of the slotted powder, one end of the feeding pipe is connected to the first cyclone separator 2, and the other end is connected to the feeding connector 3.

[0026] Step 2 S2: The slotted powder in the slotted powder bin 1 is evenly fed into the transport pipe 14 through the rotary feeder 4; the rotary feeder is a variable frequency speed regulating rotary feeder, which adjusts the output frequency and the rotation speed of the rotary feeder 4 to adjust the amount of slotted powder fed into the transport pipe.

[0027] Step 3 S3: The Roots blower 6 and the rotary feeder 4 are connected to the transport pipeline 14 through a three-way pipe 5. The Roots blower 6 generates a positive force to send the slotted powder in the rotary feeder 4 into the mixing bin 11 above 25 meters.

[0028] Step 4 S4: Add a certain amount of residual electrodes that need to be recycled, and then grind the residual electrodes to obtain initial fine residual powder. Before adding the fine residual powder into the mixing bin 11, the initial fine residual powder is sieved by a vibrating screen 15 to remove particles with a particle size less than 0.5 mm to obtain a fine residual powder raw material; and measure the weight difference between the fine residual powder raw material and the initial fine residual powder.

[0029] Step 5 S5: Add the sieved fine residual powder raw material into the mixing bin. Step 6 S6: Control the frequency of the rotary feeder 4 to add slotted powder in an amount greater than the weight difference between the fine residual powder and the initial fine residual powder and less than 2% of the total raw materials into the mixing bin 11; Step seven S7: fine residual powder and other anode raw materials for producing anodes are also introduced into the mixing bin 11, and the entrance of the mixing bin 11 is provided with a fine residual powder temporary storage bin 9 and a slotted powder temporary storage bin 13, and weight control valves are respectively provided in the fine residual powder temporary storage bin 9 and the slotted powder temporary storage bin 13. By setting the opening conditions of the fine residual powder temporary storage bin and the slotted powder temporary storage bin on the weight control valve, the amount of fine residual powder and slotted powder entering the mixing bin can be more accurately adjusted.

[0030] A second cyclone separator 7 is provided between the transport pipeline 14 and the mixing bin 11 to reduce the speed of the slotted powder in the transport pipeline 14. The fine residual powder and other anode raw materials introduced need to be ground by the grinder 8 first, and the particle size of the fine residual powder after grinding is less than 3 mm. Since more than 90% of the particle size of the slotted powder is less than 1 mm, it is not suitable for re-grinding, so the fine residual powder and other anode raw materials are pre-ground.

[0031] A mixer 10 is provided in the mixing bin 11 to mix the fine residual powder, slotted powder and other anode raw materials uniformly. After the mixer 10 completes uniform mixing in the mixing bin, the anode raw materials in the mixing bin can be conveyed to the subsequent process through the conveyor belt 12 below.

[0032] Embodiment 2: This embodiment tests the amount of slotting powder added, and the slotting powder is added to the system at a maximum ratio of 2%. After the fine residual powder is screened through a sieve with a sieve hole diameter of 0.5mm, the weight of the fine residual powder raw material is reduced by 1.5%~2%. According to experimental analysis, 90% of the weight reduction of the fine residual powder raw material is ash. Although the total amount of the fine residual powder is reduced after screening, the fine residual powder entering the mixing bin 11 is first screened to remove particles smaller than 0.5mm in the fine residual powder. The fine residual powder, slotting powder and other anode raw materials are mixed in the mixing bin. After measuring, more than 90% of the slotting powder particle size is below 0.5mm, and the particles smaller than 0.5mm in the fine residual powder are removed. The slotting powder can just fill the gaps screened out by the fine residual powder. In addition, the remaining slotting powder is filled in the particle size gaps of other anode raw materials, so that after adding the slotting powder, not only does the consumption of residual poles not decrease, but the quality of the manufactured anodes is also greatly improved.

[0033] According to the addition of 2% of slotting powder, 18 tons of slotting powder can be consumed every day; the roasting workshop produces about 15-20 tons of slotting powder every day, which can basically consume the slotting powder amount of the day, and at this time, more than 4,000 tons of residual poles can be saved every year.

[0034] The method can accurately mix the slotting powder and the fine residual powder, so that a certain amount of slotting powder can be added without reducing the amount of residual anodes, so that both the slotting powder and the residual anodes are consumed.

[0035] The consumption of anode scraps is the same as that before slotting powder is added, so that the consumption and production of anode scraps and slotting powder are balanced, further solving the problem of excessive accumulation of anode slotting powder and anode scraps on site.

[0036] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for recovering powder from anode slotting of electrolytic aluminum roasting, characterized in that: Step 1: Input the slotting powder into the slotting powder silo; Step 2: Evenly feed the slotted powder in the slotted powder bin into the transport pipeline through a rotating feeder; Step 3: Add constant positive pressure wind force to the transport pipeline to transport the slotted powder to the mixing silo with a height of more than 25 meters; Step 4: adding a certain amount of anode scraps to be recycled, then grinding the anode scraps to obtain initial fine residual powder, sieving the initial fine residual powder to remove particles with a particle size of less than 0.5 mm, and obtaining a fine residual powder raw material; measuring the weight difference between the fine residual powder raw material and the initial fine residual powder; Step 5: introducing the fine residual powder raw material screened in step 4 into the mixing bin; Step 6: Control the frequency of the rotary feeder, and add slotted powder in the mixing bin in an amount greater than the weight difference between the fine residual powder raw material and the initial fine residual powder and less than 2% of the total raw material; Step 7: Add other raw materials for producing anodes into the mixing bin, and mix all the raw materials evenly to use as raw materials for anode molding.

2. The method for recovering powder from anode slotting of aluminum electrolysis according to claim 1, characterized in that: In step one, the slotting powder is input into the slotting powder bin through a slotting powder punching system, wherein the slotting powder punching system comprises a punching pipe for negative pressure absorption of the slotting powder, wherein one end of the punching pipe is connected to a cyclone separator, and the other end is connected to a punching joint.

3. The method for recovering powder from anode slotting of aluminum electrolysis according to claim 2, characterized in that: In step three, the positive pressure wind force is generated by a Roots blower, and the Roots blower is connected to the transport pipeline.

4. The method for recovering powder from anode slotting of aluminum electrolysis roasting according to claim 3, characterized in that: In step five, a temporary storage bin for fine residual powder and a temporary storage bin for slotted powder are provided at the entrance of the mixing bin, and weight control valves are provided in the temporary storage bin for fine residual powder and the temporary storage bin for slotted powder, respectively, and the opening conditions of the temporary storage bin for fine residual powder and the temporary storage bin for slotted powder are set by the weight control valves.

5. The method for recovering powder from anode slotting of aluminum electrolysis according to claim 4, characterized in that: In step three, a second cyclone separator is arranged between the transport pipeline and the mixing bin to reduce the speed of the slotted powder in the transport pipeline.

6. The method for recovering powder from anode slotting of aluminum electrolysis roasting according to claim 5, characterized in that: In step 4, the initial fine residual powder is ground by the coarse residual electrode, and then the initial fine residual powder is screened by a vibrating screen, and the mesh size of the vibrating screen is selected to be 0.5 mm.

7. The method for recovering powder from anode slotting of aluminum electrolysis according to claim 6, characterized in that: In step seven, the fine residual powder, slotted powder and other anode raw materials are mixed uniformly by setting a mixer in the mixing bin.

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