Purification and bismuth removal method for lead electrolysis residual polar plate washing water

Abstract

The invention provides a method for purifying and removing bismuth from lead electrolysis residual polar plate washing water, which comprises the following steps: washing a residual polar plate obtained after electrolysis of an anode plate, collecting anode mud on the surface of the residual polar plate, and carrying out filter pressing on the anode mud to obtain the washing water; soaking the washed residual polar plate in washing water until the bismuth ion content in the washing water is less than 0.02 g / L; the distance between the residual polar plates is 20-95 mm, and every 2-4 m < 3 > of the washing water is used for soaking 45-120 residual polar plates. By adopting the purification and bismuth removal method provided by the invention, the bismuth ion Bi of the produced washing water is less than or equal to 0.02 g / L, and the washing water completely meets the process requirements of electrolyte; and the risk that the Bi exceeds the standard and pollutes the electrolyte is reduced, resource recovery of lead ions (300 mg / L) and silicofluoride acid (300 mg / L) in the washing water is achieved, the waste water treatment cost is reduced, and the cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of lead electrolytic refining, and in particular to a method for purifying and removing bismuth from washing water of residual plates of lead electrolysis. Background Art

[0002] With the popularization of the process of washing the residual anodes of lead electrolysis, the reuse of washing water has become a pain point in the industry. Since the washing water after washing the residual anode plates is rich in a large amount of lead ions, silicic acid and bismuth ions, if it is not recycled, it will cause a waste of resources and increase production costs. If it is recycled, the excessive bismuth ions will affect the quality of the electrolyte and thus affect the quality of the lead. Chinese patent CN103938228B discloses the use of lead plates to purify the washing water, but this solution occupies a large amount of lead inventory, the operation process is relatively complicated, the energy consumption is high, and the anode plates can only be returned to the pot after purification, which affects the direct yield. Therefore, finding an efficient method for purifying washing water has become a favorable way for enterprises to reduce costs and increase efficiency. Summary of the invention

[0003] In view of this, the purpose of the present invention is to propose a method for purifying and removing bismuth from washing water of lead electrolysis residual plates, wherein the bismuth ions Bi of the produced washing water are ≤0.02g / L, which effectively reduces the risk of excessive Bi ions contaminating the electrolyte.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A method for purifying and removing bismuth from lead electrolysis residual plate washing water comprises the following steps:

[0006] (1) washing the anode plate scrap obtained after electrolysis of the anode plate, collecting the anode mud on the surface of the anode plate, and obtaining washing water by filtering the anode mud;

[0007] (2) Soak the washed butted plates in washing water until the bismuth ion content in the washing water is less than 0.02 g / L;

[0008] In step (2), the spacing between the residual plates is 20 to 95 mm, and the residual plates are spaced every 2 to 4 m. 3 The washing water soaks 45 to 120 pieces of the residual plates.

[0009] The key steps of the process of the present invention are the surface cleaning and soaking time of the butt plates. If the surface of the butt plates is not cleaned, the residual anode mud will enter the washing water, affecting the quality of the washing water. At the same time, the anode mud attached to the surface of the butt plates will also affect the contact surface between the washing water and the butt plates, reducing the purification effect of the soaking reaction.

[0010] The soaking time is based on the fluctuation of the bismuth ion content in the washing water. If the soaking time is too short, the bismuth in the washing water cannot be effectively purified to meet the standards; if the purification time is too long, the production cycle will be affected.

[0011] A further solution is that in step (2), the soaking time is 20 to 100 hours.

[0012] A further solution is that the number of the residual plates is 45 to 50 and the time for soaking the residual plates in washing water is 70 to 100 hours.

[0013] A further solution is that the spacing between the residual plates is 80-95 mm and the washing water consumption is 3m 3 .

[0014] A further solution is that the number of the residual plates is 90 to 95 and the time for soaking the residual plates in washing water is 20 to 50 hours.

[0015] A further solution is to set the spacing of the residual plates to 45-50 mm and the washing water consumption to 3 m 3 The time for soaking the residual plates with washing water is 40 to 50 hours; or the spacing between the residual plates is 45 to 50 mm, and the amount of washing water is 2 m 3 The time for soaking the residual plates in washing water is 20 to 30 hours.

[0016] A further solution is that the number of the residual plates is 115 to 125, and the time for soaking the residual plates in washing water is 40 to 50 hours.

[0017] A further solution is to use a residual plate spacing of 20 to 50 mm and a washing water volume of 3 m 3 .

[0018] A further solution is that the dimensions of the anode plate are: lower length 650-670 mm, upper length 990-1010 mm, height 950-970 mm, and thickness 28-32 mm; the dimensions of the residual plate are: lower length 650-670 mm, upper length 990-1010 mm, height 950-970 mm, and thickness 8-12 mm.

[0019] A further solution is that in step (1), during the electrolysis, the anode plate is crude lead, the electrolyte is lead fluorsilicate, and the electrolysis cycle is 4 to 6 days.

[0020] A further solution is that the components of the anode plate include: Pb 95% to 97%, Cu 0.05% to 0.08%, Bi1% to 2%, Sb 1% to 3% and As 0.5% to 1%; the components of the lead fluorosilicate include: total acid 150 to 190 g / L, free acid 70 to 100 g / L, Pb 90 to 110 g / L and Bi 0.5 to 1 mg / L.

[0021] If the washing water is directly returned to the electrolyte without removing bismuth, the quality of the finished lead will be unqualified. If it is directly abandoned and discharged, it will incur wastewater treatment costs for the company. Based on the workshop's monthly production of 1,350 cubic meters of washing water, the wastewater treatment cost is 2 yuan / cubic meter, resulting in a monthly wastewater treatment cost of 2,700 yuan.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] By adopting the purification and bismuth removal method proposed in the present invention, the bismuth ion Bi of the produced washing water is less than or equal to 0.02 g / L, and the washing water fully meets the process requirements of the electrolyte; not only the risk of excessive Bi contamination of the electrolyte is reduced, but also the resource recovery of lead ions (300 mg / L) and silicic acid (300 mg / L) in the washing water is realized, the wastewater treatment fee is reduced, and the cost is reduced.

[0024] Compared with the traditional process of directly returning the washing water to the electrolyte system without treatment, the present invention purifies the washing water, effectively realizes the recovery of lead ions and silicic acid, ensures the quality of the electrolyte, reduces or even avoids the purification frequency of the electrode liquid after long-term use, and ensures the quality of the lead-acid products.

[0025] The method for purifying and removing bismuth by washing water provided by the present invention is simple to operate, does not require electricity, and saves energy consumption. There is no problem that the washing water cannot be used for electrolysis after the anode plate is purified. The resource utilization rate is high and the economic benefit is remarkable. DETAILED DESCRIPTION

[0026] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0027] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0028] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0029] The electrolytic cell used in the bismuth removal process in the embodiment of the present invention is not used for electrolysis, but is used for soaking the residual plates with washing water.

[0030] The replacement reaction method of the spent plates and washing water provided by the present invention can adjust the amount of washing water, as well as the size, spacing and number of the spent plates according to the production site of the enterprise, so as to fully utilize the site, reduce production costs and achieve the effect of maximizing benefits.

[0031] The dimensions of the anode plate of the embodiment of the present invention are: 660 mm in length at the bottom, 1000 mm in total including the upper part and the ears, 960 mm in height, and 30 mm in thickness. The dimensions of the residual plate are the same as those of the anode plate, but its thickness is about 10 mm.

[0032] Example 1

[0033] 47 qualified anode plates (Pb 95.0%, Cu 0.078%, Bi 1.66%, Sb 2.38%, As0.75%) and 46 cathode plates (Pb 99%) were hoisted into the electrolytic cell with a spacing of 95mm, and the lead fluoride silicate electrolyte (total acid 173g / L, free acid 86g / L, Pb 93g / L, Bi 0.73mg / L) was circulated, and the current was 2000-7500A for electrolysis. After one cycle of electrolysis (5 days), the lead electrolysis process will send the precipitated lead to the refining pot for refining to produce finished electric lead. After one cycle of electrolysis, the anode becomes a residual plate, which is transferred to the residual plate washing machine by a crane for washing. The anode mud on the surface of the residual plate is washed into the anode mud slurry pool. The anode sludge obtained after the anode slurry is filtered through the filter press is sent to Guiye for reduction smelting, and the washing water after the filter press is pumped into the washing water pool. Prepare 6 rows of 54 electrolytic cells for purifying washing water, and pump the washing water into the electrolytic cells with a pump. Each electrolytic cell is equipped with 3m 3 Wash water, then load the cleaned residual plates into 46 pieces at a spacing of 95mm and put them into the electrolytic cell. After soaking the residual plates in washing water for 48-96h, take samples for testing. If the washing water Bi is ≤0.02g / L, the residual plates can be lifted out. The washing water meets the electrolyte requirements and is pumped into the low-level electrolyte tank for electrolysis.

[0034] Table 1 Effect of spacing and number of residual plates on bismuth ion content in washing water

[0035]

[0036] It can be seen from Table 1 above that the smaller the spacing between the residual plates and the greater the number, the better the bismuth removal effect after soaking in washing water. When soaked in washing water for 48 hours, the bismuth ion content is reduced to 0.015g / L. Considering the convenience and safety of loading the residual plates, 46 residual plates are selected and the soaking time of washing water is appropriately extended. The washing water can also meet the requirements of the electrolyte. The electrolyte can be returned for continued electrolysis, thereby improving resource utilization, reducing wastewater treatment costs, and reducing costs.

[0037] Example 2

[0038] 47 qualified anode plates (Pb 96.0%, Cu 0.062%, Bi 1.73%, Sb 2.07%, As0.88%) and 46 cathode plates (Pb 99%) were hoisted into the electrolytic cell with a spacing of 95mm, and the lead fluoride silicate electrolyte (total acid 173g / L, free acid 86g / L, Pb 93g / L, Bi 0.73mg / L) was circulated, and the current was 2000-7500A for electrolysis. After one cycle of electrolysis (5 days), the lead electrolysis process will send the precipitated lead to the refining pot for refining to produce finished electric lead. After one cycle of electrolysis, the anode becomes a residual plate, which is transferred to the residual plate washing machine by a crane for washing. The anode mud on the surface of the residual plate is washed into the anode mud slurry pool. The anode mud residue obtained after the anode mud liquid is filtered through the filter press is sent to Guiye for reduction smelting, and the washing water after filtration is pumped into the washing water pool.

[0039] Solution 2-1: 3m 3 The amount of washing water is enough to load 120 cleaned residual plates with a spacing of 47mm between them. After soaking the residual plates in washing water for 48-96h, take samples for testing and if Bi≤0.02g / L, the residual plates can be hoisted out. The washing water meets the electrolyte requirements and is pumped into the low-level electrolyte tank for electrolysis.

[0040] After testing, the bismuth ion content decreased to 0.0102 g / L after immersion for 24 hours, and decreased to 0.0087 g / L after immersion for 48 hours.

[0041] Solution 2-2: 3m 3 The amount of washing water is enough to load 120 cleaned residual plates, with the residual plates spaced 23mm apart.

[0042] After testing, the bismuth ion content decreased to 0.0356 g / L after immersion for 24 hours, and decreased to 0.0275 g / L after immersion for 48 hours.

[0043] Example 3

[0044] 47 qualified anode plates (Pb 95.7%, Cu 0.075%, Bi 1.93%, Sb 2.63%, As0.92%) and 46 cathode plates (Pb 99%) were hoisted into the electrolytic cell with a spacing of 95mm, and the lead fluoride silicate electrolyte (total acid 181g / L, free acid 93g / L, Pb 107g / L, Bi 0.86mg / L) was circulated, and the current was 2000-7500A for electrolysis. After one cycle of electrolysis (5 days), the lead electrolysis process will send the precipitated lead to the refining pot for refining to produce finished electric lead. After one cycle of electrolysis, the anode becomes a residual plate, which is transferred to the residual plate washing machine by a crane for washing. The anode mud on the surface of the residual plate is washed into the anode mud slurry pool. The anode mud residue obtained after the anode mud liquid is filtered through the filter press is sent to Guiye for reduction smelting, and the washing water after filtration is pumped into the washing water pool.

[0045] Press 2m 3 The amount of washing water is enough to load 92 cleaned residual plates with a spacing of 47mm between them. After soaking the residual plates in washing water for 48-96h, take samples for testing and if Bi≤0.02g / L, the residual plates can be hoisted out. The washing water meets the requirements of the electrolyte and is pumped into the low-level electrolyte tank for electrolysis.

[0046] After testing, the bismuth ion content decreased to 0.0358 g / L after immersion for 12 hours, and decreased to 0.0142 g / L after immersion for 24 hours.

[0047] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for purifying and removing bismuth from washing water of lead electrolysis residual plates, characterized in that: The steps include: (1) washing the anode plate scrap obtained after electrolysis of the anode plate, collecting the anode mud on the surface of the anode plate, and obtaining washing water by filtering the anode mud; (2) Soak the washed butted plates in washing water until the bismuth ion content in the washing water is less than 0.02 g / L; In step (2), the spacing between the residual plates is 20 to 95 mm, and the residual plates are spaced every 2 to 4 m. 3 The washing water soaks 45 to 120 pieces of the residual plates.

2. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 1, characterized in that: In step (2), the soaking time is 20 to 100 hours.

3. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 2, characterized in that: The number of the residual plates is 45 to 50, and the time for soaking the residual plates in washing water is 70 to 100 hours.

4. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 3, characterized in that: The spacing between the residual plates is 80-95 mm, and the amount of water used for washing is 3 m 3 .

5. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 2, characterized in that: The number of the residual plates is 90 to 95, and the time for soaking the residual plates in washing water is 20 to 50 hours.

6. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 5, characterized in that: The spacing between the residual plates is 45-50 mm, and the amount of water used for washing is 3 m 3 The time for soaking the residual plates with washing water is 40 to 50 hours; or the spacing between the residual plates is 45 to 50 mm, and the amount of washing water is 2 m 3 The time for soaking the residual plates in washing water is 20 to 30 hours.

7. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 2, characterized in that: The number of the residual plates is 115 to 125, and the time for soaking the residual plates in washing water is 40 to 50 hours.

8. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 7, characterized in that: The spacing between the residual plates is 20 to 50 mm, and the amount of water used for washing is 3 m 3 .

9. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 1, characterized in that: The dimensions of the anode plate are: lower length 650-670mm, upper length 990-1010mm, height 950-970mm, thickness 28-32mm; the dimensions of the residual plate are: lower length 650-670mm, upper length 990-1010mm, height 950-970mm, thickness 8-12mm.

10. The method for purifying and removing bismuth from lead electrolysis residual plate washing water according to claim 1, characterized in that: In step (1), in the electrolysis, the anode plate is crude lead, the electrolyte is lead fluorsilicate, and the electrolysis cycle is 4 to 6 days; The components of the anode plate include, by weight, 95% to 97% Pb, 0.05% to 0.08% Cu, 1% to 2% Bi, 1% to 3% Sb and 0.5% to 1% As; the components of the lead fluorosilicate include, 150 to 190 g / L total acid, 70 to 100 g / L free acid, 90 to 110 g / L Pb and 0.5 to 1 mg / L Bi.

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