CN113881967B - Impurity removal method for lead electrolyte - Google Patents

Abstract

The invention provides a lead electrolyte impurity removal method, which comprises the following steps: taking an electrolytic tank with the total amount of less than 2 percent of the electrolytic tank as an impurity removal electrolytic tank, and taking the rest electrolytic tank as a product electrolytic tank; carrying out partial insulation covering treatment on the surface of a cathode in an impurity removal electrolytic cell to obtain the cathode with the reduced electrolytic surface area; loading the anode and the cathode with the reduced electrolysis surface area into an impurity removal electrolytic cell to obtain an impurity removal electrolytic cell to be electrolyzed; and electrolyzing the impurity-removing electrolytic tank to be electrolyzed and the product electrolytic tank in the lead electrolyte to separate out impurity ions and lead ions in the lead electrolyte at the cathode with the reduced electrolysis surface area so as to remove the impurity ions in the lead electrolyte. The invention can solve the problems of complex process and equipment, high cost, low efficiency, poor impurity removal effect and the like of the traditional electrolyte impurity removal method.

Description

Impurity removal method for lead electrolyte

Technical Field

The invention relates to the technical field of lead electrolysis, in particular to a lead electrolyte impurity removal method.

Background

At present, lead electrolysis is mainly produced by adopting a Bai Ci method (Betts), pure lead is used as a cathode (starting sheet) in the method, crude lead produced by pyrometallurgy is used as an anode, and an electrolyte mainly comprises PbSiF6 (lead hexafluorosilicate dihydrate) and H2SiF6 (fluosilicic acid). During lead electrolysis, metals with higher potential than lead in the anode, such as gold, silver, copper, bismuth, antimony, arsenic and other elements, hardly enter the electrolyte and are left in the anode mud. In actual production, due to the shedding or entrainment of anode mud and the like, a trace amount of the metal enters into the electrolyte, and the concentration of impurity metal in the solution is slowly accumulated along with the production. When the lead content of the anode plate is more than or equal to 97.5 percent, the anode efficiency of the lead is generally higher than the cathode efficiency (the dissolution speed of the lead in the anode is higher than the deposition speed of the cathode), the lead ion concentration in the electrolyte is also increased, and when the lead ion concentration is increased, the conductivity of the electrolyte is deteriorated, and the power consumption is increased.

In the electrolysis production of small polar plates, anode mud on the surface of a residual anode is mainly scrubbed in a mechanical mode, the amount of scrubbing water used in the process of scrubbing the residual anode is small, the concentration of lead and other metal impurities such as bismuth and antimony in the scrubbing water is several times higher than that in an electrolyte, and in the initial stage of high-impurity lead electrolytic refining and lead electrolytic reproduction, when the impurity concentration of the scrubbing water is high, an electrolytic tank is short-circuited or in a special purification tank, a lead plate is filled in the tank, scrubbing water is introduced, and the metal impurities in the scrubbing water are naturally precipitated on the lead plate by lead replacement by utilizing the principle of lead and bismuth replacement.

Several methods for reducing the lead ion concentration of the electrolyte mainly include a precipitation method, an electrolytic deleading method and a cathode replacement periodic method. The precipitation method is mainly to add sulfuric acid into the electrolyte to react lead with sulfuric acid to generate lead sulfate and remove the lead sulfate. The electrolytic deleading method mainly uses insoluble graphite as an anode to perform electrolysis. The replacement cathode cycle method is mainly characterized in that a new cathode is replaced in a long cycle to improve the precipitation speed of lead ions on the cathode, so that the effects of reducing the concentration of the lead ions in the electrolyte, improving the current efficiency and reducing the energy consumption are achieved.

The lead-bismuth displacement method applied to electrolysis of the small polar plate has the advantages of low reaction speed, long purification time, need of adding a pump, a tank and a pipeline, and is not suitable for production of large polar plates. In the electrolysis production of the large polar plate, an automatic unit is adopted to scrub the residual polar, the dosage of washing water is greatly increased, the concentration of impurity metal ions in the washing water is very low, and the concentration of the impurity metal ions in electrolyte is also very low. On one hand, to remove the same metal impurities in the small polar plate, the volume of the electrolyte which is several times of that of the electrolyte electrolyzed by the small polar plate needs to be purified, and the equipment investment is greatly increased. On the other hand, it is difficult to remove impurities from low concentration, the efficiency of removing impurities is greatly reduced, and the cost is also increased.

The precipitation method needs to add equipment and pipelines such as a filter press, a reaction tank and the like, also needs to consume sulfuric acid, and the produced lead sulfate also needs to return to a crude lead smelting system, which is the repeated consumption of energy. The electrolytic deleading method has good effect, but in the actual production, a large number of graphite anodes need to be manufactured, the cost is high, and the graphite electrode method occupies an electrolytic bath, has long deleading time and influences the normal process production. The replacement of the cathode cycle method requires increasing the times of discharging and loading the cell and increasing the workload of cathode manufacture and cathode refining.

The technologies only can remove lead or impurities, and have certain limitations, and in the electrolytic production of lead, a simple and feasible method capable of removing lead and impurities does not exist. Because of the lack of a feasible electrolyte impurity removal method, in order to control the impurity concentration in the electrolyte and obtain the qualified cathode lead, the low-current density (less than or equal to 140A/m < 2 >) production is usually adopted, and the impurity concentration in the electrolyte is controlled within a certain concentration, thereby ensuring that the qualified cathode lead is obtained.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a method for removing impurities from lead electrolyte, so as to solve the problems of complex process and equipment, high cost, low efficiency, poor impurity removal effect, etc. of the conventional method for removing impurities from lead electrolyte.

The invention provides a lead electrolyte impurity removal method, which comprises the following steps:

taking an electrolytic tank with the total amount of less than 2% as an impurity removal electrolytic tank, and taking the rest electrolytic tank as a product electrolytic tank;

carrying out partial insulation covering treatment on the surface of the cathode in the impurity removal electrolytic cell to obtain a cathode with a reduced electrolytic surface area;

placing an anode and the cathode with the reduced electrolysis surface area into the impurity removal electrolytic cell to obtain an impurity removal electrolytic cell to be electrolyzed;

and electrolyzing the impurity removal electrolytic tank to be electrolyzed and the product electrolytic tank in lead electrolyte to separate out impurity ions and lead ions in the lead electrolyte at the cathode with the reduced electrolysis surface area so as to remove the impurity ions in the lead electrolyte.

In addition, the preferable scheme is that the electrode spacing of the impurity removal electrolytic cell to be electrolyzed is twice of the electrode spacing of the product electrolytic cell; wherein the inter-pole distance is a distance between adjacent like poles.

In addition, it is preferable that the cathode for reducing the electrolytic surface area by performing a partial insulation covering treatment on the surface of the cathode in the impurity removal electrolytic cell includes:

and covering the two surfaces of the side edge of the cathode by adopting an insulating material to expose the middle part of the cathode, thereby obtaining the cathode with the reduced electrolytic surface area.

In the cathode having a reduced electrolytic surface area, it is preferable that the area of the portion covered with the insulating material is equal to the area of the exposed portion.

In addition, it is preferable that the insulating material is a soft PVC skin or an insulating strip.

In addition, it is preferable that, after the subjecting the impurity removal electrolytic cell to be electrolyzed and the product electrolytic cell to electrolysis in a lead electrolyte to cause impurity ions and lead ions in the lead electrolyte to be precipitated at the cathode for reducing the electrolysis surface area and remove the impurity ions in the lead electrolyte, the method further includes:

after electrolyzing for a preset period, taking out the cathode with the reduced electrolytic surface area, which is precipitated with impurity ions and lead ions, in the impurity removal electrolytic tank to be electrolyzed, and carrying out insulation covering removal treatment on the cathode with the reduced electrolytic surface area, which is precipitated with the impurity ions and the lead ions, so as to obtain a cathode with the precipitated impurities;

feeding the cathode with the impurities separated out into a fire refining process for impurity removal treatment to obtain lead liquid with the impurities removed;

and (4) casting the lead liquid after impurity removal into a new anode plate.

Further, it is preferable that the impurity ions include: bismuth ions and antimony ions.

According to the technical scheme, the method for removing impurities from the lead electrolyte provided by the invention has the advantages that a small amount (less than 2%) of the electrolytic tank is selected from the total electrolytic tank as the impurity removal electrolytic tank, and partial insulation covering treatment is carried out on the surface of the cathode in the impurity removal electrolytic tank, so that the effective area during cathode electrolysis is reduced, during electrolysis, as the area of the cathode is reduced, the current density of the cathode is increased, the voltage on the surface of the cathode is increased, impurities, such as bismuth, antimony and the like, which cannot be precipitated at the cathode in the electrolyte in normal production (product electrolytic tank) can be precipitated on the surface of the cathode with the reduced electrolysis surface area, and lead can be precipitated on the surface of the cathode in a large amount, so that the purpose of purifying the electrolyte can be achieved. The invention can remove lead ions in the electrolysis of the large polar plate and can also remove the concentration of metal impurity ions in the solution, thereby improving the current density during production, improving the current efficiency and improving the productivity.

To the accomplishment of the foregoing and related ends, one or more aspects of the invention comprise the features hereinafter fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Further, the present invention is intended to include all such aspects and their equivalents.

Drawings

Other objects and results of the present invention will become more apparent and readily appreciated by reference to the following description taken in conjunction with the accompanying drawings, and as the invention becomes more fully understood. In the drawings:

FIG. 1 is a schematic flow chart of a lead electrolyte impurity removal method according to an embodiment of the invention;

FIG. 2 is a schematic of a cathode with reduced electrolytic surface area according to an embodiment of the invention.

In the figure, 1-the cathode reducing the electrolytic surface area, 2-the insulating material covers a portion, 3-the exposed portion of the cathode reducing the electrolytic surface area.

The same reference numbers in all figures indicate similar or corresponding features or functions.

Detailed Description

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details.

Aiming at the problems of complex process and equipment, high cost, low efficiency, poor impurity removal effect and the like of the conventional electrolyte impurity removal method, the lead electrolyte impurity removal method is provided.

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In order to explain the impurity removal method for lead electrolyte provided by the invention, fig. 1 shows the flow of the impurity removal method for lead electrolyte according to the embodiment of the invention.

As shown in fig. 1, the method for removing impurities from lead electrolyte provided by the invention comprises the following steps:

s110, taking an electrolytic tank with the total amount of less than 2% of the electrolytic tank as an impurity removal electrolytic tank, and taking the rest electrolytic tank as a product electrolytic tank;

s120, carrying out partial insulation covering treatment on the surface of the cathode in the impurity removal electrolytic cell to obtain the cathode with the reduced electrolytic surface area;

s130, placing the anode and the cathode with the reduced electrolysis surface area into an impurity removal electrolytic cell to obtain an impurity removal electrolytic cell to be electrolyzed;

and S140, electrolyzing the impurity removal electrolytic tank to be electrolyzed and the product electrolytic tank in the lead electrolyte to separate out impurity ions and lead ions in the lead electrolyte at the cathode with the reduced electrolysis surface area so as to remove the impurity ions in the lead electrolyte.

A small amount (less than 2 percent) of electrolytic tanks are selected from the total electrolytic tanks as impurity removal electrolytic tanks, and partial insulation covering treatment is carried out on the surfaces of cathodes in the impurity removal electrolytic tanks, so that the effective area during cathode electrolysis is reduced, during electrolysis, the current density of the cathodes is increased due to the reduction of the area of the cathodes, the voltage on the surfaces of the cathodes is increased, impurities which cannot be separated out from the cathodes in normal production (product electrolytic tanks), such as bismuth, antimony and the like, can be separated out from the surfaces of the cathodes with the reduced electrolytic surface area, and lead can be separated out from the surfaces of the cathodes in a large amount, so that the aim of purifying the electrolytes can be fulfilled. The invention can remove lead ions in the electrolysis of the large polar plate and can also remove the concentration of metal impurity ions in the solution, thereby improving the current density during production, improving the current efficiency and improving the productivity.

As a preferred scheme of the invention, the inter-polar distance of the impurity removal electrolytic cell to be electrolyzed is twice of the inter-polar distance of the product electrolytic cell; wherein the inter-pole distance is the distance between adjacent homopolars. During electrolysis, the cathode insulating material increases the thickness of the cathode, so that the short circuit is avoided and the electrode spacing of the impurity removal electrolytic cell to be electrolyzed is adjusted to be twice of the electrode spacing of the product electrolytic cell for convenient operation.

FIG. 2 shows a cathode with reduced electrolytic surface area according to an embodiment of the invention;

as shown in FIG. 2, as a preferred embodiment of the present invention, a cathode for reducing the electrolytic surface area obtained by partially covering the surface of the cathode in a depurating electrolytic tank with an insulating coating comprises:

and covering the two surfaces of the side edge of the cathode by using an insulating material to expose the middle part of the cathode, thereby obtaining the cathode 1 with the reduced electrolytic surface area. As shown in fig. 2, the cathode 1 with reduced electrolytic surface area has its both side edges covered with portions 2 of insulating material and its central portion exposed 3. By adopting the method to cover the cathode, impurity ions and lead ions can be separated out in the middle of the cathode under the condition of not influencing electrolysis, thereby facilitating the subsequent impurity removal treatment.

In a preferred embodiment of the present invention, in the cathode having a reduced electrolytic surface area, the area of the portion covered with the insulating material is equal to the area of the exposed portion. The method is convenient to be used as a basis for adjusting the inter-polar distance, and the impurity removal effect is optimal. The insulation area can also be adjusted according to the conditions in production.

In a preferred embodiment of the present invention, the insulating material is a soft PVC skin or an insulating strip. This is the preferred material and other insulating materials may be used instead as long as a reduction in the electrolytic area of the cathode is achieved.

As a preferable scheme of the invention, after the impurity removal electrolytic tank to be electrolyzed and the product electrolytic tank are electrolyzed in the lead electrolyte, so that impurity ions and lead ions in the lead electrolyte are precipitated at a cathode for reducing the electrolysis surface area, and the impurity ions in the lead electrolyte are removed, the method further comprises the following steps:

after a preset period of electrolysis, taking out the cathode with the reduced electrolysis surface area, which is precipitated with impurity ions and lead ions in the impurity removal electrolytic cell to be electrolyzed, and carrying out insulation covering removal treatment on the cathode with the reduced electrolysis surface area, which is precipitated with the impurity ions and the lead ions, to obtain a cathode with the precipitated impurities;

feeding the cathode with the impurities separated out into a fire refining process for impurity removal treatment to obtain lead liquid with the impurities removed;

and (4) casting the lead liquid after impurity removal into a new anode plate.

The impurity removal electrolytic tank is a small part of the electrolytic tank in the lead electrolysis process, and has the function of reducing the electrolysis area of a cathode to separate out metal ions in lead electrolyte on the surface of the electrolytic tank, and the cathode with the impurities separated out can obtain a lead product after further refining, so that the lead product needs to be cast into a new anode again and then used as the anode of the product electrolytic tank to carry out electrolysis to obtain the lead product.

As a preferred embodiment of the present invention, the impurity ions include: bismuth ions and antimony ions. Is a small amount of impurities mixed in the lead electrolyte. Of course other metal ions may be included.

In order to better explain the method for removing impurities from lead electrolyte, specific embodiments are provided below.

Example 1

The components of the processed lead anode plate are Pb98.2%, sb0.6%, bi0.5%, as0.5%, cu0.06% and Ag0.1%. After the electrolysis is carried out for a period of time, the concentrations of lead, antimony, bismuth ions and the like in the electrolyte are respectively increased to 150g/L, 2g/L and 0.05g/L, the increase of the ion concentrations can increase the resistance of the electrolyte, so that the power consumption of the electrolysis is increased, and therefore, the ion concentrations are required to be reduced to be within the normal range (60-120 g/L of lead, 0.8-1.2 g/L of antimony and 0.001-0.003 g/L of bismuth).

Both sides of the 3-slot starting sheet (as shown in FIG. 2) were covered with soft PVC about half the surface area of the cathode plate, and the lower part of the PVC was fixed with plastic buttons as shown in FIG. 2. Then, the cathode plates and half of the anode plates in 6 electrolytic tanks which have been electrolyzed for 5 days are taken out of the tank, and the anode plates are hung one by one when being taken out of the tank, so that the inter-polar distance is adjusted from the original 110mm to 220mm. Then, the starting sheet covered with PVC was hoisted to the 6 electrolytic cells one by one, and electrolysis was carried out by energization.

Because the area of the cathode in the impurity removal electrolytic tank (3 tanks) is reduced by about half, the current density of the cathode is increased to 280A/m ² The current density is the original current density (140A/m) ² ) About twice of that of the cathode, a great amount of lead, bismuth and antimony can be precipitated on the surface of the cathode under the high current density. After electrolysis for 1-2 days, the electrolytic bath is short-circuited, then the cathode and the anode are respectively hoisted to a cathode washing unit and a residual anode washing unit for washing, and after washing, the soft PVC covered on the cathode plate is taken down for reuse. And the washed cathode is not sent to the ingot casting process, but returned to the anode scrap casting pot to be cast into the anode plate again.

The above operation was carried out for 3 of the cells on each working day until the concentrations of lead, bismuth, antimony and the like in the electrolyte were restored to within the normal range.

According to the method for removing impurities from lead electrolyte provided by the invention, a small amount (less than 2%) of the total electrolytic cells are selected as the impurity removal electrolytic cells, and partial insulation covering treatment is carried out on the surface of the cathode in the impurity removal electrolytic cells, so that the effective area during cathode electrolysis is reduced, and during electrolysis, as the area of the cathode is reduced, the current density of the cathode is increased, the voltage on the surface of the cathode is increased, impurities such as bismuth and antimony which cannot be precipitated on the cathode in the electrolyte (product electrolytic cells) during normal production can be precipitated on the surface of the cathode with the reduced electrolysis surface area, and lead can be precipitated on the surface of the cathode in a large amount, so that the purpose of purifying the electrolyte can be achieved. The invention can remove lead ions in the electrolysis of the large polar plate and can also remove the concentration of metal impurity ions in the solution, thereby improving the current density during production, improving the current efficiency and improving the productivity.

The method for removing impurities from lead electrolyte according to the invention is described above by way of example with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that various modifications may be made to the method for removing impurities from lead electrolyte provided by the present invention without departing from the scope of the invention. Therefore, the scope of the present invention should be determined by the contents of the appended claims.

Claims (6)

1. The impurity removal method for the lead electrolyte is characterized by comprising the following steps:

taking an electrolytic tank with the total amount of less than 2% as an impurity removal electrolytic tank, and taking the rest electrolytic tank as a product electrolytic tank;

carrying out partial insulation covering treatment on the surface of the cathode in the impurity removal electrolytic cell to obtain a cathode with a reduced electrolytic surface area;

putting an anode and the cathode with the reduced electrolysis surface area into the impurity removal electrolytic cell to obtain an impurity removal electrolytic cell to be electrolyzed;

electrolyzing the impurity removal electrolytic tank to be electrolyzed and the product electrolytic tank in a lead electrolyte to separate out impurity ions and lead ions in the lead electrolyte at the cathode with the reduced electrolysis surface area so as to remove the impurity ions in the lead electrolyte; wherein the inter-polar distance of the impurity removal electrolytic cell to be electrolyzed is twice of the inter-polar distance of the product electrolytic cell; the pole pitch is the distance between adjacent like poles.

2. The method for removing impurities from lead electrolyte according to claim 1, wherein the step of partially insulating and covering the surface of the cathode in the impurity removal electrolytic cell to obtain the cathode with reduced electrolytic surface area comprises the following steps:

and covering two surfaces of the side edge of the cathode by adopting an insulating material to expose the middle part of the cathode, thereby obtaining the cathode with the reduced electrolysis surface area.

3. The method for removing impurities from lead electrolyte according to claim 2,

in the cathode for reducing the electrolytic surface area, the area of the portion covered with the insulating material is equal to the area of the exposed portion.

4. The impurity removing method for lead electrolyte according to claim 2, wherein the insulating material is soft PVC skin.

5. The method for removing impurities from lead electrolyte according to claim 1, wherein after the electrolysis of the impurity removal electrolytic tank to be electrolyzed and the product electrolytic tank in lead electrolyte, the impurity ions and the lead ions in the lead electrolyte are precipitated at the cathode with reduced electrolysis surface area, and the impurity ions in the lead electrolyte are removed, the method further comprises the following steps:

after electrolyzing for a preset period, taking out the cathode with the reduced electrolytic surface area, which is precipitated with impurity ions and lead ions, in the impurity removal electrolytic tank to be electrolyzed, and carrying out insulation covering removal treatment on the cathode with the reduced electrolytic surface area, which is precipitated with the impurity ions and the lead ions, so as to obtain a cathode with the precipitated impurities;

feeding the cathode with the impurities separated out into a fire refining process for impurity removal treatment to obtain lead liquid with the impurities removed;

and (4) casting the lead liquid after impurity removal into a new anode plate.

6. The impurity removing method for lead electrolyte according to claim 1, wherein the impurity ions comprise: bismuth ions and antimony ions.

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