CN115976577A - Method for improving purification efficiency of electrolyte - Google Patents

Abstract

The invention discloses a method for improving the purification efficiency of electrolyte, and belongs to the technical field of copper electrolytic refining. The method includes five processes: a, copper removal process, b, copper sulfate process, c, primary arsenic removal process, d, nickel sulfate process, e, secondary arsenic removal process. The method is used to improve the removal efficiency of impurities in the electrolyte, increase the arsenic content in the arsenic slag, reduce the energy consumption and cost of cleaning and removing impurities, and can realize the output of nickel sulfate products when the concentration of nickel in the electrolyte is low. In the process of purifying electrolytic waste liquid, this method only produces A-grade copper and does not produce black copper plates. At the same time, after evaporation and concentration of copper sulfate and nickel sulfate, the concentration of arsenic in the de-arsenic replenishment liquid can be significantly increased, and the arsenic concentration in the de-arsenic replenishment liquid can be effectively improved. Arsenic efficiency, increase arsenic content in arsenic slag, reduce energy consumption and cost of arsenic removal.

Description

A method for improving the efficiency of electrolyte purification

technical field

The invention relates to a method for improving the purification efficiency of electrolyte, belonging to the technical field of electrolytic refining.

Background technique

During the electrolytic production process, part of the impurities in the anode plate enters the electrolyte, and a part enters the anode slime. As the electrolytic production progresses, the composition of the electrolyte changes continuously, copper ions are continuously enriched, the acid concentration is continuously reduced, and the impurity elements are constantly changing. Accumulation, in order to ensure the normal progress of electrolytic production and the quality of cathode copper products, it is necessary to purify the electrolyte so that the composition of the electrolyte meets the process requirements.

Elements that are more electronegative than copper, such as zinc, iron, nickel, etc., dissolve from the anode plate to form metal cations that enter the electrolyte, increasing the density of the electrolyte, increasing the resistance of the electrolyte, increasing power consumption, and also affecting the sedimentation of anode slime. Among them, nickel, as a valuable metal element, is generally extracted from the electrolyte by means of evaporation concentration, freezing crystallization, and solid-liquid separation. Crude nickel sulfate (NiSO ₄ 7H ₂ O) The premise of nickel sulfate is that the nickel concentration in the electrolyte reaches about 15g/L, otherwise the production efficiency is low and the product quality is difficult to meet the requirements.

Arsenic, antimony, and bismuth, which are similar in electronegativity to copper, enter the electrolyte not only to increase the density of the electrolyte, but also to easily form floating anode slime to make the cathode plate grow particles. If the content in the cathode copper is too high, it will also affect the cathode copper. Some physical properties, so arsenic, antimony, and bismuth are the most harmful elements. Especially arsenic, because of its high content in the anode plate, accumulates rapidly in the electrolyte and can reach a high concentration. Generally, when the arsenic concentration in the electrolyte reaches 10g/L or more, the purification system must be turned on. Arsenic is removed intermittently to ensure the stability of the electrolytic production system. At present, the most commonly used methods for arsenic removal are as follows:

1. Traditional stepped electrodeposition arsenic removal method

The Chinese Patent Application Announcement No. CN104694978B published on March 23, 2018, "A waste electrolysis treatment method and treatment device", discloses a common electrowinning arsenic removal method in the field of copper electrolysis. It flows through three or more cascade electrolytic cells in sequence, and the concentration of copper ions in the electrolyte decreases continuously. A-grade copper is produced in the first cascade tank, black copper plates are produced in the second cascade electrolyte tank, and the copper concentration in the third cascade electrolyte is reduced below 7g/L to produce black copper powder. The black copper plate produced in the second step needs to be returned to the smelting furnace for re-smelting, which increases the cost of impurity removal and the overall cost of copper smelting. Secondly, in order not to produce black copper sludge in the second step and not to precipitate copper in the third step, strict Controlling the copper concentration in each cascade electrowinning tank is cumbersome to operate. This method requires a lot of equipment, a large amount of labor, and the arsenic removal efficiency is average.

2. Parallel cycle electrowinning arsenic removal

The Chinese Patent Application Announcement No. CN1560289 published on January 5, 2005, "parallel cycle continuous electrowinning arsenic removal method", discloses a commonly used electrowinning arsenic removal method in the field of copper electrolysis. In this method, the liquid in the arsenic removal tank They are all connected in parallel and come from the arsenic removal circulation tank. In order to ensure the precipitation of arsenic, the copper concentration in the arsenic removal circulation tank must be controlled below 7g/L, and the rehydration of the arsenic removal circulation tank uses the solution after copper removal, and the copper ion in the solution after decopper removal The concentration is about 30g/L, so a large amount of de-arsenic solution needs to be returned to the de-arsenic circulation tank for remixing. This method is simple to operate, easy to control the process, and does not produce intermediate materials such as black copper plates. However, because a large amount of back liquid is used to mix the circulating liquid, the arsenic concentration in the circulating liquid is low, the arsenic removal effect is poor, and the arsenic element content in the arsenic slag is low. This method has a simple process and is easy to operate, but the arsenic removal efficiency is relatively low. It is worse than the stepwise electrowinning arsenic removal method.

Step-type electrodeposition arsenic removal uses more electrolytic cells, and the black copper plate produced needs to be returned to the furnace for resmelting, which increases the cost of smelting and is not economical; the parallel cycle electrodeposition arsenic removal method is easy to operate and the process parameters are easier to control. The arsenic solution is mixed with the circulating fluid, resulting in a decrease in the concentration of arsenic in the circulating fluid, poor arsenic removal effect and low efficiency.

The purification and impurity removal of the electrolyte is mainly to remove arsenic and nickel from the electrolyte. In order to solve the defects of the above-mentioned impurity removal method and further improve the purification efficiency of the electrolyte, the present invention provides an electrolyte purification method, which only produces A grade Copper does not produce black copper plates. At the same time, the evaporated and concentrated copper sulfate and nickel sulfate solution can significantly increase the arsenic concentration of the arsenic removal supplement solution, effectively improve the arsenic removal efficiency, and greatly reduce the cost of arsenic removal.

Contents of the invention

The invention provides a method for improving the purification efficiency of the electrolyte. The invention adopts a two-concentration and three-electrodeposition method to purify the electrolyte. This method only produces A-grade copper and other valuable products, and does not produce black The copper plate can effectively improve the effect of parallel cycle electrowinning arsenic removal, the process configuration is reasonable, the operation is simple, the equipment investment cost is low, the arsenic content in the arsenic slag can be increased, the energy consumption and cost of arsenic removal can be significantly reduced, and low nickel concentration in the electrolyte can be achieved When the nickel sulfate product is produced.

The technical solution adopted by the present invention to solve the technical problem is: a method for improving the purification efficiency of the electrolyte, extracting the waste electrolyte of the electrolyte system, removing a part of copper ions by electrowinning, reducing the copper concentration in the electrolyte, and Produce A-grade copper; send the above-mentioned electrodeposited decopper solution to the copper sulfate process, and produce copper sulfate products through vacuum evaporation, water-cooled crystallization, and centrifugation. The liquid is evaporated and concentrated through the copper sulfate process, and the concentration of arsenic in the filtered liquid rises sharply; arsenic removal is carried out by using the parallel cycle continuous electrowinning arsenic removal method, using the insoluble lead anode as the anode, using the electrolytic residual anode as the cathode, and using copper sulfate to filter The back liquid is supplemented as a circulating liquid, and the arsenic in the electrolyte is removed by the parallel cycle electrowinning method; the liquid after arsenic removal is sent to the nickel sulfate system, and the nickel sulfate product is produced through evaporation concentration, water cooling crystallization, and centrifugal separation, and the nickel sulfate is filtered The latter liquid is sent to the secondary arsenic removal process as a circulating liquid replenishment liquid; the parallel cycle electrowinning arsenic removal method is used for secondary arsenic removal, and the liquid filtered by nickel sulfate is used as a circulating liquid replenishment liquid, and the liquid after the second arsenic removal is returned to the electrolytic production system. In order to maintain the volume balance of the electrolyte, it is necessary to add water lost by evaporation and concentration to the electrolyte.

Further, in order to ensure that the copper produced by electrowinning decopper meets the A-grade copper standard, low current density and high flow rate are used for production, and the concentration of liquid copper after decoppering should be kept not lower than 30g/L. Here, the preferred current density is 200A/L m ² , the electrolyte flow rate is 50L/bath·min, and 10 electrowinning copper removal tanks are used for copper removal. At the same time, in order to improve the precipitation density of electrodeposited copper, a small amount of additive bone glue and thiourea should be added. The ratio of the two additions can be adjusted according to the copper precipitation situation. Here, it is preferable to add bone glue 20g/t (Cu) and thiourea 30g/t ( Cu).

Further, in order to ensure that the output of copper sulfate meets the standard of non-agricultural secondary products, the evaporation concentration density must reach more than 1.37g/cm ³ , the end point temperature of cooling and crystallization should be controlled at 20-25°C, and a centrifuge should be used for solid-liquid separation.

Further, 6 electrolytic cells are used for arsenic removal once. In order to ensure the first-time arsenic removal effect, the concentration of the circulating solution for parallel cycle electrowinning arsenic removal should be lower than 6g/L. In order to achieve the effect of increasing the arsenic content in the arsenic slag, a high circulation flow rate is used. Here, the electrolyte flow rate is preferably 60L/bath·min.

Further, in order to ensure that the quality of the crude nickel sulfate produced reaches the first grade, the final density of nickel sulfate evaporation should be controlled at 1.38~1.40g/cm ³ , and the final temperature of frozen crystallization should be controlled at -17~-20°C.

Further, three electrolytic cells are used for primary arsenic removal, and the electrolyte flow rate of 60L/cell min is also used for secondary arsenic removal, so as to increase the amount of liquid supplemented after nickel sulfate high in arsenic, and return the liquid after secondary arsenic removal Electrolysis production system.

Further, in order to ensure that the removal rate of copper in the electrolyte system meets the requirements and achieve the balance of copper ion concentration, the production load or output of copper removal, arsenic removal and copper sulfate can be adjusted. In order to maintain the volume balance of the electrolyte, it is also necessary to add copper sulfate and nickel sulfate to the electrolyte, which is lost by evaporation and concentration.

The beneficial effects of the present invention are:

①Integrating the existing impurity removal process, through the reasonable combination of copper removal, arsenic removal, copper sulfate, nickel sulfate and other processes, the efficiency of electrolyte purification and impurity removal has been improved. This method is simple to operate, easy to control the process, and low investment cost Low;

② No black copper plates are produced during the cleaning process, only A-grade copper and other valuable products are produced;

③Through two times of concentration, the concentration of arsenic in the replenishment solution for electrowinning arsenic removal can be increased, the efficiency of electrowinning arsenic removal can be improved, the arsenic content in arsenic slag can be increased, the efficiency of arsenic removal can be improved, and the energy consumption and cost of arsenic removal can be significantly reduced;

④Because the copper sulfate process is used to concentrate the electrolyte before the production of nickel sulfate, nickel sulfate products can be produced when the nickel concentration in the electrolysis system is lower than 15g/L, realizing the production of nickel sulfate with low nickel concentration and making electrolysis The nickel ion concentration in the system is maintained at a low level.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is a schematic diagram of the traditional stepwise electrodeposition arsenic removal method.

Fig. 2 is a schematic diagram of parallel cycle electrowinning arsenic removal method.

Fig. 3 is the process flow chart of the whole purification system of the present invention.

Fig. 4 is a process flow diagram of the present invention.

In the figure: a, copper removal process, b, copper sulfate process, c, primary arsenic removal process, d, nickel sulfate process, e, secondary arsenic removal process.

Detailed ways

Taking a smelter with an annual output of 150,000 tons of cathode copper, the total volume of the electrolytic circulation system is 4000m ³ , the concentration of copper in the electrolyte is 45g/L, the concentration of arsenic is 10g/L, and the concentration of nickel is 10g/L as an example to illustrate the implementation . At this time, the nickel concentration is low, the effect of direct production of crude nickel sulfate is poor, and the arsenic concentration is also at a relatively low level. The traditional arsenic removal method will affect the arsenic removal efficiency, and the arsenic grade in the produced arsenic slag is low. However, with the method provided by the present invention, the efficiency of arsenic removal can be effectively improved, and a nickel sulfate product can be produced, specifically implemented according to the following steps:

a. As shown in the flow chart of electrowinning copper removal process in Figure 3, ^200m3 of waste electrolyte is extracted from the electrolytic system every day and sent to the copper removal process, and 10 electrowinning cells are used for copper removal, and the current density is 200A/ ^m2 Control, the flow rate is controlled at 50L/(tank·min), and bone glue 20g/t(Cu) and thiourea 30g/t(Cu) are added. Then about 3.1 tons of A-grade copper can be produced per day, and A-grade copper is put into storage and sold as a product. The concentration of liquid copper after electrowinning copper removal is 31g/L. The acid mist generated in the copper removal tank is purified by the acid mist purification tower and then emptied.

b. As shown in the copper sulfate process flow chart in Figure 3, the electrodeposited copper sulfate solution is sent to the copper sulfate process, and the copper sulfate pentahydrate product is produced by vacuum evaporation, water-cooled crystallization, and centrifugation, and the filtered solution 96m ^3. The copper concentration is 31g/L, the arsenic concentration is 21g/L, and the nickel concentration is 19g/L.

c. As shown in the one-time arsenic removal process flow chart in Figure 3, the liquid filtered by copper sulfate is used as the circulating mother liquor replenishment liquid, and the parallel cycle electrowinning arsenic removal mode is adopted, and six electrolytic cells are used for one-time arsenic removal, and the current density is 250A /m ² , the flow rate is controlled at 60L/(tank·min), and the supplementary amount of circulating fluid is supplemented at 3m ³ /h. About 5.5 tons of arsenic slag can be produced per day, with arsenic content of 44% and copper content of 51%. After the arsenic removal, the copper concentration in the liquid is 1.2g/L, the arsenic concentration is 6.8g/L, and the nickel concentration is 19g/L. The volume of the primary arsenic removal system is balanced, and the flow rate of the liquid after the primary arsenic removal to the liquid tank before the evaporation of nickel sulfate is the same as that of the circulating liquid, which is also 3m ³ /h. The acid mist and harmful gas generated in the arsenic removal tank are purified by the acid mist purification tower and then emptied.

d. Send the dearsenic solution to the nickel sulfate process, produce crude nickel sulfate product through evaporation, freeze crystallization, and centrifugation, and obtain 51m ³ of the filtered nickel sulfate solution, and the copper concentration in the filtered solution is 3.1g/L , with arsenic concentration of 12.5g/L and nickel concentration of 11g/L.

e. The nickel sulfate filtered solution is sent to the second arsenic removal process, using 3 electrolytic cells for the second arsenic removal, the current density is 250A/m ² , the flow rate is 60L/(tank·min), and the amount of circulating fluid is replenished Fill in at 1.5m ³ /h. About 1 ton of arsenic slag can be produced per day, with arsenic content of 37% and copper content of 61%. After de-arsenic solution, the concentration of copper is 0.8g/L, the concentration of arsenic is 5.8g/L, and the concentration of nickel is 6.4g/L. The volume of the secondary arsenic removal system is balanced, and the flow rate of the liquid after the second arsenic removal to the liquid tank before nickel sulfate evaporation is the same as that of the circulating liquid, which is also 1.5m ³ /h. The acid mist and harmful gases generated in the arsenic removal tank are purified by the acid mist purification tower and then emptied.

f. The arsenic slag produced by the primary electrowinning and secondary electrowinning arsenic removal is returned to the smelting furnace, and after the second arsenic removal, it is hydraulically filtered and returned to the electrolytic circulation system, and the water lost by evaporation is replenished to the electrolytic circulation system. In particular, when the production of the electrowinning copper removal process is started, the production of subsequent processes can be started at the same time as the liquid after decopper removal is obtained. As long as conditions are met, the production of each process can be carried out at the same time.

Table 1 shows the production data of the traditional arsenic and nickel removal methods. The process flow is as follows: extract 200m ³ electrolytic waste liquid, and remove the arsenic in the electrolyte through the first stage of copper removal, the second stage of copper removal, and the removal of arsenic in sequence. The liquid after arsenic removal is sent to the process of nickel sulfate to remove nickel. It can be seen that for every 200m ³ electrolytic waste liquid, 2.1 tons of arsenic slag and 6.1 tons of crude nickel sulfate can be produced. The amount of metal to remove arsenic is 0.75t, and the total cost of the entire arsenic removal process is 40,800 yuan, so the cost of arsenic removal per ton is 54,000 yuan/t, and 4.9 tons of black copper plates are produced during the production process, and the black copper plates are returned to the furnace for smelting and recycling. Additional charges will apply.

Table 2 is the production data of the impurity removal process of the present invention. As can be seen, it can be seen that every 200 ^m3 electrolytic waste liquid can be processed, 6.4 tons of arsenic slag, 5.4 tons of crude nickel sulfate and 12.2 tons of copper sulfate pentahydrate can be produced. The arsenic grade in the arsenic and arsenic slag is 44%, the arsenic grade in the secondary arsenic removal slag is 37%, the total amount of arsenic removed is 2.75t, and the total cost of the entire arsenic removal process is 111,000 yuan. The cost is 41,000 yuan/t, no black copper plate will be produced during the production process, and crude nickel sulfate products can be produced when the initial nickel concentration of waste liquid is 10g/L.

It can be seen from the above comparison that the electrolyte purification and impurity removal method of the present invention, compared with the traditional method, is simple in operation, easy in process control, high in arsenic removal efficiency, significantly increases the arsenic content in arsenic slag, and lowers the cost of arsenic removal than the traditional method 25%, no black copper plate will be produced in the production process during the de-doping process, only valuable products will be produced, and nickel sulfate products will be produced at a lower nickel concentration.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and description are only the principles and basic operation methods of the present invention. Technical parameters and control conditions can be changed and improved, and these changes and improvements all fall within the scope of the claimed invention.

Claims (7)

1. A method for improving electrolyte purification efficiency, characterized in that: the method may further comprise the steps: a. Extract the waste liquid from the electrolysis system, the copper concentration is 40~60g/L, send the waste liquid to the decopper circulation tank in the decopper process, use the stainless steel plate as the cathode, and use the insoluble lead anode as the anode, and output at the cathode Electrodeposition of copper, the solution after decoppering is used as the production stock solution of the copper sulfate process; b. Pour the liquid after electrowinning copper removal in the copper removal process into the liquid tank before copper sulfate evaporation, and produce copper sulfate products through vacuum evaporation, water cooling crystallization and centrifugation in the copper sulfate process, and the filtrate after centrifugation is used as a primary decopper Circulating fluid supplement for arsenic process; c. Use the insoluble lead anode as the anode, use the electrolytic residual anode as the cathode, and use the parallel cycle electrowinning method to remove arsenic. The liquid in the electrolytic cell is in a parallel state, and the circulating liquid is replenished after filtering with copper sulfate. Arsenic slag is produced on the electrolytic butt anode, and the solution after arsenic removal is used as the raw solution for the nickel sulfate process; d. Pour the liquid after arsenic removal by electrowinning into the liquid tank before the nickel sulfate evaporation, and produce nickel sulfate products through the evaporation concentration, freezing crystallization and centrifugation of the nickel sulfate process. The separated concentrated filtrate is used as a circulating replenishment liquid for the secondary arsenic removal process; e. Use the liquid filtered by nickel sulfate as the circulating replenishment liquid to carry out the secondary electrowinning dearsenization, adopt the parallel cycle electrowinning dearsenic method to carry out the secondary dearsenic, the liquid returns to the electrolytic production system after dearsenic, the primary dearsenic and the secondary dearsenic Arsenic slag from arsenic removal is returned to the smelting furnace. 2. A method for improving the purification efficiency of the electrolyte according to claim 1, characterized in that: in the step a, the current density is 200A/m ² , and the flow rate of the electrolyte is 50L/bath·min, which can ensure that after decopper The copper ion concentration of the solution should not be lower than 30g/L. 3. a kind of method improving electrolyte purification efficiency according to claim 1 is characterized in that: add additive bone glue 20～30g/t (Cu) in the described step a, thiourea 30～40g/t (Cu ). 4. A method for improving the purification efficiency of electrolyte according to claim 1, characterized in that in step b, wherein the end point specific gravity of evaporation and concentration is 1.37~1.40g/cm ³ , and the end point temperature of water-cooled crystallization is controlled at 20 ~25°C. 5. A method for improving the purification efficiency of the electrolyte according to claim 1, characterized in that: in the step c, in order to ensure the effect of removing arsenic, the replenishment flow of the liquid after the copper sulfate is filtered should be controlled so that the de-arsenic The concentration of copper in the electrolyte in the arsenic circulation tank will not be higher than 6g/L. High circulation flow rate is used for electrowinning arsenic removal. The electrolyte flow rate is 60L/tank min. At the same time, the supplementary flow rate of copper sulfate filtrate and the liquid after arsenic removal are discharged into nickel sulfate for evaporation. The flow rate of the front liquid tank is equal to realize the volume balance of the primary arsenic removal system. 6. A method for improving the efficiency of electrolyte purification according to claim 1, characterized in that in step d, wherein the density of nickel sulfate at the end point of vacuum evaporation is controlled at 1.38~1.40g/cm ² , and the end point of freezing crystallization The temperature is controlled at -15~-20°C. 7. A method for improving the efficiency of electrolyte purification according to claim 1, characterized in that: in step e, the technical requirements for secondary arsenic removal are the same as those for primary arsenic removal, and the electrolyte flow rate is 60 L/ tank min, the replenishment flow rate of nickel sulfate filtrate should be equal to the flow rate of liquid return electrolysis system after arsenic removal, so as to realize the volume balance of the secondary arsenic removal system.

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