Treatment method of chlorine-containing copper sulfate waste liquid

Abstract

The invention relates to a treatment method of a chlorine-containing copper sulfate waste liquid, which comprises the following steps: feeding and mixing the chlorine-containing copper sulfate waste liquid, a sodium carbonate solution and an ammonium bicarbonate solution at the same time, carrying out a first reaction, and carrying out solid-liquid separation to obtain basic cupric carbonate and a first filtrate; carrying out nanofiltration treatment on the first filtrate to obtain a sodium-ammonium-containing sulfate solution, mixing the sodium-ammonium-containing sulfate solution with tetraphenylborate, and carrying out a second reaction to obtain tetraphenylborate; according to the treatment method, the copper recovery rate is preferably increased to 99.0% or above, the chlorine content in the obtained basic cupric carbonate product is as low as 0.0017 wt% or below, the purity is as high as 97.0% or above, and the bulk density is as low as 0.0036 g / cm < 3 > or below; meanwhile, an ammonium resource in the chlorine-containing copper sulfate waste liquid is converted into an ammonium tetraphenylborate product with the purity preferably reaching 98.7% or above, and comprehensive recycling of valuable resources in the chlorine-containing copper sulfate waste liquid is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of industrial waste liquid treatment, in particular to a method for treating chlorocopper sulfate waste liquid. Background Art

[0002] During the copper sulfate production process, as the copper sulfate crystallization mother liquor is continuously recycled, the chlorine content in the copper sulfate solution continues to increase, which affects the quality of copper sulfate crystals. This is especially true for high-purity copper sulfate, which has higher impurity requirements. In order to stabilize the product market, the copper sulfate solution needs to be replaced from time to time, but it also faces the problems of increased disposal costs and reduced resource recycling rates, and subsequent wastewater disposal is also difficult. Similarly, in the wet copper recycling industry, when chloride ions exceed a certain concentration, not only will the anode plate be easily perforated, reducing its service life, but it will also cause the electrolytic cathode copper to become brittle and not dense enough.

[0003] Currently, methods for removing chloride ions mainly include electrolysis, ion exchange, recrystallization, extraction, and precipitation. For example, CN118183949A discloses a method for selectively removing chloride ions using an electrochemical working unit. This method requires switching the electrode polarity under different working conditions and requires precise control of the electric field direction and the layout of the liquid channel. The operation process is complex and the conditions are harsh. In addition, the choice of electrode materials in this method is relatively limited, and hydrogen or oxygen evolution reactions may occur during the reaction process, which not only reduces the chloride ion removal efficiency but also may cause corrosion to the equipment.

[0004] For example, CN106435206A discloses a method for removing chlorine from a copper sulfate solution using copper refining slag. In this method, the copper refining slag is added to a chlorine-containing copper sulfate solution. The cuprous chloride in the copper refining slag reacts with chloride ions to form cuprous chloride, which is insoluble in acid, to remove the chloride ions. However, this method has limited dechlorination efficiency and also introduces various impurities from the copper refining slag, such as compounds of lead, tin, arsenic, antimony, zinc, nickel, and cobalt. Furthermore, the operation steps are complex, energy consumption is high, and the processing cost is high.

[0005] In view of this, a treatment method for chlorine-containing copper sulfate solution is provided with high dechlorination efficiency, simple process and low energy consumption, which can reduce the treatment cost and comprehensively recycle the valuable components therein. This is a technical problem that needs to be solved in the current field. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a method for treating chlorocopper sulfate waste liquid, which realizes the efficient recovery and utilization of copper in chlorocopper sulfate, avoids the adhesion of chloride ions in the copper product, and simultaneously realizes the separation and purification of chlorine itself and the recovery and utilization of ammonium, converting it into high-value by-products ammonium chloride and tetraphenylammonium borate, thus realizing the comprehensive recovery and utilization of valuable resources in chlorocopper sulfate waste liquid.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for treating chlorocopper sulfate waste liquid, which comprises the following steps:

[0009] (1) simultaneously feeding and mixing chlorinated copper sulfate waste liquid, sodium carbonate solution, and ammonium bicarbonate solution and performing a first reaction, followed by solid-liquid separation to obtain basic copper carbonate and a first filtrate;

[0010] (2) subjecting the first filtrate in step (1) to nanofiltration to obtain a sodium ammonium sulfate solution, and then mixing the sodium ammonium sulfate solution with tetraphenylborate and subjecting the mixture to a second reaction to obtain tetraphenylammonium borate.

[0011] The treatment method of the present invention adopts a sodium carbonate solution as a conversion agent and an ammonium bicarbonate solution as a modification promoter, and selects a feeding method of simultaneous feeding and mixing. Compared with the traditional feeding method, the simultaneous feeding enables the copper in the chloro-copper sulfate waste liquid to be converted more promptly. Combined with the synergistic effect of the sodium carbonate solution and the ammonium bicarbonate solution, the copper ions in the chloro-copper sulfate waste liquid will generate blue copper hydroxide at the moment of contact with the single sodium carbonate solution, and then decompose and convert into black copper oxide when heated. Therefore, when only the single sodium carbonate solution is used for copper ion conversion, the synthesized basic copper carbonate may be mixed with components such as copper hydroxide or copper oxide, thereby affecting the purity and color of the basic copper carbonate. However, under the synergistic effect of the sodium carbonate solution and the ammonium bicarbonate solution, a complex reaction occurs between the copper hydroxide and the ammonium ion, thereby preventing the copper hydroxide from being decomposed by heat. Finally, the copper hydroxide can be smoothly converted into high-quality basic copper carbonate without introducing other copper-containing components. The treatment method efficiently recovers and utilizes the copper in the chlorosulfate-containing waste liquid, avoids the influence of impurity elements in the chlorosulfate-containing waste liquid on the conversion and recovery of copper, and ensures that the obtained basic copper carbonate product has good hydrophobic dispersibility, uniform particle distribution, and low chloride ion adhesion. At the same time, the ammonium resources in the chlorosulfate-containing waste liquid are converted into relatively high-value ammonium tetraphenylborate, thereby realizing the comprehensive recovery and utilization of valuable resources in the chlorosulfate-containing waste liquid. Moreover, the treatment method does not require complex equipment and expensive reagents, has low energy consumption and treatment costs, and is environmentally friendly without generating inferior waste.

[0012] It is worth noting that the ammonium bicarbonate solution in step (1) of the treatment method of the present invention adopts a saturated ammonium bicarbonate solution, that is, the concentration of ammonium bicarbonate in the solution reaches the maximum solubility and no ammonium bicarbonate crystals are precipitated.

[0013] Preferably, the chlorine-containing copper sulfate waste liquid in step (1) comprises 2wt% to 4wt% of copper sulfate, 0.5wt% to 1wt% of hydrochloric acid and 5wt% to 10wt% of sulfuric acid.

[0014] Among them, 2wt% to 4wt% copper sulfate can be, for example, 2wt%, 2.2wt%, 2.5wt%, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt% or 4wt%.

[0015] Preferably, the mass concentration of the sodium carbonate solution in step (1) is 10wt% to 20wt%, for example, it can be 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%.

[0016] Preferably, the simultaneous feeding and mixing in step (1) includes first mixing the sodium carbonate solution and the ammonium bicarbonate solution to obtain a first mixed solution, and then simultaneously feeding and mixing the first mixed solution and the chloro-containing copper sulfate solution.

[0017] Preferably, the volume ratio of the sodium carbonate solution to the ammonium bicarbonate solution in the first mixed solution is 1:(0.1-0.15), for example, it can be 1:0.1, 1:0.11, 1:0.12, 1:0.13, 1:0.14 or 1:0.15.

[0018] The present invention further preferably has a volume ratio of the sodium carbonate solution to the ammonium bicarbonate solution in the first mixed solution of 1:(0.1-0.15). This is beneficial for promoting the complexation of copper ions and ensuring efficient conversion of basic copper carbonate, while also preventing copper residue in the first filtrate. If the volume ratio of the sodium carbonate solution to the ammonium bicarbonate solution is too large, that is, the amount of ammonium bicarbonate solution added is too small, the quality of the basic copper carbonate will be reduced, and the finished product will be mixed with other components (such as copper hydroxide and copper oxide), thereby affecting the purity and appearance color. If the volume ratio of the sodium carbonate solution to the ammonium bicarbonate solution is too small, that is, the amount of ammonium bicarbonate solution added is too large, a large amount of copper ions will remain in the first filtrate, thereby affecting subsequent processing.

[0019] Preferably, the feed rates of the chlorocopper sulfate waste liquid and the first mixed solution are each independently 60 to 90 mL / s, for example, 60 mL / s, 65 mL / s, 70 mL / s, 75 mL / s, 80 mL / s, 85 mL / s or 90 mL / s.

[0020] The present invention further preferably has a feed rate of 60 to 90 mL / s for the chlorocopper sulfate waste liquid and the first mixed solution, each independently being 60 to 90 mL / s, which is beneficial to improving the copper recovery rate and ensuring that the obtained basic copper carbonate product has a uniform particle size distribution and high bulkiness. If the feed rate of the chlorocopper sulfate waste liquid and the first mixed solution is too fast, the two will not be fully mixed, and a local reaction will occur first, ultimately resulting in uneven particle size. If the feed rate of the chlorocopper sulfate waste liquid and the first mixed solution is too slow, the copper conversion efficiency will be reduced.

[0021] Preferably, the first reaction in step (1) includes sequentially performing a first aging and a second aging.

[0022] Preferably, the pH of the first pre-aging mixed system is 7.5 to 8.5, for example, it can be 7.5, 7.6, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4 or 8.5.

[0023] Preferably, the pH of the mixed system after the first aging and before the second aging is 5.0-6.0, for example, it can be 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9 or 6.0.

[0024] The present invention further preferably has a pH of the mixed system after the first aging and before the second aging of 5.0 to 6.0, which is conducive to ensuring that the obtained basic copper carbonate product has a uniform dark green color and high purity. If the pH of the mixed system after the first aging and before the second aging is too low, the basic copper carbonate product will have an uneven color. If the pH of the mixed system after the first aging and before the second aging is too high, by-products such as copper hydroxide will be generated, resulting in a decrease in the purity of the basic copper carbonate.

[0025] Preferably, the first aging time is 20 to 30 minutes, for example, 20 minutes, 22 minutes, 25 minutes, 28 minutes or 30 minutes.

[0026] Preferably, the second aging time is 40 to 60 min, for example, 40 min, 42 min, 45 min, 48 min, 50 min, 52 min, 55 min, 58 min or 60 min.

[0027] Preferably, the temperature of the first reaction in step (1) is 60-70°C, for example, 60°C, 62°C, 65°C, 68°C or 70°C.

[0028] Preferably, step (1) further comprises sequentially performing a first washing and a first drying on the basic copper carbonate.

[0029] Preferably, during the first washing, the mass ratio of the basic copper carbonate to the washing liquid is 1:(1-1.5), for example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0030] Preferably, the first washing comprises a centrifugal wash.

[0031] Preferably, the rotation speed of the centrifugal washing is 15 to 25 r / min, for example, it can be 15 r / min, 18 r / min, 20 r / min, 22 r / min or 25 r / min.

[0032] Preferably, the centrifugal washing time is 20 to 30 minutes, for example, 20 minutes, 22 minutes, 25 minutes, 28 minutes or 30 minutes.

[0033] Preferably, the first drying temperature is 90-105°C, for example, 90°C, 92°C, 95°C, 98°C, 100°C, 102°C or 105°C.

[0034] Preferably, the first drying time is 2 to 3 hours, for example, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours or 3 hours.

[0035] Preferably, the tetraphenylborate in step (2) comprises sodium tetraphenylborate.

[0036] Preferably, the tetraphenyl borate in step (2) and the NH4 + The mass ratio is (0.4-0.8):1, for example, it can be 0.4:1, 0.5:1, 0.6:1, 0.7:1 or 0.8:1.

[0037] The present invention further preferably comprises the tetraphenyl borate in step (2) and the NH4 + The mass ratio of is (0.4-0.8):1, which is conducive to the complete conversion reaction and the complete separation of ammonium sulfate and sodium sulfate in the sodium ammonium sulfate solution, thereby ensuring the purity of the tetraphenylammonium borate product; if the tetraphenylborate and the NH4 + The mass ratio of tetraphenylborate is too low, the amount of sodium tetraphenylborate is insufficient, and ammonium sulfate cannot be separated from the mixed salt solution, which leads to incomplete separation of the components in the sodium ammonium sulfate solution, affecting subsequent treatment; if the tetraphenylborate and the sodium ammonium sulfate solution contain NH4 + The mass ratio of tetraphenylborate to sodium tetraphenylborate is too high, and excessive use of sodium tetraphenylborate will result in residual sodium tetraphenylborate in the generated ammonium tetraphenylborate, thereby affecting the purity of the ammonium tetraphenylborate product.

[0038] Preferably, the temperature of the second reaction in step (2) is 40-60°C, for example, 40°C, 42°C, 45°C, 48°C, 50°C, 52°C, 55°C, 58°C or 60°C.

[0039] Preferably, the time of the second reaction in step (2) is 2 to 3 hours, for example, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours or 3 hours.

[0040] Preferably, step (2) further comprises performing a second washing and a second drying on the tetraphenylammonium borate.

[0041] Preferably, during the second washing, the mass ratio of the tetraphenylammonium borate to the washing liquid is 1:(2-3), for example, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8 or 1:3.

[0042] Preferably, the second washing time is 1 to 2 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours.

[0043] Preferably, the second drying temperature is 90-100°C, for example, 90°C, 92°C, 95°C, 98°C or 100°C.

[0044] Preferably, the second drying time is 3 to 4 hours, for example, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours or 4 hours.

[0045] Preferably, the nanofiltration treatment in step (2) also obtains a sodium ammonium chloride solution.

[0046] Preferably, step (2) further comprises concentrating the sodium-ammonium chloride salt solution, and calcining the obtained sodium-ammonium chloride salt to obtain sodium chloride crystals.

[0047] Preferably, the calcination temperature is 350-450°C, for example, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 450°C.

[0048] The present invention further preferably uses a calcination temperature of 350 to 450° C., which is beneficial for fully releasing NH3 and HCl from the sodium-ammonium chloride salt and improving the purity of the ammonium chloride product. If the calcination temperature is too low, the separation of the sodium-ammonium chloride salt will be incomplete, resulting in a decrease in the purity of the obtained ammonium chloride product. If the calcination temperature is too high, energy consumption will be increased and the color quality of the ammonium chloride product will be affected.

[0049] Preferably, the calcination time is 0.5 to 1 h, for example, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h.

[0050] Preferably, step (2) further comprises dissolving the sodium chloride crystals to obtain a sodium chloride solution, and then mixing the sodium chloride solution with the ammonium bicarbonate solution and performing a third reaction to obtain an ammonium chloride solution.

[0051] It is worth noting that the above sodium chloride solution and the above ammonium bicarbonate solution are both in a saturated state and no crystals are precipitated, that is, they are saturated sodium chloride solution and saturated ammonium bicarbonate solution respectively.

[0052] Preferably, the volume ratio of the sodium chloride solution to the ammonium bicarbonate solution is 1:(1-1.5), for example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0053] Preferably, the temperature of the third reaction is 30-40°C, for example, 30°C, 32°C, 35°C, 38°C or 40°C.

[0054] Preferably, the third reaction time is 1 to 2 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours.

[0055] Preferably, step (2) further comprises sequentially concentrating and drying the ammonium chloride solution (third drying) to obtain ammonium chloride crystals.

[0056] Preferably, the drying temperature is 60-80°C, for example, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 78°C or 80°C.

[0057] Preferably, the drying time is 2 to 3 hours, for example, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours or 3 hours.

[0058] Preferably, the calcination further produces tail gas, and the tail gas comprises NH3 and HCl.

[0059] Preferably, step (2) further comprises absorbing the tail gas in a sulfuric acid solution and a sodium hydroxide solution in sequence, mixing the obtained ammonium sulfate solution into the sodium-ammonium sulfate solution, and using the obtained sodium chloride solution to dissolve the sodium chloride crystals.

[0060] Preferably, the mass concentration of the sulfuric acid solution is 15 wt% to 25 wt%, for example, it can be 15 wt%, 18 wt%, 20 wt%, 22 wt% or 25 wt%.

[0061] Preferably, the mass concentration of the sodium hydroxide solution is 25wt% to 35wt%, for example, it can be 25wt%, 28wt%, 30wt%, 32wt% or 35wt%.

[0062] Preferably, after the third reaction, solid-liquid separation is performed to obtain sodium bicarbonate precipitate and ammonium chloride solution.

[0063] Preferably, step (2) further comprises alkali leaching of the sodium bicarbonate precipitate.

[0064] Preferably, the OH in the alkali solution used in the alkali leaching treatment - The mass concentration of the polyol is 25 wt% to 35 wt%, for example, it can be 25 wt%, 28 wt%, 30 wt%, 32 wt% or 35 wt%.

[0065] Preferably, during the alkali leaching treatment, the mass ratio of the sodium bicarbonate precipitate to the alkali solution is 1:(1.5-2), for example, it can be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.

[0066] Preferably, the alkali leaching treatment time is 1 to 2 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours or 2 hours.

[0067] Preferably, the alkali solution is a sodium hydroxide solution, and the sodium carbonate solution obtained after the alkali leaching treatment is recycled to step (1).

[0068] Preferably, in step (2), after the second reaction, solid-liquid separation is performed to obtain tetraphenylammonium borate and a second filtrate.

[0069] Preferably, step (2) further comprises performing bipolar membrane treatment on the second filtrate to obtain sulfuric acid solution and sodium hydroxide solution.

[0070] The bipolar membrane treatment described in the present invention adopts an anionic and cationic composite membrane. The anode side is composed of an acid chamber composed of a composite membrane and an anionic membrane, the cathode side is composed of an alkali chamber composed of a composite membrane and a cationic membrane, and the middle position is composed of a salt chamber composed of a plurality of anionic membranes and cationic membranes in sequence.

[0071] Preferably, the bipolar membrane treatment is performed in a direct current electric field.

[0072] Preferably, the DC voltage of the DC electric field is 7 to 12 V, for example, it can be 7V, 7.5V, 8V, 8.5V, 9V, 9.5V, 10V, 10.5V, 11V, 11.5V or 12V.

[0073] Preferably, the DC current of the DC electric field is 2-4 A, for example, 2 A, 2.2 A, 2.5 A, 2.8 A, 3 A, 3.2 A, 3.5 A, 3.8 A or 4 A.

[0074] Compared with the prior art, the present invention has at least the following beneficial effects:

[0075] (1) The method for treating chlorosulfate copper waste liquid provided by the present invention utilizes sodium carbonate solution and ammonium bicarbonate solution as conversion agents and modification promoters, and selects a feeding method of simultaneous feeding and mixing to convert and recover copper in the chlorosulfate copper waste liquid, thereby improving the copper recovery rate and reducing the influence of chloride ions on the copper product. Furthermore, by optimizing the ratio of the sodium carbonate solution to the ammonium bicarbonate solution, the feeding rate, the pH value of the mixed system and other process parameters, the chlorine content of the obtained basic copper carbonate product is preferably as low as 0.0017wt% or less, the purity is as high as 97.0% or more, and the particles are evenly dispersed, with a loose density as low as 0.0036g / cm 3 At the same time, tetraphenylborate is used to fully convert the ammonium resources in the chlorocopper sulfate waste liquid, and the purity of the obtained ammonium tetraphenylborate is preferably as high as 98.7wt% or more.

[0076] (2) The present invention provides a method for treating chloro-copper sulfate waste liquid. The method further converts the chloride ions in the first filtrate into products to prepare an ammonium chloride product with a purity preferably above 98.9 wt%. In addition, the method cleverly recycles the intermediate product, forming a closed loop for the entire process without generating secondary waste or secondary wastewater. Moreover, the required treatment conditions are relatively mild, and no complex equipment or expensive reagents are required, thereby further reducing the treatment cost and realizing efficient and comprehensive recovery and utilization of valuable resources in the chloro-copper sulfate waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 is a process flow chart of the treatment method provided in Example 1 of the present invention;

[0078] Figure 2 This is a physical picture of the basic copper carbonate product obtained by the treatment method provided in Example 1 of the present invention;

[0079] Figure 3 This is a physical picture of the ammonium chloride crystal product obtained by the treatment method provided in Example 1 of the present invention;

[0080] Figure 4 This is a physical picture of the tetraphenylammonium borate product obtained by the treatment method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0081] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0082] The treatment method step (1) described in the following examples or comparative examples is carried out in a reaction tank, and 1m3 Tap water is used as the base material, stirring is started and the temperature is raised to 60-70°C (for example, 60°C, 62°C, 65°C, 68°C or 70°C, etc.), and then feeding is started; the first aging is performed after the total amount of feeding (including tap water) is about 80% of the capacity of the reactor; after the second aging, 1m 3 The reaction slurry is used as a base material to continue the first reaction in step (1), and the remaining reaction slurry is used for subsequent operations.

[0083] The bipolar membrane treatment described in the following examples or comparative examples uses a bipolar membrane system JED-600 produced by Zhejiang Blue Pole Membrane Technology Co., Ltd.

[0084] 1. Implementation

[0085] Example 1

[0086] This embodiment provides a method for treating chlorocopper sulfate waste liquid, according to Figure 1 The process flow shown in FIG. 1 is carried out, and the treatment method comprises the following steps:

[0087] (1) Add 1m 3 Tap water is used as the base material, stirring is started and the temperature is raised to 65°C, and then a mixed solution of chlorocopper sulfate waste liquid (including 3wt% copper sulfate, 0.8wt% hydrochloric acid and 8wt% sulfuric acid), sodium carbonate solution (mass concentration is 15wt%) and saturated ammonium bicarbonate solution, i.e., a first mixed solution (volume ratio is 1:0.12) is fed and mixed at a feeding rate of 75mL / s and a first reaction is carried out. During the simultaneous feeding and mixing process, the pH of the mixed system is 8, and the temperature is kept constant. After the total amount of feed (including tap water) is 80% of the reactor capacity, the feeding is suspended and the first aging is carried out for 25min, and the feeding is continued until the pH of the mixed system is 5.6, and the second aging is carried out for 50min; 1m 3 The reaction slurry was used as a base material to continue the above operation, and the remaining reaction slurry was transferred to a scraper centrifuge (rotation speed of 20 r / min) to centrifuge to separate the first precipitate, i.e., basic copper carbonate, and the first filtrate. Subsequently, the basic copper carbonate was washed (centrifugally washed) with water at a mass ratio of 1:1.2 for 25 minutes, and then dried at 100° C. for 2.5 hours to obtain a basic copper carbonate product, and the washing water was added to the first filtrate;

[0088] (2) subjecting the first filtrate of step (1) to nanofiltration to obtain a sodium ammonium sulfate solution and a sodium ammonium chloride solution;

[0089] The sodium ammonium chloride solution is subjected to distillation and centrifugation to obtain sodium ammonium chloride (a mixed salt of ammonium chloride and sodium chloride) and distillate water (used for subsequent washing of the first precipitate and the second precipitate or preparation of the saturated sodium chloride solution); the sodium ammonium chloride is calcined at 400° C. for 0.8 h to obtain tail gas (NH3 and HCl) and calcination residue (sodium chloride crystals); the tail gas is successively subjected to acid absorption and alkali absorption by sulfuric acid solution (mass concentration of 20wt%) and sodium hydroxide solution (mass concentration of 30wt%), respectively, and the obtained ammonium sulfate solution is mixed with the sodium ammonium sulfate solution to obtain chloride. A sodium chloride solution is used to dissolve the sodium chloride crystals to obtain a saturated sodium chloride solution; the saturated sodium chloride solution is then mixed with the saturated ammonium bicarbonate solution at a volume ratio of 1:1.3 and subjected to a third reaction at 35°C for 1.5 hours, followed by filtration to obtain a sodium bicarbonate precipitate and an ammonium chloride solution; the ammonium chloride solution is subjected to a third drying at 70°C for 2.5 hours after distillation and centrifugation to obtain an ammonium chloride product; the sodium bicarbonate precipitate is then mixed with a sodium hydroxide solution (mass concentration of 30 wt%) at a mass ratio of 1:1.8 and subjected to an alkali leaching treatment for 1.5 hours to obtain a sodium carbonate solution, which is recycled to step (1);

[0090] The sodium tetraphenylborate and the NH4 + The sodium ammonium sulfate solution and sodium tetraphenylborate are mixed in a mass ratio of 0.6:1, and a second reaction is carried out at 50°C for 3 hours, and a second precipitate, i.e., ammonium tetraphenylborate, is obtained by filtration. The ammonium tetraphenylborate is pulped and washed for 1.5 hours at a mass ratio of ammonium tetraphenylborate to water of 1:2.5, filtered, and dried for a second time at 95°C for 3.5 hours to obtain an ammonium tetraphenylborate product, and the washing water is incorporated into the second filtrate. The second filtrate is then subjected to bipolar membrane treatment, and under a DC electric field, the DC voltage is adjusted to 10V and the DC current is adjusted to 3A to obtain a sodium hydroxide solution and a sulfuric acid solution, which are recycled to the absorption process of the tail gas obtained by calcining the sodium ammonium chloride salt.

[0091] like Figure 2 As shown, the basic copper carbonate product obtained in this embodiment is a dark green powder. Figure 3 As shown, the ammonium chloride product obtained in this embodiment is white crystalline particles (98 mesh), and the particles are evenly dispersed; Figure 4 As shown, the tetraphenylammonium borate product obtained in this example is white crystalline particles with uniform particle size.

[0092] Example 2

[0093] This embodiment provides a method for treating chlorocopper sulfate waste liquid, which comprises the following steps:

[0094] (1) Add 1m 3Tap water is used as the base material, stirring is started and the temperature is raised to 60°C, and then a mixed solution of chlorocopper sulfate waste liquid (including 2wt% copper sulfate, 0.5wt% hydrochloric acid and 5wt% sulfuric acid), sodium carbonate solution (mass concentration is 10wt%) and saturated ammonium bicarbonate solution (volume ratio is 1:0.1) is fed and mixed at a feeding rate of 60mL / s and a first reaction is carried out. During the simultaneous feeding and mixing process, the pH of the mixed system is 7.5, and the temperature is kept constant. After the total amount of feed (including tap water) is 75% of the reactor capacity, the feeding is suspended and the first aging is carried out for 20min, and the feeding is continued until the pH of the mixed system is 5.0 and then the second aging is carried out for 40min; 1m 3 The reaction slurry is used as a base material to continue the above operation, and the remaining reaction slurry is transferred to a scraper centrifuge (rotation speed of 15r / min) to centrifugally separate the first precipitate, i.e., basic copper carbonate, and the first filtrate. Subsequently, the basic copper carbonate is subjected to a first washing (centrifugal washing) for 20 minutes with water at a mass ratio of 1:1, and then a first drying at 90°C for 3 hours to obtain a basic copper carbonate product, and the washing water enters the first filtrate;

[0095] (2) subjecting the first filtrate of step (1) to nanofiltration to obtain a sodium ammonium sulfate solution and a sodium ammonium chloride solution;

[0096] The sodium-ammonium chloride solution is subjected to distillation and centrifugation to obtain sodium-ammonium chloride (a mixed salt of ammonium chloride and sodium chloride) and distilled water (used for subsequent washing of the first precipitate and the second precipitate or preparation of the saturated sodium chloride solution); the sodium-ammonium chloride is calcined at 350° C. for 1 hour to obtain tail gas (NH3 and HCl) and calcination residue (sodium chloride crystals); the tail gas is sequentially treated with sulfuric acid solution (mass concentration of 15wt%) and sodium hydroxide solution (mass concentration of 25wt%), and the obtained ammonium sulfate solution is mixed with the sodium-ammonium sulfate solution to obtain chloride The sodium solution is used to dissolve the sodium chloride crystals to obtain a saturated sodium chloride solution; the saturated sodium chloride solution is then mixed with the saturated ammonium bicarbonate solution at a volume ratio of 1:1 and subjected to a third reaction at 40°C for 1 hour, followed by filtration to obtain a sodium bicarbonate precipitate and an ammonium chloride solution; the ammonium chloride solution is subjected to distillation and centrifugation and then dried at 60°C for a third time for 3 hours to obtain an ammonium chloride product; the sodium bicarbonate precipitate is then mixed with a sodium hydroxide solution (mass concentration of 25 wt%) at a mass ratio of 1:1.5 and subjected to an alkali leaching treatment for 2 hours to obtain a sodium carbonate solution, which is recycled to step (1);

[0097] The sodium tetraphenylborate and the NH4 +The sodium ammonium sulfate solution and sodium tetraphenylborate are mixed in a mass ratio of 0.4:1, and a second reaction is carried out at 40°C for 3 hours, and a second precipitate, i.e., ammonium tetraphenylborate, is obtained by filtration. The ammonium tetraphenylborate is pulped and washed for 2 hours at a mass ratio of ammonium tetraphenylborate to water of 1:2, filtered, and dried for a second time at 90°C for 4 hours to obtain an ammonium tetraphenylborate product, and the washing water is incorporated into the second filtrate. The second filtrate is then subjected to bipolar membrane treatment, and under a DC electric field, the DC voltage is adjusted to 7V and the DC current is adjusted to 2A to obtain a sodium hydroxide solution and a sulfuric acid solution, which are recycled to the absorption process of the tail gas obtained by calcining the sodium ammonium chloride salt.

[0098] The basic copper carbonate product obtained in this example is a dark green powder, the ammonium chloride product obtained is white crystalline particles (90 mesh), and the particles are evenly dispersed. The tetraphenylammonium borate product obtained is white crystalline particles with uniform particle size.

[0099] Example 3

[0100] This embodiment provides a method for treating chlorocopper sulfate waste liquid, which comprises the following steps:

[0101] (1) Add 1m 3 Tap water is used as the base material, stirring is started and the temperature is raised to 70°C, and then a mixed solution of chlorocopper sulfate waste liquid (including 4wt% copper sulfate, 1wt% hydrochloric acid and 10wt% sulfuric acid), sodium carbonate solution (mass concentration is 20wt%) and saturated ammonium bicarbonate solution (volume ratio is 1:0.15) is fed and mixed at a feeding rate of 90mL / s and a first reaction is carried out. During the simultaneous feeding and mixing process, the pH of the mixed system is 8.5, and the temperature is kept constant. After the total amount of feed (including tap water) is 85% of the reactor capacity, the feeding is suspended and the first aging is carried out for 30min, and the feeding is continued until the pH of the mixed system is 6.0 and then the second aging is carried out for 60min; 1m 3 The reaction slurry is used as a base material to continue the above operation, and the remaining reaction slurry is transferred to a scraper centrifuge (rotation speed is 25r / min) to centrifugally separate the first precipitate, i.e., basic copper carbonate, and the first filtrate. Subsequently, the basic copper carbonate is subjected to a first washing (centrifugal washing) for 30 minutes with water at a mass ratio of 1:1.5, and then a first drying at 105°C for 2 hours to obtain a basic copper carbonate product, and the washing water enters the first filtrate;

[0102] (2) subjecting the first filtrate of step (1) to nanofiltration to obtain a sodium ammonium sulfate solution and a sodium ammonium chloride solution;

[0103] The sodium ammonium chloride solution is subjected to distillation and centrifugation to obtain sodium ammonium chloride (a mixed salt of ammonium chloride and sodium chloride) and distilled water (used for subsequent washing of the first precipitate and the second precipitate or preparation of the saturated sodium chloride solution); the sodium ammonium chloride is calcined at 450° C. for 0.5 h to obtain tail gas (NH3 and HCl) and calcination residue (sodium chloride crystals); the tail gas is sequentially treated with sulfuric acid solution (mass concentration of 25wt%) and sodium hydroxide solution (mass concentration of 35wt%), and the obtained ammonium sulfate solution is mixed with the sodium ammonium sulfate solution to obtain chloride A sodium chloride solution is used to dissolve the sodium chloride crystals to obtain a saturated sodium chloride solution; the saturated sodium chloride solution is then mixed with the saturated ammonium bicarbonate solution at a volume ratio of 1:1.5 and subjected to a third reaction at 30°C for 2 hours, followed by filtration to obtain a sodium bicarbonate precipitate and an ammonium chloride solution; the ammonium chloride solution is subjected to distillation and centrifugation and then dried at 80°C for a third time for 2 hours to obtain an ammonium chloride product; the sodium bicarbonate precipitate is then mixed with a sodium hydroxide solution (mass concentration of 35 wt%) at a mass ratio of 1:2 and subjected to an alkali leaching treatment for 1 hour to obtain a sodium carbonate solution, which is recycled to step (1);

[0104] The sodium tetraphenylborate and the NH4 + The sodium ammonium sulfate solution and sodium tetraphenylborate are mixed in a mass ratio of 0.8:1, and a second reaction is carried out at 60°C for 2h, and a second precipitate, i.e., ammonium tetraphenylborate, is obtained by filtration. The ammonium tetraphenylborate is pulped and washed for 1h at a mass ratio of ammonium tetraphenylborate to water of 1:3, filtered, and dried for a second time at 100°C for 3h to obtain an ammonium tetraphenylborate product, and the washing water is incorporated into the second filtrate. The second filtrate is then subjected to bipolar membrane treatment, and under a DC electric field, the DC voltage is adjusted to 12V and the DC current is adjusted to 4A to obtain a sodium hydroxide solution and a sulfuric acid solution, which are recycled to the absorption process of the tail gas obtained by calcining the sodium ammonium chloride salt.

[0105] The basic copper carbonate product obtained in this example is a dark green powder, the ammonium chloride product obtained is white crystalline particles (100 mesh), and the particles are evenly dispersed. The tetraphenylammonium borate product obtained is white crystalline particles with uniform particle size.

[0106] Example 4

[0107] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1, except that the volume ratio of the sodium carbonate solution to the saturated ammonium bicarbonate solution in step (1) is 1:0.08.

[0108] Example 5

[0109] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1, except that the volume ratio of the sodium carbonate solution to the saturated ammonium bicarbonate solution in step (1) is 1:0.16.

[0110] Example 6

[0111] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1 except that the feed rate in step (1) is 55 mL / s.

[0112] Example 7

[0113] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1 except that the feed rate in step (1) is 95 mL / s.

[0114] Example 8

[0115] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1 except that step (1) continues to add materials until the pH of the mixed system reaches 6.2.

[0116] Example 9

[0117] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1 except that step (1) continues to add materials until the pH of the mixed system reaches 4.8.

[0118] Example 10

[0119] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1 except that the calcination temperature in step (2) is 470°C.

[0120] Example 11

[0121] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that of Example 1 except that the calcination temperature in step (2) is 320°C.

[0122] Example 12

[0123] This embodiment provides a method for treating chlorocopper sulfate waste liquid, wherein the sodium tetraphenylborate and the NH4 + Except that the mass ratio of is 1:1, the rest are the same as in Example 1.

[0124] Example 13

[0125] This embodiment provides a method for treating chlorocopper sulfate waste liquid, wherein the sodium tetraphenylborate and the NH4 + Except that the mass ratio of is 0.3:1, the rest are the same as in Example 1.

[0126] Example 14

[0127] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that in Example 1 except that the volume ratio of the saturated sodium chloride solution to the saturated ammonium bicarbonate solution in step (2) is 1:1.8.

[0128] Example 15

[0129] This embodiment provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as that in Example 1 except that the volume ratio of the saturated sodium chloride solution to the saturated ammonium bicarbonate solution in step (2) is 1:0.6.

[0130] 2. Comparative Example

[0131] Comparative Example 1

[0132] This comparative example provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as Example 1 except that in step (1), the chlorocopper sulfate waste liquid is added to a mixed solution of the sodium carbonate solution and the saturated ammonium bicarbonate solution instead of feeding the materials simultaneously.

[0133] Comparative Example 2

[0134] This comparative example provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as Example 1 except that in step (1), no saturated ammonium bicarbonate solution is added, and only the chlorocopper sulfate waste liquid and the sodium carbonate solution are fed and mixed simultaneously.

[0135] Comparative Example 3

[0136] This comparative example provides a method for treating chlorocopper sulfate waste liquid. The treatment method is the same as Example 1 except that step (2) the sodium ammonium sulfate solution is cooled and crystallized (end point temperature 40° C.).

[0137] 3. Test and its results

[0138] The Cl content, purity, and bulk density of the basic copper carbonate product obtained by the method provided in the above embodiments or comparative examples, as well as the purity of the obtained ammonium chloride product and the obtained tetraphenylammonium borate product were tested, and the Cu recovery rate of the method described in each of the above embodiments or comparative examples was calculated. The results are shown in Table 1;

[0139] Table 1

[0140]

[0141]

[0142] In Table 1, “-” indicates that there are no relevant data;

[0143] The test results show that:

[0144] (1) It can be seen from Examples 1 to 3 that the method for treating chloro-copper sulfate waste liquid provided by the present invention effectively solves the problem in the prior art of low chloride ion removal rate and low purity of copper products caused by the attachment of a large amount of chloride ions to the copper products, thereby achieving efficient recovery and utilization of copper in chloro-copper sulfate waste liquid, with a copper recovery rate of more than 99.0%, and preparing a high-quality basic copper carbonate product with a chlorine content as low as 0.0017 wt %, a purity of more than 97.0%, and a bulk density as low as 0.036 g / cm 3 The method comprises the following steps: simultaneously preparing an ammonium chloride product with a purity of more than 98.9% and an ammonium tetraphenylborate product with a purity of more than 98.7%, thereby fully utilizing valuable resources in chlorinated copper sulfate waste liquid.

[0145] (2) It can be seen from Examples 1 and 4 to 9 that the present invention further improves the recovery and utilization of copper in the chlorocopper sulfate waste liquid by further preferably setting the volume ratio of the sodium carbonate solution to the saturated ammonium bicarbonate solution in step (1) to 1:(0.1-0.15), further preferably setting the feed rates of the chlorocopper sulfate waste liquid and the first mixed solution in step (1) to be 60-90 mL / s, and further preferably setting the pH of the mixed system after the first aging and before the second aging to be 5.0-6.0, thereby further improving the recovery and utilization of copper in the chlorocopper sulfate waste liquid and further improving the quality of the obtained basic copper carbonate.

[0146] (3) It can be seen from Example 1, Example 10 and Example 11 that the calcination temperature in step (2) of Example 10 is relatively high. Although it has no obvious effect on the product quality, the high temperature will increase energy consumption and increase the processing cost; the calcination temperature in step (2) of Example 11 is relatively low, which will make it difficult to completely separate the sodium-containing ammonium chloride salt, affect the subsequent preparation of saturated sodium chloride solution, and further affect the conversion of the third reaction. The ammonium chloride product will still be mixed with sodium salts, resulting in low purity. This shows that the present invention further preferably sets the calcination temperature to 350-450°C, which further improves the purity of the ammonium chloride product.

[0147] (4) It can be seen from Examples 1, 12 and 13 that the sodium tetraphenylborate in step (2) of Example 12 and the NH4 +The mass ratio of tetraphenylborate is too high, and excessive use of sodium tetraphenylborate will result in residual sodium tetraphenylborate in the generated ammonium tetraphenylborate, which in turn leads to low purity of the ammonium tetraphenylborate product; the sodium tetraphenylborate and the NH4 + The mass ratio of tetraphenylborate is too low, and the amount of sodium tetraphenylborate is insufficient, which will lead to the inability to separate ammonium sulfate from the mixed salt solution, resulting in incomplete separation of the components in the sodium ammonium sulfate solution, and reducing the purity of the tetraphenylborate ammonium product; This shows that the present invention further prefers the sodium tetraphenylborate and the NH4 + The mass ratio is (0.4-0.8):1, which further improves the quality of tetraphenylammonium borate products.

[0148] (5) It can be seen from Example 1, Example 14 and Example 15 that the volume ratio of the saturated sodium chloride solution to the saturated ammonium bicarbonate solution in step (2) of Example 14 is too high. When excessive ammonium bicarbonate is used, residual ammonium salt will still be mixed in the ammonium chloride product, resulting in low purity of the ammonium chloride product; the volume ratio of the sodium chloride solution to the saturated ammonium bicarbonate solution in Example 15 is too low, and the amount of ammonium bicarbonate is insufficient, which will result in the inability to completely convert saturated sodium chloride, thereby causing sodium salt to be mixed in the ammonium chloride product and resulting in low purity of the ammonium chloride product; this shows that the present invention further preferably has a volume ratio of saturated sodium chloride solution to the saturated ammonium bicarbonate solution of 1:(1-1.5), which further improves the quality of the ammonium chloride product.

[0149] (6) It can be seen from Example 1 and Comparative Examples 1 to 3 that, since step (1) in Comparative Example 1 is not fed simultaneously, but the chlorinated copper sulfate waste liquid is added to the mixed solution of the sodium carbonate solution and the saturated ammonium bicarbonate solution, the recovery rate of copper decreases and the quality of the obtained basic copper carbonate product decreases; since saturated ammonium bicarbonate solution is not added in step (1) in Comparative Example 2, the looseness of the obtained basic copper carbonate product decreases, and the particle size and color are uneven; since sodium ammonium sulfate solution is cooled and crystallized to obtain sodium sulfate and ammonium sulfate products in Comparative Example 3, the separation effect is poor and the product purity is low; thus, it is shown that the present invention converts the copper in the chlorinated copper sulfate waste liquid by using sodium carbonate solution and ammonium bicarbonate solution and selecting the method of simultaneous feeding and mixing, thereby effectively avoiding the adhesion of chloride ions and preparing a high-quality basic copper carbonate product. At the same time, tetraphenylborate is used to fully convert ammonium ions in the filtrate into a more valuable ammonium tetraphenylborate product, thereby achieving efficient recovery and utilization of valuable resources in the chlorinated waste liquid.

[0150] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for treating chlorocopper sulfate waste liquid, characterized in that: The processing method comprises the following steps: (1) simultaneously feeding and mixing chlorinated copper sulfate waste liquid, sodium carbonate solution, and ammonium bicarbonate solution and performing a first reaction, followed by solid-liquid separation to obtain basic copper carbonate and a first filtrate; (2) subjecting the first filtrate in step (1) to nanofiltration to obtain a sodium ammonium sulfate solution, and then mixing the sodium ammonium sulfate solution with tetraphenylborate and subjecting the mixture to a second reaction to obtain tetraphenylammonium borate.

2. The processing method according to claim 1, characterized in that The chlorinated copper sulfate waste liquid in step (1) comprises 2wt% to 4wt% of copper sulfate, 0.5wt% to 1wt% of hydrochloric acid, and 5wt% to 10wt% of sulfuric acid; Preferably, the mass concentration of the sodium carbonate solution in step (1) is 10wt% to 20wt%.

3. The processing method according to claim 1 or 2, characterized in that The simultaneous feeding and mixing in step (1) comprises first mixing the sodium carbonate solution and the ammonium bicarbonate solution to obtain a first mixed solution, and then simultaneously feeding and mixing the first mixed solution and the chloro-containing copper sulfate solution; Preferably, the volume ratio of the sodium carbonate solution to the ammonium bicarbonate solution in the first mixed solution is 1:(0.1-0.15); Preferably, the feed rates of the chlorocopper sulfate waste liquid and the first mixed solution are independently 60 to 90 mL / s.

4. The processing method according to any one of claims 1 to 3, characterized in that: The first reaction in step (1) includes sequentially performing a first aging and a second aging; Preferably, the pH of the mixed system before the first aging is 7.5 to 8.5; Preferably, the pH of the mixed system after the first aging and before the second aging is 5.0-6.0; Preferably, the first aging time is 20 to 30 minutes; Preferably, the second aging time is 40 to 60 minutes; Preferably, the temperature of the first reaction in step (1) is 60-70°C.

5. The processing method according to any one of claims 1 to 4, characterized in that: The tetraphenylborate in step (2) includes sodium tetraphenylborate; Preferably, the tetraphenyl borate in step (2) and the NH4 + The mass ratio is (0.4-0.8):1; Preferably, the temperature of the second reaction in step (2) is 40-60°C; Preferably, the time of the second reaction in step (2) is 2 to 3 hours.

6. The processing method according to any one of claims 1 to 5, characterized in that: The nanofiltration treatment in step (2) also obtains a sodium ammonium chloride solution; Preferably, step (2) further comprises concentrating the sodium-ammonium chloride salt solution, and calcining the obtained sodium-ammonium chloride salt to obtain sodium chloride crystals; Preferably, the calcination temperature is 350-450°C; Preferably, the calcination time is 0.5 to 1 hour.

7. The processing method according to claim 6, characterized in that Step (2) further comprises dissolving the sodium chloride crystals to obtain a sodium chloride solution, and then mixing the sodium chloride solution with the ammonium bicarbonate solution and performing a third reaction to obtain an ammonium chloride solution; Preferably, the volume ratio of the sodium chloride solution to the ammonium bicarbonate solution is 1:(1-1.5); Preferably, the temperature of the third reaction is 30-40°C; Preferably, the third reaction time is 1 to 2 hours; Preferably, step (2) further comprises concentrating and drying the ammonium chloride solution in sequence to obtain ammonium chloride crystals; Preferably, the drying temperature is 60-80°C; Preferably, the drying time is 2 to 3 hours.

8. The processing method according to claim 6 or 7, characterized in that: The calcination also produces tail gas, and the tail gas includes NH3 and HCl; Preferably, step (2) further comprises absorbing the tail gas in a sulfuric acid solution and a sodium hydroxide solution in sequence, mixing the obtained ammonium sulfate solution into the sodium-ammonium sulfate solution, and using the obtained sodium chloride solution to dissolve the sodium chloride crystals; Preferably, the mass concentration of the sulfuric acid solution is 15wt% to 25wt%; Preferably, the mass concentration of the sodium hydroxide solution is 25wt% to 35wt%.

9. The processing method according to claim 7, characterized in that: After the third reaction, solid-liquid separation is performed to obtain sodium bicarbonate precipitate and ammonium chloride solution; Preferably, step (2) further comprises alkali leaching the sodium bicarbonate precipitate; Preferably, the OH in the alkali solution used in the alkali leaching treatment - The mass concentration is 25wt% to 35wt%; Preferably, during the alkali leaching treatment, the mass ratio of the sodium bicarbonate precipitate to the alkali solution is 1:(1.5-2); Preferably, the alkali leaching treatment time is 1 to 2 hours; Preferably, the alkali solution is a sodium hydroxide solution, and the sodium carbonate solution obtained after the alkali leaching treatment is recycled to step (1).

10. The processing method according to any one of claims 1 to 9, characterized in that: Step (2) After the second reaction, solid-liquid separation is performed to obtain tetraphenylammonium borate and a second filtrate; Preferably, step (2) further comprises performing bipolar membrane treatment on the second filtrate to obtain a sulfuric acid solution and a sodium hydroxide solution; Preferably, the bipolar membrane treatment is carried out in a DC electric field; Preferably, the DC voltage of the DC electric field is 7 to 12 V; Preferably, the DC current of the DC electric field is 2-4A.

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