An acid recovery device

Abstract

The application belongs to the technical field of water treatment, and particularly discloses an acid recovery device. The acid recovery device comprises an acid separator and acid concentration electrodialysis. The acid separator is sequentially arranged and placed by a positive charge microporous semi-permeable membrane, a negative charge fibrous filler, a positive charge microporous semi-permeable membrane, a raw material chamber separation net and a positive charge microporous semi-permeable membrane. The components arranged in this way can be arranged in multiple ways to realize more efficient treatment. Dilute acid from the acid separator enters the acid concentration electrodialysis component for treatment. The acid recovery device has the advantages of fast diffusion speed, high salt concentration of waste acid, the ability to treat waste acid with high salt concentration, high recovery rate and the like.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and specifically relates to an acid recovery device. Technical Background

[0002] In industrial production and mining processes (such as the iron and steel industry, titanium dioxide industry, hydrometallurgical copper industry, titanium material industry, electroplating industry, rare earth industry, wood saccharification industry, gold mining, and non-ferrous metal smelting industry), inorganic acids (such as sulfuric acid, hydrochloric acid, nitric acid, and hydrofluoric acid) are often used to clean metal surfaces or dissolve ores. This generates a large amount of waste acid solutions containing various metal ions. If these solutions are discharged without treatment, they not only waste natural resources but, more seriously, pollute the environment, soil, and water sources. Therefore, taking measures to separate, purify, and recycle these solutions has always been a focus of attention.

[0003] Membrane-based waste acid recovery utilizes the dialysis principle. The entire diffusion dialysis device is composed of diffusion dialysis membranes, a distribution plate, reinforcing plates, and a flow plate frame. A certain number of membranes form different structural units; each unit is separated into dialysis chamber A and diffusion chamber B by an anion exchange membrane. When waste acid and receiving solution (tap water) are introduced to opposite sides of the anion exchange membrane, the concentration of sulfuric acid and its salts on the waste acid side is much higher than on the water side. Therefore, due to the concentration gradient, waste acid and its salts tend to permeate into chamber B. However, the membrane is selectively permeable; it does not allow all ions to pass through with equal opportunity. First, the anion exchange membrane framework itself carries a positive charge, attracting negatively charged hydrated ions in the solution while repelling positively charged hydrated ions. Thus, under the influence of the concentration difference, anions on the waste acid side are attracted and smoothly permeate through the membrane pores into the water side. Simultaneously, based on the requirement of electroneutrality, positively charged ions will also be entrained. Since hydrogen ions have a smaller hydration radius and lower charge, while metal salt ions have a larger hydration radius and higher valence, they preferentially pass through the membrane, thus separating the acid from the waste liquid. Due to the countercurrent operation, although the acid concentration in the acid chamber at the waste liquid outlet is greatly reduced due to diffusion, it is still higher than the acid concentration in the inlet water. Furthermore, in actual membrane fabrication, the water content and pore size can be controlled through side-group substitution. Therefore, diffusion dialysis can generally achieve an acid recovery rate of over 80%.

[0004] Diffusion dialysis technology has been around for over 50 years, but its widespread application has been limited by the limitations of membrane technology. In recent years, however, membrane technology has developed rapidly, with a wide variety of membranes emerging, which has also driven the development of diffusion dialysis technology.

[0005] In China, institutions such as the Shanghai Institute of Organic Chemistry, the University of Science and Technology of China, and the Hangzhou Water Treatment Technology Research and Development Center of the State Oceanic Administration are working on or have already developed ion-exchange anion exchange membranes for acid recovery. Shandong Tianwei Membrane Technology Co., Ltd. has developed a diffusion dialysis unit for acid recovery and possesses a homogeneous membrane production process with independent intellectual property rights. Its product quality has reached international advanced levels. The diffusion dialysis units produced by this company are widely used for the recovery of waste acid from titanium dioxide, steel products, and hydrometallurgical processes, generating significant economic and social benefits.

[0006] Abroad, the technology for recovering acid via diffusion dialysis has developed rapidly, with the United States and Japan being representative examples. Exergy Processes in the United States has developed a new online diffusion dialysis technology and has already implemented it industrially. This process uses ion exchange membranes to treat waste sulfuric acid, enabling its recycling. The system is controlled by flow meters and level gauges and is designed to be fully automated. Positioning grids are installed between the membranes to maintain the stability of the stack. Acid recovery rates can reach 88%, and metal rejection rates reach 95%, significantly reducing the amount of dialysis solution sent to wastewater treatment systems, thereby reducing the consumption of neutralizing chemicals and energy consumption.

[0007] Sawyer and Smith, an American company, has also launched the FORMECO series of acid recovery equipment. Its key feature is the introduction of minute pressure between the baffles, significantly improving the reliability and lifespan of this component. The equipment is compact and requires little floor space; a unit processing 400 L / d occupies only 1.4 m². The equipment is fully automated, capable of continuous 24 / 7 operation without interruption, requiring only periodic cleaning and replacement of the filter media. Acid recovery rates are 85%–90%, and metal retention rates are 60%–90%.

[0008] The above descriptions demonstrate that diffusion dialysis membrane recovery technology has unparalleled advantages over other membrane processes. However, current diffusion dialysis methods for acid recovery share common characteristics: slow diffusion rates, limited salt concentrations in waste acid, and low recovery rates. Based on these limitations, we have specifically developed an acid recovery device with an acid recovery rate of 4 L / m²·h, an acid recovery rate exceeding 95%, a salt ion retention rate exceeding 99.5%, and the ability to recover waste acid with salt concentrations up to 200 g / L. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention develops an acid recovery device. This invention is achieved through the following technical solution:

[0010] An acid recovery device, comprising an acid separator and an acid concentration electrodialysis unit, characterized in that:

[0011] The acid separator is composed of a positively charged microporous semipermeable membrane, a negatively charged fibrous packing, a positively charged microporous semipermeable membrane, a raw material chamber partition, and a positively charged microporous semipermeable membrane arranged in sequence; this arrangement of components can be repeated multiple times to achieve greater processing efficiency.

[0012] The acid separator includes an inlet for saline waste acid, an inlet for pure water, an outlet for residual acid, and an outlet for recovered dilute acid.

[0013] The dilute acid outlet of the acid separator is connected to the inlet of the acid concentration electrodialysis unit. A positively charged microporous membrane is used for initial separation of acid and salt. Then, a negatively charged fibrous adsorbent material adsorbs metal ions from the recovered acid, resulting in highly pure dilute acid. This dilute acid is then concentrated using acid concentration electrodialysis to obtain the recovered acid.

[0014] Preferably, the positively charged microporous membrane of the aforementioned acid recovery device is made from a pure tetrafluoroethylene porous membrane with a thickness of 0.05-0.2 mm and a pore size of 5-20 micrometers as the raw material. It is impregnated with chloropropyl styrene, with 0.1-0.5 g / kg of peroxybenzoic acid as a catalyst, and polymerized at a high temperature of 110-160°C to form a base fabric. The base fabric is then immersed in a 1.0-15% aqueous solution of m-phenylenediamine or o-phenylenediamine for 1-2 hours at a reaction temperature of 80-110°C to form positively charged functional groups. The microporous membrane with the formed positively charged functional groups is then immersed in a 6-15% aqueous solution of tetrapropylamine hydroxide for 2-8 hours. Finally, it is immersed in a 3-5% solution of a mixture of oxalic acid and hydrochloric acid for 10-15 hours.

[0015] Preferably, the anion membrane in the electrodialysis concentration component of the aforementioned acid recovery device is an AZH acid-resistant anion membrane manufactured by Hangzhou Water Treatment Center, and the cation membrane is a CZF acid-resistant cation membrane manufactured by Hangzhou Water Treatment Center. This product is currently available on the open market.

[0016] Preferably, the operating conditions for the electrodialysis concentration component of the aforementioned acid recovery device are: membrane flow velocity of 0.1-0.5 cm / s, operating temperature of 20-40℃, operating voltage of each membrane pair of 0.05-0.1 V, and current density of 600-2000 A / m³. 2 .

[0017] Beneficial effects: The acid recovery device developed in this invention has an acid recovery rate of up to 4L / m2.h, an acid recovery rate of over 95%, a salt ion retention rate of over 99.5%, and can recover waste acid with a salt concentration of up to 200g / L. It features fast diffusion speed, can handle waste acid with even higher salt concentrations, and has a high recovery rate.

[0018] Legend

[0019] Figure 1 Schematic diagram of acid separation component

[0020] 1. Salt-containing waste acid inlet; 2. Pure water inlet; 3. Positively charged microporous semi-permeable membrane; 4. Negatively charged fibrous packing material; 5. Raw material chamber partition; 6. Residual acid outlet; 7. Recovered dilute acid outlet. Detailed Implementation

[0021] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings:

[0022] Example 1

[0023] The process uses a 0.1 mm thick pure tetrafluoroethylene porous membrane as the raw material, with a pore size of 10 micrometers. It is impregnated with chloropropyl styrene, with 0.2 g / kg of peroxybenzoic acid as a catalyst, and polymerized at 130°C to form the base fabric. The base fabric is then immersed in a 5% m-phenylenediamine aqueous solution for 1.5 hours at a reaction temperature of 90°C to form positively charged functional groups. The microporous membrane with the formed positively charged functional groups is first immersed in an 8% tetrapropylammonium hydroxide aqueous solution for 5 hours, followed by washing four times with water. It is then immersed in a 4% solution of a 50% mixture of oxalic acid and hydrochloric acid for 12 hours, followed by washing with water for 1.5 hours, completing the post-treatment.

[0024] The acid separation component is assembled in the following order: positively charged microporous semipermeable membrane 3, negatively charged fibrous packing 4, positively charged microporous semipermeable membrane 3, raw material chamber partition 5, positively charged microporous semipermeable membrane 3... positively charged microporous semipermeable membrane 3, negatively charged fibrous packing 4, positively charged microporous semipermeable membrane 3, raw material chamber partition 5, and positively charged microporous semipermeable membrane 3.

[0025] The acid-resistant anion membrane used in the acid concentration electrodialysis is the AZH anion membrane, a product of Hangzhou Water Treatment Center, and the acid-resistant cation membrane is the CZF cation membrane, a product of Hangzhou Water Treatment Center. 100 pairs of anion and cation membranes with a size of 550*1100mm are stacked together.

[0026] The tested saline waste acid had a sulfuric acid concentration of 80 g / L, a nickel sulfate concentration of 120 g / L, and a sodium sulfate concentration of 150 g / L. The acid separation operation conditions were an influent flow rate of 600 L / h and an influent waste acid flow rate of 100 L / h.

[0027] The operating conditions for acid concentration electrodialysis were set as follows: membrane flow rate of 0.3 cm / s, operating temperature of 30℃, operating voltage of 0.08V per membrane pair, and current density of 1200 A / m². After the above treatment process, the acid recovery rate can reach 95%, the impurity removal rate in the recovered acid can reach 99.5%, and the concentration of recovered sulfuric acid can reach 150 g / L.

[0028] Example 2

[0029] The process uses a 0.15 mm thick pure tetrafluoroethylene porous membrane as the raw material, with a pore size of 5 micrometers. It is impregnated with chloropropyl styrene, with 0.15 g / kg of peroxybenzoic acid as a catalyst, and polymerized at 150°C to form the base fabric. The base fabric is then immersed in an 8% m-phenylenediamine aqueous solution for 2 hours at a reaction temperature of 100°C to form positively charged functional groups. The microporous membrane with the formed positively charged functional groups is first immersed in a 10% tetrapropylammonium hydroxide aqueous solution for 5 hours, followed by 5 washes with water. It is then immersed in a 5% solution of a 50% mixture of oxalic acid and hydrochloric acid for 15 hours, followed by a 2-hour wash with water, completing the post-treatment process.

[0030] The acid separation component is assembled in the following order: positively charged microporous semipermeable membrane 3, negatively charged fibrous packing 4, positively charged microporous semipermeable membrane 3, raw material chamber partition 5, positively charged microporous semipermeable membrane 3... positively charged microporous semipermeable membrane 3, negatively charged fibrous packing 4, positively charged microporous semipermeable membrane 3, raw material chamber partition 5, and positively charged microporous semipermeable membrane 3.

[0031] The acid-resistant anion membrane used in the acid concentration electrodialysis is the AZH anion membrane, a product of Hangzhou Water Treatment Center, and the acid-resistant cation membrane is the CZF cation membrane, a product of Hangzhou Water Treatment Center. 100 pairs of anion and cation membranes with a size of 550*1100mm are stacked together.

[0032] The tested saline waste acid had a sulfuric acid concentration of 50 g / L, a nickel sulfate concentration of 120 g / L, and a sodium sulfate concentration of 100 g / L. The acid separation operation conditions were an influent flow rate of 600 L / h and an influent waste acid flow rate of 100 L / h.

[0033] The operating conditions for acid concentration electrodialysis were set as follows: membrane flow rate of 0.5 cm / s, operating temperature of 30℃, operating voltage of 0.1V per membrane pair, and current density of 1500 A / m². After the above treatment process, the acid recovery rate can reach 96%, the impurity removal rate in the recovered acid can reach 99.6%, and the concentration of recovered sulfuric acid can reach 150 g / L.

[0034] Example 3

[0035] The process uses a 0.1 mm thick pure tetrafluoroethylene porous membrane with a pore size of 5 micrometers as the raw material. It is polymerized using chloropropyl styrene impregnated with 0.1 g / kg peroxybenzoic acid as a catalyst at 150°C to form the base fabric. The base fabric is then immersed in a 10% o-phenylenediamine aqueous solution at 100°C for 1 hour to form positively charged functional groups. The microporous membrane with the formed positively charged functional groups is then immersed in a 15% tetrapropylammonium hydroxide aqueous solution for 3 hours, followed by washing four times with water. Next, it is immersed in a 6% solution of a 50% mixture of oxalic acid and hydrochloric acid for 15 hours, followed by washing with water for 2 hours, completing the post-treatment process.

[0036] The acid separation component is assembled in the following order: positively charged microporous semipermeable membrane 3, negatively charged fibrous packing 4, positively charged microporous semipermeable membrane 3, raw material chamber partition 5, positively charged microporous semipermeable membrane 3... positively charged microporous semipermeable membrane 3, negatively charged fibrous packing 4, positively charged microporous semipermeable membrane 3, raw material chamber partition 5, and positively charged microporous semipermeable membrane 3.

[0037] The acid-resistant anion membrane used in the acid concentration electrodialysis is the AZH anion membrane, a product of Hangzhou Water Treatment Center, and the acid-resistant cation membrane is the CZF cation membrane, a product of Hangzhou Water Treatment Center. 100 pairs of anion and cation membranes with a size of 550*1100mm are stacked together.

[0038] The tested saline waste acid had a sulfuric acid concentration of 80 g / L, a nickel sulfate concentration of 120 g / L, and a sodium sulfate concentration of 150 g / L. The acid separation operation conditions were an influent flow rate of 600 L / h and an influent waste acid flow rate of 100 L / h.

[0039] The operating conditions for acid concentration electrodialysis were set as follows: membrane flow rate of 0.5 cm / s, operating temperature of 35℃, operating voltage of 0.1V per membrane pair, and current density of 1800 A / m². After the above treatment process, the acid recovery rate can reach 95%, the impurity removal rate in the recovered acid can reach 99.5%, and the concentration of recovered sulfuric acid can reach 150 g / L.

Claims

1. An acid recovery device, comprising an acid separator and an acid concentration electrodialysis unit, characterized in that: The acid separator is composed of a positively charged microporous semipermeable membrane (3), a negatively charged fibrous packing (4), a positively charged microporous semipermeable membrane (3), a raw material chamber partition (5), and a positively charged microporous semipermeable membrane (3) arranged in sequence. The positively charged microporous semipermeable membrane (3) is made by using a pure tetrafluoroethylene porous membrane with a thickness of 0.05-0.2 mm and a pore size of 5-20 micrometers as the raw material, impregnated with chloropropyl styrene, and with 0.1-0.5 g / kg of peroxybenzoic acid as the catalyst, and polymerizing at a high temperature of 110-160℃ to form a base fabric; then immersing the base fabric in an aqueous solution of m-phenylenediamine or o-phenylenediamine with a mass concentration of 1.0-15% for 1-2 hours at a reaction temperature of 80-110℃ to form positively charged functional groups; then immersing the microporous membrane with the formed positively charged functional groups in an aqueous solution of tetrapropylamine hydroxide with a mass concentration of 6-15% for 2-8 hours; and finally immersing it in a mixed solution of oxalic acid and hydrochloric acid with a mass concentration of 3-5% for 10-15 hours to obtain the final product. The acid separator includes a salt waste acid inlet (1), a pure water inlet (2), a residual acid outlet (6), and a recovered dilute acid outlet (7); The dilute acid outlet of the acid separator is connected to the inlet of the acid concentration electrodialysis unit.

2. The acid recovery device according to claim 1, characterized in that: The operating conditions for acid concentration electrodialysis are as follows: membrane flow rate of 0.1-0.5 cm / s, operating temperature of 20-40℃, operating voltage per membrane pair of 0.05-0.1 V, and current density of 600-2000 A / m³. 2 .

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