CN114988520B - A process for efficiently recovering acids and salts using modified special resins - Google Patents

Abstract

The invention discloses a process for efficiently recycling acid and salt by utilizing modified special resin, which comprises the following steps: s1: loading the salt-containing waste acid into a low-bed adsorption column from bottom to top, and collecting effluent liquid at the upper end of the low-bed adsorption column; s2: when the effluent in the step S1 contains acid, introducing water into a low-bed adsorption column from top to bottom for eluting, and collecting the effluent at the lower end; wherein the low-bed adsorption column is a low-bed adsorption column containing modified special resin; wherein the modified special resin is an amphoteric polymer resin taking styrene-divinylbenzene or acrylic acid as a main structure. Wherein, the pH value of the salt-containing liquid obtained by separation and recovery is more than 4, the recovery rate of the obtained acid is more than 99.5 percent, and the concentration c/c0 is more than 0.8, and the salt-containing liquid can be directly returned to a pickling tank for use. The invention realizes the high-efficiency recovery of the acid in the waste liquid, has good separation effect and long service life of the resin, can meet the requirement of industrial stable production, and can be popularized and applied on a large scale.

Description

A process for efficiently recovering acids and salts using modified special resins

Technical field

The invention belongs to the fields of wastewater treatment and chemical industry, and relates to a process for efficiently recovering acids and salts using modified special resin.

Background technique

With the rapid development of my country's economy, the market demand for steel, aluminum alloy and other profiles is increasing. Enterprises such as steel, metallurgy and electroplating often use large amounts of inorganic strong acids to clean or surface polish raw materials or equipment. At present, the treatment of high-concentration acid waste liquid containing heavy metals generated and discharged in the metal surface treatment, electroplating and chemical industries is one of the difficult problems in the field of environmental protection. Usually alkali neutralization or charcoal neutralization is used. The former can recycle heavy metals, but the processing cost exceeds the recycling value; the latter is low-cost, but heavy metals are difficult to recycle, and it brings a lot of sludge. If these waste acids can be effectively recycled and used to produce useful chemical products, it will not only reduce environmental pollution, but also reduce the waste of resources. Therefore, it is necessary to conduct research on the recycling and treatment of waste acids.

The waste acid in my country's enterprises is mainly divided into three categories according to its source: regeneration waste liquid of ion exchange resin, waste pickling liquid in the steel industry and waste acid in the metallurgical electroplating industry. Common waste acid treatment methods include neutralization, diffusion dialysis, spray roasting and acid blocking. Among them, the neutralization method produces a large amount of sludge, pollutes the environment, and wastes acid and metal resources in the wastewater; the diffusion dialysis method has high requirements for membrane quality, slow acid recovery rate, and the yield can only reach 80 to 90%. 10-20% of the acid is mixed into the salt, which requires additional treatment and cannot fundamentally solve the problem of waste acid; the spray roasting method has high energy consumption, large equipment investment, complex process, and high operation and management costs; the acid blocking method is currently the The most economical and effective way to deal with waste acid, but there are still problems such as media, equipment and technology. Domestic reported processes for separating acids and salts using acid-blocking low-bed technology all use strong alkaline anion resins. This type of resin has a serious problem of excessive acid retention. After the equipment has been running for a period of time, acid accumulates layer by layer on the resin, and the acid concentration in the collected salt solution increases, resulting in poor separation of acid and salt. The salt solution also contains acid and needs to be processed again, which cannot fundamentally solve the problem. Therefore, it cannot meet the requirements of stable industrial production and cannot be promoted and applied on a large scale. The purpose of processing waste liquids generated by steel, aluminum and other industries is to recycle waste acid into resources, reduce environmental pollution, reduce resource waste, and achieve a circular economy.

Contents of the invention

Purpose of the invention: The technical problem to be solved by this invention is to provide a process for efficiently recovering acids and salts using modified special resin in view of the shortcomings of the existing technology.

In order to solve the above technical problems, the present invention discloses a process for efficiently recovering acids and salts using modified special resin, which includes the following steps:

S1: Load the salt-containing waste acid into the low-bed adsorption column from bottom to top, and collect the effluent from the upper end of the low-bed adsorption column; the residual elution water is collected first. When the salt content in the effluent is When it is 0~1g/L, start collecting the deacidified salt-containing liquid;

S2: When the effluent in step S1 contains acid, pass water from top to bottom into the low-bed adsorption column for elution, and collect the lower effluent; the residual salt-containing waste acid is collected first. When the effluent contains When the salt content begins to decrease, the desalted acid-containing liquid begins to be collected.

In some embodiments, the salt content in the salt-containing waste acid is 2-30g/L; in some embodiments, the salt content in the salt-containing waste acid is 7-25g/L; in some embodiments, The salt content in the salt-containing waste acid is 12-20g/L.

In some embodiments, the acidity of the salt-containing waste acid is 190-260g/L; in some embodiments, the acidity of the salt-containing waste acid is 200-250g/L; in some embodiments, the The acidity of the salt-containing waste acid is 210-240g/L; in some embodiments, the acidity of the salt-containing waste acid is 220-230g/L; the acidity is measured in H ⁺ .

In some embodiments, the low-bed adsorption column is a low-bed adsorption column containing modified special resin.

In some embodiments, the modified special resin is an amphoteric polymeric resin with styrene-divinylbenzene or acrylic acid as its main structure; in some embodiments, the modified special resin is an amphoteric polymer with styrene-divinyl benzene or acrylic acid as its main structure. It is an amphoteric snake cage resin with benzene as the main structure.

In some embodiments, the amphoteric polymer resin includes a strong base and strong acid polymer resin, a strong base and a weak acid polymer resin, a strong acid and a weak base polymer resin, and a weak acid and weak base polymer resin; in some embodiments, the amphoteric polymer resin It is a strong base and strong acid polymer resin and/or a strong base and weak acid polymer resin.

In some embodiments, the weak base group includes: methylamine, dimethylamine, ethylamine, diethylamine, etc.; in some embodiments, the strong base group includes: Type I quaternary ammonium salt, II type quaternary ammonium salt; in some embodiments, the weak acid group includes: maleic acid, acetic acid, phosphoric acid, etc.; in some embodiments, the strong acid group includes: benzenesulfonic acid, alkylbenzene Sulfonic acid, etc.

In some embodiments, the degree of cross-linking is 2-10%.

The matrix of the modified special resin in the present invention is hydrophobic styrene-divinylbenzene. Through the combination of the above groups, the resin becomes hydrophilic, and at the same time, the acidity and alkalinity of the resin are also adjusted.

In some embodiments, the particle size of the amphoteric polymeric resin is 0.05-0.3mm, the moisture content is 40%-80%, and the wet true density is 1.05-1.10g/cm ³ ; in some embodiments, the amphoteric polymer resin The particle size of the polymer resin is 0.01 to 0.3 mm.

The influence of resin particle size on separation: The resin particle size is relatively small and the specific surface area is larger, which greatly improves the exchange kinetics. The contact adsorption is more complete during acid blocking, and the acid and salt separation effect is better.

In some embodiments, the height of the low-bed adsorption column is 0.1-3.0 m, and the diameter is 0.1-3.0 m.

In some embodiments, before first use, the low-bed adsorption column is filled with modified special resin, 10% NaCl is injected in countercurrent and soaked for 3 hours. After the resin shrinks, new resin is added and soaked until the resin is fully replenished, and then the separator is sealed. Inject pure water into the resin column to flush the resin column. The purpose is to wash away the salt on the resin and allow the resin to expand and the entire bed to be in a compacted state. During the process of flushing with pure water, pay attention to the fact that there cannot be any air in the resin bed and empty it. Moisture in the resin bed.

The process of the present invention can break through the limitation of the height of the resin column, and the resin filling height can generally reach 1 to 2 m, or even as high as 3 m, so it can be applied to the maximum processing capacity of a single set of equipment and improves the exchange dynamics of substances.

In some embodiments, in step S1, the loading amount of the salt-containing waste acid is 1 to 5 BV.

In some embodiments, in step S1, the sample loading rate is 1 to 10 BV/h.

In some embodiments, in step S2, the amount of water used is 1 to 5 BV.

In some embodiments, in step S2, the elution rate is 1 to 10 BV/h.

The process of the present invention is different according to the feed liquid and process requirements. In some embodiments, during the adsorption process, the collection amount of the residual washing water is 0.1~2.5BV, and the collection amount of the deacidification salt-containing liquid is 0.2~2.5BV. 1.5BV; in some embodiments, during the elution process, the collection amount of the residual salt-containing waste acid is 0.1-2.5BV, and the collection amount of the desalted acid-containing liquid is 0.2-1.5BV. By adjusting the volume of each solution section, the processing capacity and separation effect can be adjusted and optimized.

In some embodiments, in step S1, the salt-containing waste acid is a salt-containing waste acid stock solution and/or residual salt-containing waste acid.

In some embodiments, in step S2, the water is newly injected water and/or residual elution water.

In some embodiments, the process for efficiently recovering acids and salts using modified special resin is a multi-cycle adsorption-elution process, which includes the following steps:

S1 first cycle adsorption: clean the acid adsorption resin column, load the salt-containing waste acid into the low-bed adsorption column from bottom to top, and collect the collected effluent from the upper end of the low-bed adsorption column; what is collected first is the residual elution Water, when the salt content in the effluent is 0~1g/L, start collecting the deacidified salt-containing solution, and stop feeding the liquid when the upper end outlet reaches the volume requirement (1~5BV);

S2 first cycle elution: When the effluent in step S1 contains acid, water is passed from top to bottom into the low-bed adsorption column for elution, and the lower end effluent is collected; the residual salt-containing waste acid is collected first. When the salt content in the effluent begins to decrease, start collecting the desalted acid-containing liquid, and stop water inflow (1~5BV) when the lower end liquid reaches the volume requirement;

S3 second cycle adsorption: Load the residual salt-containing waste acid and/or the salt-containing waste acid stock solution obtained in the previous cycle into the low-bed adsorption column from bottom to top, and collect the collected effluent from the upper end of the low-bed adsorption column; The first thing to collect is the residual elution water. When the salt content in the effluent is 0~1g/L, start collecting the deacidified salt-containing solution. Stop feeding the liquid when the upper outlet liquid reaches the volume requirement (1~5BV);

S4 second cycle elution: When the effluent in step S3 contains acid, use the eluting water and/or residual eluting water to flow from top to bottom into the low-bed adsorption column for elution, and collect the lower end effluent; What is collected first is the residual salt-containing waste acid. When the salt content in the effluent begins to decrease, the desalted acid-containing liquid begins to be collected. When the lower end liquid reaches the volume requirement, the water inlet is stopped (1~5BV);

S5: According to the adsorption-elution process of the second cycle mentioned above, repeat adsorption-elution multiple times until the salt-containing waste acid is treated.

The process of the present invention mainly involves passing the salt-containing waste acid through a modified special resin column so that the acid is adsorbed to obtain a deacidified salt-containing liquid. The resin column is eluted with elution water to obtain a desalted acid-containing liquid. The desalted acid-containing liquid can be returned to the system for reuse, improving the effective utilization of market resources.

In the process of the present invention, two processes of adsorption and elution are carried out through a modified special resin column, and the two processes are carried out in an alternate cycle.

Among them, during the adsorption process, the inlet liquid is from the bottom to the top. First, the residual salt-containing waste acid from the previous cycle is introduced from the lower port of the column. After all the input is completed, the salt-containing waste acid stock solution is then added until the outlet liquid reaches the volume. Stop feeding liquid (1~5BV) after request; in the first cycle, all the salt-containing waste acid raw solution will be fed.

Among them, during the adsorption process, while the liquid is being fed, a quantitative amount of residual elution water and deacidification salt-containing liquid are collected sequentially from the upper port; among them, the residual elution water is returned to the next elution cycle for use, and the deacidification salt-containing liquid is the product Enter the subsequent process.

Among them, during the elution process, the inlet liquid is from the top to the bottom. First, the residual elution water from the previous cycle is introduced from the upper port of the column. After all of it is fed in, the original elution and dehydration solution is added until the outlet liquid reaches the volume requirement and stops. Water (1~5BV) is fed in; in the first cycle, everything is washed and dehydrated.

Among them, during the elution process, at the same time as the liquid is being fed, quantitative residual salt-containing waste acid liquid and desalted acid-containing liquid are collected sequentially from the lower port; among them, the residual salt-containing waste acid liquid is returned to the next cycle of adsorption process for use, and the desalted acid-containing liquid is Enter the subsequent process for the product.

Through the process of the present invention, the pH of the deacidified salt-containing liquid obtained by separation and recovery is >4; the acid recovery rate in the desalted acid-containing liquid obtained is >99.5%, and the acid concentration c/c0>0.9, which can be directly returned to the pickling tank for use. .

The process of the present invention is not only applicable to the separation of inorganic strong acid and corresponding metal ions in electrode foil aluminum waste acid, metallurgical wastewater, divorce wastewater, steel pickling wastewater and electroplating wastewater, but also can be applied to the separation system of sugar and acid.

The separator and low-bed adsorption column mentioned in the present invention are both low-bed devices.

The invention has the advantages of good separation effect, long resin service life and wide applicability, can meet the requirements of stable production in industry, and can be promoted and applied on a large scale. At the same time, the present invention truly realizes the resource recycling of industrial waste acid, ensures long-term stable production of enterprises, protects the ecological balance of the environment, and effectively solves the problem of poor separation effect of acid and salt, low concentration of recycled acid, unstable equipment operation, and inability to produce stably for a long time. The problem.

Beneficial effects: Compared with the existing technology, the main innovation points of the present invention are:

(1) Using modified special resin, the acid only enters the resin pores but is not retained. Therefore, it is easy to elute with water. The recovery rate of the acid in the desalted acid-containing liquid obtained by the present invention is high, reaching more than 99.5%. At the same time, , the removal rate of metal ions in the desalted acid-containing liquid can also reach more than 99.5%, and the recovered acid concentration c/c ₀ >0.9 can be directly returned to the production line for use; and the pH of the collected deacidified salt-containing liquid is >4 , the separation effect is significantly better than that of traditional strong alkaline anion exchange resin. At the same time, by controlling the process parameters, the separation effect can be further optimized and adjusted.

(2) Based on the low-bed device, the height of the inactive area of the traditional resin bed is reduced, making full use of the resin in the column, greatly improving the exchange kinetics, increasing the batch waste liquid processing capacity, and increasing the acid concentration.

(3) The processing capacity per cycle increases, and the resin adsorption process in a single cycle basically reaches saturation, which improves the separation efficiency.

(4) The resin has stable performance, is easy to regenerate, can be reused, has low operating costs, and can meet the company's long-term stable production requirements.

Description of the drawings

The above and/or other advantages of the present invention will become more clear when the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is a schematic diagram of the low bed device (left: traditional ion exchange column; right: low bed exchange column).

Figure 2 shows the adsorption section curve when the salt-containing waste acid stock solution passes through the adsorption column.

Figure 3 shows the elution curve when the adsorption column is eluted with eluent.

Detailed ways

The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described can be obtained from commercial sources unless otherwise specified.

Each acid-containing waste liquid described in the following examples is shown in Table 1 respectively.

Table 1 Basic chemical properties of raw materials

raw material Metal salt content/(g/L) Acidity (calculated as H ⁺ )/(g/L) Iron and steel smelting plant ferric acid waste liquid 20 229 Electrode foil aluminum acid waste liquid 12 230 Electroplating factory waste liquid 15 220

In the following examples, the modified special strong base and strong acid (quaternary ammonium benzene sulfonic acid type) amphoteric resin has a particle size of 0.15-0.3 mm, a cross-linking degree of 2%, a moisture content of 80%, and a wet true density of 1.10g/cm ³ .

In the following examples, the modified special strong base and strong acid (quaternary ammonium alkyl benzene sulfonic acid type) snake cage resin has a particle size of 0.05 to 0.1 mm, a cross-linking degree of 4%, a moisture content of 60%, and a wet The true density is 1.08g/cm ³ .

In the following examples, the modified special strong base and weak acid (quaternary ammonium maleic acid type) amphoteric resin has a particle size of 0.05-0.15 mm, a cross-linking degree of 2%, a moisture content of 70%, and a wet The true density is 1.09g/cm ³ .

In the following examples, the strongly alkaline (quaternary ammonium type) anion exchange resin has a particle size of 0.15-0.3mm, a cross-linking degree of 8%, a water content of 40%, and a wet true density of 1.05g/cm ³ .

In the following examples, the height of the low-bed adsorption column is 80cm and the diameter is 50cm.

In the following examples, the loading amount and loading rate of salt-containing waste acid in each cycle, as well as the elution amount and elution rate of water, are the same as the parameters corresponding to the first cycle unless otherwise specified.

In the following embodiments, the precision filtration is to filter the salt-containing waste acid through a microfiltration membrane (filtration precision: 300-800), and the resulting filtrate is the precision-filtered salt-containing waste acid stock solution.

In the following examples, the filling height of the characteristic resin is 80 cm.

Example 1: A process for efficiently recovering waste acid using modified special resin, using salty waste liquid from a steel smelting plant. The process of the present invention includes the following steps:

(1) Before first use, use modified special strong base and strong acid (quaternary ammonium benzene sulfonic acid type) amphoteric resin to fill the low bed adsorption column, inject 10% NaCl in countercurrent and soak for 3 hours. After the resin shrinks, add new resin until the resin is replenished. The low bed device is filled with a modified special resin with an inner diameter of 10.5cm x a height of 15cm. The separator is then sealed and pure water is injected downstream to flush the resin column. The purpose is to wash away the salt on the resin and allow the resin to expand throughout the bed. The body is in a compacted state. During the pure water flushing process, be careful not to have any air in the resin bed and drain the water in the resin bed;

(2) The first cycle of adsorption is to pump the precision-filtered salt-containing waste acid stock solution (1L, flow rate 6BV/h) into the modified special strong alkali and strong acid resin column from the bottom, and collect 0.4L of the residue from the upper end. Wash water and 0.5L of deacidification salt solution. Then perform the first cycle of elution, using pure water (0.8L, flow rate 6BV/h) for elution. Pump the pure water downstream from the top into the elution blocking acid, and collect 0.4L of residual content from the bottom. Salt waste acid liquid, 0.5L desalted acid-containing liquid;

(3) In the second cycle, adsorption is performed first, and 0.4L of the residual salt-containing waste acid solution from the previous cycle is sequentially fed from the lower end of the column, and then 0.8L of the salt-containing waste acid stock solution is fed. Similarly, 0.4L of residual elution water and 0.5L of deacidified salt-containing liquid were collected from the upper end. Then perform elution, sequentially add 0.4L of residual elution water from the previous cycle, and then add 0.8L of pure water for downstream elution. Similarly, 0.4L of residual waste acid liquid and 0.5L of desalted acid-containing liquid are collected from the lower end;

(4) Repeat the above process for the second cycle 3 times. The final average results are shown in Table 2.

Example 2: A process for efficiently recovering waste acid using modified special resin, using the salt-containing waste liquid of a certain electrode foil aluminum waste acid. The process of the present invention includes the following steps:

(1) Before first use, use modified special strong base and strong acid (quaternary ammonium alkyl benzene sulfonic acid type) snake cage resin to fill the low bed adsorption column, inject 10% NaCl in countercurrent and soak for 3 hours. After the resin shrinks, add new resin. Until the resin is fully replenished, a special resin with an inner diameter of 10.5cm x a height of 15cm is installed in the low-bed device. Then the separator is sealed and pure water is injected downstream to flush the resin column. The purpose is to wash away the salt on the resin and allow the resin to expand throughout the system. The bed is in a compacted state. During the pure water flushing process, attention should be paid to the absence of any air in the resin bed and the moisture in the resin bed should be drained;

(2) The first cycle of adsorption is to pump the precision-filtered salt-containing waste acid stock solution (2L, flow rate 6BV/h) from the bottom into the modified special strong alkali and strong acid type snake cage resin column, and collect 0.8L from the upper end. of residual elution water and 1.2L of deacidification salt-containing solution. Then perform the first cycle of elution, using pure water (1.8L, flow rate 6BV/h) for elution. Pump the pure water downstream from the top into the elution blocking acid, and collect 0.8L of residual content from the bottom. Salt waste acid liquid, 1.2L desalted acid-containing liquid;

(3) In the second cycle, adsorption is performed first, and 0.8L of the residual salt-containing waste acid solution from the previous cycle is sequentially fed from the lower end of the column, and then 1L of the salt-containing waste acid stock solution is fed. Similarly, 0.8L of residual elution water and 1.2L of deacidified salt-containing liquid were collected from the upper end. Then perform elution, sequentially add 0.8L of residual elution water from the previous cycle, and then add 2.0L of pure water for downstream elution. Similarly, 0.8L of residual waste acid liquid and 1.2L of desalted acid-containing liquid are collected from the lower end;

(4) Repeat the above process for the second cycle 3 times. The final average results are shown in Table 2.

Example 3: A process for efficiently recovering waste acid using modified special resin, using salt-containing waste liquid from an electroplating factory. The process of the present invention includes the following steps:

(1) Before first use, use modified special strong base weak acid (quaternary ammonium maleic acid type) amphoteric resin to fill the low bed adsorption column, inject 10% NaCl in countercurrent and soak for 3 hours. After the resin shrinks, add new resin. Until the resin is fully replenished, a special amphoteric resin with an inner diameter of 10.5cm x a height of 15cm is installed in the low-bed device. Then the separator is sealed and pure water is injected downstream to flush the resin column. The purpose is to wash away the salt on the resin and allow the resin to expand. The entire bed is in a compacted state. During the pure water flushing process, attention should be paid to the absence of any air in the resin bed and the moisture in the resin bed should be drained;

(2) The first cycle of adsorption is to pump the precision-filtered salt-containing waste acid stock solution (3L, flow rate 8BV/h) into the modified special strong alkali and strong acid resin column from the bottom, and collect 1.2L of the residue from the upper end. Wash water and 1.75L of deacidification salt solution. Then perform the first cycle of elution, using pure water for elution. Pure water (3L, flow rate 8BV/h) is pumped from the top into the elution blocking acid, and 1L of residual salt-containing waste is collected from the bottom. Acid liquid, 1.75L of desalted acid-containing liquid;

(3) In the second cycle, adsorption is performed first, and 1L of the residual salt-containing waste acid solution of the previous cycle is sequentially fed from the lower end of the column, and then 1.5L of the salt-containing waste acid stock solution is fed. Similarly, 0.8L of residual elution water and 1.75L of deacidified salt-containing liquid were collected from the upper end. Then perform elution, sequentially add 0.8L of residual elution water in the previous cycle, and then add 2.75L of pure water for downstream elution. Similarly, 1L of residual waste acid liquid and 1.75L of desalted acid-containing liquid were collected from the lower end;

(4) Repeat the above process for the second cycle 3 times. The final average results are shown in Table 2.

Comparative Example 1: Utilize strong alkaline anion exchange resin to efficiently recover waste acid, using salty waste liquid from a steel smelting plant. The process of the present invention includes the following steps:

(1) Before first use, use strong alkaline (quaternary ammonium type) anion exchange resin to fill the low-bed adsorption column, inject 10% NaCl in countercurrent and soak for 3 hours. After the resin shrinks, add new resin until the resin is filled and the low-bed column is filled. The device is equipped with a strong alkaline anion exchange resin with an inner diameter of 10.5cm x a height of 15cm. The separator is then sealed and pure water is injected downstream to flush the resin column. The purpose is to wash away the salt on the resin and allow the resin to expand and the entire bed to be under pressure. In the solid state, during the pure water flushing process, pay attention to the fact that there cannot be any air in the resin bed and drain the water in the resin bed;

(2) In the first cycle of adsorption, the precision-filtered salt-containing waste acid stock solution (1L, 3BV/h) is counter-currently pumped into the strong alkaline anion exchange resin column from the bottom, and 0.4L of residual elution water is collected from the top. , 0.5L deacidification salt-containing liquid. Then perform the first cycle of elution, using pure water for elution. Pure water (1L, 3BV/h) is pumped from the top into the elution blocking acid, and 0.4L of residual salt-containing waste is collected from the bottom. Acid solution, 0.5L desalted acid-containing solution;

(3) In the second cycle, adsorption is performed first, and 0.4L of the residual salt-containing waste acid solution from the previous cycle is sequentially fed from the lower end of the column, and then 0.8L of the salt-containing waste acid stock solution is fed. Similarly, 0.4L of residual elution water and 0.5L of deacidified salt-containing liquid were collected from the upper end. Then perform elution (1L, 3BV/h), sequentially add 0.4L of residual elution water from the previous cycle, and then add 0.8L of pure water for downstream elution. Similarly, 0.4L of residual waste acid liquid and 0.5L of desalted acid-containing liquid are collected from the lower end;

(4) Repeat the above process for the second cycle 3 times. The final average results are shown in Table 2.

The ferrous salt-containing effluent (i.e., desalted salt-containing liquid) and the sulfuric acid-containing effluent (i.e., desalted acid-containing liquid) obtained in the above examples and comparative examples were analyzed by the following method (wherein, the effluents of the same steps were Combined) for testing, the specific test results are shown in Table 2. In addition, the first phase adsorption and elution curves in the above-mentioned Example 1 and Example 2 are shown in Figure 2 and Figure 3 respectively.

Detection method for metal salt content: atomic absorption spectrometer;

Detection method of acid content: acid-base indicator titration method;

The calculation formula for salt yield is:

The calculation formula for acid yield is:

The calculation formula of acid concentration C/C ₀ is:

Table 2 Main performance indicators for efficient separation and recovery of metal salts and acid solutions from waste acid solutions

serial number Acid yield/% Salt yield/% C/C ₀ Example 1 99.8 93.10 0.92 Example 2 99.9 95.55 0.90 Example 3 99.9 92.30 0.91 Comparative example 1 70.1 78.31 0.64

It can be seen from the data in Table 2 above that the acid recovery rate of the recovery method of the present invention can reach more than 99.8%. The modified special resin can achieve efficient separation in steel waste liquid, electroplating waste liquid and aluminum acid waste liquid. Moreover, the concentration C/C ₀ of the dilute acid solution obtained by the treatment can reach more than 0.9, which has a good acid recovery effect. Moreover, increasing the recovery concentration of acid and the amount of metal recovery can significantly shorten the processing time of waste acid, shorten the processing cycle, and reduce energy consumption.

In summary, the present invention adopts non-ion exchange adsorption technology, utilizes modified special resin and low-bed device (Figure 1), and fundamentally achieves efficient separation of acids and salts. This resin is different from the strongly alkaline ion exchange resin commonly used in acid blocking technology. Its separation mechanism is adsorption distribution rather than acid blocking. At the same time, the supporting low bed equipment can well meet the needs of acids and salts. requirements for efficient separation. The resin used in the present invention can not only adsorb acid but not the corresponding metal salt, but can also significantly improve the acid accumulation problem currently caused by using strong alkaline ion exchange resin to treat waste acid, thereby truly realizing the high efficiency of salt and acid. Separation greatly improves the yield and concentration of acid, and the resin structure has stable performance and long service life, which can meet the requirements of industrial production and can be promoted and applied on a large scale. Except for water, no chemical reagents are needed here. The resin bed that has adsorbed strong acid only needs to be washed with water to achieve acid elution and resin regeneration. The resin can be used in the next cycle without regeneration, and the operating cost is low. , short production cycle.

The present invention provides a process idea and method for efficiently recovering waste acid using modified special resin. There are many specific solutions and ways to realize this technology. The above is only the preferred embodiment of the present invention. It should be pointed out that for this technical field, Those of ordinary skill can make several improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented using existing technologies.

Claims (12)

1. A process for efficiently recovering acid and salt using modified special resin, which is characterized by including the following steps: S1: Load the salt-containing waste acid into the low-bed adsorption column from bottom to top, and collect the effluent from the upper end of the low-bed adsorption column; the residual elution water is collected first. When the salt content in the effluent is When it is 0~1g/L, start collecting the deacidified salt-containing liquid; S2: When the effluent in step S1 contains acid, pass water from top to bottom into the low-bed adsorption column for elution, and collect the lower effluent; the residual salt-containing waste acid is collected first. When the effluent contains When the salt content begins to decrease, start collecting the desalted acid-containing liquid; Wherein, the low-bed adsorption column is a low-bed adsorption column containing modified special resin; Wherein, the modified special resin is a quaternary ammonium benzene sulfonic acid type strong base strong acid type amphoteric polymeric resin with styrene-divinylbenzene as the main structure, or a quaternary ammonium maleic acid type strong base weak acid type amphoteric polymer resin Polymer resin; degree of cross-linking is 2-10%. 2. The process according to claim 1, characterized in that the particle size of the amphoteric polymer resin is 0.05~0.3 mm, the moisture content is 40%~80%, and the wet true density is 1.05~1.10 g/ ^cm3 . 3. The process according to claim 1, characterized in that the height of the low-bed adsorption column is 0.1~3.0 m, and the diameter is 0.1~3.0 m. 4. The process according to claim 1, characterized in that in step S1, the loading amount of the salt-containing waste acid is 1~5BV. 5. The process according to claim 1, characterized in that in step S1, the sample loading rate is 1~10 BV/h. 6. The process according to claim 1, characterized in that in step S2, the amount of water used is 1~5BV. 7. The process according to claim 1, characterized in that in step S2, the elution rate is 1~10 BV/h. 8. The process according to claim 1, characterized in that the collection amount of the residual washing water is 0.1~2.5 BV. 9. The process according to claim 1, characterized in that the collection amount of the deacidified salt-containing liquid is 0.2~1.5 BV. 10. The process according to claim 1, characterized in that the collection amount of the residual salt-containing waste acid is 0.1~2.5 BV. 11. The process according to claim 1, characterized in that the collection amount of the desalted acid-containing liquid is 0.2~1.5 BV. 12. The process according to claim 1, characterized in that, in step S1, the salt-containing waste acid is a salt-containing waste acid stock solution and/or residual salt-containing waste acid; in step S2, the water is newly injected water and/or residual elution water.