Method for resource utilization of pickling waste liquid and waste water

Abstract

The invention belongs to the technical field of resource recycling, and discloses a method for resource utilization of pickling waste liquid and wastewater, which comprises the following steps: firstly, filtering nitric acid and hydrofluoric acid pickling liquid of a titanium material to remove insoluble solids as raw water, and adding an organic complexing agent for complexing fluorine ions; adding CaO into the solution to adjust the pH value, and filtering to obtain filtrate and titanium-rich precipitate; h2O2 / Fe is added into the filtrate for oxidation and complex breaking, then CaO is added to adjust the pH value, and filtrate and fluorine-rich precipitates are obtained after filtering. Putting a composite adsorbent into the filtrate for deep defluorination, performing high-salt reverse osmosis multi-stage concentration on the filtered solution to obtain a 15-18wt% calcium nitrate solution, supplementing nitric acid and ammonia water according to the proportion of calcium ammonium nitrate, and finally evaporating the solution to obtain a solid calcium ammonium nitrate product. And a concentrated solution can be obtained and is directly used for drip irrigation. According to the method, titanium material pickling solution resources can be effectively utilized, and great economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of resource recycling and utilization, and relates to a method for resource utilization of pickling waste liquid and waste water. Technical Background

[0002] Titanium pickling solution is a chemical solution used to remove pollutants from the surface of titanium materials, including acidic substances, corrosion inhibitors, surfactants and inhibitors. During the production and processing of titanium materials, the pickling solution will gradually lose its effectiveness and accumulate impurities to become waste liquid, or be discharged as wastewater. The traditional treatment method uses lime and alkali solution for neutralization and precipitation, which not only forms sludge but also causes resource waste and environmental pollution. Therefore, it is particularly important to develop a method for resource utilization of titanium pickling solution.

[0003] For common steel pickling wastewater, traditional treatment methods usually use lime, carbide slag or the product of lime nitration reaction Ca(OH)2 for neutralization. However, this method will produce sludge that is difficult to handle and waste acid and metal resources. In contrast, resource-based treatment methods can turn waste into treasure while treating waste. Methods for resource utilization of pickling liquid include complex precipitation, concentrated crystallization and neutralization. These methods can not only reduce environmental pollution, but also effectively recycle and utilize the useful components therein, and have important economic and environmental value.

[0004] For example, in the Chinese invention patent "Method for Recycling Titanium and Titanium Alloy Pickling Waste Liquid" (patent number: CN86104454), Cao Junqing and Wang Guoxing of Northwest Institute of Nonferrous Metals adopted the complex precipitation method of adding sodium fluoride to precipitate titanium ions and other impurity ions in the waste pickling liquid, and added 20% nitric acid and 80% hydrofluoric acid to the filtrate to achieve the effect of new acid preparation. The precipitate can be used for corrosion protection, enamel and plastic industries, and can also be converted into hydrofluoric acid and titanium dioxide. In the Chinese invention patent "A Method for Regenerating Titanium Metal Pickling Waste Liquid" (patent number: CN202411214292.9), Zhang Jingtao and others invented a method for regenerating titanium metal pickling waste liquid, adding fluorosilicic acid solution to titanium metal pickling waste liquid and mixing evenly, then adding potassium salt solution, stirring the reaction at room temperature, centrifuging or filtering after the reaction is completed, and the solid part is potassium fluorotitanate / potassium fluorosilicate complex; the liquid part is the regenerated titanium metal pickling liquid. In the Chinese invention patent "A method for preparing nano-anatase titanium dioxide from cold-rolled titanium pickling waste liquid" (patent number: CN202010543554.1), Wei Keyi and others invented a method for preparing nano-anatase titanium dioxide from cold-rolled titanium pickling waste liquid, comprising the following steps: ① adjusting the cold-rolled titanium pickling waste liquid to a pH value of 1-3, then aging the solution and separating it, and drying the obtained precipitate to obtain a metatitanic acid precursor; ② calcining the metatitanic acid precursor obtained in step ①, and cooling it to obtain the nano-anatase titanium dioxide. The method of this invention can directly obtain nano-anatase titanium dioxide, realizing efficient recycling of titanium resources. There is also a method of recovering hydrofluoric acid or nitric acid by heating and distillation after adding acid. The main problem of the above-mentioned acid recovery method is that it inevitably increases corrosiveness and has high requirements for equipment, and the quality of the product is not high. For nitrates, the sodium nitrate or ammonium nitrate produced after neutralization also has the danger of explosion.

[0005] In order to solve the problem of nitrate ion being explosive and to solve the problem of wastewater resource utilization, it is necessary to seek nitrate substances that are not easy to explode. Due to the presence of calcium, the nitrogen content of calcium ammonium nitrate, an agricultural fertilizer, is lower than that of ordinary ammonium nitrate, and its hygroscopicity is lower than that of ordinary ammonium nitrate, thereby improving the agglomeration and thermal stability. It is not easy to cause fire and explosion during storage and transportation, and is a safe nitrate nitrogen fertilizer. As a modified alternative product of ammonium nitrate, it meets the current and future market demand and has broad development prospects.

[0006] Therefore, the present invention has developed a method for resource utilization of titanium pickling liquid, which enriches the metal elements titanium and elemental fluorine from the perspective of resource recycling, and further utilizes the ammonia nitrogen and titanium nitrate nitrogen therein to prepare calcium ammonium nitrate products, thereby realizing resource utilization and extension of the industrial chain. Summary of the invention

[0007] In order to solve the above problems, the present invention aims to provide a new method for resource utilization of titanium acid waste liquid and waste water. In this way, the titanium acid waste liquid and waste water can be effectively treated to avoid environmental pollution, and the titanium and fluorine in the acid waste liquid and waste water can be enriched. The final product, calcium ammonium nitrate, can also be used as a fertilizer, greatly improving the economic and environmental benefits.

[0008] The technical solution of the present invention:

[0009] A method for resource utilization of pickling waste liquid and wastewater, the steps are as follows:

[0010] Use nitric acid and hydrofluoric acid of different concentrations to clean the corresponding titanium material, first filter the waste liquid and waste water obtained after cleaning to remove insoluble solids, and obtain waste liquid and waste water without insoluble solids as raw water; then add an organic complexing agent to the raw water to complex fluoride ions, then add CaO to adjust the pH, and filter to obtain filtrate 1 and titanium-rich precipitate residue; add a complexing agent to the filtrate 1 to oxidize and break the complex, then add CaO to adjust the pH, and filter to obtain filtrate 2 and fluorine-rich precipitate; add a composite adsorbent to the filtrate 2 for deep fluorine removal, and the filtered solution is concentrated in multiple stages by a concentration membrane group to obtain a 15-18wt% calcium nitrate solution, nitric acid and ammonia water are added according to the ammonium nitrate calcium ratio, and then evaporate the solution to obtain a calcium ammonium nitrate product.

[0011] The organic complexing agent is a substance containing hydroxyl or amino and anthraquinone functional groups, such as 1,2-dihydroxyanthraquinone and 3-methylamine-alizarin diacetate; the mass ratio of the organic complexing agent to fluorine is 1-1.5:1, ensuring that the fluoride ions in the solution are completely complexed;

[0012] CaO adjusts the pH of filtrate 1 to 3-4;

[0013] The complex breaking agent is to add H2O2 and / or Fe element, or Fe 2+ , where Fe element and Fe 2+ It is not advisable to add too much to avoid introducing more impurities. The amount of Fe element added is used to destroy the complex structure of fluoride ions. The amount added is related to the fluoride ion concentration in the raw water. The molar ratio of the added Fe element to the F ion should be between 0.7 and 2; the amount of H2O2 added should also be controlled so that the molar ratio of H2O2 to F ions should be between 0.7 and 2.

[0014] CaO adjusts the pH of filtrate 2 to 8.5-9;

[0015] The composite adsorbent is a composite adsorbent of bone char and inorganic magnesium aluminum oxide, and the dosage is controlled to meet the requirement of fluorine ≤ 1 mg / L or lower after defluorination;

[0016] The filter membranes used in the concentration membrane group are RO membrane and HSRO membrane, and a multi-stage concentration method is adopted. The concentration of concentrated calcium nitrate is 15-18wt% (% mentioned in the text are all mass fractions); the effluent meets TDS≤1000mg / L and pH is 6.5-9.5;

[0017] The chemical formula of the resulting calcium ammonium nitrate product is 5Ca(NO3)2·NH4NO3·10H2O.

[0018] Add nitric acid and ammonia to the solution n(Ca):n(NO 3- ): n(NH 4+ )=5:11:1, and a solid product containing crystal water is obtained by evaporation.

[0019] Beneficial effects of the present invention:

[0020] Most nitrate solids are strictly controlled as explosive substances. Wastewater resource utilization requires the solids to be evaporated to obtain solids. The evaporation of nitrates such as sodium nitrate, ammonium nitrate, and calcium nitrate has high explosion-proof requirements and strict management. It requires a safer production environment and equipment. As a waste resource utilization, the preparation cost is relatively high.

[0021] Calcium ammonium nitrate is a safe fertilizer material with low explosion-proof safety and easy production, so it is suitable as a product for the resource utilization of nitrate wastewater. The wastewater resources targeted by this patent are wastewater with nitrate, ammonium and calcium ions as the main components, which are suitable for conversion using the design method of this patent.

[0022] Currently, there is no technology for preparing calcium ammonium nitrate by recycling wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention;

[0024] Figure 2 The infrared spectra of the composite adsorbent before and after adsorption;

[0025] Figure 3 This is the infrared spectrum of the product in Example 1;

[0026] Figure 4 This is the infrared spectrum of the product in Example 2. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0028] Example 1: Resource recovery of titanium pickling wastewater

[0029] 1L of acid-washing waste liquid from which insoluble solids were removed was measured to have a pH of 0.80. The concentrations of various ions in the solution were measured using ICP-OES, the concentration of nitrate nitrogen was measured using UV spectrophotometry, and the concentration of fluoride ions in the solution was measured using a fluoride ion electrode. The results are shown in Table 1:

[0030] Table 1 Ion concentrations of titanium acid waste liquid and wastewater

[0031]

[0032] Nitrate nitrogen in acidic wastewater is about 7.8g / L (equivalent to NO3 - About 34.54g / L), fluorine concentration is about 7.2g / L. - The presence of Ca 2+ The concentration is close to 0, and Mg, P, As and other heavy metal elements are not detected.

[0033] In the first step, according to the fluorine concentration, an equimolar amount of organic complexing agent 3-methylamine-alizarin diacetic acid is added to the solution, and then CaO powder is added to adjust the pH to 3.7, and filtered. The precipitate and the filtrate are analyzed: the main components of the precipitate are Ca and Ti, with contents of 39.2% and 20.4% respectively. In addition, the precipitate is also mixed with a small amount of Al and Fe. At this time, the F in the solution - There was a slight decrease, while NO3 - The concentration has basically not changed, and Al and Fe in the solution have been completely precipitated.

[0034] In the second step, add appropriate amount of H2O2 and a small amount of Fe to the filtrate of the first step. 2+ The chelate was broken by oxidation, and then CaO powder was added to the filtrate to adjust the pH to 8.5 and filter. The precipitate and filtrate were analyzed: the precipitate was mainly composed of CaF2, mixed with a small amount of Fe. - The concentration is 90mg / L, NO3 - The concentration remained basically unchanged, Ca 2+ The concentration is 11.2 g / L, which means that the main component of the solution is Ca(NO3)2.

[0035] In the third step, 20 g of bone carbon / LDH composite adsorbent was added to the filtrate of the second step, and the mixture was filtered and the F was determined after 1 h of shaking adsorption. - Concentration, after detection of adsorption F - The concentration is less than 1 mg / L. The infrared spectra of bone charcoal / LDH adsorbent before and after adsorption are shown in the attached figure. Figure 2 shown.

[0036] In the fourth step, the solution is added to a flat membrane device for concentration. The membrane group is composed of an RO membrane and a HSRO membrane. After five concentrations, the calcium nitrate concentration in the solution reaches 15%; the effluent TDS is 800 mg / L, and the pH is measured to be 7.5.

[0037] Step 5: Add 3.7 ml of nitric acid and 3.8 ml of ammonia water (based on the nitrate concentration) to the concentrated Ca(NO3)2 solution, and then place the solution in an evaporating dish for evaporation. After evaporation, a yellow-white solid is obtained, and the infrared spectrum is as follows: Figure 3 As shown in the figure, compared with the dry calcium ammonium nitrate, the product obtained in Example 1 has a -1 There is an obvious absorption peak near 1450-1300cm, which is caused by the vibration of the -OH bond in H2O, indicating the presence of crystal water in the obtained product. -1 There is obvious NO3 - Absorption peak.

[0038] Example 2: Titanium pickling wastewater from a comprehensive pool of a titanium production enterprise

[0039] The composition of wastewater, pH = 3, the concentration of each ion in the solution was determined by ICP-OES, the concentration of nitrate nitrogen was determined by UV spectrophotometry, and the concentration of fluoride ions in the solution was determined by a fluoride ion electrode. The results are shown in Table 1:

[0040] Table 2 Ion concentrations of titanium acid waste liquid and wastewater

[0041]

[0042] In the first step, according to the fluorine concentration, an equimolar amount of organic complexing agent 1,2-dihydroxyanthraquinone (the organic complexing agent is used to complex fluorine) is added to the solution, and then CaO powder is added to adjust the pH to 4 and filter. The precipitate and the filtrate are analyzed: the main components of the precipitate are Ca and Ti, with contents of 40.2% and 19.9% ​​respectively. In addition, the precipitate is also mixed with a small amount of Al and Fe. At this time, the F in the solution - The concentration decreased by about 5%, while NO3 - The concentration has basically not changed, and Al and Fe in the solution have been completely precipitated.

[0043] In the second step, add H2O2 and a small amount of Fe to the filtrate from the first step. 2+ The filtrate was oxidized and then CaO powder was added to adjust the pH to 9 and filtered. The precipitate and filtrate were analyzed: the precipitate was mainly composed of CaF2. - The concentration is 10mg / L, NO3 - The concentration remained basically unchanged, Ca 2+The concentration is 11.8 g / L, which means that the main component of the solution is Ca(NO3)2.

[0044] In the third step, 15 g of composite adsorbent was added to the filtrate of the second step, and the mixture was filtered and the F was determined after 1 h of shaking adsorption. - Concentration, after detection of adsorption F - The concentration is less than 1mg / L.

[0045] In the fourth step, the solution was added to a flat membrane device for concentration. After five concentrations, the concentration of calcium nitrate in the solution reached 15%; the effluent TDS was 950 mg / L, and the pH was measured to be 8.4.

[0046] Step 5: Add 10.4 ml of nitric acid and 4.4 ml of ammonia water (based on the calcium ion concentration) to the concentrated Ca(NO3)2 solution, and then place the solution in an evaporating dish for evaporation. After evaporation, a yellow-white solid is obtained, and the infrared spectrum is as follows: Figure 4 As shown in the figure, only at 3202.2cm -1 The product obtained in Example 2 is different from the dried calcium ammonium nitrate except that the hydroxyl peak fluctuates due to the presence of crystal water. The other absorption peaks can correspond to calcium ammonium nitrate and are in the range of 1450-1300 cm -1 There is obvious NO3 - Absorption peak.

Claims

1. A method for resource utilization of pickling waste liquid and wastewater, characterized in that: Here are the steps: Use nitric acid and hydrofluoric acid of different concentrations to clean the corresponding titanium material, first filter the waste liquid and waste water obtained after cleaning to remove insoluble solids, and obtain waste liquid and waste water without insoluble solids as raw water; then add an organic complexing agent to the raw water to complex fluoride ions, then add CaO to adjust the pH, and filter to obtain filtrate 1 and titanium-rich precipitate residue; add a complexing agent to the filtrate 1 to oxidize and break the complex, then add CaO to adjust the pH, and filter to obtain filtrate 2 and fluorine-rich precipitate; add a composite adsorbent to the filtrate 2 for deep fluorine removal, and the filtered solution is concentrated in multiple stages by a concentration membrane group to obtain a 15-18wt% calcium nitrate solution, nitric acid and ammonia water are added according to the ammonium nitrate calcium ratio, and then evaporate the solution to obtain a calcium ammonium nitrate product.

2. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The organic complexing agent is a substance containing a hydroxyl group or an amino group and an anthraquinone functional group; the mass ratio of the organic complexing agent to fluorine is 1-1.5:

1.

3. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The organic complexing agent is 1,2-dihydroxyanthraquinone or 3-methylamine-alizarin diacetic acid.

4. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The CaO is used to adjust the pH of the filtrate 1 to 3-4.

5. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The complex breaking agent is H2O2 and / or Fe element, or Fe 2+ The molar ratio of the added Fe element to the F ion should be between 0.7 and 2; the amount of added H2O2 should also be controlled so that the molar ratio of H2O2 to F ion is between 0.7 and 2.

6. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The CaO adjusts the pH of the filtrate 2 to 8.5-9.

7. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The composite adsorbent is a composite adsorbent of bone carbon and inorganic magnesium aluminum oxide, and the dosage is controlled to meet the requirement of fluorine ≤ 1 mg / L or lower after fluorine removal.

8. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The filter membranes used in the concentration membrane group are RO membranes and HSRO membranes, and a multi-stage concentration method is adopted. The concentration of concentrated calcium nitrate is 15-18wt%; the effluent meets TDS≤1000mg / L and pH is 6.5-9.

5.

9. The method for resource utilization of pickling waste liquid and wastewater according to claim 1, characterized in that: The addition of nitric acid and ammonia to the solution n(Ca):n(NO 3- ): n(NH 4+ )=5:11:1, and a solid product containing crystal water is obtained by evaporation.

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