A resource treatment process of iron-containing waste acid solution

Abstract

The present application relates to waste acid resource utilization technical field, propose a kind of resource processing technology of iron-containing waste acid solution, comprising the following steps: S1, after the ferrous ion in iron-containing waste acid solution is oxidized into iron ion, extract by composite extractant, obtain iron-containing organic phase and regenerated acid-containing aqueous phase;S2, after iron-containing organic phase is back-extracted by water, obtain iron-containing wastewater and regenerated organic phase;S3, iron-containing wastewater is used to prepare iron-containing compound;Composite extractant includes diluent, trialkyl phosphine oxide and alkyl phosphonic acid dialkyl ester.Through the above technical scheme, the problem that acid is wasted due to the treatment process of iron-containing waste acid solution in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of waste acid resource utilization technology, specifically to a resource utilization process for iron-containing waste acid solutions. Background Technology

[0002] Iron-containing waste acid solutions are mainly generated in the pickling process of the metal surface treatment industry. During steel processing and manufacturing, pickling is necessary to improve the surface quality, rust prevention, and subsequent coating effects of the steel. However, as pickling progresses, the concentration of iron ions dissolved in the solution continuously increases. When the iron salt content in the pickling solution reaches saturation, and the pickling effect can no longer meet process requirements, new acid must be used, thus generating iron-containing waste acid solutions.

[0003] Currently, there are many treatment processes for iron-containing waste acid solutions, mainly involving the direct use of the solution as a raw material to prepare iron-containing compounds. However, this results in the waste of acid in the iron-containing waste acid solution. Therefore, there is an urgent need to provide a resource-based treatment process for iron-containing waste acid solutions, enabling the reuse of both iron and acid in the solution. Summary of the Invention

[0004] This invention proposes a resource-based treatment process for iron-containing waste acid solutions to solve or alleviate at least one of the above-mentioned problems.

[0005] The technical solution of the present invention is as follows: This invention proposes a resource-based treatment process for iron-containing waste acid solution, comprising the following steps: S1. After oxidizing ferrous ions in the iron-containing waste acid solution to ferric ions, the solution is extracted with a composite extractant to obtain an iron-containing organic phase and a regenerated acid-containing aqueous phase. S2. The iron-containing organic phase is back-extracted with water to obtain iron-containing wastewater and a regenerated organic phase; S3. Use the iron-containing wastewater to prepare iron-containing compounds; The composite extractant includes a diluent, trialkyl phosphorus oxide, and dialkyl alkyl phosphonate.

[0006] Preferably, the mass ratio of the trialkyl phosphorus oxide and the dialkyl alkyl phosphonate to the diluent is 0.5 to 1:1.

[0007] Preferably, the mass ratio of the trialkyl phosphorus oxide to the dialkyl alkyl phosphonate is 2:3 to 3:7.

[0008] Preferably, the diluent is sulfonated kerosene.

[0009] Preferably, the alkylphosphonate dialkyl ester includes one or both of dimethylheptyl methylphosphonate and dibutyl butyl phosphate.

[0010] Preferably, oxidizing ferrous ions in an iron-containing waste acid solution to ferric ions includes the following steps: mixing the iron-containing waste acid solution with activated carbon powder, and oxidizing ferrous ions to ferric ions in an oxygen atmosphere.

[0011] Preferably, the mass-to-volume ratio of the activated carbon powder to the iron-containing waste acid solution is 0.5~1g:500mL.

[0012] Preferably, step S3 includes the following steps: mixing the iron-containing wastewater with hydrochloric acid to obtain an iron-containing acid solution; mixing the iron-containing acid solution with aluminum ash at 85~90℃ to react; after the reaction is completed, adding sodium fatty acid methyl ester sulfonate and polyacrylamide, stirring and allowing it to stand to separate into layers, the supernatant is polyaluminum ferric chloride.

[0013] Preferably, the concentration of hydrochloric acid in the iron-containing acid solution is 15wt%~20wt%.

[0014] Preferably, the mass ratio of the ferric acid solution to the aluminum ash is 3~3.5:1.

[0015] The working principle and beneficial effects of this invention are as follows: This invention provides a resource-based treatment process for iron-containing waste acid solution. First, ferrous ions in the iron-containing waste acid solution are oxidized to ferric ions. Then, an extractant composed of a diluent, trialkyl phosphorus oxide, and dialkyl alkyl phosphonate is used to extract the ferric ions. This composite extractant has a good extraction effect on ferric ions. After extraction, iron and acid can be well separated. The acid-containing aqueous phase can be regenerated and recycled. The iron-containing organic phase can be back-extracted with water and then regenerated and recycled. The iron-containing wastewater can be used to prepare a series of iron-containing compounds, such as polyaluminum ferric chloride, ferric oxide, ferric hydroxyl oxide, and ferric phosphate. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] A specific embodiment of the present invention provides a resource-based treatment process for iron-containing waste acid solution, comprising the following steps: S1. After oxidizing ferrous ions in the iron-containing waste acid solution to ferric ions, the solution is extracted with a composite extractant to obtain an iron-containing organic phase and a regenerated acid-containing aqueous phase. S2. After back-extracting the iron-containing organic phase with water, iron-containing wastewater and regenerated organic phase are obtained; S3. Using iron-containing wastewater to prepare iron-containing compounds; The compound extractant includes a diluent, trialkyl phosphorus oxide, and dialkyl alkyl phosphonate.

[0018] In this invention, ferrous ions are converted into ferric ions and ferric acid is separated by a combination of oxidation and extraction. The regenerated acidic aqueous phase can be reused in the pickling process, significantly reducing acid consumption. After back-extraction of the iron-containing organic phase, the regenerated organic phase can be recycled, resulting in low operating costs and reduced organic solvent consumption and secondary pollution risks. The iron-containing wastewater obtained from back-extraction can be further treated to prepare valuable iron-containing compounds, such as polyaluminum ferric chloride, ferric oxide, ferric hydroxide, and ferric phosphate, achieving high-value utilization of iron resources and turning waste into treasure.

[0019] In one embodiment of the present invention, the mass ratio of trialkyl phosphorus oxide and dialkyl alkyl phosphonate to diluent is 0.5 to 1:1.

[0020] In one embodiment of the present invention, the mass ratio of trialkyl phosphorus oxide to dialkyl alkyl phosphonate is 1:1 to 1:7, preferably 2:3 to 3:7.

[0021] In this invention, the mass ratio of trialkyl phosphorus oxide and dialkyl alkyl phosphonate to diluent is limited to 0.5~1:1, while the mass ratio of trialkyl phosphorus oxide to dialkyl alkyl phosphonate is 2:3~3:7. This improves the selectivity of the extractant, increases the extraction efficiency, effectively enriches the iron resources in waste acid, and further improves the iron removal rate and the purity of polyaluminum ferric chloride.

[0022] In one embodiment of the present invention, the diluent is sulfonated kerosene.

[0023] In this invention, sulfonated kerosene is used as a diluent. Sulfonated kerosene is kerosene that has undergone a sulfonation process. The sulfonation reaction removes unsaturated hydrocarbons and other active components from the kerosene, avoiding the problem that unsaturated hydrocarbons are prone to oxidation during extraction, which could disrupt the extraction equilibrium and affect the phase separation effect. Simultaneously, sulfonated kerosene, as an inert solvent, does not chemically react with metal ions, effectively adjusting the concentration of the extractant and controlling the extraction capacity.

[0024] In one embodiment of the present invention, the alkylphosphonate dialkyl ester includes one or both of dimethylheptyl methylphosphonate and dibutyl butyl phosphate.

[0025] In one embodiment of the present invention, oxidizing ferrous ions in an iron-containing waste acid solution to ferric ions includes the following steps: mixing the iron-containing waste acid solution with activated carbon powder, and oxidizing ferrous ions to ferric ions in an oxygen atmosphere.

[0026] In this invention, activated carbon powder is added to an iron-containing waste acid solution and oxidized in an oxygen atmosphere. The rich pore structure and catalytic active sites on the surface of the activated carbon powder significantly accelerate the conversion of ferrous ions to ferric ions in the presence of oxygen.

[0027] In one embodiment of the present invention, the mass-to-volume ratio of activated carbon powder to iron-containing waste acid solution is 0.5~1g:500mL.

[0028] In this invention, the mass-to-volume ratio of activated carbon powder to iron-containing waste acid solution is controlled within the range of 0.5~1g:500mL, which ensures sufficient catalytic active sites while avoiding cost waste caused by excessive addition.

[0029] In one embodiment of the present invention, step S3 includes the following steps: mixing iron-containing wastewater with hydrochloric acid to obtain iron-containing acid solution; mixing the iron-containing acid solution with aluminum ash at 85~90°C for reaction; after the reaction is completed, adding sodium fatty acid methyl ester sulfonate and polyacrylamide, stirring and allowing to stand for separation, the supernatant is polyaluminum ferric chloride.

[0030] In this invention, iron-containing wastewater is mixed with hydrochloric acid to prepare an iron-containing acid solution, which is then reacted with aluminum ash at 85-90°C. Through the synergistic effect of aluminum in the aluminum ash and iron in the iron-containing acid solution, polyaluminum ferric chloride, an inorganic polymeric coagulant, is generated. Subsequently, sodium methyl ester sulfonate of fatty acids and polyacrylamide are added as coagulant aids and flocculants. After stirring, settling, and stratification, the supernatant is the finished polyaluminum ferric chloride, realizing the resource utilization of iron-containing wastewater, turning waste into treasure, and reducing environmental treatment costs.

[0031] In one embodiment of the present invention, the concentration of hydrochloric acid in the ferric acid solution is 15wt%~20wt%.

[0032] In one embodiment of the present invention, the mass ratio of ferric acid solution to aluminum ash is 3~3.5:1.

[0033] In this invention, the hydrochloric acid concentration in the ferric acid solution is controlled between 15wt% and 20wt% to achieve a better balance in the leaching rates of aluminum and iron. Too low an acid concentration will result in insufficient dissolution, while too high a concentration will increase hydrochloric acid volatilization losses and reduce effective utilization. Simultaneously, the ferric acid solution and aluminum ash are fed at a mass ratio of 3 to 3.5:1, ensuring sufficient contact and reaction of the reactants while avoiding waste of raw materials due to excessive aluminum ash.

[0034] The present invention will now be described in detail with reference to preferred embodiments and comparative examples. The preferred embodiments of the invention described below can be modified in various ways, and therefore the scope of the invention should not be construed as limited to the preferred embodiments described in detail below. Preferred embodiments are provided to help those skilled in the art to more readily understand the invention.

[0035] Example 1 A resource recovery process for iron-containing waste acid solution includes the following steps: S1. Place 500 mL of iron-containing waste acid solution (160 g / L ferrous ions and 10% hydrochloric acid by mass) in a three-necked flask, add 0.5 g of activated carbon powder and mix. Then, oxidize the ferrous ions by passing oxygen through at a flow rate of 1 L / min. Extract with 500 mL of composite extractant for 3 min, let stand, and separate into layers to obtain an iron-containing organic phase and a regenerated acid-containing aqueous phase. S2. The iron-containing organic phase is back-extracted with water at a volume ratio of 1:1 for 4 minutes, then allowed to stand and separate into layers to obtain iron-containing wastewater and regenerated organic phase. S3. Mix iron-containing wastewater with hydrochloric acid to prepare an iron-containing acid solution with a hydrochloric acid concentration of 15wt%. Mix the iron-containing acid solution with aluminum ash at a mass ratio of 3:1. Add aluminum ash to the iron-containing acid solution in batches. The first addition of aluminum ash is 40% of the total mass of aluminum ash, the second addition is 30% of the total mass of aluminum ash, and the third addition is 30% of the total mass of aluminum ash. After reacting at 85℃ for 150 min, a reaction solution is obtained. While stirring, add sodium fatty acid methyl ester sulfonate and polyacrylamide to the reaction solution (the mass ratio of reaction solution: sodium fatty acid methyl ester sulfonate: polyacrylamide is 1:0.7:0.3). After the addition is complete, stir evenly, let stand and separate into layers. The supernatant is polyaluminum ferric chloride. The composite extractant was prepared by the following method: 10 parts by weight of sulfonated kerosene, 5 parts by weight of trialkyl phosphorus oxide and 5 parts by weight of dimethylheptyl methylphosphonate were mixed evenly to obtain the composite extractant.

[0036] Example 2 A resource recovery process for iron-containing waste acid solution includes the following steps: S1. Place 500 mL of iron-containing waste acid solution (160 g / L ferrous ions and 10% hydrochloric acid by mass) in a three-necked flask, add 1 g of activated carbon powder and mix. Then, oxidize the ferrous ions by passing oxygen through at a flow rate of 1.5 L / min. Extract with 500 mL of composite extractant for 4 min, let stand, and separate into layers to obtain an iron-containing organic phase and a regenerated acid-containing aqueous phase. S2. The iron-containing organic phase is back-extracted with water at a volume ratio of 1:1 for 3.5 min, then allowed to stand and separate into layers to obtain iron-containing wastewater and regenerated organic phase. S3. Mix iron-containing wastewater with hydrochloric acid to prepare an iron-containing acid solution with a hydrochloric acid concentration of 20wt%. Mix the iron-containing acid solution with aluminum ash at a mass ratio of 3.5:1. Add aluminum ash to the iron-containing acid solution in batches. The first addition of aluminum ash is 40% of the total mass of aluminum ash, the second addition is 30% of the total mass of aluminum ash, and the third addition is 30% of the total mass of aluminum ash. After reacting at 90℃ for 130 minutes, a reaction solution is obtained. While stirring, add sodium fatty acid methyl ester sulfonate and polyacrylamide to the reaction solution (the mass ratio of reaction solution: sodium fatty acid methyl ester sulfonate: polyacrylamide is 1:0.7:0.3). After the addition is complete, stir evenly, let stand and separate into layers. The supernatant is polyaluminum ferric chloride. The composite extractant was prepared by the following method: 10 parts by weight of sulfonated kerosene, 2.5 parts by weight of trialkyl phosphorus oxide and 2.5 parts by weight of dibutyl phosphate were mixed evenly to obtain the composite extractant.

[0037] Example 3 The only difference from Example 1 is: The composite extractant was prepared by the following method: 10 parts by weight of sulfonated kerosene, 4 parts by weight of trialkyl phosphorus oxide and 6 parts by weight of dimethylheptyl methylphosphonate were mixed evenly to obtain the composite extractant.

[0038] Example 4 The only difference from Example 1 is: The composite extractant was prepared by the following method: 10 parts by weight of sulfonated kerosene, 3 parts by weight of trialkyl phosphorus oxide and 7 parts by weight of dimethylheptyl methylphosphonate were mixed evenly to obtain the composite extractant.

[0039] Example 5 The only difference from Example 1 is: The composite extractant was prepared by the following method: 10 parts by weight of sulfonated kerosene, 1.25 parts by weight of trialkyl phosphorus oxide and 8.75 parts by weight of dimethylheptyl methylphosphonate were mixed evenly to obtain the composite extractant.

[0040] Comparative Example 1 The only difference from Example 1 is that trialkylphosphine oxide is replaced with an equal amount of dimethylheptyl methylphosphonate.

[0041] Comparative Example 2 The only difference from Example 1 is that dimethylheptyl methylphosphonate is replaced with an equal amount of trialkylphosphine oxide.

[0042] Comparative Example 3 The only difference from Example 1 is that dimethylheptyl methylphosphonate is replaced with an equal amount of tributyl phosphate.

[0043] Comparative Example 4 The only difference from Example 1 is that dimethylheptyl methylphosphonate is replaced with an equal amount of 2-ethylhexyl phosphate mono-2-ethylhexyl ester.

[0044] Performance testing: (1) Iron removal rate: The iron content in the iron-containing waste acid solution and the iron content in the regenerated acid-containing aqueous phase were tested respectively, and the iron removal rate was calculated according to the following formula: Iron removal rate (%) = (Iron content in iron-containing waste acid solution - Iron content in regenerated acid-containing aqueous phase) ÷ Iron content in iron-containing waste acid solution × 100%; (2) Purity of polyaluminum ferric chloride; the results are recorded in Table 1.

[0045] Table 1. Test results of iron removal rate and polyaluminum ferric chloride purity

[0046] Compared with Comparative Examples 1-4, Examples 1-5 showed higher iron removal rates and higher polyaluminum ferric chloride purity, indicating that compared with trialkyl phosphate and monoalkyl phosphate, the use of dialkyl alkyl phosphonate in combination with trialkyl phosphorus oxide and diluent can improve the separation effect of iron and acid, thereby improving the iron removal rate and the purity of polyaluminum ferric chloride.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the resource recovery of an iron-containing spent acid solution, characterized in that, Includes the following steps: S1. After oxidizing ferrous ions in the iron-containing waste acid solution to ferric ions, the solution is extracted with a composite extractant to obtain an iron-containing organic phase and a regenerated acid-containing aqueous phase. S2. The iron-containing organic phase is back-extracted with water to obtain iron-containing wastewater and a regenerated organic phase; S3. Use the iron-containing wastewater to prepare iron-containing compounds; The composite extractant includes a diluent, trialkyl phosphorus oxide, and dialkyl alkyl phosphonate.

2. A process for the resource recovery of a ferrous spent acid solution according to claim 1, characterized in that, The mass ratio of the trialkyl phosphorus oxide and the dialkyl alkyl phosphonate to the diluent is 0.5~1:

1.

3. The resource utilization treatment process for iron-containing waste acid solution according to claim 1, characterized in that, The mass ratio of the trialkyl phosphorus oxide to the alkylphosphonic acid dialkyl ester is 2:3 to 3:

7.

4. The resource utilization treatment process for iron-containing waste acid solution according to claim 1, characterized in that, The diluent is sulfonated kerosene.

5. The resource utilization treatment process for iron-containing waste acid solution according to claim 1, characterized in that, The alkylphosphonate dialkyl ester includes one or both of dimethylheptyl methylphosphonate and dibutyl butyl phosphate.

6. The resource utilization treatment process for iron-containing waste acid solution according to claim 1, characterized in that, The process of oxidizing ferrous ions in an iron-containing waste acid solution to ferric ions includes the following steps: mixing the iron-containing waste acid solution with activated carbon powder, and oxidizing the ferrous ions to ferric ions in an oxygen atmosphere.

7. The resource utilization treatment process for iron-containing waste acid solution according to claim 6, characterized in that, The mass-to-volume ratio of activated carbon powder to iron-containing waste acid solution is 0.5~1g:500mL.

8. The resource recovery process for iron-containing waste acid solution according to claim 1, characterized in that, Step S3 includes the following steps: mixing the iron-containing wastewater with hydrochloric acid to obtain an iron-containing acid solution; mixing the iron-containing acid solution with aluminum ash at 85~90℃ to react; after the reaction is completed, adding sodium fatty acid methyl ester sulfonate and polyacrylamide, stirring and allowing it to stand to separate into layers, the supernatant is polyaluminum ferric chloride.

9. The resource utilization treatment process for iron-containing waste acid solution according to claim 8, characterized in that, The concentration of hydrochloric acid in the iron-containing acid solution is 15wt%~20wt%.

10. The resource utilization treatment process for iron-containing waste acid solution according to claim 8, characterized in that, The mass ratio of the ferric acid solution to the aluminum ash is 3~3.5:1.

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