Resourceful treatment method for sulfuric acid-containing wastewater

Abstract

The invention provides a resourceful treatment method for sulfuric acid-containing wastewater, and belongs to the technical field of hydrometallurgy. The method comprises the following steps: mixing the sulfuric acid-containing wastewater with an organic solution, extracting, and standing for phase splitting to obtain a loaded organic phase and raffinate wastewater; mixing the loaded organic phase with an ammonia stripping agent, extracting, and standing for phase splitting to obtain stripping liquid ammonium sulfate and a stripped organic phase; and mixing the reverse-extracted organic phase with water, extracting, and standing for phase splitting to obtain a washed organic phase and a washing solution. According to the method, sulfuric acid in the sulfuric acid-containing wastewater is extracted by adopting an amine extraction agent, reverse extraction is carried out by using an ammonia reverse extraction agent, an ammonium sulfate solution with relatively high concentration is finally recovered, and raffinate after extraction is reused for a front-end process water link. Compared with an existing lime direct neutralization method, high-value recycling of resources is achieved, and no solid waste is generated.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a resource treatment method for sulfuric acid-containing wastewater. Background Art

[0002] Sulfuric acid wastewater has scattered sources, large output, and high difficulty in treatment. It is mostly produced in the production of titanium dioxide, dyes, petroleum, chemical fibers, etc., so there are great differences in the sources and quantities of output. The investment in the treatment and recovery of sulfuric acid wastewater is also different. Usually, sulfuric acid wastewater contains certain organic matter, metal ions and other impurities, and the treatment process is complicated and difficult. If it is discharged without treatment or incomplete treatment, it will cause extremely serious pollution to the surrounding ecological environment.

[0003] In view of the treatment of wastewater containing sulfuric acid, a variety of waste sulfuric acid recovery and utilization technologies have been developed and researched, which have effectively improved the utilization rate of waste sulfuric acid. Among them, the diffusion dialysis method has been studied more, but the acid recovery rate and concentration are low and it still contains a certain amount of impurities such as ferrous sulfate, which limits the direct utilization or further concentration of recovered sulfuric acid. In industry, there is also a method of direct neutralization with lime to produce a large amount of calcium sulfate mixed with other substances, which is stored as solid waste. Although the process is simple and the treatment cost is low, the generation of a large amount of solid waste causes waste of resources, increases storage and transportation costs, and has an adverse impact on the environment. Therefore, it is particularly important to develop a resource-based treatment process for sulfuric acid-containing wastewater. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for resource recovery treatment of sulfuric acid-containing wastewater.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for recycling sulfuric acid-containing wastewater comprises the following steps:

[0007] (1) Extraction stage: The sulfuric acid-containing wastewater is mixed with an organic solution and then extracted, and then allowed to stand for phase separation to obtain a loaded organic phase and raffinate wastewater;

[0008] (2) Stripping stage: the loaded organic phase is mixed with an ammonia stripping agent and then extracted, and the mixture is allowed to stand for phase separation to obtain a stripping solution of ammonium sulfate and an organic phase after stripping;

[0009] (3) Water washing stage: the organic phase after stripping is mixed with water and then extracted, and allowed to stand for phase separation to obtain a washed organic phase and a washing liquid;

[0010] The organic solution is composed of an extractant, an additive and a diluent;

[0011] The extractant is at least one of N1923, trioctylamine and triisooctylamine;

[0012] The additive is n-octanol and / or isooctyl alcohol;

[0013] The diluent is white oil.

[0014] In the present invention, the addition of additives is beneficial to increasing the phase separation rate of the two phases during stripping and reducing the occurrence of emulsification during stripping; the addition of diluent is beneficial to the phase separation of the two phases.

[0015] In some embodiments of the present invention, the content of the extractant in the organic solution is 20-45% v / v, the content of the additive is 0%-40% v / v, and the content of the diluent is 15%-80% v / v. In the present invention, if the content of the extractant is too high, subsequent organic phase separation will be difficult.

[0016] In some embodiments of the present invention, the content of the extractant in the organic solution is 40-45% v / v, the content of the additive is 0, and the content of the diluent is 55%-60% v / v.

[0017] In some embodiments of the present invention, the content of the extractant in the organic solution is 20-45% v / v, the content of the additive is 5-10% v / v, and the content of the diluent is 45%-75% v / v.

[0018] In some embodiments of the present invention, H + The molar concentration is 0.2-1 mol / L; the volume ratio of the organic solution to the sulfuric acid-containing wastewater is 1:1-1:6; when the sulfuric acid-containing wastewater is mixed with the organic solution and then extracted, the temperature of the extraction system is 20-50°C.

[0019] In some embodiments of the present invention, the ammonia stripping agent is at least one of ammonia water, ammonium bicarbonate and ammonium carbonate; the ammonia stripping agent contains NH4 + The concentration is 1mol / L-4mol / L. In the present invention, if the stripping agent contains NH4 + If the concentration is too low, the ammonium sulfate concentration in the stripping solution will be low, which will result in high energy consumption for evaporation and crystallization.

[0020] In some embodiments of the present invention, the volume ratio of the loaded organic phase to the ammonia stripping agent is 1:1-4:1.

[0021] In some embodiments of the present invention, when the loaded organic phase is mixed with an ammonia stripping agent for extraction, the temperature of the extraction system is 20-50° C. In the present invention, if the temperature is too low, it is not conducive to phase separation, and if the temperature is too high, the organic phase will be easily volatile and cause organic loss.

[0022] In the present invention, after stripping, the raffinate wastewater can be reused.

[0023] In some embodiments of the present invention, the volume ratio of the organic phase to water after stripping is 1:1-1:3.

[0024] In some embodiments of the present invention, when the stripping organic phase is mixed with water for extraction, the temperature of the extraction system is 20-50° C. In the present invention, the washed organic phase can be reused, and the washing liquid is used to prepare the stripping agent in step (2).

[0025] In the present invention, the extraction section, stripping section and water washing section are all continuous stage reactions.

[0026] The present invention discloses the following technical effects:

[0027] (1) Compared with the traditional lime direct precipitation treatment method, the present invention does not generate solid waste, and sulfate ions are recovered in the form of ammonium sulfate, thereby achieving high-value recovery of resources.

[0028] (2) The ammonium sulfate solution recovered by this method has a higher concentration, which reduces the subsequent evaporation and crystallization cost.

[0029] (3) The organic extractant used in this method can be recycled and only needs to be invested once. DETAILED DESCRIPTION

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0032] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0033] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0034] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0035] The present invention uses an amine extractant to extract sulfuric acid from sulfuric acid-containing wastewater, uses an ammonia stripping agent for stripping, and finally recovers a relatively high concentration of ammonium sulfate solution. After evaporation and crystallization, a high-value ammonium sulfate byproduct is recovered, and the raffinate after extraction is reused in the front-end process water link. Compared with the existing lime direct neutralization method, it realizes high-value resource recovery without generating solid waste.

[0036] Specifically, the resource treatment method of sulfuric acid-containing wastewater of the present invention comprises the following steps:

[0037] First, the sulfuric acid-containing wastewater is mixed with an organic solution and then extracted, wherein the organic solution is composed of an extractant, an additive and a diluent, wherein the extractant is N1923, at least one of trioctylamine and triisooctylamine, the additive is n-octanol and / or isooctyl alcohol, and the diluent is white oil, wherein the content of the extractant in the organic solution is 20-45% v / v, the content of the additive is 0%-40% v / v, and the content of the diluent is 15%-80% v / v. The volume ratio of the organic solution to the sulfuric acid-containing wastewater is 1:1-1:6, and the temperature of the extraction system during extraction is 20-50°C. Then, the phases are allowed to stand and separated to obtain a loaded organic phase and a residual wastewater. The loaded organic phase is mixed with an ammonia stripping agent and then extracted, wherein the ammonia stripping agent is at least one of ammonia water, ammonium bicarbonate and ammonium carbonate, wherein the stripping agent contains NH4 + The concentration is 1mol / L-4mol / L; the volume ratio of the loaded organic to the ammonia stripping agent is 1:1-4:1, and the temperature of the extraction system during extraction is 20-50°C. After that, the stripping liquid ammonium sulfate and the organic phase after stripping are obtained by standing and separating, and the residual wastewater is reused; the organic phase after stripping is mixed with water for washing, and the volume ratio of the organic phase after stripping to water is 1:1-1:3, and the temperature is 20-50°C. After mixing, the organic phase after washing and the washing liquid are obtained by standing and separating, and the organic phase after washing is reused, and the washing liquid is used to prepare the stripping agent.

[0038] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0039] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] First, sulfuric acid wastewater (H + The organic solution (1mol / L) is mixed with an organic solution (the organic solution is composed of 45% v / v N1923, 40% v / v isooctyl alcohol and 15% v / v white oil) for extraction. The volume ratio of the organic solution to the sulfuric acid-containing wastewater is 1:6. The temperature of the extraction system is 50°C during extraction. After standing and separating, the loaded organic phase and the raffinate wastewater are obtained. The extraction section is a continuous 3-stage reaction. The loaded organic phase is mixed with an ammonia stripping agent for extraction, wherein the ammonia stripping agent is ammonia water, NH4 + The concentration is 4mol / L; the volume ratio of the loaded organic to the ammonia stripping agent is 1:1. The temperature of the extraction system during extraction is 50°C. After that, the stripping solution ammonium sulfate and the organic phase after stripping are obtained by standing and separating. The concentration of ammonium sulfate in the stripping solution is 300g / L. The residual wastewater is reused. The stripping section is a continuous 5-stage reaction. The organic phase after stripping is mixed with water for washing. The volume ratio of the organic phase after stripping to water is 1:3, and the temperature is 50°C. After mixing, the organic phase after washing and the washing liquid are obtained by standing and separating. The organic phase after washing is reused. The washing liquid is used to prepare the stripping agent. The water washing section is a continuous 5-stage reaction.

[0042] Example 2

[0043] First, sulfuric acid wastewater (H + The organic solution is 0.2mol / L) and then mixed with an organic solution (the organic solution is composed of 20% v / v tri-isooctylamine, 5% v / v n-octanol and 75% v / v white oil) for extraction. The volume ratio of the organic solution to the sulfuric acid-containing wastewater is 1:1. The temperature of the extraction system during extraction is 50°C. After that, the phases are allowed to stand and separate to obtain the loaded organic phase and the raffinate wastewater. The extraction section is a continuous 3-stage reaction. The loaded organic phase is mixed with an ammonia stripping agent for extraction, wherein the ammonia stripping agent is ammonia water, NH4 + The concentration is 1mol / L; the volume ratio of the loaded organic to the ammonia stripping agent is 4:1. The temperature of the extraction system during extraction is 50°C. After that, the stripping solution ammonium sulfate and the stripping organic phase are obtained by standing and separating. The stripping solution ammonium sulfate concentration is 70g / L. The residual wastewater is reused. The stripping section is a continuous 5-stage reaction. The stripping organic phase is mixed with water for washing. The volume ratio of the stripping organic phase to water is 1:1, and the temperature is 50°C. After mixing, the organic phase is allowed to stand and separate to obtain the washed organic phase and the washing liquid. The washed organic phase is reused. The washing liquid is used to prepare the stripping agent. The water washing section is a continuous 2-stage reaction.

[0044] Example 3

[0045] First, sulfuric acid wastewater (H +The organic solution (0.5mol / L) was mixed with an organic solution (the organic solution was composed of 40% v / v N1923 and 60% v / v white oil) for extraction. The volume ratio of the organic solution to the sulfuric acid-containing wastewater was 1:5. The temperature of the extraction system was 20°C. After that, the phases were allowed to stand for separation to obtain the loaded organic phase and the raffinate wastewater. The extraction stage was a continuous 5-stage reaction. The loaded organic phase was mixed with an ammonia stripping agent for extraction, wherein the ammonia stripping agent was ammonium bicarbonate, NH4 + The concentration is 3mol / L; the volume ratio of the loaded organic to the ammonia stripping agent is 1:1. The temperature of the extraction system during extraction is 20°C. After that, the stripping solution ammonium sulfate and the organic phase after stripping are obtained by standing and separation. The concentration of ammonium sulfate in the stripping solution is 200g / L. The residual wastewater is reused. The stripping section is a continuous 3-stage reaction. The organic phase after stripping is mixed with water for washing. The volume ratio of the organic phase after stripping to water is 1:1, and the temperature is 20°C. After mixing, the organic phase after washing and the washing liquid are obtained by standing and separation. The organic phase after washing is reused. The washing liquid is used to prepare the stripping agent. The water washing section is a continuous 2-stage reaction.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recycling sulfuric acid-containing wastewater, characterized in that: The following steps are involved: (1) Extraction stage: The sulfuric acid-containing wastewater is mixed with an organic solution and then extracted, and then allowed to stand for phase separation to obtain a loaded organic phase and raffinate wastewater; (2) Stripping stage: the loaded organic phase is mixed with an ammonia stripping agent and then extracted, and the mixture is allowed to stand for phase separation to obtain a stripping solution of ammonium sulfate and an organic phase after stripping; (3) Water washing stage: the organic phase after stripping is mixed with water and then extracted, and allowed to stand for phase separation to obtain a washed organic phase and a washing liquid; The organic solution is composed of an extractant, an additive and a diluent; The extractant is at least one of N1923, trioctylamine and triisooctylamine; The additive is n-octanol and / or isooctyl alcohol; The diluent is white oil.

2. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: The content of the extractant in the organic solution is 20-45% v / v, the content of the additive is 0%-40% v / v, and the content of the diluent is 15%-80% v / v.

3. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: The H + The molar concentration is 0.2-1 mol / L; the volume ratio of the organic solution to the sulfuric acid-containing wastewater is 1:1-1:6; when the sulfuric acid-containing wastewater is mixed with the organic solution and then extracted, the temperature of the extraction system is 20-50°C.

4. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: The ammonia stripping agent is at least one of ammonia water, ammonium bicarbonate and ammonium carbonate; the ammonia stripping agent contains NH4 + The concentration is 1mol / L-4mol / L.

5. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: The volume ratio of the loaded organic phase to the ammonia stripping agent is 1:1-4:

1.

6. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: When the loaded organic phase is mixed with an ammonia stripping agent and then extracted, the temperature of the extraction system is 20-50°C.

7. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: The volume ratio of the organic phase to water after the stripping is 1:1-1:

3.

8. The method for recycling sulfuric acid-containing wastewater according to claim 1, characterized in that: When the organic phase after stripping is mixed with water for extraction, the temperature of the extraction system is 20-50°C.