Vanadium-containing wastewater recovery method

Abstract

The invention relates to the technical field of chemical production, and provides a vanadium-containing wastewater recycling method which comprises the following steps: adding limestone powder into vanadium-containing wastewater to obtain alkaline slurry with the pH value of more than 10; mixing the alkaline slurry with the acidic vanadium extraction slurry generated in the main production process section, and carrying out a neutralization reaction; the mixed slurry obtained after the neutralization reaction is filtered, and acidic vanadium-containing filtrate and primary vanadium-containing tailings are obtained; the obtained alkaline slurry is used for washing primary vanadium-containing tailings, washing filtrate is mixed with the obtained acidic vanadium-containing filtrate, and weakly acidic vanadium-containing filtrate and final vanadium-containing tailings are obtained; and the weak-acid vanadium-containing filtrate is returned to the main production process section for recycling, and final vanadium-containing tailings are subjected to secondary recovery treatment to achieve vanadium resource recovery. According to the scheme, the problems of resource waste, acid-base double consumption and solid waste pollution are solved, and high efficiency and cleanness of vanadium-containing wastewater treatment are achieved.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, and in particular to a method for recovering vanadium-containing wastewater. Background Technology

[0002] In the field of clean production of vanadium oxide, the current mainstream process uses the calcination-roasting-sulfuric acid leaching method to treat vanadium slag. The resulting vanadium solution is then subjected to acid precipitation to produce ammonium polyvanadate and acidic vanadium-containing wastewater.

[0003] Existing technologies for treating acidic vanadium-containing wastewater involve adding activated lime powder to the wastewater for neutralization, producing alkaline reclaimed water and vanadium-containing wastewater treatment sludge cake. The alkaline reclaimed water requires additional acid to adjust its pH before being recycled back into the production system; however, the vanadium-containing wastewater treatment sludge cake is directly discharged as general industrial solid waste. This method has at least the following drawbacks: Firstly, while the vanadium-containing wastewater treatment sludge cake has a high vanadium content, the vanadium is encapsulated by impurities such as gypsum, making economic recovery impossible and resulting in significant resource waste. Secondly, the alkaline reclaimed water requires purchased acid to adjust the pH, while the upstream acidic vanadium extraction slurry requires purchased alkali for neutralization, increasing production costs due to the dual consumption of reagents.

[0004] Therefore, there is an urgent need for an innovative method for recycling vanadium-containing wastewater that eliminates solid waste at its source and achieves a balance of endogenous materials. Summary of the Invention

[0005] Existing methods for treating vanadium-containing wastewater suffer from resource waste and increased production costs due to dual-use reagent consumption. This disclosure provides a method for recovering vanadium-containing wastewater, comprising: Step a: Add limestone powder to vanadium-containing wastewater to obtain an alkaline slurry with a pH value > 10; Step b: Mix the alkaline slurry with the acidic vanadium extraction slurry produced in the main production process section to carry out a neutralization reaction; Step c: Filter the mixed slurry after neutralization reaction to obtain acidic vanadium-containing filtrate and primary vanadium-containing tailings; Step d: Wash the primary vanadium-containing tailings with the alkaline slurry obtained in step a, and mix the washing filtrate with the acidic vanadium-containing filtrate obtained in step c to obtain a weakly acidic vanadium-containing filtrate and the final vanadium-containing tailings. Step e: Return the weakly acidic vanadium-containing filtrate to the main production process section for recycling, and perform secondary recycling treatment on the final vanadium-containing tailings to achieve vanadium resource recovery.

[0006] In some embodiments, step a includes: performing enhanced aeration while treating with the limestone powder.

[0007] In some embodiments, the aeration intensity of the enhanced aeration treatment in step a is 0.8-1.5 m. 3 / (m 2 (min), the aeration time is 30-60 minutes.

[0008] In some embodiments, step b includes: dynamically adjusting the flow ratio of the alkaline slurry to the acidic vanadium extraction slurry by real-time monitoring of the pH value of the neutralization reaction mixture.

[0009] In some embodiments, step b includes controlling the endpoint pH of the neutralization reaction to be 2-3.

[0010] In some embodiments, step d includes: using a portion or all of the alkaline slurry obtained in step a as a washing slurry to wash the primary vanadium-containing tailings, followed by solid-liquid separation to obtain a washing filtrate.

[0011] In some embodiments, step d further includes using 25%-40% of the total amount of the alkaline slurry obtained in step a as a washing slurry.

[0012] In some embodiments, the pH value of the weakly acidic vanadium-containing filtrate obtained in step d is 2.5-3.5.

[0013] In some embodiments, in step d, the washing method for the primary vanadium-containing tailings is one or more countercurrent washing methods.

[0014] In some embodiments, step e includes: returning the weakly acidic vanadium-containing filtrate to the leaching process of the main production process section for recycling.

[0015] The aforementioned method for recovering vanadium-containing wastewater directly mixes the alkaline slurry generated from the vanadium-containing wastewater treatment process with the acidic vanadium extraction slurry generated from the main production process. This eliminates the generation of vanadium-containing wastewater treatment sludge cake at the source, thereby reducing the waste of vanadium pentoxide resources. The vanadium-containing tailings are recovered as high-grade vanadium resources, improving the overall vanadium recovery rate. The alkaline slurry directly neutralizes the acidic vanadium extraction slurry, simultaneously eliminating the need for dual external purchases of acid for alkaline reclaimed water recycling and alkali for neutralizing acidic slurries, significantly reducing production costs. Furthermore, the neutral vanadium-containing filtrate can be directly recycled without external wastewater discharge, mitigating the risk of secondary pollution from traditional processes. This invention's method for recovering vanadium-containing wastewater, through process restructuring and internal material recycling, solves the problems of resource waste, dual acid and alkali consumption, and solid waste pollution, facilitating the efficient and clean treatment of vanadium-containing wastewater. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating a method for recovering vanadium-containing wastewater according to an embodiment of the present invention; Figure 2 A comparison chart showing the process optimization before and after optimization of the method for recovering vanadium-containing wastewater. Detailed Implementation

[0018] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0019] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0020] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Terms such as "including" or "contains" mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility of covering other elements as well.

[0021] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0022] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0023] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0024] Please refer to Figure 1 , Figure 1 The flowchart shown illustrates a method for recovering vanadium-containing wastewater according to an embodiment of the present invention. The method for recovering vanadium-containing wastewater shown in this embodiment includes: Step a: Add vanadium-containing wastewater to limestone powder to obtain an alkaline slurry with a pH value > 10.

[0025] The alkaline slurry is an alkaline liquid product obtained by adding vanadium-containing wastewater to neutralize it and then treating it through a precipitation process. In the precipitation process, some suspended particles and colloidal substances in the wastewater will precipitate. After solid-liquid separation, the liquid product obtained is the alkaline slurry, and its pH value is usually between 11 and 12.

[0026] In one specific embodiment, step a further includes dynamically adjusting the flow ratio of the alkaline slurry to the acidic vanadium extraction slurry by real-time monitoring of the pH value of the neutralization reaction mixture. Specifically, an online pH monitor can be used to monitor the pH value of the mixture in real time, and the monitored pH value signal is transmitted to the control system. The control system automatically adjusts the flow rates of the delivery pumps for the alkaline slurry and the acidic vanadium extraction slurry according to the set pH value range, thereby achieving dynamic adjustment of the flow ratio between the two.

[0027] Step b: Mix the alkaline slurry with the acidic vanadium extraction slurry produced in the main production process section to carry out a neutralization reaction.

[0028] The main production process segment refers to the core production flow from vanadium ore raw materials to vanadium products (such as vanadium pentoxide). This segment generates acidic vanadium extraction slurry and is also the main site for the recycling of neutral vanadium-containing filtrate. Its typical process includes the following key steps: vanadium ore crushing and ball milling, vanadium slag leaching (the source of acidic vanadium extraction slurry), purification and separation, vanadium product preparation, and recycling. The acidic vanadium extraction slurry generated in the main production process segment is produced during vanadium extraction. During the neutralization reaction, alkaline slurry and acidic vanadium extraction slurry are introduced into the reaction vessel in a certain proportion and thoroughly mixed by stirring.

[0029] In one specific embodiment, step b further includes controlling the endpoint pH of the neutralization reaction to be 2-3. This is because within this pH range, vanadium ions can react more readily with other substances, which is beneficial for subsequent separation and recovery.

[0030] Step c: Filter the mixed slurry after the neutralization reaction to obtain acidic vanadium-containing filtrate and primary vanadium-containing tailings.

[0031] The neutralized slurry mixture is pumped into a solid-liquid separation device, such as a box filter press, belt filter, or centrifuge. Under pressure or centrifugal force, the liquid (filtrate) passes through the filter medium, while solid particles are trapped to form a filter cake. At this point, most of the vanadium has been enriched in the primary vanadium-containing tailings, but a large amount of vanadium-containing mother liquor is still adsorbed in the pores of the filter cake. Directly discarding it would result in a loss of vanadium.

[0032] Step d: Wash the primary vanadium-containing tailings with the alkaline slurry obtained in step a, and mix the washing filtrate with the acidic vanadium-containing filtrate obtained in step c to obtain a weakly acidic vanadium-containing filtrate and the final vanadium-containing tailings.

[0033] In this process, another portion of the alkaline slurry prepared in step a is used as a washing liquid and sprayed onto the filter cake of the primary vanadium-containing tailings produced in step c. The washing liquid penetrates the filter cake, displacing the highly acidic, high-vanadium-concentration mother liquor adsorbed in the pores to form a washing filtrate. This washing filtrate is then mixed with the acidic vanadium-containing filtrate produced in step c in a collection tank. The vanadium content of the washed solid is further reduced, becoming the final vanadium-containing tailings. Step d involves purifying and recovering the solid residue separated in step c, which is crucial for improving the vanadium recovery rate.

[0034] Step e: Return the weakly acidic vanadium-containing filtrate to the main production process section for recycling, and perform secondary recycling treatment on the final vanadium-containing tailings to achieve vanadium resource recovery.

[0035] In step d, the weakly acidic vanadium-containing filtrate, with optimized composition and pH, is directly returned to the leaching or extraction processes of the main production process via a pumping system for reuse as process water or acid replenishment medium. The final vanadium-containing tailings are collected and sent to a dedicated vanadium extraction system (such as a roasting-leaching unit) for secondary treatment. Step e achieves a closed-loop resource recycling and final treatment.

[0036] The pH value of the weakly acidic vanadium-containing filtrate obtained in step d is 2.5-3.5.

[0037] In some embodiments, step e includes: returning the weakly acidic vanadium-containing filtrate to the leaching process of the main production stage for recycling. For the secondary recovery treatment of vanadium-containing tailings, the vanadium-containing tailings are leached with sulfuric acid solution to obtain vanadium-containing leachate; vanadium pentoxide is precipitated and recovered from the vanadium-containing leachate to achieve vanadium resource recovery. For example, during the leaching process, the concentration of sulfuric acid solution is usually controlled at 10-20%, the leaching temperature is 50-65℃, and the leaching time is 1-2 hours. By controlling these parameters, vanadium in the vanadium-containing tailings can be fully dissolved in the sulfuric acid solution to obtain vanadium-containing leachate. When precipitating and recovering vanadium pentoxide from the vanadium-containing leachate, a precipitant such as ammonia can be added to adjust the pH of the solution to 8-9, so that vanadium ions form ammonium vanadate precipitate. Then, the precipitate is filtered, washed, dried, calcined, etc., to obtain vanadium pentoxide product.

[0038] The comparison diagram before and after process optimization of the above-mentioned method for recovering vanadium-containing wastewater is shown in the figure below. Figure 2 As shown, this application directly mixes the alkaline slurry generated from the vanadium-containing wastewater treatment process with the acidic vanadium extraction slurry generated from the main production process, eliminating the generation of vanadium-containing wastewater treatment sludge cake at the source, thereby reducing the waste of vanadium pentoxide resources. The vanadium-containing tailings are recovered as high-grade vanadium resources, improving the overall vanadium recovery rate. By directly neutralizing the acidic vanadium extraction slurry with the alkaline slurry, the dual external purchase requirements for acid for alkaline reclaimed water recycling and alkali for neutralization of acidic slurry are simultaneously eliminated, significantly reducing production costs. At the same time, the neutral vanadium-containing filtrate can be directly recycled without external wastewater discharge, solving the risk of secondary pollution of water quality in traditional processes. This invention's method for recovering vanadium-containing wastewater solves the problems of resource waste, dual acid and alkali consumption, and solid waste pollution through process restructuring and internal material recycling, facilitating the efficient and clean treatment of vanadium-containing wastewater.

[0039] According to several embodiments of the present invention, step a includes: performing enhanced aeration while treating with limestone powder. By introducing enhanced aeration with specific parameters, the mass transfer efficiency of the gas-liquid-solid three-phase system is greatly enhanced during the neutralization process. The high-speed airflow not only provides sufficient stirring for the neutralization reaction, avoiding local supersaturation and scaling problems of limestone powder and ensuring reaction uniformity, but also effectively carries the CO2 gas generated during neutralization out of the system rapidly, accelerating the forward reaction, thereby significantly improving the neutralization reaction rate and the utilization rate of limestone powder.

[0040] According to several embodiments of the present invention, the aeration intensity of the enhanced aeration treatment in step a is 0.8-1.5 m. 3 / (m 2 The aeration time is 30-60 minutes. In one specific embodiment, limestone powder is used to neutralize the acidic vanadium extraction slurry while simultaneously enhancing aeration. The aeration intensity is controlled at 1.2 m / s. 3 / (m 2 (·min), the aeration time is 45 minutes.

[0041] According to several embodiments of the present invention, step b includes: dynamically adjusting the flow ratio of alkaline slurry to acidic vanadium extraction slurry by real-time monitoring of the pH value of the neutralization reaction mixture. In one specific embodiment, through real-time monitoring and dynamic feedback adjustment, precise automated control of the neutralization reaction process is achieved, completely changing the traditional method that relies on manual experience and has control lag. By monitoring the pH value in real time and dynamically adjusting the flow ratio of the two slurries, the neutralization reaction process can be precisely controlled, avoiding excessive pH fluctuations caused by slurry imbalance. This not only ensures the stability and sufficiency of the neutralization reaction but also reduces the load on subsequent processing steps, improves the reliability and efficiency of the entire recovery process, and reduces the risk of resource waste and equipment damage caused by reaction runaway.

[0042] According to several embodiments of the present invention, step b includes controlling the endpoint pH value of the neutralization reaction to be 2-3. Precisely controlling the endpoint pH within the optimal range (2-3) ensures that valuable metals such as vanadium precipitate into the slag in the most suitable form, laying a solid foundation for subsequent efficient separation and vanadium enrichment and recovery, and greatly improving the stability of process parameters and product consistency.

[0043] According to several embodiments of the present invention, step d includes: using part or all of the alkaline slurry obtained in step a as a washing slurry to wash the primary vanadium-containing tailings, followed by solid-liquid separation to obtain a washing filtrate. By utilizing the neutralized slurry, which is rich in lime and has a certain alkalinity, as a washing agent, no additional consumption of fresh chemical agents or clean water is required, achieving resource recycling of waste and significantly reducing operating costs and fresh water consumption.

[0044] According to several embodiments of the present invention, step d further includes: using 25%-40% of the total amount of alkaline slurry obtained in step a as washing slurry. In one specific embodiment, all the alkaline slurry obtained after neutralization in step a (or 30% of its total amount) is used as washing slurry, and the primary vanadium-containing tailings generated in step c are washed twice by countercurrent washing, followed by pressure filtration to obtain a weakly acidic vanadium-containing filtrate with a pH of 3.0.

[0045] According to several embodiments of the present invention, the pH value of the weakly acidic vanadium-containing filtrate obtained in step d is 2.5-3.5.

[0046] According to several embodiments of the present invention, in step d, the primary vanadium-containing tailings are washed using a single or multiple countercurrent washing method. Countercurrent washing achieves reverse contact between the washing water and the vanadium-containing tailings, obtaining the highest vanadium washing efficiency with the minimum amount of washing liquid, effectively reducing entrainment losses in the tailings, and thus significantly improving the overall vanadium recovery rate. By controlling the amount and method of washing liquid, the final washing filtrate has a stable pH in the weakly acidic range of 2.5-3.5 (e.g., 3.0). This pH condition is very suitable for direct return to the main process, avoiding a severe impact on the pH of the main process solution system after return, and creating the necessary conditions for subsequent recycling.

[0047] According to several embodiments of the present invention, step e includes: returning the weakly acidic vanadium-containing filtrate to the leaching process of the main production stage for recycling. In one specific embodiment, all the weakly acidic vanadium-containing filtrate with a pH of 3.0 obtained in step d is collected and pumped back to the leaching process of the main production stage for use as a makeup solution or preparation solution. Recycling the vanadium-containing filtrate to the vanadium slag leaching process of the main production stage achieves water resource recycling and reduces the consumption of fresh water. Simultaneously, the vanadium remaining in the filtrate can be recovered again in the leaching process, improving the overall vanadium recovery rate, reducing waste, and conforming to the concept of a circular economy.

[0048] In summary, this application presents a method for recovering vanadium-containing wastewater. By mixing and neutralizing alkaline slurry with acidic vanadium extraction slurry, the resource-efficient synergistic treatment of the two slurries is achieved. The neutralization reaction reduces the additional consumption of acid and alkali reagents, lowering treatment costs. The vanadium-containing filtrate obtained from solid-liquid separation is recycled to the main production process, improving the utilization rate of water and vanadium resources. The secondary recovery of vanadium-containing tailings further enhances the vanadium recovery rate, reduces resource waste and environmental pollution, and achieves a virtuous cycle of waste-to-waste treatment.

[0049] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0050] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A method for recovering vanadium-containing wastewater, characterized in that, include: Step a: Add limestone powder to vanadium-containing wastewater to obtain an alkaline slurry with a pH value > 10; Step b: Mix the alkaline slurry with the acidic vanadium extraction slurry produced in the main production process section to carry out a neutralization reaction; Step c: Filter the mixed slurry after neutralization reaction to obtain acidic vanadium-containing filtrate and primary vanadium-containing tailings; Step d: Wash the primary vanadium-containing tailings with the alkaline slurry obtained in step a, and mix the washing filtrate with the acidic vanadium-containing filtrate obtained in step c to obtain a weakly acidic vanadium-containing filtrate and the final vanadium-containing tailings. Step e: Return the weakly acidic vanadium-containing filtrate to the main production process section for recycling, and perform secondary recycling treatment on the final vanadium-containing tailings to achieve vanadium resource recovery.

2. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, Step a includes: performing enhanced aeration while treating with the limestone powder.

3. The method for recovering vanadium-containing wastewater according to claim 2, characterized in that, The aeration intensity of the enhanced aeration treatment in step a is 0.8-1.5 m. 3 / (m 2 (min), the aeration time is 30-60 minutes.

4. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, Step b includes: dynamically adjusting the flow ratio of the alkaline slurry to the acidic vanadium extraction slurry by real-time monitoring of the pH value of the neutralization reaction mixture.

5. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, Step b includes controlling the pH value at the endpoint of the neutralization reaction to be 2-3.

6. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, Step d includes: using part or all of the alkaline slurry obtained in step a as a washing slurry to wash the primary vanadium-containing tailings, followed by solid-liquid separation to obtain the washing filtrate.

7. The method for recovering vanadium-containing wastewater according to claim 6, characterized in that, Step d further includes using 25%-40% of the total amount of the alkaline slurry obtained in step a as a washing slurry.

8. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, The pH value of the weakly acidic vanadium-containing filtrate obtained in step d is 2.5-3.

5.

9. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, In step d, the primary vanadium-containing tailings are washed using a single or multiple countercurrent washing method.

10. The method for recovering vanadium-containing wastewater according to claim 1, characterized in that, Step e includes: returning the weakly acidic vanadium-containing filtrate to the leaching process of the main production process section for recycling.

Images