Iron phosphate wastewater evaporation treatment system and evaporation treatment method

Abstract

The invention provides an iron phosphate wastewater evaporation treatment system and an evaporation treatment method, and relates to the technical field of wastewater treatment. The system comprises an evaporation unit, a centrifugation unit and an oxidation sedimentation unit which are communicated in sequence, the evaporation unit is used for carrying out evaporation treatment on an iron phosphate wastewater concentrated solution to obtain a first treatment solution; the centrifugal unit is used for carrying out centrifugal treatment on the first treatment liquid to obtain second treatment liquid and ammonium sulfate salt crystals; the oxidation sedimentation unit comprises an oxidation subunit and a sedimentation subunit, the oxidation subunit is used for removing COD (Chemical Oxygen Demand) and / or chloride ions in the second treatment liquid to obtain a third treatment liquid, and the sedimentation subunit is used for neutralizing and settling the third treatment liquid to obtain ammonium sulfate bottom mud and a fourth treatment liquid; a communication pipeline is arranged between the oxidation subunit and the sedimentation subunit, a pipeline mixer is arranged on the communication pipeline, and the pipeline mixer is filled with a pH regulator. According to the system, COD and / or chloride ions in the waste liquid can be efficiently removed, and the quality of by-products is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to an evaporation treatment system and an evaporation treatment method for iron phosphate wastewater which can be used for removing impurities and controlling the quality of ammonium sulfate byproducts. Background Art

[0002] During the production process, ferric phosphate goes through synthesis, water washing and other processes. The synthetic mother liquor and washing water produced are high-salt inorganic wastewater containing metal ions, sulfate ions and phosphate ions at different concentrations. The COD in ferric phosphate wastewater is relatively high. Therefore, it is difficult to treat, and the discharge of wastewater will cause serious damage and impact on the surrounding environment.

[0003] At present, in the treatment process of ferric phosphate wastewater, an evaporation treatment system is often used to deeply treat the ferric phosphate wastewater. However, as the evaporation proceeds, the COD and impurity ions in the ferric phosphate wastewater will continue to be enriched in the evaporation system, causing the boiling point of the feed liquid to increase, seriously affecting the evaporation efficiency of the system, while also causing the system's processing capacity to decline and affecting the quality of the by-products. In addition, the existing evaporation treatment system lacks a pH adjustment device. When the pH value of the system is too high, it will cause scaling in the pipeline. When the pH value of the system is too low, it will affect the quality of the by-products.

[0004] Therefore, it is urgent to propose a new ferric phosphate wastewater evaporation treatment system to solve the problems of low evaporation efficiency, pipeline scaling and low by-product quality when the existing evaporation treatment system evaporates the ferric phosphate wastewater. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides an evaporation treatment system and an evaporation treatment method for iron phosphate wastewater that can be used to remove impurities and control the quality of ammonium sulfate by-products, aiming to solve the technical problems of low evaporation efficiency, pipeline scaling and low by-product quality caused by the existing evaporation treatment system when evaporating iron phosphate wastewater.

[0006] In the first aspect, an embodiment of the present application provides an evaporation treatment system for iron phosphate wastewater, comprising an evaporation unit, a centrifugal unit and an oxidation sedimentation unit connected in sequence, wherein the evaporation unit is used to evaporate the concentrated iron phosphate wastewater to obtain a first treatment liquid; the centrifugal unit is used to centrifugally treat the first treatment liquid to obtain a second treatment liquid and ammonium sulfate crystals; the oxidation sedimentation unit comprises an oxidizing unit and a sedimentation unit, the oxidizing unit is used to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid, and the sedimentation unit is used to neutralize and sediment the third treatment liquid to obtain ammonium sulfate sludge and a fourth treatment liquid; wherein a connecting pipe is arranged between the oxidizing unit and the sedimentation unit, and a pipeline mixer is arranged on the connecting pipe, and the pipeline mixer is filled with a pH adjuster.

[0007] In the technical solution of the embodiment of the present application, by setting an oxidizing subunit in the ferric phosphate wastewater evaporation treatment system, it can effectively utilize the characteristics of the incoming water, reduce energy consumption, and efficiently remove COD and / or chloride ions in the waste liquid of the evaporation treatment system without introducing new impurities, thereby significantly improving the evaporation efficiency and waste liquid treatment capacity of the evaporation treatment system, and at the same time improving the quality of the by-products; in addition, a pipeline mixer is also provided in the ferric phosphate wastewater evaporation treatment system, and the pH regulator in the pipeline mixer is used to directly adjust the pH value of the evaporation treatment system feed liquid, thereby controlling the pH value of the evaporation treatment system feed liquid, achieving the regulation of free acid and water content in the by-products, and removing some metal ions, thereby improving the quality of the by-products through the above-mentioned regulation and reducing the risk of pipeline scaling.

[0008] In some embodiments, the oxidation subunit includes an oxidation tank, and the sedimentation subunit includes a sedimentation tank, and the oxidation tank and the sedimentation tank are connected by a connecting pipe; wherein the oxidation tank is an enameled reactor with a jacket, and a feeding pipe is provided on the top of the enameled reactor, and the sedimentation tank is an enameled tank, and the bottom of the sedimentation tank is a conical structure.

[0009] In this embodiment, by arranging a jacket on the enameled reactor, the enameled reactor can be insulated, so that the oxidation reaction in the enameled reactor is maintained within a suitable temperature range, which can not only improve the reaction efficiency but also make the reaction more complete, thereby improving the removal efficiency of COD and / or chloride ions; by arranging a feeding pipe on the top of the enameled reactor, it is convenient to quickly and efficiently add materials to the enameled reactor; the bottom of the sedimentation tank is set to a conical structure, which can quickly settle solid particles and facilitate solid-liquid separation.

[0010] In some embodiments, the evaporation unit includes a preheater, a falling film evaporator, and a forced circulation evaporator which are sequentially connected through a pipeline; and the centrifugal unit includes a centrifuge.

[0011] In this embodiment, the preheater can preheat the concentrated iron phosphate wastewater, so as to improve the energy efficiency and treatment efficiency in the subsequent treatment process; the falling film evaporator has the advantages of high efficiency, energy saving, easy maintenance and reduced scaling when treating waste liquid; the forced circulation evaporator has the advantages of reduced scaling, easy cleaning and energy saving when treating waste liquid; by using the preheater, falling film evaporator and forced circulation evaporator in combination, the evaporation efficiency of the system can be significantly improved, and scaling can be reduced; the centrifuge facilitates solid-liquid separation.

[0012] In some embodiments, the iron phosphate wastewater evaporation treatment system also includes a drying unit, the drying unit includes a first drying subunit and a second drying subunit; the first drying subunit is connected to the centrifugal unit by a belt conveyor, and the belt conveyor is used to transport ammonium sulfate crystals to the first drying subunit for drying to obtain a first ammonium sulfate by-product; the second drying subunit is connected to the sedimentation subunit by an infusion pump, and the infusion pump is used to transport ammonium sulfate sludge to the second drying subunit for drying to obtain a second ammonium sulfate by-product.

[0013] In this embodiment, by providing a first drying subunit and a second drying subunit in the iron phosphate wastewater evaporation treatment system, the ammonium sulfate crystals and the ammonium sulfate sludge can be quickly dried respectively to obtain high-quality ammonium sulfate by-product.

[0014] In some embodiments, the pH adjuster is selected from at least one of an acid solution and an alkaline solution.

[0015] In this embodiment, cheap and readily available sulfuric acid can be used as the acid solution raw material, and ammonia water can be used as the alkaline solution raw material. By selecting the above-mentioned specific acid solution and alkaline solution, the introduction of new impurities can be avoided. At the same time, the pH value of the iron phosphate wastewater evaporation treatment system is adjusted by the above-mentioned pH adjuster to maintain it within a suitable range, thereby preventing pipe scaling and improving the quality of by-products.

[0016] In some embodiments, the sedimentation subunit is connected to the evaporation unit for returning the fourth treatment liquid to the evaporation unit.

[0017] In this embodiment, by connecting the sedimentation subunit with the evaporation unit, the waste liquid in the sedimentation subunit can be circulated and treated, thereby improving the utilization rate of the waste liquid in the iron phosphate wastewater evaporation treatment system.

[0018] In the second aspect, an embodiment of the present application provides a method for evaporating ferric phosphate wastewater using any of the above-mentioned evaporation treatment systems, comprising the following steps: passing the concentrated ferric phosphate wastewater into an evaporation unit for evaporation treatment to obtain a first treatment liquid; passing the first treatment liquid into a centrifugal unit for centrifugal treatment to obtain a second treatment liquid and ammonium sulfate crystals; passing the second treatment liquid into an oxidation subunit, and adding ammonium persulfate to carry out an oxidation reaction to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid; passing the third treatment liquid into a sedimentation subunit through a connecting pipe, and at the same time, a pH adjuster flows out from a pipeline mixer, enters the sedimentation subunit after passing through a connecting pipe for neutralization and sedimentation, and obtains ammonium sulfate sludge and a fourth treatment liquid.

[0019] In the technical solution of the embodiment of the present application, in the process of evaporating the acid iron wastewater using the above-mentioned evaporation treatment system, by adding ammonium persulfate to the oxidizing subunit, the ammonium persulfate is used to generate sulfate radicals with extremely strong oxidizing ability (its redox potential is 2.6V) under thermal activation, so as to achieve efficient oxidation of COD and chloride ions in the waste liquid, thereby achieving efficient removal of COD and chloride ions, thereby improving the quality of by-products; in addition, by adding a pH regulator to the sedimentation subunit, the pH value of the evaporation treatment system is adjusted, so as to achieve the regulation of free acid and water content in the by-products, thereby reducing pipeline scaling and improving the quality of by-products through the above-mentioned regulation.

[0020] In some embodiments, during the preparation of the first treatment solution, the pH value of the iron phosphate wastewater concentrate is 5-6.

[0021] In this embodiment, by controlling the pH value of the concentrated ferric phosphate wastewater solution within the scope of the present application, the subsequent rapid and efficient evaporation treatment of the concentrated solution is facilitated.

[0022] In some embodiments, during the preparation of the third treatment liquid, the pH value of the second treatment liquid is 2-3, the molar ratio of ammonium persulfate to COD in the second treatment liquid is (1-3):1; the temperature of the oxidation reaction is 80-90°C, and the time is 3-4h.

[0023] In this embodiment, by controlling the pH value of the second treatment liquid, the molar ratio of ammonium persulfate to COD in the second treatment liquid, and the temperature and time of the oxidation reaction within the scope of the present application, the oxidation reaction can be completed and the removal of COD can be improved. In addition, after the oxidation reaction is completed, ammonium persulfate can be converted into ammonium sulfate, further increasing the yield of by-products.

[0024] In some embodiments, during the preparation of ammonium sulfate sludge and the fourth treatment liquid, the neutralization sedimentation time is 0.2-1h, the pH value of the fourth treatment liquid is 5-6; and the step of refluxing the fourth treatment liquid to the evaporation unit is also included.

[0025] In this embodiment, by controlling the neutralization sedimentation time and the pH value of the fourth treatment liquid within the range of the present application, COD can be further removed, and some metal ions can be precipitated and removed at the bottom of the sedimentation tank to avoid enrichment in the system.

[0026] The beneficial effects of the present invention are as follows: different from the prior art, in the present application, an oxidizing subunit is arranged in the ferric phosphate wastewater evaporation treatment system, so that the characteristics of the incoming water can be effectively utilized without introducing new impurities, energy consumption can be reduced, and COD and / or chloride ions in the waste liquid of the evaporation treatment system can be efficiently removed, thereby significantly improving the evaporation efficiency and the ability of the evaporation treatment system to treat waste liquid, and at the same time improving the quality of the by-products; in addition, a pipeline mixer is also provided in the ferric phosphate wastewater evaporation treatment system, and the pH regulator in the pipeline mixer is used to directly adjust the pH of the entire evaporation treatment system, thereby controlling the pH value of the evaporation treatment system feed liquid, achieving the regulation of free acid and water content in the by-products, and removing some metal ions, thereby improving the quality of the by-products through the above-mentioned regulation and reducing the risk of pipeline scaling.

[0027] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a structural schematic diagram of the iron phosphate wastewater evaporation treatment system in the present invention; The reference numerals have the following meanings: 1: evaporation unit; 2: centrifugation unit; 3: oxidation subunit; 4: sedimentation subunit; 5: pipeline mixer; 6: first drying subunit; 7: second drying subunit. DETAILED DESCRIPTION

[0030] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0032] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0035] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0036] At present, the industry often uses an evaporation treatment system to deeply treat iron phosphate wastewater. However, as the evaporation proceeds, the COD and impurity ions in the iron phosphate wastewater will continue to accumulate in the evaporation system, causing the boiling point of the feed liquid to increase, seriously affecting the evaporation efficiency of the system, while also causing the system's processing capacity to decline and affecting the quality of the by-products. In addition, the existing evaporation treatment system lacks a pH adjustment device. When the pH value of the system is too high, it will cause scaling in the pipeline. When the pH value of the system is too low, it will seriously affect the quality of the by-products.

[0037] In order to solve the technical problems that the existing evaporation treatment system will cause low evaporation efficiency, pipeline scaling and low by-product quality when evaporating iron phosphate wastewater, the present application provides an evaporation treatment system and an evaporation treatment method for iron phosphate wastewater.

[0038] like Figure 1As shown, in the first aspect, an embodiment of the present application provides an evaporation treatment system for iron phosphate wastewater, comprising an evaporation unit 1, a centrifugal unit 2 and an oxidation sedimentation unit 3 connected in sequence, wherein the evaporation unit 1 is used to evaporate the concentrated iron phosphate wastewater to obtain a first treatment liquid; the centrifugal unit 2 is used to centrifuge the first treatment liquid to obtain a second treatment liquid and ammonium sulfate crystals; the oxidation sedimentation unit comprises an oxidizing unit 3 and a sedimentation unit 4, the oxidizing unit 3 is used to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid, and the sedimentation unit 4 is used to neutralize and sediment the third treatment liquid to obtain ammonium sulfate sludge and a fourth treatment liquid; wherein a connecting pipe is arranged between the oxidizing unit 3 and the sedimentation unit 4, and a pipe mixer 5 is arranged on the connecting pipe, and the pipe mixer 5 is filled with a pH adjuster.

[0039] In the technical solution of the embodiment of the present application, by setting an oxidation subunit 3 in the ferric phosphate wastewater evaporation treatment system, without introducing new impurities, it can effectively utilize the characteristics of the incoming water, reduce energy consumption, and efficiently remove COD and / or chloride ions in the waste liquid of the evaporation treatment system, significantly improve the evaporation efficiency and waste liquid treatment capacity of the evaporation treatment system, and at the same time improve the quality of the by-products; in addition, the ferric phosphate wastewater evaporation treatment system is also provided with a pipeline mixer 5, and the pH regulator in the pipeline mixer 5 is used to directly adjust the pH of the entire evaporation treatment system, which solves the problem that the existing evaporation system lacks a pH adjustment device and mainly relies on adjusting the pH of the feed pH control system, which makes it difficult to accurately control the pH value of the evaporation treatment process section; in addition, by setting the pipeline mixer 5, it adjusts the pH value of the evaporation treatment system feed liquid, on the one hand, realizes the adjustment of the free acid and water content in the by-product, and then improves the quality of the by-product through the above-mentioned regulation, and on the other hand, it can also improve the sedimentation effect in the sedimentation subunit 4, and effectively remove a part of the metal ions to avoid scaling of the evaporation treatment system.

[0040] Furthermore, in some embodiments, the oxidizing subunit 3 includes an oxidation tank, and the settling subunit 4 includes a settling tank, and the oxidation tank and the settling tank are connected by a connecting pipe; wherein the oxidation tank is an enameled reactor with a jacket, and a feeding pipe is provided on the top of the enameled reactor, and the settling tank is an enameled tank, and the bottom of the settling tank is a conical structure.

[0041] In the technical solution of the embodiment of the present application, by arranging a jacket on the enameled reactor, the enameled reactor can be insulated, so that the oxidation reaction in the enameled reactor is maintained within a suitable temperature range, which can not only improve the reaction efficiency but also make the reaction more complete, thereby improving the removal efficiency of COD and / or chloride ions; by arranging a feeding pipe on the top of the enameled reactor, it is convenient to quickly and efficiently add materials to the enameled reactor; the bottom of the sedimentation tank is set to a conical structure, which can quickly settle solid particles and facilitate solid-liquid separation.

[0042] Further, in some embodiments, the evaporation unit 1 includes a preheater, a falling film evaporator, and a forced circulation evaporator which are sequentially connected through pipelines; and the centrifugal unit 2 includes a centrifuge.

[0043] In the technical solution of the embodiment of the present application, the preheater can preheat the concentrated iron phosphate wastewater, so as to improve the energy efficiency and treatment efficiency in the subsequent treatment process; the falling film evaporator has the advantages of high efficiency, energy saving, easy maintenance and reduced scaling when treating waste liquid; the forced circulation evaporator has the advantages of reduced scaling, easy cleaning and energy saving when treating waste liquid; by using the preheater, falling film evaporator and forced circulation evaporator in combination, the evaporation efficiency of the system can be significantly improved, and scaling can be reduced; the centrifuge facilitates solid-liquid separation.

[0044] Furthermore, in some embodiments, the iron phosphate wastewater evaporation treatment system also includes a drying unit, the drying unit includes a first drying subunit 6 and a second drying subunit 7; the first drying subunit 6 is connected to the centrifugal unit 2 by a belt conveyor, and the belt conveyor is used to transport ammonium sulfate crystals to the first drying subunit 6 for drying to obtain a first ammonium sulfate by-product; the second drying subunit 7 is connected to the sedimentation subunit 4 by an infusion pump, and the infusion pump is used to transport ammonium sulfate sludge to the second drying subunit 7 for drying to obtain a second ammonium sulfate by-product.

[0045] In the technical solution of the embodiment of the present application, by setting the first drying subunit 6 and the second drying subunit 7 in the iron phosphate wastewater evaporation treatment system, the ammonium sulfate crystals and the ammonium sulfate sludge can be quickly dried respectively to obtain high-quality ammonium sulfate by-product.

[0046] Furthermore, in some embodiments, the pH adjuster is selected from at least one of an acid solution and an alkaline solution.

[0047] In the technical solution of the embodiment of the present application, cheap and readily available sulfuric acid can be used as the raw material for the acid solution, and ammonia water can be used as the raw material for the alkaline solution. By selecting the above-mentioned specific acid solution and alkaline solution, the introduction of new impurities can be avoided. At the same time, the pH value of the iron phosphate wastewater evaporation treatment system is adjusted by the above-mentioned pH adjuster to maintain it within an appropriate range, thereby preventing pipe scaling and improving the quality of by-products.

[0048] It can be understood that the acid solution and the alkaline solution can be conventionally selected according to the actual use needs. In the present application, the pH adjuster is preferably an alkaline solution, and the alkaline solution is preferably ammonia water. On the one hand, the added ammonia water can adjust the pH of the system to an appropriate range. On the other hand, ammonia water can be converted into ammonium sulfate by-product, which significantly improves the utilization rate of the raw materials.

[0049] Further, in some embodiments, the sedimentation subunit 4 is connected to the evaporation unit 1 for returning the fourth treatment liquid to the evaporation unit 1 .

[0050] In the technical solution of the embodiment of the present application, by connecting the sedimentation subunit 4 with the evaporation unit 1, the waste liquid in the sedimentation subunit 4 can be circulated and treated, thereby improving the utilization rate of the waste liquid in the iron phosphate wastewater evaporation treatment system.

[0051] In the second aspect, an embodiment of the present application provides a method for evaporating ferric phosphate wastewater using any of the above-mentioned evaporation treatment systems, comprising the following steps: passing the concentrated ferric phosphate wastewater into an evaporation unit 1 for evaporation treatment to obtain a first treatment liquid; passing the first treatment liquid into a centrifugal unit 2 for centrifugal treatment to obtain a second treatment liquid and ammonium sulfate crystals; passing the second treatment liquid into an oxidizing subunit 3, and adding ammonium persulfate to carry out an oxidation reaction to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid; passing the third treatment liquid into a sedimentation subunit 4 through a connecting pipe, and at the same time, a pH adjuster flows out from a pipeline mixer 5, and enters the sedimentation subunit 4 through a connecting pipe for neutralization and sedimentation to obtain ammonium sulfate sludge and a fourth treatment liquid.

[0052] In the technical solution of the embodiment of the present application, in the process of evaporating the acid iron wastewater using the above-mentioned evaporation treatment system, by adding ammonium persulfate to the oxidizing subunit 3, ammonium persulfate is used to generate sulfate radicals with extremely strong oxidizing ability (its redox potential is 2.6V) under thermal activation, so as to achieve efficient oxidation of COD and chloride ions in the waste liquid, thereby achieving efficient removal of COD and chloride ions, thereby improving the quality of by-products; in addition, by adding a pH regulator to the sedimentation subunit 4, the pH value of the evaporation treatment system is adjusted. On the one hand, the free acid and water content in the by-product are regulated, and the quality of the by-product is improved through the above-mentioned regulation. On the other hand, the sedimentation effect in the sedimentation subunit 4 can be improved, and a part of the metal ions can be effectively removed to avoid scaling of the evaporation treatment system.

[0053] Furthermore, in some embodiments, during the preparation of the first treatment solution, the pH value of the concentrated ferric phosphate wastewater solution is 5-6.

[0054] In the technical solution of the embodiment of the present application, by controlling the pH value of the concentrated ferric phosphate wastewater to 5-6, the subsequent rapid and efficient evaporation treatment of the concentrated solution is facilitated; if the pH value of the concentrated ferric phosphate wastewater is too low, the free acid and water content in the ammonium sulfate by-product will be too high, and the product quality will be reduced; if the pH value of the concentrated ferric phosphate wastewater is too high, the evaporation equipment will cause scaling of the tubes due to element enrichment.

[0055] Specifically, the pH value of the iron phosphate wastewater concentrate can be, for example, 5, 5.2, 5.4, 5.6, 5.8, 6 or other values ​​within this range.

[0056] Furthermore, in some embodiments, during the preparation of the third treatment liquid, the pH value of the second treatment liquid is 2-3, the molar ratio of ammonium persulfate to COD in the second treatment liquid is (1-3):1; the temperature of the oxidation reaction is 80-90°C, and the time is 3-4h.

[0057] In the technical scheme of the embodiment of the present application, by controlling the pH value of the second treatment liquid to 2~3, the molar ratio of ammonium persulfate to COD in the second treatment liquid to (1~3): 1, the temperature of the oxidation reaction is 80~90°C, and the time is 3~4h, the oxidation reaction can be completed and the removal of COD can be improved. In addition, after the oxidation reaction is completed, ammonium persulfate can be converted into ammonium sulfate, further increasing the yield of by-products without introducing new impurities; if the pH value of the second treatment liquid is too low or too high, it will affect the thermal activation effect, resulting in a low COD removal rate. If the molar ratio of ammonium sulfate to COD in the second treatment liquid is too low, and the temperature and time of the oxidation reaction are too short, the oxidation reaction is incomplete, reducing the COD removal rate; if the molar ratio of ammonium sulfate to COD in the second treatment liquid is too high, and the temperature and time of the oxidation reaction are too long, raw materials will be wasted and energy consumption will increase.

[0058] Specifically, the pH value of the second treatment liquid can be, for example, 2, 2.2, 2.4, 2.6, 2.8, 3 or other values ​​within the range; the molar ratio of ammonium persulfate to COD in the second treatment liquid can be, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1 or other values ​​within the range; the temperature of the oxidation reaction can be, for example, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C or other values ​​within the range; the time can be, for example, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h or other values ​​within the range.

[0059] Furthermore, in some embodiments, during the preparation of ammonium sulfate sludge and the fourth treatment liquid, the neutralization sedimentation time is 0.2 to 1 h, and the pH value of the fourth treatment liquid is 5 to 6; and the step of refluxing the fourth treatment liquid to the evaporation unit 1 is also included.

[0060] Specifically, the neutralization sedimentation time can be, for example, 0.2h, 0.4h, 0.6h, 0.8h, 1h or other values ​​within this range; the pH value of the fourth treatment liquid can be, for example, 5, 5.2, 5.4, 5.6, 5.8, 6 or other values ​​within this range.

[0061] In the technical solution of the embodiment of the present application, by controlling the neutralization and sedimentation time to 0.2~1h, the pH value of the fourth treatment liquid is 5~6, which can further remove COD, and precipitate and remove some metal ions at the bottom of the sedimentation tank to avoid enrichment in the system; if the neutralization and sedimentation time is too short, the sedimentation is not thorough, which will reduce the removal rate of COD and some metal ions; if the neutralization and sedimentation time is too long, a larger volume of sedimentation tank is required for storing the feed liquid, resulting in increased costs; in addition, the fourth treatment liquid is returned to the evaporation unit 1, which can adjust the pH value of the iron phosphate wastewater concentrate, which is convenient for the subsequent efficient treatment of the iron phosphate wastewater concentrate.

[0062] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0063] 1. Ferric phosphate wastewater evaporation treatment system and method Example 1 A ferric phosphate wastewater evaporation treatment system comprises an evaporation unit 1, a centrifugal unit 2 and an oxidation sedimentation unit which are connected in sequence; The evaporation unit 1 is used to evaporate the concentrated ferric phosphate wastewater to obtain a first treated liquid; The centrifugal unit 2 is used to centrifuge the first treatment liquid to obtain a second treatment liquid and ammonium sulfate crystals; The oxidation sedimentation unit includes an oxidation subunit 3 and a sedimentation subunit 4, wherein the oxidation subunit 3 is used to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid, and the sedimentation subunit 4 is used to neutralize and sediment the third treatment liquid to obtain ammonium sulfate sludge and a fourth treatment liquid; A connecting pipe is provided between the oxidizing subunit 3 and the settling subunit 4, and a pipe mixer 5 is provided on the connecting pipe, and the pipe mixer 5 is filled with a pH adjusting agent; Among them, the oxidizing subunit 3 includes an oxidizing tank, and the settling subunit 4 includes a settling tank. The oxidizing tank and the settling tank are connected by a connecting pipe; the oxidizing tank is an enamel reactor with a jacket, and a feeding pipe is arranged on the top of the enamel reactor, and the settling tank is an enamel tank, and the bottom of the settling tank is a conical structure; The evaporation unit 1 includes a preheater, a falling film evaporator and a forced circulation evaporator which are sequentially connected through pipelines; the centrifugal unit 2 includes a centrifuge; The invention also includes a drying unit, which includes a first drying subunit 6 and a second drying subunit 7; the first drying subunit 6 is connected to the centrifugal unit 2 by a belt conveyor, and the belt conveyor is used to transport the ammonium sulfate crystals to the first drying subunit 6 for drying to obtain a first ammonium sulfate by-product; the second drying subunit 7 is connected to the sedimentation subunit 4 by an infusion pump, and the infusion pump is used to transport the ammonium sulfate sludge to the second drying subunit 7 for drying to obtain a second ammonium sulfate by-product.

[0064] The method for evaporating iron acid wastewater using the evaporation treatment system comprises the following steps: S1, passing the concentrated ferric phosphate wastewater into an evaporation unit 1 for evaporation treatment to obtain a first treated liquid; S2, passing the first treatment liquid into the centrifugal unit 2 for centrifugal treatment to obtain a second treatment liquid and ammonium sulfate crystals; S3, passing the second treatment liquid (pH value is 2.09, COD is 1130 mg / L, chlorine content is 1985.56 ppm, aluminum content is 9.90 ppm, calcium content is 557.70 ppm, magnesium content is 470.17 ppm, manganese content is 678.90 ppm, iron content is 52.27 ppm) into the oxidizing subunit 3, and 11.18 g / L of ammonium persulfate is added at a temperature of 85° C. and reacted for 3.5 hours to remove COD and / or chloride ions in the second treatment liquid, thereby obtaining a third treatment liquid; S4, the third treatment liquid is passed into the sedimentation subunit 4 through the connecting pipe, and the ammonia water flows out from the pipeline mixer 5, and enters the sedimentation subunit 4 through the connecting pipe for neutralization and sedimentation. The ammonia water in the sedimentation subunit 4 is 67g / L, and the sedimentation time is 0.5h, to obtain ammonium sulfate sludge and the fourth treatment liquid, and the fourth treatment liquid is refluxed to the evaporation unit 1.

[0065] Example 2 The method for evaporating the acid iron wastewater in this embodiment is basically the same as that in Embodiment 1, except that in step S3, 14.90 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 69 g / L.

[0066] Example 3 The method for evaporating the acid iron wastewater in this embodiment is basically the same as that in Embodiment 1, except that in step S3, 18.63 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 70 g / L.

[0067] Example 4 The method for evaporating acid iron wastewater in this embodiment is basically the same as that in Example 1, except that in step S3, the pH value of the second treatment liquid is 2.15, the COD is 2315 mg / L, the chlorine content is 3257.20 ppm, the aluminum content is 10.13 ppm, the calcium content is 445.67 ppm, the magnesium content is 483.20 ppm, the manganese content is 1102.63 ppm, the iron content is 34.53 ppm, and 19.84 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 123 g / L.

[0068] Example 5 The method for evaporating acid iron wastewater in this embodiment is basically the same as that in Example 1, except that in step S3, the pH value of the second treatment liquid is 2.15, the COD is 2315 mg / L, the chlorine content is 3257.20 ppm, the aluminum content is 10.13 ppm, the calcium content is 445.67 ppm, the magnesium content is 483.20 ppm, the manganese content is 1102.63 ppm, the iron content is 34.53 ppm, and 26.46 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 137 g / L.

[0069] Example 6 The method for evaporating acid iron wastewater in this embodiment is basically the same as that in Example 1, except that in step S3, the pH value of the second treatment liquid is 2.15, the COD is 2315 mg / L, the chlorine content is 3257.20 ppm, the aluminum content is 10.13 ppm, the calcium content is 445.67 ppm, the magnesium content is 483.20 ppm, the manganese content is 1102.63 ppm, the iron content is 34.53 ppm, and 33.07 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 147 g / L.

[0070] Example 7 The method for evaporating the acid iron wastewater in this embodiment is basically the same as that in Example 1, except that, in step S3, the pH value of the second treatment liquid is 2.08, the COD is 6140 mg / L, the chlorine content is 4230.51 ppm, the aluminum content is 9.6 ppm, the calcium content is 442.10 ppm, the magnesium content is 222.05 ppm, the manganese content is 548.75 ppm, the iron content is 53.35 ppm, and 84.17 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 146.39 g / L.

[0071] Example 8 The method for evaporating the acid iron wastewater in this embodiment is basically the same as that in Example 1, except that, in step S3, the pH value of the second treatment liquid is 2.08, the COD is 6140 mg / L, the chlorine content is 4230.51 ppm, the aluminum content is 9.6 ppm, the calcium content is 442.10 ppm, the magnesium content is 222.05 ppm, the manganese content is 548.75 ppm, the iron content is 53.35 ppm, and 105.89 g / L of ammonium persulfate is added; in step S4, the ammonia water in the sedimentation subunit 4 is 191.26 g / L.

[0072] Comparative Example 1 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 1, except that, in step S4, no ammonia water is added.

[0073] Comparative Example 2 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 2, except that, in step S4, no ammonia water is added.

[0074] Comparative Example 3 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 3, except that in step S4, no ammonia water is added.

[0075] Comparative Example 4 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 4, except that in step S4, no ammonia water is added.

[0076] Comparative Example 5 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 5, except that in step S4, no ammonia water is added.

[0077] Comparative Example 6 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 6, except that in step S4, no ammonia water is added.

[0078] Comparative Example 7 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 7, except that, in step S4, no ammonia water is added.

[0079] Comparative Example 8 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 8, except that, in step S4, no ammonia water is added.

[0080] Comparative Example 9 The method for evaporating the acid iron wastewater in this comparative example is basically the same as that in Example 1, except that step S3 is not performed.

[0081] 2. Test Method The pH value, COD, chlorine content, aluminum content, calcium content, magnesium content, manganese content and iron content of the fourth treatment liquid obtained by treatment in Examples 1-8 and Comparative Examples 1-8 were tested, wherein the COD was tested by HJ / T399 2007 rapid digestion spectrophotometry, the chlorine content was tested by chloride ion selective electrode method, the aluminum content, calcium content, magnesium content, manganese content and iron content were tested by inductively coupled plasma optical emission spectrometry (ICP-OES), and the removal rates of COD, chlorine, aluminum, calcium, magnesium, manganese and iron were calculated, and the results are shown in Table 1 below.

[0082] III. Analysis of test results of various embodiments and comparative examples Table 1 pH value of the fourth treatment liquid and removal rates of COD, chlorine, aluminum, calcium, magnesium, manganese and iron

[0083] In the table, “-” means that after the second treatment liquid was treated, the content of some metal ions increased and the removal rate could not be calculated.

[0084] As can be seen from Table 1, compared with the comparative example 9 in which no ammonium persulfate was added for oxidation treatment, the removal rates of COD and chlorine in the fourth treated liquid obtained after the addition of ammonium persulfate for oxidation treatment in Example 1 were significantly increased. The results show that the use of ammonium persulfate to treat the iron phosphate wastewater concentrate in the present application can efficiently remove COD and chlorine; compared with the comparative examples 1-8 in which no ammonia water was added, the removal rates of COD and chlorine in the fourth treated liquid obtained after the addition of ammonia water in Examples 1-8 were significantly increased, and the removal rates of aluminum, calcium, magnesium, manganese, iron, etc. were also increased. The results show that after the addition of ammonia water in the present application, COD, chlorine and some metal ions can be further removed.

[0085] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A ferric phosphate wastewater evaporation treatment system, characterized in that: It includes an evaporation unit, a centrifugal unit and an oxidation sedimentation unit which are connected in sequence, wherein: The evaporation unit is used to evaporate the concentrated ferric phosphate wastewater to obtain a first treated liquid; The centrifugal unit is used to centrifuge the first treatment liquid to obtain a second treatment liquid and ammonium sulfate crystals; The oxidation and sedimentation unit comprises an oxidation subunit and a sedimentation subunit, wherein the oxidation subunit is used to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid, and the sedimentation subunit is used to neutralize and sediment the third treatment liquid to obtain ammonium sulfate sludge and a fourth treatment liquid; Wherein, a connecting pipe is arranged between the oxidizing subunit and the settling subunit, and a pipeline mixer is arranged on the connecting pipe, and the pipeline mixer is filled with a pH adjusting agent.

2. The iron phosphate wastewater evaporation treatment system according to claim 1, characterized in that: The oxidizing subunit includes an oxidizing tank, the settling subunit includes a settling tank, and the oxidizing tank and the settling tank are connected via the connecting pipe; The oxidation tank is an enameled reactor with a jacket, and a feeding pipe is arranged on the top of the enameled reactor; the sedimentation tank is an enameled tank, and the bottom of the sedimentation tank is a conical structure.

3. The iron phosphate wastewater evaporation treatment system according to claim 1, characterized in that: The evaporation unit comprises a preheater, a falling film evaporator and a forced circulation evaporator which are sequentially connected through pipelines; The centrifugal unit includes a centrifuge.

4. The iron phosphate wastewater evaporation treatment system according to claim 1, characterized in that: Also included is a drying unit, the drying unit comprising a first drying sub-unit and a second drying sub-unit; The first drying subunit is connected to the centrifugal unit via a belt conveyor, and the belt conveyor is used to transport the ammonium sulfate crystals to the first drying subunit for drying to obtain a first ammonium sulfate by-product; The second drying subunit is connected to the sedimentation subunit via an infusion pump, and the infusion pump is used to transport the ammonium sulfate sludge to the second drying subunit for drying to obtain a second ammonium sulfate by-product.

5. The iron phosphate wastewater evaporation treatment system according to claim 1, characterized in that: The pH adjuster is selected from at least one of an acid solution and an alkaline solution.

6. The iron phosphate wastewater evaporation treatment system according to claim 1, characterized in that: The sedimentation subunit is connected to the evaporation unit and is used for returning the fourth treatment liquid to the evaporation unit.

7. A method for evaporating iron phosphate wastewater using the evaporation treatment system according to any one of claims 1 to 6, characterized in that: The steps include: Passing the concentrated ferric phosphate wastewater into an evaporation unit for evaporation treatment to obtain a first treated liquid; Passing the first treatment liquid into a centrifugal unit for centrifugal treatment to obtain a second treatment liquid and ammonium sulfate crystals; Passing the second treatment liquid into an oxidation subunit, and adding ammonium persulfate to perform an oxidation reaction to remove COD and / or chloride ions in the second treatment liquid to obtain a third treatment liquid; The third treatment liquid is introduced into the sedimentation subunit through the connecting pipe, and the pH adjuster flows out from the pipeline mixer, enters the sedimentation subunit through the connecting pipe for neutralization and sedimentation, and obtains ammonium sulfate sludge and the fourth treatment liquid.

8. The method according to claim 7, characterized in that During the preparation of the first treatment solution, the pH value of the iron phosphate wastewater concentrate is 5-6.

9. The method according to claim 7, characterized in that: In the preparation process of the third treatment liquid, the pH value of the second treatment liquid is 2-3, and the molar ratio of the ammonium persulfate to the COD in the second treatment liquid is (1-3):1; The temperature of the oxidation reaction is 80-90° C. and the time is 3-4 hours.

10. The method according to claim 7, characterized in that In the preparation process of the ammonium sulfate sludge and the fourth treatment liquid, the neutralization sedimentation time is 0.2-1h, and the pH value of the fourth treatment liquid is 5-6; and the method also includes the step of refluxing the fourth treatment liquid into the evaporation unit.

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