A method for treating sulfate high-salinity wastewater

Abstract

The application relates to a sulfate high-salt wastewater treatment method, which comprises the following steps: providing sulfate high-salt wastewater in an alumina preparation process; carrying out deamination treatment on the sulfate high-salt wastewater to obtain deamination tail liquid; sending the deamination tail liquid to a bauxite grinding process, so that the deamination tail liquid finally enters a slurry formed by bauxite grinding. The deamination tail liquid obtained by carrying out deamination treatment on the sulfate high-salt wastewater is sent to the bauxite grinding process, so that the deamination tail liquid finally enters the slurry formed by bauxite grinding. The sulfate ions in the final slurry are finally mixed into red mud, and the remaining substances in the sulfate high-salt wastewater can be recycled or treated in the alumina preparation process.

Description

Technical Field

[0001] This application relates to the field of environmental protection, and in particular to industrial wastewater treatment. Background Technology

[0002] High-salinity sulfate wastewater refers to wastewater primarily containing sulfates. The usual treatment method involves recovering some of the sulfates and then further treating the remaining wastewater. However, the market demand for the recovered sulfates is small, and the remaining wastewater has a complex composition, often containing large amounts of harmful elements, resulting in high treatment costs. For example, high-salinity sulfate wastewater from alumina production processes is a typical example. Besides sodium sulfate and ammonium sulfate, it also contains impurities such as arsenic, fluorine, chlorine, and oxalate. Purifying and treating the vanadium precipitation tailings from the alumina process is costly and complex, and the resulting sodium sulfate has low market demand and economic value. Summary of the Invention

[0003] This application provides a method for treating high-salt sulfate wastewater to solve the technical problem of difficult disposal of high-salt sulfate wastewater.

[0004] This application provides a method for treating high-salinity sulfate wastewater, which includes the following steps:

[0005] Provides high-salt sulfate wastewater;

[0006] The high-salt sulfate wastewater was subjected to ammonia removal treatment to obtain ammonia removal tailings.

[0007] The deammoniation tailings are sent to the bauxite grinding process, so that the deammoniation tailings eventually enter the slurry formed by bauxite grinding.

[0008] In some embodiments of this application, the high-salt sulfate wastewater is the vanadium extraction tail liquid from the Bayer process for producing alumina.

[0009] In some embodiments of this application, the method for treating high-salt sulfate wastewater further includes the following steps:

[0010] Determine whether the total silicon-sulfur ratio of the deammoniation tailings and bauxite in the grinding process reaches 6 or above. If the silicon-sulfur ratio does not reach 6 or above, add raw materials containing silicon dioxide to the bauxite until the silicon-sulfur ratio reaches 6 or above.

[0011] The deammoniation tailings are ultimately fed into the slurry formed by bauxite grinding;

[0012] The slurry is subjected to leaching treatment.

[0013] In some embodiments of this application, the method for treating high-salt sulfate wastewater further includes the following steps:

[0014] Determine whether the total silicon-sulfur ratio of the deammoniation tailings and bauxite in the grinding process reaches 4 or above. If the silicon-sulfur ratio does not reach 4 or above, add raw materials containing silicon dioxide to the bauxite until the silicon-sulfur ratio reaches 4 or above.

[0015] The deammoniation tailings are ultimately fed into the slurry formed by bauxite grinding;

[0016] The slurry is subjected to pre-desiliconization treatment;

[0017] The slurry after pre-desiliconization treatment is subjected to leaching treatment.

[0018] In some embodiments of this application, the solid content of the slurry is 180-220 g / L, and the amount of the deammoniation tailings entering the slurry formed by bauxite grinding is 2-15 L per cubic meter of slurry.

[0019] In some embodiments of this application, the silica-containing raw material includes at least one of low-grade bauxite, low-grade bauxite, kaolin, glass, chlorite, diatomite, and silica molecular sieve.

[0020] In some embodiments of this application, the dissolution temperature is above 200°C; and / or,

[0021] The dissolution treatment time is 5 minutes or more.

[0022] In some embodiments of this application, the method for treating high-salt sulfate wastewater further includes the following steps:

[0023] Ammonium sulfate is obtained by absorbing the ammonia gas obtained from the deamination with dilute sulfuric acid.

[0024] The ammonium sulfate is returned as a vanadium precipitant to the vanadium extraction step in the alumina preparation process.

[0025] In some embodiments of this application, the deamination is carried out as follows:

[0026] Add calcium oxide or sodium hydroxide to the high-salt sulfate wastewater to allow ammonia gas to escape.

[0027] In some embodiments of this application, the deammoniation is carried out at a temperature above 50°C.

[0028] The technical solutions provided in this application have the following advantages compared with the prior art:

[0029] The method for treating high-salt sulfate wastewater provided in this application involves sending the deammoniation tailings obtained after deammoniation treatment of the high-salt sulfate wastewater to the bauxite grinding process, so that the deammoniation tailings eventually enter the slurry formed by bauxite grinding. Finally, the sulfate ions in the slurry will be mixed into the red mud, while the remaining substances in the high-salt sulfate wastewater can be recovered or treated in the alumina preparation process. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic flowchart of a method for treating high-salt sulfate wastewater provided in an embodiment of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise specified, the terminology used herein should be understood as having the meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any conflict, this specification shall prevail.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0036] Currently, there are technical difficulties in treating high-salt sulfate wastewater.

[0037] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0038] This application provides a method for treating high-salinity sulfate wastewater, which includes the following steps:

[0039] S1: Provides high-salt sulfate wastewater;

[0040] S2: The high-salt sulfate wastewater is subjected to ammonia removal treatment to obtain ammonia removal tail liquid;

[0041] S3: The deammoniation tailings are sent to the bauxite grinding process, so that the deammoniation tailings are finally incorporated into the slurry formed by bauxite grinding.

[0042] It is easy to understand that the alumina leaching process is carried out under strong alkalinity and high temperature. If the high-salt sulfate wastewater contains a large amount of ammonia, then when it participates in the alumina leaching process, the ammonia will volatilize in large quantities under strong alkalinity and high temperature, causing toxicity to the production environment. Therefore, by treating the high-salt sulfate wastewater to remove ammonia, the high-salt sulfate wastewater can then participate in the alumina leaching process.

[0043] It's easy to understand that after bauxite is ground to form a slurry, the slurry undergoes a leaching process. A large amount of aluminum compounds in the bauxite will dissolve in the form of sodium aluminate, while the undissolved substance becomes red mud. Sodium aluminosilicate is generated during the leaching process, and this sodium aluminosilicate enters the red mud, with sulfate ions also becoming trapped within it.

[0044] This application involves sending the deammoniation tailings obtained from the deammoniation treatment of high-salt sulfate wastewater to the bauxite grinding process, so that the deammoniation tailings eventually enter the slurry formed by bauxite grinding. Finally, the sulfate ions in the slurry will be mixed into the red mud, while the remaining substances in the high-salt sulfate wastewater can be recovered or treated in the alumina preparation process.

[0045] In some embodiments of this application, the high-salt sulfate wastewater is the vanadium extraction tail liquid from the Bayer process for producing alumina.

[0046] For vanadium extraction tailings, the remaining vanadium, arsenic, fluorine, sodium oxalate, and other substances in the tailings will be recycled with the alumina production system and returned to the alumina vanadium removal process, ultimately forming vanadium slag in the alumina process, thus recovering and utilizing vanadium. Sodium sulfate is ultimately mixed into the red mud, while the remaining substances in the high-salt sulfate wastewater can be recovered or treated in the alumina preparation process.

[0047] In some embodiments of this application, the method for treating high-salt sulfate wastewater further includes the following steps:

[0048] S311: Determine whether the total silicon-sulfur ratio of the deammoniation tailings and bauxite in the grinding process reaches 6 or above. If the silicon-sulfur ratio does not reach 6 or above, add raw materials containing silicon dioxide to the bauxite until the silicon-sulfur ratio reaches 6 or above.

[0049] S312: The deammoniation tailings is ultimately fed into the slurry formed by bauxite grinding;

[0050] S313: The slurry is subjected to leaching treatment.

[0051] In some embodiments of this application, the method for treating high-salt sulfate wastewater further includes the following steps:

[0052] S321: Determine whether the total silicon-sulfur ratio of the deammoniation tailings and bauxite in the grinding process reaches 4 or above. If the silicon-sulfur ratio does not reach 4 or above, add raw materials containing silicon dioxide to the bauxite until the silicon-sulfur ratio reaches 4 or above.

[0053] S322: The deammoniation tailings is ultimately fed into the slurry formed by bauxite grinding;

[0054] S323: Perform pre-desiliconization treatment on the slurry;

[0055] S324: Perform leaching treatment on the slurry after pre-desiliconization treatment.

[0056] It should be noted that in this application, the silicon-sulfur ratio is defined as the molar ratio of sulfate ions in active silica.

[0057] It should be noted that some alumina manufacturers' production processes do not include a pre-desiliconization step, while others do. Steps S311 to S313 do not include a pre-desiliconization treatment of the slurry. Steps S321 to S324 include a pre-desiliconization treatment of the slurry. Pre-desiliconization of the slurry will result in more sulfate ions being incorporated into the sodium aluminosilicate. Therefore, when a pre-desiliconization step is present, a silica-sulfur ratio of 4 or higher is sufficient to effectively enrich sulfate ions in the red mud. When a pre-desiliconization step is absent, a silica-sulfur ratio of 6 or higher is preferable.

[0058] It should be noted that the aforementioned limitation on the silicon-sulfur ratio is intended to ensure that more sulfate ions are incorporated into the sodium aluminosilicate, allowing all sulfate ions introduced from the deammoniation tail liquor to be incorporated into the sodium aluminosilicate. However, the circulating mother liquor in the alumina production process itself contains sodium sulfate. Even if not all sulfate ions introduced from the deammoniation tail liquor are incorporated into the sodium aluminosilicate, some will ultimately remain in the sodium aluminate solution obtained from the leaching treatment, which will not significantly affect the overall alumina production process. Therefore, the aforementioned limitation on the silicon-sulfur ratio is not a necessary condition for the implementation of this invention.

[0059] In some embodiments of this application, the silica-containing raw material includes at least one of low-grade bauxite, kaolin, glass, chlorite, diatomite, and silica molecular sieve.

[0060] In some embodiments of this application, the leaching temperature is above 200°C.

[0061] It is easy to understand that a dissolution temperature above 200℃ allows aluminum-containing compounds to dissolve completely.

[0062] In some embodiments of this application, the dissolution treatment time is 5 minutes or more.

[0063] It is easy to understand that a dissolution treatment time of 5 minutes or more can ensure that aluminum-containing compounds are fully dissolved.

[0064] In some embodiments of this application, the method for treating high-salt sulfate wastewater further includes the following steps:

[0065] S4: Ammonium sulfate is obtained by absorbing the ammonia gas obtained from the deamination with dilute sulfuric acid;

[0066] S5: Return the ammonium sulfate to the vanadium extraction step in the alumina preparation process.

[0067] It's easy to understand that bauxite usually contains a certain amount of vanadium, so the alumina preparation process generally includes a vanadium extraction step.

[0068] In some embodiments of this application, the deamination is carried out as follows:

[0069] Add calcium oxide or sodium hydroxide to the high-salt sulfate wastewater to allow ammonia gas to escape.

[0070] In some embodiments of this application, the deammoniation is carried out at a temperature above 50°C.

[0071] It is easy to understand that after adding calcium oxide or sodium hydroxide to the high-salt sulfate wastewater, ammonia can easily escape, so there is no need to remove ammonia at excessively high temperatures; ammonia removal can be fully achieved at temperatures above 50°C.

[0072] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0073] Example 1

[0074] Vanadium extraction tailings are obtained from an alumina production line. The vanadium extraction tailings contain sodium with a concentration of 88 g / L, ammonium ion concentration of 28 g / L, vanadium concentration of 0.4 g / L, and arsenic concentration of 0.5 g / L. Ammonia-reduced tailings are obtained by adding sodium hydroxide to the vanadium extraction tailings and treating them with deammoniation at 60°C. The ammonium ion concentration in the deammoniation-reduced tailings is less than 2 mg / L, and the sodium ion concentration in the solution is 122 g / L. The bauxite used in this alumina production line has an active silica content of 2%, and the solid content of the bauxite grinding slurry is 200 g / L. The amount of deammoniation tailings added per cubic meter of bauxite grinding slurry is 2.7 L. The sodium sulfate content in the circulating mother liquor is 3.8 g / L. The bauxite grinding slurry is leached at 200℃ for 5 minutes, and the sodium sulfate concentration in the leaching solution is 3.8 g / L. The sodium sulfate concentration in the leaching solution is not higher than the sodium sulfate concentration in the circulating mother liquor, indicating that all the sodium sulfate in the bauxite and deammoniation tailings has entered the red mud.

[0075] Example 2

[0076] Vanadium extraction tailings are obtained from an alumina production line. The vanadium extraction tailings contain sodium with a concentration of 88 g / L, ammonium ion concentration of 28 g / L, vanadium concentration of 0.4 g / L, and arsenic concentration of 0.5 g / L. Ammonia-reduced tailings are obtained by adding sodium hydroxide to the vanadium extraction tailings and treating them with deammoniation at 60°C. The ammonium ion concentration in the deammoniation-reduced tailings is less than 2 mg / L, and the sodium ion concentration in the solution is 122 g / L. The bauxite used in this alumina production line has an active silica content of 1%, and the solid content of the bauxite grinding slurry is 200 g / L. 2.7 L of deammoniation tailings is added per cubic meter of bauxite grinding slurry. An additional 4.9 kg of kaolin with a silica content of 45% is added to the bauxite grinding slurry. The sodium sulfate content in the circulating mother liquor is 3.8 g / L. The bauxite grinding slurry is leached at 260℃ for 30 minutes, resulting in a sodium sulfate concentration of 3.3 g / L in the leaching solution. Since the sodium sulfate concentration in the leaching solution is not higher than that in the circulating mother liquor, it is evident that all the sodium sulfate from the bauxite and deammoniation tailings has entered the red mud.

[0077] Example 3

[0078] Vanadium extraction tailings are obtained from an alumina production line. The vanadium extraction tailings contain sodium with a concentration of 88 g / L, ammonium ion concentration of 28 g / L, vanadium concentration of 0.4 g / L, and arsenic concentration of 0.5 g / L. Ammonia-reduced tailings are obtained by adding sodium hydroxide to the vanadium extraction tailings and treating them with deammoniation at 60°C. The ammonium ion concentration in the deammoniation-reduced tailings is less than 2 mg / L, and the sodium ion concentration in the solution is 122 g / L. The bauxite used in this alumina production line has an active silica content of 3%, and the solid content of the bauxite grinding slurry is 200 g / L. The amount of deammoniation tailings added per cubic meter of bauxite grinding slurry is 5.4 L. The sodium sulfate content in the circulating mother liquor is 3.8 g / L. The bauxite grinding slurry is pre-desiliconized at 90℃ for 6 hours, and then leached at 260℃. The sodium sulfate concentration in the leaching solution is 2.2 g / L. The sodium sulfate concentration in the leaching solution is not higher than the sodium sulfate concentration in the circulating mother liquor, indicating that all the sodium sulfate in the bauxite and deammoniation tailings has entered the red mud.

[0079] Example 4

[0080] Vanadium extraction tailings are obtained from an alumina production line. The vanadium extraction tailings contain sodium with a concentration of 88 g / L, ammonium ion concentration of 28 g / L, vanadium concentration of 0.4 g / L, and arsenic concentration of 0.5 g / L. Ammonia-reduced tailings are obtained by adding sodium hydroxide to the vanadium extraction tailings and treating them with deammoniation at 60°C. The ammonium ion concentration in the deammoniation-reduced tailings is less than 2 mg / L, and the sodium ion concentration in the solution is 122 g / L. The bauxite used in this alumina production line has an active silica content of 3%, and the solid content of the bauxite grinding slurry is 200 g / L. The amount of deammoniation tailings added per cubic meter of bauxite grinding slurry is 10.8 L, and 2.2 kg of silica is added. The sodium sulfate content in the circulating mother liquor is 3.8 g / L. The bauxite grinding slurry is leached at 260℃, and the sodium sulfate concentration in the leaching solution is 3.2 g / L. The sodium sulfate concentration in the leaching solution is not higher than the sodium sulfate concentration in the circulating mother liquor, indicating that all the sodium sulfate in the bauxite and deammoniation tailings has entered the red mud.

[0081] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0082] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. For associations involving three or more related objects described using "and / or", it indicates that any one of the three related objects can exist alone, or at least two of them can exist simultaneously. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0083] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for treating high-salinity sulfate wastewater, characterized in that, The method for treating high-salt sulfate wastewater includes the following steps: Provide high-salt sulfate wastewater, which is the tail liquid from vanadium extraction in the Bayer process for alumina production; The high-salt sulfate wastewater was subjected to ammonia removal treatment to obtain ammonia removal tailings. The deammoniation tailings are sent to the bauxite grinding process, so that the deammoniation tailings are finally incorporated into the slurry formed by bauxite grinding. Determine whether the total silicon-sulfur ratio of the deammoniation tailings and bauxite in the grinding process reaches 6 or above. If the silicon-sulfur ratio does not reach 6 or above, add raw materials containing silicon dioxide to the bauxite until the silicon-sulfur ratio reaches 6 or above. The deammoniation tailings are ultimately fed into the slurry formed by bauxite grinding; The slurry is subjected to leaching treatment; The solid content of the slurry is 180~220g / L, and the amount of the deammoniation tailings that is finally fed into the slurry formed by grinding bauxite is 2~15L per cubic meter of slurry; the leaching temperature is above 200℃; and the leaching treatment time is above 5min.

2. The method for treating high-salinity sulfate wastewater according to claim 1, characterized in that, The method for treating high-salt sulfate wastewater further includes the following steps: Determine whether the total silicon-sulfur ratio of the deammoniation tailings and bauxite in the grinding process reaches 4 or above. If the silicon-sulfur ratio does not reach 4 or above, add raw materials containing silicon dioxide to the bauxite until the silicon-sulfur ratio reaches 4 or above. The deammoniation tailings are ultimately fed into the slurry formed by bauxite grinding; The slurry is subjected to pre-desiliconization treatment; The slurry after pre-desiliconization treatment is subjected to leaching treatment.

3. The method for treating high-salinity sulfate wastewater according to claim 1, characterized in that, The silica-containing raw materials include at least one of the following: low-grade bauxite, kaolin, glass, chlorite, diatomite, and silica molecular sieve.

4. The method for treating high-salinity sulfate wastewater according to claim 1, characterized in that, The method for treating high-salt sulfate wastewater further includes the following steps: Ammonium sulfate is obtained by absorbing the ammonia gas obtained from the deamination with dilute sulfuric acid. The ammonium sulfate is then returned to the vanadium extraction step in the alumina preparation process.

5. The method for treating high-salinity sulfate wastewater according to claim 1, characterized in that, The deamination method is as follows: Add calcium oxide or sodium hydroxide to the high-salt sulfate wastewater to allow ammonia gas to escape.

6. The method for treating high-salinity sulfate wastewater according to claim 1, characterized in that, The deamination is carried out at a temperature above 50°C.

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