A method for treating arsenic-containing tailings
By mixing arsenic-containing tailings into bauxite and leaching it, hydroxyapatite is generated, which solves the economic and toxicity problems of arsenic-containing tailings treatment and realizes the safe discharge of harmful elements and the recycling of valuable elements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHENGZHOU NON FERROUS METALS RES INST CO LTD OF CHALCO
- Filing Date
- 2024-10-12
- Publication Date
- 2026-07-07
AI Technical Summary
Existing methods for treating arsenic-containing tailings are uneconomical and have complex processes. Furthermore, the leaching toxicity of arsenic-containing tailings exceeds the national standards for hazardous waste identification, making them difficult to treat effectively.
Arsenic-containing tailings are mixed into bauxite, and the mixture is ground into a slurry and then leached to enrich phosphorus, arsenic, and fluorine elements into the red mud. Phosphorus reacts with calcium to form hydroxyapatite, and arsenic and fluorine elements are interspersed in the crystal lattice. The solid leaching toxicity of the red mud meets the national standards.
It has achieved safe treatment of arsenic-containing tailings, reduced its leaching toxicity, met the national standards for hazardous waste, and enabled the recycling of valuable elements such as vanadium, simplifying the process and reducing costs.
Smart Images
Figure CN119237447B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of environmental protection, and in particular to the treatment of industrial waste. Background Technology
[0002] In the low-temperature Bayer process for alumina production, especially when using high-vanadium bauxite, vanadium accumulates in the alumina production system, leading to problems such as finer product particle size and decreased decomposition rate. Vanadium itself is also a resource with high economic value. To recover vanadium, low-temperature crystallization is currently the commonly used method for vanadium removal. However, while vanadium crystallizes and precipitates as vanadium slag, impurities such as phosphorus, fluorine, and arsenic are also precipitated from the alumina production system. Extracting vanadium from vanadium slag requires first removing these impurities. Currently, the removal of phosphorus, arsenic, and fluorine is generally carried out using hydrothermal methods. After hydrothermal treatment of vanadium slag, arsenic-containing tailings are formed, enriched with phosphorus, arsenic, and fluorine. These tailings have poor crystallinity, and phosphorus, arsenic, and fluorine are easily leached, resulting in leaching toxicity exceeding the national hazardous waste identification standards, posing a significant hazard. Currently, the disposal of arsenic-containing tailings often employs methods such as high-temperature sintering, cement solidification, and geopolymer solidification. These methods are uneconomical, have complex processes, and significantly reduce the efficiency of vanadium extraction. Summary of the Invention
[0003] This application provides a method for treating arsenic-containing tailings to solve the technical problems of poor economic efficiency and complex process flow in the treatment of arsenic-containing tailings.
[0004] This application provides a method for treating arsenic-containing tailings, the method comprising:
[0005] Obtain arsenic-containing tailings from the alumina preparation process;
[0006] The arsenic-containing tailings were mixed into bauxite;
[0007] The bauxite is ground into a slurry;
[0008] The slurry is subjected to leaching treatment, which enriches the phosphorus, arsenic, and fluorine elements in the arsenic-containing tailings into the red mud formed by the leaching treatment.
[0009] In some embodiments of this application, the arsenic-containing tailings are mixed into bauxite, and the arsenic-containing tailings mixed into the bauxite account for 0 to 100% of the mass of the bauxite.
[0010] In some embodiments of this application, the arsenic-containing tailings are mixed into bauxite, wherein the arsenic-containing tailings mixed into the bauxite account for 70-100% of the mass of the bauxite.
[0011] In some embodiments of this application, the leaching temperature is above 145°C.
[0012] In some embodiments of this application, the dissolution time is 5 minutes or more.
[0013] In some embodiments of this application, the arsenic-containing tailings are formed by adding a decontaminant to the vanadium extraction tailings after vanadium extraction and precipitation. The decontaminant is at least one of calcium-based, iron-based, aluminum-based, and magnesium-based decontaminants.
[0014] In some embodiments of this application, the impurity remover is at least one of calcium sulfate, calcium oxalate, ferric sulfate, aluminum sulfate, magnesium sulfate, and magnesium bicarbonate.
[0015] In some embodiments of this application, the impurity remover is at least one selected from iron-based, aluminum-based, and magnesium-based impurity removers.
[0016] During the leaching process, quicklime is also added to the slurry.
[0017] In some embodiments of this application, the total molar amount of additional quicklime is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings.
[0018] The technical solutions provided in this application have the following advantages compared with the prior art:
[0019] The method for treating arsenic-containing tailings provided in this application involves mixing the arsenic-containing tailings with bauxite and then using the bauxite for alumina production. Phosphorus reacts with calcium to form hydroxyapatite, allowing phosphorus to be discharged along with the red mud. Arsenic and fluorine are continuously discharged by utilizing the phenomenon of arsenic and fluorine inclusions within the hydroxyapatite lattice, and the resulting red mud has a solid leaching toxicity that meets national standards for hazardous waste. This application enriches the originally harmful elements in the arsenic-containing tailings into the red mud for storage, solving the technical problem of the difficulty in treating arsenic-containing tailings. This application also achieves the recycling of substances such as vanadium in the arsenic-containing tailings. Attached Figure Description
[0020] 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.
[0021] 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.
[0022] Figure 1 This is a schematic flowchart illustrating a method for treating arsenic-containing tailings provided in an embodiment of this application. Detailed Implementation
[0023] 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.
[0024] 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.
[0025] 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.
[0026] Existing methods for treating arsenic-containing tailings suffer from poor economic efficiency and complex processes.
[0027] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:
[0028] This application provides a method for treating arsenic-containing tailings, the method comprising:
[0029] S1: Obtain arsenic-containing tailings from the alumina preparation process;
[0030] S2: Mix the arsenic-containing tailings into bauxite;
[0031] S3: Grind the bauxite to prepare a slurry;
[0032] S4: The slurry is subjected to leaching treatment, so that the phosphorus, arsenic and fluorine elements in the arsenic-containing tailings are enriched in the red mud formed by the leaching treatment.
[0033] It is easy to understand that grinding bauxite into a slurry and then leaching the slurry is the standard process for the Bayer process to produce alumina.
[0034] This application mixes the arsenic-containing tailings with bauxite. During the leaching process, phosphorus and calcium in the arsenic-containing tailings react to form hydroxyapatite, which precipitates as part of the red mud. A portion of the arsenic and fluorine in the tailings enters the sodium aluminate solution in the alumina process. Finally, during the vanadium removal process in the alumina process, as vanadium slag precipitates, it is enriched back into the arsenic-containing tailings after vanadium extraction. This arsenic-containing tailings then mixes with the bauxite, and this portion of arsenic and fluorine re-enters the alumina-bauxite leaching process. Another portion of the arsenic and fluorine is trapped between the hydroxyapatite crystals and enters the red mud. The solid leaching toxicity of the red mud meets the national standards for hazardous waste, and the red mud is ultimately stored in a red mud dump. Therefore, although a portion of the arsenic and fluorine in the tailings is recycled back to the bauxite leaching process, another portion is continuously discharged from the system along with the red mud, ultimately ensuring that the arsenic and fluorine content in the entire Bayer process for alumina production is not too high and thus does not affect alumina production.
[0035] It is easy to understand that arsenic-containing tailings also contain small amounts of reusable substances, such as vanadium and some sodium. By mixing the arsenic-containing tailings with bauxite, these substances can be reused.
[0036] This application involves mixing arsenic-containing tailings with bauxite and then using the bauxite for alumina production. Phosphorus reacts with calcium to form hydroxyapatite, allowing phosphorus to be discharged along with the red mud. Arsenic and fluorine are continuously removed by utilizing the inclusion of these elements within the hydroxyapatite lattice. Furthermore, the solid leaching toxicity of the resulting red mud meets national standards for hazardous waste. This application enriches the originally harmful elements in the arsenic-containing tailings within the red mud for storage, solving the technical problem of the difficulty in treating arsenic-containing tailings. This application also achieves the recycling of substances such as vanadium in the arsenic-containing tailings.
[0037] In some embodiments of this application, the arsenic-containing tailings are mixed into bauxite, wherein the arsenic-containing tailings mixed into the bauxite account for 0.1% to 100% of the mass of the bauxite.
[0038] It should be noted that during the leaching process, red mud has an extremely strong ability to enrich phosphorus, arsenic, and fluorine, and these elements exist very stably in red mud. Therefore, even if a large amount of arsenic-containing tailings is mixed into the bauxite, for example, if the arsenic-containing tailings account for 100% of the bauxite mass, it will not affect the purity of aluminum hydroxide crystallization in subsequent steps of the Bayer process, nor will it cause the leaching toxicity of the red mud to exceed the standard. Typically, the arsenic-containing tailings produced by the Bayer process are much less than the bauxite consumed. Therefore, the arsenic-containing tailings can be mixed into bauxite in small amounts multiple times depending on the actual situation, or the mixing frequency can be reduced, and bauxite can be mixed in only after a large amount has accumulated.
[0039] In some embodiments of this application, the arsenic-containing tailings are mixed into bauxite, wherein the arsenic-containing tailings mixed into the bauxite account for 70-100% of the mass of the bauxite.
[0040] Introducing a large amount of arsenic-containing tailings into bauxite at once necessitates adding more circulating mother liquor during bauxite grinding to ensure adequate slurry concentration and thorough grinding of the bauxite. However, the output of arsenic-containing tailings is very small compared to the consumption of bauxite. Therefore, after a large-scale incorporation of arsenic-containing tailings, there will be a prolonged period without its addition, resulting in reduced circulating mother liquor usage during bauxite grinding. This leads to fluctuations in the overall circulating mother liquor consumption, but incorporating large quantities of arsenic-containing tailings in smaller, more frequent incorporations saves considerable labor. Therefore, under normal circumstances, if the plant has the capacity to store arsenic-containing tailings, this method of incorporating large quantities in smaller, more frequent incorporations can be considered.
[0041] In some embodiments of this application, the leaching temperature is above 145°C.
[0042] It is easy to understand that the beneficial effect of the leaching temperature of 145°C or higher is that it allows the alumina in the bauxite to dissolve completely, and allows the phosphorus to react fully with the calcium to form hydroxyapatite.
[0043] In some embodiments of this application, the dissolution time is 5 minutes or more.
[0044] It is easy to understand that the beneficial effect of the dissolution time of more than 5 minutes is that it allows the alumina in the bauxite to dissolve completely, and allows the phosphorus to react fully with the calcium to form hydroxyapatite.
[0045] In some embodiments of this application, the arsenic-containing tailings are formed by adding a decontaminant to the vanadium extraction tailings after vanadium extraction and precipitation. The decontaminant is at least one of calcium-based, iron-based, aluminum-based, and magnesium-based decontaminants.
[0046] It is readily understood that the calcium-based impurity remover refers to a salt substance that can ionize calcium ions in an aqueous solution without introducing other impurity anions. In some embodiments of this application, the calcium-based impurity remover may be at least one of calcium sulfate and calcium oxalate.
[0047] It is readily understood that the iron-based impurity remover refers to a salt substance that can ionize iron ions in an aqueous solution without introducing other impurity anions. In some embodiments of this application, the iron-based impurity remover may be ferric sulfate.
[0048] It is readily understood that the aluminum-based impurity remover refers to a salt substance that can ionize calcium ions in aqueous solution without introducing other impurity anions. In some embodiments of this application, the aluminum-based impurity remover may be aluminum sulfate.
[0049] It is readily understood that the magnesium-based impurity remover refers to a salt substance that can ionize calcium ions in aqueous solution without introducing other impurity anions. In some embodiments of this application, the magnesium-based impurity remover may be at least one of magnesium sulfate and magnesium bicarbonate.
[0050] In some embodiments of this application, the impurity remover is at least one selected from iron-based, aluminum-based, and magnesium-based impurity removers.
[0051] During the leaching process, quicklime is also added to the slurry.
[0052] It is readily understood that, provided the impurity remover is at least one of iron-based, aluminum-based, or magnesium-based impurity removers, quicklime should be added during the leaching process to supplement calcium ions into the slurry, ensuring sufficient formation of hydroxyapatite from phosphorus. When the impurity remover is calcium-based, it is not necessary to add quicklime during the leaching process.
[0053] In some embodiments of this application, the total molar amount of additional quicklime is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings.
[0054] The purpose of adding an extra amount of quicklime, which is more than twice the total amount of arsenic and fluorine in the arsenic-containing tailings, is to ensure that the vast majority of arsenic and fluorine can be incorporated into the hydroxyapatite.
[0055] 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.
[0056] Example 1
[0057] In this embodiment, arsenic-containing tailings formed using a calcium-based impurity remover are selected. These tailings are mixed into bauxite at a concentration of 0.1% of the bauxite mass. The bauxite is then ground into a slurry, which is subsequently subjected to leaching treatment. This process enriches the phosphorus, arsenic, and fluorine elements in the arsenic-containing tailings into the red mud formed by the leaching treatment. The leaching temperature is 260℃, and the leaching time is 5 minutes. Before treatment, the leaching toxicity of the arsenic-containing tailings was 19.94 mg / L for As and 5.25 mg / L for F. After leaching treatment, the leaching toxicity of the red mud was 2.2 mg / L for As and 2.6 mg / L for F.
[0058] In this embodiment, the method for determining the leaching toxicity of solid waste is the sulfuric acid-nitric acid method.
[0059] Example 2
[0060] In this embodiment, arsenic-containing tailings formed using a calcium-based impurity remover were selected. 10g of this arsenic-containing tailings was mixed into bauxite, representing 50% of the bauxite's mass. The bauxite was then ground into a slurry, which was subsequently subjected to leaching treatment. This process enriched the phosphorus, arsenic, and fluorine elements in the arsenic-containing tailings into the red mud formed by the leaching treatment. The leaching temperature was 260℃, and the leaching time was 30 minutes. Before treatment, the leaching toxicity of the arsenic-containing tailings was 19.94 mg / L for As and 5.25 mg / L for F. After leaching treatment, the concentrations of vanadium, fluorine, and arsenic in the leaching solution were 0.28 g / L, 1.40 g / L, and 0.42 g / L, respectively. The leaching toxicity of the red mud was 1.5 mg / L for As and 1.2 mg / L for F.
[0061] In this embodiment, the method for determining the leaching toxicity of solid waste is the sulfuric acid-nitric acid method.
[0062] Example 3
[0063] In this embodiment, arsenic-containing tailings formed by an aluminum-based impurity remover were selected. 10g of the arsenic-containing tailings was mixed into bauxite, accounting for 50% of the bauxite mass. The bauxite was then ground into a slurry, which was subsequently subjected to leaching treatment. This process enriched the phosphorus, arsenic, and fluorine elements in the arsenic-containing tailings into the red mud formed by the leaching treatment. The leaching temperature was 260℃, and the leaching time was 30 minutes. Before treatment, the leaching toxicity of the arsenic-containing tailings was As: 220 mg / L, F: 21.1 mg / L. The mother liquor volume was 100 mL, and the concentrations of vanadium, arsenic, and fluorine in the mother liquor were 0.43 g / L, 0.49 g / L, and 1.2 g / L, respectively. Lime was added during the leaching process, and the amount of lime added was twice the total molar amount of arsenic and fluorine in the tailings. After leaching treatment, the concentration of vanadium in the leaching solution was 0.48 g / L, the concentration of arsenic was 0.22 g / L, and the concentration of fluorine was 1.5 g / L. The leaching toxicity of the red mud was As: 1.7 mg / L and F: 1.7 mg / L.
[0064] In this embodiment, the method for determining the leaching toxicity of solid waste is the sulfuric acid-nitric acid method.
[0065] Comparative Example 1
[0066] 10g of bauxite was leached at a leaching temperature of 260℃ for 30min. After leaching, the concentration of vanadium in the leaching solution was 0.074g / L, the concentration of fluorine was 1.33g / L, and the concentration of arsenic was undetectable. The leaching toxicity of the red mud was As: 3.7mg / L and F: 5.1mg / L.
[0067] The method for determining the leaching toxicity of solid waste in this comparative example was the sulfuric acid-nitric acid method.
[0068] Comparative Example 2
[0069] This comparative example uses arsenic-containing tailings formed with a calcium-based impurity remover. The arsenic-containing tailings are treated separately, ground into a slurry, and then subjected to leaching treatment at 145℃ for 5 minutes. Before treatment, the leaching toxicity of the arsenic-containing tailings was As: 19.94 mg / L, F: 5.25 mg / L, and the concentration of vanadium, arsenic, and fluorine in the mother liquor was 0.43 g / L, 0.49 g / L, and 1.2 g / L. After leaching treatment, the concentration of vanadium in the leaching solution was 0.96 g / L, arsenic concentration was 1.7 g / L, and fluorine concentration was 1.4 g / L. The leaching toxicity of the remaining solids was As: 1.5 mg / L, F: 3.5 mg / L.
[0070] The method for determining the leaching toxicity of solid waste in this comparative example was the sulfuric acid-nitric acid method.
[0071] 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.
[0072] 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 entity or operation, 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.
[0073] 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 arsenic-containing tailings, characterized in that, The method for treating the arsenic-containing tailings includes: Arsenic-containing tailings are obtained from the low-temperature Bayer process for alumina production. The arsenic-containing tailings are formed by adding a purification agent to the vanadium extraction tail liquid after vanadium extraction and precipitation, resulting in arsenic-containing tailings enriched with phosphorus, arsenic and fluorine elements. The arsenic-containing tailings are mixed with bauxite to form a bauxite mixture; The bauxite mixture is ground to prepare a slurry; The slurry is subjected to leaching treatment to enrich the phosphorus, arsenic, and fluorine elements in the arsenic-containing tailings into the red mud formed by the leaching treatment. The leaching temperature is above 145°C and the leaching time is above 5 minutes.
2. The method for treating arsenic-containing tailings according to claim 1, characterized in that, The impurity remover is at least one of calcium-based, iron-based, aluminum-based, and magnesium-based impurity removers.
3. The method for treating arsenic-containing tailings according to claim 2, characterized in that, The impurity removal agent is at least one of calcium sulfate, calcium oxalate, ferric sulfate, aluminum sulfate, magnesium sulfate, and magnesium bicarbonate.
4. The method for treating arsenic-containing tailings according to claim 2, characterized in that, The impurity remover is at least one of iron-based, aluminum-based, and magnesium-based impurity removers. During the leaching process, quicklime is also added to the slurry.
5. The method for treating arsenic-containing tailings according to claim 4, characterized in that, The total molar amount of the additional quicklime is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings.