Treatment method of arsenic-containing tailings

Abstract

The invention relates to a treatment method for arsenic-containing tailings. The treatment method for the arsenic-containing tailings comprises the steps that the arsenic-containing tailings of an aluminum oxide preparation process are obtained; mixing the arsenic-containing tailings into bauxite; the bauxite is ground into ore pulp; and the ore pulp is subjected to dissolution treatment, so that phosphorus, arsenic and fluorine elements in the arsenic-containing tailings are enriched into red mud formed through dissolution treatment. Original harmful elements of the arsenic-containing tailings are enriched into the red mud to be piled up, and the technical problem that the arsenic-containing tailings are difficult to treat is solved. And meanwhile, cyclic utilization of substances such as the vanadium element in the arsenic-containing tailings is achieved.

Description

Technical Field

[0001] The present application relates to the field of environmental protection, and in particular to industrial waste treatment. Background Art

[0002] In the process of producing alumina by the low-temperature Bayer process, especially in the process of using high-vanadium bauxite, vanadium accumulates in the alumina production system, resulting in problems such as product particle size refinement and decreased decomposition rate, and vanadium itself is also a resource with high economic value. In order to recover vanadium, low-temperature crystallization is generally used to remove vanadium at this stage. While vanadium crystallization is precipitated to obtain vanadium slag, impurities such as phosphorus, fluorine, and arsenic are also precipitated in the alumina production system. To extract vanadium from vanadium slag, impurities such as phosphorus, arsenic, and fluorine need to be removed first. At present, the removal of impurities such as phosphorus, arsenic, and fluorine is generally carried out by hydrothermal method. After the vanadium slag is treated by hydrothermal method, arsenic-containing tailings enriched with phosphorus, arsenic, and fluorine elements will be formed. The crystallinity of arsenic-containing tailings is poor, and phosphorus, arsenic, and fluorine are easily leached, which leads to the leaching toxicity of arsenic-containing tailings higher than the national hazardous waste identification standard, which is highly harmful. At present, the disposal of arsenic-containing tailings often adopts methods such as high-temperature sintering, cement solidification, and geopolymer solidification. These methods are poor in economic efficiency and complex in process flow, which greatly reduces the efficiency of vanadium extraction. Summary of the invention

[0003] The embodiment of the present application provides a method for treating arsenic-containing tailings to solve the technical problems of poor economy and complicated process flow in the method for treating arsenic-containing tailings.

[0004] The present application provides a method for treating arsenic-containing tailings, and the method for treating arsenic-containing tailings includes:

[0005] Obtaining arsenic-containing tailings from the alumina production process;

[0006] mixing the arsenic-containing tailings into bauxite;

[0007] Grinding the bauxite to form a slurry;

[0008] The ore pulp is subjected to a dissolution treatment so that the phosphorus, arsenic and fluorine elements in the arsenic-containing tailings are enriched in the red mud formed by the dissolution treatment.

[0009] In some embodiments of the present 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 the present application, the arsenic-containing tailings are mixed into bauxite, and the arsenic-containing tailings mixed into the bauxite account for 70-100% of the mass of the bauxite.

[0011] In some embodiments of the present application, the dissolution temperature is above 145°C.

[0012] In some embodiments of the present application, the dissolution time is more than 5 minutes.

[0013] In some embodiments of the present application, the arsenic-containing tailings are formed by adding an impurity remover to the vanadium extraction tail liquid after vanadium extraction from the vanadium slag, and the impurity remover is at least one of a calcium-based impurity remover, an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover.

[0014] In some embodiments of the present application, the impurity remover is at least one of calcium sulfate, calcium oxalate, iron sulfate, aluminum sulfate, magnesium sulfate, and magnesium bicarbonate.

[0015] In some embodiments of the present application, the impurity remover is at least one of an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover.

[0016] During the dissolution treatment, quicklime is additionally added to the slurry.

[0017] In some embodiments of the present application, the total molar amount of quicklime added additionally is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The method for treating arsenic-containing tailings provided in the embodiment of the present application is to mix the arsenic-containing tailings with bauxite and then select the bauxite for alumina production, utilize phosphorus and calcium to react to generate hydroxyapatite, so that the phosphorus element is discharged along with the red mud; utilize the phenomenon that arsenic and fluorine elements are mixed in the hydroxyapatite lattice to continuously discharge arsenic and fluorine elements, and the solid leaching toxicity of the obtained red mud meets the national standard requirements for hazardous waste. The present application enriches the harmful elements originally in the arsenic-containing tailings into red mud for storage, solving the technical problem that the arsenic-containing tailings are difficult to treat. The present application also realizes the recycling of substances such as vanadium elements in the arsenic-containing tailings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic flow chart of a method for treating arsenic-containing tailings provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] Unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the event of a conflict, this specification takes precedence.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0026] The existing treatment methods for arsenic-containing tailings have technical problems such as poor economy and complicated process flow.

[0027] The technical solution provided by the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0028] The present application provides a method for treating arsenic-containing tailings, and the method for treating arsenic-containing tailings includes:

[0029] S1: Obtain arsenic-containing tailings from the alumina preparation process;

[0030] S2: mixing the arsenic-containing tailings into bauxite;

[0031] S3: Grinding the bauxite to form a slurry;

[0032] S4: performing a dissolution treatment on the ore pulp, so that the phosphorus, arsenic and fluorine elements in the arsenic-containing tailings are enriched in the red mud formed by the dissolution treatment.

[0033] It is easy to understand that grinding bauxite into slurry and then dissolving the slurry is the conventional process of preparing alumina by the Bayer process.

[0034] The present application mixes the arsenic-containing tailings into bauxite. During the dissolution process, the phosphorus in the arsenic-containing tailings reacts with calcium to form hydroxyapatite, and the hydroxyapatite forms a precipitate as part of the red mud; part of the arsenic and fluorine in the arsenic-containing tailings will enter the sodium aluminate solution of the alumina process, and finally in the vanadium removal process of the alumina process, with the precipitation of vanadium slag, and then enriched in the arsenic-containing tailings after vanadium extraction, and the arsenic-containing tailings are mixed with bauxite again, and this part of arsenic and fluorine will re-enter the alumina bauxite dissolution process; while the other part of arsenic and fluorine will be sandwiched between the hydroxyapatite lattices and enter the red mud, and the solid leaching toxicity of the red mud meets the national standard requirements for hazardous waste, and finally the red mud enters the red mud dump for storage. Therefore, although part of the arsenic and fluorine in the arsenic-containing tailings will be recycled back to the bauxite dissolution process, the other part of the arsenic and fluorine will be continuously discharged from the system with the efflux of the red mud, and finally the arsenic and fluorine content in the entire Bayer process of alumina will not be too high to affect the production of alumina.

[0035] It is easy to understand that the arsenic-containing tailings also contain a small amount of recyclable substances, such as vanadium, a portion of sodium, etc. By mixing the arsenic-containing tailings into bauxite, these substances can be reused.

[0036] The present application mixes arsenic-containing tailings into bauxite and then uses the bauxite to produce alumina, utilizes the reaction of phosphorus and calcium to generate hydroxyapatite, and discharges the phosphorus element along with the red mud; utilizes the phenomenon that arsenic and fluorine elements are mixed in the hydroxyapatite lattice to continuously discharge the arsenic and fluorine elements, and the solid leaching toxicity of the obtained red mud meets the national standard requirements for hazardous waste. The present application enriches the harmful elements originally in the arsenic-containing tailings into the red mud for storage, solving the technical problem that the arsenic-containing tailings are difficult to handle. The present application also realizes the recycling of substances such as vanadium elements in the arsenic-containing tailings.

[0037] In some embodiments of the present application, the arsenic-containing tailings are mixed into bauxite, and 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 dissolution treatment process, red mud has a strong ability to enrich phosphorus, arsenic, and fluorine, and phosphorus, arsenic, and fluorine can exist very stably in red mud. Therefore, even if a large amount of arsenic-containing tailings are mixed into bauxite, for example, the arsenic-containing tailings mixed into bauxite account for 100% of the mass of the bauxite, it will not affect the purity of aluminum hydroxide crystals in the subsequent steps of the Bayer process, and will not cause the leaching toxicity of red mud to exceed the standard. Usually, the arsenic-containing tailings produced by the Bayer process are much less than the bauxite consumed, so the arsenic-containing tailings can be mixed into bauxite in small quantities for multiple times according to actual conditions, or the mixing frequency can be reduced, and mixed into bauxite after a large amount of accumulation.

[0039] In some embodiments of the present application, the arsenic-containing tailings are mixed into bauxite, and the arsenic-containing tailings mixed into the bauxite account for 70-100% of the mass of the bauxite.

[0040] If a large amount of arsenic-containing tailings is mixed into the bauxite at one time, more circulating mother liquor needs to be added to ensure that the concentration of the slurry is appropriate in order to ensure that the bauxite is fully ground when the bauxite is ground. However, the output of arsenic-containing tailings is very small compared to the consumption of bauxite. Therefore, after a large amount of arsenic-containing tailings is mixed in at one time, there will be a long period of time without arsenic-containing tailings mixed in, and the circulating mother liquor added to the bauxite during grinding will be reduced. This will generally cause fluctuations in the amount of circulating mother liquor, but mixing arsenic-containing tailings in small amounts can save a lot of labor. Therefore, under normal circumstances, as long as the factory has the conditions to store arsenic-containing tailings, it can consider adopting a small amount of large mixing method.

[0041] In some embodiments of the present application, the dissolution temperature is above 145°C.

[0042] It is easy to understand that the beneficial effect of the dissolution temperature being above 145° C. is that the aluminum oxide in the bauxite is completely dissolved at the same time, and phosphorus is fully reacted with calcium to form hydroxyapatite.

[0043] In some embodiments of the present application, the dissolution time is more than 5 minutes.

[0044] It is easy to understand that the beneficial effect of the dissolution time being more than 5 minutes is that the aluminum oxide in the bauxite is completely dissolved at the same time, and the phosphorus fully reacts with calcium to form hydroxyapatite.

[0045] In some embodiments of the present application, the arsenic-containing tailings are formed by adding an impurity remover to the vanadium extraction tail liquid for precipitation after vanadium extraction from the vanadium slag, and the impurity remover is at least one of a calcium-based impurity remover, an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover.

[0046] It is easy to understand 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 the present application, the calcium-based impurity remover can be at least one of calcium sulfate and calcium oxalate.

[0047] It is easy to understand 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 the present application, the iron-based impurity remover can be ferric sulfate.

[0048] It is easy to understand that the aluminum-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 the present application, the aluminum-based impurity remover can be aluminum sulfate.

[0049] It is easy to understand that the magnesium-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 the present application, the magnesium-based impurity remover can be at least one of magnesium sulfate and magnesium bicarbonate.

[0050] In some embodiments of the present application, the impurity remover is at least one of an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover.

[0051] During the dissolution treatment, quicklime is additionally added to the slurry.

[0052] It is easy to understand that, under the premise that the impurity remover is at least one of an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover, quicklime should be additionally added during the dissolution process to add calcium ions to the slurry so that the phosphorus element can fully form hydroxyapatite. When the impurity remover is a calcium-based impurity remover, it is not necessary to additionally add quicklime to the dissolution process.

[0053] In some embodiments of the present application, the total molar amount of quicklime added additionally is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings.

[0054] The total molar amount of quicklime added additionally is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings in order to ensure that most of the arsenic and fluorine can be mixed into the hydroxyapatite.

[0055] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0056] Example 1

[0057] In this embodiment, arsenic-containing tailings formed by calcium-based impurity removers are selected, and the arsenic-containing tailings are mixed into bauxite, and the mixing amount accounts for 0.1% of the mass of the bauxite. Subsequently, the bauxite is ground into slurry, and the slurry is subjected to dissolution treatment, so that the phosphorus, arsenic, and fluorine elements in the arsenic-containing tailings are enriched in the red mud formed by the dissolution treatment, wherein the dissolution temperature is 260°C and the dissolution time is 5 minutes. The leaching toxicity of the arsenic-containing tailings before treatment is As: 19.94 mg / L, F: 5.25 mg / L. After the dissolution treatment, the leaching toxicity of the red mud is As: 2.2 mg / L, F: 2.6 mg / L.

[0058] The solid waste leaching toxicity determination method in this embodiment is the sulfuric acid and nitric acid method.

[0059] Example 2

[0060] In this embodiment, arsenic-containing tailings formed by calcium-based impurity removers are selected, and 10g of the arsenic-containing tailings are mixed into bauxite, and the mixing amount accounts for 50% of the mass of the bauxite. Subsequently, the bauxite is ground into slurry, and the slurry is subjected to dissolution treatment to enrich the phosphorus, arsenic and fluorine elements in the arsenic-containing tailings into the red mud formed by the dissolution treatment, wherein the dissolution temperature is 260°C and the dissolution time is 30min. The leaching toxicity of the arsenic-containing tailings before treatment is As: 19.94mg / L, F: 5.25mg / L. After dissolution treatment, the vanadium concentration in the dissolution solution is 0.28g / L, the fluorine concentration is 1.40g / L, and the arsenic concentration is 0.42g / L, and the leaching toxicity of the red mud is As: 1.5mg / L, F: 1.2mg / L.

[0061] The solid waste leaching toxicity determination method in this embodiment is the sulfuric acid and nitric acid method.

[0062] Example 3

[0063] In this embodiment, arsenic-containing tailings formed by aluminum-based impurity removers are selected, 10g of the arsenic-containing tailings are mixed into bauxite, and the mixing amount accounts for 50% of the mass of the bauxite. Subsequently, the bauxite is ground into slurry, and the slurry is subjected to dissolution treatment to enrich the phosphorus, arsenic and fluorine elements in the arsenic-containing tailings into the red mud formed by the dissolution treatment, wherein the dissolution temperature is 260°C and the dissolution time is 30min. The leaching toxicity of the arsenic-containing tailings before treatment is As: 220mg / L, F: 21.1mg / L, the amount of mother liquor is 100mL, and the vanadium concentration in the mother liquor is 0.43g / L, the arsenic concentration is 0.49g / L, and the fluorine concentration is 1.2g / L. Lime is added during the dissolution process. The amount of lime added is twice the total molar amount of arsenic and fluorine in the tailings. After dissolution treatment, the vanadium concentration in the dissolution solution is 0.48g / L, the arsenic concentration is 0.22g / L, and the fluorine concentration is 1.5g / L. The leaching toxicity of the red mud is As: 1.7mg / L, F: 1.7mg / L.

[0064] The solid waste leaching toxicity determination method in this embodiment is the sulfuric acid and nitric acid method.

[0065] Comparative Example 1

[0066] 10g of bauxite was dissolved at a dissolution temperature of 260℃ and a dissolution time of 30min. After the dissolution treatment, the vanadium concentration in the dissolution solution was 0.074g / L, the fluorine concentration was 1.33g / L, and the arsenic concentration was undetectable. The leaching toxicity of the red mud was As: 3.7mg / L, F: 5.1mg / L.

[0067] The leaching toxicity of the solid waste in this comparative example was determined by the sulfuric acid and nitric acid method.

[0068] Comparative Example 2

[0069] In this comparative example, arsenic-containing tailings formed by a calcium-based impurity remover are selected, and the arsenic-containing tailings are treated separately. After the arsenic-containing tailings are ground into slurry, the slurry is subjected to dissolution treatment, wherein the dissolution temperature is 145°C and the dissolution time is 5 minutes. The leaching toxicity of the arsenic-containing tailings before treatment is As: 19.94 mg / L, F: 5.25 mg / L, the vanadium concentration in the mother liquor is 0.43 g / L, the arsenic concentration is 0.49 g / L, and the fluorine concentration is 1.2 g / L. After dissolution treatment, the vanadium concentration in the dissolution liquid is 0.96 g / L, the arsenic concentration is 1.7 g / L, and the fluorine concentration is 1.4 g / L, and the leaching toxicity of the remaining solids is As: 1.5 mg / L, F: 3.5 mg / L.

[0070] The leaching toxicity of the solid waste in this comparative example was determined by the sulfuric acid and nitric acid method.

[0071] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0072] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. refer to "including but not limited to". Moreover, the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of these three associated objects can exist alone, or any at least two of them exist at the same time. For example, for A, and / or B, and / or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, wherein a, b, and c can be single or multiple, respectively.

[0073] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for treating arsenic-containing tailings, characterized in that: The method for treating arsenic-containing tailings comprises: Obtaining arsenic-containing tailings from the alumina production process; mixing the arsenic-containing tailings into bauxite; Grinding the bauxite to form a slurry; The ore pulp is subjected to a dissolution treatment so that the phosphorus, arsenic and fluorine elements in the arsenic-containing tailings are enriched in the red mud formed by the dissolution treatment.

2. The method for treating arsenic-containing tailings according to claim 1, characterized in that: The arsenic-containing tailings are mixed into bauxite, and the arsenic-containing tailings mixed into the bauxite account for 0.1% to 100% of the mass of the bauxite.

3. The method for treating arsenic-containing tailings according to claim 2, characterized in that: The arsenic-containing tailings are mixed into bauxite, and the arsenic-containing tailings mixed into the bauxite account for 70% to 100% of the mass of the bauxite.

4. The method for treating arsenic-containing tailings according to claim 1, characterized in that: The dissolution temperature is 145° C. or higher.

5. The method for treating arsenic-containing tailings according to claim 1, characterized in that: The dissolution time is more than 5 minutes.

6. The method for treating arsenic-containing tailings according to claim 1, characterized in that: The arsenic-containing tailings are formed by adding an impurity remover to the vanadium extraction tail liquid for precipitation after vanadium extraction from the vanadium slag, and the impurity remover is at least one of a calcium-based impurity remover, an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover.

7. The method for treating arsenic-containing tailings according to claim 6, characterized in that: The impurity remover is at least one of calcium sulfate, calcium oxalate, iron sulfate, aluminum sulfate, magnesium sulfate, and magnesium bicarbonate.

8. The method for treating arsenic-containing tailings according to claim 6, characterized in that: The impurity remover is at least one of an iron-based impurity remover, an aluminum-based impurity remover, and a magnesium-based impurity remover. During the dissolution treatment, quicklime is additionally added to the slurry.

9. The method for treating arsenic-containing tailings according to claim 8, characterized in that: The total molar amount of quicklime added additionally is more than twice the total molar amount of arsenic and fluorine in the arsenic-containing tailings.

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