A method for leaching bauxite

Abstract

This application relates to a leaching method for bauxite, the method comprising the following steps: providing bauxite; mixing the bauxite with a mother liquor and grinding it to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 190–195 g / L; treating the slurry through a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 1.5%–2% of the total solid mass of the overflow, and particles larger than 100 mesh account for 30%–32% of the total solid mass of the overflow; subjecting the overflow to leaching treatment to obtain a leaching slurry; evaporating and concentrating the leaching slurry to obtain a concentrated slurry, and controlling the α-coefficient of the concentrated slurry. k The concentration is 1.3 to 1.35; the concentrate is diluted and settled to obtain crude sodium aluminate solution. This application can effectively reduce the occurrence of silo phenomenon and improve the A / S ratio of the concentrated slurry.

Description

Technical Field

[0001] This application relates to the aluminum industry, and in particular to bauxite. Background Technology

[0002] Bauxite is the main raw material for alumina production. my country is the world's largest alumina producer, but its alumina production capacity and bauxite reserves are extremely disproportionate, accounting for less than 3% of global bauxite reserves. Currently, the distribution of China's alumina industry clusters is shifting from resource-rich provinces to coastal areas. With increasingly stringent environmental inspections and mine management, the supply and demand imbalance of bauxite resources is becoming more pronounced. Inland regions such as Henan, Shanxi, and Chongqing are forced to turn to imported ore, leading to a year-on-year increase in my country's dependence on overseas bauxite. Given the significant advantages of imported ore, imports are expected to continue to grow for a considerable period. While imported ore fills the supply and demand gap in the domestic market, its significant differences in properties compared to domestically produced ore present new technological challenges and require new strategies.

[0003] The main component of bauxite is alumina hydrate, in addition to which it contains impurities such as silicon, iron, titanium, and organic matter. The alumina and silica content in the ore are the main evaluation indicators, while impurity elements such as titanium, sulfur, and carbon are also important indicators. These impurities all pose varying degrees of harm to production, with organic matter being particularly prominent in imported ores. During the leaching process, carbon in the ore is converted into liquid-phase organic carbon, which, after multiple cycles, is eventually degraded into low-molecular-weight organic compounds such as oxalates. This leads to a series of hazards, such as scaling in the decomposition tank, decreased decomposition rate, finer particle size, and increased suspended solids, ultimately resulting in easy storage and a low leaching A / S ratio. While domestic and international scholars have conducted extensive research on the hazards, prevention, and removal of organic matter, research on the leaching and transformation of organic carbon is relatively limited. Summary of the Invention

[0004] This application provides a bauxite leaching method to solve the technical problems of easy scavenging and low A / S ratio in the leaching process of bauxite with high organic content.

[0005] This application provides a method for leaching bauxite, the method comprising the following steps:

[0006] A bauxite is provided, which is then mixed with a mother liquor and ground to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 190-195 g / L.

[0007] The slurry is processed by a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 1.5% to 2% of the total solid mass, and particles larger than 100 mesh account for 30% to 32% of the total solid mass.

[0008] The overflow is subjected to a leaching treatment to obtain a leaching slurry;

[0009] The dissolved slurry is evaporated and concentrated to obtain a concentrated slurry. The α value of the concentrated slurry is controlled. k It ranges from 1.3 to 1.35;

[0010] The concentrate was diluted and allowed to settle to obtain crude sodium aluminate solution.

[0011] In some embodiments of this application, the bauxite is mixed with mother liquor, and the ratio of mother liquor to bauxite is 3.97 to 4.4:1.

[0012] In some embodiments of this application, the temperature of the leaching treatment is 137–140°C.

[0013] In some embodiments of this application, the A / S ratio of the leaching slurry is 148 to 152.

[0014] In some embodiments of this application, the solid content of the concentrate is 88-92 g / L.

[0015] In some embodiments of this application, the α of the crude sodium aluminate solution k Not greater than α of the concentrated slurry k +0.04.

[0016] In some embodiments of this application, the concentration is diluted and settled at a settling temperature of 90–95°C.

[0017] In some embodiments of this application, the method further includes the following steps:

[0018] The crude sodium aluminate solution was prepared into refined sodium aluminate solution.

[0019] In some embodiments of this application, the AO of the sodium aluminate semen is 170-173 g / L.

[0020] In some embodiments of this application, the A / S ratio of the sodium aluminate semen is 178 to 182.

[0021] The technical solutions provided in this application have the following advantages compared with the prior art:

[0022] The bauxite leaching method provided in this application involves adjusting the caustic alkali concentration of the mother liquor, screening the slurry with particles of a specific mesh size using a hydrocyclone, and controlling the α-coal content of the concentrated slurry. k It can effectively reduce the occurrence of silo phenomena and improve the A / S ratio of concentrated slurry. Attached Figure Description

[0023] 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.

[0024] 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.

[0025] Figure 1 This is a schematic flowchart of a bauxite leaching method provided in an embodiment of this application. Detailed Implementation

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Existing bauxite leaching processes with high organic content suffer from technical problems such as easy scavenging and low leaching A / S ratio.

[0030] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0031] This application provides a method for leaching bauxite, the method comprising the following steps:

[0032] S1: Provide bauxite, mix the bauxite with mother liquor and grind it to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 190-195 g / L;

[0033] S2: The slurry is processed by a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 1.5% to 2% of the total mass of solids, and particles larger than 100 mesh account for 30% to 32% of the total mass of solids.

[0034] S3: The overflow is subjected to a dissolution treatment to obtain a dissolution slurry;

[0035] S4: Evaporate and concentrate the dissolved slurry to obtain a concentrated slurry, and control the α of the concentrated slurry. k It ranges from 1.3 to 1.35;

[0036] S5: The concentrated solution is diluted and settled to obtain crude sodium aluminate solution.

[0037] Those skilled in the art will understand that the term "mother liquor" is a conventional technical term in the field, referring to the sodium aluminate solution remaining after the subsequent sodium aluminate decomposition process.

[0038] Those skilled in the art will understand that the caustic alkali concentration in the Bayer process for alumina production refers to the concentration of Na2O, which is either compounded as sodium aluminate or exists in the form of sodium hydroxide.

[0039] Those skilled in the art will understand that the leaching treatment of the overflow refers to treating the overflow containing bauxite particles with a strong alkali to dissolve the alumina in the bauxite and generate sodium aluminate.

[0040] Those skilled in the art will understand that dilution and sedimentation are conventional treatment methods for bauxite leachates, used to separate sodium aluminate solutions from slurry.

[0041] This application achieves this by adjusting the caustic alkali concentration of the mother liquor, screening the slurry with particles of a specific mesh size using a hydrocyclone, and controlling the α-coal content of the concentrated slurry. k A specific mesh size for the slurry facilitates slurry flow and uniform feeding, preventing accumulation and blockage at the feeding point, thus avoiding slugging. Controlling the caustic alkali concentration in the concentrated slurry (αk) and mother liquor allows for more complete ore dissolution, promoting the full dissolution of AO content in the ore, while reducing SiO2 precipitation and lowering the Si content in the solution. In summary, this application can effectively reduce slugging and improve the A / S ratio of the concentrated slurry.

[0042] Those skilled in the art will understand that A / S refers to the silicon content index.

[0043] In some embodiments of this application, the bauxite is mixed with mother liquor, and the ratio of mother liquor to bauxite is 3.97 to 4.4:1.

[0044] The beneficial effect of having a mother liquor to bauxite ratio of 3.97 to 4.4:1 is that it helps the ore to dissolve fully and increases the dissolution rate.

[0045] In some embodiments of this application, the temperature of the leaching treatment is 137–140°C.

[0046] The beneficial effect of using a leaching treatment temperature of 137–140°C is to ensure that AO in the ore is fully dissolved, while suppressing the precipitation of SiO2.

[0047] In some embodiments of this application, the A / S ratio of the leaching slurry is 148 to 152.

[0048] The beneficial effect of the leaching slurry having an A / S ratio of 148-152 is that less SiO2 is precipitated from the ore, which helps to reduce Si scaling in downstream processes and also provides quality assurance for the hydrogen aluminum products from the decomposition process.

[0049] In some embodiments of this application, the solid content of the concentrate is 88-92 g / L.

[0050] The beneficial effect of having a solid content of 88-92 g / L in the concentrate is that it helps the ore to dissolve fully, providing a basic condition for maintaining a clear liquid in the settling process.

[0051] In some embodiments of this application, the α of the crude sodium aluminate solution k Not greater than α of the concentrated slurry k +0.04.

[0052] The α of the crude sodium aluminate solution k The beneficial effect of controlling the process within the above range is to provide sufficient decomposition power for downstream processes while ensuring semen A / S ratio.

[0053] In some embodiments of this application, the concentration is diluted and settled at a settling temperature of 90–95°C.

[0054] In some embodiments of this application, the method further includes the following steps:

[0055] S6: Prepare sodium aluminate concentrate from the crude sodium aluminate solution.

[0056] Those skilled in the art can prepare sodium aluminate concentrate from crude sodium aluminate solution using conventional methods. In some embodiments, a leaf filter is used to prepare the sodium aluminate concentrate from the crude sodium aluminate solution. When processing bauxite with high organic content using existing methods, the settling process is often ineffective, leading to poor material flow through the leaf filter, resulting in reduced production and impacting output. The method of this application effectively separates most of the insoluble matter during the settling process, facilitating subsequent processes. In practice, the supernatant layer formed by the settling process of this application can reach a height of over 8 meters.

[0057] In some embodiments of this application, the AO of the sodium aluminate semen is 170-173 g / L.

[0058] The beneficial effect of the sodium aluminate semen having an AO of 170-173 g / L is that it helps to control the semen A / S ratio to 178-182.

[0059] In some embodiments of this application, the A / S ratio of the sodium aluminate semen is 178 to 182.

[0060] 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 national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0061] Example 1

[0062] This embodiment provides a method for leaching bauxite, the method comprising the following steps:

[0063] Sa: Provide bauxite, mix the bauxite with mother liquor and grind it to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 190 g / L;

[0064] Sb: The slurry is processed by a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 1.5% of the total mass of solids and particles larger than 100 mesh account for 30% of the total mass of solids.

[0065] Sc: The overflow is subjected to leaching treatment to obtain a leaching slurry;

[0066] Sd: The dissolved slurry is evaporated and concentrated to obtain a concentrated slurry, and the α of the concentrated slurry is controlled. k It is 1.3;

[0067] Se: The concentrate is diluted and precipitated to obtain crude sodium aluminate solution;

[0068] Sf: Prepare sodium aluminate concentrate from the crude sodium aluminate solution.

[0069] The bauxite is mixed with mother liquor, wherein the ratio of mother liquor to bauxite is 4:1.

[0070] The leaching treatment temperature is 137°C.

[0071] The A / S ratio of the leaching slurry is 148.

[0072] The solid content of the concentrate is 88 g / L.

[0073] The sedimentation is carried out in a sedimentation tank 12m deep, and the supernatant layer in the sedimentation tank is 8m high.

[0074] The α of the crude sodium aluminate solution k α is the concentrated slurry k +0.04, which is 1.34.

[0075] The AO of the sodium aluminate semen was 170 g / L.

[0076] The concentrate is diluted and settled at a settling temperature of 90°C.

[0077] The A / S ratio of the sodium aluminate semen was 178.

[0078] Example 2

[0079] This embodiment provides a method for leaching bauxite, the method comprising the following steps:

[0080] Sa: Provide bauxite, mix the bauxite with mother liquor and grind it to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 195 g / L;

[0081] Sb: The slurry is processed by a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 2% of the total mass of solids and particles larger than 100 mesh account for 32% of the total mass of solids.

[0082] Sc: The overflow is subjected to leaching treatment to obtain a leaching slurry;

[0083] Sd: The dissolved slurry is evaporated and concentrated to obtain a concentrated slurry, and the α of the concentrated slurry is controlled. k It is 1.35;

[0084] Se: The concentrate is diluted and precipitated to obtain crude sodium aluminate solution;

[0085] Sf: Prepare sodium aluminate concentrate from the crude sodium aluminate solution.

[0086] The bauxite is mixed with mother liquor, and the ratio of mother liquor to bauxite is 4.3:1.

[0087] The leaching treatment temperature is 140°C.

[0088] The A / S ratio of the leaching slurry is 152.

[0089] The solid content of the concentrate is 92 g / L.

[0090] The sedimentation is carried out in a sedimentation tank that is 12m deep, and the supernatant layer in the sedimentation tank is 10m high.

[0091] The α of the crude sodium aluminate solution k α is the concentrated slurry k +0.03, which is 1.38.

[0092] The AO of the sodium aluminate semen was 173 g / L.

[0093] The concentrate is diluted and settled at a settling temperature of 95°C.

[0094] The A / S ratio of the sodium aluminate semen was 182.

[0095] Example 3

[0096] This embodiment provides a method for leaching bauxite, the method comprising the following steps:

[0097] Sa: Provide bauxite, mix the bauxite with mother liquor and grind it to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 192 g / L;

[0098] Sb: The slurry is processed by a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 1.7% of the total solid mass and particles larger than 100 mesh account for 31% of the total solid mass.

[0099] Sc: The overflow is subjected to leaching treatment to obtain a leaching slurry;

[0100] Sd: The dissolved slurry is evaporated and concentrated to obtain a concentrated slurry, and the α of the concentrated slurry is controlled. k It is 1.32;

[0101] Se: The concentrate is diluted and precipitated to obtain crude sodium aluminate solution;

[0102] Sf: Prepare sodium aluminate concentrate from the crude sodium aluminate solution.

[0103] The bauxite is mixed with mother liquor, wherein the ratio of mother liquor to bauxite is 3.97:1.

[0104] The leaching treatment temperature is 139°C.

[0105] The A / S ratio of the leaching slurry is 149.

[0106] The solid content of the concentrate is 89 g / L.

[0107] The sedimentation is carried out in a sedimentation tank 12m deep, and the supernatant layer in the sedimentation tank is 9.3m high.

[0108] The α of the crude sodium aluminate solution k α is the concentrated slurry k +0.04, which is 1.36.

[0109] The AO of the sodium aluminate semen was 171 g / L.

[0110] The concentrate is diluted and settled at a settling temperature of 91°C.

[0111] The A / S ratio of the sodium aluminate semen is 180.

[0112] Example 4

[0113] This embodiment provides a method for leaching bauxite, the method comprising the following steps:

[0114] Sa: Provide bauxite, mix the bauxite with mother liquor and grind it to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 194 g / L;

[0115] Sb: The slurry is processed by a hydrocyclone to obtain an overflow, wherein particles larger than 20 mesh account for 1.9% of the total mass of solids and particles larger than 100 mesh account for 30% of the total mass of solids.

[0116] Sc: The overflow is subjected to leaching treatment to obtain a leaching slurry;

[0117] Sd: The dissolved slurry is evaporated and concentrated to obtain a concentrated slurry, and the α of the concentrated slurry is controlled. k It is 1.34;

[0118] Se: The concentrate is diluted and precipitated to obtain crude sodium aluminate solution;

[0119] Sf: Prepare sodium aluminate concentrate from the crude sodium aluminate solution.

[0120] The bauxite is mixed with mother liquor, wherein the ratio of mother liquor to bauxite is 4.4:1.

[0121] The leaching treatment temperature is 138°C.

[0122] The A / S ratio of the leaching slurry is 151.

[0123] The solid content of the concentrate is 91 g / L.

[0124] The sedimentation is carried out in a sedimentation tank 12m deep, and the supernatant layer in the sedimentation tank is 8.6m high.

[0125] The α of the crude sodium aluminate solution k α is the concentrated slurry k +0.01, which is 1.35.

[0126] The AO of the sodium aluminate semen was 173 g / L.

[0127] The concentrate is diluted and settled at a settling temperature of 94°C.

[0128] The A / S ratio of the sodium aluminate semen is 181.

[0129] No sumption occurred during the implementation of Examples 1 to 4. The A / S ratio of the leaching slurry and the A / S ratio of the sodium aluminate concentrate both reached a high level, and the supernatant layer height in the settling tank was not less than 8m.

[0130] 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.

[0131] 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.

[0132] 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 leaching bauxite, characterized in that, The method includes the following steps: A bauxite is provided, which is then mixed with a mother liquor and ground to obtain a slurry, wherein the caustic alkali concentration of the mother liquor is 190~195 g / L; The slurry is processed by a hydrocyclone to obtain an overflow, in which particles larger than 20 mesh account for 1.5% to 2% of the total solid mass, and particles larger than 100 mesh account for 30% to 32% of the total solid mass. The overflow is subjected to a leaching treatment to obtain a leaching slurry. The leaching treatment temperature is 137~140℃. The dissolved slurry is evaporated and concentrated to obtain a concentrated slurry. The α value of the concentrated slurry is controlled. k The concentration is 1.3~1.35, and the solid content of the concentrated slurry is 88~92 g / L; The concentrated slurry was diluted and settled to obtain crude sodium aluminate solution at a settling temperature of 90-95℃. The α-value of the crude sodium aluminate solution... k Not greater than α of the concentrated slurry k +0.

04.

2. The bauxite leaching method according to claim 1, characterized in that, The bauxite is mixed with mother liquor, wherein the ratio of mother liquor to bauxite is 3.97 to 4.4:

1.

3. The bauxite leaching method according to claim 1, characterized in that, The A / S ratio of the leaching slurry is 148~152.

4. The bauxite leaching method according to claim 1, characterized in that, The method further includes the following steps: The crude sodium aluminate solution was prepared into refined sodium aluminate solution.

5. The bauxite leaching method according to claim 4, characterized in that, The AO of the sodium aluminate semen was 170~173 g / L.

6. The bauxite leaching method according to claim 4, characterized in that, The A / S ratio of the sodium aluminate semen is 178~182.

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