Method for leaching bauxite ore pulp

Abstract

Disclosed in the present invention is a method for leaching bauxite ore pulp. The method comprises: obtaining bauxite raw ore pulp; pre-desilicating the bauxite raw ore pulp to obtain pre-desilicated ore pulp; preheating the pre-desilicated ore pulp to obtain dephosphorized ore pulp; and leaching the dephosphorized ore pulp to obtain leached bauxite ore pulp.

Description

A method for dissolving bauxite slurry

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311151987.2 filed on September 7, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of alumina production, and in particular to a method for dissolving bauxite slurry. Background Art

[0004] The alumina production process, including slurry preparation, dissolution, sedimentation, decomposition, and evaporation, is plagued by scabs throughout the process. Scabs during the dissolution process are particularly severe. Phosphorus scabs, primarily composed of calcium hydroxyphosphate, form during the high-temperature dissolution process. These scabs adhere stably and firmly to the inner walls of production pipes and storage tanks, significantly impacting the alumina production process.

[0005] Alumina manufacturers often mitigate scaling by adding pre-desiliconization processes and adding scale inhibitors. However, these efforts are less effective against phosphorus scaling (hydroxyapatite), which is hard and difficult to clean, significantly impacting the operating cycle. Scale inhibitors for scaling are generally organic, and their addition can increase the risk of organic matter or impurities in the system. Currently, acid leaching and high-pressure water washing are commonly used to clean scaling, which is costly.

[0006] Summary of the Invention

[0007] By utilizing one or more embodiments of the present disclosure, the technical problem of phosphorus scarring in pipelines being easily generated during the dissolution process of bauxite slurry is solved.

[0008] According to some embodiments of the present disclosure, a method for dissolving bauxite slurry is provided, the method comprising: obtaining bauxite raw slurry; pre-desiliconizing the bauxite raw slurry to obtain pre-desiliconizing slurry; preheating the pre-desiliconizing slurry to obtain dephosphorized slurry; and dissolving the dephosphorized slurry to obtain bauxite dissolved slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0011] FIG1 shows a schematic flow diagram of a method for dissolving bauxite slurry according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0013] Various embodiments of the present disclosure may be presented 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 the present disclosure; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range 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, 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.

[0014] In the present disclosure, unless otherwise specified, the directional words used, such as "upper" and "lower", specifically refer to the directions of the drawings in the accompanying drawings. In addition, in the description of the present disclosure, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely 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 three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to 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 plural 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, c can be single or multiple.

[0015] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present disclosure can be purchased from the market or prepared by relevant methods.

[0016] According to some embodiments of the present disclosure, a method for dissolving bauxite slurry, as shown in FIG1 , comprises:

[0017] Step S1, obtaining bauxite slurry;

[0018] Step S2, pre-desiliconizing the bauxite slurry to obtain a pre-desiliconized slurry;

[0019] Step S3, preheating the pre-desiliconization slurry to obtain dephosphorized slurry; and

[0020] Step S4: dissolving the dephosphorized slurry to obtain bauxite dissolution slurry.

[0021] In some embodiments, step S1 of obtaining bauxite ore slurry comprises: grinding bauxite, lime, circulating mother liquor and red mud to obtain bauxite ore slurry.

[0022] Among the raw materials of the above-mentioned bauxite slurry, bauxite is the core raw material for producing alumina; the role of lime: for diaspore-type bauxite, lime can not only eliminate the influence of titanium minerals and promote the dissolution of alumina, but also enable phosphate minerals to generate hydroxy calcium phosphate to reduce the phosphorus content in the system; for gibbsite ore, the addition of lime is mainly used to enable phosphate minerals to generate hydroxy calcium phosphate to reduce the phosphorus content in the system; the role of the circulating mother liquor: to dissolve the alumina in the bauxite, and the chemical composition of the circulating mother liquor can be NaOH, NaAl(OH)3, etc.; the role of red mud: as a crystal seed, to promote the formation of hydroxy calcium phosphate.

[0023] In some embodiments, the added weight of red mud is 1% to 10% of the added weight of bauxite.

[0024] In some embodiments of the present disclosure, the weight of the red mud added is controlled to be 1% to 10% of the weight of the bauxite added. The red mud can serve as a seed crystal to promote the formation of calcium hydroxyphosphate. If the amount of red mud added is too much, it will increase the solid content of the slurry to a certain extent, increasing the burden of red mud sedimentation. If the amount of red mud added is too little, the beneficial effect of the red mud on promoting the formation of calcium hydroxyphosphate will be reduced to a certain extent. In some embodiments, the weight of the red mud added can be 1%, 2%, 4%, 6%, 8%, 10%, etc., of the weight of the bauxite added.

[0025] In some embodiments, the added weight of lime is 3% to 12% of the added weight of bauxite.

[0026] The weight of the added lime is controlled to be 3% to 12% of the weight of the bauxite. For diaspore-type bauxite, lime can not only eliminate the effects of titanium minerals and promote the dissolution of alumina, but also convert phosphate minerals into calcium hydroxyphosphate, reducing the phosphorus content in the system. For gibbsite ore, the addition of lime is primarily used to convert phosphate minerals into calcium hydroxyphosphate, reducing the phosphorus content in the system. If the amount of lime added is too much, it will cause a certain degree of alumina loss; if the amount of lime added is too little, it will weaken the beneficial effects of eliminating the effects of titanium minerals, promoting the dissolution of alumina, and converting phosphate minerals into calcium hydroxyphosphate. In some embodiments, the weight of the added lime can be 3%, 5%, 7%, 9%, 11%, 12%, etc., of the weight of the bauxite.

[0027] In some embodiments, in step S2, the bauxite ore slurry is pre-desiliconized to obtain the pre-desiliconized slurry. The process parameters of the pre-desiliconization may include: the pre-desiliconization temperature, the pre-desiliconization time and the pre-desiliconization solid content; wherein the pre-desiliconization temperature is 90°C to 105°C, the pre-desiliconization time is 6h to 15h, and the pre-desiliconization solid content is 300g / L to 1000g / L.

[0028] In some embodiments of the present disclosure, a pre-desiliconization process can be implemented to mitigate the formation of silicon scabs (sodium silicate slag, cancrystal, hydrated garnet, etc.) and titanium scabs (perovskite, hydroxy perovskite). The pre-desiliconization temperature is controlled to promote the reaction of silicon minerals in the bauxite to form sodium silicate slag, thereby increasing desiliconization efficiency and mitigating the formation of silicon scabs.

[0029] In some embodiments, the pre-desiliconization temperature may be 90° C., 95° C., 100° C., 105° C., etc. Controlling the pre-desiliconization time to 6 to 15 hours can promote the reaction of silicon minerals in the bauxite to form sodium silicate slag, thereby increasing the desiliconization efficiency and slowing down the formation of silicon scars.

[0030] In some embodiments, the pre-desiliconization time can be 6h, 9h, 12h, 15h, etc. If the pre-desiliconization temperature is too high or the pre-desiliconization time is too long, energy consumption will be increased to a certain extent; if the pre-desiliconization temperature is too low or the pre-desiliconization time is too short, the silicon mineral reaction will be insufficient and the desiliconization efficiency will be low to a certain extent. The pre-desiliconization solid content is controlled to be 300g / L to 1000g / L. The pre-desiliconization solid content can increase the SiO2 concentration in the slurry and generate more sodium silicate slag in the reaction. The sodium silicate slag acts as a seed crystal to further promote the desiliconization of the solution and has a positive effect on slowing down scarring. If the pre-desiliconization solid content is too high, the viscosity of the pre-desiliconization slurry will be increased to a certain extent, resulting in poor fluidity of the pre-desiliconization slurry and difficulty in transportation. If the pre-desiliconization solid content is too low, the desiliconization effect will be poor to a certain extent, and the molecular weight of the subsequent dissolution solution will be relatively high, resulting in low production efficiency. In some embodiments, the pre-desiliconization solid content can be 300 g / L, 400 g / L, 500 g / L, 600 g / L, 700 g / L, 800 g / L, 900 g / L, 1000 g / L, etc.

[0031] In some embodiments, in step S3, preheating the pre-desiliconized slurry to obtain the dephosphorized slurry, the preheating process parameters include: preheating temperature and preheating time.

[0032] In some embodiments, the preheating temperature may be 220°C to 260°C.

[0033] In some embodiments, the preheating temperature may be 240°C to 260°C.

[0034] Setting up a preheating process is equivalent to setting up a dephosphorization process, which can slow down the formation of phosphorus scars during the dissolution process. While slowing down the formation of silicon and titanium scars, it can also slow down the formation of phosphorus scars, effectively extending the operating cycle and reducing the number of scar cleaning times.

[0035] In some embodiments of the present disclosure, the above-mentioned preheating temperature is controlled to be 220℃~260℃. The reaction rate of the phosphate minerals in the ore is higher within this temperature range, which is more conducive to the generation of hydroxy calcium phosphate by the phosphate minerals and the entry into the red mud, resulting in better dephosphorization effect. Generally, the high-temperature dissolution temperature of bauxite is 260~280℃, and the preheating temperature does not need to be higher than the dissolution temperature. When the preheating temperature is too high, the requirements for equipment and pipelines will be higher, and thus the investment cost will be higher; if the preheating temperature is too low, it will lead to a low reaction rate of the phosphate minerals and insufficient dephosphorization to a certain extent. In some embodiments, the preheating temperature can be 220℃, 230℃, 240℃, 250℃, 260℃, etc. In other embodiments, the preheating temperature can be 240℃~260℃.

[0036] In some embodiments, the preheating time is greater than 30 minutes.

[0037] Controlling the above-mentioned preheating time to be greater than 30 minutes is conducive to more complete reaction of the phosphorus minerals, thereby achieving better dephosphorization effect. If the time is too short, the dephosphorization effect will be poor to a certain extent. In some embodiments, the preheating time can be 40 minutes, 50 minutes, 60 minutes, 70 minutes, etc.

[0038] In some embodiments, in step S4 of dissolving the dephosphorized slurry to obtain bauxite dissolution slurry, the dissolution temperature is 260°C to 280°C.

[0039] Controlling the dissolution temperature between 260°C and 280°C can achieve good alumina dissolution and a high dissolution rate. If the dissolution temperature is too high, it will place higher demands on equipment and pipelines, significantly increasing investment costs. If the dissolution temperature is too low, the alumina dissolution rate will be reduced to a certain extent. In some embodiments, the dissolution temperature can be 260°C, 265°C, 270°C, 275°C, 280°C, etc. Alumina production can continue after step S4.

[0040] The technical solutions of the present disclosure are further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present disclosure and are not intended to limit the scope of the present disclosure. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national standards. If there are no corresponding national standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0041] According to some embodiments of the present disclosure, a method for dissolving bauxite slurry comprises:

[0042] S1, obtaining bauxite slurry;

[0043] S2. Pre-desiliconizing the bauxite slurry to obtain a pre-desiliconized slurry;

[0044] S3, preheating the pre-desiliconization slurry to obtain a dephosphorized slurry; and

[0045] S4, dissolving the dephosphorized slurry to obtain bauxite dissolution slurry. The process parameters of this method are shown in the following Examples 1-8 and Comparative Examples 1-2.

[0046] Comparative Example 1

[0047] Bauxite #1, containing 0.15% P2O5, is used in alumina production. First, the bauxite, lime, and recycled mother liquor are ball-milled in a specific ratio to prepare a bauxite slurry. The lime is added to the slurry in an amount of 5% by weight of the bauxite. The slurry is then pre-desiliconized at a pre-desiliconization temperature of 90°C, a pre-desiliconization time of 8 hours, and a pre-desiliconization solids content of 400 g / L to obtain a pre-desiliconized slurry. The pre-desiliconized slurry is then preheated to 265°C to obtain a dephosphorized slurry. The dephosphorized slurry is then subjected to a 60-minute dissolution treatment to obtain a bauxite dissolution slurry.

[0048] Comparative Example 2

[0049] Bauxite 2# contains 0.25% P2O5. This bauxite is used in alumina production. First, the bauxite, lime, and recycled mother liquor are ball-milled in a specific ratio to prepare a bauxite slurry. The lime is added to the slurry at a rate of 9% by weight of the bauxite. The slurry is then pre-desiliconized at a temperature of 90°C, a time of 8 hours, and a solid content of 400 g / L. This pre-desiliconized slurry is then preheated to 265°C to produce a dephosphorized slurry. The dephosphorized slurry is then subjected to a 60-minute dissolution treatment to obtain a bauxite dissolution slurry.

[0050] Example 1

[0051] This technical solution is used for 1# bauxite. Bauxite, lime, recycled mother liquor, and a small amount of red mud are ball-milled in specific proportions to prepare a raw bauxite slurry. The lime and red mud are added in an amount of 5% by weight of the bauxite, and 2% by weight of the bauxite. The raw bauxite slurry is pre-desiliconized at a pre-desiliconization temperature of 95°C, a pre-desiliconization time of 8 hours, and a pre-desiliconization solids content of 400g / L to obtain a pre-desiliconized slurry. The pre-desiliconized slurry is preheated to 230°C and then held in an autoclave for 60 minutes to obtain a dephosphorized slurry. The dephosphorized slurry is then heated to 265°C and subjected to a dissolution treatment for 60 minutes to obtain a bauxite dissolution slurry.

[0052] Example 2

[0053] This technical solution is used for 1# bauxite. Bauxite, lime, recycled mother liquor, and a small amount of red mud are ball-milled in a specific ratio to prepare a raw bauxite slurry. The amount of lime added to the raw bauxite slurry is 5% by weight of the bauxite, and the amount of red mud added is 5% by weight of the bauxite. The raw bauxite slurry is pre-desiliconized at a pre-desiliconization temperature of 105°C, a pre-desiliconization time of 10 hours, and a pre-desiliconization solid content of 600g / L to obtain a pre-desiliconized slurry. The pre-desiliconized slurry is preheated to 240°C and then held in an autoclave for 60 minutes to obtain a dephosphorized slurry. The dephosphorized slurry is then heated to 265°C and subjected to a dissolution treatment for 60 minutes to obtain a bauxite dissolution slurry.

[0054] Example 3

[0055] This technical solution is used for 1# bauxite. Bauxite, lime, recycled mother liquor, and a small amount of red mud are ball-milled in specific proportions to prepare a raw bauxite slurry. The lime and red mud are added in an amount of 5% by weight of the bauxite, and 8% by weight of the bauxite. The raw bauxite slurry is pre-desiliconized at a pre-desiliconization temperature of 105°C, a pre-desiliconization time of 10 hours, and a pre-desiliconization solids content of 600g / L to obtain a pre-desiliconized slurry. The pre-desiliconized slurry is preheated to 250°C and then held in an autoclave for 60 minutes to obtain a dephosphorized slurry. The dephosphorized slurry is then heated to 270°C and subjected to a dissolution treatment for 60 minutes to obtain a bauxite dissolution slurry.

[0056] Example 4

[0057] This technical solution is used for 1# bauxite. Bauxite, lime, recycled mother liquor, and a small amount of red mud are ball-milled in a certain proportion to prepare a raw bauxite slurry. The amount of lime added to the raw bauxite slurry is 5% by weight of the bauxite, and the amount of red mud added is 10% by weight of the bauxite. The raw bauxite slurry is pre-desiliconized at a pre-desiliconization temperature of 105°C, a pre-desiliconization time of 10 hours, and a pre-desiliconization solid content of 600g / L to obtain a pre-desiliconized slurry. The pre-desiliconized slurry is preheated to 260°C and then held in an autoclave for 40 minutes to obtain a dephosphorized slurry. The dephosphorized slurry is then heated to 270°C and subjected to a dissolution treatment for 60 minutes to obtain a bauxite dissolution slurry.

[0058] Example 5

[0059] This technical solution is used for bauxite No. 2. Bauxite, lime, recycled mother liquor, and a small amount of red mud are ball-milled in specific proportions to prepare a raw bauxite slurry. The lime and red mud are added in an amount of 8% by weight of the bauxite, and 2% by weight of the bauxite. The raw bauxite slurry is pre-desiliconized at a pre-desiliconization temperature of 95°C, a pre-desiliconization time of 8 hours, and a pre-desiliconization solids content of 400g / L to obtain a pre-desiliconized slurry. The pre-desiliconized slurry is preheated to 230°C and then held in an autoclave for 60 minutes to obtain a dephosphorized slurry. The dephosphorized slurry is then heated to 265°C and subjected to a dissolution treatment for 60 minutes to obtain a bauxite dissolution slurry.

[0060] Example 6

[0061] This technical solution was used for bauxite No. 2. Bauxite, lime, recycled mother liquor, and a small amount of red mud were ball-milled in specific proportions to produce a raw bauxite slurry. The lime content was 8% by weight of the bauxite, and the red mud content was 5%. The raw bauxite slurry was pre-desiliconized at a temperature of 105°C, a time of 10 hours, and a solids content of 600 g / L. The pre-desiliconized slurry was preheated to 240°C and then held in an autoclave for 60 minutes to produce a dephosphorized slurry. The dephosphorized slurry was then heated to 265°C and subjected to a 60-minute dissolution treatment to produce a bauxite dissolution slurry.

[0062] Example 7

[0063] This technical solution was used for bauxite No. 2. Bauxite, lime, recycled mother liquor, and a small amount of red mud were ball-milled in specific proportions to produce a raw bauxite slurry. The lime and red mud were added in amounts of 8% and 8% of the bauxite weight, respectively. The raw bauxite slurry was pre-desiliconized at a temperature of 105°C, a time of 10 hours, and a solids content of 600 g / L. The pre-desiliconized slurry was preheated to 250°C and then held in an autoclave for 60 minutes to produce a dephosphorized slurry. The dephosphorized slurry was then heated to 270°C and subjected to a 60-minute dissolution treatment to produce a bauxite dissolution slurry.

[0064] Example 8

[0065] This technical solution was used for the 2# bauxite ore. Bauxite, lime, recycled mother liquor, and a small amount of red mud were ball-milled in specific proportions to produce a raw bauxite slurry. The lime content was 8% by weight of the bauxite, and the red mud content was 10% by weight. The raw bauxite slurry was pre-desiliconized at a pre-desiliconization temperature of 105°C, a pre-desiliconization time of 10 hours, and a pre-desiliconization solids content of 600 g / L to produce a pre-desiliconized slurry. The pre-desiliconized slurry was preheated to 260°C and then held in an autoclave for 40 minutes to produce a dephosphorized slurry. The dephosphorized slurry was then heated to 270°C and subjected to a dissolution treatment for 60 minutes to produce a bauxite dissolution slurry.

[0066] According to the method of dissolving bauxite slurry in the above-mentioned Examples 1-8 and Comparative Examples 1-2, the operation cycle of the dissolution pipeline can be seen in Table 1.

[0067] Table 1 Operation cycle of dissolution pipeline

[0068] The method for dissolving bauxite slurry according to the disclosed embodiments effectively slows the formation of phosphorus scabs in the dissolution pipeline, while also slowing the formation of silicon and titanium scabs. This significantly extends the operating cycle (as shown in Table 1) and reduces the number of scab cleanings. Furthermore, this technology offers the advantages of low investment, low cost, and ease of industrial application.

[0069] The method for dissolving bauxite slurry according to some embodiments of the present disclosure has the following advantages compared with related technologies:

[0070] According to some embodiments of the present disclosure, a method for dissolving bauxite slurry includes a preheating and dephosphorization step after obtaining the raw bauxite slurry and pre-desiliconizing the slurry, but before dissolving the slurry. This facilitates the reaction of phosphate minerals in the bauxite to form calcium hydroxyphosphate, which enters the red mud, reducing the phosphorus content in the solution and slowing down the formation of scabs in the dissolution pipeline. Compared with related technologies, this method can effectively slow the formation of phosphorus scabs in the dissolution pipeline, while also slowing the formation of silicon and titanium scabs, significantly extending the operating cycle and reducing the number of scab cleanings. This method also has the advantages of low investment, low cost, and ease of industrial application.

[0071] The foregoing description is intended only to provide specific embodiments of the present disclosure, which will enable those skilled in the art to understand and implement the present disclosure. 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 the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments shown herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for dissolving bauxite slurry, comprising: Obtaining bauxite ore slurry; Pre-desiliconizing the raw bauxite slurry to obtain pre-desiliconized slurry; Preheating the pre-desiliconization slurry to obtain a dephosphorized slurry; as well as, The dephosphorized slurry is dissolved to obtain bauxite dissolved slurry.

2. The method according to claim 1, wherein: The preheating process parameters include: preheating temperature and preheating time.

3. The method according to claim 2, wherein: The preheating temperature is 220°C to 260°C.

4. The method according to claim 3, wherein: The preheating temperature is 240°C to 260°C.

5. The method according to any one of claims 2 to 4, wherein: The preheating time is greater than 30 minutes.

6. The method according to claim 1, wherein: The method of obtaining the bauxite ore slurry comprises: Bauxite, lime, circulating mother liquor and red mud are ground to obtain bauxite slurry.

7. The method according to claim 6, wherein: The added weight of the red mud is 1% to 10% of the added weight of the bauxite.

8. The method according to claim 6 or 7, wherein: The added weight of the lime is 3% to 12% of the added weight of the bauxite.

9. The method according to claim 1, wherein: The process parameters of the pre-desiliconization include: the pre-desiliconization temperature, the pre-desiliconization time and the pre-desiliconization solid content; wherein, The pre-desiliconization temperature is 90° C. to 105° C., the pre-desiliconization time is 6 h to 15 h, and the pre-desiliconization solid content is 300 g / L to 1000 g / L.

10. The method according to claim 1, wherein: The dissolution temperature is 260°C to 280°C.

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