Sorting method for aluminum electrolysis anode scrap fine particulate matter

Abstract

The invention provides a sorting method for aluminum electrolysis anode scrap fine particles, and belongs to the field of solid waste treatment. The method comprises the steps that the aluminum electrolysis anode scrap fine particulate matter is subjected to first-stage screening classification, and first-stage oversize products and first-stage undersize products are obtained; the first-section oversize product is subjected to first dense medium cyclone separation, and first gravity separation refined carbon and first gravity separation tailings are obtained; the first-section screen underflow is subjected to first spiral chute separation, and first refined carbon and first tailings are obtained; the first gravity separation tailings are subjected to second dense medium cyclone separation, and second gravity separation cryolite concentrate and second gravity separation tailings are obtained; the first tailings are subjected to second spiral chute separation, and second cryolite concentrate and second tailings are obtained; and the first gravity concentration refined carbon and the first refined carbon are combined to obtain refined carbon, and the second gravity concentration cryolite concentrate and the second cryolite concentrate are combined to obtain cryolite concentrate. According to the method, a reselection process more adaptive to the physical property of the anode scrap is introduced, and efficient separation of carbon-ash and cryolite-ash is achieved through the material density difference.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste treatment, and particularly relates to a sorting method of aluminum electrolysis residual anode fine particles. BACKGROUND

[0002] The aluminum electrolysis residual anode is the residual part after the prebaked anode electrolysis cycle ends in the electrolytic cell. Due to long-term contact with the electrolyte, it contains a high content of electrolyte components such as aluminum, sodium, fluorine, etc. After cleaning, it can generally be used as raw material into the carbon production line, which can improve the anode density and improve the physical properties of the anode to a certain extent, and it is also an important way for the carbon plant to reduce the production cost of the anode. A large amount of residual anode fine particles with small particle size are left over during the recovery of the residual anode. The high content of impurity elements brought by these poor quality residual anodes seriously affects the electrical conductivity and air and carbon dioxide reactivity of the anode, causing the carbon particles of the prebaked anode to fall off and cannot be directly returned to the carbon production. In the process of prebaked cell aluminum smelting, the anode consumption is 450-500 kg / t-Al, and about 80-120 kg / t-Al of residual anode is generated, of which the residual anode fine particles account for about 10%-20%. At present, the electrolytic aluminum production supporting the anode is about 200 million tons, so the residual anode fine particles account for about 200-400 million tons. If these residual anode fine particles that are difficult to recover and utilize are not treated, it will cause great waste of resources.

[0003] At present, the research on the disposal of residual anodes includes residual anode automatic cleaning system or device, residual anode electrolyte screening and cleaning system and device, residual anode crushing and recycling equipment and recycling method, etc. However, most of these systems or devices are suitable for residual anode blocks or particles with larger particle size (above 3 mm), and these residual anodes can be returned to the anode production after being treated by automatic technology or high-efficiency cleaning of surface electrolyte. However, the residual anode fine particles left after cleaning and screening are mixed with carbon particles due to the aggregation of many and complex impurities, and it is difficult to clean or sort by mechanical means. At present, there are few reports on the related process technology for efficient sorting of residual anode fine particles (below 3 mm). The impurity removal technology is generally divided into chemical method and physical method. The chemical method introduces acid and alkali reagents, which corrodes the equipment and still has complicated impurity elements in the waste liquid after disposal, and the waste salt produced finally is difficult to handle, which brings pressure to environmental protection. The physical method includes flotation, gravity separation, magnetic separation and other mineral processing technologies. For example, the flotation process is used to separate carbon and cryolite in aluminum electrolytic carbon slag, but this method has large reagent consumption and high cost, and the raw material needs to be crushed, and the operation control process requires strict control. The residual anode fine particles are waste slag, and the low cost and low disposal difficulty are the difficulties that need to be urgently developed. Therefore, adopting a high-efficiency sorting method of aluminum electrolysis residual anode fine particles has significant environmental, economic and social value in promoting resource comprehensive utilization, reducing enterprise cost and industry green upgrading. SUMMARY

[0004] The application provides a sorting method of aluminum electrolysis residual anode fine particles to provide an efficient sorting method of aluminum electrolysis residual anode fine particles.

[0005] The application provides a sorting method of aluminum electrolysis residual anode fine particles, and the method comprises the following steps: The aluminum electrolysis residual anode fine particles are subjected to first-stage screening classification to obtain first-stage screening oversize and first-stage screening undersize; The first-stage screening oversize is subjected to first-stage heavy medium cyclone sorting to obtain first-stage heavy sorting concentrate and first-stage heavy sorting tailings; The first-stage screening undersize is subjected to first-stage spiral chute sorting to obtain first-stage concentrate and first-stage tailings; The first-stage heavy sorting tailings are subjected to second-stage heavy medium cyclone sorting to obtain second-stage heavy sorting cryolite concentrate and second-stage heavy sorting tailings; The first-stage tailings are subjected to second-stage spiral chute sorting to obtain second-stage cryolite concentrate and second-stage tailings; and The first-stage heavy sorting concentrate and the first-stage concentrate are combined to obtain concentrate, the second-stage heavy sorting cryolite concentrate and the second-stage cryolite concentrate are combined to obtain cryolite concentrate, and the second-stage heavy sorting tailings and the second-stage tailings are combined to obtain sorted tailings.

[0006] Optionally, the particle size distribution range of the aluminum electrolysis residual anode fine particles is ≤3 mm.

[0007] Optionally, the screen mesh particle size of the first-stage screening classification screen is ≥0.5 mm.

[0008] Optionally, the heavy medium used in the first-stage heavy medium cyclone sorting comprises one or more of a magnetic iron / silicon iron powder aqueous solution, water glass, sodium phosphate, and polyacrylamide.

[0009] Optionally, the density of the heavy medium is 2.0 g / cm 3 ~2.8 g / cm 3 , and the conveying pressure of the heavy medium is 0.05 MPa~0.12 MPa.

[0010] Optionally, the heavy medium used in the second-stage heavy medium cyclone sorting comprises one or more of a magnetic iron / silicon iron powder aqueous solution, water glass, sodium phosphate, and polyacrylamide.

[0011] Optionally, the density of the heavy medium is 3.05 g / cm 3 ~3.35 g / cm 3 , and the conveying pressure of the heavy medium is 0.12 MPa~0.2 MPa.

[0012] Optionally, the feed concentration of the first-stage spiral chute sorting is 10%~20%.

[0013] Optionally, the second spiral chute sorting feed concentration is 15% to 25%.

[0014] Optionally, the method can meet: the carbon content of the refined carbon is 94% to 96.8%, the carbon recovery rate is 90.3% to 93.1%, and the cryolite purity of the cryolite concentrate is 90% to 92.5%.

[0015] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art: The embodiments of the present application provide a sorting method for aluminum electrolysis residual anode fine particles. First, the residual anode fine particles are split into oversize material (coarse particle level) and undersize material (fine particle level) according to particle size through the first screening classification, which avoids the problems of low separation accuracy and poor efficiency caused by poor equipment adaptability when coarse and fine particles are mixed and sorted, matches the "adapted material" for the subsequent sorting equipment from the source, and reduces the invalid processing link. Second, different sorting methods are used for different particle materials: the first heavy medium cyclone is used for the first screening oversize material of the coarse particle level, which can rely on centrifugal force to quickly separate carbon and high-density impurities and efficiently obtain coarse particle level refined carbon; the first spiral chute is used for the first screening undersize material of the fine particle level, which can accurately recover fine particle level refined carbon by using the gravity sedimentation difference of fine particle material, and the two form a "full particle size carbon recovery" system, which greatly reduces the loss of carbon resources and improves the recovery efficiency of the core product. Third, the intermediate tailings (first heavy separation tailings and first tailings) generated by sorting are directionally purified, and the cryolite in the coarse particle tailings is separated by the second heavy medium cyclone, and the cryolite in the fine particle tailings is separated by the second spiral chute, which not only avoids the waste of resources caused by directly discarding intermediate products, but also realizes the step-by-step separation of "carbon-cryolite-tailings", so that each step of sorting has a clear target and reduces process redundancy. Finally, through the product combining step, different particle size target products (refined carbon, cryolite concentrate, and tailings) of the same type are integrated to ensure that there is no missing target product in the whole process, forming a complete and efficient closed loop of "raw material input-step sorting-product output", and finally realizing the accurate and efficient separation of carbon, cryolite, and tailings in the residual anode fine particles. Thus, a high-efficiency sorting method for aluminum electrolysis residual anode fine particles is provided. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0018] Figure 1 A flowchart of a sorting method of aluminum electrolysis residual anode fine particles provided by the embodiment of the present application; Figure 2 An actual process schematic diagram of a sorting method of aluminum electrolysis residual anode fine particles provided by the embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0020] The range descriptions described herein, such as numerical range, ratio range, etc., include all possible sub-ranges and single values within the range, for example, the range description of "1 to 6" or "1-6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "include", "contain" and the like used herein mean "include but not limited to"; the relationship terms "first", "second" and the like are only used to distinguish different entities or operations, and do not imply actual sequence or relationship; "and / or" means that multiple cases can exist independently or simultaneously; "at least one", "multiple", "at least one" and the like refer to any combination of the corresponding objects, including single or multiple combinations of objects. The ratio relationship involved herein, such as mass ratio, molar ratio, etc., should be understood as the corresponding relationship between the front and rear terms in the ratio. The raw materials, reagents, instruments and equipment used herein can be purchased or prepared by existing methods.

[0021] Figure 1 A flowchart of a sorting method of aluminum electrolysis residual anode fine particles provided by the embodiment of the present application; Figure 2 An actual process schematic diagram of a sorting method of aluminum electrolysis residual anode fine particles provided by the embodiment of the present application.

[0022] As Figure 1 and Figure 2As shown, the embodiment of the present application provides a sorting method for aluminum electrolysis residual anode fine particles, which comprises: S1, the aluminum electrolysis residual anode fine particles are subjected to first-stage screening classification to obtain first-stage screen oversize and first-stage screen undersize; S2, the first-stage screen oversize is subjected to first heavy medium cyclone sorting to obtain first heavy sorting concentrate and first heavy sorting tailings; S3, the first-stage screen undersize is subjected to first spiral chute sorting to obtain first concentrate and first tailings; S4, the first heavy sorting tailings are subjected to second heavy medium cyclone sorting to obtain second heavy sorting cryolite concentrate and second heavy sorting tailings; S5, the first tailings are subjected to second spiral chute sorting to obtain second cryolite concentrate and second tailings; and S6, the first heavy sorting concentrate and the first concentrate are combined to obtain concentrate, the second heavy sorting cryolite concentrate and the second cryolite concentrate are combined to obtain cryolite concentrate, and the second heavy sorting tailings and the second tailings are combined to obtain sorted tailings.

[0023] It should be noted that the S1 step (first-stage screening classification) is the "preprocessing core" of the entire sorting process, and its core role is to accurately split the aluminum electrolysis residual anode fine particles (≤3 mm) according to particle size to obtain first-stage screen oversize (particle size ≥0.5 mm, coarse particle size) and first-stage screen undersize (particle size <0.5 mm, fine particle size). Since the subsequent sorting equipment has a clear adaptation requirement for the particle size of the material, the heavy medium cyclone is more suitable for processing coarse particles (to avoid the separation accuracy being reduced due to excessive carrying of fine particles by the medium), and the spiral chute is more suitable for fine particles (to realize efficient separation by utilizing the sedimentation difference of fine particles in the chute). Therefore, S1 classifies the material by particle size to match the "adapted material" for different sorting equipment from the source, avoids the problems of low efficiency and poor product purity caused by mixed sorting of coarse and fine particles, and is the basis for subsequent efficient sorting.

[0024] The S2 step (first heavy medium cyclone sorting of the first-stage screen oversize) assumes the role of "carbon enrichment of coarse particle size". The first-stage screen oversize is a mixture of coarse particle size impurities and carbon, and by utilizing the density difference between carbon (density 1.8-2.2 g / cm 3 ) and cryolite and tailings (density ≥2.9 g / cm 3 ), the low-density carbon particles are discharged with the "light product flow" in the cyclone under the action of the centrifugal force of the heavy medium cyclone, forming the first heavy sorting concentrate (coarse particle size concentrate); the high-density cryolite and tailings are discharged with the "heavy product flow", forming the first heavy sorting tailings. This step not only realizes efficient recovery of carbon in the coarse particle size, but also lays a "decarbonization" foundation for subsequent purification of cryolite, and at the same time, relies on the processing capacity of the heavy medium cyclone to ensure the sorting efficiency of the coarse particle size material.

[0025] S3 step (first spiral chute separation of first stage undersize) focuses on "fine particle level carbon enrichment", which is complementary to S2 to form "full particle size carbon recovery". The first stage undersize is fine particle material, and if heavy medium cyclone is used, fine particle carbon is easily lost due to being wrapped in the medium, while spiral chute can make fine particle carbon flow out with the upper layer flow in the chute through the difference in gravity settlement of fine particles (low carbon density and slow settlement, high impurity density and fast settlement), forming the first fine carbon (fine particle level fine carbon); fine particle impurities are discharged with the underflow, forming the first tailings. This step not only avoids the loss of fine particle carbon, but also reduces the processing cost of fine particle material through the low cost and low loss characteristics of spiral chute, and together with S2, it realizes full particle size coverage recovery of carbon in the residual anode.

[0026] S4 step (second heavy medium cyclone separation of first heavy separation tailings) is a key link for "coarse particle level cryolite purification". The first heavy separation tailings have removed coarse particle carbon, and the main components are coarse particle cryolite (density 2.9-3.0 g / cm 3 ) and coarse particle tailings (density > 3.0 g / cm 3 ). At this time, by adjusting the heavy medium parameters, the medium density cryolite is discharged with the light product flow of the cyclone to form the second heavy separation cryolite concentrate (coarse particle level cryolite); the high density tailings are discharged with the heavy product flow to form the second heavy separation tailings. This step realizes the directional recovery of cryolite in coarse particle impurities, and preliminarily separates the tailings that are difficult to utilize, improving the resource recovery value.

[0027] S5 step (second spiral chute separation of first tailings) undertakes the "fine particle level cryolite purification" function, and together with S4 forms a "full particle size cryolite recovery" system. The first tailings have removed fine particle carbon, and mainly contain fine particle cryolite and fine particle tailings. Through the settlement separation advantage of spiral chute for fine particle material, fine particle cryolite is discharged with a specific flow layer in the chute to form the second cryolite concentrate (fine particle level cryolite); fine particle tailings are discharged with the bottom flow to form the second tailings. This step not only avoids the waste of fine particle cryolite, but also, through cooperation with S4, realizes full particle size recovery of cryolite resources, further improving the resource utilization rate of fine particles in the residual anode.

[0028] The S6 step (product combination) is the "closed loop ending" link of the whole process, which functions to classify and integrate the target products of the whole process: the first reselected refined carbon (coarse-grained carbon) of S2 is combined with the first refined carbon (fine-grained carbon) of S3 to obtain a refined carbon product covering the whole particle size, avoiding carbon loss due to particle size difference and ensuring the recovery rate of refined carbon; the second reselected cryolite concentrate (coarse-grained cryolite) of S4 is combined with the second cryolite concentrate (fine-grained cryolite) of S5 to form a cryolite concentrate of the whole particle size, improving the recovery efficiency of cryolite; the second reselected tailings (coarse-grained tailings) of S4 are combined with the second tailings (fine-grained tailings) of S5 to realize the centralized collection of tailings, facilitating subsequent solid waste disposal. This step forms a complete closed loop of "raw material - separation - product" for the process, ensuring that each target product is not missed or mixed up.

[0029] In some embodiments, the particle size distribution range of the aluminum electrolysis residual anode fine particles is ≤3 mm.

[0030] Limiting the particle size distribution range of the aluminum electrolysis residual anode fine particles to ≤3 mm ensures that the core components such as carbon, cryolite, and tailings (e.g., aluminum oxide and iron sulfide) in the residual anode are fully dissociated, avoiding internal component wrapping due to large particles, which cannot be effectively separated by density difference. At the same time, a particle size of ≤3 mm perfectly matches the equipment characteristics of heavy medium cyclone (not easy to block the equipment when processing coarse particles, and the centrifugal force is more uniform) and spiral chute (the sedimentation difference is more significant when processing fine particles), neither causing equipment jamming due to too coarse particles nor causing material loss during the separation process due to too fine particles, laying a foundation for stable operation and high recovery rate of the whole process. For example, the particle size of the aluminum electrolysis residual anode fine particles can be 2.0 mm, 2.2 mm, 2.4 mm, 2.5 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, etc.

[0031] In some embodiments, the screen mesh particle size of the first-stage screening classification screen is ≥0.5 mm.

[0032] The screen mesh size of the first screening classification screen is ≥0.5 mm, which can clearly separate the material into a coarse particle level (screen oversize, ≥0.5 mm) and a fine particle level (screen undersize, <0.5 mm). For the coarse particle level screen oversize, the particle morphology is more suitable for centrifugal separation of the heavy medium cyclone, and the coarse particles are more obviously subjected to centrifugal force difference in the cyclone, so that the separation of carbon and high-density impurities can be quickly realized. For the fine particle level screen undersize, the particle size is highly consistent with the "gravity settling separation" characteristics of the spiral chute, which can avoid the loss of fine particles in the heavy medium cyclone and reduce the accumulation and blockage of fine particles in the chute. Through this classification, different particle sizes of the material enter the most suitable separation link, which reduces the separation interference from the source and improves the separation efficiency of the subsequent process. For example, the screen mesh size of the first screening classification screen can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, etc. In some embodiments, the heavy medium used in the first heavy medium cyclone separation includes one or more of a magnetic iron / silicon iron powder aqueous solution, water glass, sodium phosphate, and polyacrylamide.

[0033] In some embodiments, the density of the heavy medium is 2.0 g / cm 3 ~ 2.8 g / cm 3 , and the conveying pressure of the heavy medium is 0.05 MPa ~ 0.12 MPa.

[0034] In the first heavy medium cyclone separation link, one or more of a magnetic iron / silicon iron powder aqueous solution, water glass, sodium phosphate, and polyacrylamide is selected as the heavy medium. The magnetic iron / silicon iron powder aqueous solution is used to construct a medium system with adjustable density, which provides a carrier for subsequent density separation. Water glass and sodium phosphate are used to inhibit medium particle agglomeration, avoid separation deviation caused by uneven medium, and improve medium flowability by using polyacrylamide to reduce material retention in the cyclone, ensuring continuous and smooth separation process. The density of the heavy medium is set to 2.0 g / cm 3 ~ 2.8 g / cm 3 , which accurately matches the density of carbon (1.8 ~ 2.2 g / cm 3 ) and the density of cryolite and tailings (≥2.9 g / cm 3) density difference, so that the low-density carbon particles can be separated from the light product stream under the centrifugal force of the cyclone to form a first heavy selected carbon, and the high-density impurities enter the tailings, realizing efficient separation of carbon and impurities; the heavy medium conveying pressure is controlled at 0.05 MPa to 0.12 MPa, which can not only promote the medium and the coarse material to form a stable and suitable strength centrifugal flow field in the cyclone to ensure the separation efficiency, but also avoid the equipment wear and energy waste caused by excessive pressure. Ultimately, through the synergistic effect of various parameters, high-purity recovery of coarse carbon and economic and stable operation of the process are realized. For example, the heavy medium density of the first heavy medium cyclone separation can be 2.0 g / cm 3 , 2.1 g / cm 3 , 2.25 g / cm 3 , 2.4 g / cm 3 , 2.55 g / cm 3 , 2.6 g / cm 3 , 2.7 g / cm 3 , 2.8 g / cm 3 , etc.; the heavy medium conveying pressure of the first heavy medium cyclone separation can be 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.10 MPa, 0.11 MPa, 0.12 MPa, etc.

[0035] In some embodiments, the heavy medium used in the second heavy medium cyclone separation comprises one or more of a magnetic iron / silicon iron powder aqueous solution, water glass, sodium phosphate, and polyacrylamide.

[0036] In some embodiments, the heavy medium density is 3.05 g / cm 3 to 3.35 g / cm 3 , and the heavy medium conveying pressure is 0.12 MPa to 0.2 MPa.

[0037] In the second heavy medium cyclone separation process, one or more of the magnetic iron / silicon iron powder aqueous solution, water glass, sodium phosphate, and polyacrylamide used in the first heavy medium cyclone is selected as the heavy medium, which not only continues the stability and adaptability of the medium system, but also reduces the complexity and cost of process switching without additional adjustment of the medium type, and relies on the functional advantages of the system; the heavy medium density is set to 3.05 g / cm 3 to 3.35 g / cm 3 , which accurately matches the composition characteristics of the first selected tailings (mainly containing ice crystals and tailings), and the density is between ice crystals (2.9-3.0 g / cm 3 ) and tailings (density > 3.0 g / cm 3Between 0.12 MPa and 0.2 MPa, under the centrifugal force of the hydrocyclone, medium-density cryolite is smoothly separated into cryolite concentrate by the light product stream, while high-density tailings are discharged with the heavy product stream. This effectively prevents cryolite from mixing with the tailings or the tailings from contaminating the cryolite concentrate. The heavy medium conveying pressure is controlled between 0.12 MPa and 0.2 MPa, which is higher than the pressure of the first heavy medium cyclone separation. This pressure is suitable for the high density and denser particle characteristics of the tailings in the first heavy medium separation. The stronger pressure pushes the material to form a more stable and high-intensity centrifugal flow field, breaking the adhesion or mixing state of cryolite and tailings, maximizing the recovery rate and purity of the cryolite concentrate. Finally, through the synergistic effect of various parameters, the efficient purification of coarse-grained cryolite is achieved, laying a good foundation for subsequent product merging. For example, the density of the heavy medium in the second heavy medium cyclone separation can be 3.05 g / cm³. 3 3.1g / cm 3 3.15g / cm 3 3.2g / cm 3 3.25g / cm 3 3.3g / cm 3 3.32g / cm 3 3.35g / cm 3 The heavy medium conveying pressure for the second-stage medium cyclone separation can be 0.12MPa, 0.13MPa, 0.14MPa, 0.15MPa, 0.16MPa, 0.17MPa, 0.19MPa, 0.2MPa, etc.

[0038] In some embodiments, the feed concentration of the first spiral chute separator is 10% to 20%.

[0039] The feed concentration of the first spiral sluice is limited to 10%–20%, which allows fine particles to form a uniform flow layer within the sluice. This ensures that carbon particles have sufficient time to be discharged with the upper laminar flow due to their low density, while also preventing material accumulation, thus achieving efficient recovery and high-purity production of fine carbon. For example, the feed concentration of the first spiral sluice can be 10%, 12%, 13%, 14%, 15%, 16%, 18%, 20%, etc.

[0040] In some embodiments, the feed concentration of the second spiral chute separator is 15% to 25%.

[0041] The feed concentration for the second spiral sluice separation is limited to 15%–25%. The first tailings have had fine carbon removed and mainly contain fine cryolite and tailings. The density difference between the two is (cryolite 2.9 g / cm³). 3 ~3.0g / cm 3 Tailings > 3.0 g / cm³ 3) more significant; appropriately increasing the feed concentration to 15% ~ 25% can strengthen the sedimentation difference of fine particles in the chute. Cryolite is more likely to concentrate in the upper flow due to its slightly lower density, and the tailings are settled to the lower flow due to their high density, which not only avoids the decrease in processing efficiency caused by low concentration, but also improves the separation accuracy of cryolite and tailings through concentration optimization, ensuring high recovery rate of fine cryolite particles. For example, the feed concentration of the second spiral chute separation can be 15%, 17%, 18%, 20%, 23%, 25%, etc.

[0042] In some embodiments, the method can meet: the carbon content of the refined carbon is 94% ~ 96.8%, the carbon recovery rate is 90.3% ~ 93.1%, and the purity of the cryolite concentrate is 90% ~ 92.5%.

[0043] In summary, the aluminum electrolysis residual anode fine particle separation method proposed in the present application has multiple dimensions of significant advantages, and the overall process design is scientific and meets the actual needs of the industry.

[0044] From the process logic, it takes the material particle size and density characteristics as the core, and builds a complete process of "classification first, equipment adaptation, step-by-step purification, and product closed loop". Through the first stage of screening, the coarse and fine particle levels are accurately split, and different particle sizes are matched with the optimal separation scene of heavy medium cyclone (for coarse particles) and spiral chute (for fine particles), which avoids the low efficiency and poor purity caused by mixed separation from the source, and guarantees the separation accuracy of the whole process. In terms of resource recovery, this method realizes the full value mining of core resources in the residual anode, not only covering the recovery of carbon resources in the full particle size range, but also purifying cryolite directionally, avoiding the single recovery or waste of resources in traditional processing, significantly improving the resource utilization value of residual anode fine particles, and collecting tailings for subsequent disposal of solid waste.

[0045] From the perspective of environmental protection and economy, this process has outstanding advantages: no chemical reagents such as acid and alkali are used throughout the process, which fundamentally reduces the secondary pollution risk caused by chemical treatment, and meets the development direction of green solid waste disposal; the types of equipment used are simple and conventional, and the heavy medium system can be recycled and reused, without the need for complex consumables or high-cost equipment investment, which greatly reduces the processing cost of enterprises. In addition, the process has strong adaptability and operability, which can match the physical properties of residual anode fine particles and is easy to scale up and apply, effectively solving the problem of solid waste storage for enterprises, and providing a feasible path for enterprises to reduce costs and increase efficiency. Most importantly, this method innovatively applies gravity separation process to the disposal of aluminum electrolysis residual anode fine particles, filling the gap in related technologies and providing a new and efficient technical route for the resource utilization of residual anode solid waste in the industry.

[0046] The present application is further described below in connection with specific examples. The experimental methods in the following examples, unless otherwise specified, are generally determined according to national standards / industry standards / published content herein; if there is no corresponding national standard / industry standard / published content herein, it is determined according to the general international standard, the conventional condition or according to the condition suggested by the manufacturer.

[0047] Example 1 The present embodiment provides a high-efficiency sorting method for aluminum electrolysis residual anode fine particles carbon ash, which specifically comprises the following steps: (1) The aluminum electrolysis residual anode fine particles are subjected to first-stage screening classification, and the particle size of the residual anode fine particles raw material is ≤2 mm, to obtain first-stage screen oversize and first-stage screen undersize; (2) The first-stage screen oversize is subjected to first heavy medium cyclone sorting, and the first heavy medium is a water solution of silicon-iron powder, and the heavy medium density is 2.45 g / cm 3 , and the heavy medium conveying pressure is 0.1 MPa. After sorting, first heavy medium sorting concentrate and first heavy medium sorting tailings are obtained.

[0048] (3) The first-stage screen undersize is subjected to first spiral chute sorting, and the feed concentration of the first spiral chute sorting is 15%, to obtain first concentrate and first tailings; (4) The first heavy medium sorting tailings are subjected to second heavy medium cyclone sorting, and the second heavy medium is a mixed suspension of a water solution of silicon-iron powder and water glass, and the heavy medium density is 3.2 g / cm 3 , and the heavy medium conveying pressure is 0.18 MPa. Second heavy medium sorting cryolite concentrate and second heavy medium sorting tailings are obtained; (5) The first tailings are subjected to second spiral chute sorting, and the feed concentration of the second spiral chute sorting is 17%, to obtain second cryolite concentrate and second tailings; (6) The first heavy medium sorting concentrate and the first concentrate are combined to obtain concentrate, and the carbon content of the concentrate is 94%; the second heavy medium sorting cryolite concentrate and the second cryolite concentrate are combined to obtain cryolite concentrate, and the purity of the cryolite is 90%; and the second heavy medium sorting tailings and the second tailings are combined to obtain sorted tailings.

[0049] Example 2 The present embodiment provides a high-efficiency sorting method for aluminum electrolysis residual anode fine particles carbon ash, which specifically comprises the following steps: (1) The aluminum electrolysis residual anode fine particles are subjected to first-stage screening classification, and the particle size of the residual anode fine particles raw material is ≤2.5 mm, to obtain first-stage screen oversize and first-stage screen undersize; (2) The first-stage screen oversize is subjected to first heavy medium cyclone sorting, and the first heavy medium is a water solution of silicon-iron powder, and the heavy medium density is 2.38 g / cm 3, and the heavy medium conveying pressure is 0.08 MPa. The first heavy separation concentrate and the first heavy separation tailings are obtained after the separation.

[0050] (3) The first stage undersize is subjected to first spiral chute separation, the first spiral chute separation is conducted at a feed concentration of 14%, and the first concentrate and the first tailings are obtained; (4) The first heavy separation tailings are subjected to second heavy medium cyclone separation, the second heavy medium uses a mixed suspension of ferrosilicon powder aqueous solution and sodium phosphate, the heavy medium density is 3.15 g / cm 3 , and the heavy medium conveying pressure is 0.15 MPa. The second heavy separation cryolite concentrate and the second heavy separation tailings are obtained; (5) The first tailings are subjected to second spiral chute separation, the second spiral chute separation is conducted at a feed concentration of 21%, and the second cryolite concentrate and the second tailings are obtained; (6) The first heavy separation concentrate and the first concentrate are combined to obtain the concentrate, the carbon content of the concentrate is 96.3%, the second heavy separation cryolite concentrate and the second cryolite concentrate are combined to obtain the cryolite concentrate, the purity of the cryolite is 91.5%, and the second heavy separation tailings and the second tailings are combined to obtain the tailings after the separation.

[0051] Embodiment 3 The embodiment provides a high-efficiency separation method for aluminum electrolysis residual anode fine particle carbon ash, and specifically comprises the following steps. (1) The aluminum electrolysis residual anode fine particles are subjected to first stage screening classification, the particle size of the residual anode fine particles is ≤3 mm, and the first stage oversize and the first stage undersize are obtained; (2) The first stage oversize is subjected to first heavy medium cyclone separation, the first heavy medium uses a magnetic iron powder aqueous solution, the heavy medium density is 2 g / cm 3 , and the heavy medium conveying pressure is 0.05 MPa. The first heavy separation concentrate and the first heavy separation tailings are obtained after the separation.

[0052] (3) The first stage undersize is subjected to first spiral chute separation, the first spiral chute separation is conducted at a feed concentration of 10%, and the first concentrate and the first tailings are obtained; (4) The first heavy separation tailings are subjected to second heavy medium cyclone separation, the second heavy medium uses a mixed suspension of ferrosilicon powder aqueous solution and water glass, the heavy medium density is 3.05 g / cm 3 , and the heavy medium conveying pressure is 0.12 MPa. The second heavy separation cryolite concentrate and the second heavy separation tailings are obtained; (5) The first tailings are subjected to second spiral chute separation, the second spiral chute separation is conducted at a feed concentration of 18%, and the second cryolite concentrate and the second tailings are obtained; (6) the first heavy selected carbon concentrate and the first carbon concentrate are combined to obtain a carbon concentrate with a carbon content of 96.8%, the second heavy selected cryolite concentrate and the second cryolite concentrate are combined to obtain a cryolite concentrate with a purity of 92%, and the second heavy selected tailings and the second tailings are combined to obtain tailings after separation.

[0053] Example 4 The embodiment provides a high-efficiency separation method for carbon ash of aluminum electrolysis residual anode fine particles, and specifically comprises the following steps: (1) performing first-stage screening classification on the aluminum electrolysis residual anode fine particles, wherein the particle size of the residual anode fine particles is ≤3 mm, and first-stage screen oversize and first-stage screen undersize are obtained; (2) performing first heavy medium cyclone separation on the first-stage screen oversize, wherein a water solution of ferrosilicon powder is used as the first heavy medium, the density of the heavy medium is 2.68 g / cm 3 , and the heavy medium conveying pressure is 0.12 MPa, to obtain first heavy selected carbon concentrate and first heavy selected tailings.

[0054] (3) performing first spiral chute separation on the first-stage screen undersize, wherein the feeding concentration of the first spiral chute separation is 20%, to obtain first carbon concentrate and first tailings; (4) performing second heavy medium cyclone separation on the first heavy selected tailings, wherein a mixed suspension of a water solution of ferrosilicon powder and polyacrylamide is used as the second heavy medium, the density of the heavy medium is 3.3 g / cm 3 , and the heavy medium conveying pressure is 0.18 MPa, to obtain second heavy selected cryolite concentrate and second heavy selected tailings; (5) performing second spiral chute separation on the first tailings, wherein the feeding concentration of the second spiral chute separation is 22%, to obtain second cryolite concentrate and second tailings; (6) combining the first heavy selected carbon concentrate and the first carbon concentrate to obtain carbon concentrate with a carbon content of 96.6%, combining the second heavy selected cryolite concentrate and the second cryolite concentrate to obtain cryolite concentrate with a purity of 92.5%, and combining the second heavy selected tailings and the second tailings to obtain tailings after separation.

[0055] Example 5 The embodiment provides a high-efficiency separation method for carbon ash of aluminum electrolysis residual anode fine particles, and specifically comprises the following steps: (1) performing first-stage screening classification on the aluminum electrolysis residual anode fine particles, wherein the particle size of the residual anode fine particles is ≤3 mm, and first-stage screen oversize and first-stage screen undersize are obtained; (2) performing first heavy medium cyclone separation on the first-stage screen oversize, wherein a water solution of ferrosilicon powder is used as the first heavy medium, the density of the heavy medium is 2.8 g / cm 3, and the heavy medium conveying pressure is 0.12 MPa. The first heavy separation concentrate and the first heavy separation tailings are obtained after the separation.

[0056] (3) The first stage undersize is subjected to first spiral chute separation, and the first spiral chute separation is performed at a feed concentration of 18%, to obtain first concentrate and first tailings; (4) The first heavy separation tailings are subjected to second heavy medium cyclone separation, and the second heavy medium uses a mixed suspension of aqueous silicon-iron powder and polyacrylamide, and the heavy medium density is 3.35 g / cm 3 , and the heavy medium conveying pressure is 0.2 MPa. The second heavy separation cryolite concentrate and the second heavy separation tailings are obtained; (5) The first tailings are subjected to second spiral chute separation, and the second spiral chute separation is performed at a feed concentration of 25%, to obtain second cryolite concentrate and second tailings; (6) The first heavy separation concentrate and the first concentrate are combined to obtain concentrate, and the carbon content of the concentrate is 95.6%. The second heavy separation cryolite concentrate and the second cryolite concentrate are combined to obtain cryolite concentrate, and the purity of the cryolite is 90.5%. The second heavy separation tailings and the second tailings are combined to obtain tailings after the separation.

[0057] The carbon-containing material (concentrate) obtained after the first heavy medium cyclone separation and the first spiral chute separation is subjected to component determination, and the results are shown in Table 1. The cryolite material (cryolite concentrate) obtained after the second heavy medium cyclone separation and the second spiral chute separation is subjected to phase determination, and the results are shown in Table 2.

[0058] Table 1: Component results of the concentrate material

[0059] Table 2: Phase results of the cryolite material

[0060] As can be clearly seen from the data in Tables 1 and 2, the aluminum electrolysis residual anode fine particle separation method of the present application has a remarkable separation and purification effect on carbon and cryolite, and can effectively remove impurities, and the specific performance is as follows: As can be seen from Table 1 (result of fine carbon material composition), compared with the carbon content of 84.9% of the raw material, the carbon content of the fine carbon in Examples 1-5 is all increased to more than 94%, and the highest is 96.8%, and the carbon purity is obviously improved; at the same time, the impurities Na (1.45%) and Fe (0.88%) and F (5.21%) contained in the raw material are greatly reduced in the fine carbon, among which the content of Na is reduced to the lowest 0.045%, the content of Fe is reduced to the lowest 0.10%, and the content of F is reduced to the lowest 0.14%, and the impurity removal effect is outstanding. In addition, the carbon recovery rate of each example is kept at a high level of 90.3%-93.1%, which shows that while improving the carbon purity, the loss of carbon resources can be minimized to achieve efficient recovery of carbon.

[0061] As can be seen from Table 2 (result of cryolite material phase), the cryolite content in the tailing raw material is only 69.9%, and contains impurities such as aluminum oxide (15.1%), iron sulfide (8.5%) and carbon (3.8%), while the cryolite content of the cryolite concentrate in Examples 1-5 is all increased to more than 90%, and the highest is 92.5%, and the cryolite purity is significantly improved; especially, the aluminum oxide and iron sulfide which account for a certain proportion in the raw material are completely removed in the cryolite concentrate of each example, only a small amount of carbon and calcium fluoride is left, and the carbon content is reduced from 3.8% in the raw material to the lowest 2.9%, which further proves that the method can accurately separate cryolite from other impurities and realize directional purification of cryolite.

[0062] From the data of the two tables, it can be seen that the sorting method of the present application can not only efficiently improve the purity and recovery rate of carbon, but also greatly improve the purity of cryolite and remove the main impurities, realizing efficient separation of carbon and cryolite in the residual anode fine particles and high-value recovery of resources, fully verifying the effectiveness and practicability of the sorting method.

[0063] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages: In the embodiments of the present application, the gravity separation process more suitable for the properties of the residual anode is innovatively introduced, the main components in the residual anode fine particles are carbon, and the impurity components are mainly cryolite, iron sulfide, aluminum oxide and the like, and the densities of the three are quite different, so the efficient separation of carbon-ash and cryolite-ash can be realized through the density difference of the materials.

[0064] In the embodiments of the present application, the carbon components and impurity elements in the aluminum electrolysis residual anode fine particles, and the cryolite and impurity components can be efficiently separated, which has low cost, simple equipment, does not use acid and alkali, high product purity, better adaptability of processing efficiency, is easy to dispose on a large scale, and provides an effective process route for reducing enterprise cost, reducing solid waste storage, and improving the value of aluminum electrolysis residual anode fine particles. At present, there is no research on applying the gravity separation process to dispose aluminum electrolysis residual anode fine particles.

[0065] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A method for sorting fine particles from residual anode material in aluminum electrolysis, characterized in that, The method includes: The fine particulate matter from the residual anode of aluminum electrolysis is subjected to a first-stage sieve classification to obtain the first-stage oversize and the first-stage undersize. The material over the first section of the screen is subjected to a first-stage medium cyclone separation to obtain first-stage refined carbon and first-stage tailings. The first section of undersize material is separated by a first spiral chute to obtain the first refined carbon and the first tailings. The first gravity separation tailings are subjected to a second medium cyclone separation to obtain second gravity cryolite concentrate and second gravity separation tailings. The first tailings are separated by a second spiral sluice to obtain a second cryolite concentrate and a second tailings residue; and The first heavy separation concentrate and the first refined carbon are combined to obtain refined carbon. The second heavy separation cryolite concentrate and the second cryolite concentrate are combined to obtain cryolite concentrate. The second heavy separation tailings and the second tailings are combined to obtain the sorted tailings.

2. The method according to claim 1, characterized in that, The particle size distribution range of the fine particles from the aluminum electrolysis residual anode is ≤3mm.

3. The method according to claim 1, characterized in that, The screen particle size of the first stage screening and grading screen is ≥0.5mm.

4. The method according to claim 1, characterized in that, The heavy medium used in the first heavy medium cyclone separation includes one or more of the following: magnetic / ferrosilicon powder aqueous solution, water glass, sodium phosphate, and polyacrylamide.

5. The method according to claim 4, characterized in that, The density of the heavy medium is 2.0 g / cm³. 3 ~2.8g / cm 3 The conveying pressure of heavy media is 0.05MPa~0.12MPa.

6. The method according to claim 1, characterized in that, The heavy medium used in the second heavy medium cyclone separation includes one or more of the following: magnetic / ferrosilicon powder aqueous solution, water glass, sodium phosphate, and polyacrylamide.

7. The method according to claim 6, characterized in that, The density of the heavy medium is 3.05 g / cm³. 3 ~3.35g / cm 3 The conveying pressure of heavy media is 0.12MPa~0.2MPa.

8. The method according to claim 1, characterized in that, The feed concentration for the first spiral chute separation is 10% to 20%.

9. The method according to claim 1, characterized in that, The feed concentration for the second spiral chute separation is 15% to 25%.

10. The method according to claim 1, characterized in that, The method can satisfy the following: the carbon content of the refined carbon is 94% to 96.8%, the carbon recovery rate is 90.3% to 93.1%, and the cryolite purity of the cryolite concentrate is 90% to 92.5%.

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