A method for upgrading high-ash aluminum electrolytic fine residue by flotation

Abstract

The application provides a flotation upgrading method for high-ash aluminum electrolysis fine residue, and belongs to the field of solid waste resource recovery. The method comprises the following steps: ball milling the high-ash aluminum electrolysis fine residue to obtain ultra-fine particle material; slurry conditioning is performed on the ultra-fine particle material to obtain first slurry; a surfactant is added to the first slurry for pre-dispersion treatment to obtain second slurry; a composite collector and a foaming agent are added to the second slurry for roughing flotation to obtain roughing carbon slurry and roughing tailings; the roughing carbon slurry is subjected to slurry conditioning to obtain third slurry; the composite collector and the foaming agent are added to the third slurry for cleaning flotation to obtain cleaning carbon slurry and cleaning tailings; an inhibitor is added to the cleaning carbon slurry for reverse flotation to obtain low-ash fine carbon. Through the cooperation of the process steps, the fine particle mud agglomeration of the high-ash aluminum electrolysis fine residue is broken, the surface impurities are efficiently removed, and the carbon and inorganic impurities are deeply separated, so that the low-ash high-purity fine carbon is finally obtained.

Description

Technical Field

[0001] This application relates to the field of solid waste resource recycling technology, and in particular to a flotation method for improving the quality of fine residues from high-ash aluminum electrolysis. Background Technology

[0002] In the aluminum electrolysis production process, the anode carbon block needs to be replaced periodically, and the remaining part after being lifted out is called the residual electrode. The residual electrode is mainly composed of carbonaceous material, electrolyte, and a small amount of metallic impurities. After cleaning, crushing, and screening, the residual electrode is divided into two categories according to particle size: large-particle residual electrodes with a particle size greater than three millimeters have an intact structure and impurities are mainly attached to the surface, making them easy to sort and reuse; while fine-particle residual electrodes with a particle size less than three millimeters accumulate a large amount of impurities such as fluorine, sodium, and iron due to electrolyte penetration during long-term use, making them extremely difficult to sort.

[0003] The impurity content of fine-grained aluminum electrolytic residues directly affects the ash and trace element indicators of prebaked anodes. Direct reuse without treatment will exacerbate the oxidation catalytic effect of carbon anodes, hindering the quality of aluminum products. Currently, fine residues account for approximately 20% of the aluminum electrolytic residues produced per ton of aluminum. Assuming my country's electrolytic aluminum production exceeds 45 million tons by 2025, the annual production of fine residues will be approximately 900,000 tons. However, current processing methods primarily involve stockpiling or low-price sales, resulting in significant resource waste. Therefore, providing an efficient, short-process method for improving the quality of fine residues from aluminum electrolysis is a pressing issue that needs to be addressed in this field. Summary of the Invention

[0004] This application provides a flotation method for improving fine residues from high-grey aluminum electrolysis, which is an efficient, short-process method suitable for improving fine residues from aluminum electrolysis.

[0005] This application provides a flotation method for upgrading fine residues from high-grey aluminum electrolysis, the method comprising: High-gray aluminum electrolytic fine residues were ball-milled to obtain ultrafine particles. The ultrafine particles are mixed with water to form a slurry, thus obtaining the first slurry. A surfactant is added to the first slurry for pre-dispersion treatment to obtain a second slurry; A composite collector and a frother are added to the second slurry for roughing flotation to obtain roughing carbon slurry and roughing tailings. The coarse carbon slurry is adjusted to obtain a third slurry; The composite collector and the frother are added to the third slurry for fine flotation to obtain fine carbon slurry and fine tailings, and the fine tailings are returned to the roughing flotation process. An inhibitor is added to the selected carbon slurry to perform reverse flotation and obtain low-ash refined carbon; The composite collector is composed of a hydrocarbon oil collector and a non-polar modifier. The hydrocarbon oil collector includes at least one of kerosene, diesel oil, or methyl isobutyl methanol, and the non-polar modifier includes at least one of dodecylbenzene, octadecylsilane, or octadecyl alcohol. The foaming agent includes at least one of pine oil or methyl pentanol.

[0006] Optionally, the ball milling method is dry milling; The proportion of ultrafine particles with a particle size of 200 mesh or less is 75% to 80%. The mass concentration of the first slurry is 20% to 35%.

[0007] Optionally, the surfactant is ethanol, and the volume of the surfactant is 1% to 3% of the volume of the first slurry.

[0008] Optionally, the pre-dispersion treatment is ultrasonic dispersion, and the ultrasonic dispersion includes the following parameters: temperature is room temperature, ultrasonic power is 200W to 300W, and ultrasonic time is 5min to 10min.

[0009] Optionally, the mass ratio of the hydrocarbon oil collector to the nonpolar modifier is (5-10):1.

[0010] Optionally, during the roughing flotation process, the amount of the composite collector added is 600 g / t-raw ore to 1400 g / t-raw ore, and the amount of the frother added is 0 g / t-raw ore to 100 g / t-raw ore. The roughing flotation includes the following parameters: air flow rate is 1 m³ / s. 3 / min~2m 3 The stirring speed is 1800 rpm to 2200 rpm, and the stirring time is 2 min to 4 min.

[0011] Optionally, during the refined flotation process, the amount of the composite collector added is 0 g / t-raw ore to 400 g / t-raw ore, and the amount of the frother added is 0 g / t-raw ore to 100 g / t-raw ore. The selective flotation includes the following parameters: air flow rate is 1 m³ / s. 3 / min~1.5m 3 The stirring speed is 2000 rpm to 2300 rpm, and the stirring time is 3 min to 5 min.

[0012] Optionally, the mass concentration of the third slurry is 15% to 20%.

[0013] Optionally, the inhibitor is water glass or tannin, and the amount of inhibitor added is 50g / t-raw ore to 200g / t-raw ore.

[0014] Optionally, the reverse flotation includes the following parameters: air flow rate of 1 m³ / min. 3 / min~2m 3 The stirring speed is 2100 rpm to 2200 rpm, and the stirring time is 3 min to 5 min.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a flotation method for improving the quality of fine residues from high-ash aluminum electrolysis. Through a series of synergistic process steps, it achieves the breaking down of fine-particle mud-like agglomerates in the fine residues from high-ash aluminum electrolysis, the efficient removal of surface impurities, and the deep separation of carbonaceous and inorganic impurities, ultimately obtaining low-ash, high-purity refined carbon.

[0016] Regarding the removal of fine-grained mud-like agglomerates, this application first uses ball milling to process high-ash aluminum electrolytic residues into ultrafine particles, enabling the carbonaceous material and long-term permeated electrolyte impurities to fully dissociate at the physical level, laying the foundation for subsequent separation. Based on this, a surfactant is added to the first slurry and pre-dispersed. Utilizing the permeation effect of the surfactant and the cavitation effect of ultrasound, non-selective agglomerates between fine particles are effectively destroyed, and the fine mud adhering to the carbonaceous surface is washed away, restoring the carbonaceous particles to their clean, original surface, thereby completely eliminating the interference of fine-grained mud-like agglomerates on the flotation process.

[0017] In terms of efficient removal of surface impurities, the pre-dispersion treatment not only breaks up agglomerates, but more importantly, it removes the electrolyte film and adhering impurities that have accumulated on the carbonaceous surface over a long period of time, allowing these impurities to exist in the slurry in an independently dispersed form. Subsequently, in the roughing and cleaning flotation processes, the selective adsorption of carbonaceous particles by the composite collector makes the clean carbonaceous surface hydrophobic and floats into the froth product, while the removed hydrophilic inorganic impurities remain in the slurry or tailings, achieving efficient separation of surface impurities from carbonaceous matter.

[0018] In terms of efficient separation of carbonaceous material and inorganic impurities, this application constructs a multi-stage flotation separation system. The roughing flotation stage employs a composite collector composed of a hydrocarbon oil collector and a non-polar modifier, exhibiting excellent collecting ability and selectivity for fine carbon particles, achieving the main separation of carbonaceous material and inorganic impurities. The carbon slurry obtained from the roughing stage is then subjected to cleaning flotation after slurry conditioning. A low-concentration environment reduces the slurry viscosity, minimizing non-selective entrainment of impurity particles and further improving the concentrate grade. The design of returning the cleaning tailings to the roughing process not only recovers intermediate-quality carbonaceous material but also ensures the overall recovery rate. Finally, by adding inhibitors to the cleaning carbon slurry for reverse flotation, the floatability of residual inorganic impurities is selectively suppressed, achieving a final deep separation of carbonaceous material and impurities, ensuring the high purity of the obtained low-ash concentrate.

[0019] In obtaining low-ash, high-purity refined carbon, through the progressive separation and purification steps described above, the fixed carbon content in the final product is significantly increased, and harmful impurities such as sodium fluoride are efficiently removed, fully meeting the requirements for the use of high-quality carbon raw materials.

[0020] Regarding energy consumption and cost control, this application employs physical and physicochemical methods throughout the process, eliminating the need for highly corrosive chemical reagents such as acids and alkalis. This avoids complex wastewater treatment systems and investment in corrosion-resistant equipment, significantly reducing operating costs and environmental pressure. The process flow design is compact, with smooth transitions between steps and mild operating conditions, facilitating continuous industrial production. Attached Figure Description

[0021] 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.

[0022] 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.

[0023] Figure 1 This is a schematic flowchart of a flotation method for improving fine residues from high-grey aluminum electrolysis, provided in an embodiment of this application. Detailed Implementation

[0024] 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.

[0025] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1 to 6" cover 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 "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0026] Figure 1 This is a schematic flowchart of a flotation method for improving fine residues from high-grey aluminum electrolysis, provided in an embodiment of this application.

[0027] like Figure 1 As shown in the embodiment of this application, a flotation method for improving the fine residues from high-grey aluminum electrolysis is provided. The method includes: S1. The high-gray aluminum electrolytic fine residue is ball-milled to obtain ultrafine particle material; S2. Mix the ultrafine particles with water to form a slurry, thus obtaining the first slurry; S3. Add surfactant to the first slurry for pre-dispersion treatment to obtain the second slurry; S4. Add a composite collector and a frother to the second slurry to carry out roughing flotation to obtain roughing carbon slurry and roughing tailings. S5. The coarse carbon slurry is adjusted to obtain the third slurry; S6. Add composite collector and frother to the third slurry for fine flotation to obtain fine carbon slurry and fine tailings, and return the fine tailings to the roughing flotation process; S7. Add inhibitors to the selected carbon slurry to perform reverse flotation and obtain low-ash refined carbon; The composite collector is composed of a hydrocarbon oil collector and a non-polar modifier. The hydrocarbon oil collector includes at least one of kerosene, diesel oil, or methyl isobutyl methanol, and the non-polar modifier includes at least one of dodecylbenzene, octadecylsilane, or octadecyl alcohol. The foaming agent includes at least one of pine oil or methyl pentanol.

[0028] It should be noted that this application solves the technical problems of fine particle mud interference, selective recovery of micro-fine carbon particles, and deep purification of concentrate by a series of logically progressive steps, such as ball milling and dissociation, surfactant pre-dispersion and cleaning, composite collector-enhanced roughing, low-concentration fine cleaning and purification, middlings recycling and recovery, and inhibitor reverse flotation deep purification. Ultimately, it achieves the goal of efficiently recovering low-ash fine carbon from high-ash aluminum electrolytic fine residues.

[0029] Firstly, the high-ash aluminum electrolytic fine residue is treated by ball milling, which further grinds the raw material to an ultrafine particle size. This process aims to break down agglomerates formed in the fine residue due to long-term electrolytic wetting, allowing the electrolyte and ash impurities encased within the carbonaceous material to fully dissociate. More importantly, it controls the particle size within a specific range, creating the necessary particle size conditions for subsequent flotation separation and ensuring that carbonaceous particles and impurity particles are physically separated into individual particles.

[0030] Next, the ultrafine particles obtained from grinding are mixed with water to form the first slurry. The purpose of this step is to construct a liquid-solid dispersion system suitable for flotation operations, providing a uniform medium environment for the subsequent addition of reagents and the interaction of particles.

[0031] Subsequently, a surfactant is added to the first slurry and pre-dispersed to obtain the second slurry. This step is a crucial pretreatment step in the entire method. Its core function is to utilize the chemical action and physical energy input of the surfactant to further eliminate non-selective agglomeration and mud-like covering phenomena among fine particles, that is, to reduce the interference and contamination of fine mud on the surface of carbonaceous particles. This effectively cleans and exposes the true surface of carbonaceous particles, enhancing the difference in surface properties between the target carbonaceous material and inorganic impurity particles, laying a clean surface foundation for the selective adsorption of subsequent flotation reagents.

[0032] After pretreatment, a composite collector consisting of a hydrocarbon oil collector and a non-polar modifier, along with a frother, is added to the second slurry for roughing flotation. This step aims to achieve the main separation of carbonaceous materials from inorganic impurities. The hydrocarbon oil component in the composite collector enhances the hydrophobicity of the fine carbon particles, while the non-polar modifier, targeting the high ash and fine residue characteristics, improves the collector's selective capture ability for fine carbon particles, recovering carbonaceous material while suppressing impurity flotation. The frother generates a stable foam layer, carrying hydrophobic carbonaceous particles with attached bubbles into the foam product, forming the roughing carbon slurry. The hydrophilic inorganic impurities remain in the slurry and are discharged as roughing tailings.

[0033] After obtaining the roughing carbon slurry, it is adjusted to a suitable concentration to obtain the third slurry. This process reduces the slurry concentration, creating a separation environment more conducive to improving concentrate grade in the cleaning operation. Subsequently, a composite collector and frother are added to the third slurry for cleaning flotation. This further purifies the roughing carbon slurry, removing impurities through a second flotation to obtain a higher purity cleaning carbon slurry. The cleaning tailings generated during this process, still containing a certain amount of carbonaceous material, are returned to the roughing flotation process. This recycling step recovers this intermediate-quality carbonaceous material, avoiding resource loss and improving the overall recovery rate of the process.

[0034] Finally, inhibitors are added to the selected carbon slurry for reverse flotation, which is the final deep purification step. Its function is to selectively suppress residual inorganic impurity particles with similar surface properties to the carbonaceous material or those difficult to separate in upstream steps, causing them to become hydrophilic and settle to the bottom of the tank, while the target carbonaceous product continues to float and be collected, thus obtaining the final low-ash refined carbon. Through reverse flotation, secondary purification and impurity removal of the selected carbon slurry are achieved, ensuring that the ash content of the final refined carbon product meets high-quality requirements.

[0035] In some implementations, the ball milling method is dry milling; The proportion of ultrafine particles with a particle size of 200 mesh or less is 75% to 80%. The mass concentration of the first slurry is 20% to 35%.

[0036] Dry grinding avoids the pre-wetting of fine particles by water and the introduction of additional impurities by the media during wet grinding, ensuring the stability of the material's surface properties after grinding. Controlling the particle size of ultrafine materials to 75%–80% of 200 mesh or smaller allows for sufficient dissociation of carbonaceous material from encapsulated electrolyte impurities, while preventing secondary mudding caused by excessively fine grinding. The mass concentration of the first slurry is set at 20%–35%. This range maintains good slurry flowability for subsequent transport and preparation, while ensuring uniform dispersion of reagents in the slurry, creating suitable concentration conditions for flotation separation. For example, the proportion of 200 mesh or smaller can be 75%, 75.5%, 76%, 77%, 78%, 78.5%, 79%, 80%, etc., and the mass concentration of the first slurry can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 35%, etc.

[0037] In some embodiments, the surfactant is ethanol, and the volume of the surfactant is 1% to 3% of the volume of the first slurry.

[0038] Ethanol, as a surfactant, can effectively reduce the surface tension of the slurry, penetrate into the gaps between fine particles, and assist ultrasonic energy in breaking down the adhesion of fine mud to the carbonaceous surface. Its addition amount is controlled at 1%–3% of the first slurry volume. This ensures sufficient dispersion of fine aggregates while avoiding excessive surfactant interference with subsequent collector adsorption, thus guaranteeing precise control of the carbonaceous surface properties. For example, the surfactant volume percentage can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.6%, 3%, etc.

[0039] In some embodiments, the pre-dispersion treatment is ultrasonic dispersion, which includes the following parameters: room temperature, ultrasonic power of 200W to 300W, and ultrasonic time of 5min to 10min.

[0040] The ambient temperature setting avoids the impact of temperature changes on the inherent surface properties of the material; the ultrasonic power of 200W to 300W generates sufficient cavitation effect and mechanical force to effectively break up soft agglomerates between fine particles and the adhesion layer of impurities on the surface of carbon particles; the ultrasonic time of 5min to 10min ensures that the slurry system is fully and uniformly dispersed, allowing carbonaceous and impurity particles to remain in independent suspension, laying a clean surface foundation for the selective action of subsequent flotation reagents. For example, the ultrasonic power can be 200W, 220W, 240W, 250W, 260W, 280W, 290W, 300W, etc., and the ultrasonic time can be 5min, 6min, 7min, 7.5min, 8min, 8.5min, 9min, 10min, etc.

[0041] In some embodiments, the mass ratio of hydrocarbon oil collector to nonpolar modifier is (5-10):1.

[0042] Combining hydrocarbon oil collectors with nonpolar modifiers at a mass ratio of 5:1 to 10:1 can balance the collector's ability and selectivity in capturing fine carbon particles. The hydrocarbon oil provides basic hydrophobic adsorption, while the nonpolar modifier further enhances the spreading and fixation of the agent on the carbonaceous surface, specifically targeting the high ash and fine residue characteristics of the material. This results in sufficient and uniform hydrophobicity for the carbon particles, while reducing non-specific adsorption of inorganic impurities, thus achieving efficient preliminary separation of carbon and impurities in the roughing stage. For example, the mass ratio of hydrocarbon oil collector to nonpolar modifier can be 5:1, 6:1, 6.5:1, 7:1, 8:1, 8.5:1, 9:1, 10:1, etc.

[0043] In some implementations, during the roughing flotation process, the amount of compound collector added is 600 g / t-raw ore to 1400 g / t-raw ore, and the amount of frother added is 0 g / t-raw ore to 100 g / t-raw ore. The roughing flotation includes the following parameters: air flow rate of 1 m³ / s. 3 / min~2m 3 The stirring speed is 1800 rpm to 2200 rpm, and the stirring time is 2 min to 4 min.

[0044] A composite collector dosage of 600 g / t to 1400 g / t is sufficient to cover the surface of fine carbon particles and impart adequate hydrophobicity; a foaming agent dosage controlled between 0 and 100 g / t allows for flexible adjustment of the foam layer thickness and stability to adapt to different raw material properties; 1m 3 / min~2m 3 An aeration flow rate of / min can generate an appropriate number of bubbles, ensuring effective collision between carbon particles and bubbles; a stirring speed of 1800rpm to 2200rpm promotes slurry turbulence, enhances the mixing of particles and reagents, and the dispersion of bubbles; a stirring time of 2min to 4min allows hydrophobic carbon particles sufficient opportunity to adhere to bubbles and float into the foam layer, while avoiding excessive stirring that could cause separated impurities to be mixed in again. For example, the dosage of the compound collector can be 600 g / t of raw ore, 700 g / t of raw ore, 850 g / t of raw ore, 1000 g / t of raw ore, 1150 g / t of raw ore, 1250 g / t of raw ore, 1300 g / t of raw ore, 1400 g / t of raw ore, etc., and the dosage of the foaming agent can be 0 g / t of raw ore, 20 g / t of raw ore, 35 g / t of raw ore, 50 g / t of raw ore, 65 g / t of raw ore, 75 g / t of raw ore, 90 g / t of raw ore, 100 g / t of raw ore, etc., and the aeration flow rate can be 1 m³ / t. 3 / min, 1.2m 3 / min, 1.4m 3 / min, 1.5m 3 / min, 1.6m 3 / min, 1.8m 3 / min, 1.9m 3 / min, 2m 3 The stirring speed can be 1800rpm, 1900rpm, 2000rpm, 2050rpm, 2100rpm, 2150rpm, 2180rpm, 2200rpm, etc., and the stirring time can be 2min, 2.5min, 3min, 3.2min, 3.5min, 3.7min, 3.9min, 4min, etc.

[0045] In some implementations, during the fine flotation process, the amount of compound collector added is 0 g / t-raw ore to 400 g / t-raw ore, and the amount of frother added is 0 g / t-raw ore to 100 g / t-raw ore. The fine flotation process includes the following parameters: air flow rate of 1 m³ / s. 3 / min~1.5m 3 The stirring speed is 2000 rpm to 2300 rpm, and the stirring time is 3 min to 5 min.

[0046] In some embodiments, the mass concentration of the third slurry is 15% to 20%.

[0047] In the refining stage, a lower slurry concentration of 15%–20% is used to significantly reduce slurry viscosity and decrease non-selective entrainment; a composite collector of 0–400 g / t is used to supplement and enhance the hydrophobicity of carbon particles; a foaming agent of 0–100 g / t is used to maintain a suitable foam layer; and the aeration flow rate is reduced to 1 m³ / t. 3 / min~1.5m 3 The stirring speed of 2000 rpm to 2300 rpm helps to improve the selectivity of bubbles and avoid mechanically entraining impurity particles into the foam; the high stirring speed of 2000 rpm to 2300 rpm ensures that the slurry is fully suspended and the reagent is evenly dispersed; the stirring time of 3 min to 5 min ensures that impurities and carbon particles are fully separated at low concentrations, thereby obtaining a higher grade of refined carbon slurry. For example, the dosage of the compound collector can be 0 g / t of raw ore, 50 g / t of raw ore, 100 g / t of raw ore, 150 g / t of raw ore, 200 g / t of raw ore, 250 g / t of raw ore, 350 g / t of raw ore, 400 g / t of raw ore, etc., and the dosage of the foaming agent can be 0 g / t of raw ore, 15 g / t of raw ore, 30 g / t of raw ore, 45 g / t of raw ore, 60 g / t of raw ore, 70 g / t of raw ore, 95 g / t of raw ore, 100 g / t of raw ore, etc., and the aeration flow rate can be 1 m³ / t. 3 / min, 1.1m 3 / min, 1.2m 3 / min, 1.3m 3 / min, 1.35m 3 / min, 1.4m 3 / min, 1.45m 3 / min, 1.5m 3 The stirring speed can be 2000 rpm, 2050 rpm, 2100 rpm, 2150 rpm, 2200 rpm, 2220 rpm, 2250 rpm, 2300 rpm, etc., and the stirring time can be 3 min, 3.5 min, 4 min, 4.2 min, 4.5 min, 4.7 min, 4.9 min, 5 min, etc., and the mass concentration of the third slurry can be 15%, 16%, 16.5%, 17%, 18%, 18.5%, 19%, 20%, etc.

[0048] In some implementations, the inhibitor is water glass or tannin, and the amount of inhibitor added is 50g / t-raw ore to 200g / t-raw ore.

[0049] Water glass or tannins, acting as inhibitors, can selectively adsorb onto the surface of inorganic impurities such as silicates and fluorides, enhancing their hydrophilicity and causing them to remain in the slurry. An addition amount of 50 g / t to 200 g / t can effectively inhibit impurity flotation without affecting the natural hydrophobicity of the carbon particles and the adsorbed collector, thus achieving deep separation of carbon and impurities during reverse flotation. For example, the amount of inhibitor added can be 50 g / t of raw ore, 70 g / t of raw ore, 90 g / t of raw ore, 110 g / t of raw ore, 130 g / t of raw ore, 150 g / t of raw ore, 180 g / t of raw ore, 200 g / t of raw ore, etc.

[0050] In some implementations, reverse flotation includes the following parameters: air flow rate of 1 m³ / s. 3 / min~2m 3 The stirring speed is 2100 rpm to 2200 rpm, and the stirring time is 3 min to 5 min.

[0051] 1m 3 / min~2m 3An aeration flow rate of 1 m³ / min provides an appropriate amount of air bubbles to carry the refined carbon to the surface, while impurities acting as inhibitors remain at the bottom of the tank due to their hydrophilic nature. A high stirring speed of 2100 rpm to 2200 rpm ensures sufficient contact between the inhibitors and impurities and guarantees uniformity throughout the slurry system. A stirring time of 3 to 5 minutes is sufficient for the refined carbon to complete its final flotation separation, while ensuring that impurities are adequately suppressed and not carried by the air bubbles, thereby obtaining low-ash refined carbon with an ash content of less than 5%. For example, the aeration flow rate can be 1 m³ / min. 3 / min, 1.2m 3 / min, 1.4m 3 / min, 1.5m 3 / min, 1.6m 3 / min, 1.8m 3 / min, 1.9m 3 / min, 2m 3 The stirring speed can be 2100rpm, 2120rpm, 2140rpm, 2150rpm, 2160rpm, 2180rpm, 2190rpm, 2200rpm, etc., and the stirring time can be 3min, 3.5min, 4min, 4.2min, 4.5min, 4.7min, 4.9min, 5min, etc.

[0052] In summary, this application provides a flotation method for improving the quality of fine residues from high-ash aluminum electrolysis, which achieves the removal of fine-particle mud-like agglomeration, efficient removal of surface impurities, and efficient separation of carbonaceous and inorganic impurities, ultimately obtaining low-ash, high-purity refined carbon. The process has low energy consumption, low cost, and a short process flow that is easy to industrialize.

[0053] This application significantly reduces the interference of fine mud by pretreating the slurry, enhances the differences in surface properties of the target product, and improves the selectivity and collecting power of fine carbon particles in high-ash fine residue by using a composite collector, thereby improving the grade of refined carbon. At the same time, the low-concentration beneficiation and depressant reverse flotation in the process effectively achieve further impurity removal and quality improvement (secondary purification) of refined carbon.

[0054] The method described in this application can obtain low-ash aluminum electrolytic fine residues with a fixed carbon content of over 97% and a refined carbon yield of over 50% from high-ash fine residues with a fixed carbon content of less than 80%. The process is short and stable, avoids the corrosion of equipment and waste liquid treatment problems caused by acid and alkali removal, and achieves efficient quality improvement of high-ash aluminum electrolytic fine residues, resulting in significant economic benefits.

[0055] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0056] Example 1 This embodiment provides a flotation method for upgrading fine residues from high-grey aluminum electrolysis, specifically including the following steps: (1) The high-ash aluminum electrolytic fine residue was ball-milled and passed through a 200-mesh sieve to obtain ultrafine particles with a particle size of 200 mesh or less accounting for 76%; (2) Weigh 120g of ultrafine particle material and mix the ultrafine particle material with water to prepare a first slurry with a mass concentration of 20%; (3) The first slurry was pre-dispersed in an ultrasonic instrument, and 1% of the volume of the first slurry was added as a surfactant. The temperature was room temperature, the ultrasonic power was 200W, and the ultrasonic time was 5min to obtain the second slurry. (4) Add a composite collector and a frother to the second slurry for roughing flotation. The composite collector is added at a rate of 600 g / t of raw ore and is composed of kerosene and octadecyl alcohol in a mass ratio of 5:1. The frother is pine oil and is added at a rate of 33.3 g / t of raw ore. The roughing flotation conditions are: air flow rate 1 m³ / t. 3 Stirring speed 2200 rpm for 2 minutes to allow the composite collector to fully act, then add the foaming agent and continue stirring for 2 minutes to obtain rough carbon slurry and rough tailings. (5) Add water to the roughing carbon slurry to adjust the slurry concentration to 15% to obtain the third slurry; add a composite collector and a frother to the third slurry for fine flotation. The ratio of the composite collector and the type of frother are the same as those for the roughing flotation, wherein the amount of composite collector added is 200 g / t-raw ore and the amount of frother added is 100 g / t-raw ore; the fine flotation conditions are: aeration flow rate 1.2 m 3 The stirring speed is 2000 rpm and the stirring time is 3 min. The refined carbon slurry and refined tailings are obtained, and the refined tailings are returned to the roughing flotation process to realize the recycling of intermediate quality carbon slurry. (6) Add an inhibitor to the selected carbon slurry for reverse flotation. The inhibitor is water glass, and the addition amount is 50 g / t of raw ore. The reverse flotation conditions are: air flow rate 1.5 m³ / t. 3 By selectively suppressing the flotation of inorganic impurities, low-ash refined carbon was obtained at a stirring speed of 2200 rpm and a stirring time of 5 min.

[0057] Example 2 This embodiment provides a flotation method for upgrading fine residues from high-grey aluminum electrolysis, specifically including the following steps: (1) The high-ash aluminum electrolytic fine residue was ball-milled and passed through a 200-mesh sieve to obtain ultrafine particles with a particle size of 200 mesh or less accounting for 75%; (2) Weigh 150g of ultrafine particle material and mix the ultrafine particle material with water to prepare a first slurry with a mass concentration of 30%; (3) The first slurry was pre-dispersed in an ultrasonic instrument, and 1.5% of the volume of the first slurry was added as a surfactant. The temperature was room temperature, the ultrasonic power was 250W, and the ultrasonic time was 10min to obtain the second slurry. (4) Add a composite collector and a frother to the second slurry for roughing flotation. The composite collector is added at a rate of 800 g / t of raw ore and is composed of diesel oil and butyl stearate in a mass ratio of 8:1. The frother is pine oil, and the addition rate is 66.6 g / t of raw ore. The roughing flotation conditions are: air flow rate 1.5 m³ / t. 3 Stirring speed 2200 rpm for 2 minutes to allow the composite collector to fully act, then add the foaming agent and continue stirring for 2 minutes to obtain rough carbon slurry and rough tailings. (5) Add water to the roughing carbon slurry to adjust the slurry concentration to 18% to obtain the third slurry; add a composite collector and a frother to the third slurry for fine flotation. The ratio of the composite collector and the type of the frother are the same as those of the roughing flotation. The amount of composite collector added is 300 g / t-raw ore, and the amount of frother added is 0 g / t-raw ore. The fine flotation conditions are: aeration flow rate 1 m³ / t. 3 The stirring speed is 2100 rpm and the stirring time is 4 min. The refined carbon slurry and refined tailings are obtained, and the refined tailings are returned to the roughing flotation process to realize the recycling of intermediate quality carbon slurry. (6) Add depressant to the selected carbon slurry for reverse flotation. The depressant is water glass, and the addition amount is 100 g / t raw ore. The reverse flotation conditions are: air flow rate 1.8 m³ / t. 3 By selectively suppressing the flotation of inorganic impurities, low-ash refined carbon was obtained at a stirring speed of 2200 rpm and a stirring time of 4 min.

[0058] Example 3 This embodiment provides a flotation method for upgrading fine residues from high-grey aluminum electrolysis, specifically including the following steps: (1) The high-ash aluminum electrolytic fine residue was ball-milled and passed through a 200-mesh sieve to obtain ultrafine particles with a particle size of 200 mesh or less accounting for 78%; (2) Weigh 175g of ultrafine particle material and mix the ultrafine particle material with water to prepare a first slurry with a mass concentration of 35%; (3) The first slurry was pre-dispersed in an ultrasonic instrument, and 2.5% of the volume of the first slurry was added as a surfactant. The temperature was room temperature, the ultrasonic power was 300W, and the ultrasonic time was 10min to obtain the second slurry. (4) Add a composite collector and a frother to the second slurry for roughing flotation. The composite collector is added at a rate of 1200 g / t of raw ore and is composed of methyl isobutyl methanol and octadecylsilane in a mass ratio of 6:1. The frother is methyl pentanol and is added at a rate of 66.6 g / t of raw ore. The roughing flotation conditions are: aeration flow rate of 1 m³ / t. 3 Stirring speed 2100 rpm for 3 minutes to allow the composite collector to fully act, then add the foaming agent and continue stirring for 3 minutes to obtain rough carbon slurry and rough tailings. (5) Add water to the roughing carbon slurry to adjust the slurry concentration to 15% to obtain the third slurry; add a composite collector and a frother to the third slurry for fine flotation. The ratio of the composite collector and the type of frother are the same as those for the roughing flotation, wherein the amount of composite collector added is 300 g / t-raw ore and the amount of frother added is 33.3 g / t-raw ore; the fine flotation conditions are: aeration flow rate 1.5 m 3 The stirring speed is 2300 rpm and the stirring time is 5 min. The refined carbon slurry and refined tailings are obtained, and the refined tailings are returned to the roughing flotation process to realize the recycling of intermediate quality carbon slurry. (6) Add depressant to the selected carbon slurry for reverse flotation. The depressant is water glass, and the addition amount is 150 g / t raw ore. The reverse flotation conditions are: aeration flow rate of 1.8 m³ / t. 3 By selectively suppressing the flotation of inorganic impurities, low-ash refined carbon was obtained at a stirring speed of 2200 rpm and a stirring time of 4 min.

[0059] Example 4 This embodiment provides a flotation method for upgrading fine residues from high-grey aluminum electrolysis, specifically including the following steps: (1) The high-ash aluminum electrolytic fine residue was ball-milled and passed through a 200-mesh sieve to obtain ultrafine particles with a particle size of 200 mesh or less accounting for 76%; (2) Weigh 125g of ultrafine particle material and mix the ultrafine particle material with water to prepare a first slurry with a mass concentration of 25%; (3) The first slurry was pre-dispersed in an ultrasonic instrument, and 2% of the volume of the first slurry was added as a surfactant. The temperature was room temperature, the ultrasonic power was 250W, and the ultrasonic time was 8min to obtain the second slurry. (4) Add a composite collector and a frother to the second slurry for roughing flotation. The composite collector is added at a rate of 1300 g / t of raw ore and is composed of kerosene and octadecylsilane in a mass ratio of 10:1. The frother is pine oil and is added at a rate of 66.6 g / t of raw ore. The roughing flotation conditions are: aeration flow rate of 2 m³ / t. 3 Stirring speed 2200 rpm for 4 minutes to allow the composite collector to fully act, then add frother and continue stirring for 4 minutes to obtain rough carbon slurry and rough tailings. (5) Add water to the roughing carbon slurry to adjust the slurry concentration to 18% to obtain the third slurry; add a composite collector and a frother to the third slurry for fine flotation. The ratio of the composite collector and the type of frother are the same as those for the roughing flotation, wherein the amount of composite collector added is 200 g / t-raw ore and the amount of frother added is 33.3 g / t-raw ore; the fine flotation conditions are: aeration flow rate 1.2 m 3 The stirring speed is 2200 rpm and the stirring time is 5 min. The refined carbon slurry and refined tailings are obtained, and the refined tailings are returned to the roughing flotation process to realize the recycling of intermediate quality carbon slurry. (6) Add depressant to the selected carbon slurry for reverse flotation. The depressant is water glass, and the addition amount is 200 g / t raw ore. The reverse flotation conditions are: air flow rate 2 m³ / t. 3 By selectively suppressing the flotation of inorganic impurities, low-ash refined carbon was obtained at a stirring speed of 2200 rpm and a stirring time of 4 min.

[0060] Example 5 This embodiment provides a flotation method for upgrading fine residues from high-grey aluminum electrolysis, specifically including the following steps: (1) The high-ash aluminum electrolytic fine residue was ball-milled and passed through a 200-mesh sieve to obtain ultrafine particles with a particle size of 200 mesh or less accounting for 80%; (2) Weigh 150g of ultrafine particle material and mix the ultrafine particle material with water to prepare a first slurry with a mass concentration of 30%; (3) The first slurry was pre-dispersed in an ultrasonic instrument, and 3% of the volume of the first slurry was added as a surfactant. The temperature was room temperature, the ultrasonic power was 300W, and the ultrasonic time was 10min to obtain the second slurry. (4) Add a composite collector and a frother to the second slurry for roughing flotation. The composite collector is added at a rate of 1200 g / t of raw ore and is made by mixing diesel oil and dodecylbenzene at a mass ratio of 6:1. The frother is pine oil and is added at a rate of 100 g / t of raw ore. The roughing flotation conditions are: air flow rate 2 m³ / t. 3Stirring speed 2200 rpm for 3 minutes to allow the composite collector to fully act, then add the foaming agent and continue stirring for 3 minutes to obtain rough carbon slurry and rough tailings. (5) Add water to the roughing carbon slurry to adjust the slurry concentration to 15% to obtain the third slurry; add a composite collector and a frother to the third slurry for fine flotation. The ratio of the composite collector and the type of frother are the same as those for the roughing flotation, wherein the amount of composite collector added is 300 g / t-raw ore and the amount of frother added is 33.3 g / t-raw ore; the fine flotation conditions are: aeration flow rate 1.2 m 3 The stirring speed is 2200 rpm and the stirring time is 5 min. The refined carbon slurry and refined tailings are obtained, and the refined tailings are returned to the roughing flotation process to realize the recycling of intermediate quality carbon slurry. (6) Add depressant to the selected carbon slurry for reverse flotation. The depressant is water glass, and the addition amount is 200 g / t raw ore. The reverse flotation conditions are: air flow rate 2 m³ / t. 3 By selectively suppressing the flotation of inorganic impurities, low-ash refined carbon was obtained at a stirring speed of 2200 rpm and a stirring time of 3 min.

[0061] Comparative Example 1 This comparative example is modified from the one disclosed in Example 4 as follows: The ball milling method is wet milling.

[0062] Comparative Example 2 This comparative example is modified from the one disclosed in Example 4 as follows: Ethanol was not added during the ultrasonic pre-dispersion process.

[0063] Comparative Example 3 This comparative example is modified from the one disclosed in Example 4 as follows: Kerosene was used as the collector instead of a composite collector made by combining hydrocarbon oil collectors and non-polar modifiers.

[0064] Comparative Example 4 This comparative example is modified from the one disclosed in Example 4 as follows: Only one roughing flotation was used, without subsequent fine flotation and reverse flotation.

[0065] Comparative Example 5 This comparative example is modified from the one disclosed in Example 4 as follows: The refined carbon after roughing and cleaning flotation was subjected to reverse flotation without the addition of inhibitors.

[0066] The composition of the high-ash aluminum electrolytic fine residue raw material is summarized in Table 1, and the flotation upgrading effect of the high-ash aluminum electrolytic fine residue is summarized in Table 2.

[0067] Table 1. Composition of fine residue raw materials from high-grey aluminum electrolysis

[0068] Table 2. Flotation effect on fine residues from high-grey aluminum electrolysis

[0069] It should be noted that grade refers to the percentage of fixed carbon in the refined carbon product, that is, the purity index of carbon in the final low-ash refined carbon. The higher the grade, the purer the refined carbon product. Recovery rate refers to the mass percentage of carbon in the raw material that ultimately enters the low-ash refined carbon product after the entire flotation process. The higher the recovery rate, the less carbon resources are lost.

[0070] As shown in Tables 1 and 2, the high-ash aluminum electrolytic fine residue flotation upgrading method provided in this application demonstrates significant advantages in both carbon upgrading and impurity removal. Regarding carbon upgrading, the grade of the low-ash refined carbon obtained in each embodiment is higher than 85%, with Examples 3 and 4 reaching 96% and 97.3% respectively, significantly higher than the comparative examples. In terms of recovery rate, Example 4 maintains a recovery rate of 57.8% while achieving a grade as high as 97.3%, achieving a good balance between grade and recovery rate. Regarding impurity element removal, all embodiments thoroughly remove fluorine and sodium. The fluorine content in the low-ash refined carbon obtained in Example 4 is reduced to 1.2%, and the sodium content to 0.27%, far lower than the fluorine content of 11.38% and the sodium content of 3.14% in the raw material, and also better than the impurity residue levels of all comparative examples.

[0071] Comparative Example 1 used wet grinding instead of dry grinding, and the grade of refined carbon obtained was only 87%, indicating that dry grinding plays an important role in maintaining the surface properties of materials and avoiding interference from fine mud.

[0072] Comparative Example 2, which did not undergo ultrasonic pre-dispersion treatment with ethanol, had a carbon content reduced to 83.1%, confirming that pre-dispersion treatment is indispensable for breaking up fine-particle mud-like agglomerates and enhancing surface differences.

[0073] Comparative Example 3 used kerosene as a single collector, with a refined carbon grade of 87.1%, demonstrating that the composite collector, which is a combination of hydrocarbon oil collector and non-polar modifier, can significantly improve the selective collection ability of fine carbon particles.

[0074] Comparative Example 4 only used one roughing flotation, and the refined carbon grade was only 86.7%, which shows that the setting of cleaning and reverse flotation is crucial for achieving deep purification.

[0075] Comparative Example 5, after selection, did not add inhibitors for reverse flotation, and the refined carbon grade was 91.6% with a high residual sodium fluoride, confirming that inhibitor-assisted reverse flotation is a necessary step to obtain low-ash, high-purity refined carbon.

[0076] Furthermore, one or more technical solutions in the embodiments of this application have at least the following technical effects or advantages: (1) By using surfactant combined with ultrasonic pre-dispersion treatment, this application can efficiently break the agglomeration of fine particles in high-ash aluminum electrolytic fine residue, clean and expose the fresh hydrophobic area on the carbon surface, significantly reduce the interference of fine mud on the flotation process, provide a clean and homogeneous surface environment for the selective action of subsequent reagents, and fundamentally strengthen the difference in floatability between carbon and impurities.

[0077] (2) The composite collector used in this application is composed of hydrocarbon oil collector and non-polar modifier. This combination not only enhances the collection ability of fine carbon particles, but also significantly improves the selectivity of the agent. It can effectively capture target carbon particles and reduce the entrainment of inorganic impurities in the roughing stage, thereby improving the grade and recovery efficiency of the roughing carbon slurry.

[0078] (3) This application achieves secondary deep purification of rough carbon slurry by setting up a low-concentration fine cleaning operation and combining it with a depressant reverse flotation process. The low-concentration environment reduces the viscosity of the slurry and reduces non-selective entrainment; the depressant selectively inhibits the flotation of residual inorganic impurities, which significantly improves the purity of the final low-ash refined carbon and achieves efficient quality improvement of carbonaceous materials.

[0079] (4) Using the method of this application, it is possible to obtain low-ash refined carbon with a refined carbon yield of more than 50% and a fixed carbon content of more than 97% from high-ash aluminum electrolytic fine residue with a fixed carbon content of less than 80%. At the same time, it effectively removes harmful impurities such as fluorine and sodium. The resulting product is of high quality and can be directly used as a high-quality carbon raw material for production, which significantly improves the utilization value of resources.

[0080] (5) The process flow design of this application is compact and stable. Purification is achieved only through physical and physicochemical methods. No strong corrosive chemical reagents such as acids and alkalis are used throughout the process. This not only avoids equipment corrosion problems, but also eliminates the burden of subsequent treatment of acid and alkali waste liquids, reducing environmental pressure and operating costs.

[0081] (6) The method of this application realizes the efficient resource utilization of bulk solid waste and high-ash aluminum electrolytic fine residue in the electrolytic aluminum industry, and transforms fine-grained waste that is difficult to reuse directly into high-value-added products, effectively alleviating the pressure of enterprise stockpiling and the problem of losses from external sales, and has significant economic benefits and promotion and application value.

[0082] 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 flotation method for improving the quality of fine residues from high-ash aluminum electrolysis, characterized in that, The method includes: High-gray aluminum electrolytic fine residues were ball-milled to obtain ultrafine particles. The ultrafine particles are mixed with water to form a slurry, thus obtaining the first slurry. A surfactant is added to the first slurry for pre-dispersion treatment to obtain a second slurry; A composite collector and a frother are added to the second slurry for roughing flotation to obtain roughing carbon slurry and roughing tailings. The coarse carbon slurry is adjusted to obtain a third slurry; The composite collector and the frother are added to the third slurry for fine flotation to obtain fine carbon slurry and fine tailings, and the fine tailings are returned to the roughing flotation process. An inhibitor is added to the selected carbon slurry to perform reverse flotation and obtain low-ash refined carbon; The composite collector is composed of a hydrocarbon oil collector and a non-polar modifier. The hydrocarbon oil collector includes at least one of kerosene, diesel oil, or methyl isobutyl methanol, and the non-polar modifier includes at least one of dodecylbenzene, octadecylsilane, or octadecyl alcohol. The foaming agent includes at least one of pine oil or methyl pentanol.

2. The method according to claim 1, characterized in that, The ball milling method is dry milling; The proportion of ultrafine particles with a particle size of 200 mesh or less is 75% to 80%. The mass concentration of the first slurry is 20% to 35%.

3. The method according to claim 1, characterized in that, The surfactant is ethanol, and the volume of the surfactant is 1% to 3% of the volume of the first slurry.

4. The method according to claim 1, characterized in that, The pre-dispersion treatment is ultrasonic dispersion, and the ultrasonic dispersion includes the following parameters: temperature is room temperature, ultrasonic power is 200W to 300W, and ultrasonic time is 5min to 10min.

5. The method according to claim 1, characterized in that, The mass ratio of the hydrocarbon oil collector to the nonpolar modifier is (5-10):

1.

6. The method according to claim 1, characterized in that, During the roughing flotation process, the amount of the composite collector added is 600 g / t raw ore to 1400 g / t raw ore, and the amount of the frother added is 0 g / t raw ore to 100 g / t raw ore. The roughing flotation includes the following parameters: air flow rate is 1 m³ / s. 3 / min~2m 3 The stirring speed is 1800 rpm to 2200 rpm, and the stirring time is 2 min to 4 min.

7. The method according to claim 1, characterized in that, During the flotation process, the amount of the composite collector added is 0 g / t raw ore to 400 g / t raw ore, and the amount of the frother added is 0 g / t raw ore to 100 g / t raw ore. The selective flotation includes the following parameters: air flow rate is 1 m³ / s. 3 / min~1.5m 3 The stirring speed is 2000 rpm to 2300 rpm, and the stirring time is 3 min to 5 min.

8. The method according to claim 1, characterized in that, The mass concentration of the third slurry is 15% to 20%.

9. The method according to claim 1, characterized in that, The inhibitor is water glass or tannin, and the amount of the inhibitor added is 50g / t-raw ore to 200g / t-raw ore.

10. The method according to claim 1, characterized in that, The reverse flotation includes the following parameters: air flow rate is 1 m³ / s. 3 / min~2m 3 The stirring speed is 2100 rpm to 2200 rpm, and the stirring time is 3 min to 5 min.

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