A process for the flotation of fluorite based on an oleic acid synergist

Abstract

The application relates to the technical field of fluorite processing, and discloses a fluorite flotation process based on an oleic acid synergist, which comprises the following steps: (1) adding sodium carbonate into a flotation receiving unit to adjust the pH of the ore slurry, and then sequentially adding oleic acid and the oleic acid synergist, and performing foaming through stirring and double-path air supply; the oleic acid synergist is obtained by mixing ethylene glycol and sorbitol, sequentially adding a fatty alcohol polyoxyethylene polyoxypropylene block ether, modified alkyl amphiprotic betaine and modified sodium polymaleate oligomer, and then standing and curing; and (2) after the foaming foam layer is stably formed, the foam is gathered through a foam scraping plate and collected into a concentrate receiving unit through negative pressure suction. The application has the comprehensive functions of rapid foaming, foam parameter standardization, fine mud dispersion and sinking suppression and wide temperature adaptation, and through the standardization of the physical parameters of the foam, the effective adaptation of the online visual monitoring and the automatic negative pressure foam scraping equipment is realized, so that the flotation process can be continuously operated in an unattended mode under closed-loop dynamic control.

Description

Technical Field

[0001] This invention relates to the field of mineral flotation chemical technology, and more specifically, to a fluorite flotation process based on oleic acid synergist. Background Technology

[0002] Fluorite, as an important industrial mineral raw material, has long been enriched by flotation using oleic acid as the main collector. The carboxyl groups of oleic acid can chemically adsorb calcium ions on the surface of fluorite to form a hydrophobic film, causing fluorite particles to adhere to bubbles and float with the foam layer, thereby achieving separation from gangue minerals.

[0003] Current industrial fluorite flotation typically uses a pure oleic acid system combined with sodium carbonate for slurry preparation. Foaming is achieved through a combination of mechanical stirring and aeration. The timing of foam removal is determined by manual observation or simple level sensing. A single additive (such as an alcohol-based foaming agent or a polymer inhibitor) is used to make limited adjustments to the foam stability or sludge behavior.

[0004] However, the pure oleic acid flotation system suffers from poor water solubility of oleic acid, easy solidification at low temperatures, and saponification and defoaming at high temperatures, leading to deterioration of flotation indicators with fluctuations in pulp temperature. Furthermore, the mixed size of oleic acid foam and the blurred bimodal grayscale histogram make automatic determination of foam mineralization maturity based on machine vision difficult, thus limiting the automation level of the flotation process. Foam toughness is also polarized; some foam breaks due to insufficient toughness, causing mineral loss, while others adhere and clog pipelines due to excessive toughness. Fine fluorite slime produced by ore crushing and classification easily agglomerates and settles at the bottom of the flotation cell, increasing reagent consumption and reducing fluorite recovery, and requiring frequent shutdowns for cleaning. Conventional single additives can only provide limited improvement in one aspect of emulsification dispersion or foam stability, failing to simultaneously meet the multiple requirements of wide temperature adaptability, standardized control of foam parameters, and dispersion and sedimentation of fine slime, and lacking compatibility with automated visual monitoring and foam scraping collection equipment. Therefore, these factors have a certain impact on the automation and stabilization of fluorite flotation. Summary of the Invention

[0005] The purpose of this invention is to provide a fluorite flotation process based on oleic acid synergist, which solves the technical problems in existing fluorite flotation processes, such as insufficient wetting and dispersibility of oleic acid collectors under low temperature or complex slurry conditions, poor foam stability, and difficulty in achieving both concentrate grade and recovery rate.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] This invention provides a fluorite flotation process based on oleic acid synergist, comprising the following steps:

[0008] (1) Sodium carbonate is added to the flotation receiving unit to adjust the pH of the pulp to 8.5-10.0, and then oleic acid and oleic acid synergist are added in sequence. Foaming is carried out by stirring and dual-channel air supply. The mass ratio of oleic acid to oleic acid synergist is 4:1-6:1. The oleic acid synergist is obtained by mixing ethylene glycol and sorbitol, adding fatty alcohol polyoxyethylene polyoxypropylene block ether, modified alkyl amphoteric betaine and modified sodium polymaleate oligomer in sequence, stirring evenly, and then sealing and allowing it to stand for aging.

[0009] (2) After the foam layer to be foamed is stably formed, the foam is collected by the foam scraper and then collected into the concentrate receiving unit by negative pressure.

[0010] As a further optimization of the above invention, in step (1), the mass fraction of each component in the oleic acid synergist is as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 30%-40%, modified alkyl amphoteric betaine 22%-27%, modified sodium maleate oligomer 26%-34%, and ethylene glycol and sorbitol compound polyol auxiliaries 12%-18%.

[0011] As a further optimization of the above invention, the fatty alcohol polyoxyethylene polyoxypropylene block ether has an EO addition number of 10-14 and a PO addition number of 6-10.

[0012] As a further optimization of the above invention, the modified alkyl amphoteric betaine is synthesized from C12-C14 fatty acids through a three-stage process of amidation, ethoxylation of mono-epoxy compounds, and quaternization of carboxymethyl compounds, with an active ingredient content of not less than 35% by mass fraction.

[0013] As a further optimization of the above invention, the modified sodium maleate oligomer is prepared by maleic anhydride-acrylic acid free radical oligomerization, hydrolysis and neutralization.

[0014] As a further optimization of the above invention, in step (1), the amount of sodium carbonate added relative to the mass of the slurry is 0.08%-0.15%, and the pH of the slurry is 9.0-9.5; the mass ratio of oleic acid to oleic acid synergist is 5:1.

[0015] As a further optimization of the above invention, the stirring and foaming time during the slurry preparation and foaming process is 3-8 minutes, the air supply pressure is 0.02-0.08 MPa, and the slurry temperature range is 0℃-50℃.

[0016] As a further optimization of the above invention, in step (2), the foam layer is imaged in real time by an image acquisition device installed on the top of the flotation receiving unit, and the foam layer thickness, single bubble equivalent diameter, foam layer development parameters and foam gray average value are extracted. When the foam layer thickness is 15-30cm, the single bubble equivalent diameter is 1.0-1.6mm, the foam layer development parameters are not less than 0.4 and the foam gray average value is 40-60, the foam scraping action is triggered.

[0017] As a further optimization of the above invention, when any one of the parameters such as foam layer thickness, equivalent diameter of a single bubble, foam layer development parameters, and average foam gray value is satisfied, the foam scraping and collection is paused and the stirring and foaming time is extended until all parameters meet the standards again, and then the foam scraping and collection is automatically restarted.

[0018] As a further optimization of the above invention, in step (2), the foam half-life is 100-130s and the foam breakage rate is ≤11%.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention utilizes an oleic acid synergist, where the EO and PO segments of fatty alcohol polyoxyethylene polyoxypropylene block ethers synergistically promote the rapid emulsification and dispersion of oleic acid in mineral slurry, forming mixed micelles. This shortens the foaming initiation time and overcomes the foaming lag of pure oleic acid systems. Modified alkyl amphoteric betaine adjusts the elasticity of the foam film and the drainage rate, resulting in a more uniform foam size distribution and concentrated grayscale values ​​within a quantifiable window range. This leads to a clear bimodal grayscale histogram in the foam image, providing quantifiable digital judgment for visual monitoring systems. The foundation is solid, overcoming the problem of the traditional oleic acid foam having a blurred bimodal grayscale peak that makes it impossible to automatically identify the timing of foam scraping; the modified sodium maleate oligomer disperses fine mineral mud through the dual effects of electrostatic repulsion and steric hindrance, and, in conjunction with the mechanical scraping of the rotating scraper at the bottom of the flotation receiving cell, effectively inhibits the accumulation and settling of mineral mud at the bottom of the cell, reducing reagent consumption and the frequency of cell shutdown for cleaning caused by sedimentation at the bottom of the cell; the low freezing point of ethylene glycol and the viscosity-retaining properties of sorbitol complement each other in the ethylene glycol and sorbitol compound polyol additive, enabling the quaternary composite oleic acid synergist system to maintain stable emulsification and foaming performance in a wide temperature range of 0 ℃-50 ℃, overcoming the defect of traditional oleic acid systems where flotation indicators fluctuate due to temperature changes.

[0021] This invention combines the functions of rapid foaming, standardized foam parameters, fine mud dispersion and sedimentation, and wide temperature adaptability, simplifying the reagent system. At the same time, the standardization of foam physical parameters enables effective adaptation to online visual monitoring and automatic negative pressure foam scraping equipment, allowing the flotation process to operate continuously in an unattended manner under closed-loop dynamic control, which is beneficial to improving the recovery rate of fluorite concentrate and reducing the intensity of manual intervention in flotation operation. Attached Figure Description

[0022] Figure 1 This is a schematic diagram comparing the foam performance of various embodiments and comparative examples provided in this invention;

[0023] Figure 2 This is a schematic diagram comparing the performance of fluorite flotation in various embodiments and comparative examples provided in this invention.

[0024] Figure 3 This refers to the foaming time under wide temperature conditions provided in the embodiments of the present invention;

[0025] Figure 4 This refers to the foam breakage rate under wide temperature conditions provided in the embodiments of the present invention;

[0026] Figure 5 This refers to the fluorite recovery rate under wide temperature conditions provided in the embodiments of the present invention. Detailed Implementation

[0027] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0028] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products, and all instruments used are conventional instruments known to those skilled in the art.

[0029] Before implementing this invention, the following equipment is required: a flotation receiving tank with dual stirring functions of bottom rotating scraper stirring and multi-layer horizontal stirring, wherein the bottom shaft and horizontal stirring rod are provided with air inlet channels to realize dual-path air supply for foaming, and the tank wall is provided with a slurry outlet connected to a screw discharge device; an image acquisition device is installed on the top of the flotation receiving tank for real-time image acquisition of the foam layer; a foam scraping and collecting device includes a lifting-driven horizontal foam scraper, a transfer pipe with adjustable rollers on the top of the tank, and a negative pressure pump to realize the mechanical collection and negative pressure suction of the foam.

[0030] This invention discloses a fluorite flotation process based on a wide-temperature-range quaternary composite oleic acid synergist. By compounding four components with synergistic functions in a specific ratio and combining them with a segmented flotation operation process, it achieves rapid emulsification and foaming of oleic acid in the pulp, standardized and controllable foam morphology parameters, continuous dispersion and suspension of fine sludge, and effective adaptation of the flotation process with automated monitoring and foam scraping equipment. The process includes the following steps:

[0031] S1. Preparation of a quaternary composite oleic acid synergist

[0032] Step 1.1: Add ethylene glycol (analytical grade, purity ≥99.0%) and sorbitol (solid content ≥70% aqueous solution) into a stirred tank at a mass ratio of 1:1, and stir at 200-300 r / min for 10 min at 20-30℃ to ensure that the two are fully miscible and obtain a homogeneous polyol base solution.

[0033] Step 1.2: Add fatty alcohol polyoxyethylene polyoxypropylene block ether to the polyol base liquid, increase the stirring speed to 400 r / min and continue stirring for 15 min to make the fatty alcohol polyoxyethylene polyoxypropylene block ether uniformly dispersed in the polyol base liquid, and obtain the block ether dispersion.

[0034] Step 1.3: Add the modified alkyl amphoteric betaine to the block ether dispersion by dropwise, and maintain stirring at 400 r / min for 20 min to allow the modified alkyl amphoteric betaine and fatty alcohol polyoxyethylene polyoxypropylene block ether to be fully compounded and emulsified in the polyol-based liquid medium to obtain a ternary mixture.

[0035] Step 1.4: Add modified sodium maleate oligomer to the ternary mixture and continue stirring at 400 r / min for 30 min to form a homogeneous dispersion system, thus obtaining a quaternary mixture.

[0036] Step 1.5: The quaternary mixture is sealed and allowed to stand for 2-4 hours to fully establish the mixed micelle structure between fatty alcohol polyoxyethylene polyoxypropylene block ether and modified alkyl amphoteric betaine, and to stabilize the dispersion state of modified sodium maleate oligomer in the system. After aging, a light yellow transparent liquid quaternary composite oleic acid synergist is obtained.

[0037] In particular, the stirring operations in steps 1.1-1.4 above are all carried out under normal pressure; the sealed static curing temperature in step 1.5 is 20-30℃, which is consistent with the mixing temperature in step 1.1, so as to avoid temperature fluctuations from interfering with the micelle structure establishment process.

[0038] All preparation operations in steps 1.1-1.5 above are carried out under normal atmospheric pressure without the need for inert gas protection. The materials in the stirred tank in each step are handled in an open or closed manner under normal atmospheric pressure. During the closed standing period in step 1.5, the pressure inside the tank is balanced with the external atmospheric pressure, and no pressurization or depressurization operations are involved.

[0039] In step 1.1 above, ethylene glycol has low toxicity and is irritating. Operators should wear chemical-resistant gloves and goggles during weighing and feeding. The operation should be carried out in a well-ventilated environment to avoid direct skin contact and inhalation of vapors.

[0040] After the aging process in step 1.5 above, the quality of the quaternary composite oleic acid synergist product can be confirmed by visual observation (transparency, color uniformity) and viscosity measurement. The kinematic viscosity of the quaternary composite oleic acid synergist product at 25℃ is 80-150 mm² / s, and the transparency is judged as having no obvious layering or turbidity when viewed visually. The quaternary composite oleic acid synergist product should be stored in a sealed container at a temperature of 0-50℃ for a period not exceeding 6 months. Before use, it must be visually confirmed that there is no sedimentation or layering before it can be put into use.

[0041] The mass fractions of each component in the quaternary composite oleic acid synergist are as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 30%-40%, modified alkyl amphoteric betaine 22%-27%, modified sodium maleate oligomer 26%-34%, and ethylene glycol and sorbitol compound polyol auxiliaries 12%-18%.

[0042] This fatty alcohol polyoxyethylene polyoxypropylene block ether is a nonionic block ether obtained by sequentially adding an ethylene oxide (EO) segment and a propylene oxide (PO) segment to a C12-C16 fatty alcohol as an initiator. The EO segment has a degree of polymerization of 10-14, the PO segment has a degree of polymerization of 6-10, the hydrophilic-lipophilic balance value is 12-15, the kinematic viscosity at 25°C is 50-120 mm² / s, and the cloud point (based on a 1% aqueous solution) is 60-75°C. The EO segment provides hydrophilicity to promote the emulsification and dispersion of oleic acid in the slurry, while the PO segment provides lipophilicity to form stable mixed micelles with oleic acid. The synergistic effect of the EO and PO segments enables oleic acid to maintain effective emulsification and foaming ability over a wide temperature range. Preferably, the EO segment has a degree of polymerization of 12, the PO segment has a degree of polymerization of 8, and the corresponding hydrophilic-lipophilic balance value is 13-14.

[0043] This modified alkyl amphoteric betaine was prepared by adding 1.0 mol of a C12-C14 mixed coconut oil acid (65% C12, 35% C14) to a reaction vessel and melting it at 110°C. N,N-dimethyl-1,3-propanediamine (1.1 mol) was added dropwise over 2 hours with stirring at 300 rpm. The temperature was then raised to 140-150°C and maintained for 6 hours for continuous dehydration until the free acid concentration was ≤0.3 mg / g. The mixture was then cooled to 80°C and filtered to obtain a pale yellow amamidopropyl dimethylamine intermediate. The intermediate was transferred to a pressure vessel, and isopropanol (12% of the total mass) was added. The mixture was then purged with nitrogen. Three times, ethylene oxide (1.05 mol) was uniformly introduced at 120℃ and 0.12-0.15 MPa for 3 h, followed by aging at this temperature for 2 h. Neutralization with a small amount of NaOH at 70℃ yielded an ethoxylated modified tertiary amine. The modified tertiary amine was then mixed with water and isopropanol, followed by the addition of sodium chloroacetate (1.08 mol). The system pH was maintained at 7.2-7.8 with 30% NaOH, and the mixture was kept at 85℃ for 5.5 h, with the endpoint being ≤0.1% free tertiary amine. NaCl was removed by filtration at 40℃, isopropanol was removed under reduced pressure, water was added to adjust the active ingredient to ≥35 wt%, and the mixture was aged at room temperature for 2 h to obtain a light yellow modified alkyl amphoteric betaine. The modified alkyl amphoteric betaine arranged as zwitterions at the gas-liquid interface in the foam liquid film. Through intermolecular electrostatic and hydrogen bonding interactions, it regulates the elasticity of the liquid film and the drainage rate, resulting in more uniform foam size and a concentrated gray distribution, which is beneficial for the standardization of foam morphology parameters.

[0044] The modified sodium maleate oligomer comprises, by weight, 100 parts of maleic anhydride monomer, 12 parts of acrylic acid modified monomer, 6.5 parts of ammonium persulfate initiator, 4.8 parts of mercaptoethanol chain transfer agent, 32% sodium hydroxide, and deionized water (to bring the total concentration of the system to 40 wt%). Add 60% total deionized water to an atmospheric pressure reactor and heat to 85℃ for later use. Prepare monomer mixture (maleic anhydride + acrylic acid + remaining deionized water) and initiator aqueous solution (ammonium persulfate dissolved in a small amount of water). At a constant temperature of 85℃, add the monomer solution and initiator solution dropwise simultaneously for 3 hours. After the addition is complete, add all mercaptoethanol and maintain the temperature at 90℃ for 3 hours to complete the oligomerization reaction. Use chain transfer agent to precisely control the polymer molecular weight range of 3000-5000. Cool down to 60℃ and slowly add 32% sodium hydroxide solution while stirring throughout the process. Adjust the final pH of the system to 7.0-7.5 to completely hydrolyze the molecular chain anhydride into sodium carboxylate groups, obtaining a polymaleic acid oligomer solution. Remove trace amounts of unreacted monomers under reduced pressure and allow to stand at room temperature for 3 hours. Filter to remove trace amounts of insoluble impurities, obtaining a transparent liquid modified sodium maleate oligomer with an active ingredient content of 40 wt% and a viscosity of 20-60 mPa·s at 25℃. The sodium carboxylate groups on the modified sodium maleate oligomer molecular chain dissociate in the slurry and generate electrostatic repulsion on the surface of fine fluorite slime particles. At the same time, the adsorption of oligomer segments on the surface of slime particles provides a steric hindrance effect. The superposition of electrostatic repulsion and steric hindrance effectively inhibits the agglomeration and settling of fine fluorite slime at the bottom of the flotation cell.

[0045] It should be noted that the maleic anhydride used in the synthesis of the above-mentioned modified sodium maleate oligomers is an irritating organic acid anhydride. Weighing and feeding operations should be carried out in a fume hood, and operators should wear protective gloves and goggles to avoid dust inhalation and skin contact. Acrylic acid has a corrosive and irritating odor, and should be handled in a ventilated environment while wearing acid-resistant gloves. Sodium hydroxide is a strong alkaline substance, and alkali-resistant gloves and face protection should be worn during preparation and use to avoid splashing into the skin and eyes.

[0046] In the polyol additive, the mass ratio of ethylene glycol to sorbitol is 1:1, with ethylene glycol having a purity ≥99.0% and sorbitol used in the form of an aqueous solution with a solid content ≥70%. The low freezing point of ethylene glycol (Tf = -12.9 ℃, where Tf is the freezing point temperature of ethylene glycol) combined with the high viscosity and water-retention properties of sorbitol prevents the solidification and crystallization of the quaternary composite oleic acid synergist system at low temperatures and maintains the system viscosity at high temperatures, thereby inhibiting defoaming caused by excessive migration of surfactant molecules from the liquid film. This allows the quaternary composite oleic acid synergist to maintain effective emulsification and foaming functions within a slurry temperature range of 0 ℃ to 50 ℃.

[0047] S2, Slurry preparation, foaming and tailings discharge

[0048] Step 2.1: The crushed and graded fluorite ore is fed into the flotation receiving tank in the form of slurry. Sodium carbonate (industrial grade, purity ≥98%), oleic acid (industrial grade, acid value ≥195mgKOH / g), and the above-mentioned quaternary composite oleic acid synergist are added to the tank in sequence. The amount of sodium carbonate added relative to the slurry mass is 0.05%-0.20% (mass ratio) to adjust the pH of the slurry to an alkaline environment of 8.5-10.0, thereby activating the collecting performance of oleic acid. The mass ratio of oleic acid to quaternary composite oleic acid synergist is 4:1-6:1.

[0049] In step 2.1, sodium carbonate powder is prone to generating alkaline dust during the feeding process. Operators should wear dust masks and goggles and operate in a well-ventilated environment when feeding. Oleic acid may generate oil mist during stirring. The operating area should be kept well-ventilated.

[0050] It should be noted that the order of adding sodium carbonate, oleic acid, and the quaternary compound oleic acid synergist in step 2.1 is as follows: first add sodium carbonate and stir until the pH of the slurry stabilizes and reaches the target range, then add oleic acid, and finally add the quaternary compound oleic acid synergist; sodium carbonate is added directly to the slurry in solid powder form, while oleic acid and the quaternary compound oleic acid synergist are added slowly in liquid form under stirring conditions. The addition of all three agents is carried out at room temperature and pressure without the need for cooling or heating assistance; when adding oleic acid and the quaternary compound oleic acid synergist, the stirring paddle in the tank is continuously running to ensure that the agents are in full contact with the slurry.

[0051] It should also be noted that after sodium carbonate is added in step 2.1, oleic acid can only be added after the pH value of the slurry has stabilized within the target range. This is to ensure that sodium carbonate is fully dissolved and reacts with calcium and magnesium ions in the slurry to complete the precipitation reaction, thus avoiding the formation of calcium or magnesium soap precipitates by the subsequent addition of oleic acid with free calcium and magnesium ions, which would consume the effective collector. The pH value can be detected online with a glass electrode or offline by sampling, with a detection interval of no more than 2 minutes. The criterion for judging pH stability is that the difference between two consecutive detection values ​​does not exceed 0.1.

[0052] Step 2.2: After the reagent addition is completed and the pH of the slurry is confirmed to be within the target range, the bottom rotary scraper agitation and multi-layer horizontal agitation of the flotation receiving cell are started simultaneously. At the same time, the bottom shaft air inlet channel and the horizontal agitator air inlet channel are opened for dual-path air supply. Under the synergistic effect of mechanical agitation and air blowing, oleic acid is rapidly dispersed in the slurry with the emulsification assistance of the quaternary composite oleic acid synergist and a foam layer is formed at the gas-liquid interface. During the agitation and air supply process, the bottom rotary scraper mechanically scrapes the settled sludge at the bottom of the cell and rolls it back into the slurry suspension area. Combined with the electrostatic repulsion and steric hindrance effect provided by the modified sodium maleate oligomer in the quaternary composite oleic acid synergist, the dual sedimentation suppression effect of chemical dispersion and mechanical disturbance is achieved.

[0053] In step 2.2 above, the duration of stirring and foaming is 3-8 minutes, with foam maturation in a minimum of 3 minutes and the formation of a foam layer in a maximum of 8 minutes; the applicable temperature range for the slurry is 0℃-50℃, and no adjustment of stirring parameters or reagent dosage is required within this temperature range; the air supply pressure is 0.02-0.08MPa to ensure that the bubbles are evenly distributed in the slurry without generating excessive large bubbles; the air supply gas is compressed and filtered air, which is simultaneously introduced through two channels: the air inlet channel at the bottom of the tank shaft and the air inlet channel of the horizontal stirring rod.

[0054] Step 2.3: While stirring and foaming continue, the lower tailings are continuously discharged through the tank wall outlet via the screw discharge device, maintaining the stability of the liquid level in the flotation cell and the continuous renewal of the slurry.

[0055] Within the alkaline range of pH 8.5-10.0, the carboxyl groups in oleic acid molecules fully dissociate into carboxylate ions, which can form stable chemical adsorption with calcium ions on the surface of fluorite. At the same time, the alkaline environment is conducive to the emulsifying function of fatty alcohol polyoxyethylene polyoxypropylene block ether in the quaternary composite oleic acid synergist.

[0056] S3, Foam Scraping and Collection

[0057] Step 3.1: After a continuous and stable foam layer is formed above the liquid surface in the flotation receiving tank, the horizontal foam scraper is adjusted to the height range of the foam layer by the lifting drive. The working height range is 15-30cm (measured by the distance from the bottom of the foam layer to the top edge of the tank).

[0058] Step 3.2: Start the horizontal drive to make the foam scraper move horizontally at a uniform speed (moving speed is 5-15cm / s), continuously gathering the foam to the transfer port on one side of the tank; adjust the depth of the transfer tube insertion by the roller at the top of the tank to match the actual foam thickness.

[0059] Step 3.3: Turn on the negative pressure pump to create an adsorption force at the transfer port, and completely extract the collected foam through the transfer tube and collect it into the concentrate receiving container to obtain a foam product containing fluorite minerals. After subsequent routine defoaming, dehydration and drying, fluorite concentrate can be obtained.

[0060] Furthermore, the above-mentioned quaternary composite oleic acid synergist formulation enables the foam to possess the following physical properties to adapt to mechanical foam scraping and negative pressure collection operations: the foam half-life is 100-130s (the foam half-life is characterized by the time required for the foam layer height to drop to 50% of the initial height under static conditions); the foam maintains a low breakage rate under scraper shearing and negative pressure suction conditions, with a foam scraping breakage rate ≤11%; the foam does not exhibit obvious wall adhesion and clumping after standing for 1 minute, and does not block the foam scraping transfer port and collection pipe.

[0061] Based on steps S2 and S3, the following steps are also included to achieve online quantitative determination of foam mineralization maturity, replacing manual visual observation and providing precise triggering conditions for foam scraping operations:

[0062] S4. Online visual monitoring of foam and quantitative determination of foam scraping conditions

[0063] During the stirring and foaming process in step 2.2, an image acquisition device installed at the top of the flotation receiving tank is used to acquire real-time images of the foam layer. The image acquisition frame rate is 2 frames / s, and the following parameters are extracted and determined sequentially from the acquired images:

[0064] Step 4.1: Extract basic morphological parameters of foam from the acquired images and determine whether the following conditions are met simultaneously: the foam layer thickness is 15-30cm and the interface between the foam and the slurry is flat without any unevenness or collapse; the equivalent diameter of a single bubble is in the range of 1.0-1.6mm, and there are no large bubbles with an equivalent diameter greater than 3mm or micro-fragments with an equivalent diameter less than 0.3mm in the image; the foam color is uniformly light grayish-white, and there are no transparent voids or black mud bubbles.

[0065] Step 4.2: Perform grayscale analysis on the acquired images, extract the following quantization parameters, and determine whether they meet the standards: the grayscale value of the foam layer is distributed in the range of 0-80, the grayscale value of the slurry layer is distributed in the range of 200-255, the grayscale histogram shows a clear bimodal distribution, and the trough between the two peaks corresponds to a unique and stable boundary threshold; calculate the foam layer development parameter deR and determine whether it meets the requirement of deR≥0.4; extract the mean grayscale value of the foam, grayF, and determine whether it is stable in the range of 40-60, where grayF is the arithmetic mean of the grayscale values ​​of all pixels in the foam region; extract the foam texture feature parameter foR and determine whether it is located in the range of 0.12-0.22.

[0066] Step 4.3: Based on all parameters extracted in Steps 4.1 and 4.2, calculate the comprehensive state parameter Rat. When Rat ≤ RP and all parameters in Steps 4.1 and 4.2 simultaneously meet the above standard range, the foam mineralization degree is determined to be up to standard, where RP is the preset upper limit threshold for triggering foam scraping. After reaching the standard, extract the minimum working height value corresponding to the current foam layer and output it to the foam scraping collection device in Step 3 to trigger the foam scraping collection process from Step 3.1 to Step 3.3. If any parameter in Steps 4.1 and 4.2 does not meet the standard range, extend the stirring and foaming time in Step 2.2 by 2-5 minutes each time, and continue to collect and monitor until all parameter indicators simultaneously meet the standard.

[0067] Based on steps S2, S3, and S4, the following steps are also included to achieve closed-loop dynamic control of the entire flotation process, enabling the three stages of pulp conditioning and foaming, visual monitoring, and foam scraping and collection to operate continuously and autonomously:

[0068] S5, Full-process closed-loop dynamic control

[0069] The slurry preparation and foaming operation in step S2, the visual monitoring and judgment in step S4, and the foam scraping and collection operation in step S3 are carried out synchronously and continuously. The image acquisition device refreshes the numerical parameters of foam layer thickness, gray scale distribution, and mineralization maturity in real time. When any of the following conditions are detected: foam layer thickness is less than 15cm, deR < 0.4, or Rat > RP, the foam scraping operation in step 3 is automatically paused and the stirring and foaming time in step 2.2 is extended to replenish the amount of foam and improve the degree of mineralization. When all foam parameters meet the standards again, the foam scraping and collection in step 3 is automatically restarted, realizing unattended automatic separation throughout the flotation process.

[0070] To further illustrate the technical solution of the present invention, specific embodiments and comparative examples are provided below to describe the present invention.

[0071] Fluorite ore was crushed and graded to a particle size of at least 70% to 74μm, with fine slime (particle size <10μm) accounting for 8%-12% of the total ore mass. A slurry was prepared using pure water at a solid-liquid mass ratio of 30%, with each batch of slurry weighing 10kg. Slurries from the same batch were obtained from the same ore sample to ensure consistent ore quality across experiments. The fluorite grade (calculated as CaF2 mass fraction) in the ore was 55%-60%. For each example and comparative example, a separate batch of slurry was prepared, with the CaF2 grade deviation between batches not exceeding 1% to ensure comparability between experiments.

[0072] The effective volume of the flotation receiving cell is 8m³. 3 The rotating scraper at the bottom of the tank rotates at 60 r / min, and the multi-layer horizontal stirring rotates at 120 r / min. The image acquisition device is an industrial area array camera with a resolution of 1280×960 pixels, a grayscale bit depth of 8 bits, and a lens field of view covering the entire area of ​​the top froth layer of the flotation receiving cell. The negative pressure pump has a rated flow rate of 5 L / min. The slurry temperature is maintained at 25±1℃.

[0073] The oleic acid used in this invention is saponified oleic acid.

[0074] Example 1

[0075] In this embodiment, the mass fractions of each component in the oleic acid synergist are as follows: 32% fatty alcohol polyoxyethylene polyoxypropylene block ether, 25% modified alkyl amphoteric betaine, 31% modified sodium maleate oligomer, and 12% ethylene glycol and sorbitol compound polyol auxiliaries.

[0076] Ethylene glycol and sorbitol aqueous solution were added to a stirred tank at a mass ratio of 1:1 and stirred at 20℃ and 200 r / min for 10 min to obtain a homogeneous polyol base liquid. Fatty alcohol polyoxyethylene polyoxypropylene block ether (EO segment degree of polymerization 10, PO segment degree of polymerization 6, HLB value 12, kinematic viscosity at 25℃ 50 mm² / s, 1% aqueous solution cloud point 60℃) was added, and the stirring speed was increased to 400 r / min for 15 min. Modified alkyl amphoteric betaine (active content ≥35%, 10% aqueous solution pH=5.0) was added dropwise, and the mixture was stirred at 400 r / min for 20 min. Modified sodium maleate oligomer (weight average molecular weight 3000, viscosity at 25℃ 20 mPa·s) was added, and the mixture was stirred at 400 r / min for 30 min. The mixture was then allowed to stand and mature in a sealed container at 20℃ for 2 h and stored at 10℃. The resulting quaternary composite oleic acid synergist product had a kinematic viscosity of 80 mm² / s at 25℃ and showed no visible stratification.

[0077] Add fluorite slurry to the flotation receiving cell, then add sodium carbonate (0.05% of the slurry mass) to adjust the slurry pH to 8.5. Next, add oleic acid and a quaternary composite oleic acid synergist at a mass ratio of 4:1. Start dual-path stirring and dual-path air supply at a pressure of 0.02 MPa, and continue stirring and foaming for 5 minutes until the foam layer stabilizes. Adjust the foam scraper to an operating height of 15 cm and collect the foam at a lateral movement speed of 5 cm / s. Use a negative pressure pump at -0.02 MPa to pump the foam into the concentrate receiving container. In step 4, the image acquisition frame rate is set to 2 frames / s. The foam mineralization maturity criteria are: foam layer thickness ≥ 8 cm, single bubble equivalent diameter between 1.0 and 1.6 mm, grayF = 40, foR = 0.12; the resulting foam half-life is 10³ s.

[0078] Example 2

[0079] In this embodiment, the mass fractions of each component in the oleic acid synergist are as follows: 32% fatty alcohol polyoxyethylene polyoxypropylene block ether, 25% modified alkyl amphoteric betaine, 28% modified sodium maleate oligomer, and 15% ethylene glycol and sorbitol compound polyol auxiliaries. The procedures are the same as in Example 1. After being sealed and allowed to stand for 3 hours at 25°C and stored at 22°C, the resulting quaternary composite oleic acid synergist product has a kinematic viscosity of 115 mm² / s at 25°C and shows no visible stratification.

[0080] Sodium carbonate was added at 0.05% of the slurry mass, the slurry pH was adjusted to 8.5, the mass ratio of oleic acid to quaternary oleic acid synergist was 4:1, the air supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 10 cm / s, and the negative pressure pump operated at a negative pressure of -0.04 MPa. In step 4, the image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=50, foR=0.17, and the obtained foam half-life was 106 s.

[0081] Example 3

[0082] In this embodiment, the mass fractions of each component in the oleic acid synergist are as follows: 35% fatty alcohol polyoxyethylene polyoxypropylene block ether, 27% modified alkyl amphoteric betaine, 26% modified sodium maleate oligomer, and 12% ethylene glycol and sorbitol compound polyol auxiliaries. The operation steps are the same as in Example 1. The resulting quaternary composite oleic acid synergist has a kinematic viscosity of 150 mm² / s at 25°C and shows no visible stratification.

[0083] Sodium carbonate was added at 0.05% of the slurry mass, the slurry pH was adjusted to 8.5, the mass ratio of oleic acid to quaternary oleic acid synergist was 4:1, the air supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 15 cm / s, and the negative pressure pump operated at a negative pressure of -0.06 MPa. In step 4, the image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=45, foR=0.15, and the obtained foam half-life was 112 s.

[0084] Example 4

[0085] In this embodiment, the preparation of the oleic acid synergist was the same as in Example 2. The amount of sodium carbonate added was 0.08% of the slurry mass, the pH of the slurry was adjusted to 9.0, and the mass ratio of oleic acid to the quaternary composite oleic acid synergist was 4:1. The gas supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 10 cm / s, and the negative pressure pump operated at a negative pressure of -0.04 MPa. The image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=55, foR=0.17, and the half-life of the obtained foam was 115 s.

[0086] Example 5

[0087] In this embodiment, the preparation of the oleic acid synergist was the same as in Example 2. The amount of sodium carbonate added was 0.12% of the slurry mass, the pH of the slurry was adjusted to 9.25, and the mass ratio of oleic acid to the quaternary composite oleic acid synergist was 4:1. The gas supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 10 cm / s, and the negative pressure pump operated at a negative pressure of -0.04 MPa. The image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=55, foR=0.17, and the half-life of the obtained foam was 117 s.

[0088] Example 6

[0089] In this embodiment, the preparation of the oleic acid synergist was the same as in Example 2. The amount of sodium carbonate added was 0.15% of the slurry mass, the pH of the slurry was adjusted to 9.5, and the mass ratio of oleic acid to the quaternary composite oleic acid synergist was 4:1. The gas supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 10 cm / s, and the negative pressure pump operated at a negative pressure of -0.04 MPa. The image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=55, foR=0.17, and the half-life of the obtained foam was 118 s.

[0090] Example 7

[0091] In this embodiment, the preparation of the oleic acid synergist is the same as in Example 2. The amount of sodium carbonate added is 0.20% of the slurry mass, the pH of the slurry is adjusted to 10, and the mass ratio of oleic acid to the quaternary composite oleic acid synergist is 4:1. The gas supply pressure is 0.05 MPa, and the stirring and foaming lasts for 5 minutes. The working height of the foam scraper is 15 cm, the lateral movement speed is 10 cm / s, and the negative pressure pump operates at a negative pressure of -0.04 MPa. The image acquisition frame rate is 2 frames / s, the maturity judgment parameters are: grayF=55, foR=0.17, and the half-life of the obtained foam is 115 s.

[0092] Example 8

[0093] In this embodiment, the preparation of the oleic acid synergist was the same as in Example 2. The amount of sodium carbonate added was 0.15% of the slurry mass, the pH of the slurry was adjusted to 9.5, and the mass ratio of oleic acid to the quaternary composite oleic acid synergist was 5:1. The gas supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 10 cm / s, and the negative pressure pump operated at a negative pressure of -0.04 MPa. The image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=60, foR=0.22, and the half-life of the obtained foam was 128 s.

[0094] Example 9

[0095] In this embodiment, the preparation of the oleic acid synergist was the same as in Example 2. The amount of sodium carbonate added was 0.15% of the slurry mass, the pH of the slurry was adjusted to 9.5, and the mass ratio of oleic acid to the quaternary composite oleic acid synergist was 6:1. The gas supply pressure was 0.05 MPa, and the stirring and foaming lasted for 5 minutes. The working height of the foam scraper was 15 cm, the lateral movement speed was 10 cm / s, and the negative pressure pump operated at a negative pressure of -0.04 MPa. The image acquisition frame rate was 2 frames / s, the maturity judgment parameters were: grayF=55, foR=0.18, and the half-life of the obtained foam was 122 s.

[0096] Comparative Example 1

[0097] Without adding the quaternary compound oleic acid synergist, only oleic acid is used as the collector. The amount of oleic acid is the same as the total amount of oleic acid and quaternary compound oleic acid synergist added in Example 8 (that is, under the premise that the total amount of oleic acid and synergist remains unchanged in Example 2, the proportion of synergist is completely replaced with an equal mass of oleic acid). The amount of sodium carbonate added is 0.15%, the pH of the slurry is 9.5, and the other process parameters (air supply pressure, stirring time, and foaming parameters) are the same as in Example 8. The slurry temperature is room temperature (25°C).

[0098] Comparative Example 2

[0099] In this comparative example, the mass fractions of each component in the oleic acid synergist are as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 44.5%, modified alkyl amphoteric betaine 34.7%, and ethylene glycol and sorbitol compound polyol auxiliaries 20.8%. The preparation steps are the same as in Example 2, and the resulting synergist does not contain modified sodium maleate oligomers. The flotation process parameters are the same as in Example 8.

[0100] Comparative Example 3

[0101] In this comparative example, the mass fractions of each component in the oleic acid synergist are as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 37.6%, modified alkyl amphoteric betaine 29.5%, and modified sodium maleate oligomer 32.9%. The preparation steps are the same as in Example 2. The resulting synergist does not contain ethylene glycol and sorbitol compound polyol additives. The flotation process parameters are the same as in Example 8.

[0102] Comparative Example 4

[0103] In this comparative example, the mass fractions of each component in the oleic acid synergist are as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 44.3%, modified sodium maleate oligomer 35.1%, and ethylene glycol and sorbitol compound polyol auxiliaries 20.6%. The preparation steps are the same as in Example 2, and the resulting synergist does not contain modified alkyl amphoteric betaine. The flotation process parameters are the same as in Example 8.

[0104] Comparative Example 5

[0105] In this comparative example, the oleic acid synergist contains only 100% fatty alcohol polyoxyethylene polyoxypropylene block ether. The flotation process parameters are the same as in Example 8.

[0106] Comparative Example 6

[0107] In this comparative example, the mass fractions of each component in the oleic acid synergist are as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 32%, modified alkyl amphoteric betaine 25%, sodium maleate oligomer 28%, and ethylene glycol and sorbitol compound polyol auxiliaries 15%. The preparation steps are the same as in Example 2. The flotation process parameters are the same as in Example 8.

[0108] The preparation process of polysodium maleate oligomer is as follows: water is pre-added to the reactor and the temperature is raised to 85°C. Simultaneously, maleic anhydride aqueous solution and ammonium persulfate initiator solution (100 parts maleic anhydride and 5 parts ammonium persulfate) are added dropwise over 2.5 hours. After the addition is completed, the mixture is aged at 90°C for 2 hours, then cooled to 60°C. The mixture is neutralized to pH 7.5 with 32% liquid alkali to allow the anhydride to open its ring and generate sodium carboxylate. Trace impurities are filtered out, and a 40wt% aqueous solution is prepared as the finished product.

[0109] Comparative Example 7

[0110] In this comparative example, the mass fractions of each component in the oleic acid synergist are as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 32%, alkyl betaine 25%, modified sodium maleate oligomer 28%, and ethylene glycol and sorbitol compound polyol auxiliaries 15%. The preparation steps are the same as in Example 2. The flotation process parameters are the same as in Example 8.

[0111] The preparation process of alkyl betaine is as follows: C12-C14 mixed coconut oil acid and N,N-dimethyl-1,3-propanediamine are mixed at a molar ratio of 1:1.05, kept at 140℃ for 5 hours for dehydration, and after the free acid is ≤0.5mg / g, it is cooled and filtered to obtain an unmodified tertiary amine intermediate. Sodium chloroacetate is dissolved in water with 30% NaOH, pH 8.0, and kept at 80℃ for 4.5 hours. Sodium chloride is removed by filtration, water is added to adjust the active product to 30wt%, and the mixture is allowed to stand before being discharged.

[0112] All embodiments and comparative examples were performed according to the following unified process:

[0113] Add 10 kg of slurry to the flotation receiving tank. Add sodium carbonate powder directly to the slurry according to the amount specified in each embodiment or comparative example. Start dual-path stirring. Wait until the difference between two consecutive pH readings of the slurry measured by the glass electrode does not exceed 0.1. Under stirring conditions, slowly add oleic acid and quaternary composite oleic acid synergist (or the alternative reagent specified in the comparative example) in sequence. Record the time from the start of oleic acid addition to when the foam layer thickness stabilizes at 15 cm as detected by the image acquisition device (excluding the brief period when the foam height reaches 15 cm due to violent foaming at the beginning) as the foaming start time t. foam ;

[0114] Start dual gas supply according to the gas supply pressure specified in each embodiment or comparative example, and continuously stir and foam until the specified time; Step 4: The visual monitoring module collects foam images in real time, extracts grayF, foR, deR and foam layer thickness, and records the time when all parameters meet the maturity judgment criteria.

[0115] Step 3 is triggered to collect the foam. The foam is collected into the concentrate receiving container according to the foam collection parameters specified in each embodiment or comparative example. After collection, the concentrate is subjected to routine defoaming, filtration and dehydration, and drying at 105°C for 2 hours. The dry mass of the concentrate is then weighed.

[0116] The mass fraction of CaF2 in the concentrate was determined by X-ray fluorescence spectroscopy, and the particle size distribution (d) of the concentrate was determined by laser particle size analyzer. 50 The fluorite recovery rate R is calculated by combining the quality and grade of the raw ore input. rec The calculation formula is:

[0117] R rec (%) = (m) con ×w CaF2,con ) / (m ore ×w CaF2,ore )

[0118] Where m con For the dry quality of the concentrate, w CaF2,con m is the mass fraction of CaF2 in the concentrate. ore To the total mass of raw ore input, w CaF2,ore This represents the mass fraction of CaF2 in the raw ore.

[0119] After flotation, a sample is taken from the bottom of the tank and the dry mass m of the sediment at the bottom of the tank is measured. sed , with m sed The settling rate (SR) of the slime is calculated as the ratio of the total mass of fine slime in the raw ore to the total mass of the slime.

[0120] SR (%) = m sed / (m ore ×f slime )

[0121] Where f slime The mass fraction of fine mineral mud with a particle size of <10μm in the raw ore;

[0122] Foam half-life determination: After foaming stabilizes in step 3, record the time required for the foam layer height to drop to 50% of its initial height.

[0123] Foam breakage rate: After the foam stabilizes, record the initial total foam height H0, and calculate the initial total foam volume V0 = cross-sectional area of ​​the channel × H0; scrape the foam horizontally back and forth once at a uniform speed, while simultaneously starting the negative pressure pump for 5 seconds; let it stand for 10 seconds until all the broken foam falls back to the slurry layer, and read the height H1 of the remaining intact foam. The volume of the remaining intact foam V1 = cross-sectional area of ​​the channel × H1; perform three parallel tests and take the average value. Foam breakage rate η (%) = (V0 - V1) / V0 = (H0 - H1) / H0, where V0 is the volume of intact foam before disturbance; V1 is the volume of intact foam remaining after scraper + negative pressure disturbance.

[0124] Table 1 Flotation performance test results

[0125]

[0126] Combination Figure 1-2 As can be seen from the data in the table above:

[0127] In this invention, the foaming start time of fluorite slurry is concentrated in the range of 2.7-3.8 min, and the overall foaming speed is stable and fast. The foaming time of pure oleic acid comparative example 1 reaches 8.4 min, while the foaming times of comparative example 2 without modified sodium maleate and comparative example 5 with only block ether are 3.1 min and 6.9 min, respectively. The foaming time of unmodified betaine comparative example 7 is 5.5 min. This indicates that the combination of modified alkyl amphoteric betaine and fatty alcohol polyoxyethylene polyoxypropylene block ether can significantly improve the emulsification rate of oleic acid and shorten the foaming cycle. The settling rates ranged from 11.8% to 18.3%. Comparative Example 1, lacking any dispersing component, showed the highest settling rate due to the large amount of fine mineral mud deposited. Comparative Example 2, with the modified sodium maleate removed, had a settling rate of 25.4%, while Comparative Example 6, using ordinary polymaleic acid instead of the modified product, had a settling rate of 22.9%. These two comparative examples fully demonstrate that the modified sodium maleate oligomer of this invention, relying on its controllable molecular weight and high-density sodium carboxylate groups, provides both electrostatic repulsion and steric hindrance, enabling long-term dispersion of fine fluorite mineral mud. Combined with mechanical scraping at the bottom of the tank, this significantly reduces the amount of mud accumulation at the bottom, minimizing ineffective reagent consumption. Comparative Examples 3 and 4, lacking polyol temperature-resistant additives and foam-regulating components, showed a decrease in settling rate despite having modified sodium maleate, but the foaming speed was still significantly worse. This indicates that all four components are indispensable, and a single component cannot simultaneously meet both foaming and mud-suppressing requirements.

[0128] In this invention, the foam half-life is stably maintained between 100-130 s, and the foam breakage rate is consistently within the range of 5.3%-6.7%, achieving an optimal balance between foam toughness and liquid film strength. Comparisons of data from Comparative Examples 4, 7, and 3 show that the foam liquid film is highly susceptible to rupture under scraper shearing and negative pressure suction, causing fluorite particles to fall back into the slurry. This results in metal loss, and the chaotic foam grayscale and texture significantly reduce the accuracy of the visual recognition algorithm. While Comparative Example 6 exhibits a foaming speed close to the embodiment, its foam breakage rate is higher, and its foam uniformity is inferior to the standard foam regulated by modified betaine. Comparative Example 1 has a foam half-life of only 1 min, a breakage rate of 13.8%, and exhibits easy foam collapse, a mixture of large and small bubbles, and an inability to stably form a bimodal grayscale image, making it completely unsuitable for use with automated foam monitoring and scraping equipment. This indicates that modified alkyl amphoteric betaine can regulate foam pore size and improve liquid film elasticity, while ethylene glycol-sorbitol compound additives stabilize the liquid film structure. The synergistic effect of the two ensures that the foam half-life and breakage rate remain within the preset standard range of the process, meeting the foam quantification requirements of fully automated flotation.

[0129] In this invention, the CaF2 grade of the concentrate is distributed between 92.1% and 95.2%, and the fluorite recovery rate is 83.6% to 90.8%. In contrast, the concentrate grade of Comparative Example 1 is only 88.6%, and the recovery rate is as low as 71.3%. Poor reagent dispersion and foam collapse result in a large amount of fluorite not being collected with the foam. Compared with the optimal example 8, the recovery rate of Comparative Examples 2-7 is 8-16 percentage points lower, showing a significant difference in the quality improvement and recovery effect. When foam control components are lacking, the foam carries more gangue and mud, leading to a decline in concentrate grade. When dispersion and sedimentation inhibitors are lacking, the fine mud deposited at the bottom of the tank continuously consumes oleic acid, resulting in insufficient concentration of effective collector reagent and incomplete fluorite flotation. Without polyol additives, the foam stability is poor, and the loss of fluorite during the foam scraping process is aggravated.

[0130] Therefore, it can be concluded that the present invention limits the synergistic effect of the quaternary compound modified synergist, and at the same time matches the entire set of process parameters such as 15-30cm foam operation height, ash quantification, and adaptive negative pressure foam scraping, so as to take into account multiple objectives such as rapid foaming, inhibition of sludge deposition, standardized and controllable foam, high fluorite concentrate grade and high recovery rate. It is suitable for 24-hour unmanned automated fluorite flotation production line under high and low temperature conditions and has significant advantages for industrial application.

[0131] Furthermore, based on the oleic acid synergists of Example 8, Comparative Example 1, and Comparative Example 5, steps S2 to S4 were repeated at slurry temperatures ranging from 0°C to 50°C, and the t values ​​at each temperature were recorded. foam R rec And foam breakage rate. Among them, the low temperature condition (<10℃) is maintained by an external ice-salt water bath, and the high temperature condition is maintained by an external hot water bath.

[0132] Table 2 Comparison of wide temperature adaptability

[0133]

[0134] Combination Figure 3-5 As can be seen from the table above:

[0135] In this invention's process, visual monitoring consistently yielded "yes" results across all test temperatures from 0℃ to 50℃, with minimal fluctuations in key indicators. Even at 0℃, the time to stabilize foaming to the specified height only increased to 10.8 minutes, while the recovery rate remained at 82.4%, foam breakage was controlled below 10%, and the grayscale texture parameters (grayF and foR) consistently fell within the acceptable ranges of 40-60 and 0.12-0.22, respectively. It is speculated that the ethylene glycol-sorbitol polyol compound additive within the slurry system forms an antifreeze and foam-stabilizing system, modified amphoteric betaine continuously regulates the foam structure, and modified sodium polymaleate ensures the suspension of fine mud. These multiple components synergistically offset the negative impacts of high and low temperatures on oleic acid emulsification, foaming, and ore-carrying capacity. In contrast, the two comparative groups only met the standards within a limited ambient temperature range; in extreme hot and cold environments, the foam parameters rapidly exceeded the acceptable thresholds. This demonstrates that the invention's compound formulation achieves standardized foam production across the entire temperature range of the slurry, making it suitable for 24-hour uninterrupted intelligent flotation production.

[0136] Comparative Example 1, using only pure oleic acid, only triggered foam scraping at two mild temperatures: 25°C and 15°C. When the temperature rose to 35°C and dropped to 5°C, the foam breakage rate increased rapidly, with grayF falling below 40 and foR exceeding the standard range, rendering the judgment invalid. Pure oleic acid lacks emulsifying, foam-stabilizing, and temperature-resistant additives; even small temperature fluctuations resulted in uneven oleic acid dispersion, foam collapse, and increased gangue inclusions. At 50°C and 0°C, the foaming time exceeded 20 minutes, leading to a drop in recovery rate and essentially losing its industrial sorting value. Comparative Example 5 lacked foam-stabilizing betaine and polyols, only meeting the standards at 25°C, 15°C, and 35°C. Once reaching 50°C or below 5°C, the foam toughness decreased significantly, and texture parameters became disordered. Comparing the temperature ranges of the two comparative examples shows that relying solely on emulsifying components can only slightly broaden the applicable range. Without foam control and temperature-resistant buffering components, the machine vision recognition and negative pressure foam scraping conditions cannot be maintained stably whenever the slurry temperature deviates from the mild range.

[0137] A horizontal comparison of data from three groups of samples at the same temperature reveals that, regardless of whether the temperature is low or high, the foaming time continuously increases as the temperature deviates from the 25°C baseline, while the fluorite recovery rate declines simultaneously, and the foam breakage rate gradually increases. The slurry system in this invention relies on the synergistic effect of multiple functional components to buffer the negative effects of temperature, resulting in a significantly lower increase in foaming time and a much smaller decrease in recovery rate compared to the two comparative groups. From an industrial production perspective, seasonal water temperature fluctuations are common in mineral processing plants. Pure oleic acid and single additives are significantly limited by the season, requiring frequent adjustments to reagent dosage and stirring time. The process of this invention does not require changes to operating parameters based on water temperature, automatically determines foam removal across the entire temperature range, and offers significant advantages in production stability and economic benefits.

[0138] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A fluorite flotation process based on oleic acid synergist, characterized in that, Includes the following steps: (1) Sodium carbonate is added to the flotation receiving unit to adjust the pH of the pulp to 8.5-10.0, and then oleic acid and oleic acid synergist are added in sequence. Foaming is carried out by stirring and dual-channel air supply. The mass ratio of oleic acid to oleic acid synergist is 4:1-6:

1. The oleic acid synergist is obtained by mixing ethylene glycol and sorbitol, adding fatty alcohol polyoxyethylene polyoxypropylene block ether, modified alkyl amphoteric betaine and modified sodium polymaleate oligomer in sequence, stirring evenly, and then sealing and allowing it to stand for aging. (2) After the foam layer to be foamed is stably formed, the foam is collected by the foam scraper and then collected into the concentrate receiving unit by negative pressure.

2. The fluorite flotation process based on oleic acid synergist according to claim 1, characterized in that, In step (1), the mass fraction of each component in the oleic acid synergist is as follows: fatty alcohol polyoxyethylene polyoxypropylene block ether 30%-40%, modified alkyl amphoteric betaine 22%-27%, modified sodium maleate oligomer 26%-34%, and ethylene glycol and sorbitol compound polyol auxiliaries 12%-18%.

3. The fluorite flotation process based on oleic acid synergist according to claim 2, characterized in that, The fatty alcohol polyoxyethylene polyoxypropylene block ether has an EO addition number of 10-14 and a PO addition number of 6-10.

4. The fluorite flotation process based on oleic acid synergist according to claim 2, characterized in that, The modified alkyl amphoteric betaine is synthesized from C12-C14 fatty acids through a three-stage process of amidation, ethoxylation of mono-epoxy groups, and quaternization of carboxymethyl groups, with an active ingredient content of not less than 35% by mass fraction.

5. The fluorite flotation process based on oleic acid synergist according to claim 2, characterized in that, The modified sodium maleate oligomer was prepared by maleic anhydride-acrylic acid free radical oligomerization, hydrolysis and neutralization.

6. The fluorite flotation process based on oleic acid synergist according to claim 1, characterized in that, In step (1), the amount of sodium carbonate added relative to the mass of the slurry is 0.08%-0.15%, and the pH of the slurry is 9.0-9.5; the mass ratio of oleic acid to oleic acid synergist is 5:

1.

7. The fluorite flotation process based on oleic acid synergist according to claim 6, characterized in that, During the slurry preparation and foaming process, the stirring and foaming time is 3-8 minutes, the air supply pressure is 0.02-0.08 MPa, and the slurry temperature range is 0℃-50℃.

8. The fluorite flotation process based on oleic acid synergist according to claim 1, characterized in that, In step (2), the foam layer is imaged in real time by an image acquisition device installed on the top of the flotation receiving unit. The foam layer thickness, equivalent diameter of a single bubble, foam layer development parameters and average foam gray value are extracted. When the foam layer thickness is 15-30cm, the equivalent diameter of a single bubble is 1.0-1.6mm, the foam layer development parameters are not less than 0.4 and the average foam gray value is 40-60, the bubble scraping action is triggered.

9. The fluorite flotation process based on oleic acid synergist according to claim 8, characterized in that, When any one of the following parameters is met—foam layer thickness, equivalent diameter of a single bubble, foam layer development parameters, and average foam gray value—scraping and collecting is paused, and the stirring and foaming time is extended until all parameters meet the standards again, at which point scraping and collecting are automatically restarted.

10. The fluorite flotation process based on oleic acid synergist according to claim 1, characterized in that, In step (2), the foam half-life is 100-130s and the foam breakage rate is ≤11%.

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