A method of producing and using an armored bubble dispersion

Abstract

The present application aims to provide a kind of armored bubble dispersion liquid generation and use method, belong to the field of flotation technology, the present application will hydrophobicity micro-nano particle be preloaded on the surface of flotation bubble by homogeneous shearing effect and construct hydrophobicity armored layer, to promote the adhesion between bubble and coal.Hydrophobicity micro-nano particle loaded on the surface of bubble is armored particle.Hydrophobicity micro-nano particle on bubble will change the mechanism of action between bubble and coal surface, from traditional uniform gas-liquid interface to inhomogeneous gas-solid-liquid interface and coal surface action.By the method of the present application, it is helpful to improve the overall flotation efficiency.

Description

Technical Field

[0001] This invention belongs to the field of flotation technology, specifically relating to a method for generating and using armored bubble dispersion. Background Technology

[0002] Flotation is a separation method based on the differences in the physicochemical properties of mineral surfaces. Its core lies in controlling the hydrophilicity or hydrophobicity of mineral surfaces using reagents, and then using air bubbles to separate target minerals from other minerals. The specific process is as follows: Collectors and other reagents are added to the pulp pre-processor to make the target mineral surface hydrophobic (air-loving), while keeping the non-target minerals hydrophilic, thereby increasing the difference in floatability. The pulp is then fed into the flotation machine. As the impeller rotates at high speed, a negative pressure zone is created in the pulp, drawing in air and breaking it into small bubbles. The stirring impeller thoroughly mixes the air with the pulp. Hydrophobic mineral particles adhere to the bubbles and float to the surface to form a foam layer, while hydrophilic minerals sink to the bottom, achieving separation.

[0003] Current flotation technologies rely on mechanical agitation and fluid shear force to disperse collectors (such as kerosene and diesel), resulting in large and uneven oil droplets. These large droplets fail to adequately wet the mineral surface, causing some collectors to remain in the slurry or be lost with the tailings, leading to reagent waste. To compensate for inefficient dispersion and adsorption, excessive collectors must be added, significantly increasing production costs.

[0004] Furthermore, when used for coal slime flotation, it exhibits poor adaptability to difficult-to-float coal slime and coarse-grained coal, resulting in low recovery rates. Difficult-to-float coal slime (such as oxidized coal and low-rank coal) has a highly hydrophilic surface or well-developed pores, making it difficult for conventional shear-dispersing collectors to form a stable hydrophobic film on its surface, leading to a low probability of mineral adhesion to air bubbles. Coarse-grained coal, due to its large mass and inertia, is difficult to effectively collide with air bubbles in a mechanically stirred flow field; even after collision, it easily detaches from the bubbles due to high shedding forces. Both exhibit weak bubble-particle interaction, slow flotation rates, and decreased clean coal recovery rates. Summary of the Invention

[0005] This invention addresses the problems of waste of collectors and slow flotation rate in existing flotation technologies by providing a method for generating and using armored bubble dispersion.

[0006] This invention utilizes homogeneous shearing to pre-load hydrophobic micro / nano particles onto the surface of flotation bubbles, constructing a hydrophobic armor layer to promote adhesion between the bubbles and coal. The hydrophobic micro / nano particles loaded onto the bubble surface are the armor particles. The loading of hydrophobic micro / nano particles onto the bubbles alters the interaction mechanism between the bubbles and the coal surface, transforming it from a traditional homogeneous gas-liquid interface to a heterogeneous gas-solid-liquid interface interacting with the coal surface.

[0007] The core idea of ​​this invention is to utilize the homogenizer to form an armored bubble dispersion within a container, thereby improving bubble stability and flotation recovery rate. The specific technical solution includes the following key points: (1) Order of adding materials: Add appropriate amounts of surfactant, non-polar hydrocarbon oil, armor particles and air to water in sequence. Surfactant should be dissolved in deionized water first to reduce the surface tension of water; non-polar hydrocarbon oil should be dispersed into micron-sized oil droplets in the presence of surfactant to form an oil phase emulsion system; armor particles should be added after the oil phase is dispersed.

[0008] (2) Formation of armored bubbles: Armored particles adsorb oil droplets through hydrophobic interaction to form an oil film encapsulation structure; after the particles complete the oil film encapsulation, the airflow is cut into microbubbles by high-speed shearing. At this time, the armored particles preferentially adsorb onto the surface of the bubbles due to their hydrophobicity to form an armor layer.

[0009] The present invention specifically adopts the following technical solution: A method for generating an armored bubble dispersion includes the following steps: S1. Add deionized water to the container, place a homogenizer in the middle of the container, and turn on the homogenizer. S2. Add the surfactant through the port of the container; S3. After the surfactant is dissolved, add non-polar hydrocarbon oil to the container; S4. Add hydrophobic micro / nano particles to the container; S5. Air is introduced into the container, and under the action of the homogenizer, an armored bubble dispersion is formed.

[0010] Furthermore, the surfactant includes one of sodium dodecyl sulfonate or hexadecyltrimethylammonium bromide; the nonpolar hydrocarbon oil includes one of kerosene or diesel oil; and the hydrophobic micro / nano particles include one of carbon black particles or biochar particles.

[0011] Furthermore, the ratio of deionized water, surfactant, nonpolar hydrocarbon oil, and hydrophobic nanoparticles is 300mL:0.82g:300μL:0.6g.

[0012] A method for using an armored bubble dispersion includes the following steps: S1. Select a single-cell flotation machine, and connect the flow valve, peristaltic pump, container for preparing armored bubble dispersion, and air compressor in sequence through a hose at the air inlet of the flotation machine. S2. Weigh the coal sample and water and add them to the flotation cell of the flotation machine. Start the flotation machine to stir and form a slurry. S3. After stirring for 2 minutes, add the collector and continue stirring to ensure that the collector reacts fully with the slurry. S4. After stirring for 1 minute, add the foaming agent. At the same time, under the control of the flow valve, the armored bubble dispersion is fed into the mechanical stirring mechanism of the flotation machine through the peristaltic pump. After stirring for 30 seconds, open the air inlet valve to perform the foam scraping operation. S5. Collect the flotation clean coal products in four time periods: 0-30s, 30-60s, 60-120s, and 120-180s. Then filter the obtained products, dry them, weigh them, and calculate the clean coal yield and combustible gas recovery rate.

[0013] Furthermore, the concentration of the slurry in S2 is 80 g / L, and the aeration rate is 0.2 m³ / L. 3 / h.

[0014] Furthermore, the collector described in S3 is kerosene, and the ratio of the collector to the coal sample is 0.8 kg of collector per ton of coal sample.

[0015] Furthermore, the foaming agent in S4 is 2-octanol, and the dosage ratio to the coal sample is 80g of foaming agent per ton of coal sample; the air intake volume is 0.2 m³ / s. 3 / h.

[0016] Furthermore, the stirring speed in S2, S3, and S4 is 1600 r / min.

[0017] The principle of this invention is as follows: Micro- and nano-particles (carbon black, biochar particles) coated with non-polar hydrocarbon oil films are loaded onto the surface of bubbles to form an armor layer, constructing a hydrophobic gas-liquid interface to enhance the hydrophobic gravitational field and promote the adhesion of coal to bubbles, bringing positive effects similar to oil bubble flotation. In addition, the micro- and nano-rough structures formed at the gas-liquid interface will stimulate local instability of the liquid film between the bubble and the coal, accelerating the rupture of the liquid film.

[0018] By modulating the physicochemical properties (surface electrical properties, functional groups, and hydrophobicity) of armor particles based on coal surface characteristics, the functionality of armored bubbles can be enhanced. Loading armor particles can alter the zeta potential at the gas-liquid interface, thereby reducing the bubble-coal adhesion barrier by adjusting the double-layer structure of the gas-liquid interface. Modifying the surface functional groups (such as hydroxyl, alkyl chains, and amino groups) of armor particles can enhance the adhesion process by binding them to oxygen-containing functional groups on the coal surface through hydrogen bonds / chemical bonds.

[0019] Additional benefits of armored bubbles include enhanced coal-bubble adhesion stability. When armored bubbles adhere to coal, the well-developed micro-roughness of the coal surface embeds micro- and nano-particles along the three-phase contact line, forming a mechanical interlock that inhibits the movement of the three-phase contact line, resulting in a pinning effect that raises the desorption energy barrier and improves the adhesion stability between the bubbles and coal. Furthermore, the lattice-like structure formed by the dense packing of armored particles increases the elastic modulus of the gas-liquid interface, endowing the bubbles with excellent resistance to shear deformation. This is similar to the mechanism by which the self-assembly behavior of colloidal particles at the liquid-liquid interface enhances the stability of Pickering emulsions. Moreover, the armor layer prevents bubble coalescence; when the liquid film thins to the distance between the armored particles, the physical barrier formed by the armored particles themselves inhibits bubble coalescence. Therefore, the improved mechanical properties of armored bubbles can suppress bubble coalescence and reduce the probability of coal desorption caused by mineralized bubbles impacting the slurry-foam layer interface.

[0020] The beneficial effects of this invention are as follows: 1. Uniformity and Controllability of Bubble Size: Homogenizers, through high-speed shearing and centrifugal action, break down gas into uniform microbubbles with a narrow particle size distribution (e.g., standard deviation <10%). Smaller bubbles have a larger specific surface area, increasing mineral attachment sites and improving flotation rates. By adjusting the homogenizer's operating time, rotation speed, or homogenizer head structure, bubbles with different particle sizes (e.g., nanobubbles <1000 nm, microbubbles 1~100 μm) can be flexibly prepared to meet the differentiated separation needs of fine and coarse minerals. Traditional methods are prone to "bubble aggregation," leading to uneven particle size, with large bubbles easily breaking and small bubbles easily dissolving. In contrast, the monodisperse bubbles prepared by homogenizers have higher stability (half-life extended to 2-3 times that of traditional bubbles), reducing ineffective bubble loss during flotation.

[0021] 2. Interface coating efficiency and uniformity: The strong shear force of the homogenizer can enable the bubble surface to quickly and uniformly adsorb the reagent and hydrophobic particles, forming a dense "armor layer".

[0022] 3. Improve flotation efficiency: Mineral particles can adhere more effectively to the surface of armored bubbles, especially for easily detachable coarse particles, which helps to improve flotation recovery rate.

[0023] 4. Improve flotation kinetics: Armored bubbles can improve the flotation kinetics of mineral particles, shorten the induction time, accelerate the flotation speed, and improve the overall flotation efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the armor bubble structure formed by the present invention; Figure 2 This is a schematic diagram of the flotation test apparatus of the present invention; Figure 3This is a graph showing the flotation test results of Example 1; Figure 4 This is a graph showing the average particle size and half-life of the armored bubbles at different rotation speeds in Example 3. Among them: 1-flotation machine; 2-flow valve; 3-peristaltic pump; 4-three-necked flask; 5-homogenizer; 6-air compressor. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, specific embodiments of the invention are described in detail, but are not limited thereto. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products; and unless otherwise specified, the methods used are methods commonly used in the art.

[0026] Example 1 Preparation of armor bubble dispersion Add 300 mL of deionized water to a three-necked flask. Place a homogenizer (model FJ-400) at the middle neck of the flask, ensuring it is in working order. First, add 10 mL of water from both ends. -2 Sodium dodecyl sulfonate (mol / L) was dissolved and 300 μL of kerosene was added, followed by 0.6 g of carbon black granules. Air was then introduced through both ends, and an armored bubble dispersion was formed under the action of a homogenizer.

[0027] The homogenizer operates for 5-10 minutes, the stirring speed is 12000 r / min, the particle size of the armored bubbles is 10-120 μm, and the half-life of the armored bubbles is 65 min 40 s.

[0028] like Figure 1 As shown, the armor particles (carbon black) adsorb oil droplets through hydrophobic interaction to form an oil film encapsulation structure; after the particles complete the oil film encapsulation, the airflow is cut into microbubbles by high-speed shearing. At this time, the armor particles preferentially adsorb onto the surface of the bubbles due to their hydrophobicity to form a coated armor shell.

[0029] Example 2 flotation test Using a 0.5L single-cell flotation machine of model XFD, first connect the flow valve, peristaltic pump, three-necked flask for preparing armored bubble dispersion, and air compressor in sequence through a hose at the air inlet of the flotation machine, so as to allow the armored bubble group to be introduced into the flotation machine to collide with the coal to complete the flotation test.

[0030] First, weigh out 40g of coal sample and add 0.5L of water to the flotation cell. Start the flotation machine and stir to fully mix and form a slurry. Maintain the slurry concentration at 80g / L to ensure uniformity and stability. Set the impeller speed to 1600r / min and the aeration rate to 0.2m³ / min. 3 / h. After stirring for 2 minutes, add kerosene as a collector at a dosage of 0.8 kg / t, and continue stirring to ensure the collector fully reacts with the slurry. After stirring for 1 minute, add octanol as a frother at a dosage of 80 g / t. Simultaneously, using the armored bubble dispersion formed by the homogenizer, the armored bubble group is introduced into the mechanical stirring mechanism of the flotation machine through a peristaltic pump under the control of the flow valve. After stirring for 30 seconds, perform a skimming operation. Collect clean coal products in four time periods: 0–30 s, 30–60 s, 60–120 s, and 120–180 s. The obtained products are then filtered, dried, weighed, and the clean coal yield and combustible gas recovery rate are calculated according to the formula.

[0031] The calculation formula is as follows: ;in, γ The yield of refined coal is expressed as a percentage (%). m j The mass of clean coal (g) m r The mass of the flotation feed (g).

[0032] ;in, ε The percentage of combustible gas recovery is %. γ The percentage of clean coal yield (%) A j Ash content of refined coal (%) A r Ash content (%) of flotation feed.

[0033] In conventional flotation, no armored bubble dispersion is added. The remaining steps and dosage are the same as in Example 2. The flotation test is completed in the flotation machine, and the clean coal yield is calculated in the same way.

[0034] The results are as follows Figure 3 As shown, by Figure 3 It can be seen that the formation of armored bubbles improves the cumulative combustible recovery rate to some extent. In particular, the cumulative combustible recovery rate of flotation with armored bubbles introduced in Example 2 is 84.67%, while the cumulative combustible recovery rate of conventional flotation is 77.48%.

[0035] Calculations showed that Example 2 had a clean coal yield of 69.37% and a clean coal ash content of 9.28%, while conventional flotation had a clean coal yield of 60.18% and a clean coal ash content of 8.76%. It can be seen that the introduction of armored bubbles during the flotation process significantly improved both the clean coal yield and the combustible gas recovery rate.

[0036] Example 3 By adjusting the homogenizer's working time, rotation speed, or homogenizer head structure, other experiments and results can be flexibly prepared for bubbles with different particle size requirements (such as nanobubbles <1000nm, microbubbles 1~100μm).

[0037] Add 300 mL of deionized water to a three-necked flask. Place a homogenizer (model FJ-400) at the middle neck of the flask, ensuring it is in working order. First, add 10 mL of water from both ends. -2 Sodium dodecyl sulfonate (mol / L) was dissolved and then 300 μL of kerosene was added, followed by 0.6 g of carbon black particles. Air was then introduced through both ends, and an armored bubble dispersion was formed under the action of a homogenizer. The homogenizer was operated for 5-10 min, and the rotation speed was adjusted to 6000, 8000, 10000, 12000, and 15000 r / min. The particle size of the armored bubbles was determined using a phase Doppler particle analyzer (PDA). Before the measurement, the particle size measurement accuracy was calibrated sequentially using standard polystyrene microspheres of 100 nm, 1 μm, 10 μm, and 100 μm. The equivalent refractive index of the armored bubbles was set to 1.45, the scattering mode was set to (refractive dominance), the effective measurement count was set to ≥1000, and the trigger mode was set to "automatic triggering of particle crossing the measurement body". Three sets of data were continuously collected, each set containing ≥1000 effective signals, with an interval of 10 min between sets to avoid the influence of flow field fluctuations. The half-life of the armored bubbles at five different rotation speeds was also recorded.

[0038] The results are as follows Figure 4 As shown, the average particle size of the armored bubbles gradually decreases with increasing rotational speed. At a rotational speed of 15000 r / min, the average particle size is 0.871 μm. The half-life of the armored bubbles also gradually increases with increasing rotational speed, reaching 4341 s at 15000 r / min. Experimental measurements demonstrate that adjusting the homogenizer's operating parameters can prepare micron and nanobubbles with different particle size requirements.

[0039] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for generating an armored bubble dispersion, characterized in that: The steps are as follows: S1. Add deionized water to the container, place a homogenizer in the middle of the container, and turn on the homogenizer. S2. Add the surfactant through the port of the container; S3. After the surfactant is dissolved, add non-polar hydrocarbon oil to the container; S4. Add hydrophobic micro / nano particles to the container; S5. Air is introduced into the container, and under the action of the homogenizer, an armored bubble dispersion is formed; The ratio of deionized water, surfactant, nonpolar hydrocarbon oil, and hydrophobic nanoparticles is 300mL: 0.82g: 300μL: 0.6g.

2. The method for generating an armored bubble dispersion according to claim 1, characterized in that: The surfactant includes one of sodium dodecyl sulfonate or hexadecyltrimethylammonium bromide; the nonpolar hydrocarbon oil includes one of kerosene or diesel oil; and the hydrophobic micro / nano particles include one of carbon black particles or biochar particles.

3. A method of using the armored bubble dispersion as described in claim 1, characterized in that: Includes the following steps: S1. Select a single-cell flotation machine, and connect the flow valve, peristaltic pump, container for preparing armored bubble dispersion, and air compressor in sequence through a hose at the air inlet of the flotation machine. S2. Weigh the coal sample and water and add them to the flotation cell of the flotation machine. Start the flotation machine to stir and form a slurry. S3. After stirring for 2 minutes, add the collector and continue stirring to ensure that the collector reacts fully with the slurry. S4. After stirring for 1 minute, add the foaming agent. At the same time, under the control of the flow valve, the armored bubble dispersion is fed into the mechanical stirring mechanism of the flotation machine through the peristaltic pump. After stirring for 30 seconds, open the air inlet valve to perform the foam scraping operation. S5. Collect the flotation clean coal products in four time periods: 0-30s, 30-60s, 60-120s, and 120-180s. Then filter the obtained products, dry them, weigh them, and calculate the clean coal yield and combustible gas recovery rate.

4. The method of using the armored bubble dispersion according to claim 3, characterized in that: The concentration of the slurry described in S2 is 80 g / L.

5. The method of using the armored bubble dispersion according to claim 3, characterized in that: The collector described in S3 is kerosene, and the ratio of the collector to the coal sample is 0.8 kg of collector per ton of coal sample.

6. The method of using the armored bubble dispersion according to claim 3, characterized in that: The foaming agent described in S4 is 2-octanol, and the dosage ratio to the coal sample is 80g of foaming agent per ton of coal sample; the air intake valve has an air intake rate of 0.2 m³ / s. 3 / h.

7. The method of using the armored bubble dispersion according to claim 3, characterized in that: The stirring speed described in S2, S3, and S4 is 1600 r / min.

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