Synthesis process of environment-friendly coal washing flotation reagent collecting agent

Abstract

The invention relates to the technical field of coal washing, and particularly discloses a synthesis process of an environment-friendly coal washing flotation reagent collecting agent. According to the process, abietic acid modified vegetable oil is used as a raw material, the amphiphilic structure collecting agent is constructed through a three-step method, the obtained collecting agent has high collecting performance and environmental compatibility, and the clean coal recovery rate can be increased while the dosage of the agent is reduced; aromatic ring adsorption on the surface of coal is enhanced through a rigid abietic acid skeleton, hydrophilicity is improved through a sulfonated chain, and efficient mineralization of coal particles is achieved in combination with the interface regulation and control effect of a biosurfactant. No toxic solvent participates in the whole process, the byproduct is only water vapor, the method is suitable for flotation of various coal types such as coking coal, gas coal and lignite, and the industrial problem that the surface hydrophobicity of oxidized coal is poor is particularly solved.

Description

Technical Field

[0001] The invention relates to the technical field of coal washing, and in particular to a synthesis process of an environmentally friendly coal washing flotation agent collector. Background Art

[0002] Traditional coal flotation collectors primarily rely on petroleum-based products such as diesel and kerosene. Their simple molecular structures and lack of polar functional groups result in poor adsorption selectivity on coal particle surfaces and high collector consumption. Non-polar hydrocarbons are particularly difficult to penetrate the hydration membrane barrier of low-rank and oxidized coals, which are rich in surface oxygen-containing functional groups. This results in insufficient clean coal recovery and carryover losses from tail coal. Furthermore, petroleum-based agents have poor biodegradability (<30%), and long-term use can easily lead to excessive COD accumulation in surface waters. Aromatic hydrocarbons pose a significant ecotoxicity risk.

[0003] While recent bio-based alternatives have shown some improvement in environmental performance, they still have significant limitations. Esterified vegetable oil collectors suffer from poor hydrolysis stability of their ester bonds, resulting in a short flotation froth life. Directly modified waste oils and fats, due to high impurity content, are not suitable for high-ash coals. Compounded collectors, however, are prone to stratification and precipitation due to poor component compatibility. Simultaneously improving collector efficiency, environmental adaptability, and ecological safety remains a technical bottleneck. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] In view of the above problems in the prior art, the inventors proposed the present invention.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a synthesis process for an environmentally friendly coal washing flotation agent collector.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a synthesis process of an environmentally friendly coal washing flotation agent collector, comprising the following steps: 1. (a) Esterification: Mix rosin acid and vegetable oil in a mass ratio of 1:(0.8-1.5), add nano zinc oxide catalyst (0.3%-0.8% by mass of rosin acid), and react at 220-250°C under nitrogen for 2-3 hours until the acid value is ≤8mgKOH / g; (b) Sulfonation modification: The esterification product is cooled to 80-100°C, and sodium bisulfite (5%-10% by weight of the total mass of the esterification product) and trisodium citrate (15%-25% by weight of the sodium bisulfite) are added as a chelating agent, and the reaction is carried out at this temperature for 1.5-2 hours to generate a sulfonated group (-SO3H); (c) Compounding and synergistic enhancement: The sulfonated product and the biosurfactant were mixed in a mass ratio of (4-6):1, and 3%-5% of the total mass of the compounding system as an ethanol cosolvent was added. The mixture was stirred at 60°C for 40 minutes to obtain a yellow-brown viscous liquid collector.

[0008] As a preferred solution of the synthesis process of an environmentally friendly coal washing flotation agent collector described in the present invention, the vegetable oil is selected from tea seed oil, rapeseed oil or waste catering oil with an acid value of ≤2 mgKOH / g, and the waste catering oil needs to be molecular distilled to remove free fatty acids and impurities.

[0009] As a preferred solution of the synthesis process of an environmentally friendly coal washing flotation agent collector described in the present invention, the nano zinc oxide catalyst has a particle size of 30-50 nm, a specific surface area of ​​≥40 m² / g, and is activated at 300°C for 1 hour before the esterification reaction.

[0010] As a preferred embodiment of the synthesis process of an environmentally friendly coal washing flotation agent collector according to the present invention, the sulfonated modified product in step (b) is subjected to Fourier transform infrared spectroscopy and is qualified only if a characteristic absorption peak of -SO3 is present at 1170 cm⁻¹.

[0011] As a preferred solution of the synthesis process of an environmentally friendly coal washing flotation agent collector described in the present invention, the biosurfactant is a rhamnolipid or sophorolipid with a purity of ≥90%, and a sodium lignin sulfonate dispersant of 2%-5% by mass of the sulfonated product is added simultaneously during compounding.

[0012] As a preferred solution of the synthesis process of an environmentally friendly coal flotation agent collector described in the present invention, the collector obtained in step (c) must meet the following physicochemical indicators: viscosity 35-55 mPa·s at 25°C, flash point ≥150°C, and biodegradability ≥78%.

[0013] An environmentally friendly coal washing flotation agent collector, comprising the following components in percentage by mass: Rosin acid-esterified vegetable oil matrix: 70%-85%; Sulfonated modified polar component: 10%-20%; Biosurfactant: 5%-15%.

[0014] As the application of the environmentally friendly coal washing flotation agent collector in coal slime flotation of the present invention, wherein: Applicable to coking coal, gas coal, lignite and oxidized coal with ash content of 15%-45%; The flotation pulp concentration is 80-120g / L, the pH value is 7.5-8.5, and the reagent dosage is 0.8-1.5kg / t dry coal slime.

[0015] A flotation system comprises a flotation machine, a pulp pretreatment device and a reagent adding device, wherein: the reagent adding device is loaded with the collector; The system is equipped with an online viscosity monitoring module to adjust the collector addition rate in real time to match changes in slurry concentration.

[0016] As a preferred solution of the flotation system described in the present invention, the slurry pretreatment device has a built-in ultrasonic disperser with a frequency of 20-40 kHz and an action time of 5-10 minutes, which is used to enhance the spreading and adsorption of the collector on the surface of the oxidized coal.

[0017] Beneficial effects of the present invention: The present invention solves the technical bottleneck of weak affinity and poor selectivity of traditional petroleum-based collectors for the surface of coal particles through the π-π directional adsorption effect of the rigid skeleton of rosin acid and the aromatic rings on the coal surface, combined with the hydrophobic association effect of long-chain alkanes in vegetable oils. The -SO3H group introduced by sulfonation modification not only gives the molecule amphiphilic properties, but also destroys the hydration film barrier on the coal surface through hydrogen bond reconstruction, allowing the agent to spread spontaneously on the surface of low-rank coal and oxidized coal. The supramolecular assembly formed by the compounded biosurfactant significantly enhances the strength and stability of the bubble mineralization membrane, improving flotation efficiency at the microscopic level.

[0018] The natural degradation pathway of the rosin acid-vegetable oil system is highly compatible with the microbial metabolic network. The collector molecules are gradually broken down by the microbial community into small, water-soluble molecules that are ultimately mineralized, completely avoiding the risk of persistent accumulation of petroleum-based agents in the ecosystem. The process produces no toxic byproducts, and the sulfite produced by sodium bisulfite sulfonation can be recycled, achieving an atom-economic design of the reaction pathway. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it constitute a separate or selective embodiment that is mutually exclusive with other embodiments.

[0022] Example 1 This embodiment provides a synthesis process of an environmentally friendly coal washing flotation agent collector, specifically, basic process verification and coking coal flotation application.

[0023] (1) Raw materials and pretreatment As an embodiment, the synthesis process uses the following raw materials: Abietic acid: industrial grade, abietic acid content of 88.5%, vacuum dehydrated at 100℃ for 2 hours before use to control moisture ≤ 0.3%; Vegetable oil: refined tea seed oil, acid value 0.8mg KOH / g, adsorbed on 3A molecular sieve to reduce moisture content to ≤0.1%; Catalyst: Nano zinc oxide, particle size 30-50nm, specific surface area 40nm / 45m² / g, further activated at 300℃ for 1 hour to enhance surface activity; Sulfonating agent: Sodium bisulfite (AR grade), crushed through a 200-mesh sieve to increase the reaction contact area.

[0024] (2) Step-by-step synthesis process Esterification reaction stage Specifically, the operation steps are as follows: 200g of rosin acid and 180g of tea seed oil are placed in a high-pressure reactor, and 1.2g of activated nano zinc oxide catalyst is added. Under nitrogen protection, the temperature is programmed: The first stage: keep the temperature at 150℃ for 30 minutes to achieve complete melting of the raw materials; The second stage: heating to 230°C and reacting for 150 minutes.

[0025] Furthermore, samples were taken every 30 minutes to detect the acid value, and the endpoint acid value was controlled to be ≤8 mg KOH / g (detection value 7.2 mg KOH / g, corresponding to an esterification rate of 93.1%).

[0026] Sulfonation modification stage The esterification product was cooled to 90°C, and 18 g of sodium bisulfite and 3.6 g of trisodium citrate were added. The temperature was maintained at 90±2°C and stirred for 110 minutes.

[0027] As a quality control method, the sulfonated product was subjected to FTIR analysis (Nicolet iS50) at 1172 cm -1 A strong -SO3 stretching vibration peak appears at .

[0028] Compounding and synergistic stage Cool the sulfonated product to 60°C, then add 40g of rhamnolipid (compound ratio: surfactant = 5.4:1), 12g of anhydrous ethanol (3.8% of the total weight of the mixture), and 8g of sodium lignin sulfonate. Stir at constant temperature for 40 minutes until the mixture is homogeneous, resulting in a brownish-yellow, transparent, viscous liquid.

[0029] (III) Product characterization and application verification Physical and chemical properties testing Viscosity: 42.7 mPa·s; Flash point: 158℃; Biodegradation rate: 81.2%.

[0030] Flotation test (coking coal, ash content 28.7%) Results: Clean coal yield was 93.6% (ash content 9.8%), tail coal ash content was 71.5%, and combustible recovery was 95.3%. Compared to a diesel collector (clean coal yield 89.2% under the same conditions), the recovery rate increased by 4.4 percentage points.

[0031] Example 2 This embodiment provides a synthesis process of an environmentally friendly coal washing flotation agent collector.

[0032] Specifically, waste oil regeneration and gas coal flotation applications.

[0033] (1) Raw material substitution and process adjustment As an environmentally friendly implementation method, the raw materials are optimized as follows: Vegetable oil substitute: recycled rapeseed oil (acid value 1.5 mg KOH / g, deacidified to ≤ 2 mg KOH / g by molecular distillation); Biosurfactant: Sophorolipid (enzymatically synthesized, purity 90.7%); Change in chelating agent: Disodium EDTA replaces trisodium citrate (the dosage is 20% of the mass of sodium bisulfite).

[0034] (2) Key process optimization Esterification reaction: rosin acid: rapeseed oil = 1:1.2 (mass ratio), reaction temperature 245°C, time 120 minutes.

[0035] Compounding system: main agent: sophorolipid = 5:1, add 4% ethanol as a cosolvent, and simultaneously turn on the ultrasonic disperser (frequency 40kHz, action for 10 minutes) to solve the problem of uneven dispersion caused by waste oil impurities.

[0036] (III) Comparison of technical effects (gas coal, ash content 32.1%) Furthermore, the sugar ring structure of sophorolipids enhances the elasticity of the bubble membrane (Marangoni effect), and the sulfonic acid groups of sulfonated rapeseed oil esters are directionally adsorbed on the oxygen-containing sites on the coal surface, solving the problem of gas-coal hydration membrane.

[0037] Example 3 This embodiment provides a synthesis process of an environmentally friendly coal washing flotation agent collector.

[0038] Furthermore, the flotation of high oxidation lignite was implemented industrially.

[0039] (1) Raw material innovation and equipment linkage To solve the technical problem of strong hydrophilicity of oxidized coal surface, the following solution is adopted: Source of rosin acid: rosin waste (rosin acid content 71.3%, purified by ethanol recrystallization); Vegetable oil: waste cooking oil (acid value 4.2 mg KOH / g, purified by two-stage molecular distillation to an acid value ≤ 2 mg KOH / g); Equipment linkage: The collector addition device is combined with the flotation system's online viscosity monitoring module to adjust the addition rate in real time.

[0040] (2) Strengthening process design Photocatalytic esterification: 0.5% nano-TiO2 (P25 type) was added during the esterification stage, and the reaction was shortened to 100 minutes under ultraviolet light source (wavelength 365nm).

[0041] Ultrasonic pretreatment: The slurry is treated with an ultrasonic disperser (frequency 20kHz, action for 5 minutes) to promote the spreading of the agent on the surface of the oxidized coal.

[0042] (3) Industrial application data The production line was implemented (slurry concentration 110g / L, pH=8.2), and the results are as follows: Environmental safety verification: BOD5 / COD=0.62 (>0.3 biodegradability threshold); Fish 96h LC 50 >100mg / L (actually non-toxic).

[0043] In summary, the core of the present invention is to construct a "natural structural adaptability" collection system. The π-π stacking effect (van der Waals distance ≤ 3.8Å) of the tricyclic phenanthrene skeleton of rosin acid and the aromatic ring of coal macromolecules essentially simulates the natural occurrence form of humic acid in coal rock. This structural similarity at the molecular level enables the collector to penetrate the hydration membrane to form a directional anchor. The long-chain alkanes of vegetable oil wrap the non-polar regions of coal particles through hydrophobic association, and the matching degree of its carbon chain length (C16-C18) with the alkane side chain in coal is significantly higher than that of petroleum-based short-chain hydrocarbons (C10-C12). The -SO3H group introduced by sulfonation modification does not simply increase hydrophilicity. Its key role is: on the one hand, the negative charge generated by ionization repels the anions on the surface of the gangue (such as SiO4 4 ⁻), improving selectivity; on the other hand, destroying the hydration sheath of oxygen-containing groups (such as -COOH) on the coal surface through hydrogen bond reconstruction. This dual mechanism is particularly evident in the flotation of oxidized coal in Example 3 - when the hydroxyl density on the lignite surface reaches 4.2 / nm², the strong proton acceptor properties of the sulfonic acid group can effectively disassemble the water molecule network.

[0044] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A synthesis process of an environmentally friendly coal washing flotation agent collector, characterized by: The following steps are involved: (a) Esterification: Mix rosin acid and vegetable oil in a mass ratio of 1:(0.8-1.5), add nano zinc oxide catalyst (0.3%-0.8% by mass of rosin acid), and react at 220-250°C under nitrogen for 2-3 hours until the acid value is ≤8mgKOH / g; (b) Sulfonation modification: Cool the esterification product to 80-100°C, add 5%-10% of the total mass of the esterification product in the form of sodium bisulfite and 15%-25% of the mass of sodium bisulfite in the form of trisodium citrate as a chelating agent, and keep the reaction at this temperature for 1.5-2 hours to generate a sulfonated group (-SO3H); (c) Compounding and synergistic enhancement: The sulfonated product and the biosurfactant were mixed in a mass ratio of (4-6):1, and 3%-5% of the total mass of the compounding system as an ethanol cosolvent was added. The mixture was stirred at 60°C for 40 minutes to obtain a yellow-brown viscous liquid collector.

2. The process for synthesizing an environmentally friendly coal washing flotation collector according to claim 1, characterized in that: The vegetable oil is selected from tea seed oil, rapeseed oil or waste catering oil with an acid value of ≤2 mgKOH / g, and the waste catering oil needs to be molecularly distilled to remove free fatty acids and impurities.

3. The synthesis process of an environmentally friendly coal washing flotation agent collector according to claim 2, characterized in that: The nano zinc oxide catalyst has a particle size of 30-50 nm and a specific surface area of ​​≥40 m² / g, and is activated at 300° C. for 1 hour before the esterification reaction.

4. The process for synthesizing an environmentally friendly coal washing flotation collector according to claim 1, characterized in that: The product after sulfonation modification in step (b) needs to be detected by Fourier transform infrared spectroscopy, and it is qualified only if the characteristic absorption peak of -SO3 appears at 1170cm⁻¹.

5. The process for synthesizing an environmentally friendly coal washing flotation collector according to claim 1, characterized in that: The biosurfactant is a rhamnolipid or sophorolipid with a purity of ≥90%, and a sodium lignin sulfonate dispersant is added simultaneously in an amount of 2%-5% by mass of the sulfonated product during compounding.

6. The process for synthesizing an environmentally friendly coal washing flotation collector according to claim 1, characterized in that: The collector obtained in step (c) must meet the following physical and chemical indicators: viscosity of 35-55 mPa·s at 25°C, flash point ≥150°C, and biodegradation rate ≥78%.

7. An environmentally friendly coal washing flotation collector according to any one of claims 1 to 6, characterized in that: Contains the following components in percentage by mass: Rosin acid-esterified vegetable oil matrix: 70%-85%; Sulfonated modified polar component: 10%-20%; Biosurfactant: 5%-15%.

8. The use of an environmentally friendly coal washing flotation collector in coal slime flotation according to claim 7, characterized in that: Applicable to coking coal, gas coal, lignite and oxidized coal with ash content of 15%-45%; The flotation pulp concentration is 80-120g / L, the pH value is 7.5-8.5, and the reagent dosage is 0.8-1.5kg / t dry coal slime.

9. A flotation system comprising a flotation machine, a pulp pretreatment device and a reagent adding device, characterized in that: The reagent adding device is loaded with the collector according to claim 7; The system is equipped with an online viscosity monitoring module to adjust the collector addition rate in real time to match changes in slurry concentration.

10. A flotation system according to claim 9, characterized in that: The slurry pretreatment device has a built-in ultrasonic disperser with a frequency of 20-40 kHz and an action time of 5-10 minutes, which is used to enhance the spreading and adsorption of the collector on the surface of the oxidized coal.

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