Emulsified waste oil for floatation reagent, its preparation method and application

Abstract

The present application relates to a kind of emulsified waste oil for floating reagent and its preparation method and application, belong to the field of flotation technology, to solve at least one of the problems such as poor stability, poor dispersibility, poor flotation effect of emulsified waste oil prepared by existing method.The preparation of the emulsified waste oil of the present application adds PSBMA and tween 80 as a compound floating reagent, which can increase the stability of the emulsion, PSBMA is a long-chain polymer with amphiphilic properties, when it reacts with waste oil, each macromolecular polymer adsorbed on the interface is similar to multiple connected small molecules and side-by-side aggregation, when macromolecular polymer desorbs from the interface, the entire backbone needs to be removed, resulting in the need for more energy to break through the high energy barrier, thereby effectively improving the stability of the emulsion, the probability of collision with the target mineral increases and the droplet is more easily contacted with the particle and spread on the surface, thereby effectively improving the flotation effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flotation, in particular to an emulsified waste oil for flotation reagent and a preparation method and application thereof. BACKGROUND

[0002] China is the largest coal producer and consumer in the world, and a large amount of coal-based solid waste such as fly ash and coal gasification slag will be generated in the process of coal mining and processing. At present, the utilization rate of coal-based solid waste is low, mainly because its low calorific value cannot be directly used as fuel, and the content of unburned carbon is relatively high and cannot be directly mixed with building materials. Therefore, carbon ash separation is the premise of large-scale utilization. Flotation has the advantages of simple operation, high recovery rate, etc., and is an effective way to realize carbon ash separation of coal gasification slag. However, the surface of coal gasification slag contains many oxygen-containing functional groups, has rich pores, and carbon ash is mixed with each other, so it is difficult for traditional non-polar hydrocarbon oil collectors to effectively adsorb and spread on the surface in the flotation process, resulting in large consumption of reagents, low economic benefits, and poor flotation effect with the increase of reagent dosage. Therefore, finding a green, efficient and low-cost collector is the key to realizing the resource utilization of coal gasification slag.

[0003] At present, the annual output of waste oil in China exceeds 1.2 billion liters. Waste oil usually contains hydrocarbons, esters, heteroatoms and other harmful substances, which pose a great threat to the environment and human health. However, the oxygen-containing functional groups in waste oil, such as C=O, C-O, O=C-O, etc., can selectively act on the surface of coal particles, effectively enhance the hydrophobicity, and have the potential of flotation reagent. However, direct use has problems such as large amount of reagent and poor recovery effect. Emulsion is a dispersion system in which one of the two incompatible liquids is uniformly dispersed in the form of small droplets in the other liquid. Emulsifying the flotation reagent can greatly improve the dispersibility of the reagent, increase the contact area with the coal particles, and thus obtain good coal gasification slag flotation recovery effect with less reagent.

[0004] In the prior art, waste oil is usually emulsified by various emulsifiers, but the emulsion stability is poor, and there are problems such as short stable time and serious demulsification. SUMMARY

[0005] In view of the above analysis, the present application aims to provide an emulsified waste oil for flotation reagent and a preparation method and application thereof, to solve at least one of the problems of poor stability, poor dispersibility and poor flotation effect of the emulsified waste oil prepared by the prior art.

[0006] In a first aspect, the present application provides a preparation method of an emulsified waste oil for flotation reagent, comprising the following steps:

[0007] (1) Centrifugal treatment of waste oil to obtain a stable waste oil system;

[0008] (2) adding the stable waste oil system into polysulfobetaine methacrylate and Tween 80 to obtain a mixed system, heating, stirring, and adding water to obtain emulsified waste oil.

[0009] Further, in step (1), the centrifugal speed is 9000-15000 r / min, and the centrifugal time is 5-15 min.

[0010] Further, in step (2), the average molecular weight of the polysulfobetaine methacrylate is greater than 3.5 KDa.

[0011] Further, in step (2), the mass of the polysulfobetaine methacrylate is 2-5% of the total mass of the mixed system, and the mass ratio of the polysulfobetaine methacrylate to Tween 80 is 1:3-3:1.

[0012] Further, in step (2), the stirring speed is 400-1200 r / min, the stirring time is 6-16 min, and the mass ratio of the added water to the waste oil is 1:2-2:1.

[0013] Further, in step (2), the polysulfobetaine methacrylate is prepared by the following method:

[0014] (a) adding a sulfobetaine methacrylate (SBMA) aqueous solution into an initiator under a nitrogen atmosphere to obtain a sulfobetaine methacrylate (SBMA) mixed solution;

[0015] (b) stirring and heating the sulfobetaine methacrylate (SBMA) mixed solution under a nitrogen atmosphere to obtain a polysulfobetaine methacrylate (PSBMA) solution;

[0016] (c) dialyzing and drying the polysulfobetaine methacrylate (PSBMA) solution to obtain a polysulfobetaine methacrylate (PSBMA) powder.

[0017] Further, in step (a), the mass concentration of the sulfobetaine methacrylate aqueous solution is 10-15%, and nitrogen is introduced for 8-12 min; preferably, the initiator is potassium persulfate, and the mass of the initiator is 0.2-0.4% of the mass of the SBMA.

[0018] Further, in step (c), the dialysis is performed by using a dialysis bag with a molecular weight of 3.5 KDa, and the dialysis time is 68-72 h.

[0019] In a second aspect, the present application provides emulsified waste oil prepared by the above method.

[0020] In a third aspect, the present application provides application of the above emulsified waste oil in coal-based solid waste flotation.

[0021] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0022] (1) The present application uses the long-chain amphiphilic polymer polymethacrylic acid sulfobetaine and Tween 80 as a complex flotation reagent to emulsify waste oil, and the sporadic action of polymethacrylic acid sulfobetaine and Tween 80 on the interface is combined to effectively improve the stability of the emulsion. At the same time, the waste oil is subjected to centrifugal pretreatment to improve its self-emulsification and emulsification capacity, and the high energy barrier and multi-factor regulated emulsification process brought by the aggregation of polymethacrylic acid sulfobetaine after polymerization greatly improve the stability and dispersibility of the waste oil emulsion, and the emulsion has a long existence period and more exposed surface functional groups, which can meet the needs of flotation of different production scales at different times;

[0023] (2) The present application PSBMA is a long-chain polymer with amphiphilicity, and when it reacts with waste oil, each macromolecular polymer adsorbed on the interface is similar to multiple small molecules connected together and aggregated side by side, and when the macromolecular polymer desorbs from the interface, the entire main chain needs to be removed, which requires more energy to break through the high energy barrier, thereby effectively improving the stability of the emulsion, increasing the collision probability with the target mineral, and making the droplets more easily contact and spread on the surface, thereby effectively improving the flotation effect;

[0024] (3) The PSBMA described in the present application can improve the flotation effect in two ways, one is direct action, the oxygen-containing functional groups of PSBMA can form hydrogen bonds with the hydrophilic sites on the surface of the unburned carbon in coal-based solid waste, improving the hydrophobicity of the hydrophilic region, and the straight-chain alkane structure of PSBMA can also produce van der Waals force with the methyl and methylene on the surface of the unburned carbon, thereby improving the floatability of the unburned carbon in coal-based solid waste; the other is indirect action, the average molecular weight of PSBMA is > 3.5KDa, which is larger than that of betaine, and the larger molecular weight requires more energy when it desorbs on the liquid film surface, ensuring the droplet structure of the emulsion, and the specific surface area of the droplet structure is larger, exposing more surface functional groups in the waste oil, thereby effectively improving the mineralization efficiency of the coal-based solid waste in the flotation process;

[0025] (4) The present application adjusts the amount of emulsifier, water-oil ratio, stirring speed, stirring time and other parameters to form a stable emulsified state of waste engine oil, which has good dispersibility and long-term stability, increases the collision probability with the target mineral, and makes the droplets more easily contact and spread on the surface, thereby effectively improving the flotation effect.

[0026] The technical solutions in the present application can be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the following description, and some advantages will become apparent from the description, or will be learned through implementation of the present application. The objectives and other advantages of the present application can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application. In the drawings:

[0028] Figure 1 Microscope image of emulsified waste oil prepared for Example 1;

[0029] Figure 2 Microscope image of emulsified waste oil prepared for Example 2;

[0030] Figure 3 Microscope image of emulsified waste oil prepared for Example 3;

[0031] Figure 4 Microscope image of emulsified waste oil prepared for Example 4;

[0032] Figure 5 Microscope image of emulsified waste oil prepared for Example 5;

[0033] Figure 6 Microscope image of emulsified waste oil prepared for Example 6;

[0034] Figure 7 Microscope image of emulsified waste oil prepared for Example 7;

[0035] Figure 8 Microscope image of emulsified waste oil prepared for Example 8;

[0036] Figure 9 Microscope image of emulsified waste oil prepared for Example 9;

[0037] Figure 10 Microscope image of emulsified waste oil prepared for Comparative Example 1;

[0038] Figure 11 Microscope image of emulsified waste oil prepared for Comparative Example 2;

[0039] Figure 12 Microscope image of emulsified waste oil prepared for Comparative Example 3;

[0040] Figure 13 Microscope image of emulsified waste oil prepared for Comparative Example 4;

[0041] Figure 14 Microscope image of emulsified waste oil prepared for Comparative Example 5. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this description. The drawings, together with the description, serve to explain the principles of the present application, and should not be used to limit the scope of the present application.

[0043] In one embodiment of the present application, a method for preparing emulsified waste oil for use in a floatation reagent is disclosed, comprising the following steps:

[0044] (1) centrifuging the waste oil to obtain a stable waste oil system;

[0045] (2) adding the stable waste oil system to polymethacrylic acid sulfobetaine (PSBMA) and Tween 80 to obtain a mixed system, heating, stirring, and adding water to obtain emulsified waste oil.

[0046] Compared with the prior art, the present application uses polymethacrylic acid sulfobetaine, a long-chain amphiphilic polymer, and Tween 80 as emulsifiers to emulsify the waste oil, thereby improving the stability of the emulsified waste oil. Meanwhile, the waste oil is subjected to centrifugal pretreatment to improve its self-emulsification and emulsification capacity, and the high energy barrier and multi-factor regulation of the emulsification process caused by the side-by-side aggregation of polymethacrylic acid sulfobetaine after polymerization greatly improve the stability and dispersibility of the emulsified waste oil, and the emulsion has a long existence period and more exposed surface functional groups, which can meet the needs of different production scales of flotation at different times.

[0047] The PSBMA of the present application is a long-chain polymer with amphiphilic properties. When it reacts with waste oil, each macromolecular polymer adsorbed on the interface is similar to multiple small molecules connected together and aggregated side by side. When the macromolecular polymer desorbs from the interface, the entire backbone needs to be removed, which requires more energy to break through the high energy barrier, thereby effectively improving the stability of the emulsion, increasing the collision probability with the target mineral, and making the droplets more easily contact and spread on the surface, thereby effectively improving the flotation effect.

[0048] In one embodiment, the waste oil in step (1) is waste engine oil, waste lubricating oil, or waste hydraulic oil.

[0049] Preferably, the viscosity of the waste oil is 1-200 mPa·s.

[0050] In one specific embodiment, in step (1), the centrifugal speed is 9000-15000 r / min, for example, 9000 r / min, 9500 r / min, 10000 r / min, 10500 r / min, 11000 r / min, 11500 r / min, 12000 r / min, 12500 r / min, 13000 r / min, 13500 r / min, 14000 r / min, 14500 r / min, 15000 r / min, and the centrifugal time is 5-15 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min.

[0051] It should be noted that the waste oil usually contains impurity particles such as metal scraps and oil sludge, and under high temperature conditions, carbon deposition, colloid and acidic substances will be generated due to thermal decomposition and oxidation. Solid impurities will destroy the interfacial tension, resulting in poor emulsion stability. The waste oil is subjected to centrifugal pretreatment in the present application to improve its self-emulsification and emulsification capacity, and further improve the emulsion stability.

[0052] In one specific embodiment, in step (2), the average molecular weight of the sulfobetaine methacrylate is > 3.5 KDa.

[0053] In one specific embodiment, in step (2), the mass of the sulfobetaine methacrylate is 2-5% of the total mass of the mixed system, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, and the mass ratio of the sulfobetaine methacrylate to Tween 80 is 1:3-3:1, for example, 1:3, 3:5, 3:4, 1:1, 3:2, 3:1.

[0054] It should be noted that when the emulsifier solution is mixed with oil, the hydrophilic group enters the water phase, and the lipophilic group enters the oil phase, forming an oil-water interfacial film. When the emulsifier concentration is too small, it is not enough to form a dense interfacial film, and the emulsion will quickly break and demulsify due to insufficient interfacial film strength. When the emulsifier concentration reaches 5%, further increasing the dosage has little effect on the arrangement of molecules on the liquid film surface, so further increasing the dosage does not change the emulsion stability.

[0055] When the mass ratio of PSBMA and Tween 80 is too small, the desorption energy barrier of PSBMA is low, and it is easy to separate from the liquid film surface, so the emulsion stability is poor; when the mass ratio is too large, Tween 80 cannot be uniformly arranged on the liquid film surface, which will also reduce the emulsion stability.

[0056] In one specific embodiment, in step (2), the temperature is raised to 40-70°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C.

[0057] It should be noted that as the temperature increases, the thermal motion of oil, water and emulsifier molecules becomes intense, the diffusion capacity is enhanced, and the adsorption capacity of molecules at the oil-water interface is enhanced, but when the temperature is too high, the volume of small emulsion droplets formed after emulsification is small, and the buoyancy is greater than the gravity, finally showing oil-water separation instability.

[0058] In a specific embodiment, in step (2), the stirring speed is 400-1200 r / min, for example, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min, the stirring time is 6-16 min, for example, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, and the mass ratio of water to waste oil is 1:2-2:1, for example, 1:2, 1:1, 2:3, 2:1.

[0059] It should be noted that the stirring speed, stirring time and water / oil mass ratio are key factors, the stirring speed and stirring time will affect the energy input and turbulence intensity of the system, thereby affecting the droplet size and liquid film strength; the water / oil mass ratio mainly controls whether the emulsion formed during the emulsification process is oil-in-water or water-in-oil, and the emulsion prepared by the present application is oil-in-water emulsion, which has good dispersibility in water phase slurry.

[0060] In a specific embodiment, in step (2), the polymethacrylic acid sulfobetaine is prepared by the following method:

[0061] (a) adding an initiator to a methacrylic acid sulfobetaine (SBMA) aqueous solution under a nitrogen atmosphere to obtain a methacrylic acid sulfobetaine (SBMA) mixed solution;

[0062] (b) stirring and heating the methacrylic acid sulfobetaine (SBMA) mixed solution in a nitrogen environment to obtain a polymethacrylic acid sulfobetaine (PSBMA) solution;

[0063] (c) dialyzing and drying the polymethacrylic acid sulfobetaine (PSBMA) solution to obtain polymethacrylic acid sulfobetaine (PSBMA) powder.

[0064] The structural formula of the methacrylic acid sulfobetaine (SBMA) in the present application is as follows:

[0065]

[0066] The chemical reaction equation for preparing the polymethyl methacrylate sulfobetaine in the present application is as follows:

[0067]

[0068] In one specific embodiment, in step (a), the mass concentration of the sulfobetaine methacrylate aqueous solution is 10-15%, for example, 10%, 11%, 12%, 13%, 14%, or 15%, and nitrogen is blown in for 8-12 min, for example, 8 min, 9 min, 10 min, 11 min, or 12 min.

[0069] It should be noted that when the mass concentration of the aqueous solution is too low, the molecular weight of the polymer is small and the polymer is easily removed during dialysis; when the mass concentration of the aqueous solution is too high, part of the monomers cannot participate in the reaction and the reaction time is prolonged. Nitrogen blowing is > 8 min to ensure that the air in the experimental system is completely removed and a nitrogen environment is created.

[0070] In one specific embodiment, in step (a), the initiator is potassium persulfate, and / or the mass of the initiator is 0.2-0.4% of the mass of SBMA, for example, 0.2%, 0.25%, 0.3%, 0.35%, or 0.4%.

[0071] In one specific embodiment, in step (b), the heating temperature is 55-65℃, for example, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, or 65℃, and the heating time is 8-12 h, for example, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h, or 12 h.

[0072] It should be noted that when the heating temperature is low, the energy of the system is insufficient to achieve the polymerization of polymethyl methacrylate sulfobetaine; the higher the temperature, the faster the decomposition rate of potassium persulfate, and when the temperature is too high, there is a certain risk in mixing potassium persulfate with organic matter; and the heating time is 8-12 h to ensure that the polymerization reaction can act completely.

[0073] In one specific embodiment, in step (c), the dialysis uses a dialysis bag with a molecular weight of 3.5 KDa, and the dialysis time is 68-72 h, for example, 68 h, 69 h, 70 h, 71 h, or 72 h.

[0074] It should be noted that the molecular weight of SBMA is 0.279 KDa, and a dialysis bag with a molecular weight of 3.5 KDa is selected to remove potassium persulfate, un-polymerized SBMA monomers and PSBMA oligomers by dialysis. If the molecular weight of the dialysis bag is too large, the polymerized PSBMA will be dialyzed out, and if the molecular weight of the dialysis bag is too small, the monomers cannot be removed, which will affect the emulsification effect. The dialysis time is > 68 h to ensure that the potassium persulfate, un-polymerized monomers and PSBMA oligomers are completely removed.

[0075] In a specific embodiment, in step (c), the drying is performed by freeze-drying at a temperature of -40 to -45 DEG C, for example, -40 DEG C, -41 DEG C, -42 DEG C, -43 DEG C, -44 DEG C, or -45 DEG C.

[0076] Another specific embodiment of the present application discloses an emulsified waste oil for use in floatation of coal-based solid waste prepared by the above method.

[0077] Another specific embodiment of the present application discloses an application of the above emulsified waste oil in floatation of coal-based solid waste.

[0078] The PSBMA can improve the floatation effect in two aspects. On the one hand, the oxygen-containing functional groups of PSBMA can form hydrogen bonds with the hydrophilic sites on the surface of unburned carbon in coal-based solid waste, thereby improving the hydrophobicity of the hydrophilic region. The straight-chain alkane structure of PSBMA can also form van der Waals forces with the methyl and methylene groups on the surface of unburned carbon, thereby improving the floatability of unburned carbon in coal-based solid waste. On the other hand, the average molecular weight of PSBMA is > 3.5 KDa, which is larger than that of betaine. The larger molecular weight requires more energy for desorption on the liquid film surface, thereby ensuring the liquid droplet structure of the emulsion. The liquid droplet structure has a larger specific surface area, which exposes more surface functional groups in the waste oil, thereby effectively improving the mineralization efficiency of coal-based solid waste in the floatation process.

[0079] In a specific embodiment, the application specifically comprises: dispersing the coal-based solid waste in water, adding the emulsified waste oil and stirring, then adding a frother and stirring, and scraping the froth to obtain unburned carbon and tail ash.

[0080] In a specific embodiment, the addition amount of the emulsified waste oil is 1-6 kg / t, for example, 1 kg / t, 2 kg / t, 3 kg / t, 4 kg / t, 5 kg / t or 6 kg / t.

[0081] In a specific embodiment, the frother is methyl isobutyl carbinol (MIBC).

[0082] Specifically, the addition amount of the frother is 1-5 kg / t, for example, 1 kg / t, 2 kg / t, 3 kg / t, 4 kg / t or 5 kg / t.

[0083] In one specific embodiment, the mass ratio of the coal-based solid waste to water is 1:50 to 1:10, for example, 1:50, 1:45, 1:40, 1:35, 1:30, 1:25, 1:20, 1:15, or 1:10.

[0084] The present application uses the long-chain amphiphilic polymer of sulfobetaine methacrylate and Tween 80 as a compound flotation reagent to emulsify waste oil, and the sporadic action of sulfobetaine methacrylate and Tween 80 on the interface is combined to effectively improve the stability of the emulsion. The compound flotation reagent of the present application has an increased collision probability with the target mineral, and the emulsion droplets are more easily in contact with the particles and spread on the surface, thereby effectively improving the flotation recovery rate of the target mineral.

[0085] The technical solutions of the present application are further explained and described below in combination with specific examples.

[0086] Example 1

[0087] A preparation method of emulsified waste oil for a flotation reagent, comprising the following steps:

[0088] (1) A 10% SBMA aqueous solution was placed in a 500 mL three-necked flask, nitrogen gas was passed for 12 min to create a nitrogen environment, 0.3% potassium persulfate initiator based on the mass of SBMA monomer was added, stirring was performed and heating was carried out to 60℃ under the nitrogen environment, and the temperature was kept constant for 12 h of polymerization reaction; after the polymerization reaction was completed, the solution was transferred to a dialysis bag with a molecular weight of 3.5 KDa, and dialysis was performed in ultrapure water for 72 h to remove monomers and oligomers; after the dialysis was completed, the supernatant was transferred to a freeze dryer and dried at -40℃ to obtain PSBMA powder, and the average molecular weight of the PSBMA was 42.3 KDa;

[0089] (2) The waste oil was placed in a centrifuge and centrifuged at 13000 r / min for 10 min to obtain a stable waste oil system;

[0090] (3) PSBAM and Tween 80 were added to 3 g of the stable waste oil to obtain a mixed system, the mass ratio of PSBAM to Tween 80 was 1:3, and the mixed system was placed on a 50℃ magnetic stirrer; after reaching the preset temperature, water was added dropwise while stirring, and the stirring was continued at 800 r / min for 12 min to obtain a yellowish emulsified waste oil; wherein the amount of water added was 1.4 times the mass of the waste oil, and the amount of PSBMA added was 3% of the total mass of the mixed system.

[0091] The waste oil in this example is waste engine oil.

[0092] Example 1-1

[0093] A method for preparing emulsified waste oil for a floatation reagent is the same as that of Example 1, except that step (1) is specifically as follows:

[0094] (1) A 12.5% SBMA aqueous solution was placed in a 500 mL three-necked flask, nitrogen was passed for 8 min to create a nitrogen environment, 0.2% potassium persulfate initiator based on the mass of the SBMA monomer was added, stirring and heating to 55°C under a nitrogen environment, keeping constant temperature for 8 h polymerization reaction; after the polymerization reaction was completed, the solution was transferred to a dialysis bag with a molecular weight of 3.5 KDa, dialyzed in ultrapure water for 68 h to remove monomers and oligomers; after dialysis was completed, the supernatant was transferred to a freeze dryer and dried at -42°C to obtain PSBMA powder, the average molecular weight of the PSBMA was 38.5 KDa;

[0095] Example 1-2

[0096] (1) A 15% SBMA aqueous solution was placed in a 500 mL three-necked flask, nitrogen was passed for 10 min to create a nitrogen environment, 0.4% potassium persulfate initiator based on the mass of the SBMA monomer was added, stirring and heating to 65°C under a nitrogen environment, keeping constant temperature for 10 h polymerization reaction; after the polymerization reaction was completed, the solution was transferred to a dialysis bag with a molecular weight of 3.5 KDa, dialyzed in ultrapure water for 72 h to remove monomers and oligomers; after dialysis was completed, the supernatant was transferred to a freeze dryer and dried at -45°C to obtain PSBMA powder, the average molecular weight of the PSBMA was 46.8 KDa;

[0097] Example 2

[0098] A method for preparing emulsified waste oil for a floatation reagent is the same as that of Example 1, except that in step (3), the amount of water added is 1.6 times the mass of the waste oil.

[0099] Example 3

[0100] A method for preparing emulsified waste oil for a floatation reagent is the same as that of Example 1, except that in step (3), the amount of water added is 1.8 times the mass of the waste oil.

[0101] Example 4

[0102] A method for preparing emulsified waste oil for a floatation reagent is the same as that of Example 1, except that in step (3), the amount of PSBMA added is 2.5% of the total mass of the mixed system.

[0103] Example 5

[0104] A preparation method of emulsified waste oil for a floating agent, the same as example 1, the difference is that in step (3), the added amount of PSBMA is 3.5% of the total mass of the mixed system.

[0105] Example 6

[0106] A preparation method of emulsified waste oil for a floating agent, the same as example 5, the difference is that in step (3), the stirring is continued at 600r / min for 12min, and a milky yellow emulsified waste oil is obtained.

[0107] Example 7

[0108] A preparation method of emulsified waste oil for a floating agent, the same as example 5, the difference is that in step (3), the stirring is continued at 1000r / min for 12min, and a milky yellow emulsified waste oil is obtained.

[0109] Example 8

[0110] A preparation method of emulsified waste oil for a floating agent, the same as example 5, the difference is that in step (3), the stirring is continued at 1000r / min for 6min, and a milky yellow emulsified waste oil is obtained.

[0111] Example 9

[0112] A preparation method of emulsified waste oil for a floating agent, the same as example 5, the difference is that in step (3), the stirring is continued at 1000r / min for 8min, and a milky yellow emulsified waste oil is obtained.

[0113] Example 10

[0114] Application of the emulsified waste oil prepared in example 1 in coal-based solid waste flotation, specifically including dispersing 30g of coal-based solid waste in a plexiglass flotation tank containing 500mL of deionized water, the loss on ignition of the coal-based solid waste is 32.62%, fully stirring for 1min, adding 1kg / t of the emulsified waste oil prepared in example 1 into the above flotation tank, stirring for 3min, then adding 3kg / t of MIBC frother, fully stirring for 3min, and then aerating and scraping bubbles for 4min; obtaining unburned carbon and tail ash.

[0115] Example 10-1

[0116] Application of the emulsified waste oil in coal-based solid waste flotation, the same as example 10, the difference is that the emulsified waste oil is prepared by the method of example 1-1.

[0117] Example 10-2

[0118] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 1-2.

[0119] Example 11

[0120] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 2.

[0121] Example 12

[0122] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 3.

[0123] Example 13

[0124] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 4.

[0125] Example 14

[0126] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 5.

[0127] Example 15

[0128] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 6.

[0129] Example 16

[0130] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 7.

[0131] Example 17

[0132] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 8.

[0133] Example 18

[0134] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of example 10, except that the emulsified waste oil is prepared by the method of example 9.

[0135] Example 19

[0136] An application of emulsified waste oil in coal-based solid waste flotation, which is the same as example 10, except that the amount of emulsified waste oil added is 3 kg / t.

[0137] Comparative example 1

[0138] A preparation method of emulsified waste oil for flotation reagent, which is the same as example 1, except that in step (1), a dialysis bag with a molecular weight of 3.0 KDa is used.

[0139] Comparative example 2

[0140] A preparation method of emulsified waste oil for flotation reagent, which is the same as example 1, except that in step (3), the amount of water added is 2.4 times the mass of waste oil.

[0141] Comparative example 3

[0142] A preparation method of emulsified waste oil for flotation reagent, which is the same as example 1, except that in step (3), the amount of PSBMA added is 1% of the total mass of the mixed system.

[0143] Comparative example 4

[0144] A preparation method of emulsified waste oil for flotation reagent, which is the same as example 5, except that in step (3), the stirring is continued at 300 r / min for 12 min to obtain a milky yellow emulsified waste oil.

[0145] Comparative example 5

[0146] A preparation method of emulsified waste oil for flotation reagent, which is the same as example 1, except that in step (3), Tween 80 is not added.

[0147] Comparative example 6

[0148] An application of emulsified waste oil in coal-based solid waste flotation, which is the same as example 10, except that the emulsified waste oil is prepared by the method of comparative example 1.

[0149] Comparative example 7

[0150] An application of emulsified waste oil in coal-based solid waste flotation, which is the same as example 10, except that the emulsified waste oil is prepared by the method of comparative example 2.

[0151] Comparative example 8

[0152] An application of emulsified waste oil in coal-based solid waste flotation, which is the same as example 10, except that the emulsified waste oil is prepared by the method of comparative example 3.

[0153] Comparative Example 9

[0154] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of Example 10, except that the emulsified waste oil is prepared by the method of Comparative Example 4.

[0155] Comparative Example 10

[0156] An application of emulsified waste oil in coal-based solid waste flotation is the same as that of Example 10, except that the emulsified waste oil is prepared by the method of Comparative Example 5.

[0157] Comparative Example 11

[0158] An application of waste oil in coal-based solid waste flotation is the same as that of Example 10, except that the waste oil is not emulsified and is directly used as waste engine oil.

[0159] Comparative Example 12

[0160] An application of waste oil in coal-based solid waste flotation is the same as that of Example 10, except that the amount of emulsified waste oil added is 0.5 kg / t.

[0161] Test Example 1

[0162] (1) The emulsified waste oils prepared by the methods of Examples 1-9 and Comparative Examples 1-5 were subjected to demulsification tests and microscopic tests, and the results are shown in Tables 1 and Figures 1-14 .

[0163] Table 1

[0164]

[0165] As can be seen from Examples 1, 1-1 and 1-2, the amount of initiator affects the average molecular weight of PSBMA. When the average molecular weight is small, the desorption energy barrier of PSBMA on the liquid film is reduced, resulting in a shorter demulsification time. As can be seen from Example 1 and Comparative Example 1, when the molecular weight of the dialysis bag is too small, the monomer cannot be removed, affecting the emulsification effect.

[0166] As can be seen from Examples 1, 2, 3 and Comparative Example 2, different water / oil ratios significantly affect the emulsion stability time and droplet size. When the mass fraction of surfactant is constant, the greater the mass fraction of water added, the weaker the liquid film strength, resulting in droplet coalescence, thus forming larger droplets that are prone to instability.

[0167] From Example 1, 4, 5 and Comparative Example 3, it can be seen that the emulsifier can reduce the interfacial tension and interfacial energy, so that the system tends to be stable, therefore, the increase of the amount of emulsifier can prolong the stable time of the emulsion and reduce the droplet diameter, when the amount of emulsifier is too low, the emulsifier molecules are not enough to be evenly distributed on the surface of the liquid film, therefore, the emulsion is easy to be unstable and the demulsification time is short;

[0168] From Example 5-9, it can be seen that the increase of stirring speed and stirring time can enhance the turbulence intensity in the system, so that the waste oil, water and emulsifier can act more fully, which is manifested as the increase of demulsification time and the decrease of droplet size;

[0169] From Example 5 and Comparative Example 4, it can be seen that when the stirring speed and time are too low, the emulsifier cannot act uniformly on the oil-water interface, so that the stability of the emulsion is reduced;

[0170] From Example 1 and Comparative Example 6, it can be seen that when Tween 80 is not added, the liquid film lacks sporadic distribution of small molecules, which leads to the decrease of the stability of the liquid film and the shortening of the demulsification time.

[0171] From Figures 1-3 and Figure 11 , it can be seen that different water-oil ratios can significantly affect the dispersion of the emulsion and the droplet size, when the mass fraction of the surfactant is constant, the greater the mass fraction of water added, the weaker the strength of the liquid film, which leads to the coalescence of the droplets, so that the droplets with large diameter are formed, the dispersion is poor and the emulsion is easy to be unstable;

[0172] From Figure 1 , 4 , 5 and Figure 12 , it can be seen that the emulsifier can reduce the interfacial tension and interfacial energy, so that the system tends to be stable, therefore, the increase of the amount of emulsifier can increase the strength of the liquid film, effectively improve the dispersion of the emulsion and reduce the droplet diameter of the emulsion;

[0173] From Figures 5-7 , it can be seen that the increase of stirring speed can enhance the turbulence intensity in the system, so that the waste oil, water and emulsifier can act more fully, therefore, with the increase of the stirring speed, the droplet size is reduced and the dispersion is better;

[0174] From Figures 7-9 and Figure 13 , it can be seen that when the stirring time is low, the emulsifier cannot act uniformly on the oil-water interface, therefore, the strength of the liquid film is low, which leads to the coalescence of the droplets, which is manifested as the increase of the droplet diameter and the poor dispersion, and when the stirring time is too long, air is brought into the emulsion system, which leads to the instability of the system and the coalescence of the droplets, therefore, the droplet diameter is large;

[0175] From Figure 9 and Figure 14It can be seen that when the emulsifier is only PSBMA without Tween 80, only the macromolecules of PSBMA exist on the surface of the liquid film and are arranged in a row, and the small molecules of Tween 80 are sporadically adsorbed, so the strength of the liquid film is poor, leading to easy deformation of the droplets and coalescence.

[0176] (2) The yield, loss on ignition and recovery rate of the unburned carbon and tailings obtained in Examples 10-19 and Comparative Examples 6-12 were tested, respectively, and the results are shown in Table 2.

[0177] Table 2

[0178]

[0179]

[0180] It can be seen from Examples 10, 10-1, 10-2 and Comparative Example 6 that as the molecular weight of PSBMA increases, the desorption barrier of PSBMA on the liquid film increases, so the stability of the emulsion is enhanced, which is manifested as the increase of the recovery rate of unburned carbon in flotation;

[0181] It can be seen from Example 10 and Comparative Example 7 that as the water / oil ratio increases, the stability of the emulsion droplets becomes poor, the droplets coalesce, and the exposed surface functional groups decrease, so the recovery rate of unburned carbon decreases;

[0182] It can be seen from Example 10 and Comparative Example 8 that as the amount of PSBMA increases, the stability of the liquid film is enhanced, the emulsion droplet size is smaller, and the collision probability with unburned carbon is higher, and at the same time, the polar functional groups of PSBMA can produce hydrogen bonding force with the surface of the oxygen-containing functional groups of unburned carbon, assisting the recovery of unburned carbon;

[0183] It can be seen from Example 10 and Comparative Example 9 that as the stirring speed and stirring time increase, the emulsion droplet size is smaller, and the collision probability with unburned carbon is higher during flotation, so the recovery rate of unburned carbon increases;

[0184] It can be seen from Example 10 and Comparative Example 11 that emulsification can significantly improve the dispersibility of waste oil in the ore slurry, and the emulsified waste oil has more exposed surface functional groups than the unemulsified waste oil, so the emulsified waste oil as a collector can obtain lower tail ash loss on ignition and higher unburned carbon recovery rate.

[0185] It can be seen from Example 10 and Comparative Example 12 that as the amount of emulsified waste oil increases, the selectivity of waste oil and the interaction with the surface of unburned carbon are enhanced, the hydrophobicity of the surface of unburned carbon is improved, the recovery rate of unburned carbon is higher, and the loss on ignition of tail ash is reduced. When the amount of emulsified waste oil is too low, the hydrophilic functional groups on the surface of unburned carbon cannot be completely covered, so the hydrophobicity is poor, leading to low recovery rate of unburned carbon.

[0186] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for the preparation of emulsified waste oil for use in a floatation reagent, characterized in that, The method comprises the following steps: (1) centrifuging the waste oil to obtain a stable waste oil system; (2) adding the stable waste oil system into sulfobetaine poly-methacrylic acid and Tween 80 to obtain a mixed system, heating, stirring, and adding water to obtain emulsified waste oil.

2. A process for the preparation of emulsified waste oil for use in a floatation reagent according to claim 1, characterized in that, In step (1), the centrifugation speed is 9000-15000 r / min, and the centrifugation time is 5-15 min.

3. A process for the preparation of emulsified waste oil for use in a floatation reagent according to claim 1, characterized in that, In step (2), the average molecular weight of the sulfobetaine poly-methacrylic acid is >3.5 KDa.

4. A process for the preparation of emulsified waste oil for use in a floatation reagent according to any one of claims 1 to 3, characterized in that, In step (2), the mass of the sulfobetaine poly-methacrylic acid is 2-5% of the total mass of the mixed system, and the mass ratio of the sulfobetaine poly-methacrylic acid to Tween 80 is 1:3-3:

1.

5. A process for the preparation of emulsified waste oil for use in a floatation reagent according to any one of claims 1 to 3, characterised in that, In step (2), the stirring speed is 400-1200 r / min, the stirring time is 6-16 min, and the mass ratio of the added water to the waste oil is 1:2-2:

1.

6. A process for the preparation of emulsified waste oil for use in a floatation reagent according to any one of claims 1 to 3, characterised in that, In step (2), the sulfobetaine poly-methacrylic acid is prepared by the following method: (a) adding an initiator into a sulfobetaine poly-methacrylic acid aqueous solution in a nitrogen atmosphere to obtain a sulfobetaine poly-methacrylic acid mixed solution; (b) stirring and heating the sulfobetaine poly-methacrylic acid mixed solution in a nitrogen atmosphere to obtain a sulfobetaine poly-methacrylic acid solution; (c) dialyzing and drying the sulfobetaine poly-methacrylic acid solution to obtain a sulfobetaine poly-methacrylic acid powder.

7. A process for the preparation of emulsified waste oil for use as a floatant agent according to claim 6, characterized in that, In step (a), the mass concentration of the sulfobetaine poly-methacrylic acid aqueous solution is 10-15%, nitrogen is introduced for 8-12 min, and / or the initiator is potassium persulfate, and the mass of the initiator is 0.2-0.4% of the mass of the sulfobetaine poly-methacrylic acid.

8. A process for the preparation of emulsified waste oil for use in a floatation reagent according to claim 6, characterized in that, In step (c), the dialysis is performed using a dialysis bag with a molecular weight of 3.5 KDa, and the dialysis time is 68-72 h.

9. Emulsified waste oil prepared by the method of any one of claims 1-8.

10. Use of the emulsified waste oil of claim 9 in coal-based solid waste flotation.

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