Preparation method of high-rheology calcium oxide composite emulsion and application thereof

Abstract

The application discloses a preparation method of a high-rheological calcium oxide composite emulsion and application thereof, and the preparation method comprises the following steps: after ball milling of calcium oxide and magnesium oxide, an organic dispersing agent is added, and stirring is uniformly conducted; then, a retarder and water are added, stirring is uniformly conducted, and the high-rheological calcium oxide composite emulsion is obtained after standing. The viscosity of the calcium oxide composite emulsion is lower than 0.3 mPa.s. The calcium oxide composite emulsion can be used for harmless disposal of phosphogypsum and treatment of phosphorus-containing and fluorine-containing wastewater, can effectively remove phosphate and fluorine ions, and the treated phosphogypsum and phosphorus-containing and fluorine-containing wastewater meet relevant environmental pollution standards. The preparation conditions of the composite emulsion are simple, the removal effect on pollutants is stable, and the composite emulsion is small in environmental pollution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial solid waste treatment and environmental protection, and relates to a preparation method of a calcium oxide composite emulsion with high rheological property and application thereof. BACKGROUND

[0002] I. Phosphogypsum

[0003] Phosphogypsum is a by-product in the production of phosphoric acid, and 4.5-5.5 tons of phosphogypsum is usually produced per ton of phosphoric acid. Phosphogypsum belongs to solid waste, and has the appearance of fine-particle powder in yellowish white, grayish white or blackish gray.

[0004] At present, there are mainly two ways to treat phosphogypsum in engineering: one is to discharge and abandon it, that is, to store and treat it; and the other is to utilize it after harmless treatment. Phosphogypsum has a relatively high water content and fine particles, and has strong flowability and migration. The migration of phosphogypsum is specifically manifested in that the soluble phosphorus, fluorine and metal sulfides can easily form leachate containing harmful substances under the action of natural precipitation, and the generated leachate can greatly pollute groundwater and surrounding soil.

[0005] Lime neutralization and solidification is the preferred process for non-water washing pretreatment of phosphogypsum, and lime neutralization has remarkable effect, simple process route, and low investment, and is practical and effective in the pretreatment mode, and is particularly suitable for phosphogypsum with low organic matter content and stable quality.

[0006] As a commonly used traditional lime agent, quicklime, slaked lime and composite alkali all have problems of low effective calcium content and weak alkalinity, and in the harmless process of phosphogypsum, the solidification effect of harmful components in phosphogypsum is poor, and it is difficult to change from the second type of solid waste to the first type of solid waste, so it is urgent to develop a new functional lime agent to solve the above technical bottlenecks, which is one of the hot issues in current research.

[0007] II. Phosphorus-containing and fluorine-containing wastewater

[0008] Phosphorus and fluorine are typical pollutants in water. Excessive phosphorus in water can lead to water eutrophication, which destroys the water ecological environment. The copper green microalgae that can easily grow in eutrophic water and the red tide water caused by eutrophication can cause great harm to human health and water plants and aquaculture. Excessive fluorine in water can enter the human body through the food chain, leading to fluorosis, and even harming the nervous system. China has strict control on these two pollutants. In the first level standard of "Integrated Wastewater Discharge Standard" (GB8978-1996), the limits of total phosphorus and fluorine (calculated as fluoride) are 0.5 mg / L and 10 mg / L, respectively.

[0009] At present, the methods for removing phosphorus and fluorine from wastewater mainly include biological method, chemical precipitation method, adsorption method, membrane technology treatment method, etc.; the methods for removing fluorine mainly include adsorption, precipitation, ion exchange and membrane separation technology, etc. Among them, the adsorption method is widely concerned due to its simple process, easy-to-control conditions, reliable operation and the purpose of achieving deep treatment. The adsorbent is the core of the adsorption method, and many adsorbents have been developed for the removal of phosphorus and fluorine. Some metal oxide adsorbents have attracted increasing attention of researchers due to their good adsorption selectivity because they can form coordination complexes with phosphorus and fluorine ions. - A large number of studies have proved that F generally exists in the form of F 3- at pH higher than 6; P exists in the form of (PO4) at pH higher than 10. Adding calcium base to wastewater can adjust pH, convert F and P into ion forms that can be treated, and react with F and P to generate CaF2 and Ca(PO4)3, etc. which are difficult to dissolve in water, thereby achieving the effects of removing phosphorus and fluorine from wastewater. If the pH is too high, the pH of the water body can be adjusted by using sulfuric acid, and the excess calcium ions can be removed at the same time. This makes calcium base have obvious advantages in wastewater treatment. However, the solubility of traditional calcium base (such as quicklime and slaked lime) in water is not high, and the dispersibility is poor, so a large amount of calcium cannot be utilized, causing waste and secondary pollution. Therefore, the performance improvement of calcium treatment agent is an important problem in the treatment of water body by calcium base method.

[0010] In the existing research, most adsorbents can only have good adsorption effect on one of the pollutants of phosphorus or fluorine, and do not have the ability to simultaneously and efficiently remove phosphorus and fluorine. In fact, phosphorus and fluorine often exist simultaneously in natural water bodies or groundwater. Therefore, it is necessary to develop and prepare a new type of composite adsorbent to achieve the purpose of simultaneously removing phosphorus and fluorine. SUMMARY

[0011] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a preparation method of a high-rheological calcium oxide composite emulsion and its application. The composite emulsion has high rheological property and stability, and can be used for phosphogypsum solidification and treatment of wastewater containing phosphorus and fluorine.

[0012] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0013] A preparation method of a high-rheological calcium oxide composite emulsion, comprising the following steps:

[0014] After ball milling the calcium oxide and magnesium oxide, an organic dispersant is added, stirred uniformly, then a retarder and water are added, stirred uniformly, and then the high-rheological calcium oxide composite emulsion is obtained after standing.

[0015] Further, the mass ratio of calcium oxide and magnesium oxide is (50-65):(20-35).

[0016] Further, the ball milling method adopts dry milling, the rotating speed is 240 rpm, and the ball milling time is 2.0-2.5 h.

[0017] Further, the organic dispersant is a mixture of methyl formate, ethylene glycol and ethyl acetate with a mass ratio of (20-30) g:(15-25) g:(5-15) g.

[0018] Further, the retarder is a starch solution with a mass fraction of 20%, and the mass ratio of the retarder and calcium oxide is (2-5):(50-65).

[0019] Further, all the stirring is carried out at 20-40 DEG C, and the stirring time is 0.5-1 h.

[0020] Further, the mass ratio of the amount of water and the amount of calcium oxide is 400-600 mL:50-65 g, and the standing time is 0.5-1 h.

[0021] The application of the high-rheological-property calcium oxide composite emulsion prepared according to the method to the harmless disposal of phosphogypsum and the treatment of phosphorus-containing and fluorine-containing wastewater.

[0022] Further, the high-rheological-property calcium oxide composite emulsion is added to the phosphogypsum powder, stirred uniformly, and then left to stand for 6-24 h; the amount of the high-rheological-property calcium oxide composite emulsion is 1% of the mass of the phosphogypsum powder.

[0023] Further, the high-rheological-property calcium oxide composite emulsion is added to the phosphorus-containing and fluorine-containing wastewater with a phosphorus concentration of 50-150 mg / L and a fluorine ion concentration of 50-400 mg / L, and the reaction is carried out for 0.5-1.5 h; the total mass of CaO and MgO in the high-rheological-property calcium oxide composite emulsion is 1%-2% of the mass of the phosphorus-containing and fluorine-containing wastewater.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] The novel calcium oxide composite medicament material provided by the application breaks through the technical defects of traditional lime medicament, mixes the calcium oxide and magnesium oxide after ball milling with organic dispersants and retarders, improves the emulsification degree of lime powder, reduces the influence on the environment, and prepares the calcium oxide composite emulsion with high rheological property. 2+ The calcium oxide composite emulsion with high rheological property has the characteristics of high rheological property, high activity, and high dispersity, can fully disperse and release calcium ions in wastewater, has fast effect and small dosage in pH adjustment, does not contain other pollution components, and does not have the problems of ordinary lime such as difficult solubility, excessive addition leading to high pH, easy caking, and heat release.

[0026] Further, the ball-milled calcium oxide and magnesium oxide powder are selected in the composite emulsion, the particle size and dispersion resistance of the solid material are reduced, and the stability and rheological property of the composite emulsion are increased.

[0027] Further, the use of methyl formate, ethylene glycol, and ethyl acetate greatly increases the dispersity of calcium oxide and magnesium oxide, promotes the full mixing and reaction of calcium oxide and magnesium oxide in the phosphogypsum or wastewater to be treated, and the effect after treatment is stable, and the organic components are volatile.

[0028] Further, the addition of the retarder starch enables the calcium oxide composite emulsion with high rheological property to be stored for a long time and reduces the stratification phenomenon.

[0029] The composite emulsion has good removal effect on phosphorus and fluorine pollutants, and can maintain relatively stable viscosity and pore size distribution in different temperature ranges due to its high rheological property. The use of the composite emulsion can effectively solve the problem of traditional wet treatment of calcium oxide, and improve the effect and treatment speed of calcium oxide in treating wastewater.

[0030] Further, the composite emulsion is directly dry-mixed in the process of treating phosphogypsum, and the dosage is 1% of the dry mass of phosphogypsum. After 6-24h curing reaction, the harmful substances such as soluble phosphorus, soluble fluorine, and ammonia nitrogen in the phosphogypsum are fully removed, and the removal rate is as high as 99.5% or more.

[0031] Further, the dosage of the composite emulsion is 1%-2% of the total volume of the wastewater, which can fully adsorb and combine the free fluorine and phosphate ions in the water, effectively treat the wastewater, and reduce the treatment cost. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Physical picture of high-rheology calcium oxide emulsifier prepared in the present application;

[0033] Figure 2 Physical picture of high-rheology calcium oxide composite emulsion prepared in Example 1;

[0034] Figure 3 Time-varying curve of soluble fluorine and soluble phosphorus concentration in phosphogypsum leaching solution in Example 5;

[0035] Figure 4 Time-varying curve of pH in phosphogypsum leaching solution in Example 5. DETAILED DESCRIPTION

[0036] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0037] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0038] The present application will be further described in detail below in combination with the drawings:

[0039] A preparation method of a high-rheology calcium oxide composite emulsion of the present application, comprising the following steps:

[0040] 1) Under normal temperature and pressure conditions, a certain mass ratio of calcium oxide and magnesium oxide is mixed and ball milled;

[0041] The calcium oxide and the magnesium oxide are all commercially available products, the effective calcium content is greater than or equal to 95%, the effective magnesium content is greater than or equal to 93%, and the amount ratio of the calcium oxide to the magnesium oxide is (50-65) g:(20-35) g, the ball milling mode is dry milling, the ball milling beads are agate beads with a diameter of 5 mm, the rotating speed is set to 240 rpm, and the ball milling time is 2.0-2.5 h.

[0042] 2) a certain amount of methyl formate, ethylene glycol and ethyl acetate is sequentially added to the solid powder after ball milling as an organic dispersant, and after being fully stirred and uniformly mixed, a prepared starch solution (retarder) is added drop by drop;

[0043] The amount ratio of the organic dispersants methyl formate, ethylene glycol and ethyl acetate is (20-30) g:(15-25) g:(5-15) g.

[0044] In the application, methyl formate, ethylene glycol and ethyl acetate are used as organic dispersants, which can better disperse the powder.

[0045] The mass fraction of the starch solution is 20%, and the addition amount is 2-5 g.

[0046] 3) then a certain amount of water is added and stirred again until fully mixed, and a high-rheological calcium oxide composite emulsion is prepared after standing for a certain period of time.

[0047] In steps 2) and 3), the magnetic stirrer is used for fully stirring and uniformly mixing, the temperature of the magnetic stirrer is adjusted to 20-40 DEG C, and the stirring time is 0.5-1 h.

[0048] In step 3), the volume of the added water is 400-600 mL, and the standing time is 0.5-1 h.

[0049] The high-rheological calcium oxide composite emulsion prepared in the application has high rheological property, and the viscosity value is less than 0.3 mPa s. The specific test method of the viscosity is as follows: a rotary viscometer is used, a certain volume of the liquid to be tested (the liquid is required to be placed in a circular container with a diameter of more than 12 cm) is measured, a corresponding range rotor is selected according to the approximate range of the viscosity, and then the rotor is operated and the viscosity value is read.

[0050] The low viscosity value represents high rheological property, and the stability is reflected in that the emulsion liquid does not precipitate after being placed for a long time (14 days), and the viscosity value still remains below 0.3 mPa s,

[0051] The application relates to a high-rheological calcium oxide composite emulsion prepared by adding an organic dispersant and a starch solution as a retarder to calcium oxide and magnesium oxide as main components, and the composite emulsion can effectively solidify soluble phosphorus and fluorine elements in phosphogypsum and purify wastewater containing phosphorus and fluorine.

[0052] The harmful components in the phosphogypsum include soluble phosphorus content of 20-150 mg / L, soluble fluorine content of 15-500 mg / L, and leaching liquid pH lower than 7. After conversion and addition, the total mass of CaO and MgO in the medicament (i.e. the high-rheological calcium oxide composite emulsion prepared by the application) is 1% of the dry basis mass fraction of the phosphogypsum, the solidification reaction time is 6-24 h, and after the high-rheological calcium oxide composite emulsion solidifies the phosphogypsum, the soluble phosphorus content is lower than 0.5 mg / L, the soluble fluorine content is lower than 10 mg / L, and the pH is 6-9. After the treated phosphogypsum is exposed to air and stacked for one month, the soluble phosphorus, the soluble fluorine and the pH still meet the above standards.

[0053] The phosphate concentration in the wastewater containing phosphorus and fluorine is 50-150 mg / L, and the fluorine ion concentration is 50-400 mg / L. The total mass of CaO and MgO in the medicament is 1%-2% of the wastewater mass fraction, the reaction time is 0.5-1.5 h, and after detection, the removal rates of the high-rheological calcium oxide composite emulsion for the phosphate and the fluorine ion are 99.2% and 97.5% respectively on average.

[0054] Example 1

[0055] The medicament is prepared by the following steps under room temperature and normal pressure conditions:

[0056] (1) 65g of calcium oxide with a mass fraction of 95% and 35g of magnesium oxide with a mass fraction of 93% are mixed and dry ground, the ball milling beads are 5mm diameter agate beads, the rotation speed is set to 240 rpm, and the ball milling time is 2.0h;

[0057] (2) methyl formate, ethylene glycol and ethyl acetate are mixed according to 25g:20g:15g, then added to the ground mixture, a magnetic stirrer is used to stir at 25℃ for 0.5h, and then 5g of a starch solution with a mass concentration of 20% is added;

[0058] (3) 600mL of water is added to the solution, a magnetic stirrer is used to stir at 25℃ for 0.5h again, and then the solution is left to stand for 1h to obtain the high-rheological calcium oxide composite emulsion.

[0059] The viscosity value of the prepared medicament is 0.136mPa·s, and the actual object diagram is as shown in Figure 2 It can be seen that the calcium oxide composite emulsion has high rheology.

[0060] Example 2

[0061] (1) 50 g of calcium oxide with a mass fraction of 95% and 30 g of magnesium oxide with a mass fraction of 93% were mixed and dry ground, the ball milling beads were made of agate beads with a diameter of 5 mm, the rotation speed was set to 240 rpm, and the ball milling time was 2.0 h;

[0062] (2) Methyl formate, ethylene glycol and ethyl acetate were mixed according to 20 g: 15 g: 5 g, then added to the ground mixture, stirred at 20°C for 1 h using a magnetic stirrer, and then 2 g of a starch solution with a mass concentration of 20% was added;

[0063] (3) 400 mL of water was added to the solution, stirred at 20°C for 1 h using a magnetic stirrer again, and then placed for 0.6 h to obtain a high-rheology calcium oxide composite emulsion.

[0064] Example 3

[0065] (1) 55 g of calcium oxide with a mass fraction of 95% and 25 g of magnesium oxide with a mass fraction of 93% were mixed and dry ground, the ball milling beads were made of agate beads with a diameter of 5 mm, the rotation speed was set to 240 rpm, and the ball milling time was 2.5 h;

[0066] (2) Methyl formate, ethylene glycol and ethyl acetate were mixed according to 30 g: 25 g: 10 g, then added to the ground mixture, stirred at 40°C for 0.5 h using a magnetic stirrer, and then 3 g of a starch solution with a mass concentration of 20% was added;

[0067] (3) 500 mL of water was added to the solution, stirred at 40°C for 0.5 h using a magnetic stirrer again, and then placed for 0.5 h to obtain a high-rheology calcium oxide composite emulsion.

[0068] Example 4

[0069] (1) 60 g of calcium oxide with a mass fraction of 95% and 32 g of magnesium oxide with a mass fraction of 93% were mixed and dry ground, the ball milling beads were made of agate beads with a diameter of 5 mm, the rotation speed was set to 240 rpm, and the ball milling time was 2.0 h;

[0070] (2) Methyl formate, ethylene glycol and ethyl acetate were mixed according to 22 g, 18 g, 12 g, then added to the ground mixture, stirred at 30°C for 0.8 h using a magnetic stirrer, and then 4 g of a starch solution with a mass concentration of 20% was added;

[0071] (3) 550 mL of water was added to the solution, stirred at 30°C for 0.8 h using a magnetic stirrer again, and then placed for 1 h to obtain a high-rheology calcium oxide composite emulsion.

[0072] Example 5

[0073] The application of the high-rheology calcium oxide composite emulsion in the treatment of phosphogypsum under room temperature and normal pressure conditions, the steps are as follows:

[0074] (1) Under laboratory conditions, phosphogypsum powder (dry basis about 100 grams) is added to a 500 ml beaker, and the high-rheology calcium oxide composite emulsion prepared in Example 1 is added at a dosage of 1% (i.e. the mass of the high-rheology calcium oxide composite emulsion is 1% of the mass of the phosphogypsum powder) and stirred thoroughly for 0.5 h to ensure uniform dispersion, and then left to stand for 6-24 hours.

[0075] (2) The solidified phosphogypsum is taken out at different times and immersed in pure water, and the initial concentration and the treated concentration of soluble phosphorus in the phosphogypsum are detected according to the National Standard for Determination of Total Phosphorus in Water (GB 11893-1989) using a spectrophotometer.

[0076] (3) The initial concentration and the treated concentration of soluble fluorine in the leaching solution are detected according to the National Standard for Detection of Fluoride Ions in Water (GB 11894-2014) using ion chromatography.

[0077] (4) The pH value of the leaching solution at different times is monitored using a pH meter, and after 24 h the phosphogypsum in the experiment is further placed and the above three indicators are detected again at different times until two weeks after the solidification reaction.

[0078] Figure 3 Therefore, in this example, the concentration of soluble fluorine and soluble phosphorus in the phosphogypsum leaching solution changes with time, and since the data changes greatly in the first 12 h, the data from 12 h to two weeks is selected;

[0079] Figure 4 Therefore, in this example, the pH of the phosphogypsum leaching solution changes with time. The experimental results show that the reaction is fully developed within 24 h, and the concentrations of the relevant substances in the leaching solution before and after 24 h are as follows:

[0080]

[0081] According to the Sewage Comprehensive Discharge Standard (GB 8978-1996) and the General Industrial Solid Waste Storage and Filling Pollution Control Standard (GB 18599-2020), the soluble phosphorus is less than 0.5 mg / L, the soluble fluorine is less than 10 mg / L, and the pH is between 6 and 9, which meets the standards. After two weeks, the soluble phosphorus detection is below the detection limit, the soluble fluorine detection value is 6.5 mg / L, and the pH value is stable at 7.3-7.5, which still meets the standards.

[0082] Example 6

[0083] The simulated wastewater was prepared in the laboratory for treatment, and the effect of the high-rheological calcium oxide composite emulsion was observed.

[0084] The prepared simulated wastewater contained F - =400mg / L, (PO4) 3- =120mg / L, pH=3. According to the calculation results of chemical equilibrium, 1% of the high-rheological calcium oxide composite emulsion of Example 1 was added to the water body, and water samples were taken at different times after the addition. According to the national standard for determination of total phosphorus in water (GB 11893-1989), the concentration of soluble phosphorus was detected by spectrophotometer, and the concentration of fluorine ion was detected according to the national standard for determination of fluorine ion in water (GB 11894-2014). After 6h, the detection results were: F - =6.14mg / L, (PO4) 3- =0.26mg / L, pH=7.72. According to the results of 6h, the P removal effect was more than 99%, F - The removal effect was more than 90%, the pH was controlled below 9, the dosage was small, the removal performance of pollutants was excellent. The data indicators all met the first level standard of the comprehensive wastewater discharge standard GB 8978-1996.

[0085] The above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A method for the preparation of a high rheology calcium oxide composite emulsion, characterized in that, The method comprises the following steps: After the calcium oxide and magnesium oxide are ball milled, an organic dispersant is added, stirred uniformly, then a retarder and water are added, stirred uniformly, and after standing, a high-rheological calcium oxide composite emulsion is obtained; The mass ratio of calcium oxide to magnesium oxide is (50-65):(20-35); The dry grinding is adopted in the ball milling, the rotating speed is 240 rpm, and the ball milling time is 2.0-2.5 h; The organic dispersant is a mixture of methyl formate, ethylene glycol and ethyl acetate with a mass ratio of (20-30):(15-25):(5-15); The retarder is a starch solution with a mass fraction of 20%, and the mass ratio of the retarder to calcium oxide is (2-5):(50-65); The amount of water is (400-600) mL, and the amount of calcium oxide is (50-65) g, and the standing time is 0.5-1 h.

2. The method of preparing a high rheology calcium oxide composite emulsion according to claim 1, characterized in that, All the stirring is carried out at 20-40 ℃, and the stirring time is 0.5-1 h.

3. The application of the high-rheological calcium oxide composite emulsion prepared by the preparation method of any one of claims 1-2 in the harmless disposal of phosphogypsum or the treatment of phosphorus and fluorine-containing wastewater.

4. Use according to claim 3, characterized in that, The high-rheological calcium oxide composite emulsion is added into phosphogypsum powder, stirred uniformly, and then stood for 6-24 hours; the amount of the high-rheological calcium oxide composite emulsion is 1% of the mass of the phosphogypsum powder.

5. Use according to claim 3, characterized in that, The high-rheological calcium oxide composite emulsion is added into phosphorus and fluorine-containing wastewater with a phosphate concentration of 50-150 mg / L and a fluorine ion concentration of 50-400 mg / L, and reacted for 0.5-1.5 h; the total mass of CaO and MgO in the high-rheological calcium oxide composite emulsion is 1%-2% of the mass of the phosphorus and fluorine-containing wastewater.

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