Organic high-molecular compound removing agent and preparation method thereof

Abstract

The invention provides an organic high-molecular compound removing agent and a preparation method thereof, and belongs to the technical field of removing agents. The method comprises the following steps: mixing fly ash with sulfuric acid for reaction to obtain pretreated fly ash; then mixing the pretreated fly ash with a sodium aluminate solution for reaction to obtain a fly ash mixture; and finally, activating the fly ash mixture to obtain the organic high-molecular compound removal agent. The removal agent prepared by the method is good in removal performance, and after repeated cyclic regeneration, the removal performance, the iodine adsorption value and the specific surface area of OHPCR are not obviously reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of removers, in particular to an organic polymer compound remover and a preparation method thereof. Background Art

[0002] Fly ash, also known as fly ash, is a tiny ash particle discharged during the combustion of fuel (mainly coal). The particle size is generally between 1 and 100 μm and is a hazardous waste. Fly ash is mainly collected in the coal-to-gas process in alumina production. Since fly ash has a certain specific surface area and loose pore structure, and contains active components such as aluminosilicate, it can enhance the removal effect of impurities after modification.

[0003] At present, more than 90% of alumina production in the world adopts the Bayer process, but this method has a major problem, that is, the mother liquor is repeatedly circulated during the production process, and a large amount of organic matter contained in the original ore will be continuously circulated in the mother liquor, and the carbon atom binding ability of organic compounds is very strong, and they can combine with each other to form carbon chains or carbon rings, and the number of carbon atoms can even reach thousands or tens of thousands, thus forming organic polymer compounds (hereinafter referred to as OHPC). Due to the large molecular weight, it is more difficult to remove it. Especially in recent years, the dependence of my country's aluminum enterprises on imported ores has increased year by year, and the content of organic matter in imported bauxite is relatively high due to the influence of mineral sources, generally between 0.2% and 0.4%, which is 2 to 4 times higher than that of domestic ores. When the type and concentration of organic matter reach a certain level, it will affect the Bayer process of alumina production, resulting in reduced alumina production, particle refinement, increased impurities and reduced chromaticity indicators. And because the mother liquor is repeatedly circulated during the production process, the composition of organic polymer compounds is extremely complex. Therefore, an organic polymer compound remover that can be used in the Bayer process to produce alumina at low cost and high efficiency can increase the popularity of imported ore, thereby alleviating the current situation of tight ore supply.

[0004] For a long time, extensive research has been carried out at home and abroad on the preparation of organic polymer compound removal agents. The main technologies are as follows:

[0005] (1) by loading alkali metal ions, rare earth ions or quasi-rare earth ions on modified dextran;

[0006] (2) preparing a composite of modified carbon nanomaterials and polymerized alumina, and removing organic polymer compounds by utilizing their coagulation properties and nano-effect;

[0007] (3) By modifying coal or wood materials, their complex pores and functional groups are used to remove organic polymer compounds.

[0008] However, some of these methods are technically difficult and require high investment costs, making them difficult to apply industrially. Some of them are not compatible with the Bayer process, increasing operating costs.

[0009] Chinese patent CN202210529803 introduces a method for preparing an organic polymer compound remover, comprising the following steps: ① Primary mixing heating: Mix the carbon material with sucrose, urea, concentrated sulfuric acid and deionized water, heat at 100°C for 6-8h, and then heat to 180°C for 6-8h. ② Secondary mixing heating: Grind the primary mixture and mix it with sucrose, urea, concentrated sulfuric acid and deionized water, heat at 120°C for 6-8h, and then heat to 240°C for 6-8h. ③ Carbonization: Carbonize the secondary mixture at 850°C for 5h in a nitrogen atmosphere, and then cool to room temperature. ④ Pickling and amination modification: Add the carbonized material to the HF solution, filter and wash three times, dry it, and place it in a toluene reagent for 8-10h to increase its specific surface area, and then dry it to obtain an organic polymer compound remover for an aminated mesoporous carbon material. However, this method is complicated, time-consuming, and involves many types of raw materials, which greatly limits its industrial application. Summary of the invention

[0010] In view of this, the present invention provides a method for preparing an organic polymer compound remover, wherein the remover prepared by the method has good removal performance, and the materials used are all materials in the alumina production process and are easy to obtain. Moreover, after multiple cycles of regeneration, the removal performance, iodine adsorption value, and specific surface area of ​​the OHPCR prepared by the method do not show a significant decrease.

[0011] The method for preparing the organic polymer compound removing agent of the present invention comprises the following steps:

[0012] (1) Pretreatment: Sulfuric acid and fly ash are mixed to obtain a mixed solution A, the mixed solution A is stirred, and the mixed solution is filtered and washed with hot water to obtain pretreated fly ash;

[0013] (2) Mixing: mixing the pretreated fly ash with the sodium aluminate solution to obtain a mixed solution B, stirring the mixed solution B, filtering after impregnation, and obtaining a fly ash mixture;

[0014] (3) Activation modification: placing the fly ash mixture in a nitrogen atmosphere, heating it to the activation temperature, introducing water vapor, keeping it warm for a period of time, and then cooling it to room temperature to obtain the organic polymer compound removal agent.

[0015] Preferably, the concentration of sulfuric acid in step (1) is 1.0 to 1.2 mol / L.

[0016] Preferably, the solid content of the mixed solution A in step (1) is 300-320 g / L.

[0017] Preferably, the stirring temperature in step (1) is 90-100° C., and the stirring time is 2-2.5 h.

[0018] Preferably, the sodium aluminate solution in step (2) includes components with the following concentrations:

[0019] NaOH 190~200g / L, Al2O390~100g / L.

[0020] Preferably, the concentration of pretreated fly ash in the mixed liquor B in step (2) is 200 g / L.

[0021] Preferably, the stirring temperature in step (2) is 50-65° C., and the stirring time is 2-4 h.

[0022] Preferably, the activation modification step in step (3) is as follows: placing the fly ash mixture in a nitrogen atmosphere, heating it to 800-850°C at a rate of 15°C / min, introducing 80-120L / h of water vapor, keeping the temperature for 60-70 minutes, and then cooling it to room temperature.

[0023] Another object of the present invention is to provide an organic polymer compound removing agent prepared by the above method.

[0024] The present invention also provides a method for regenerating the above-mentioned organic polymer compound removing agent, comprising the following steps:

[0025] The used organic polymer compound removing agent is placed in a nitrogen atmosphere, heated to 600-650°C at a rate of 15°C / min, 80-120L / h of water vapor is introduced, and after keeping warm for 60 minutes, it is cooled to room temperature to obtain a regenerated organic polymer compound removing agent.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention uses sodium aluminate (NaAlO2) solution to impregnate fly ash, and then modifies it at high temperature. + The intercalation ability forms a complex pore structure, while the inner wall of the pore is modified with AlO2 - ions, using AlO2 - The function of exchanging ions with carbon chain anions strengthens the removal ability of the remover, and the filtered sodium aluminate solution can be returned to the production system for reuse. The remover prepared by the present invention can be regenerated and recycled, and the various organic polymer impurities removed by it are partially in the form of sodium salts, which can be pyrolyzed into sodium oxide during the regeneration and modification process, and most of the remaining impurities can be pyrolyzed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1The present invention is a flow chart of the preparation and regeneration method of the organic polymer compound removing agent. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing an organic polymer compound removing agent, the steps of which are as follows:

[0030] (1) Pretreatment: Sulfuric acid and fly ash are mixed in a stirring tank 1 to obtain a mixed solution A, the mixed solution A is stirred, filtered through a filter press 1 and washed with hot water to obtain a filter cake 1 as pretreated fly ash;

[0031] (2) Mixing: pretreated fly ash and sodium aluminate solution are mixed in a stirring tank 2 to obtain a mixed solution B, the mixed solution B is stirred, and after impregnation, it is filtered using a filter press 2 to obtain a filter cake 2 as a fly ash mixture;

[0032] (3) Activation modification: The fly ash mixture is placed in a rotary kiln in a nitrogen atmosphere, steam is introduced after the temperature is increased, and the mixture is cooled to room temperature after being kept warm to obtain the organic polymer compound removing agent.

[0033] In a specific embodiment of the present invention, the concentration of sulfuric acid in step (1) is 1.0-1.2 mol / L.

[0034] In a specific embodiment of the present invention, the solid content of the mixed solution A in step (1) is 300-320 g / L.

[0035] In a specific embodiment of the present invention, the stirring temperature in step (1) is 90-100° C., and the stirring time is 2-2.5 h.

[0036] In a specific embodiment of the present invention, the sodium aluminate solution in step (2) includes components with the following concentrations:

[0037] NaOH 190~200g / L, Al2O390~100g / L.

[0038] In a specific embodiment of the present invention, the concentration of pretreated fly ash in the mixed liquor B in step (2) is 200 g / L.

[0039] In a specific embodiment of the present invention, the stirring temperature in step (2) is 50-65° C., and the stirring time is 2-4 hours.

[0040] In a specific embodiment of the present invention, the activation modification step of step (3) is as follows: placing the fly ash mixture in a nitrogen atmosphere, heating it to 800-850°C at a rate of 15°C / min, introducing 80L / h of water vapor, keeping the temperature for 60-70 minutes, and then cooling it to room temperature.

[0041] After the organic polymer compound removing agent prepared by the present invention is used to treat the evaporation mother liquor in the removal tank, it is filtered in the filter press 3 to obtain the filter cake 3, which is the OHPCR after the evaporation mother liquor is treated; the OHPCR after the evaporation mother liquor is treated is then placed in a rotary kiln, and 80L / h of water vapor is introduced after heating, and then cooled to room temperature after insulation to obtain the regenerated OHPCR, and then the regenerated OHPCR can be used again to treat the evaporation mother liquor.

[0042] The flow chart of the organic polymer compound removing agent and the preparation and regeneration method thereof of the present invention is as follows Figure 1 .

[0043] The present invention will be further described below in conjunction with the embodiments.

[0044] Example 1

[0045] A method for preparing an organic polymer compound removing agent, comprising the following steps:

[0046] (1) Pretreatment: Sulfuric acid with a concentration of 1.0 mol / L was mixed with fly ash to obtain a mixed solution A, which was stirred at 90° C. for 2 h, and then filtered and washed with hot water (80° C.) to obtain pretreated fly ash; wherein the solid content of the mixed solution A was 300 g / L;

[0047] (2) Mixing: The pretreated fly ash was mixed with sodium aluminate solution (NaOH 190 g / L, Al2O3 100 g / L, the same below) to obtain a mixed solution B, which was stirred at 60°C for 4 h, filtered after immersion, and a fly ash mixture was obtained, wherein the solid content of the mixed solution B was 200 g / L.

[0048] (3) Activation modification: placing the fly ash mixture in a nitrogen atmosphere, heating it to 800°C at a rate of 15°C / min, introducing 80L / h of water vapor, keeping the temperature for 60min, and then cooling it to room temperature to obtain the organic polymer compound removal agent (OHPCR);

[0049] The sodium aluminate solution recovered after filtration in the above step can be returned to the production system for reuse.

[0050] The particle size distribution and physical properties of the fly ash used in the present invention are shown in Table 1.

[0051] Table 1

[0052]

[0053] The composition (%) of fly ash is shown in Table 2.

[0054] Table 2

[0055] Element Fixed Carbon Ash Volatile Matter Analyzing water content 71.63 25.01 2.84 0.52

[0056] The chemical composition (%) of fly ash is shown in Table 3.

[0057] Table 3

[0058] <![CDATA[Na2O]]> MgO <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[P2O5]]> <![CDATA[SO3]]> <![CDATA[K2O]]> 1.45 1.26 17.49 42.56 0.29 7.08 0.51 CaO <![CDATA[TiO2]]> MnO <![CDATA[Fe2O3]]> BaO <![CDATA[V2O5]]> 10.74 0.82 0.40 16.91 0.24 0.11

[0059] The specific components of the evaporation mother liquor are shown in Table 4.

[0060] Table 4

[0061] chemical composition NaOH <![CDATA[Al2O3]]> <![CDATA[CH3COO - ]]> <![CDATA[Na2CO3]]> <![CDATA[C2O4 2- ]]> OHPC <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> Concentration g / L 251.08 116.11 14.76 6.71 1.62 2.36 0.68 0.70

[0062] The organic polymer compound remover prepared by the present invention is used to treat the evaporated mother liquor in a removal tank, and the treatment conditions are: OHPCR addition amount is 5 g / L, temperature is 60° C., and reaction time is 4 hours.

[0063] By changing the amount of pretreated fly ash and sodium aluminate solution in step (2), different removing agents were prepared to treat the evaporation mother liquor. The removing agent was washed with deionized water to neutrality and then fully dried at 60°C to measure the iodine adsorption value and specific surface area. The results are shown in Table 5.

[0064] Table 5

[0065] Sodium aluminate solution volume g / L 100 200 300 400 Iodine adsorption value / (mg / g) 635 694 663 616 <![CDATA[Specific surface area m 2 / g]]> 532 567 547 509 OHPC removal rate / % 53.15 61.35 56.14 52.11

[0066] Table 5 shows that the optimal amount of sodium aluminate solution is 200 g / L. When the amount of sodium aluminate solution is 200 g / L, the OHPC removal rate is 64% and the original fly ash removal rate is 6.24% when the evaporation mother liquor is treated with the remover.

[0067] The fly ash mixture and OHPCR obtained under the optimal conditions were washed with deionized water until neutral, and then the liquid phase and solid phase were analyzed. The components (%) are shown in Table 6 (on a dry basis).

[0068] Table 6

[0069]

[0070]

[0071] From the above table, we can see that after fly ash is mixed with sodium aluminate solution, NaOH and Al2O3 will be attached, which will play an activating role in the activation process. At the same time, after activation, the loss of NaOH and Al2O3 is small.

[0072] The tail gas components (V%) generated during the activation and modification process in Example 1 are shown in Table 7.

[0073] Table 7

[0074] Element <![CDATA[N2]]> CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[CH4]]> <![CDATA[O2]]> <![CDATA[Calorific value kcal / m 3 > V％ 37.07 43.00 4.60 6.93 7.80 0.40 1660

[0075] It can be seen from Table 7 that the combustible gas content in the tail gas is high and the calorific value is high, so it can be sent to the roasting furnace as fuel gas to save the cost of tail gas treatment.

[0076] Example 2

[0077] The OHPCR after the mother liquor is evaporated in Example 1 is regenerated, and the specific steps of regeneration are as follows:

[0078] The OHPCR after treating the evaporated mother liquor (i.e. before regeneration) was placed in a rotary kiln in a nitrogen atmosphere, heated to 600°C at a rate of 15°C / min, and 80L / h of water vapor was introduced. After keeping the temperature for 60 minutes, it was cooled to room temperature to obtain the regenerated OHPCR (i.e. after regeneration). The remover before and after regeneration was washed with deionized water to neutrality, filtered, and the liquid phase and solid phase were analyzed. The composition (%, on a dry basis) is shown in Table 8.

[0079] Table 8

[0080] name Fly ash OHPC NaOH <![CDATA[Al2O3]]> Sodium Oxalate other Before regeneration 57.40 3.10 8.41 6.39 16.14 8.56 After regeneration 66.40 0.17 6.31 7.74 0.05 19.33

[0081] It can be seen from the above table that after the OHPCR treatment and evaporation of the mother liquor, impurities such as OHPC and sodium oxalate will be attached. After high-temperature regeneration, most of the impurities are pyrolyzed and will not be brought into the production system when reused, thus meeting the conditions for regeneration.

[0082] By changing the number of regeneration times and adding corresponding pretreated fly ash during activation modification according to the change in fly ash mass before and after activation, the above operations were repeated. The performance of different regenerated OHPCR and OHPC removal rate were shown in Table 9.

[0083] Table 9

[0084] Regeneration times Fly ash mass loss rate % OHPC removal rate % Iodine adsorption value mg / g <![CDATA[Specific surface area m 2 / g]]> 0 16.15 61.16 694 567 1 22.31 56.23 645 522 2 29.75 50.14 584 433 3 35.61 42.86 540 405

[0085] It can be seen from Table 9 that after multiple cycles of regeneration, the removal performance, iodine adsorption value and specific surface area of ​​OHPCR did not show a significant decrease. However, it should be noted that during the regeneration process, the mass loss of fly ash will occur. Before the rotary kiln activation modification, the pretreated fly ash should be appropriately supplemented according to the corresponding mass loss to ensure stable production.

[0086] Comparative Example 1

[0087] A method for preparing an organic polymer compound removing agent, comprising the following steps:

[0088] (1) Mixing: Fly ash and sodium aluminate solution were mixed and stirred at an ash amount of 200 g / L and a temperature of 60°C. The mixture was reacted for 4 h and filtered after being fully mixed.

[0089] (2) Activation modification: The filtered mixture was placed in a nitrogen atmosphere, and the activation conditions were a heating rate of 15°C / min, a temperature of 800°C, 80L / h of water vapor, and heat preservation for 60 minutes, and cooled to room temperature to obtain OHPCR. The composition and physical properties of the obtained OHPCR are shown in Table 10 (the analysis method is the same as above).

[0090] Table 10

[0091]

[0092] The OHPC was used to treat the evaporation mother liquor (same as in Example 1), and the OHPC removal rate was 51%, and the original fly ash removal rate was 7.03%.

[0093] Comparative Example 2

[0094] A method for preparing an organic polymer compound removing agent, comprising the following steps:

[0095] (1) Pretreatment: Sulfuric acid and fly ash were mixed and stirred, wherein the concentration of sulfuric acid was 1.0 mol / L, the solid content was 300 g / L, the temperature was 90°C, stirred for reaction for 2 h, and then filtered and washed;

[0096] (2) Activation modification: The filtered pretreated fly ash was heated to 800 °C at a rate of 15 °C / min in a nitrogen atmosphere, 80 L / h of water vapor was introduced, and the mixture was kept warm for 60 min and then cooled to room temperature to obtain OHPCR.

[0097] The physical properties of the OHPCR are as follows: iodine adsorption value 487 mg / g, specific surface area 367 m 2 / g.

[0098] The OHPC was used to treat the evaporation mother liquor (same as in Example 1), and the OHPC removal rate was 39%, and the original fly ash removal rate was 6.76%.

Claims

1. A method for preparing an organic polymer compound removing agent, characterized in that: The following steps are involved: (1) Pretreatment: Sulfuric acid and fly ash are mixed to obtain a mixed solution A, the mixed solution A is stirred, and the mixed solution is filtered and washed with hot water to obtain pretreated fly ash; (2) Mixing: mixing the pretreated fly ash with the sodium aluminate solution to obtain a mixed solution B, stirring the mixed solution B, filtering after impregnation, and obtaining a fly ash mixture; (3) Activation modification: placing the fly ash mixture in a nitrogen atmosphere, heating it to the activation temperature, introducing water vapor, keeping it warm for a period of time, and then cooling it to room temperature to obtain the organic polymer compound removal agent.

2. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The concentration of sulfuric acid in step (1) is 1.0-1.2 mol / L.

3. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The solid content of the mixed solution A in step (1) is 300-320 g / L.

4. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The stirring temperature in step (1) is 90-100° C. and the stirring time is 2-2.5 h.

5. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The sodium aluminate solution in step (2) includes components having the following concentrations: NaOH 190~200g / L, Al2O390~100g / L.

6. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The concentration of pretreated fly ash in the mixed solution B in step (2) is 200 g / L.

7. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The stirring temperature in step (2) is 50-65° C. and the stirring time is 2-4 hours.

8. The method for preparing the organic polymer compound removing agent according to claim 1, characterized in that: The activation modification step in step (3) is as follows: placing the fly ash mixture in a nitrogen atmosphere, heating it to 800-850°C at a rate of 15°C / min, introducing 80-120L / h of water vapor, keeping the temperature for 60-70 minutes, and then cooling it to room temperature.

9. An organic polymer compound removing agent, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. The method for regenerating the organic polymer compound removing agent according to claim 9, comprising the following steps: The used organic polymer compound removing agent is placed in a nitrogen atmosphere, heated to 600-650°C at a rate of 15°C / min, 80-120L / h of water vapor is introduced, and after keeping warm for 60 minutes, it is cooled to room temperature to obtain a regenerated organic polymer compound removing agent.

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