A method for preparing high value-added calcium carbonate by solidifying carbon dioxide with waste incineration fly ash water washing solution

Abstract

The application discloses a method for preparing high-value-added calcium carbonate by solidifying carbon dioxide by using waste incineration fly ash water washing liquid, which comprises the following steps: obtaining a water washing liquid by water washing of waste incineration fly ash; mixing the water washing liquid with ammonia water and a morphology control agent under the action of ultrasonic waves; introducing a gas containing carbon dioxide to carry out a solidification reaction; and carrying out solid-liquid separation to obtain a vaterite type calcium carbonate and a high-salt solution. The method realizes resource utilization and harmless treatment of the waste incineration fly ash water washing liquid, realizes carbon dioxide solidification and co-production of high-value-added vaterite type calcium carbonate products, and forms a comprehensive route for comprehensive utilization of waste incineration fly ash water washing liquid solid waste and carbon dioxide solidification and utilization.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for treating waste incineration fly ash washing liquid, in particular to a method for preparing vaterite type calcium carbonate by using waste incineration fly ash washing liquid to solidify carbon dioxide, belonging to the technical field of solid waste resource utilization. BACKGROUND

[0002] Waste incineration fly ash is produced in the process of municipal solid waste incineration, which is derived from limestone, lime, etc. added in the flue gas purification process. They are captured together in electrostatic precipitator, bag filter and other devices, and a part of fine particles also settle down at the bottom of the flue and chimney. Waste incineration fly ash contains a large amount of calcium oxide, calcium hydroxide, basic calcium chloride and other calcium-containing minerals, which are potential resources and have high carbon sequestration potential.

[0003] In the existing CCUS technology, it is necessary to use high calcium and magnesium solid waste to fix carbon dioxide. Using waste incineration fly ash to fix carbon dioxide can also solve the problem of resource utilization. Chinese patent (CN114888056A) discloses that a certain flow of carbon dioxide is introduced into the first-stage washing process of waste incineration fly ash three-stage countercurrent water washing, so as to realize the fixation of carbon dioxide and deep dechlorination, but there are problems such as difficulty in separating carbonate products, low product added value, etc. In addition, when waste incineration fly ash is leached by wet method and the washing residue is reused, the problem of high-salt wastewater purification must be faced. Therefore, it is of high economic and social benefits to develop a process that can not only purify waste incineration washing liquid, but also improve the carbon sequestration efficiency of waste incineration fly ash washing liquid, increase the purity of carbon sequestration products and increase the added value of products. SUMMARY

[0004] In view of the above problems existing in the prior art, the purpose of the present application is to provide a method for preparing high added value calcium carbonate by using waste incineration fly ash washing liquid to solidify carbon dioxide. This method can efficiently realize the resource utilization of waste incineration fly ash washing liquid. Not only can all the calcium ions in the waste incineration fly ash washing liquid be converted into high added value vaterite type calcium carbonate, but also soluble potassium salt, sodium salt, etc. can be separated and recovered. At the same time, carbon dioxide in industrial carbon dioxide flue gas can be efficiently fixed. In addition, water can be recycled in the whole process, reducing water consumption.

[0005] In order to achieve the above technical purpose, the present application provides a method for preparing high added value calcium carbonate by using waste incineration fly ash washing liquid to solidify carbon dioxide. The method is to wash waste incineration fly ash to obtain washing liquid, mix the washing liquid with ammonia and morphology control agent under the action of ultrasonic, and introduce carbon dioxide-containing gas for solidification reaction, then separate the solid and liquid to obtain vaterite type calcium carbonate and high salt solution.

[0006] The key of the technical scheme of the present application is to realize the resource utilization of the waste incineration fly ash water washing liquid. On one hand, the calcium ions in the waste incineration fly ash water washing liquid are used to fix carbon dioxide, thereby solving the technical problem of high carbon emission in industry, and by controlling the reaction conditions, the ball spar type calcium carbonate with high value can be obtained. On the other hand, the chloride salt in the waste incineration fly ash water washing liquid is also recovered, and the water can be recycled, which is conducive to environmental protection and cost reduction. In addition, by using the ultrasonic field cavitation effect and using a morphology control agent, the dispersibility of the generated calcium carbonate can be effectively improved, and the particle agglomeration is inhibited, which is more conducive to the generation of ball spar type calcium carbonate ultrafine powder.

[0007] As a preferred scheme, the morphology control agent comprises a surface modifier and a morphology inducer.

[0008] As a preferred scheme, the surface modifier comprises at least one of condensed phosphoric acid, fatty acid (the number of carbon atoms is generally 12-16), fatty acid salt (the number of carbon atoms is generally 12-16), titanate coupling agent, aluminate coupling agent, phosphate ester, and biological macromolecule. The condensed phosphoric acid can be metaphosphoric acid or pyrophosphoric acid. The fatty acid salt is at least one of ammonium fatty acid, sodium stearate, and potassium stearate. The titanate coupling agent can be triisostearyl titanate isopropyl (TTS). The aluminate coupling agent can be di-stearoyl oxygen isopropyl aluminate. The phosphate ester is an ester derivative of phosphoric acid, which belongs to a class of phosphate ester derivatives, and can be a phosphoric acid triester. The biological macromolecule can be at least one of chitin, mannose protein, and other polysaccharide protein complexes. The surface modifier of the present application can modify the surface of the ball spar type calcium carbonate generated by the solidification reaction, reduce the surface energy, and endow the surface with lipophilic and hydrophobic properties, so as to reduce the mixing unevenness and agglomeration, and improve the interfacial compatibility with the ball spar type calcium carbonate. The morphology inducer comprises a low-carbon alcohol, such as an alcohol with a carbon atom number of not more than 5, specifically ethanol. The morphology inducer plays a role in inducing and adjusting the morphology, which is conducive to the formation of ball spar type calcium carbonate particles with regular morphology.

[0009] As a preferred scheme, the mass of the surface modifier is 0.5-5% of the mass of the water washing liquid.

[0010] As a preferred scheme, the volume of the morphology inducer is 5-25% of the volume of the water washing liquid. The addition of an appropriate amount of surface modifier and morphology inducer has an inducing effect on the morphology of calcium carbonate crystals, which converts the calcium carbonate crystal type to ball spar, and the ethanol in water can make the ball spar type calcium carbonate exist stably. If the surface modifier and the morphology inducer are added in excess, the calcium carbonate crystal type and the morphology are not greatly affected, and the excessive addition will increase the consumption of reagents.

[0011] As a preferred scheme, the amount of ammonia water added is more than 2 times the molar amount of calcium ions in the water washing solution. The mass concentration of ammonia water is 25-28%. The theoretical value of ammonia water added is 2 times the molar amount of calcium ions, and appropriate excess of ammonia water is conducive to the complete conversion of calcium ions, but ammonia water is not the higher the better, and the excessive ammonia water is completely converted into ammonium salt, which will increase the use cost of ammonia water.

[0012] As a preferred scheme, the carbon dioxide-containing gas is dispersed into the water washing solution by a nanobubble disperser, and the bubble size is 10-500 nm. In the technical scheme of the present application, the carbon dioxide-containing gas is dispersed by a nanobubble disperser, and under the homogenization effect of ultrasonic, the carbon dioxide bubbles are dispersed into smaller and more uniform bubbles, which can accelerate the carbon dioxide solidification efficiency and is conducive to obtaining high-purity vaterite-type calcium carbonate.

[0013] As a preferred scheme, the solidification reaction conditions are as follows: the ultrasonic power is 500-2000 W, the reaction temperature is 20-40℃, the flow rate of the carbon dioxide-containing gas is 0.3-3 L / min, the reaction time is 10-30 min, and the volume concentration of the carbon dioxide-containing gas is not less than 5%. The higher the ultrasonic power, the more conducive to controlling the morphology and particle size of the vaterite-type calcium carbonate and reducing the agglomeration of the vaterite-type calcium carbonate, but if the ultrasonic power exceeds 2000 W, the effect is no longer obvious, and the energy consumption is large. The greater the flow rate of the carbon dioxide, the more conducive to improving the carbon dioxide solidification efficiency, but too high a flow rate of the carbon dioxide will affect the generation of the vaterite-type calcium carbonate. Within the preferred reaction temperature range, the higher the reaction temperature, the less the amount of vaterite-type calcium carbonate, and when the reaction temperature is 20℃, the content of the vaterite-type calcium carbonate is the highest, and when the temperature is greater than 40℃, the content of the vaterite-type calcium carbonate is less.

[0014] As a preferred scheme, the carbon dioxide-containing gas is derived from the calcination of carbonate minerals, the combustion of fossil fuels, smelting flue gas or waste incineration flue gas. The carbonate minerals are limestone, magnesite, dolomite, etc. The fossil fuels are coal, petroleum, natural gas, etc. The smelting flue gas is steel smelting flue gas, non-ferrous metal smelting flue gas.

[0015] As a preferred scheme, the water washing adopts a three-stage countercurrent water washing mode; the water washing solution obtained by the third-stage countercurrent water washing is recycled to the second-stage countercurrent water washing process, the water washing solution obtained by the second-stage countercurrent water washing is recycled to the first-stage countercurrent water washing process, and the water washing solution obtained by the first-stage countercurrent water washing is used for the solidification reaction. The use of the multi-stage countercurrent water washing mode can not only improve the dissolution efficiency of the soluble salts in the waste incineration fly ash, but also reduce the amount of washing water, improve the enrichment rate of the soluble salts, and increase the salt concentration in the water washing solution.

[0016] As a preferred scheme, the liquid-solid ratio of each stage of countercurrent water washing is 2-5 L:1 kg.

[0017] As a preferred scheme, the conditions of each stage of countercurrent water washing are as follows: stirring leaching at a speed of 500-1000 r / min at normal temperature for 30-90 min.

[0018] The high-salt solution of the present application is evaporated to obtain a chlorate product, and the water recovered in the evaporation process is recycled in the water washing process.

[0019] The solid-liquid separation of the solidification reaction product of the present application obtains vaterite-type calcium carbonate and a high-salt solution, the vaterite-type calcium carbonate is washed and dried (at a temperature of 60-100 DEG C for 1-5 h), the high-salt solution is evaporated appropriately to obtain a chlorate product, and the evaporated water is recycled.

[0020] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0021] (1) The present application can utilize the calcium ions in the waste incineration fly ash water washing solution to solidify carbon dioxide, reduce the emission of carbon dioxide in flue gas, reduce the cost of carbon dioxide fixation, and fully utilize the soluble calcium salt in the waste incineration fly ash to react with carbon dioxide to convert carbon dioxide into stable carbonates, thereby improving the solidification efficiency of carbon dioxide.

[0022] (2) The present application disperses carbon dioxide bubbles into nanobubbles in the solution by passing the carbon dioxide-containing flue gas through a nanobubble disperser, thereby improving the carbon dioxide solidification rate in the solution and being beneficial to the formation of vaterite-type calcium carbonate.

[0023] (3) The present application utilizes the ultrasonic field and the introduction of a morphology-controlling agent to inhibit the agglomeration and growth of calcium ions in the water washing solution in the waste incineration fly ash into ultra-fine particle calcium carbonate, which is beneficial to obtaining high-value-added vaterite-type calcium carbonate ultra-fine powder.

[0024] (4) The high-salt solution contains a large amount of sodium chloride, potassium chloride and ammonium chloride, which can be recovered by evaporation to increase economic benefits.

[0025] (5) The water solution after salting of the high-salt solution of the present application can be recycled to the three-stage countercurrent water washing process, thereby reducing water resource consumption and reducing reagent consumption cost.

[0026] In summary, the present application solves the problem of purification of waste incineration fly ash washing liquid, solidifies carbon dioxide in flue gas and produces high value-added ball-shaped calcite type calcium carbonate powder, the ball-shaped calcite type calcium carbonate has the characteristics of high purity, uniform particle size and the like; in addition, the components of ammonium chloride, sodium chloride and potassium chloride in the high-salt solution can be separated and purified, and high-purity chlorides are obtained. The filtrate after separation and purification can be recycled, reducing the consumption of water resources. Therefore, the present application realizes carbon dioxide solidification, carbonate product value-added, and water resource recycling, and has good social, environmental and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a process flow chart of the present application.

[0028] Figure 2 is a micro-morphology chart under different embodiments.

[0029] Figure 3 is a phase diagram under different embodiments.

[0030] Figure 4 is a micro-morphology chart of calcium carbonate after carbon dioxide solidification by conventional water bath and ultrasonic field.

[0031] Figure 5 is a micro-morphology comparison chart of calcium carbonate products without adding modifier and adding 0.5% of metaphosphoric acid. DETAILED DESCRIPTION

[0032] In order to better explain the present application, the content of the present application is described in detail by specific embodiments in combination with the drawings, but the following embodiments do not limit the scope of protection of claims.

[0033] In the following examples, if no special instructions are given, the chemical reagents used are commercial reagents.

[0034] Example 1

[0035] Take 1 kg of fly ash from a waste incineration power plant in Hunan Province, dissolve it in water according to the liquid-solid ratio of 4 L: 1 kg for three-stage countercurrent water washing, the water washing solution obtained by the third-stage countercurrent water washing is recycled to the second-stage countercurrent water washing process, and the water washing solution obtained by the second-stage countercurrent water washing is recycled to the first-stage countercurrent water washing process; the water washing process parameters are: the water washing stirring rate is 500 r / min, the stirring time is 30 min, the calcium ion concentration in the first-stage water washing solution is 0.32 mol / L, the chloride ion concentration is 1.04 mol / L, the potassium ion concentration is 0.20 mol / L, and the sodium ion concentration is 0.61 mol / L. Take 1 L of the first-stage water washing solution and add 98.46 mL of ammonia solution (25% mass percentage concentration), 5 vol.% of ethanol and 0.5 wt.% of metaphosphoric acid, and place it in an ultrasonic field (ultrasonic power 500 W). Disperse the carbon dioxide volume fraction of 5% flue gas into bubbles with an average particle size of 500 nm by gas disc stone and blow into the solution for reaction. The carbon dioxide solidification process is: the flue gas flow rate is 0.3 L / min, the reaction temperature is 40℃, the ultrasonic power is 500 W, and the reaction time is 10 min. After the solid-liquid separation, the solid product is dried at 60℃ for 5 h to obtain the vaterite-type calcium carbonate product. The liquid phase product is a high-salt solution, which is evaporated step by step to obtain ammonium chloride, sodium chloride and potassium chloride products in turn, and the drying temperature is 100℃ and the drying time is 5 h. The final vaterite-type calcium carbonate content is 86%, the ammonium chloride purity is 91%, the sodium chloride purity is 96%, and the potassium chloride purity is 97%.

[0036] Example 2

[0037] Take 1 kg of fly ash from a waste incineration power plant in Guangdong Province, dissolve it in water according to the liquid-solid ratio of 2 L: 1 kg for three-stage countercurrent water washing, the water washing liquid obtained in the third-stage countercurrent water washing is recycled to the second-stage countercurrent water washing process, and the water washing liquid obtained in the second-stage countercurrent water washing is recycled to the first-stage countercurrent water washing process; the water washing process parameters are: the water washing stirring rate is 800 r / min, the stirring time is 60 min, the calcium ion concentration in the first-stage water washing liquid is 0.44 mol / L, the chloride ion concentration is 1.42 mol / L, the potassium ion concentration is 0.31 mol / L, and the sodium ion concentration is 0.55 mol / L. Take 1 L of the first-stage water washing liquid and add 59.23 mL of ammonia water solution (mass percentage concentration of 26%), 10 vol.% of ethanol, and 0.5 wt.% of pyrophosphoric acid, and place it in an ultrasonic field (power of 1500 W), disperse the flue gas with a carbon dioxide volume fraction of 25% into bubbles with an average particle size of 50 nm by a gas disc stone and blow it into the solution for reaction, the carbon dioxide solidification process is: the flue gas flow rate is 1.5 L / min, the reaction temperature is 30°C, the ultrasonic power is 1500 W, and the reaction time is 20 min. After the solidification reaction is completed, the solid-liquid is separated, and the solid product is dried at 80°C for 2 h to obtain a vaterite-type calcium carbonate product. The liquid phase product is a high-salt solution, which is evaporated step by step in three stages to obtain ammonium chloride, sodium chloride, and potassium chloride products, respectively, with a drying temperature of 110°C and a drying time of 2 h. The final vaterite-type calcium carbonate content is 90%, the ammonium chloride purity is 94%, the sodium chloride purity is 97%, and the potassium chloride purity is 98%.

[0038] Example 3

[0039] Take 1 kg of fly ash from a waste incineration power plant in Shanghai, dissolve it in water according to the liquid-solid ratio of 5 L: 1 kg for three-stage countercurrent water washing, the water washing liquid obtained in the third-stage countercurrent water washing is recycled to the second-stage countercurrent water washing process, and the water washing liquid obtained in the second-stage countercurrent water washing is recycled to the first-stage countercurrent water washing process; the water washing process parameters are: the water washing stirring rate is 1000 r / min, the stirring time is 90 min, the calcium ion concentration in the first-stage water washing liquid is 0.25 mol / L, the chloride ion concentration is 1.13 mol / L, the potassium ion concentration is 0.18 mol / L, and the sodium ion concentration is 0.55 mol / L. Take 1 L of the first-stage water washing liquid and add 31.25 mL of ammonia water solution (mass percentage concentration of 28%), 25 vol.% of ethanol, and 0.5 wt.% of sodium stearate (NaCH3(CH2) 16COO) and placed in an ultrasonic field (power 2000 W), pure carbon dioxide was dispersed into bubbles with an average particle size of 10 nm by a gas disc stone and blown into the solution for reaction, and the carbon dioxide solidification process was: carbon dioxide flow rate was 3 L / min, reaction temperature was 20℃, ultrasonic power was 2000 W, and reaction time was 30 min. After the solidification reaction, the solid-liquid was separated, and the solid product was dried at 100℃ for 1 h to obtain the vaterite type calcium carbonate product. The liquid phase product was a high salt solution, which was evaporated by three stages to obtain ammonium chloride, sodium chloride and potassium chloride products in turn, the drying temperature was 125℃, and the drying time was 1 h. The final vaterite type calcium carbonate content was 95%, the ammonium chloride purity was 92%, the sodium chloride purity was 97%, and the potassium chloride purity was 96%.

[0040] Comparative Example 1

[0041] Compared with Example 1, the difference is that: in the solidification reaction process, neither ultrasonic field is used, but conventional stirring is used, the stirring rate is 900 r / min, and the reaction generates calcite type calcium carbonate, as shown in Figure 4 .

[0042] Comparative Example 2

[0043] Compared with Example 1, the difference is that: in the solidification reaction process, the washing liquid does not add metaphosphoric acid and ethanol as a morphology control agent, as shown in Figure 5 , the prepared vaterite type calcium carbonate particles have obvious agglomeration phenomenon. And Figure 5 , the right graph is added metaphosphoric acid and ethanol as a morphology control agent, which shows that the morphology control agent can obviously reduce the surface energy of the vaterite particles, which is beneficial to reduce the agglomeration of the vaterite type calcium carbonate particles.

Claims

1. A method for preparing high value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washings, characterized in that: The waste incineration fly ash is washed with water to obtain a washing liquid, which is then mixed with ammonia water and a morphology control agent under ultrasonic action, and a carbon dioxide-containing gas is introduced to perform a solidification reaction, followed by solid-liquid separation to obtain vaterite-type calcium carbonate and a high-salt solution; The morphology regulating agent comprises a surface modifier and a morphology inducing agent; The surface modifier includes at least one of metaphosphoric acid, pyrophosphoric acid, and sodium stearate; The morphology inducing agent includes ethanol; The curing reaction conditions are as follows: ultrasonic power of 500-2000 W, reaction temperature of 20-40° C., flow rate of carbon dioxide-containing gas of 0.3-3 L / min, reaction time of 10-30 min, and volume concentration of carbon dioxide-containing gas of not less than 5%.

2. The method for preparing high value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washing liquid according to claim 1, characterized in that: The mass of the surface modifier is 0.5-5% of the mass of the water washing liquid; The volume of the morphology inducing agent is 5-25% of the volume of the water washing solution.

3. The method for preparing high value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washing liquid according to claim 1, characterized in that: The amount of ammonia water added is more than twice the molar amount of calcium ions in the water washing solution.

4. The method for preparing high-value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washings according to claim 1, characterized in that: The carbon dioxide-containing gas is exploded into the water wash liquid by a nano bubble disperser, and the bubble size is 10-500 nm.

5. The method for preparing high value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washing liquid according to claim 4, characterized in that: The carbon dioxide-containing gas originates from the calcination of carbonate minerals, combustion of fossil fuels, smelting flue gas or waste incineration flue gas.

6. The method for preparing high value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washing liquid according to claim 1, characterized in that: The water washing adopts a three-stage countercurrent water washing method; The washing liquid obtained from the third-stage countercurrent washing is circulated to the second-stage countercurrent washing process, and the washing liquid obtained from the second-stage countercurrent washing is circulated to the first-stage countercurrent washing process; The washing liquid obtained from the first stage countercurrent washing is used for the solidification reaction.

7. The method for preparing high-value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washings according to claim 6, characterized in that: The liquid-to-solid ratio of each level of countercurrent washing is 2~5 L:1 kg.

8. The method for preparing high-value-added calcium carbonate by solidifying carbon dioxide from waste incineration fly ash washings according to claim 6, characterized in that: The conditions for each level of countercurrent washing are: stirring and leaching for 30 to 90 minutes at a rate of 500 to 1000 r / min under normal temperature conditions.

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