阅读说明：本技术 一种生活垃圾焚烧飞灰中二噁英的浮选脱除及降解方法 (Flotation removal and degradation method for dioxin in household garbage incineration fly ash ) 是由 许李 任凌伟 叶珍 刘建磊 于 2021-08-12 设计创作，主要内容包括：本发明公开了一种生活垃圾焚烧飞灰中二噁英的浮选脱除及降解方法。该方法步骤如下：一、将飞灰与水按质量比1:5～1:10制浆,得到水灰浆。二、将盐酸加入到水灰浆中进行调浆；三、对高钙水灰浆进行浮选。四、对浮选液进行蒸发结晶回收氯化钙；对浮选泡沫进行漂洗、脱水和干燥,得到炭渣。五、对炭渣进行低温等离子体反应器与光催化剂耦合处理。本发明利用飞灰本身高氯盐及氧化钙含量高的特性,加入盐酸调浆进一步增强灰浆盐浓度及二价钙离子溶解量,使灰浆中离子电荷提高,达到抑制气泡聚结程度,提高泡沫稳定性的效果；从而在不添加起泡剂的情况下,保证了浮选过程中气泡效果,提高飞灰残炭捕集率。(The invention discloses a method for removing and degrading dioxin in household garbage incineration fly ash by flotation. The method comprises the following steps: firstly, the fly ash and water are pulped according to the mass ratio of 1: 5-1: 10 to obtain water mortar. Secondly, adding hydrochloric acid into the water-based mortar for size mixing; and thirdly, carrying out flotation on the high-calcium water lime slurry. Fourthly, evaporating and crystallizing the flotation solution to recover calcium chloride; and rinsing, dehydrating and drying the flotation foam to obtain carbon residue. Fifthly, coupling treatment of the low-temperature plasma reactor and the photocatalyst is carried out on the carbon slag. According to the invention, by utilizing the characteristics of high content of high chloride salt and calcium oxide in the fly ash, hydrochloric acid is added for size mixing to further enhance the salt concentration of mortar and the dissolution amount of divalent calcium ions, so that the ionic charge in mortar is improved, and the effects of inhibiting the coalescence degree of air bubbles and improving the foam stability are achieved; therefore, under the condition of not adding a foaming agent, the bubble effect in the flotation process is ensured, and the fly ash carbon residue trapping rate is improved.)

1. A method for flotation removal and degradation of dioxin in household garbage incineration fly ash is characterized by comprising the following steps: step one, pulping fly ash and water according to a mass ratio of 1: 5-1: 10 to obtain water mortar;

adding hydrochloric acid into the water mortar for size mixing to dissolve calcium ions in the fly ash to obtain high-calcium water mortar;

step three, carrying out flotation on the high-calcium water lime slurry; calcium ions in the high-calcium water mortar increase the electric repulsion force on the surfaces of the air bubbles and inhibit the coalescence among the air bubbles; meanwhile, the existence of calcium ions compresses an electric double layer in the high-calcium water mortar, so that a wetting film between bubbles and particles is thinned and broken, stable bubble-particle aggregates are formed, and the flotation separation of micro-carbon particles is promoted; separating flotation liquid, flotation tail ash and flotation foam from the high-calcium water ash slurry by flotation;

step four, evaporating and crystallizing the flotation solution to recover calcium chloride; rinsing, dehydrating and drying the flotation foam to obtain carbon residue;

adding a photocatalyst into the carbon slag, and then placing the carbon slag in a discharge reaction zone of a low-temperature plasma reactor for discharge reaction; the photocatalyst adopts titanium dioxide with anatase crystalline phase; the low-temperature plasma generated in the discharging process oxidizes and degrades dioxin in the carbon slag; meanwhile, the low-temperature plasma reactor generates ultraviolet light in the discharge process; the ultraviolet light excites the photocatalyst in the carbon residue to carry out photocatalytic oxidation on the dioxin in the carbon residue.

2. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: in the second step, the dosage of the hydrochloric acid relative to the fly ash is 0.5-0.75L/kg, and the mass concentration of the hydrochloric acid is 20-35%.

3. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: and in the third step, adding a collecting agent into the high-calcium cement mortar before flotation, and stirring for reaction for 2-7 min.

4. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: the collecting agent adopts diesel oil or kerosene; the amount of collector used relative to the high calcium aqueous slurry is less than or equal to 0.15 kg/t.

5. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: the specific process for carrying out flotation on the high-calcium water lime slurry is as follows: conveying the high-calcium water mortar into a flotation machine, introducing air into the flotation machine for bubble scraping, wherein the air inflation amount is 0.07-0.12 m³The flotation time is 6-10 min, and primary flotation liquid, primary flotation tail ash and primary flotation foam are obtained; and (3) carrying out secondary electrolytic flotation on the primary flotation tail ash, wherein the flotation time is 3-8 min, and obtaining secondary flotation liquid, secondary flotation tail ash and secondary flotation foam.

6. The method for flotation removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 5, characterized in that: performing primary rinsing on primary flotation foam; secondary rinsing is carried out on the secondary flotation foam; the primary rinsing and the secondary rinsing are repeated for 2-3 times; clear water is used for secondary rinsing; the first-stage rinsing uses rinsing liquid generated by the second-stage rinsing; the rinsing liquid generated by the primary rinsing is used for mixing with fly ash for pulping in the step one.

7. The method for flotation removal and degradation of dioxin in incineration fly ash of household garbage according to claim 5 or 6, characterized in that: the secondary electrolytic flotation adopts an electrolytic flotation cell for flotation; the anode in the electrolytic flotation cell adopts a metal oxide coating electrode, and the cathode adopts a medium-overpotential metal iron electrode.

8. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: and (4) washing the flotation tail ash obtained in the step three for multiple times, and then using the washed flotation tail ash for sintering ceramsite.

9. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: in the fifth step, the addition amount of the photocatalyst relative to the carbon residue is 0.01-0.1%.

10. The method for flotation, removal and degradation of dioxin in fly ash from incineration of household garbage according to claim 1, characterized in that: and fifthly, the discharge reaction time of the low-temperature plasma reactor is 5-15 min, the discharge peak-to-peak voltage is 15-20 kV, and the discharge power is 9-12W.

Technical Field

The invention belongs to the technical field of treatment of household garbage incineration fly ash, and particularly relates to a method for removing and degrading dioxin in household garbage incineration fly ash by flotation.

Background

Although the harmless treatment of the household garbage incineration has the obvious advantages of volume reduction, decrement, resource utilization and the like, secondary pollution mainly comprises conventional pollutants (such as COx, SOx, NOx, HCl and HI), special pollutants (heavy metals, Volatile Organic Compounds (VOCs), Polycyclic Aromatic Hydrocarbons (PAHs) and dioxin dioxins), ultrafine particles and the like in the household garbage incineration process. Dioxin is highly concerned by the public because of high toxicity and slow degradation.

The dioxin control technology widely used in the domestic waste incineration process at present is an activated carbon injection and cloth bag dust removal technology. The content of dioxin suspended in the gas phase before the flue gas enters the bag-type dust collector at 200 ℃ is generally more than 90 percent. The activated carbon has the advantages of large adsorption capacity and good adsorption performance due to the huge specific surface area and the micropore structure, and can simultaneously adsorb gas-phase suspended dioxin and volatile heavy metals, so that the flue gas is discharged after being purified to reach the standard. Meanwhile, the flue gas purification system collects fine particulate matters, namely the waste incineration fly ash, which contains heavy metals with high leaching toxicity and high-content dioxin, and the content of chloride and calcium oxide is up to more than 50%.

Because the physicochemical characteristics of the heavy metals enriched in the fly ash are greatly different from those of dioxin, the dioxin has high hydrophobicity and lipophilicity and extremely strong nonpolar characteristics, and the difficulty of harmless treatment of the fly ash is increased. At present, the treatment methods of the waste incineration fly ash mainly comprise melting/glass solidification, cement solidification, chemical stabilization, acid or other solvent elution and the like. The methods generally have the characteristics of large energy consumption, single toxicity reduction, low efficiency, serious secondary pollution, poor applicability and the like, for example, an extraction and separation method, a chemical stabilization method and a solidification method mainly aim at the treatment of heavy metals, do not relate to the toxic degradation of dioxin, and generate a large amount of wastewater to be treated; although the heat treatment method can stabilize heavy metals in the fly ash and effectively degrade persistent organic pollutants in the fly ash, the technical popularization and application are limited by the problems of high treatment cost, high equipment requirement, secondary pollution and the like.

Therefore, the invention aims to provide a method for flotation removal and degradation of dioxin in household garbage incineration fly ash, which realizes separation and removal of dioxin in household garbage incineration fly ash.

Disclosure of Invention

The invention aims to provide a method for removing and degrading dioxin in household garbage incineration fly ash by flotation;

the method comprises the following specific steps:

step one, pulping fly ash and water according to a mass ratio of 1: 5-1: 10 to obtain water mortar.

And step two, adding hydrochloric acid into the water-based mortar for size mixing to dissolve out calcium ions in the fly ash, thereby obtaining the high-calcium water-based mortar.

And step three, carrying out flotation on the high-calcium water lime slurry. Calcium ions in the high-calcium aqueous slurry increase the electrical repulsive force of the surfaces of the air bubbles, and inhibit coalescence between the air bubbles. Meanwhile, the existence of calcium ions compresses an electric double layer in the high-calcium water mortar, so that the wetting film between bubbles and particles is thinned and broken, stable bubble-particle aggregates are formed, and the flotation separation of micro-carbon particles is promoted. Separating flotation liquid, flotation tail ash and flotation foam from the high-calcium water ash slurry by flotation.

Step four, evaporating and crystallizing the flotation solution to recover calcium chloride; and rinsing, dehydrating and drying the flotation foam to obtain carbon residue.

And fifthly, adding a photocatalyst into the carbon slag, and then placing the carbon slag in a discharge reaction area of a low-temperature plasma reactor for discharge reaction. The photocatalyst adopts titanium dioxide with anatase crystalline phase. The low-temperature plasma generated in the discharging process oxidizes and degrades dioxin in the carbon slag; meanwhile, the low-temperature plasma reactor generates ultraviolet light in the discharge process; the ultraviolet light excites the photocatalyst in the carbon residue to carry out photocatalytic oxidation on the dioxin in the carbon residue.

Preferably, in the second step, the dosage of the hydrochloric acid relative to the fly ash is 0.5-0.75L/kg, and the mass concentration of the hydrochloric acid is 20-35%.

Preferably, in the third step, a collecting agent is added into the high-calcium water mortar before flotation, and the high-calcium water mortar is stirred and reacts for 2-7 min.

Preferably, the collecting agent adopts diesel oil or kerosene; the amount of collector used relative to the high calcium aqueous slurry is less than or equal to 0.15 kg/t.

Preferably, the specific process of flotation of the high-calcium water lime slurry is as follows: conveying the high-calcium water mortar into a flotation machine, introducing air into the flotation machine for bubble scraping, wherein the air inflation amount is 0.07-0.12 m³And h, carrying out flotation for 6-10 min to obtain primary flotation solution, primary flotation tail ash and primary flotation foam. And (3) carrying out secondary electrolytic flotation on the primary flotation tail ash, wherein the flotation time is 3-8 min, and obtaining secondary flotation liquid, secondary flotation tail ash and secondary flotation foam.

Preferably, the primary flotation froth is subjected to a primary rinse; secondary rinsing is carried out on the secondary flotation foam; and the primary rinsing and the secondary rinsing are repeated for 2-3 times. Clear water is used for secondary rinsing; the first rinsing uses the rinsing liquid produced by the second rinsing. The rinsing liquid generated by the primary rinsing is used for mixing with fly ash for pulping in the step one.

Preferably, the second electrolytic flotation is performed by using an electrolytic flotation cell. The anode in the electrolytic flotation cell adopts a metal oxide coating electrode, and the cathode adopts a medium-overpotential metal iron electrode.

Preferably, the flotation tail ash obtained in the third step is washed for multiple times and then is used for sintering ceramsite.

Preferably, in the fifth step, the addition amount of the photocatalyst relative to the carbon residue is 0.01-0.1%;

preferably, in the step five, the discharge reaction time of the low-temperature plasma reactor is 5-15 min, the discharge peak voltage is 15-20 kV, and the discharge power is 9-12W.

The invention has the beneficial effects that:

1、the invention utilizes the characteristics of high content of high chloride salt and calcium oxide of the fly ash, adds hydrochloric acid for size mixing to further enhance the salt concentration of mortar and the dissolution amount of divalent calcium ions, and simultaneously dissolves various divalent (Zn) ions²⁺、Cu²⁺、Fe²⁺、Mg²⁺Etc.) and trivalent (Al)^{3 +}、Fe³⁺) The metal ions in the mortar improve the ionic charge in the mortar, and the effects of inhibiting the coalescence degree of bubbles and improving the stability of foams are achieved; therefore, under the condition of not adding a foaming agent, the bubble effect in the flotation process is ensured, and the fly ash carbon residue trapping rate is improved; therefore, a foaming agent is saved in the flotation process, and the cost of the agent is saved; in addition, the addition of hydrochloric acid enables calcium ions in the fly ash to be dissolved out in a large quantity, so that the fly ash flotation tail ash is beneficial to carrying out ceramsite sintering and recycling (the total calcium content in raw material components is limited to be less than 10 percent by firing in a kiln), and calcium chloride can be recovered through evaporative crystallization.

2. According to the invention, anatase phase titanium dioxide serving as a photocatalyst is added into a low-temperature plasma reactor together, and the anatase phase titanium dioxide is excited by utilizing ultraviolet light naturally generated by the low-temperature plasma reactor, so that a low-temperature plasma coupling photocatalysis technology is realized under the condition of no independent ultraviolet light source; the floated carbon residue (activated carbon) is regenerated/activated under the coupling action of low-temperature plasma and photocatalysis, so that dioxin is completely degraded, and the porous structure and high adsorption activity of the surface of the activated carbon are retained. In addition, the anatase phase titanium dioxide selected by the invention has the characteristic of strong ultraviolet light absorption capacity, and is used as a catalytic activity center in the activated carbon activation process, so that the anatase phase titanium dioxide is an important reason for realizing photocatalytic oxidation without an independent light source.

3. The electrolytic flotation in the invention utilizes the electrolyzed water to obtain the microbubbles, the size of the generated bubbles can be reduced to the nanometer level, and the generated bubbles have strong floating carrying capacity, so that the collision adhesion probability between the fine-grained carbon and the bubbles is increased, and the recovery rate of the fine-grained carbon is improved; meanwhile, the electrolytic flotation can effectively reduce Cu in the mortar²⁺、Zn²⁺、Pb²⁺、Cd²⁺And (4) the content of heavy metal ions is equal.

4. The mortar has the characteristics of high calcium and high salt, so that the mortar has good dispersibility; only a small amount of collecting agent is added to improve the hydrophobicity of the carbon surface, so that the probability of the adhesion of carbon particles and bubbles is increased, the carbon flotation efficiency is improved, and the using amount of the collecting agent and the flotation cost are reduced.

5. In the invention, the carbon particles rich in dioxin are almost completely separated out by high-efficiency flotation, and in addition, the dioxin is a strong hydrophobic organic matter and is captured and carried upwards along with bubbles in the flotation process to be removed.

Detailed Description

The technical solution of the present invention is described in detail below with reference to specific technical details.

A method for removing dioxin by floating, decarbonizing and removing fly ash generated by burning household garbage comprises the following steps:

(1) and pulping fly ash obtained by burning garbage and water according to the mass ratio of 1: 5-1: 10, and stirring for 5-10 min to obtain the water-based mortar.

(2) And adding hydrochloric acid into the water-containing mortar for size mixing, and stirring for reaction for 10-30 min to dissolve calcium ions in the fly ash out to obtain the high-calcium water-containing mortar. The mass concentration of the hydrochloric acid added in the size mixing process is adjusted according to different fly ash components, the size of generated bubbles and the amount of foam, and 32% is preferred in the embodiment. The amount of hydrochloric acid used was 0.5L/kg relative to fly ash. The more hydrochloric acid is added, the Ca in the fly ash²⁺The more ions are dissolved out, the more CaCl with higher concentration is formed₂Salt solution, and other trivalent metal ions (Al) are dissolved out³⁺、Fe³⁺) And divalent metal ion (Zn)²⁺、Cu²⁺、Fe²⁺、Mg²⁺Etc.) increase the ionic species charge and salt concentration in the mortar, the high salt concentrate inhibits the coalescence of bubbles, and this effect increases with the increase in the valence of the salt solution ions, thereby reducing the bubble size and increasing the foam stability, in which process the generated metal ions mainly composed of calcium ions can play a role equivalent to a foaming agent.

(3) Adding the collecting agent into the high-calcium water mortar, and stirring and reacting for 2-7 min to obtain the high-calcium water mortar containing the collecting agent; the collecting agent is diesel oil or kerosene, and only a trace amount of collecting agent needs to be added. In the embodiment, the amount of the collector used relative to the high-calcium water-based mortar is 0-0.15 kg/t. The high calcium and high salt water solution provides fly ash with good dispersibility. The surface hydrophobicity of the micro-carbon particles in the fly ash can be further improved by adding the collecting agent, so that the adhesion probability of the micro-carbon particles and bubbles is enhanced, the carbon flotation efficiency is improved, the consumption of the collecting agent is extremely low when the amount of the collecting agent is calculated by the fly ash per ton.

(4) Conveying the high-calcium water mortar containing the collecting agent into a flotation machine, introducing air into the flotation machine for scraping bubbles, wherein the aeration quantity is 0.07-0.12 m³And h, carrying out flotation for 6-10 min to obtain primary flotation solution, primary flotation tail ash and primary flotation foam. A large amount of calcium chloride is dissolved in the floated high-calcium water mortar; calcium chloride, as an inorganic electrolyte, affects the coalescence of bubbles in an aqueous solution and the transfer of interfacial gas, and increases the concentration of the electrolyte to increase the electrical repulsion on the surfaces of the bubbles and inhibit the coalescence of the bubbles. The two-phase contact of the bubbles and particles creates an electrical potential between the two phases (due to charge separation). Two phases have excessive charges respectively, the electric quantity is equal, the signs are opposite, and the two phases attract each other to form an electric double layer. The compression of the electric double layer in the brine enhances the thinning and rupture of the wetting film between the bubbles and particles, which is a critical step in the formation of stable bubble-particle aggregates, and the flotation kinetics in the presence of salt is faster than conventional flotation, since the presence of salt compresses the electric double layer, promoting the bubble-particle adhesion process. The increase in salt concentration destabilizes the hydration layer around the microcarbon particles, which in turn promotes drainage of water films between bubbles and particles, thereby making the microcarbon particles more amenable to flotation.

(5) Performing secondary electrolytic flotation on the primary flotation tail ash, effectively recovering fine granular carbon, and enhancing flotation decarburization efficiency, wherein no reagent is added in the process, the flotation time is 3-8 min, and secondary flotation liquid, secondary flotation tail ash and secondary flotation foam are obtained; the secondary electrolytic flotation adopts an electrolytic flotation cell for flotation, and micro bubbles with strong loading capacity separated out on an electrode in the electrolytic flotation process are utilized to float hydrophobic carbon particles and hydrophobic impurities. The anode in the electrolytic flotation cell adopts a metal oxide coating electrode, and the cathode adopts a medium-overpotential metal iron electrode;

(6) evaporating and crystallizing the primary flotation solution and the secondary flotation solution, and recovering calcium chloride; pretreating the primary flotation foam and the secondary flotation foam to obtain clean carbon slag; the pretreatment process comprises primary rinsing, secondary rinsing, dehydration and drying; the first-stage rinsing is to rinse the primary flotation foam for 2-3 times to obtain a first-stage rinsing liquid; and secondary rinsing, namely rinsing the secondary flotation foam for 2-3 times to obtain secondary rinsing liquid. Clear water enters a secondary rinsing process; the secondary rinsing liquid flows back to the primary rinsing process; refluxing the primary rinsing liquid to the step (1) for pulping; thereby realizing zero discharge of rinsing wastewater, continuously accumulating the metal ion concentration in the front-end pulping and size mixing process and promoting flotation and decarburization; and after the rinsing is finished, dehydrating and drying the solid phase obtained by the primary rinsing and the secondary rinsing to obtain the clean carbon residue.

(7) Conveying the clean carbon slag to a dioxin degradation unit for harmless regeneration treatment, and specifically comprising the following steps: adding a photocatalyst into the powdery clean carbon residue after pretreatment. The photocatalyst adopts titanium dioxide with powder anatase crystalline phase, and the addition amount is 0.01-0.1%; and then placing the clean carbon slag mixed with the photocatalyst in a discharge reaction zone of a low-temperature plasma reactor for discharge reaction, wherein the discharge reaction time is 5-15 min, the discharge peak voltage is 15-20 kV, and the discharge power is 9-12W.

Oxidizing and degrading dioxin in the clean carbon slag by low-temperature plasma generated in the discharging process; meanwhile, the low-temperature plasma reactor can generate ultraviolet light in the discharge process; the ultraviolet light excites the titanium dioxide of anatase crystalline phase in the clean carbon slag to carry out photocatalytic oxidation on the dioxin. Because the titanium dioxide with anatase crystalline phase has good absorption capacity to ultraviolet light; therefore, the invention can realize the catalytic oxidation of dioxin only by the ultraviolet light generated in the process of generating low-temperature plasma without arranging an independent ultraviolet light source. Because the dioxin is subjected to the synergistic action of the low-temperature plasma and the photocatalyst, the method can more fully and quickly realize the oxidative degradation of the dioxin and the regeneration and activation of the activated carbon.

(8) And (4) washing the primary flotation tail ash and the secondary flotation tail ash for multiple times, and then sintering the ceramsite to realize resource utilization.

The technical effects of the invention are described in the following by combining the specific case of the fly ash from waste incineration:

example 1

The adopted waste incineration fly ash is fly ash produced by Hangzhou Jiufeng domestic waste incineration power plants. The fly ash comprises the following components (in mass fraction): chlorine content of 17%, SiO₂4.5% of CaO, 37.3% of Na₂O content 6.2%, K₂The O content was 4.4%.

The specific operation steps are as follows: (1) pulping 100g of fly ash and water according to the grey water ratio of 1:10, and stirring for 5min to obtain water-cement mortar; (2) adding 50mL of 32% hydrochloric acid for size mixing, and stirring for reaction for 15min to obtain high-calcium water-lime slurry; (3) adding 0.02kg/t of kerosene collecting agent into high-calcium water mortar, and stirring and reacting for 6min to obtain high-calcium water mortar containing the collecting agent; (4) conveying the high-calcium water lime slurry containing the collecting agent into a flotation machine by a pump, and introducing 0.07m into the flotation machine³Blowing bubbles for 7min after air is blown for h to obtain primary flotation tail ash and primary flotation foam; (5) feeding the primary flotation tail ash into an electrolytic flotation cell for flotation and foam scraping for 5min to obtain secondary flotation tail ash and secondary flotation foam; (6) evaporating and crystallizing the primary flotation solution and the secondary flotation solution, and recovering calcium chloride; pretreating primary flotation foam and secondary flotation foam, enabling the primary flotation foam to enter a primary rinsing stage, enabling the secondary flotation foam to enter a secondary rinsing stage, enabling clear water to enter the secondary rinsing stage for rinsing, enabling a secondary rinsing solution to flow back to the primary rinsing stage for rinsing, enabling the primary rinsing solution to flow back to the step (1) for pulping, achieving zero emission of rinsing wastewater, completing the whole rinsing process for 2-3 times, and dehydrating and drying solid phases obtained in the primary rinsing stage and the secondary rinsing stage to obtain clean carbon residues; (7) performing harmless regeneration treatment on the pretreated clean carbon slag by adopting a low-temperature plasma coupling photocatalysis technology, adding 0.01 percent of powdered anatase phase titanium dioxide photocatalyst into the powdered clean carbon slag, and then placing the powdered clean carbon slag into a discharge area of a low-temperature plasma reactor for discharge reaction10min, the discharge peak voltage is 15kV, and the discharge power is 9W.

Comparative example 1

Comparative example 1 differs from example 1 in that: a conventional secondary octanol foaming agent was used in place of the hydrochloric acid in step (2) in an amount of 0.2 kg/t.

Table 1 index comparison of example 1 and comparative example 1

As can be seen from Table 1, under the condition that the collecting agent conditions are the same, the hydrochloric acid is added for size mixing to prepare the high-calcium high-salt aqueous solution, when metal ions are dissolved for subsequent evaporation and crystallization, a good foaming effect can be achieved without adding a foaming agent, the fly ash carbon residue trapping rate is 90.37%, and the high-calcium high-salt aqueous solution is superior to that of the conventional secondary octanol foaming agent (the fly ash carbon residue trapping rate is 86.78%) added in comparative example 1; in addition, the degradation rate of the dioxin in the carbon slag reaches 99.37 percent and the regeneration rate of the carbon slag reaches 95.33 percent by means of the degradation of the dioxin by low-temperature plasma and the photocatalytic oxidation effect generated after the activation of the photocatalyst.

Example 2

The waste incineration fly ash adopted is fly ash produced by a Hangzhou Dajiang east domestic waste incineration power plant. The fly ash comprises the following components (in mass fraction): chlorine content 5.0%, SiO₂20.0% of CaO, 36.9% of Na₂O content of 2.0%, K₂The O content was 1.5%.

The specific operation steps are as follows: (1) 100g of fly ash and water are mixed according to the grey water ratio of 1: pulping for 10min, and stirring for 5min to obtain water mortar; (2) adding 70mL of 32% hydrochloric acid for size mixing, and stirring for reaction for 15min to obtain high-calcium water-lime slurry; (3) adding 0.02kg/t of kerosene collecting agent into high-calcium water mortar, and stirring and reacting for 6min to obtain high-calcium water mortar containing the collecting agent; (4) conveying the high-calcium water lime slurry containing the collecting agent into a flotation machine by a pump, and introducing 0.07m into the flotation machine³Blowing bubbles for 7min after air is blown for h to obtain primary flotation tail ash and primary flotation foam; (5) feeding the primary flotation tail ash into an electrolytic flotation cellCarrying out flotation and foam scraping for 5min to obtain secondary flotation tail ash and secondary flotation foam; (6) evaporating and crystallizing the primary flotation solution and the secondary flotation solution, and recovering calcium chloride and other metal salts; pretreating primary flotation foam and secondary flotation foam, enabling the primary flotation foam to enter a primary rinsing stage, enabling the secondary flotation foam to enter a secondary rinsing stage, enabling clear water to enter the secondary rinsing stage for rinsing, enabling a secondary rinsing solution to flow back to the primary rinsing stage for rinsing, enabling the primary rinsing solution to flow back to the step (1) for pulping, achieving zero emission of rinsing wastewater, completing the whole rinsing process for 2-3 times, and dehydrating and drying solid phases obtained in the primary rinsing stage and the secondary rinsing stage to obtain clean carbon residues; (7) and performing harmless regeneration treatment on the pretreated clean carbon slag by adopting a low-temperature plasma coupling photocatalysis technology, adding 0.01% of powdered anatase phase titanium dioxide photocatalyst into the powdered clean carbon slag, and then placing the powdered clean carbon slag into a discharge area of a low-temperature plasma reactor for discharge reaction for 10min, wherein the discharge peak voltage is 20kV, and the discharge power is 12W.

Comparative example 2

Comparative example 2 differs from example 2 in that: a conventional secondary octanol foaming agent was used in place of the hydrochloric acid in step (2) in an amount of 0.2 kg/t.

The results of flotation using the above example 2 and comparative example 2 are shown in table 2.

Table 2 index comparison of example 2 and comparative example 2

As can be seen from Table 2, under the condition that the collecting agent conditions are the same, the hydrochloric acid is added for size mixing to prepare the high-calcium high-salt aqueous solution, when metal ions are dissolved for subsequent evaporation and crystallization, a good foaming effect can be achieved without adding a foaming agent, the fly ash carbon residue trapping rate is 91.09%, and the fly ash carbon residue trapping rate is superior to that of the conventional sec-octanol foaming agent added in comparative example 1 (the fly ash carbon residue trapping rate is 86.10%); in addition, the degradation rate of the dioxin in the carbon slag reaches 99.86 percent and the regeneration rate of the carbon slag reaches 96.75 percent by means of the degradation of the dioxin by low-temperature plasma and the photocatalytic oxidation effect generated after the activation of the photocatalyst.

Example 3

The waste incineration fly ash adopted is the fly ash produced by Hangzhou Xiaoshan urban domestic waste incineration power plants. The properties of the fly ash are as follows: chlorine content 7.3%, SiO₂13.8% of CaO, 37.2% of CaO, and Na₂O content 2.7%, K₂The O content was 1.9%. The specific operation steps are as follows: (1) 100g of fly ash and water are mixed according to the grey water ratio of 1: pulping for 10min, and stirring for 5min to obtain water mortar; (2) adding 75mL of 32% hydrochloric acid for size mixing, and stirring for reaction for 15min to obtain high-calcium water-lime slurry; (3) adding 0.02kg/t of kerosene collecting agent into high-calcium water mortar, and stirring and reacting for 6min to obtain high-calcium water mortar containing the collecting agent; (4) conveying the high-calcium water lime slurry containing the collecting agent into a flotation machine by a pump, and introducing 0.07m into the flotation machine³Blowing bubbles for 7min after air is blown for h to obtain primary flotation tail ash and primary flotation foam; (5) feeding the primary flotation tail ash into an electrolytic flotation cell for flotation and foam scraping for 5min to obtain secondary flotation tail ash and secondary flotation foam; (6) evaporating and crystallizing the primary flotation solution and the secondary flotation solution, and recovering calcium chloride and other metal salts; pretreating primary flotation foam and secondary flotation foam, enabling the primary flotation foam to enter a primary rinsing stage, enabling the secondary flotation foam to enter a secondary rinsing stage, enabling clear water to enter the secondary rinsing stage for rinsing, enabling a secondary rinsing solution to flow back to the primary rinsing stage for rinsing, enabling the primary rinsing solution to flow back to the step (1) for pulping, achieving zero emission of rinsing wastewater, completing the whole rinsing process for 2-3 times, and enabling solid phases obtained in the primary rinsing stage and the secondary rinsing stage to be dehydrated and dried to obtain clean carbon residues; (7) and performing harmless regeneration treatment on the pretreated clean carbon slag by adopting a low-temperature plasma coupling photocatalysis technology, adding 0.05 percent of powdery anatase phase titanium dioxide photocatalyst into the powdery clean carbon slag, and then placing the powdery clean carbon slag into a discharge area of a low-temperature plasma reactor for discharge reaction for 10min, wherein the discharge peak voltage is 15kV, and the discharge power is 9W.

Comparative example 3

Comparative example 3 differs from example 3 in that: a conventional secondary octanol foaming agent was used in place of the hydrochloric acid in step (2) in an amount of 0.2 kg/t.

The results of flotation using the above example 3 and comparative example 3 are shown in table 3.

Table 3 index comparison of example 3 and comparative example 3

As can be seen from Table 3, under the same collecting agent conditions, the high-calcium high-salt aqueous solution prepared by adding hydrochloric acid for size mixing can achieve good foaming effect under the condition of dissolving metal ions for subsequent evaporation and crystallization and without adding a foaming agent, and the capture rate of fly ash carbon residue is 92.75 percent, which is superior to that of the conventional secondary octanol foaming agent added in comparative example 1 (the capture rate of fly ash carbon residue is 85.16 percent); in addition, the degradation rate of the dioxin in the carbon slag reaches 99.83 percent and the regeneration rate of the carbon slag reaches 96.54 percent by means of the degradation of the dioxin by low-temperature plasma and the photocatalytic oxidation effect generated after the activation of the photocatalyst.

Example 4

The adopted waste incineration fly ash is fly ash produced by a Binjiang domestic waste incineration power plant in Hangzhou city. The properties of the fly ash are as follows: chlorine content 15.4%, SiO₂6.5% of CaO, 22.5% of Na₂O content 11.5%, K₂The O content was 4.2%.

The specific operation steps are as follows: (1) 100g of fly ash and water are mixed according to the grey water ratio of 1: pulping for 10min, and stirring for 5min to obtain water mortar; (2) adding 55mL of 32% hydrochloric acid for size mixing, and stirring for reaction for 15min to obtain high-calcium water-lime slurry; (3) adding 0.02kg/t of kerosene collecting agent into high-calcium water mortar, and stirring and reacting for 6min to obtain high-calcium water mortar containing the collecting agent; (4) conveying the high-calcium water lime slurry containing the collecting agent into a flotation machine by a pump, and introducing 0.07m into the flotation machine³Blowing bubbles for 7min after air is blown for h to obtain primary flotation tail ash and primary flotation foam; (5) feeding the primary flotation tail ash into an electrolytic flotation cell for flotation and foam scraping for 5min to obtain secondary flotation tail ash and secondary flotation foam; (6)evaporating and crystallizing the primary flotation solution and the secondary flotation solution, and recovering calcium chloride and other metal salts; pretreating primary flotation foam and secondary flotation foam, enabling the primary flotation foam to enter a primary rinsing stage, enabling the secondary flotation foam to enter a secondary rinsing stage, enabling clear water to enter the secondary rinsing stage for rinsing, enabling a secondary rinsing solution to flow back to the primary rinsing stage for rinsing, enabling the primary rinsing solution to flow back to the step (1) for pulping, achieving zero emission of rinsing wastewater, completing the whole rinsing process for 2-3 times, and enabling solid phases obtained in the primary rinsing stage and the secondary rinsing stage to be dehydrated and dried to obtain clean carbon residues; (7) and performing harmless regeneration treatment on the pretreated clean carbon slag by adopting a low-temperature plasma coupling photocatalysis technology, adding 0.05 percent of powdery anatase phase titanium dioxide photocatalyst into the powdery clean carbon slag, and then placing the powdery clean carbon slag into a discharge area of a low-temperature plasma reactor for discharge reaction for 10min, wherein the discharge peak voltage is 20kV, and the discharge power is 12W.

Comparative example 4

Comparative example 4 differs from example 4 in that: a conventional secondary octanol foaming agent was used in place of the hydrochloric acid in step (2) in an amount of 0.2 kg/t.

The results of flotation using the above example 4 and comparative example 4 are shown in table 4.

Table 4 index comparison of example 4 and comparative example 4

As can be seen from Table 4, under the condition that the collecting agent conditions are the same, the hydrochloric acid is added for size mixing to prepare the high-calcium high-salt aqueous solution, when metal ions are dissolved for subsequent evaporation and crystallization, a good foaming effect can be achieved without adding a foaming agent, the fly ash carbon residue trapping rate is 90.05%, and the fly ash carbon residue trapping rate is superior to that of the comparative example 1 in which a conventional sec-octanol foaming agent is added (the fly ash carbon residue trapping rate is 83.85%); in addition, the degradation rate of the dioxin in the carbon slag reaches 99.95 percent and the regeneration rate of the carbon slag reaches 97.12 percent by means of the degradation of the dioxin by low-temperature plasma and the photocatalytic oxidation effect generated after the activation of the photocatalyst.

It can be seen that the fly ash carbon residue collection rate of 90% or more can be achieved by collecting the dioxin-rich carbon particles in the fly ash by flotation according to the schemes of the above examples 1 to 4. After pretreatment, the flotation foam product is subjected to low-temperature plasma coupling photocatalysis harmless treatment, the degradation rate of dioxin in the flotation carbon residue reaches 99%, and the regeneration rate of carbon residue reaches more than 95%.