Waste incineration fly ash harmless recycling method based on low temperature

Abstract

The invention relates to a waste incineration fly ash harmless recycling method based on low temperature, and belongs to the technical field of fly ash harmless treatment.The fly ash harmless recycling method comprises the steps that fly ash, auxiliary materials and a catalyst are evenly mixed, and a mixture is obtained; the auxiliary material comprises phosphate; the catalyst is obtained by reacting a mixed system containing titanyl sulfate, ammonium metavanadate, sodium acetate and sodium isethionate; the mass ratio of titanyl sulfate to ammonium metavanadate to sodium acetate to sodium isethionate is 100: (0.5-3): (5-10): (3-6); and the mixture is subjected to mechanical alloying treatment, extrusion forming granulation and heat treatment, and a harmless recycling product is obtained. By means of the harmless recycling method for the fly ash, fixation of heavy metal and decomposition of dioxin at the low temperature can be achieved, the harmless recycling treatment process is high in efficiency and low in energy consumption, and the obtained harmless recycling product is lasting in heavy metal stabilizing effect, low in dioxin content and low in heavy metal leaching concentration.

Description

Technical Field

[0001] The invention relates to the technical field of harmless treatment of fly ash, and in particular to a harmless resource utilization method of waste incineration fly ash based on low temperature. Background Art

[0002] The incineration process of domestic waste will produce fly ash of 3% to 5% of the amount of waste (based on the mainstream grate furnace incinerator). In 2022, the national waste incineration fly ash production has exceeded 10 million tons. Waste incineration fly ash is a special solid waste with high salt content and rich pollutants such as heavy metals and dioxins. It is listed in the national hazardous waste list, so it is necessary to attach great importance to the safe disposal of waste incineration fly ash.

[0003] Waste incineration fly ash contains a wealth of recyclable components. The cement kiln co-treatment of incineration fly ash technology can realize fly ash resource utilization to a certain extent, while saving land resources occupied by landfill, but the added value it achieves is low, the process is complex, the cost of fly ash disposal is much higher than the cost of landfill technology, and my country is currently facing problems such as overcapacity in the cement industry and the distribution of cement production industries, which limits the sustainable development and widespread application of this technology.

[0004] Heat treatment of fly ash can decompose organic matter such as dioxins and stabilize heavy metals, which is one of the hot research directions at present. The high-temperature melting treatment technology of fly ash can achieve the complete harmlessness, reduction and resource utilization of fly ash resources, and can obtain higher value-added products. However, high-temperature melting requires heating the fly ash to 1300℃~1600℃, and the disposal process consumes a lot of energy. The cost of fly ash disposal is much higher than the cost of ton fly ash disposal in the cement kiln collaborative process route. Most of the high-temperature sintering of fly ash needs to be carried out at a high temperature of 1100℃, and the process energy consumption is also very high. Therefore, reducing the heat treatment temperature of fly ash, reducing the energy consumption of the process, and improving the economic benefits of the fly ash disposal process have become scientific and technological problems that urgently need to be solved in the field of fly ash resource utilization. Developing the process technology of low-temperature heat treatment of fly ash and realizing the detoxification and resource utilization of fly ash will surely become an important development direction of waste incineration fly ash disposal technology in the future. Summary of the invention

[0005] In view of one or more technical problems existing in the prior art, the present invention provides a harmless resource utilization method for waste incineration fly ash based on low temperature. The harmless resource utilization method for fly ash provided by the present invention can achieve the fixation of heavy metals and the decomposition of dioxins at low temperature. The harmless resource disposal process has high efficiency and low energy consumption. The obtained harmless resource product has a long-lasting heavy metal stabilization effect, a low dioxin content, and a low heavy metal leaching concentration.

[0006] In a first aspect, the present invention provides a method for harmless resource utilization of waste incineration fly ash based on low temperature, the method comprising the following steps:

[0007] The fly ash, auxiliary materials and catalyst are mixed to obtain a mixture; the auxiliary materials include phosphate; the catalyst is obtained by reacting a mixed system including titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate; the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate is 100:0.5-3:5-10:3-6;

[0008] The mixed material is subjected to mechanical alloying treatment, extrusion molding granulation and heat treatment to obtain a harmless resource product.

[0009] Preferably, the amount of phosphate is 1-3% of the mass of fly ash; and / or

[0010] The phosphate is one or more of sodium phosphate, potassium dihydrogen phosphate, potassium phosphate, and sodium pyrophosphate.

[0011] Preferably, the auxiliary materials further include silicon-based auxiliary materials and metal-based auxiliary materials;

[0012] The metal-based auxiliary material is one or more of magnesium hydroxide, aluminum hydroxide, bauxite powder, aluminum slag powder, magnesium oxide, and magnesium carbonate;

[0013] The silicon-based auxiliary material is one or more of fly ash, steel slag powder, tailings powder, silica ash and fumed silicon dioxide.

[0014] Preferably, the amount of the silicon-based auxiliary material is 10-50% of the mass of the fly ash; and / or

[0015] The amount of the metal-based auxiliary material is 5-25% of the mass of the fly ash.

[0016] Preferably, the amount of the catalyst is 0.01-0.1% of the mass of the fly ash; and / or

[0017] The particle size of the catalyst is no greater than 100 nm.

[0018] Preferably, the reaction temperature is 120-150° C. and the reaction time is 8-12 hours.

[0019] Preferably, the mechanical alloying treatment adopts at least one of ball milling and extrusion.

[0020] Preferably, the ball-to-material ratio of the ball mill is 1:2-3, the ball mill speed is 1000-3000 rpm, and the ball mill time is 15-30 min.

[0021] Preferably, the extrusion pressure is 80-300 MPa and the extrusion time is 15-30 min.

[0022] Preferably, the pressure of the extrusion granulation is not less than 20 MPa; and / or

[0023] The heat treatment is carried out under an inert atmosphere at a temperature of 225 to 325° C. for a time of 30 to 120 min. Preferably, the inert gas content in the inert atmosphere is not less than 98 vol%.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The present invention firstly improves the activity of the interface reaction between solid materials by mechanically alloying the fly ash, auxiliary materials and catalyst mixture, which is beneficial to the stability of heavy metals in the fly ash; then extrude and granulate the material after the mechanical alloying treatment to obtain particles with a certain size; finally, the particles are heat-treated, and the temperature of the heat treatment is reduced by a self-made catalyst, so that the fixation of heavy metals and the decomposition of dioxins at low temperature can be achieved, the cost of the treatment process is greatly reduced, and at the same time, harmless resource products with higher added value can be obtained.

[0026] The fly ash harmless resource utilization method provided by the present invention can achieve the fixation of heavy metals and the decomposition of dioxins at low temperature. The harmless resource utilization disposal process has high efficiency and low energy consumption. The obtained harmless resource utilization product has a long-lasting heavy metal stabilization effect, low dioxin content, and low heavy metal leaching concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a structural schematic diagram of the extrusion device provided by the present invention;

[0029] Figure numerals: 11 - lower hopper; 12 - double roller squeeze rollers; 13 - crusher; 14 - porous screen plate; 15 - material transport component. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] In a first aspect, the present invention provides a method for harmless resource utilization of waste incineration fly ash based on low temperature, the method comprising the following steps:

[0032] The fly ash, auxiliary materials and catalyst are mixed to obtain a mixture; the auxiliary materials include phosphate; the catalyst is obtained by reacting a mixed system including titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate; the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate is 100:0.5-3:5-10:3-6;

[0033] The mixed material is subjected to mechanical alloying treatment, extrusion molding granulation and heat treatment to obtain a harmless resource product.

[0034] The present invention firstly improves the activity of the interface reaction between solid materials by mechanically alloying the fly ash, auxiliary materials and catalyst mixture, which is beneficial to the stability of heavy metals in the fly ash; then extrude and granulate the material after the mechanical alloying treatment to obtain particles with a certain size; finally, the particles are heat-treated, and the temperature of the heat treatment is reduced by a self-made catalyst, so that the fixation of heavy metals and the decomposition of dioxins at low temperature can be achieved, the cost of the treatment process is greatly reduced, and at the same time, harmless resource products with higher added value can be obtained.

[0035] The fly ash harmless resource utilization method provided by the present invention can achieve the fixation of heavy metals and the decomposition of dioxins at low temperature. The harmless resource utilization disposal process has high efficiency and low energy consumption. The obtained harmless resource utilization product has a long-lasting heavy metal stabilization effect, low dioxin content, and low heavy metal leaching concentration.

[0036] According to some preferred embodiments, the amount of phosphate is 1-3% (for example, 1%, 1.2%, 1.5%, 1.6%, 2%, 2.2%, 2.5%, 2.8% or 3%) of the fly ash mass.

[0037] According to some preferred embodiments, the phosphate is one or more of sodium phosphate, potassium dihydrogen phosphate, potassium phosphate, and sodium pyrophosphate. The phosphate of the present invention is a heavy metal stabilizer, which is used to stabilize heavy metals in fly ash.

[0038] According to some preferred embodiments, the auxiliary materials further include silicon-based auxiliary materials and metal-based auxiliary materials;

[0039] The metal-based auxiliary material is one or more of magnesium hydroxide, aluminum hydroxide, bauxite powder, aluminum slag powder, magnesium oxide, and magnesium carbonate;

[0040] The silicon-based auxiliary material is one or more of fly ash, steel slag powder, tailings powder, silica ash and fumed silicon dioxide.

[0041] The present invention can improve the mechanical strength of the prepared harmless resource recovery product by adding silicon-based auxiliary materials and metal-based auxiliary materials to the auxiliary materials, thereby broadening its application scenarios.

[0042] According to some preferred embodiments, the amount of the silicon-based auxiliary material is 10-50% of the mass of the fly ash.

[0043] According to some preferred embodiments, the amount of the metal-based auxiliary material is 5-25% of the mass of the fly ash.

[0044] According to some preferred embodiments, the amount of the catalyst is 0.01-0.1% (for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09% or 0.1%) of the fly ash mass.

[0045] According to some preferred embodiments, the particle size of the catalyst is no greater than 100 nm.

[0046] According to some preferred embodiments, the reaction temperature is 120-150°C (for example, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C), and the reaction time is 8-12h (for example, 8h, 9h, 10h, 11h or 12h).

[0047] According to some preferred embodiments, the preparation method of the catalyst comprises: mixing titanyl sulfate, ammonium metavanadate, sodium acetate, sodium hydroxyethyl sulfonate and water, reacting at 120-150° C. for 8-12 hours, and obtaining the catalyst by solid-liquid separation and drying.

[0048] The present invention reacts titanyl sulfate and ammonium metavanadate under the action of an auxiliary agent (sodium acetate, sodium isethionate) to obtain a vanadium-doped modified titanium dioxide catalyst with small and uniform particle size and excellent catalytic performance. The addition of the auxiliary agent (sodium acetate, sodium isethionate) is beneficial to the regulation of the catalyst morphology and improves its catalytic activity. The vanadium doping amount in the catalyst is regulated by regulating the dosage of titanyl sulfate and ammonium metavanadate.

[0049] According to some preferred embodiments, the amount of water used is 20 to 40 times (for example, 20 times, 25 times, 30 times, 35 times or 40 times) the mass of titanyl sulfate.

[0050] According to some preferred embodiments, the mechanical alloying treatment adopts at least one of ball milling and extrusion.

[0051] According to some preferred embodiments, the ball-to-material ratio of the ball milling is 1:2-3, the ball milling speed is 1000-3000 rpm, and the ball milling time is 15-30 min.

[0052] According to some preferred embodiments, the extrusion pressure is 80 to 300 MPa (for example, 80 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa or 300 MPa), and the extrusion time is 15 to 30 min.

[0053] According to some preferred embodiments, mechanical alloying by extrusion is achieved through an extrusion device, which includes: a lower hopper 11, a pair of rollers 12, a crusher 13, a porous screen plate 14, and a material conveying component 15 connected to the porous screen plate 14 and the lower hopper, which are arranged in sequence from top to bottom; the pair of rollers 12 are used to extrude the material; the crusher 13 is used to crush the extruded material; the porous screen plate 14 is used to screen the extruded material; the material conveying component 15 is used to return the screened material to the lower hopper, and repeat the steps of extrusion-crushing-screening. The material conveying component 15 is preferably one of a bucket elevator and a tube chain conveyor; wherein the pressure of the pair of rollers 12 is 80-300MPa, and the size of the crushed particles is less than 5mm. The device uses the pressure of the pair of rollers to achieve mechanical alloying of the material.

[0054] According to some preferred embodiments, the pressure of the extrusion granulation is not less than 20 MPa; preferably, the size of the particles after the extrusion granulation is 2 to 8 mm. The present invention does not specifically limit the shape of the particles after extrusion granulation, for example, it can be spherical, ellipsoidal, or cylindrical.

[0055] According to some preferred embodiments, the heat treatment is carried out in an inert atmosphere, the heat treatment temperature is 225-325°C (for example, 225°C, 250°C, 275°C, 300°C or 325°C), and the time is 30-120 min; preferably, the inert gas content in the inert atmosphere is not less than 98 vol%. The present invention ensures efficient decomposition of dioxins by performing heat treatment in an inert atmosphere. If the inert gas content is too low, the decomposition efficiency of dioxins is affected.

[0056] In order to more clearly illustrate the technical solutions and advantages of the present invention, the present invention is further described below in conjunction with the examples. The present invention does not specifically limit the sources of the reagents used in the examples and comparative examples, and the reagents can be directly purchased or synthesized by themselves.

[0057] Example 1

[0058] Preparation of catalyst: titanyl sulfate, ammonium metavanadate, sodium acetate, sodium hydroxyethyl sulfonate and water are mixed and reacted at 130° C. for 10 hours. After solid-liquid separation and drying, a catalyst is obtained; wherein the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate is 100:2:6:5, and the amount of water used is 30 times the mass of titanyl sulfate;

[0059] The fly ash, auxiliary material (sodium phosphate, the amount of which is 2% of the fly ash mass) and catalyst (the amount of which is 0.06% of the fly ash mass) are mixed to obtain a mixture;

[0060] The mixed material is subjected to mechanical alloying treatment (using Figure 1 The product is extruded by an extrusion device at a pressure of 150 MPa for 20 min), extrusion granulation, and heat treatment (at a temperature of 300° C. for 60 min) to obtain a harmless resource product.

[0061] Example 2

[0062] Preparation of catalyst: titanyl sulfate, ammonium metavanadate, sodium acetate, sodium hydroxyethyl sulfonate and water are mixed and reacted at 120°C for 12 hours. After solid-liquid separation and drying, the catalyst is obtained; wherein the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate is 100:0.5:5:3, and the amount of water used is 20 times the mass of titanyl sulfate.

[0063] The fly ash, auxiliary material (potassium dihydrogen phosphate, the amount of which is 1% of the fly ash mass) and catalyst (the amount of which is 0.01% of the fly ash mass) are mixed to obtain a mixture;

[0064] The mixed material is subjected to mechanical alloying treatment (using Figure 1 The product was extruded by an extrusion device at a pressure of 300 MPa for 15 min), extrusion granulation, and heat treatment (temperature of 325° C. for 120 min) to obtain a harmless resource product.

[0065] Example 3

[0066] Preparation of catalyst: titanyl sulfate, ammonium metavanadate, sodium acetate, sodium hydroxyethyl sulfonate and water are mixed and reacted at 150°C for 8 hours. After solid-liquid separation and drying, the catalyst is obtained; wherein the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate is 100:3:10:6, and the amount of water used is 20 times the mass of titanyl sulfate.

[0067] The fly ash, auxiliary material (sodium pyrophosphate, the amount of which is 3% of the fly ash mass) and catalyst (the amount of which is 0.1% of the fly ash mass) are mixed to obtain a mixture;

[0068] The mixed material is subjected to mechanical alloying treatment (using Figure 1 The product was extruded by an extrusion device at a pressure of 80 MPa for 30 min), extrusion granulation, and heat treatment (temperature of 225°C for 30 min) to obtain a harmless resource product.

[0069] Example 4

[0070] The method is basically the same as Example 1, except that the mechanical alloying treatment is performed by ball milling, the ball milling speed is 2800 rpm, and the ball milling time is 20 min.

[0071] Example 5

[0072] It is basically the same as Example 1, with the only difference being that the auxiliary materials include silicon-based auxiliary materials (fly ash, with an amount of 40% of the fly ash mass), metal-based auxiliary materials (magnesium oxide, with an amount of 12% of the fly ash mass) and phosphate (sodium phosphate, with an amount of 2% of the fly ash mass).

[0073] Example 6

[0074] It is basically the same as Example 1, with the only difference being that it includes silicon-based auxiliary materials (fly ash, with an amount of 40% of the fly ash mass), metal-based auxiliary materials (magnesium oxide, with an amount of 12% of the fly ash mass) and phosphate (potassium dihydrogen phosphate, with an amount of 1% of the fly ash mass).

[0075] Example 7

[0076] The method is basically the same as Example 1, except that it includes silicon-based auxiliary materials (fly ash, the amount of which is 40% of the mass of the fly ash), metal-based auxiliary materials (magnesium oxide, the amount of which is 12% of the mass of the fly ash) and phosphate (sodium pyrophosphate, the amount of which is 3% of the mass of the fly ash).

[0077] Example 8

[0078] It is basically the same as Example 1, with the only difference being that the auxiliary materials include silicon-based auxiliary materials (tailings powder, used in an amount of 20% of the mass of fly ash), metal-based auxiliary materials (magnesium oxide, used in an amount of 15% of the mass of fly ash) and phosphate (sodium phosphate, used in an amount of 2% of the mass of fly ash).

[0079] In this embodiment 5-8, by introducing silicon-based auxiliary materials and metal-based auxiliary materials into the auxiliary materials, the compressive strength of the harmless resource utilization products obtained can be improved on the basis of ensuring that the stability of heavy metals and the decomposition of dioxins are not affected (tested with reference to GB / T 17431.2-1998 standard). Among them, the compressive strength of the harmless resource utilization product obtained in embodiment 5 is 2.8MPa, the compressive strength of the harmless resource utilization product obtained in embodiment 6 is 2.7MPa, the compressive strength of the harmless resource utilization product obtained in embodiment 7 is 2.4MPa, and the compressive strength of the harmless resource utilization product obtained in embodiment 8 is 1.9MPa. In summary, the present invention can obtain harmless resource utilization products with different compressive strengths by regulating the type and amount of silicon-based auxiliary materials and metal-based auxiliary materials added, which can meet different needs.

[0080] Comparative Example 1

[0081] The process is basically the same as Example 1, except that no catalyst is added.

[0082] Comparative Example 2

[0083] The method is basically the same as Example 1, except that sodium acetate and sodium isethionate are not added during the catalyst preparation process.

[0084] Comparative Example 3

[0085] The method is basically the same as Example 1, except that the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate during the catalyst preparation process is 100:0.4:6:5.

[0086] Comparative Example 4

[0087] The method is basically the same as Example 1, except that the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate during the catalyst preparation process is 100:3.5:6:5.

[0088] Comparative Example 5

[0089] It is basically the same as Example 1, except that titanium dioxide is used as a catalyst.

[0090] Comparative Example 6

[0091] The method is substantially the same as Example 1, except that no auxiliary material (sodium phosphate) is added.

[0092] Comparative Example 7

[0093] The method is basically the same as Example 1, except that the amount of the auxiliary material (sodium phosphate) is 0.5%.

[0094] The performance data of the harmless resource recovery products of the embodiments of the present invention and the comparative examples are shown in Table 1. The test methods of each performance are as follows:

[0095] Dioxin content test: refer to HJ 77.3-2008 standard for testing;

[0096] Heavy metal leaching concentration: tested in accordance with HJ / T 300-2007 standard.

[0097] Table 1. Performance data of harmless resource recovery products of the embodiments of the present invention and the comparative examples

[0098]

[0099]

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-temperature method for harmless resource utilization of waste incineration fly ash, characterized in that: The method comprises the following steps: The fly ash, auxiliary materials and catalyst are mixed to obtain a mixture; the auxiliary materials include phosphate; the catalyst is obtained by reacting a mixed system including titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate; the mass ratio of titanyl sulfate, ammonium metavanadate, sodium acetate and sodium hydroxyethyl sulfonate is 100:0.5-3:5-10:3-6; The mixed material is subjected to mechanical alloying treatment, extrusion molding granulation and heat treatment to obtain a harmless resource product.

2. The method according to claim 1, characterized in that The amount of phosphate is 1-3% of the fly ash mass; and / or The phosphate is one or more of sodium phosphate, potassium dihydrogen phosphate, potassium phosphate, and sodium pyrophosphate.

3. The method according to claim 1, characterized in that: The auxiliary materials also include silicon-based auxiliary materials and metal-based auxiliary materials; The metal-based auxiliary material is one or more of magnesium hydroxide, aluminum hydroxide, bauxite powder, aluminum slag powder, magnesium oxide, and magnesium carbonate; The silicon-based auxiliary material is one or more of fly ash, steel slag powder, tailings powder, silica ash and fumed silicon dioxide.

4. The method according to claim 3, characterized in that The amount of the silicon-based auxiliary material is 10-50% of the mass of the fly ash; and / or The amount of the metal-based auxiliary material is 5-25% of the mass of the fly ash.

5. The method according to claim 1, characterized in that The amount of the catalyst is 0.01-0.1% of the fly ash mass; and / or The particle size of the catalyst is no greater than 100 nm.

6. The method according to claim 1, characterized in that The reaction temperature is 120-150° C. and the reaction time is 8-12 hours.

7. The method according to claim 1, characterized in that The mechanical alloying treatment adopts at least one of ball milling and extrusion.

8. The method according to claim 7, characterized in that The ball-to-material ratio of the ball mill is 1:2-3, the ball mill speed is 1000-3000 rpm, and the ball mill time is 15-30 min.

9. The method according to claim 7, characterized in that: The extrusion pressure is 80-300 MPa and the extrusion time is 15-30 min.

10. The method according to claim 1, characterized in that The pressure of the extrusion molding granulation is not less than 20MPa; and / or The heat treatment is carried out under an inert atmosphere at a temperature of 225 to 325° C. for a time of 30 to 120 min. Preferably, the inert gas content in the inert atmosphere is not less than 98 vol%.

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