Classification treatment and resource comprehensive utilization treatment method for municipal sludge incineration ash

Abstract

The invention discloses a municipal sludge incineration ash grading treatment and resource comprehensive utilization treatment method which comprises the following steps: firstly, drying municipal sludge, crushing the dried municipal sludge into clods with the diameter of 4-6mm, incinerating the clods in an incinerator, discharging residues, fly ash and flue gas, and respectively treating the residues, the fly ash and the flue gas; the residues are screened, and the residues with the particle size larger than or equal to 1 mm are recycled to serve as building materials; carrying out vitrification and micro-crystallization treatment on the residues with the particle sizes of less than 1mm and more than 0.1 mm to prepare microcrystalline glass; the method comprises the following steps: uniformly mixing residues and fly ash with the particle size of less than or equal to 0.1 mm and slag with the particle size of less than or equal to 0.1 mm to obtain mixed powder, carrying out plasma treatment, carrying out primary reduction by using ethanol, and carrying out secondary reduction by using mixed gas of ammonia gas and nitrogen to obtain an alloy material; the flue gas enters a combustion chamber containing a catalyst to be combusted again, residues and purified flue gas are discharged, the residues are returned to the screening step, and the purified flue gas is directly discharged after being cooled. By means of the method, graded treatment and resource comprehensive utilization of the municipal sludge incineration ash are achieved, particularly, alloy materials are obtained, metal can be further separated and purified, and metal recovery is achieved.

Description

Technical Field

[0001] The invention relates to a sludge resource treatment method, in particular to a municipal sludge incineration ash graded treatment resource comprehensive utilization treatment method. Background Art

[0002] With the development of economy and the improvement of people's living standards, the amount of urban sewage discharged is alarming, and sewage treatment will produce a large amount of urban sludge. Urban sludge has a high organic matter content, a strong odor, and is easy to rot and stink. At present, landfill and incineration are mainly used to treat urban sludge. Landfill will cause waste of land resources and further cause pollution to the surrounding environment. In comparison, incineration can achieve harmless treatment to a greater extent.

[0003] However, the incineration of municipal sewage sludge will produce a large amount of ash, which contains organic pollutants such as dioxins, as well as heavy metals such as zinc, lead, copper, and chromium in addition to silicon oxide, silicate, sulfate, etc., and is a highly hazardous waste. Therefore, it is very necessary to improve the existing municipal sewage sludge incineration process.

[0004] Patent CN103256608B discloses a sludge incineration method, which uses a sludge distributor to evenly add sludge to an incinerator, which is conducive to even distribution of sludge and efficient combustion; at the same time, it can prevent the combustion effect from being affected by the uneven supply of combustion-supporting air due to the imbalance of the material layer in the furnace and the uneven resistance of the incineration layer; the incinerator adopts bottom ash unloading and controls the residence time of the mud blocks in the furnace by the ash unloading speed, ensuring that the mud blocks stay in the furnace for more than 1 hour and that the organic matter content of the ash is less than 0.2%; the primary air from the air preheater is blown from the bottom of the incinerator to make the bottom of the furnace positive pressure and the top of the furnace slightly negative pressure. The sludge incineration method completely burns the sludge through high temperature and multiple incinerations, killing bacteria, pathogens and other substances in the sludge. The incineration ash generated during the incineration process can be used for brick making, cement production and other building materials, the waste heat generated by the incineration is also fully utilized, and the cost of the entire incineration method is low. However, the patent does not recycle the metals in the fly ash.

[0005] Patent CN1195879C discloses a method for recovering copper from metal sludge, which uses high-concentration metal sludge after precipitation as the object of treatment, uses high-temperature treatment to convert metal hydroxide into metal oxide, then uses coke to react with metal oxide to deoxidize the metal oxide to obtain metal, and finally performs metal refining. This patent uses metal sludge obtained from the treatment of metal ion-containing wastewater generated by circuit board production as the object of treatment, which is different from the composition of urban sludge. If it is copied to the treatment of urban sludge, there are still problems such as high dioxin content and high metal content in fly ash. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a method for the comprehensive utilization of urban sewage sludge incineration ash by graded treatment.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0009] (1) First, the municipal sludge is dried and crushed into mud blocks with a diameter of 4 to 6 mm, and then put into an incinerator for incineration, and the residue, fly ash and flue gas are discharged and respectively enter steps (2), (3) and (4);

[0010] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0011] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, plasma treating, performing a first reduction using ethanol, and then performing a second reduction using a mixed gas of ammonia and nitrogen to obtain an alloy material;

[0012] (4) The flue gas enters a combustion chamber containing a catalyst for re-combustion, and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling.

[0013] Preferably, in step (1), the drying is performed until the moisture content by weight is below 35%.

[0014] Preferably, in step (1), the incineration temperature is 850-950° C., and the incineration time is 60-90 minutes.

[0015] Preferably, in step (2), the process conditions for vitrification are: vitrification at 1300-1400° C. for 40-50 minutes.

[0016] Preferably, in step (2), the process conditions for microcrystallization are: first cool to 900-1000°C at 10-15°C / min, keep warm for 35-45 minutes, then cool to 500-600°C at 5-8°C / min, keep warm for 40-50 minutes, and naturally cool to room temperature.

[0017] Preferably, in step (3), the process conditions for plasma treatment are: air is used as the working gas, the air input pressure is 0.1-0.2 MPa, the power is 300-400 W, and the treatment time is 8-10 s.

[0018] Preferably, in step (3), the first reduction is carried out in a fixed bed reactor, and the process conditions are as follows: temperature 200-300°C, pressure 2-4 MPa, nitrogen is used as a carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol is 2-3 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 300-400:1.

[0019] Preferably, in step (3), a plasma reaction is used for the second reduction, the volume ratio of ammonia to nitrogen is 10-15:85-90, the input pressure of the mixed gas is 0.4-0.5 MPa, the power is 400-500 W, and the processing time is 40-50 s.

[0020] Preferably, in step (4), the catalyst is prepared by the following method, in parts by weight:

[0021] (A) First, 2 to 3 parts of ammonium metavanadate, 2 to 3 parts of ammonium molybdate and 0.8 to 1 part of indium nitrate are stirred and dissolved in 50 to 60 parts of a 6 to 8% monoethanolamine aqueous solution, and then 20 to 30 parts of titanium dioxide are added and stirred to obtain a premixed solution;

[0022] (B) Then, 4 to 5 parts of concentrated ammonia water with a mass concentration of 25 to 28% are slowly added to the premixed solution, stirred at room temperature for 6 to 7 hours, dried, calcined, and granulated to form granules.

[0023] Further preferably, in step (B), the concentrated ammonia solution is added for 30 minutes.

[0024] Further preferably, in step (B), the drying process conditions are: drying at 80-90° C. for 10-12 hours.

[0025] More preferably, in step (B), the calcination process conditions are: calcination at 600-650° C. for 6-7 hours.

[0026] More preferably, in step (B), the particle size is 40 to 50 meshes.

[0027] Preferably, in step (4), the process conditions for the re-combustion are: combustion at 150-200° C. for 20-30 minutes.

[0028] Beneficial effects of the present invention:

[0029] The present invention first dries the municipal sludge, crushes it into mud blocks with a diameter of 4 to 6 mm, and enters the incinerator for incineration, discharges the residue, fly ash and flue gas, and treats them separately. The residue is screened, and the residue with a particle size of ≥1 mm is recycled as a building material; the residue with a particle size of <1 mm and >0.1 mm is vitrified and microcrystallized to make microcrystalline glass; the residue with a particle size of ≤0.1 mm, fly ash and slag with a particle size of ≤0.1 mm are evenly mixed to obtain a mixed powder, plasma treated, and reduced for the first time using ethanol, and then reduced for the second time using a mixed gas of ammonia and nitrogen to obtain an alloy material; the flue gas enters a combustion chamber containing a catalyst for re-combustion, discharges the residue and purifies the flue gas, and the residue returns to the screening step, and the purified flue gas is directly discharged after cooling. The present invention realizes the comprehensive resource utilization of the graded treatment of the ash and slag from the incineration of municipal sludge, especially obtains alloy materials, and can further separate and purify metals, thereby realizing metal recovery.

[0030] The residue, fly ash and flue gas discharged from the incineration of urban sewage sludge are treated separately. After the residue is screened, the large particles can be used directly as building materials, the medium particles can be vitrified and microcrystallized to make microcrystalline glass, and the small particles can be combined with fly ash for metal recovery.

[0031] Since the flue gas contains pollutants such as dioxins, the present invention introduces a catalyst for re-combustion. The effective components of the catalyst are oxides of vanadium, molybdenum and indium, which can catalyze the decomposition of pollutants such as dioxins. Therefore, the flue gas can be directly discharged after cooling to avoid air pollution. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its contents.

[0033] Embodiment 1:

[0034] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0035] (1) First, the municipal sludge is dried to a moisture content of less than 35% by weight, crushed into lumps with a diameter of 4 mm, and placed in an incinerator for incineration at a temperature of 850° C. for 60 minutes, and the residue, fly ash and flue gas are discharged and placed in steps (2), (3) and (4) respectively;

[0036] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0037] The process conditions of vitrification are: vitrification at 1300°C for 40 minutes;

[0038] Preferably, in step (2), the process conditions for microcrystallization are: firstly cooling to 900°C at 10°C / min, keeping the temperature for 35 minutes, then cooling to 500°C at 5°C / min, keeping the temperature for 40 minutes, and naturally cooling to room temperature;

[0039] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, plasma treating, performing a first reduction using ethanol, and then performing a second reduction using a mixed gas of ammonia and nitrogen to obtain an alloy material;

[0040] The process conditions of plasma treatment were: air as working gas, air input pressure of 0.1 MPa, power of 300 W, and treatment time of 8 s;

[0041] The first reduction was carried out in a fixed bed reactor under the following process conditions: temperature 200 °C, pressure 2 MPa, nitrogen as carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol was 2 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 300:1;

[0042] The second reduction was carried out by plasma reaction, with a volume ratio of ammonia to nitrogen of 10:90, an input pressure of the mixed gas of 0.4 MPa, a power of 400 W, and a processing time of 40 s.

[0043] (4) The flue gas enters a combustion chamber containing a catalyst for further combustion (burning at 150°C for 20 minutes), and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling;

[0044] The catalyst is prepared by the following method:

[0045] (A) First, 2 kg of ammonium metavanadate, 2 kg of ammonium molybdate and 0.8 kg of indium nitrate were stirred and dissolved in 50 kg of a 6% monoethanolamine aqueous solution, and then 20 kg of titanium dioxide was added and stirred to obtain a premixed solution;

[0046] (B) then slowly adding 4 kg of 25% concentrated ammonia water to the premixed solution, stirring at room temperature for 6 hours, drying, calcining, and granulating into particles with a particle size of 40 mesh;

[0047] In step (B), the concentrated ammonia solution is added for 30 minutes;

[0048] The drying process conditions are: drying at 80°C for 10 hours;

[0049] The calcination process conditions are: calcination at 600°C for 6 hours.

[0050] Embodiment 2:

[0051] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0052] (1) First, the municipal sludge is dried to a moisture content of less than 35% by weight, crushed into lumps with a diameter of 6 mm, and placed in an incinerator for incineration at a temperature of 950° C. for 90 minutes, and the residue, fly ash and flue gas are discharged and placed in steps (2), (3) and (4) respectively;

[0053] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0054] The process conditions of vitrification are: vitrification at 1400°C for 50 minutes;

[0055] Preferably, in step (2), the process conditions for microcrystallization are: firstly cooling to 1000°C at 15°C / min, keeping warm for 45 minutes, then cooling to 600°C at 8°C / min, keeping warm for 50 minutes, and naturally cooling to room temperature;

[0056] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, plasma treating, performing a first reduction using ethanol, and then performing a second reduction using a mixed gas of ammonia and nitrogen to obtain an alloy material;

[0057] The process conditions of plasma treatment were: air as working gas, air input pressure of 0.2 MPa, power of 400 W, and treatment time of 10 s;

[0058] The first reduction was carried out in a fixed bed reactor under the following process conditions: temperature 300°C, pressure 4 MPa, nitrogen as carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol was 3 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 400:1;

[0059] The second reduction was carried out by plasma reaction, with a volume ratio of ammonia to nitrogen of 15:85, an input pressure of the mixed gas of 0.5 MPa, a power of 500 W, and a processing time of 50 s.

[0060] (4) The flue gas enters a combustion chamber containing a catalyst for further combustion (combustion at 200°C for 30 minutes), and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling;

[0061] The catalyst is prepared by the following method:

[0062] (A) First, 3 kg of ammonium metavanadate, 3 kg of ammonium molybdate and 1 kg of indium nitrate were stirred and dissolved in 60 kg of 8% monoethanolamine aqueous solution, and then 30 kg of titanium dioxide was added and stirred to obtain a premixed solution;

[0063] (B) then slowly adding 5 kg of 28% concentrated ammonia water to the premixed solution, stirring at room temperature for 7 hours, drying, calcining, and granulating into particles with a particle size of 50 mesh;

[0064] In step (B), the concentrated ammonia solution is added for 30 minutes;

[0065] The drying process conditions are: drying at 90°C for 12 hours;

[0066] The calcination process conditions are: calcination at 650°C for 7 hours.

[0067] Embodiment 3:

[0068] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0069] (1) First, the municipal sludge is dried to a moisture content of less than 35% by weight, crushed into lumps with a diameter of 4 mm, and placed in an incinerator for incineration at a temperature of 950° C. for 60 minutes, and the residue, fly ash and flue gas are discharged and placed in steps (2), (3) and (4) respectively;

[0070] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0071] The process conditions of vitrification are: vitrification at 1400°C for 40 minutes;

[0072] Preferably, in step (2), the process conditions for microcrystallization are: firstly cooling to 900°C at 15°C / min, keeping at that temperature for 45 minutes, then cooling to 600°C at 5°C / min, keeping at that temperature for 40 minutes, and naturally cooling to room temperature;

[0073] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, plasma treating, performing a first reduction using ethanol, and then performing a second reduction using a mixed gas of ammonia and nitrogen to obtain an alloy material;

[0074] The process conditions of plasma treatment were: air as working gas, air input pressure of 0.2 MPa, power of 300 W, and treatment time of 10 s;

[0075] The first reduction was carried out in a fixed bed reactor under the following process conditions: temperature 200 °C, pressure 4 MPa, nitrogen as carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol was 2 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 400:1;

[0076] The second reduction was carried out by plasma reaction, with a volume ratio of ammonia to nitrogen of 10:90, an input pressure of the mixed gas of 0.4 MPa, a power of 500 W, and a processing time of 40 s.

[0077] (4) The flue gas enters a combustion chamber containing a catalyst for further combustion (burning at 200°C for 20 minutes), and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling;

[0078] The catalyst is prepared by the following method:

[0079] (A) First, 3 kg of ammonium metavanadate, 2 kg of ammonium molybdate and 1 kg of indium nitrate were stirred and dissolved in 50 kg of 8% monoethanolamine aqueous solution, and then 20 kg of titanium dioxide was added and stirred to obtain a premixed solution;

[0080] (B) then slowly adding 5 kg of 25% concentrated ammonia water to the premixed solution, stirring at room temperature for 7 hours, drying, calcining, and granulating into particles with a particle size of 40 mesh;

[0081] In step (B), the concentrated ammonia solution is added for 30 minutes;

[0082] The drying process conditions are: drying at 90°C for 10 hours;

[0083] The calcination process conditions are: calcination at 650°C for 6 hours.

[0084] Embodiment 4:

[0085] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0086] (1) First, the municipal sludge is dried to a moisture content of less than 35% by weight, crushed into lumps with a diameter of 5 mm, and placed in an incinerator for incineration at a temperature of 900° C. for 80 minutes, and the residue, fly ash and flue gas are discharged and placed in steps (2), (3) and (4) respectively;

[0087] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0088] The process conditions for vitrification are: vitrification at 1350°C for 45 minutes;

[0089] Preferably, in step (2), the process conditions for microcrystallization are: firstly cooling to 950°C at 12°C / min, keeping the temperature for 40 minutes, then cooling to 550°C at 6°C / min, keeping the temperature for 45 minutes, and naturally cooling to room temperature;

[0090] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, plasma treating, performing a first reduction using ethanol, and then performing a second reduction using a mixed gas of ammonia and nitrogen to obtain an alloy material;

[0091] The process conditions of plasma treatment were: air as working gas, air input pressure of 0.1 MPa, power of 400 W, and treatment time of 9 s;

[0092] The first reduction was carried out in a fixed bed reactor under the following process conditions: temperature 250°C, pressure 3 MPa, nitrogen as carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol was 2 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 350:1;

[0093] The second reduction was carried out by plasma reaction, with a volume ratio of ammonia to nitrogen of 12:88, an input pressure of the mixed gas of 0.5 MPa, a power of 500 W, and a processing time of 45 s.

[0094] (4) The flue gas enters a combustion chamber containing a catalyst for further combustion (burning at 180°C for 25 minutes), and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling;

[0095] The catalyst is prepared by the following method:

[0096] (A) First, 2.5 kg of ammonium metavanadate, 2.5 kg of ammonium molybdate and 0.9 kg of indium nitrate were stirred and dissolved in 55 kg of a 7% monoethanolamine aqueous solution, and then 25 kg of titanium dioxide was added and stirred to obtain a premixed solution;

[0097] (B) then slowly adding 4.5 kg of 26% concentrated ammonia water to the premixed solution, stirring at room temperature for 6 hours, drying, calcining, and granulating into particles with a particle size of 50 mesh;

[0098] In step (B), the concentrated ammonia solution is added for 30 minutes;

[0099] The drying process conditions were: drying at 85°C for 11 hours;

[0100] The calcination process conditions are: calcination at 620°C for 6 hours.

[0101] Comparative Example 1

[0102] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0103] (1) First, the municipal sludge is dried to a moisture content of less than 35% by weight, crushed into lumps with a diameter of 4 mm, and placed in an incinerator for incineration at a temperature of 850° C. for 60 minutes, and the residue, fly ash and flue gas are discharged and placed in steps (2), (3) and (4) respectively;

[0104] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0105] The process conditions of vitrification are: vitrification at 1300°C for 40 minutes;

[0106] Preferably, in step (2), the process conditions for microcrystallization are: firstly cooling to 900°C at 10°C / min, keeping the temperature for 35 minutes, then cooling to 500°C at 5°C / min, keeping the temperature for 40 minutes, and naturally cooling to room temperature;

[0107] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, treating it with plasma, and reducing it with ethanol to obtain an alloy material;

[0108] The process conditions of plasma treatment were: air as working gas, air input pressure of 0.1 MPa, power of 300 W, and treatment time of 8 s;

[0109] The reduction was carried out in a fixed bed reactor under the following process conditions: temperature 200°C, pressure 2 MPa, nitrogen as carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol was 2 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 300:1;

[0110] (4) The flue gas enters a combustion chamber containing a catalyst for further combustion (burning at 150°C for 20 minutes), and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling;

[0111] The catalyst is prepared by the following method:

[0112] (A) First, 2 kg of ammonium metavanadate, 2 kg of ammonium molybdate and 0.8 kg of indium nitrate were stirred and dissolved in 50 kg of a 6% monoethanolamine aqueous solution, and then 20 kg of titanium dioxide was added and stirred to obtain a premixed solution;

[0113] (B) then slowly adding 4 kg of 25% concentrated ammonia water to the premixed solution, stirring at room temperature for 6 hours, drying, calcining, and granulating into particles with a particle size of 40 mesh;

[0114] In step (B), the concentrated ammonia solution is added for 30 minutes;

[0115] The drying process conditions are: drying at 80°C for 10 hours;

[0116] The calcination process conditions are: calcination at 600°C for 6 hours.

[0117] Comparative Example 2

[0118] A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, the specific steps are as follows:

[0119] (1) First, the municipal sludge is dried to a moisture content of less than 35% by weight, crushed into lumps with a diameter of 4 mm, and placed in an incinerator for incineration at a temperature of 850° C. for 60 minutes, and the residue, fly ash and flue gas are discharged and placed in steps (2), (3) and (4) respectively;

[0120] (2) Screening the residue, recycling the residue with a particle size of ≥1 mm as building materials; vitrifying and microcrystallizing the residue with a particle size of <1 mm and >0.1 mm to make microcrystalline glass; and entering step (3) the residue with a particle size of ≤0.1 mm;

[0121] The process conditions of vitrification are: vitrification at 1300°C for 40 minutes;

[0122] Preferably, in step (2), the process conditions for microcrystallization are: firstly cooling to 900°C at 10°C / min, keeping the temperature for 35 minutes, then cooling to 500°C at 5°C / min, keeping the temperature for 40 minutes, and naturally cooling to room temperature;

[0123] (3) mixing fly ash and slag with a particle size of ≤0.1 mm to obtain a mixed powder, plasma treating, performing a first reduction using ethanol, and then performing a second reduction using a mixed gas of ammonia and nitrogen to obtain an alloy material;

[0124] The process conditions of plasma treatment were: air as working gas, air input pressure of 0.1 MPa, power of 300 W, and treatment time of 8 s;

[0125] The first reduction was carried out in a fixed bed reactor under the following process conditions: temperature 200 °C, pressure 2 MPa, nitrogen as carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol was 2 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 300:1;

[0126] The second reduction was carried out by plasma reaction, with a volume ratio of ammonia to nitrogen of 10:90, an input pressure of the mixed gas of 0.4 MPa, a power of 400 W, and a processing time of 40 s.

[0127] (4) The flue gas enters a combustion chamber containing a catalyst for further combustion (burning at 150°C for 20 minutes), and the residue and purified flue gas are discharged. The residue is returned to step (2), and the purified flue gas is directly discharged after cooling;

[0128] The catalyst is prepared by the following method:

[0129] (A) First, 2 kg of ammonium metavanadate and 2 kg of ammonium molybdate were stirred and dissolved in 50 kg of a 6% monoethanolamine aqueous solution, and then 20 kg of titanium dioxide was added and stirred to obtain a premixed solution;

[0130] (B) then slowly adding 4 kg of 25% concentrated ammonia water to the premixed solution, stirring at room temperature for 6 hours, drying, calcining, and granulating into particles with a particle size of 40 mesh;

[0131] In step (B), the concentrated ammonia solution is added for 30 minutes;

[0132] The drying process conditions are: drying at 80°C for 10 hours;

[0133] The calcination process conditions are: calcination at 600°C for 6 hours.

[0134] Test example

[0135] For ease of comparison, the methods of Examples 1 to 4 and Comparative Examples 1 and 2 were used to treat municipal sludge from the same source. The sludge contained metal components such as copper and nickel, which existed in an oxidized state in fly ash and slag. The contents of reduced copper and nickel in the alloy materials obtained in Examples 1 to 4 and Comparative Example 1 were tested, and the reduction rates of copper oxide and nickel oxide (by mass) were calculated. The results are shown in Table 1.

[0136] The components of the purified flue gas discharged from Examples 1 to 4 and Comparative Example 2 were tested respectively, and the dioxin content was tested with reference to GB / T18485-2014 "Standard for Pollution Control of Incineration of Domestic Waste". The results are shown in Table 2.

[0137] Table 1. Comparison of reduction rates of copper oxide and nickel oxide

[0138] Copper oxide reduction rate (%) Nickel oxide reduction rate (%) Example 1 95.4 95.3 Example 2 95.6 95.6 Example 3 95.9 95.8 Example 4 96.4 96.1 Comparative Example 1 88.3 87.4

[0139] Table 2. Comparison of dioxin content in purified flue gas

[0140]

[0141]

[0142] It can be seen from Table 1 and Table 2 that the alloy materials obtained in Examples 1 to 4 fully reduce the metal oxides in the small-particle slag and fly ash after sludge incineration, and obtain alloy materials with high reduced metal content, thereby realizing metal recovery, and the content of dioxins in the purified flue gas is low, which can be directly discharged without pollution, thus realizing the comprehensive resource utilization of urban sludge incineration ash and slag graded treatment.

[0143] In Comparative Example 1, the second reduction was omitted, and the reduction rate of metal oxides was low, indicating that the reduction was not sufficient and the metal resource utilization was affected; in Comparative Example 2, indium nitrate was omitted when preparing the catalyst, and the content of dioxins in the flue gas increased, indicating that the specific catalyst of the present invention has a better removal effect on dioxins in the flue gas.

[0144] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for comprehensive resource utilization of municipal sewage sludge incineration ash by graded treatment, characterized in that: The specific steps are as follows: (1) First, the municipal sludge is dried and crushed into mud blocks with a diameter of 4 to 6 mm, and then put into an incinerator for incineration, and the residue, fly ash and flue gas are discharged and enter steps (2), (3) and (4) respectively; (2) Screening the residues, and recycling the residues with a particle size ≥ 1 mm as building materials; The residue with a particle size of less than 1 mm and greater than 0.1 mm is vitrified and microcrystallized to produce microcrystalline glass; the residue with a particle size of ≤ 0.1 mm enters step (3); (3) The fly ash and the slag with a particle size of ≤0.1 mm are uniformly mixed to obtain a mixed powder, and the mixed powder is treated with plasma, and the mixed powder is reduced for the first time using ethanol, and then reduced for the second time using a mixed gas of ammonia and nitrogen to obtain an alloy material; (4) The flue gas enters a combustion chamber containing a catalyst for re-combustion, and the residue and purified flue gas are discharged. The residue returns to step (2), and the purified flue gas is directly discharged after cooling.

2. The method according to claim 1, characterized in that In step (1), the mixture is dried until the moisture content is less than 35%.

3. The method according to claim 1, characterized in that In step (1), the incineration temperature is 850-950°C and the incineration time is 60-90 minutes.

4. The method according to claim 1, characterized in that In step (2), the process conditions for vitrification are: vitrification at 1300-1400° C. for 40-50 minutes.

5. The method according to claim 1, characterized in that In step (2), the process conditions for microcrystallization are: first, cool down to 900-1000°C at a rate of 10-15°C / min, keep warm for 35-45 minutes, then cool down to 500-600°C at a rate of 5-8°C / min, keep warm for 40-50 minutes, and cool naturally to room temperature.

6. The method according to claim 1, characterized in that In step (3), the process conditions of plasma treatment are: air is used as the working gas, the air input pressure is 0.1-0.2 MPa, the power is 300-400 W, and the treatment time is 8-10 s.

7. The method according to claim 1, characterized in that In step (3), the first reduction is carried out in a fixed bed reactor, and the process conditions are as follows: temperature 200-300°C, pressure 2-4 MPa, nitrogen is used as a carrier gas to carry ethanol into the fixed bed reactor, and the liquid space velocity of ethanol is 2-3 mL / (h·g cat ), the volume ratio of nitrogen to ethanol is 300-400:

1.

8. The method according to claim 1, characterized in that In step (3), a plasma reaction is used for the second reduction, the volume ratio of ammonia to nitrogen is 10-15:85-90, the input pressure of the mixed gas is 0.4-0.5 MPa, the power is 400-500 W, and the processing time is 40-50 s.

9. The method according to claim 1, characterized in that: In step (4), the catalyst is prepared by the following method, in parts by weight: (A) First, 2 to 3 parts of ammonium metavanadate, 2 to 3 parts of ammonium molybdate and 0.8 to 1 part of indium nitrate are stirred and dissolved in 50 to 60 parts of a 6 to 8% monoethanolamine aqueous solution, and then 20 to 30 parts of titanium dioxide are added and stirred to obtain a premixed solution; (B) Then, 4 to 5 parts of concentrated ammonia water with a mass concentration of 25 to 28% are slowly added to the premixed solution, stirred at room temperature for 6 to 7 hours, dried, calcined, and granulated to form granules.

10. The method according to claim 1, characterized in that In step (4), the process conditions for the re-combustion are: combustion at 150-200° C. for 20-30 minutes.

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