Recovery of potassium dihydrogen phosphate, silicon dioxide, copper electrode, zinc, nickel-chromium alloy and high-temperature ceramic refractory material from municipal sludge incineration ash and its recovery manufacturing method

Abstract

The application belongs to the technical field of urban domestic sludge incineration ash treatment process, and directly attacks and destroys the silicon-oxygen lattice of silicate by using an activator to make the silicon-oxygen bond break and establish a new silicon-fluorine bond, and a large part of useful resources and heavy metals are released in the process of breaking the old covalent bond and forming a new covalent bond, then the chelating agent is used for leaching, and phosphorus, silicon, iron, copper, zinc, chromium and nickel are comprehensively recovered through post-treatment, the application recovers instant potassium dihydrogen phosphate, the fertilizer is strong and is a phosphorus-potassium dual-purpose fertilizer, is suitable for various planting and urban vertical hydroponics, silicon dioxide is recovered, copper electrodes, metal zinc and nickel-chromium alloy are obtained by using the electrodeposition method, and the leaching residue is made into high-temperature ceramic refractory heat insulation material with low thermal conductivity. The unique design of the application makes the main reagents, the activator and the leaching agent, can be recycled, which saves resources and greatly saves costs. There is no sewage and waste gas emission, and the environment is protected while the value is created.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of municipal sewage sludge incineration ash treatment, in particular to a method for recovering potassium dihydrogen phosphate, silicon dioxide, copper electrode, zinc, nickel-chromium alloy and high-temperature ceramic refractory material from municipal sewage sludge incineration ash and manufacturing the same. BACKGROUND

[0002] High-quality municipal sewage sludge contains rich organic matter and nitrogen, phosphorus and potassium, and can be used for soil improvement and organic fertilizer. However, the quality of municipal sewage sludge is uneven, and many of them contain a large amount of toxic heavy metals, which cannot be used for soil improvement and organic fertilizer. Therefore, people add chelating agents, precipitants and solidifying agents to the municipal sewage sludge, and after meeting the national standard GB16889-2008, they are transported to the landfill site for landfill. This is not a commercially profitable thing, and it is not worth the effort. With the advancement of scientific research projects and the progress of technology, some new technologies have emerged to develop municipal sewage sludge waste into resources. For example, municipal sewage sludge is made into building materials, used for road foundation, building bricks, lightweight materials, etc. by adding some stabilizers, binders and even some other treated hazardous wastes, which have economic value. Municipal sewage sludge anaerobic fermentation technology has also begun, producing biogas, which can be used for heating and has economic value. However, municipal sewage sludge anaerobic fermentation also has residues. Therefore, people add chelating agents, precipitants and solidifying agents to the municipal sewage sludge anaerobic fermentation residues, and after meeting the national standard GB16889-2008, they are transported to the landfill site for landfill. This is also not a commercially valuable thing, and it is not worth the effort. With the gradual maturity of municipal waste incineration technology, it has driven the research and development of municipal sewage sludge and municipal sewage sludge anaerobic fermentation residue incineration technology and the establishment of factory production processes. Municipal sewage sludge and municipal sewage sludge anaerobic fermentation residue incineration can produce heat energy, generate electricity and provide heating, and the volume of sludge incineration ash is only one tenth of the volume before incineration. After chelation, stabilization and solidification, landfill is greatly reduced, saving land and resources. However, the heavy metal content in sludge incineration ash is several times higher than that in sludge itself, increasing the difficulty and cost of chelation, stabilization and solidification. In addition, sludge incineration ash contains a large amount of non-renewable resources of phosphorus, which has attracted people's attention.

[0003] CN111792636B, Tongji University, Zhang Hua, et al. proposed a method for recovering vivianite from sludge incineration ash, using acid leaching of phosphorus, and then using water sludge and other adsorbents to enrich the leached phosphorus, and adding ferrous ions to form artificial vivianite powder. However, vivianite ferrous phosphate is insoluble in water and has no fertility. CN116621231A, Zhejiang University, Wang Fei, et al. proposed a method for recovering phosphorus, aluminum and iron from sludge incineration fly ash and building material utilization, acid leaching, preparing iron sulfate, aluminum hydroxide and hydroxyapatite. However, hydroxyapatite is not soluble and has no fertility. CN105772484B, Wuhan Textile University, Li Jinping, et al. proposed a harmless treatment technology for municipal sludge incineration ash and a method for recovering phosphorus compounds, which uses acid and alkali combined leaching of phosphorus and precipitates in the form of magnesium ammonium phosphate. However, magnesium ammonium phosphate is also difficult to dissolve and has no fertility. CN106430136B, Zhang Guomin, et al. proposed a method for recovering phosphorus and removing heavy metals from sludge incineration ash, which also uses acid leaching of phosphorus and heavy metals, and uses sulfide precipitation to separate heavy metals, and then synthesizes phosphorus in the form of calcium phosphate. Calcium phosphate is not soluble and has no fertility. CN113401887B, Hubei Yunxiang Poly Energy New Energy Technology Co., Ltd., Chen Yingying, proposed a method for preparing iron phosphate from municipal sludge incineration ash and battery-grade iron phosphate, which leaches phosphorus, iron, aluminum and heavy metals with acid, adjusts the pH value to 6 to remove iron and aluminum impurities, adds a decontamination agent to remove magnesium and calcium impurities, adds a precipitant to remove heavy metal ions, and then adds an oxidizing agent and ferrous ions to produce high-purity iron phosphate for lithium-ion battery anode precursors. This method has some meaning, but the inventors may not have noticed that although the phosphorus leaching rate is as high as 97%, the iron ions are removed in the form of iron phosphate and aluminum hydroxide when the pH value is adjusted to 6 to remove iron and aluminum impurities, and the content of iron in sludge incineration ash is very high, with an iron: phosphorus weight ratio of 1:1.85. After the iron is removed, the theoretical calculation shows that the yield of high-purity iron phosphate obtained is less than 45%.

[0004] In summary, we believe that the common problems and pain points of existing patents and documents using municipal sludge incineration ash are: 1) The phosphorus fertilizer produced by leaching has no fertility in reality, although it is called slow-release fertilizer. 2) The acid method is the same everywhere and has no new ideas. 3) Digestion of large amounts of acid is not renewable and consumes many resources. 4) A large amount of acid waste liquid is generated, which requires resources to be treated. 5) Only phosphorus is considered, and other useful resources, including iron, aluminum and silicon, are not taken into account. 6) Heavy metals are avoided like a tiger and are not utilized. The generated heavy metal-containing hazardous waste also needs to be landfilled. 7) The residue produced after acid leaching is difficult to recycle and is mostly destined for landfill.

[0005] In view of this, the present application is a new development, and comprehensively solves all the problems of the existing patents and documents using municipal sludge incineration ash. This application abandons the traditional acid leaching method, and uses an activator to directly attack and destroy the silicon-oxygen lattice of silicate to break the silicon-oxygen bond and establish a new silicon-fluorine bond. In the process of breaking the old covalent bond and forming a new covalent bond, most of the useful resources and heavy metals are released. Then, a chelating agent is used for leaching, and after treatment, phosphorus, silicon, iron, copper, zinc, chromium and nickel are fully recovered, with recovery rates of 99%, 100%, 90%, 99%, 94%, 81% and 83% respectively, far exceeding the documents. Basically, the documents in the field can only recover insoluble or hardly soluble phosphate, which is called slow-release fertilizer. In fact, its fertility is very poor and is not suitable for urban vertical hydroponics. This application recovers fast- dissolving potassium dihydrogen phosphate, which has strong fertility and is a phosphorus-potassium dual fertilizer, suitable for various plantings and urban vertical hydroponics. This application recovers silicon dioxide, and uses electrodeposition to recover copper electrodes, metal zinc and nickel-chromium alloy, which has not been reported in the documents. The leaching residue is made into high-temperature ceramic refractory heat- insulating materials with low thermal conductivity, which has much higher economic value than ordinary foundation building materials, bricks, cement, etc. The unique design of this application allows the main reagents, activator and leaching agent, to be recycled, saving resources and greatly reducing costs. There is no sewage and waste gas emission, creating value while protecting the environment. SUMMARY

[0006] To solve the defects and problems of the existing technology of municipal sludge incineration ash, a method for recovering potassium dihydrogen phosphate, silicon dioxide, metal copper electrode, metal zinc, nickel-chromium alloy and high-temperature ceramic refractory material from municipal sludge incineration ash and a manufacturing method thereof are provided.

[0007] The technical scheme adopted by the present application to solve its technical problems is: the method for recovering potassium dihydrogen phosphate, silicon dioxide, metal copper electrode, metal zinc, nickel-chromium alloy and high-temperature ceramic refractory material from municipal sludge incineration ash and a manufacturing method thereof of the present application uses an activator to directly attack and destroy the silicon-oxygen lattice of silicate to break the silicon-oxygen bond and establish a new silicon-fluorine bond, forming fluorosilicate. In the process of breaking the old covalent bond and forming a new covalent bond, most of the useful resources and heavy metals are released. Then, a chelating agent is used for leaching, and after treatment, phosphorus, silicon, iron, copper, zinc, chromium and nickel are fully recovered, and the residue is made into a low-thermal-conductivity heat- insulating material. The recovery products include potassium dihydrogen phosphate, silicon dioxide, iron sulfate, aluminum sulfate, copper electrode, metal zinc, nickel-chromium alloy and low-thermal-conductivity porous ceramic.

[0008] The process is as follows:

[0009] A. Activated incineration ash

[0010] Direct attack of the silicate siloxane lattice of municipal sewage incineration ash with activators to break the siloxane bonds and create new silicon-fluorine bonds to form fluosilicates, releasing most of the useful resources and heavy metals in the process of breaking old covalent bonds and forming new covalent bonds; Put the sewage incineration ash (such as 1000 grams) in a container (such as a ceramic crucible), add the activator potassium fluoride, sodium fluoride, ammonium hydrogen fluoride or ammonium fluoride according to the weight ratio of activator / incineration ash 0.1:1-3:1, mix evenly, and then place it in an oven and heat to 100-180℃ for 1-3 hours. After the reaction is completed, the incineration activated ash is obtained; B, chelate leaching

[0011] Fast route: The above activated ash is transferred to a PTFE reaction container, 2-20 liters of 1-9% w / v EDTA (ethylenediaminetetraacetic acid) extraction solution is added to the activated incineration ash, stirred for 5 minutes, the stirring speed is 200-300 rpm, the pH value can be adjusted to slightly acidic with sulfuric acid, nitric acid or hydrochloric acid, the pH range is 3.1-4.6, and then stirred for another 5 minutes, the stirring speed is 200-300 rpm. Put the PTFE reaction container into a high-pressure reaction kettle without stirring, and react at 120-200℃ for 1-3 hours to leach phosphates, fluorosilicates, iron ions, aluminum ions, and most of the heavy metal ions into the solution. After the solution is cooled, the solid-liquid mixture after leaching is subjected to solid-liquid separation to obtain filtrate one and residue one, and the residue amount is 50-60% wt.;

[0012] Energy-saving route: The above activated ash is transferred to an inert reaction container, 2-20 liters of 1-9% w / v EDTA (ethylenediaminetetraacetic acid) extraction solution is added to the activated incineration ash, stirred for 5 minutes, the stirring speed is 200-300 rpm, the pH value can be adjusted to slightly acidic with sulfuric acid, nitric acid or hydrochloric acid, the pH range is 3.1-4.6, and then stirred for another 18-24 hours, the stirring speed is 800-1000 rpm. Leach phosphates, fluorosilicates, iron ions, aluminum ions, and most of the heavy metal ions into the solution. The solid-liquid mixture after leaching is subjected to solid-liquid separation to obtain filtrate one and residue one, and the residue amount is 50-60% wt.;

[0013] C, residue one post-treatment

[0014] Take the dry residue one after extraction, according to EDS analysis, the main components are calcium aluminate and quartz, add bauxite and kaolin, mix evenly according to the weight ratio of residue one:bauxite:kaolin 1:0.5-1.5:0.5-1.5, and then calcine in a super-high-temperature muffle furnace at 1300-1400℃ for 1-3 hours to obtain a high-temperature ceramic refractory heat insulation material with low thermal conductivity;

[0015] D, filtrate one post-treatment

[0016] To 1.5 L of filtrate one, 90-100 grams of potassium chloride or 70-80 grams of sodium chloride is added, stirred for 1 minute at 100-200 rpm, aged for 10 minutes to produce a precipitate of potassium fluosilicate or sodium fluosilicate, solid-liquid separation produces filtrate two and residue two (fluosilicate), to filtrate two, sodium hydroxide is added to a pH of 4-5, stirred for 1 minute at 100-200 rpm, aged for 10 minutes to produce a precipitate of iron phosphate, affected by the chelating leaching agent, the first leaching of iron recovery rate is only 50-60%, solid-liquid separation produces filtrate three and residue three (iron phosphate), to filtrate three, 27-54 grams of calcium chloride is added to a pH of 6, then calcium hydroxide is added to a pH of 6, stirred for 1 minute at 100-200 rpm, aged for 10 minutes to produce a white precipitate of calcium phosphate, affected by the chelating leaching agent, the first leaching of phosphoric acid recovery rate is only 50-60%, solid-liquid separation produces filtrate four and residue four (calcium phosphate), to filtrate four, NaOH is added to a pH of 7-9, stirred for 1 minute at 100-200 rpm, aged for 10 minutes to produce a precipitate of aluminum hydroxide (not aluminum phosphate), solid-liquid separation produces filtrate five and residue five (aluminum hydroxide), filtrate five is electrodeposited on a copper or carbon electrode at a voltage of -2V to -4V for 30 minutes at 200-300 rpm to obtain a copper electrode, which is widely used for copper electroplating and electric spark machining, the copper recovery rate reaches 99%, electrolyte solution solid-liquid separation produces filtrate six and residue six - a mixed precipitate of nickel hydroxide, zinc hydroxide, and chromium hydroxide, to 10 grams of dry residue three (iron phosphate), 50-80 ml of 1-2M potassium hydroxide solution is added, stirred for 30 minutes at 300-500 rpm to produce a precipitate of iron hydroxide and a potassium dihydrogen phosphate solution, solid-liquid separation of the electrolyte produces filtrate seven and residue seven (iron hydroxide), the potassium dihydrogen phosphate solution of filtrate seven is heated and evaporated to dryness, then purified to obtain solid potassium dihydrogen phosphate, which can be used as an agricultural, forestry, horticulture, and urban vertical hydroponic instant phosphorus-potassium binary fertilizer, to 10 grams of dry residue four (calcium phosphate), 50-80 ml of 1-2M potassium hydroxide solution is added, stirred for 30 minutes at 300-500 rpm to produce a precipitate of calcium hydroxide and a potassium dihydrogen phosphate solution, solid-liquid separation of the electrolyte produces filtrate eight and residue eight (calcium hydroxide), filtrate eight contains a small amount of calcium ions, a little oxalic acid can be added to precipitate and remove, solid-liquid separation of the electrolyte produces filtrate nine and residue nine (calcium oxalate), dry residue eight calcium hydroxide becomes a product of calcium hydroxide, which can be used for the treatment of filtrate three.The filtrate seven and filtrate nine potassium dihydrogen phosphate solution is heated to evaporate dry, and then purified to obtain solid potassium dihydrogen phosphate, which can be used as agriculture, forestry, horticulture and urban vertical hydroponic instant phosphorus potassium binary fertilizer, to 1 gram of dry residue seven ferric hydroxide precipitate, add 2-2.5 grams of concentrated sulfuric acid, stirring speed 100-200 rpm, stirring for 10 minutes, dry purification of solid state iron sulfate, which can be used as water treatment flocculant, to 1 gram of dry residue five aluminum hydroxide precipitate, add 2-3 grams of concentrated sulfuric acid, stirring speed 100-200 rpm, stirring for 10 minutes, dry purification of solid state aluminum sulfate, which can be used as water treatment flocculant, to 1 gram of dry residue six mixed nickel hydroxide, zinc hydroxide, chromium hydroxide precipitate, add 20-50 ml of 0.2-1 M sodium hydroxide solution, stirring for 10 minutes, stirring speed 300-500 rpm, dissolve zinc hydroxide, solid-liquid separation to obtain filtrate ten and residue ten-nickel hydroxide and chromium hydroxide mixture, dry, 1 gram of residue ten-nickel hydroxide and chromium hydroxide mixture is heated to 600-800 ℃ in air atmosphere first into a mixture of nickel oxide, chromium oxide, add 0.2-0.5 grams of carbon powder, mix evenly, then heated to 600-800 ℃ in nitrogen atmosphere into nickel-chromium alloy, to obtain high purity nickel-chromium alloy, which is widely used as heating wire material, nickel-chromium recovery rate is as high as 83% and 81%, to the foregoing filtrate ten-dissolved zinc hydroxide solution, add sulfuric acid to adjust the pH to 6-8, stirring for 1 minute, stirring speed 100-200 rpm, aging for 10 minutes, generate zinc hydroxide precipitate, solid-liquid separation to obtain filtrate eleven and residue eleven(zinc hydroxide). 1 gram of dry residue eleven zinc hydroxide is heated to 600-800 ℃ in air atmosphere first into zinc oxide, add 0.3-0.5 grams of carbon powder, mix evenly, then heated to 600-800 ℃ in nitrogen atmosphere into metallic zinc, zinc recovery rate is as high as 94%.

[0017] E, activation agent regeneration cycle

[0018] To dry residue two solid potassium or sodium fluorosilicate (such as 5 grams), add 3.0-4.0 ml of 25%wt. ammonia water, stirring for 2-5 hours, stirring speed 300-500 rpm, generate white precipitate silicon dioxide, solid-liquid separation to obtain filtrate twelve and residue twelve(silicon dioxide), dry residue twelve to product silicon dioxide, evaporate filtrate twelve to precipitate sodium fluoride or potassium fluoride, solid-liquid separation to obtain filtrate thirteen and residue thirteen(sodium fluoride or potassium fluoride), dry residue thirteen to obtain product sodium fluoride or potassium fluoride, which is an activator, recycled use, evaporate filtrate thirteen to dry, to obtain product ammonium fluoride, product ammonium fluoride is also an activator, recycled use;

[0019] F, chelating leaching agent regeneration cycle

[0020] The filtrate contains the leaching agent, most of the leaching agent is free in unchelated state, and a small part of the leaching agent is chelated with iron, but does not affect the recycling, the recovery rate of phosphoric acid and iron in the first leaching is only 50-60%, and the activated incineration ash is added into the filtrate, and the phosphoric acid and iron are leached according to steps B-F, and the recovery rate of the phosphoric acid and iron in the second and subsequent leaching is as high as 99% and 90%.

[0021] The activated reaction contains trace HF gas in the reaction byproducts, and the outlet of the oven or other heater is preferably first washed by a 3-10% w / v sodium hydroxide solution and then introduced into a fume hood.

[0022] The domestic sludge incineration ash is subjected to strong acid digestion, and ICP / AES analysis shows that the main element weight percentage composition of the domestic sludge incineration ash is Si 18.45%, P 7.58%, Ca 6.59%, Al 6.12%, Fe 4.11%, K 1.27%, Na 0.54%, Ti 0.54%, Zn 3369ppm, Cu 2032ppm, Ba 961ppm, Cr 654ppm, Mn 406ppm, Ni 315ppm, Sn 188ppm, Pb 161ppm, V 48ppm, Mo 47ppm, Sb 22ppm, Co 22ppm, Ag 18ppm, Li 17ppm, As 5ppm, Cd 0ppm, Hg 0ppm, Se 0ppm.

[0023] The domestic sludge incineration ash is crushed by a ball mill, and more than 99% of the particles are smaller than 125 microns.

[0024] The residue after the solid-liquid separation can be washed with an appropriate amount of clean water for 1-3 times.

[0025] The 1300-1400℃ calcination is carried out in an air atmosphere, and the heating program is as follows: 1-2 hours at 200-300℃ to remove water vapor, 1-2 hours at 650-800℃ to decompose organic matter and convert organic carbon into inorganic carbon and calcium to form calcium carbonate, 1-2 hours at 900-1000℃ to convert calcium carbonate into calcium oxide, and 1-3 hours at 1300-1400℃ to melt all solid species and form very stable compounds in a molten state. The cooling process is natural cooling, and the furnace door can be opened after the furnace temperature decreases to 800℃. Finally, a porous ceramic material is obtained, the pores of which do not conduct to each other, and the material is isolated from water vapor and air, has a low thermal conductivity, and is suitable for use as a high-temperature ceramic refractory and heat insulation material.

[0026] The application has the advantages that compared with the prior art, the application belongs to the technical field of municipal domestic sludge incineration ash treatment process, the domestic sludge incineration ash contains a large amount of heavy metals and is not suitable for direct utilization or landfill, but it contains non-renewable phosphorus resources and other resources (including iron, aluminum, calcium, silicon, magnesium, potassium, copper, zinc, nickel, chromium, lead, etc.) and has utilization value. The literatures all use acid leaching to extract phosphorus and heavy metal precipitating agent to remove heavy metals, and prepare the phosphorus in the form of insoluble or hardly soluble salt to be used as slow-release fertilizer. However, in fact, such hardly soluble or insoluble phosphate has basically no fertility and is false fertilizer. Plants can only absorb ionic phosphate, and hardly soluble or insoluble phosphate can only release extremely small amount of phosphate, and cannot supply the daily growth and reproduction needs of plants. The application discloses that the domestic sludge incineration ash is mainly bound and wrapped by silicate lattice from the essence, so that the leaching efficiency is difficult to improve. The application discards the traditional acid leaching method, directly attacks and destroys the silicon-oxygen lattice of silicate with an activator to make the silicon-oxygen bond break and establish a new silicon-fluorine bond, releases most of the useful resources and heavy metals in the process of breaking the old covalent bond and forming the new covalent bond, and then leaches with a chelating agent, and after treatment, the phosphorus, silicon, iron, copper, zinc, chromium and nickel are fully recovered, and the recovery rates are as high as 99%, 100%, 90%, 99%, 94%, 81% and 83% respectively, far higher than those of the literatures. Basically, the literatures in the field can only recover insoluble or hardly soluble phosphate, and are called slow-release fertilizer, but in fact, the fertility is very poor and is not suitable for urban vertical hydroponic vegetable planting. The application recovers fast-dissolving potassium dihydrogen phosphate, and the fertility is fast and strong and is a phosphorus-potassium dual fertilizer, the concentration of phosphate ions and potassium ions can be strictly controlled, and the application is suitable for various plantings and urban vertical hydroponics. The application recovers silicon dioxide, and the application is very extensive. The copper electrode, metal zinc and nickel-chromium alloy are recovered by electrodeposition, which has not been reported in the literatures. The leaching residue is made into high-temperature ceramic refractory heat insulation material with low thermal conductivity, and the economic value is much higher than that of ordinary foundation building materials, bricks and cement. The unique design of the application enables the main reagents, the activator and the leaching agent, to be recycled, which saves resources and greatly saves costs. There is no sewage and waste gas emission, and the environment is protected while value is created.

[0027] The present application discards the traditional acid leaching method, directly attacks and destroys the silicate silicon-oxygen lattice with an activator to make the silicon-oxygen bond break and establish a new silicon-fluorine bond, forming a fluorosilicate, releasing most of the useful resources and heavy metals in the process of breaking the old covalent bond and forming a new covalent bond, then leaching with a chelating agent, comprehensively recovering phosphorus, silicon, iron, copper, zinc, chromium and nickel through post-processing, and turning the residue into a low thermal conductivity thermal insulation material. The recovered products include potassium dihydrogen phosphate (fast-acting dual-element phosphorus-potassium fertilizer), silicon dioxide (widely used), ferric sulfate (water treatment flocculant), aluminum sulfate (water treatment flocculant), copper electrode (copper electroplating and electric spark machining), metallic zinc (used for galvanizing zinc-based alloys), nickel-chromium alloy (heating wire), and low thermal conductivity high-temperature ceramic thermal insulation material. The main reagents, activator and leaching agent, can be recycled, there is no waste of resources, and the cost is greatly saved. There is no wastewater and waste gas emission, creating value while protecting the environment. BRIEF DESCRIPTION OF DRAWINGS

[0028] The present application for recovering potassium dihydrogen phosphate, silicon dioxide, copper electrode, metallic zinc, nickel-chromium alloy and high-temperature ceramic refractory material from municipal sludge incineration ash and its recovery and manufacturing method will be further described below in conjunction with the drawings and specific embodiments.

[0029] Figure 1 Porous low thermal conductivity high-temperature ceramic thermal insulation material made from residue one plus bauxite and kaolin;

[0030] Figure 2 Dried residue two, sodium fluorosilicate (left), potassium fluorosilicate (right);

[0031] Figure 3 Figure 2 EDS spectrum of dried residue two-potassium fluorosilicate inside;

[0032] Figure 4 Undried residue three (ferric phosphate);

[0033] Figure 5 Undried residue four (calcium phosphate);

[0034] Figure 6 Undried residue five (aluminum hydroxide);

[0035] Figure 7 (left) Filtrate five is electrodeposited on a carbon electrode at a voltage of -2V to -4V for 30 minutes at a stirring speed of 200-300 rpm, and the obtained copper electrode, (middle) FE-SEM microstructure of the copper electrode in the left figure, (right) EDS spectrum of the copper electrode in the left figure;

[0036] Figure 8 Heat and evaporate dry the potassium dihydrogen phosphate solution of filtrate seven, and then purify the obtained solid potassium dihydrogen phosphate;

[0037] Figure 9 The obtained nickel-chromium alloy powder;

[0038] Figure 10 The obtained zinc powder;

[0039] Figure 11 (Left) Original sludge incineration ash, (right) activated sludge incineration ash. DETAILED DESCRIPTION

[0040] As Figures 1 to 3 shown in the figure, the treatment process of the present application for recovering potassium dihydrogen phosphate, silicon dioxide, copper metal electrode, zinc metal, nickel-chromium alloy and high-temperature ceramic refractory material from municipal sludge incineration ash includes:

[0041] A. Activated incineration ash

[0042] Directly attacking and destroying the silicate silicon-oxygen lattice of municipal sludge incineration ash with an activator makes the silicon-oxygen bond break and form new silicon-fluorine bonds to form fluorosilicates, and a large part of useful resources and heavy metals are released in the process of breaking old covalent bonds and forming new covalent bonds. Dry the municipal sludge incineration ash, crush it with a ball mill, and more than 99% of the particles are smaller than 125 microns. Put the municipal sludge incineration ash (such as 1000 grams) in a container (such as a ceramic crucible), add the activator potassium fluoride, sodium fluoride, ammonium hydrogen fluoride or ammonium fluoride according to the weight ratio of activator / incineration ash of 0.1:1-3:1, mix uniformly, and then place it in an oven and heat to 100-180°C for 1-3 hours. This activation reaction, the reaction by-product contains a small amount of HF gas, the oven or other heater exhaust outlet should be washed with 3-10% w / v sodium hydroxide solution first and then absorbed into a fume hood. After the reaction is cooled, the activated incineration ash is obtained.

[0043] B. Chelation leaching

[0044] One of the routes, the fast route (some heat energy will be consumed), the above activated ash (2000-3000g) is transferred to a PTFE reaction container, 2-20 liters of 1-9% w / v EDTA (ethylenediaminetetraacetic acid) extraction solution is added to the activated incineration ash, stirred for 5 minutes, the stirring speed is 200-300 rpm, the pH value is not adjusted and is between 4.3-4.8, the pH value can be adjusted to slightly acidic with sulfuric acid, nitric acid or hydrochloric acid to assist in improving the leaching efficiency of the chelating agent, the pH range is 3.1-4.6, and then stirred for 5 minutes, the stirring speed is 200-300 rpm. Put the PTFE reaction container into a high-pressure reaction kettle without stirring, and react at 120-200°C for 1-3 hours, so that phosphate, fluorosilicate, iron ions, aluminum ions, and most of the heavy metal ions are leached into the solution. After the solution is cooled, the solid-liquid mixture after leaching is subjected to solid-liquid separation to obtain filtrate one and residue one. The residue amount is 50-60% wt.

[0045] Route 2, Energy saving route (longer time), the activated ash (2000-3000g) is transferred to an inert reaction vessel, 2-20 liters of 1-9% w / v EDTA (ethylenediaminetetraacetic acid) extraction solution is added to the activated ash, stirring for 5 minutes, the stirring speed is 200-300 rpm, the pH value is 4.3-4.8 before adjustment, the pH value can be adjusted to slightly acidic with sulfuric acid, nitric acid or hydrochloric acid to assist in improving the leaching efficiency of the chelating agent, the pH range is 3.1-4.6, and then stirring for 18-24 hours, the stirring speed is 800-1000 rpm. The phosphate, fluorosilicate, iron ion, aluminum ion, and most of the heavy metal ions are leached into the solution. The solid-liquid separation is performed on the solid-liquid mixture after the leaching is completed to obtain a filtrate I and a residue I. The residue amount is 50-60% wt. The residue after solid-liquid separation can be washed with an appropriate amount of clean water for 1-3 times.

[0046] C. Residue I post-treatment

[0047] Take the dry residue I after extraction, according to EDS analysis, the main components are calcium aluminate and quartz. Add bauxite and kaolin, mix evenly according to the weight ratio of residue I:bauxite:kaolin 1:0.5-1.5:0.5-1.5, and calcine in a superhigh temperature muffle furnace at 1300-1400°C for 1-3 hours to obtain a high-temperature ceramic refractory thermal insulation material with low thermal conductivity. Figure 1 According to EN12457-1, the leaching test is performed, and all 18 metals and heavy ions meet the strict standards (Singapore NEA Reference Value 2018) (Table 1). The calcination temperature is 1300-1400°C, the atmosphere is air, the heating program is to stay at 200-300°C for 1-2 hours to remove water vapor, stay at 650-800°C for 1-2 hours to decompose organic matter and convert organic carbon to inorganic carbon and calcium to form calcium carbonate, stay at 900-1000°C for 1-2 hours to convert calcium carbonate to calcium oxide, and stay at 1300-1400°C for 1-3 hours to melt all solid species, and in the molten state, the species react with each other to form a very stable compound. The cooling process is natural cooling, and the furnace door can be opened after the furnace temperature decreases to 800°C. Finally, a porous ceramic material is obtained, the pores between the holes are not conductive to each other, water vapor and air are isolated, the thermal conductivity is low, and it is suitable for high-temperature ceramic refractory thermal insulation materials.

[0048] Table 1 Leaching test according to EN12457-1, the amount of harmful species leached and the Singapore NEA Reference Value standard (29Jun 2023 version) comparison

[0049]

[0050]

[0051] D. Post-treatment of filtrate

[0052] Add 90-100 g of potassium chloride or 70-80 g of sodium chloride to 1.5 L of filtrate one, stir for 1 minute at 100-200 rpm, and let it age for 10 minutes to form potassium fluorosilicate or sodium fluorosilicate precipitate. Separate the solid and liquid to obtain filtrate two and residue two (fluorosilicate). The residue after solid-liquid separation can be washed 1-3 times with an appropriate amount of clean water. Figure 2 The dried residues are shown: sodium fluorosilicate (left) and potassium fluorosilicate (right). Figure 3 Showing Figure 2 The EDS spectrum of the dried residue potassium difluorosilicate shows that only potassium, silicon and fluorine are present, indicating very high purity. The carbon peaks shown are not impurities but carbon from the carbon tape used for EDS spectroscopy and do not belong to the sample peaks.

[0053] Sodium hydroxide was added to filtrate two to adjust the pH to 4-5, and the mixture was stirred for 1 minute at a stirring speed of 100-200 rpm. After aging for 10 minutes, ferric phosphate precipitate was formed. Due to the influence of the chelating extractant, the iron recovery rate of the first extraction was only 50-60%. Solid-liquid separation yielded filtrate three and residue three (ferric phosphate). Figure 4 ).

[0054] Add 27-54 g of calcium chloride and calcium hydroxide to filtrate three to bring the pH to 6, then add more calcium hydroxide to bring the pH to 6 again. Stir for 1 minute at 100-200 rpm and let it age for 10 minutes, producing a white precipitate of calcium phosphate. Due to the influence of the chelating extractant, the phosphate recovery rate of the first extraction is only 50-60%. Solid-liquid separation yields filtrate four and residue four (calcium phosphate). Figure 5 ).

[0055] Add NaOH to filtrate four until the pH reaches 7-9, stir for 1 minute at 100-200 rpm, and let it age for 10 minutes to produce aluminum hydroxide precipitate (not aluminum phosphate). Solid-liquid separation yields filtrate five and residue five (aluminum hydroxide). Figure 6 ).

[0056] Filtrate 5 was electrodeposited on a copper or carbon electrode at a voltage of -2V to -4V for 30 minutes with a stirring speed of 200-300rpm to obtain a copper electrode. Figure 7 It is widely used in copper electroplating and electrical discharge machining. Figure 7 The left figure shows the copper electrode obtained by electrodepositing filtrate 5 on a carbon electrode for 30 minutes at a voltage of -2V to -4V and a stirring speed of 200-300rpm. Figure 7 The middle image shows the FE-SEM microstructure of the copper electrode in the left image. Figure 7The right figure shows the EDS spectrum of the copper electrode in the left figure. The spectrum shows only copper and platinum metals, with the platinum metal being a thin platinum layer deposited on its surface for SEM and EDS spectroscopy. The copper recovery rate reached 99%. Solid-liquid separation of the electrolyte solution yielded filtrate and residue consisting of a mixed precipitate of nickel hydroxide, zinc hydroxide, and chromium hydroxide.

[0057] Add 50-80 ml of 1-2 M potassium hydroxide solution to 10 g of dried residue 3 (ferric phosphate), stir for 30 minutes at a stirring speed of 300-500 rpm, to form ferric hydroxide precipitate and potassium dihydrogen phosphate solution. Separate the electrolyte to obtain filtrate 7 and residue 7 (ferric hydroxide). Heat and evaporate the potassium dihydrogen phosphate solution of filtrate 7 to dry it, then purify to obtain solid potassium dihydrogen phosphate. Figure 8 It can be used as a quick-dissolving binary fertilizer for agriculture, forestry, horticulture, and urban vertical hydroponics.

[0058] Add 50-80 ml of 1-2M potassium hydroxide solution to 10 g of dried residue four (calcium phosphate), stir for 30 minutes at 300-500 rpm, to generate calcium hydroxide precipitate and potassium dihydrogen phosphate solution. Separate the electrolyte to obtain filtrate eight and residue eight (calcium hydroxide). Filtrate eight contains a small amount of calcium ions, which can be removed by adding a little oxalic acid precipitation. Separate the electrolyte to obtain filtrate nine and residue nine (calcium oxalate). Residue eight (calcium hydroxide), after drying, becomes product calcium hydroxide, which can be used to treat filtrate three. Heat and evaporate the potassium dihydrogen phosphate solution from filtrate seven and filtrate nine to dry, then purify to obtain solid potassium dihydrogen phosphate, which can be used in agriculture, forestry, horticulture, and as a quick-dissolving binary phosphorus and potassium fertilizer for urban vertical hydroponics.

[0059] Add 2-2.5 grams of concentrated sulfuric acid to 1 gram of dried ferric hydroxide residue precipitate, stir at 100-200 rpm for 10 minutes, and then dry and purify to obtain solid ferric sulfate, which can be used as a flocculant for water treatment. Add 2-3 grams of concentrated sulfuric acid to 1 gram of dried aluminum hydroxide residue precipitate, stir at 100-200 rpm for 10 minutes, and then dry and purify to obtain solid aluminum sulfate, which can also be used as a flocculant for water treatment.

[0060] Add 20-50 ml of 0.2-1 M sodium hydroxide solution to 1 gram of a dried precipitate of residual nickel hydroxide, zinc hydroxide, and chromium hydroxide. Stir for 10 minutes at 300-500 rpm to dissolve the zinc hydroxide. Separate the solid and liquid phases to obtain a filtrate and a mixture of residual nickel hydroxide and chromium hydroxide, and dry them. Heat 1 gram of the residual nickel hydroxide and chromium hydroxide mixture to 600-800℃ in air to first convert it into a mixture of nickel oxide and chromium oxide. Add 0.2-0.5 grams of carbon powder, mix thoroughly, and then heat to 600-800℃ in a nitrogen atmosphere to reduce it to a nickel-chromium alloy. High-purity nickel-chromium alloy is obtained. Figure 9Nickel and chromium are widely used as heating wire materials. The recovery rates of nickel and chromium are as high as 83% and 81%, respectively.

[0061] Add sulfuric acid to the dissolved zinc hydroxide solution in the aforementioned filtrate 10 to adjust the pH to 6-8, stir for 1 minute at a stirring speed of 100-200 rpm, and let it age for 10 minutes to form zinc hydroxide precipitate. Separate the solid and liquid components to obtain filtrate 11 and residue 11 (zinc hydroxide). Dry 1 gram of residue 11 into zinc hydroxide, heat to 600-800℃ in air to first convert it into zinc oxide, add 0.3-0.5 grams of carbon powder, mix well, and then heat to 600-800℃ in a nitrogen atmosphere to reduce it to metallic zinc (…). Figure 10 The zinc recovery rate is as high as 94%.

[0062] E. Activator regeneration cycle

[0063] Add 3.0-4.0 ml of 25% wt. ammonia to the dried solid potassium fluorosilicate or sodium fluorosilicate (e.g., 5 g), stir for 2-5 hours at 300-500 rpm, and a white precipitate of silica will form. Separate the solid and liquid phases to obtain filtrate XII and residue XII (silica). Dry residue XII to obtain the product silica. Evaporate filtrate XII to precipitate sodium fluoride or potassium fluoride, and separate the solid and liquid phases to obtain filtrate XIII and residue XIII (sodium fluoride or potassium fluoride). Dry residue XIII to obtain the product sodium fluoride or potassium fluoride, which is an activator and can be recycled. Evaporate filtrate XIII to dryness to obtain the product ammonium fluoride. The product ammonium fluoride is also an activator and can be recycled.

[0064] F. Chelating extract regeneration cycle

[0065] Filtrate 6 contains extractant, most of which is in a free, unchelated state. A small portion of the extractant has chelated iron, but this does not affect recycling. Due to the influence of the chelated extractant, the recovery rate of phosphoric acid and iron in the first extraction is only 50-60%. Adding a second batch of activated incinerator ash to filtrate 6 and operating according to step BF results in recovery rates of 99% and 90% for phosphoric acid and iron in the second and subsequent extractions, respectively.

[0066] The following are specific implementation details:

[0067] Example 1

[0068] The ash from the incineration of municipal solid waste sludge, after strong acid digestion and ICP / AES analysis, showed the following main elemental composition by weight percentage: Si 18.45%, P 7.58%, Ca 6.59%, Al 6.12%, Fe 4.11%, K 1.27%, Na 0.54%, Ti 0.54%, Zn 3369ppm, Cu 2032ppm, Ba 961ppm, Cr 654ppm, Mn 406ppm, Ni 315ppm, Sn 188ppm, Pb 161ppm, V 48ppm, Mo 47ppm, Sb 22ppm, Co 22ppm, Ag 18ppm, Li 17ppm, As 5ppm, Cd 0ppm, Hg 0ppm, Se 0ppm.

[0069] Example 2

[0070] Burn 10 grams of domestic sewage sludge to ash ( Figure 11 Add 10 grams of sodium fluoride to the left, mix well, and place in an oven at 130°C for 3 hours. This yields activated ash. Figure 11 right).

[0071] Example 3

[0072] Add 100 ml of 3% wt. EDTA to the activated ash from Example 2, adjust the pH to 3.8, stir for 5 minutes, place in a high-pressure reactor, and react at 190℃ for 1 hour. Separate the solid and liquid phases to obtain a solution and filter residue. Let the solution stand at room temperature (20-30℃) for 3 days; a white precipitate (EDTA) will form. Separate the solid and liquid phases to obtain the filtrate and EDTA. EDTA can be recycled. EDTA will still be present in the filtrate.

[0073] Example 4

[0074] 100 ml of the filtrate from Example 3 was mixed with 23.5 g of sodium chloride and stirred to obtain sodium fluorosilicate. ICP / AES analysis of the solutions before and after precipitation revealed a silicon content of 94.8% wt. Solid-liquid separation was performed. The pH of the filtrate was adjusted to 4 to obtain ferric phosphate precipitate. Solid-liquid separation was then performed. 2 g of calcium chloride was added to the filtrate, and the pH was adjusted to 5 to obtain calcium phosphate precipitate. Solid-liquid separation was performed again, and the pH was adjusted to 8 to obtain aluminum hydroxide precipitate. Solid-liquid separation was then performed.

[0075] Example 5

[0076] The final filtrate from Example 4, pH 8, was electrodeposited using a carbon electrode at -3V for 20 minutes to obtain a copper-plated carbon electrode and a mixture of zinc hydroxide, nickel hydroxide, and chromium hydroxide residue. 5 ml of 0.5M sodium hydroxide solution was added to the residue, and the mixture was stirred for 10 minutes to dissolve the zinc hydroxide. Solid-liquid separation yielded the filtrate and the nickel hydroxide and chromium hydroxide mixture residue. The residue was dried and heated to 800℃ for 60 minutes in air to first convert it into a mixture of nickel oxide and chromium oxide. 0.5 g of carbon powder was added, and the mixture was thoroughly mixed. Then, the mixture was heated to 800℃ for 40 minutes in a nitrogen atmosphere to reduce it to a nickel-chromium alloy.

[0077] Add sulfuric acid to the above zinc hydroxide solution to adjust the pH to 7, stir for 1 minute at a stirring speed of 100-200 rpm, and let it age for 10 minutes to form zinc hydroxide precipitate. Separate the solid and liquid to obtain filtrate and residue (zinc hydroxide), dry, and heat to 800℃ for 60 minutes to first convert it to zinc oxide in an air atmosphere. Add 0.3 g of carbon powder, mix well, and then heat to 800℃ for 40 minutes in a nitrogen atmosphere to reduce it to metallic zinc.

[0078] Example 6

[0079] In Example 4, ferric phosphate was added to 18 ml of 2.0 N KOH, stirred for 60 minutes, filtered, and the filtrate and residue were obtained. The residue was ferric hydroxide, which was added to 5.4 g of sulfuric acid, stirred evenly, and dried to obtain ferric sulfate. The pH of the filtrate was adjusted to 5.8 with a small amount of phosphoric acid, and evaporated to dryness to obtain potassium dihydrogen phosphate.

[0080] Example 7

[0081] The filter residue from Example 3 was washed twice with 10 ml of water each time, and dried to obtain 5.8 g. EDS analysis showed its main components were calcium aluminate and quartz. 3 g of bauxite and 3 g of kaolin were added, mixed thoroughly, and placed in an ultra-high temperature muffle furnace under an air atmosphere. Heating was performed at 250℃, 800℃, and 1000℃ for 1 hour each, and at 1350℃ for 3 hours. Natural cooling was allowed, and the furnace door was opened after the temperature dropped to 800℃. The final product was a porous ceramic material with non-conductive pores, effectively isolating water vapor and air. Its low thermal conductivity makes it suitable for use as a high-temperature ceramic refractory insulation material.

[0082] Example 8

[0083] The sodium fluorosilicate obtained in Example 4, after drying, was 1 gram, mixed with 1.7 ml of ammonia and 12 ml of water, and stirred for 180 minutes. The mixture was then centrifuged to separate the solid and liquid phases, yielding a supernatant and a precipitate. The precipitate was silica. The supernatant contained NaF and NH4F; after evaporation to dryness, a solid mixture of NaF and NH4F was obtained, which can be recycled as an activator.

[0084] Example 9

[0085] 1.0 g of sludge incineration ash with a particle size of less than 125 micrometers after ball milling and 2.5 g of activator were mixed evenly, heated to 160℃ and maintained for 2 hours, cooled, and then 15.0 ml of deionized water was added. The mixture was stirred at room temperature for 60 minutes at a stirring speed of 450 rpm, centrifuged, and the supernatant was analyzed by ICP-AES. The leaching efficiency of deionized water is shown in Table 2. It can be seen that even after activation, the leaching efficiency of deionized water for heavy metals (zinc, copper, nickel, chromium) in sludge incineration ash is very low.

[0086] Table 2. Extraction efficiency of deionized water within 60 minutes after activation of sludge incineration ash.

[0087] Element P Zn Cu Ni Cr Leaching efficiency 40.01％ 2.50％ 2.92％ 9.01％ 7.32％

[0088] Example 10

[0089] 15.0 ml of 1.2% wt. EDTA was added to 1.0 g of ball-milled sludge incineration ash with a particle size of less than 125 micrometers. The mixture was stirred at room temperature for 10 minutes at a stirring speed of 450 rpm and ultrasonicated for 20 minutes. Then, it was placed in a high-pressure reactor and heated to 150°C for 2 hours. After centrifugation, the supernatant was analyzed by ICP-AES. The leaching efficiency of 15.0 ml of 1.2% wt. EDTA is shown in Table 3. It can be seen that EDTA has a very low leaching efficiency for heavy metals (zinc, iron, lead) in unactivated sludge incineration ash.

[0090] Table 3. Extraction yield of 1.2% wt. EDTA in 15.0 ml of unactivated sludge incineration ash

[0091] Element Zn Fe Pb Leaching efficiency 6.57％ 6.20％ 17.47％

[0092] Example 11

[0093] 1.0 g of ball-milled sludge incineration ash with a particle size less than 125 micrometers was mixed with 1.5 g of activator and heated to 160℃ for 2 hours. After cooling, 15.0 ml of 0.6% wt. EDTA was added and stirred at room temperature for 1 hour at a stirring speed of 450 rpm. After centrifugation, the supernatant was analyzed by ICP-AES. The extraction efficiency is shown in Table 4. The extraction efficiency is much higher than that of simple activation without chelation extraction (Table 2) and simple chelation extraction without activation (Table 3), indicating that only by combining activation and chelation extraction can a high extraction rate be achieved.

[0094] Table 4. Extraction efficiency of low-concentration EDTA on activated sludge incineration ash at room temperature for 1 hour.

[0095] Element P Zn Cu Ni Cr Leaching efficiency 56.28％ 36.90％ 60.77％ 28.72％ 10.72％

[0096] Example 12

[0097] 1.0 g of ball-milled sludge incineration ash with a particle size less than 125 micrometers was mixed with 2.5 g of activator and heated to 160℃ for 2 hours. After cooling, 15.0 ml of 1.2% wt. EDTA was added to adjust the pH to 3.2, and the mixture was stirred at room temperature for 10 minutes at a stirring speed of 450 rpm. The mixture was then sonicated for 20 minutes. The mixture was then placed in a high-pressure reactor and heated to 150℃ for 2 hours. After centrifugation, the supernatant was analyzed by ICP-AES. The extraction efficiency is shown in Table 5. The extraction efficiency was much higher than that of low-concentration, room-temperature, short-time extraction (Table 4), indicating that the chelating agent concentration, extraction temperature, and extraction time all affect the extraction rate.

[0098] Table 5. Extraction efficiency of medium concentration EDTA on activated sludge incineration ash at 150℃ for 2 hours

[0099] Element P Zn Cu Ni Cr Si Ti Sn Leaching efficiency 92.84％ 100％ 100％ 100％ 36.26％ 100％ 28.33％ 70.26％ Element Co Sb Mo Ba Fe Pb Mn V Leaching efficiency 75.24％ 41.04％ 93.33％ 0.16％ 58.46％ 36.24％ 43.25％ 91.33％

[0100] Example 13

[0101] 2.5 g of activator, 2 ml of deionized water, and 1.0 g of ball-milled sludge incineration ash with a particle size less than 125 microns were added and mixed for 20 minutes until homogeneous. The mixture was then ultrasonicated for 10 minutes and evaporated to dryness at 95°C. The mixture was then heated to 160°C for 2 hours. After cooling, 15.0 ml of 6% wt. EDTA was added to adjust the pH to 3.2. The mixture was stirred at room temperature for 10 minutes at 450 rpm. Ultrasonication was then performed for 20 minutes. The mixture was then placed in a high-pressure reactor and heated to 160°C for 2 hours. After centrifugation, the residue was added to 50 ml of a solution (containing 1% wt. sodium bisulfite, 5.5% wt. ammonium chloride, 0.6% wt. EDTA, and 5 mM sulfuric acid) and washed at 100°C for 1 hour. Solid-liquid separation was performed. The residue was washed four times with 50 ml of deionized water. After solid-liquid separation, the residue was thoroughly dried at 80°C. The percolation safety test was conducted according to BS EN12457-1, and the results, calculated by solid content, are shown in Table 6. It can be seen that the percolation rates of all heavy metals are very low. The percolation rates of the 13 heavy metals Ni, V, As, Cd, Co, Cu, Hg, Mo, Ag, Se, Sn, Sb, and Pb are all 0; Zn is 0.30 ppm; total Cr is 0.32 ppm; Mn is 0.16 ppm, all less than 0.5 ppm; Ba is 3.4 ppm; and Na is 220.6 ppm, which is also very low. This indicates that this slag can be used as a raw material for resource recovery.

[0102] Table 6. Results of the leachate safety test of sludge incineration ash after activation, chelation extraction, and washing, according to BS EN12457-1 (leachate volume is expressed as solid content).

[0103] Element Zn Ni Cr V Mn As Dry leach mass (mg / kg) 0.30 0.00 0.32 0.00 0.16 0.00 Element Ba Cd Co Cu Hg Mo Dry leach mass (mg / kg) 3.40 0.00 0.00 0.00 0.00 0.00 Element Na Ag Se Sn Sb Pb Dry leach mass (mg / kg) 220.6 0.00 0.00 0.00 0.00 0.00

[0104] The present invention has been described in an illustrative rather than restrictive manner according to embodiments thereof. However, it should be understood that the scope of protection of the present invention is not limited thereto. Without departing from the relevant scope of protection defined by the claims, those skilled in the art can make changes and / or modifications. Any modifications, equivalent substitutions, etc., based on this should be covered within the scope of protection of the present invention.

Claims

1. A method for recovering potassium dihydrogen phosphate, silicon dioxide, metallic copper electrodes, metallic zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials from municipal sewage sludge incineration ash, characterized in that: This process involves directly attacking and destroying the silicon-oxygen lattice of silicates with an activating agent, causing the silicon-oxygen bonds to break and new silicon-fluorine bonds to form fluorosilicates. During the process of breaking old covalent bonds and forming new covalent bonds, most of the useful resources and heavy metals are released. Then, chelating agents are used for extraction, and post-processing is carried out to fully recover phosphorus, silicon, iron, copper, zinc, chromium, and nickel. The residue is then used to make low thermal conductivity insulation materials. The recovered products include potassium dihydrogen phosphate, silicon dioxide, metallic copper electrodes, metallic zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials. The processing flow is as follows: A. Activated incineration ash The activator directly attacks and destroys the silicate silicon-oxygen lattice of municipal sewage sludge incineration ash, causing the silicon-oxygen bonds to break and new silicon-fluorine bonds to be established, forming fluorosilicates. During the process of breaking the old covalent bonds and forming new covalent bonds, most of the useful resources and heavy metals are released. 1000 grams of municipal sewage sludge incineration ash is placed in a container, and potassium fluoride, sodium fluoride, ammonium bifluoride or ammonium fluoride, or other activators are added at a weight ratio of 0.1:1 to 3:

1. After mixing evenly, the mixture is placed in an oven and heated to 100-180℃ for 1-3 hours. After the reactants are cooled, activated incineration ash is obtained. B. Chelation extraction Rapid route: Transfer the activated ash to a PTFE reaction vessel, add 2-20 liters of 1-9% w / v EDTA (ethylenediaminetetraacetic acid) extract to the activated incineration ash, stir for 5 minutes at a stirring speed of 200-300 rpm, adjust the pH value to slightly acidic using sulfuric acid, nitric acid, or hydrochloric acid (pH range 3.1-4.6), stir for another 5 minutes at a stirring speed of 200-300 rpm, place the PTFE reaction vessel into a high-pressure reactor, and react at 120-200℃ for 1-3 hours without stirring, so that phosphate, fluorosilicate, iron, aluminum, and most heavy metal ions are leached into the solution. After the solution cools, perform solid-liquid separation on the solid-liquid mixture after leaching to obtain filtrate one and residue one, with a residue amount of 50-60% wt. Energy-saving route: Transfer the activated ash to an inert reaction vessel, add 2-20 liters of 1-9% w / v EDTA (ethylenediaminetetraacetic acid) extract to the activated incineration ash, stir for 5 minutes at a stirring speed of 200-300 rpm, and adjust the pH value to slightly acidic (pH range 3.1-4.6) using sulfuric acid, nitric acid, or hydrochloric acid, and then stir for 18-24 hours at a stirring speed of 800-1000 rpm to leach phosphate, fluorosilicate, iron, aluminum, and most heavy metal ions into the solution. Separate the solid-liquid mixture after leaching to obtain filtrate 1 and residue 1, with a residue amount of 50-60% wt. C. Post-treatment of residue The dried residue 1 after extraction was analyzed by EDS and found to be mainly composed of calcium aluminate and quartz. Bauxite and kaolin were added and mixed evenly at a weight ratio of residue 1:bauxite:kaolin of 1:0.5-1.5:0.5-1.

5. The mixture was then calcined in an ultra-high temperature muffle furnace at 1300-1400℃ for 1-3 hours to obtain high-temperature ceramic refractory material. D. Post-treatment of filtrate Add 90-100 g of potassium chloride or 70-80 g of sodium chloride to 1.5 L of filtrate one, stir for 1 minute at 100-200 rpm, and let it age for 10 minutes to form potassium fluorosilicate or sodium fluorosilicate precipitate. Separate the solid and liquid to obtain filtrate two and residue two. Add sodium hydroxide to filtrate two to adjust the pH to 4-5, stir for 1 minute at 100-200 rpm, and let it age for 10 minutes to form ferric phosphate precipitate. Due to the influence of the chelating extractant, the iron recovery rate of the first leaching is 50-60%. Separate the solid and liquid to obtain filtrate three and residue three. Add 27-54 g of calcium chloride and calcium hydroxide to filtrate three to adjust the pH to 6, and then add calcium hydroxide to adjust the pH to 6. At pH 6, stir for 1 minute at 100-200 rpm, then age for 10 minutes to produce a white precipitate of calcium phosphate. Due to the influence of the chelating extractant, the phosphate recovery rate of the first extraction is 50-60%. Solid-liquid separation yields filtrate four and residue four. Filtrate four is then treated with NaOH to pH 7-9, stirred for 1 minute at 100-200 rpm, and aged for 10 minutes to produce aluminum hydroxide precipitate. Solid-liquid separation yields filtrate five and residue five. Filtrate five is electrodeposited on a copper or carbon electrode at -2V to -4V for 30 minutes at 200-300 rpm to obtain a copper electrode, which is widely used in copper electroplating and electrical discharge machining. The copper recovery rate is 99%. Solid-liquid separation of the electrolyte solution yields filtrate six and residue six, a mixed precipitate of nickel hydroxide, zinc hydroxide, and chromium hydroxide. Add 50-80 ml of 1-2M potassium hydroxide solution to 10 g of dried residue three, stir for 30 minutes at 300-500 rpm, generating ferric hydroxide precipitate and potassium dihydrogen phosphate solution. Solid-liquid separation of the electrolyte yields filtrate seven and residue seven. The potassium dihydrogen phosphate solution in filtrate seven is heated and evaporated to dryness, then purified to obtain solid potassium dihydrogen phosphate, which can be used in agriculture, forestry, horticulture, and as a fast-dissolving binary phosphorus and potassium fertilizer for urban vertical hydroponics. Add 50-80 ml of 1-2M potassium hydroxide solution to 10 g of dried residue four... M potassium hydroxide solution, stirred for 30 minutes at 300-500 rpm, produces calcium hydroxide precipitate and potassium dihydrogen phosphate solution. Solid-liquid separation electrolyte yields filtrate 8 and residue 8. Filtrate 8 contains a small amount of calcium ions, which can be removed by adding a little oxalic acid precipitation. Solid-liquid separation electrolyte yields filtrate 9 and residue 9. Residue 8 calcium hydroxide, after drying, becomes product calcium hydroxide, which can be used to treat filtrate 3. Filtrates 7 and 9 potassium dihydrogen phosphate solution are heated and evaporated to dryness, then purified to obtain solid potassium dihydrogen phosphate, which can be used in agriculture, forestry, horticulture, and as a quick-dissolving binary fertilizer for urban vertical hydroponics. Add 2-2...Solid ferric sulfate is prepared by stirring 5 grams of concentrated sulfuric acid at 100-200 rpm for 10 minutes, followed by drying and purification. It can be used as a flocculant in water treatment. Solid aluminum sulfate is also prepared by adding 2-3 grams of concentrated sulfuric acid to 1 gram of dried aluminum hydroxide residue precipitate at 100-200 rpm for 10 minutes, followed by drying and purification. It can also be used as a flocculant in water treatment. Finally, solid aluminum sulfate is prepared by adding 20-50 ml of 0.2-1M sodium hydroxide solution to 1 gram of a mixed dried precipitate of nickel hydroxide, zinc hydroxide, and chromium hydroxide residue at 300-500 rpm for 10 minutes. Dissolve zinc hydroxide at rpm, separate the solid and liquid phases to obtain a filtrate and a residue mixture of nickel hydroxide and chromium hydroxide. Dry the residue mixture of nickel hydroxide and chromium hydroxide and heat it to 600-800℃ in air to first convert it into a mixture of nickel oxide and chromium oxide. Add 0.2-0.5 grams of carbon powder, mix well, and then heat it to 600-800℃ in a nitrogen atmosphere to reduce it to a nickel-chromium alloy, obtaining a high-purity nickel-chromium alloy, which is widely used as a heating wire material. The recovery rates of nickel and chromium are 83% and 81%, respectively. The filtrate (10) was dissolved in zinc hydroxide solution. Sulfuric acid was added to adjust the pH to 6-8. The mixture was stirred for 1 minute at 100-200 rpm and aged for 10 minutes to form zinc hydroxide precipitate. Solid-liquid separation was performed to obtain filtrate (11) and residue (11). 1 gram of residue (11) was dried to obtain zinc hydroxide and heated to 600-800℃ in air to convert it into zinc oxide. 0.3-0.5 grams of carbon powder were added and mixed thoroughly. Then, the mixture was heated to 600-800℃ in a nitrogen atmosphere to reduce it to metallic zinc. The zinc recovery rate was 94%. E. Activator Regeneration Cycle Add 3.0-4.0 ml of 25% wt. ammonia to the dried residue (solid potassium fluorosilicate or sodium fluorosilicate), stir for 2-5 hours at a stirring speed of 300-500 rpm, and a white precipitate of silica will be formed. Separate the solid and liquid to obtain filtrate (II) and residue (II). Dry residue (II) to obtain product silica. Evaporate filtrate (II) to precipitate sodium fluoride or potassium fluoride. Separate the solid and liquid to obtain filtrate (III) and residue (III). Dry residue (III) to obtain product sodium fluoride or potassium fluoride, which is an activator and can be recycled. Evaporate filtrate (III) to dryness to obtain product ammonium fluoride, which is also an activator and can be recycled. F. Chelating extractant regeneration cycle The filtrate contains an extractant, most of which is in a free, unchelated state. A small portion of the extractant has chelated iron, but this does not affect recycling. Due to the influence of the chelated extractant, the first extraction of phosphoric acid and iron is carried out. The second batch of activated incineration ash is added to the filtrate and the BF operation is followed. The recovery rates of phosphoric acid and iron in the second and subsequent extractions are 99% and 90%, respectively.

2. The method for recovering potassium dihydrogen phosphate, silicon dioxide, copper electrodes, zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials from municipal sludge incineration ash according to claim 1, characterized in that: The activation reaction produces byproducts containing trace amounts of HF gas. The gas outlet of the oven or other heater should first be washed with a 3-10% w / v sodium hydroxide solution to absorb the HF gas before it is introduced into the fume hood.

3. The method for recovering potassium dihydrogen phosphate, silicon dioxide, metallic copper electrodes, metallic zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials from municipal sludge incineration ash according to claim 1, characterized in that: The incineration ash of the municipal sewage sludge, after strong acid digestion and ICP / AES analysis, showed the following main element weight percentage composition: Si 18.45%, P 7.58%, Ca 6.59%, Al 6.12%, Fe 4.11%, K 1.27%, Na 0.54%, Ti 0.54%, Zn 3369 ppm, Cu 2032 ppm, Ba 961 ppm, Cr 654 ppm, Mn 406 ppm, Ni 315 ppm, Sn 188 ppm, Pb 161 ppm, V 48 ppm, Mo 47 ppm, Sb 22 ppm, Co 22 ppm, Ag 18 ppm, Li 17 ppm, As 5 ppm, Cd 0 ppm, Hg 0 ppm, Se 0 ppm.

4. The method for recovering potassium dihydrogen phosphate, silicon dioxide, metallic copper electrodes, metallic zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials from municipal sludge incineration ash according to claim 1, characterized in that: The incineration ash of the municipal sludge is pulverized by a ball mill, and more than 99% of the particles are smaller than 125 micrometers.

5. The method for recovering potassium dihydrogen phosphate, silicon dioxide, metallic copper electrodes, metallic zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials from municipal sludge incineration ash according to claim 1, characterized in that: The residue after solid-liquid separation can be washed 1-3 times with an appropriate amount of clean water.

6. The method for recovering potassium dihydrogen phosphate, silicon dioxide, metallic copper electrodes, metallic zinc, nickel-chromium alloys, and high-temperature ceramic refractory materials from municipal sludge incineration ash according to claim 1, characterized in that: The aforementioned calcination at 1300-1400℃ is performed in an air atmosphere. The heating process involves holding the furnace at 200-300℃ for 1-2 hours to remove moisture, holding it at 650-800℃ for 1-2 hours to decompose organic matter and convert organic carbon into inorganic carbon, which combines with calcium to form calcium carbonate. The furnace is then held at 900-1000℃ for 1-2 hours to convert calcium carbonate into calcium oxide. Finally, the furnace is held at 1300-1400℃ for 1-3 hours to melt all solid species. In the molten state, the various species react with each other to form a very stable compound. The cooling process is natural cooling. After the furnace temperature drops to 800℃, the furnace door can be opened. Finally, a porous ceramic material is obtained, in which the pores are not interconnected, isolating moisture and air. It has a low thermal conductivity and is suitable for use as a high-temperature ceramic refractory insulation material.

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