A method for disposal of waste incineration fly ash

Abstract

The present application belongs to the field of hazardous waste resource, and discloses a disposal method of waste incineration fly ash. The method comprises the following steps: mixing waste incineration fly ash, copper slag and carbon-containing reducing agent into smelting base material, roasting, and separating the melt generated by roasting into copper-rich liquid phase and slag liquid phase by using density difference static separation; then cooling the copper-rich liquid phase to obtain copper-rich product, and cooling the slag liquid phase to obtain vitrification product. By introducing copper slag as a synergistic fluxing agent in the smelting base material, the consumption of exogenous mineral additives is not needed, and the copper recovery rate and the recovery quality of the vitrification product are improved, thereby realizing the reduction of the disposal cost of waste incineration fly ash, the deep recovery of secondary resources, and remarkable environmental protection and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of hazardous waste resource utilization technology, and more specifically, relates to a method for disposing of fly ash from waste incineration. Background Technology

[0002] Fly ash from waste incineration is a product collected by the flue gas purification system during the waste incineration process, and its production increases year by year with the amount of waste incinerated. It contains environmentally hazardous substances such as dioxins, heavy metals, and chloride salts. If it is not treated in a timely and proper manner, it will cause serious harm to environmental safety and human health.

[0003] Currently, the main method for treating fly ash is water washing and desalination followed by chelation solidification and landfilling. However, this method consumes a large amount of land resources and cannot simultaneously decompose dioxins and stabilize heavy metals. High-temperature melting is considered a promising treatment method for fly ash because it can effectively degrade dioxins and stabilize heavy metals. This method usually involves adding silicon-based additives to construct a vitrified framework to solidify heavy metals. Chinese patent CN118791227A discloses a method for vitrifying fly ash, in which fly ash is mixed with silicon- and aluminum-containing raw materials and then subjected to high-temperature melting to obtain a vitrified body. Chinese patent CN119857716B describes a method for water washing and desalination of fly ash, followed by high-temperature sintering to allow the chlorine from the decomposition of dioxins in the fly ash to react with heavy metals to form gaseous heavy metal chlorides. Simultaneously, magnesium or calcium salts added during the high-temperature sintering process react with the ash in the fly ash to form magnesium silicate and calcium silicate, thereby enhancing the lattice solidification ability of the sintered body. Chinese patent CN118237385A describes a method for decomposing dioxins and solidifying heavy metals in fly ash by washing it with water, mixing it with coke, flux, and thickening agents, and then smelting it. Chinese patent CN111250510B discloses a segmented fly ash melting treatment device and method, with a melting temperature exceeding 1400℃. While these methods can transform fly ash into a safe and stable glassy substance or sintered product, the high energy consumption and reagent costs, coupled with low economic added value, make industrial-scale application difficult. Chinese patent CN121156010B describes mixing fly ash with NaCl or KCl solution, using a high concentration of NaCl... + K + Competitive ion exchange with heavy metal ions can efficiently leach heavy metals and soluble salts from fly ash, but the heavy metals enriched in the leachate require extremely precise recovery processes. Improper handling can easily cause secondary pollution of water bodies.

[0004] Therefore, developing a new pyrometallurgical disposal technology for fly ash that does not require the addition of expensive fluxes and can efficiently recover high-value metals has become a key issue that urgently needs to be addressed in the field of hazardous waste resource utilization. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method for the disposal of waste incineration fly ash, which aims to solve the technical problem that it is difficult to balance the disposal cost and product benefits of existing waste incineration fly ash.

[0006] To achieve the above objectives, the present invention provides a method for disposing of waste incineration fly ash, comprising: mixing waste incineration fly ash, copper slag and carbon-containing reducing agent as a smelting base material, and calcining the mixture; wherein the melt produced by calcination is separated into a copper-rich liquid phase and a slag-liquid phase by static settling based on density difference; and then cooling the copper-rich liquid phase to obtain a copper-rich product and cooling the slag-liquid phase to obtain a vitrified product.

[0007] Preferably, the binary basicity of the smelting base material is 0.5-1.

[0008] Preferably, the waste incineration fly ash contains 20-40 wt% calcium, 1-10 wt% silicon, 5-20 wt% chlorine, 1-5 wt% sulfur, 1-10 wt% carbon, 20-40 wt% oxygen, 2-7 wt% sodium, 1-5 wt% potassium, 20-6000 ppm of heavy metals, and less than 15 wt% of other metallic elements; wherein the heavy metals include one or more of copper, lead, zinc, arsenic, manganese, nickel, chromium, or cadmium, and the other metallic elements include one or more of magnesium, iron, and aluminum.

[0009] Preferably, the copper slag contains 1-15 wt% copper, 2-5 wt% zinc, 20-40 wt% silicon, 20-40 wt% oxygen, 5-15 wt% iron, 5-10 wt% calcium, and other metallic elements totaling less than 10 wt%; wherein the other metallic elements include one or more of magnesium, aluminum, and sodium.

[0010] Preferably, the carbon-containing reducing agent is one or more of coke, pulverized coal, waste cathode carbon, or biochar.

[0011] Preferably, the amount of carbon-containing reducing agent added is 10 wt%-20 wt% of the mass of the smelting base material.

[0012] Preferably, before mixing the waste incineration fly ash, copper slag, and carbon-containing reducing agent into a smelting base material, the waste incineration fly ash is subjected to dechlorination treatment. Specifically, deionized water is used for dechlorination treatment, the liquid-to-solid ratio is 1:(2-20)L / kg, the treatment temperature is 20℃-50℃, the stirring rate is 150 r / min-200 r / min, and the treatment time is 20 min-40 min.

[0013] Preferably, the calcination temperature is 1250℃-1350℃ and the time is 1 h-2 h.

[0014] Preferably, the slag-liquid phase is rapidly cooled to obtain a vitrified product, wherein the rapid cooling is water quenching or air cooling.

[0015] Preferably, the content of amorphous phase in the vitrified product exceeds 85 wt%.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. The waste incineration fly ash disposal method provided by this invention utilizes the acid-base complementarity between the calcium component in the fly ash and the silicon component in the copper slag for roasting treatment. Compared with traditional fly ash vitrification or novel plasma melting processes, this method eliminates the need for external mineral additions, relying solely on the self-component compounding of raw materials for roasting. Simultaneously, by leveraging the differences in the physicochemical properties of each component under a reducing atmosphere, metallic copper or matte phases, due to their higher density, separate from the slag-liquid phase, achieving copper enrichment and the recovery of vitrification products. Therefore, this invention, by introducing copper slag as a synergistic flux into the smelting base material, eliminates the need for external mineral additives, while simultaneously improving the copper recovery rate and the quality of vitrification product recovery. This results in reduced waste incineration fly ash disposal costs and deep secondary resource recovery, demonstrating significant environmental and economic benefits.

[0017] 2. Due to the acid-base complementary fluxing effect between the calcium component in fly ash and the silicon component in copper slag, the eutectic temperature of the system can be reduced to the low liquidus temperature range, thereby reducing the calcination temperature. This reduces the high-temperature energy consumption in the waste incineration fly ash disposal process compared to calcining single fly ash materials (the method of the present invention can especially set the calcination temperature to 1250℃-1350℃).

[0018] 3. In this invention, the binary basicity of the smelting base material is preferably controlled to 0.5-1 by adjusting the compound ratio of waste incineration fly ash and copper slag. This is exactly near the lowest eutectic composition of the CaO-SiO2 binary system, maximizing the acid-base complementary fluxing effect and thus significantly reducing the melting temperature.

[0019] 4. The present invention preferably dechlorinates the fly ash from waste incineration before mixing and smelting the base material, thereby recovering the salt resources in the fly ash and effectively inhibiting the loss of copper due to chlorination volatilization during the smelting process.

[0020] 5. The waste incineration fly ash disposal method provided by this invention produces a melt that can be directly separated and recycled using density differences. Specifically, the denser, copper-rich liquid phase, after cooling, can be recycled as copper concentrate or crude copper products; the less dense amorphous silicate glass, after rapid cooling, yields a vitrified product with an amorphous phase content exceeding 85%, and heavy metal leaching toxicity lower than the technical requirements for vitrified products, allowing it to be directly used as building aggregate or environmentally friendly materials. Therefore, the disposal method of this application reduces the cost of waste incineration fly ash disposal while obtaining products with direct application value, achieving deep resource recycling. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a method for the co-melting and separation of copper and zinc from waste incineration fly ash and copper slag.

[0022] Figure 2 The diagram shows the ternary thermodynamic phase diagram of CaO-SiO2-Al2O3. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] To achieve the above objectives, the following solutions are provided: A method for the co-melting and separation of copper and zinc from waste incineration fly ash and copper slag is provided, such as... Figure 1 As shown, it includes the following steps: Waste incineration fly ash, copper slag, and carbon-containing reducing agent are uniformly mixed as smelting base material and roasted. The melt produced by roasting is separated into a copper-rich liquid phase and a slag-liquid phase by standing and using density difference. Then, the copper-rich liquid phase is cooled to obtain a copper-rich product, and the slag-liquid phase is cooled to obtain a vitrified product.

[0025] Preferably, the binary basicity of the smelting base is 0.5-1. In this invention, the binary basicity of the smelting base is the mass ratio of CaO to SiO2, specifically representing the proportion of waste incineration fly ash and copper slag in the smelting base. R The calculation formula is: binary alkalinity ( R )= w (CaO) / w (SiO2), This indicates the mass fraction of the component.

[0026] It should be noted that the relatively high calcium content in waste incineration fly ash does not occur in its elemental form, but rather in various compound forms. Common calcium-containing mineral phases include: calcium oxide (CaO), calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3), calcium sulfate (CaSO4), calcium chloride (CaCl2) and its hydroxyl compounds (CaClOH), and various calcium silicates (such as CaSiO3). Furthermore, the calcium in fly ash mainly comes from two sources: flue gas deacidification (in waste incineration flue gas purification systems, large amounts of slaked lime or limestone slurry are typically injected for neutralization to remove acidic gases (such as HCl and SO2), and small amounts of calcium-containing substances inherent in the waste itself, such as discarded gypsum board and eggshells. Copper slag contains a large amount of silicon, which is a skeletal element constituting the copper slag. The specific chemical composition and silicon content of copper slag vary slightly due to different smelting processes and raw materials. Silicon units mainly exist in the form of silicon oxide, but not entirely as silicon dioxide; rather, they exist primarily in the form of compounds (the most important mineral phase is fritillary olivine (Fe₂SiO₄), and may also exist as glassy silicates (amorphous phase), copper silicate, sodium aluminum silicate, etc.). Furthermore, copper slag also contains zinc, but its content varies considerably depending on the source of raw materials, smelting process, and slag treatment procedures.

[0027] Preferably, the fly ash from waste incineration comprises calcium, silicon, chlorine, sulfur, carbon, oxygen, sodium, potassium, heavy metals, and other metallic elements. The heavy metals include one or more of copper, lead, zinc, arsenic, manganese, nickel, chromium, or cadmium, while the other metallic elements include one or more of magnesium, iron, and aluminum. Furthermore, the calcium content is 20-40 wt%, the chlorine content is 5-20 wt%, the sulfur content is 1-5 wt%, the carbon content is 1-10 wt%, the oxygen content is 20-40 wt%, the sodium content is 2-7 wt%, the potassium content is 1-5 wt%, the heavy metal content is 20-6000 ppm (i.e., 0.002 wt%-0.6 wt%), the total amount of other metallic elements is less than 15 wt%, and the remainder is unavoidable impurities.

[0028] Preferably, the copper slag comprises copper, zinc, silicon, oxygen, iron, calcium, and other metallic elements; wherein the other metallic elements include magnesium, aluminum, and sodium. Furthermore, the copper content is 1-15 wt%, the zinc content is 1-5 wt%, the silicon content is 20-40 wt%, the oxygen content is 20-40 wt%, the iron content is 5-15 wt%, the calcium content is 5-10 wt%, and the total amount of other metallic elements is less than 10 wt%, with the remainder being unavoidable impurities.

[0029] During the roasting process, such as Figure 2 As shown, the fly ash and copper slag from waste incineration utilize the complementary acid-base components of calcium (alkaline) and silicon (acidic) to adjust the binary alkalinity, keeping the system in the low liquidus temperature range. Simultaneously, other elements in the fly ash and copper slag (such as chlorine, sulfur, carbon, and oxygen) participate in the reaction at high temperatures. Chlorine promotes the volatilization of heavy metals (such as zinc and lead), carbon maintains the reducing atmosphere, and metal elements (such as copper, zinc, and lead) undergo selective separation based on their vapor pressure difference and oxophilic / sulfophilic properties: volatile metals such as zinc and lead enter the flue gas in the form of chlorides or elemental forms, and are collected by dust removal to obtain zinc-rich flue gas dust; sulfophilic / chalcophilic metals such as copper are reduced by carbon and enriched in the heavy copper-rich liquid phase (matte or crude copper), thus achieving efficient separation and recovery of copper and zinc.

[0030] Preferably, the carbon-containing reducing agent is one or more of coke, pulverized coal, waste cathode carbon or biochar, and its addition amount is between 10 w% and 20 w% (based on the total mass of the smelting base material).

[0031] Preferably, before mixing the waste incineration fly ash, copper slag, and carbon-containing reducing agent into the smelting base material, the waste incineration fly ash is further subjected to dechlorination treatment to ensure that the chlorine content in the waste incineration fly ash after water washing is less than 2 wt%. Specifically, the dechlorination treatment involves using deionized water at a liquid-to-solid ratio of 1:(2-20) L / kg, a water washing temperature of 20℃-50℃, a stirring rate of 150 r / min-200 r / min, and a water washing time of 20 min-40 min, until the chlorine content of the fly ash after water washing is less than 2 wt%. Figure 1 As shown, in a complete treatment system, the washing liquid after dechlorination is evaporated and condensed for reuse.

[0032] Preferably, the calcination melting temperature is 1250℃-1350℃, and the calcination time is 1 h-2 h.

[0033] Preferably, when the copper slag used has a high zinc content, zinc-containing dust is obtained by collecting the flue gas generated during the roasting process. During roasting, zinc, a low-boiling-point metal, is reduced and volatilizes into the flue gas. After being collected by the dust collection system, the flue gas becomes zinc-rich dust. An example dust collection process is as follows: high-temperature flue gas is first cooled through a cooling pipe with a settling hopper at the bottom. Large particles entrained in the flue gas settle here, preventing them from entering subsequent equipment and causing blockages. The flue gas then enters a cyclone separator (vortex dust collector), where centrifugal force separates the heavier solid particles from the gas. The large particles in the dust are returned to the roasting unit, while the lighter dust with a higher zinc content enters the downstream equipment with the airflow. The zinc-containing dust, after cyclone separation, enters a bag filter, where gas-solid separation is achieved through filter bag filtration. The dust is captured on the surface of the filter bags, and the purified gas is discharged in compliance with standards. If the collected dust contains 45%-55% zinc, it is considered zinc-rich dust and can be used as zinc oxide or zinc oxide products. For higher dust collection efficiency, wet dust collection systems such as venturi tube-intercooler-or-dynamic wave-electrostatic precipitator can be used for more thorough dust collection.

[0034] Preferably, the melt produced during roasting is separated into a copper-rich liquid phase and a slag-liquid phase by utilizing the density difference during settling. Specifically, after melting, the melt enters a static state and naturally separates into two layers under gravity: the upper layer is a lighter slag-liquid phase, and the lower layer is a denser copper-rich liquid phase. After settling, the lower copper-rich liquid phase is first discharged from the bottom of the furnace and naturally cooled to obtain a heavy copper-rich product. Then, the upper slag-liquid phase is discharged from the slag outlet and rapidly cooled by water quenching or air cooling to obtain a light vitrified product. The heavy copper-rich product is a dense metallic copper or matte phase with a high copper content, which can be recycled as copper concentrate or crude copper product. The vitrified product is a low-density amorphous silicate glass with a dense structure and good chemical stability, which can be used as building material aggregate or environmentally friendly material.

[0035] More preferably, the slag-liquid phase is cooled by air to obtain vitrified products, thus avoiding water pollution.

[0036] Preferably, the vitrified product has an amorphous phase content of more than 85% and a heavy metal leaching toxicity lower than the technical requirements for vitrified products (GB 41015-2021).

[0037] The principle of this invention is as follows: The fly ash from waste incineration contains a high content of calcium components (mainly alkaline oxide CaO), and its melting point usually exceeds 1600℃ when treated alone. Copper slag is rich in silicon components (mainly acidic oxide SiO2). This invention utilizes the complementarity of the acid and base components of the two, and adjusts the binary alkalinity through reasonable compounding to keep the system in the low liquidus temperature range. Furthermore, the SiO2 in the molten state forms a stable glass skeleton, allowing residual heavy metals to enter the amorphous silicate network through displacement or interstitial filling. During the eutectic process, metallic copper and zinc undergo the following reduction reactions (1)–(3) under the action of the reducing agent, forming metallic copper, matte, and metallic zinc. While reducing copper and zinc, it is necessary to suppress the excessive reduction of a large amount of iron oxide in the copper slag to maintain the low melting point and good fluidity of the metallic phase. Since the density of copper alloy and matte is higher than that of silicate slag, they sink to the bottom under gravity, forming a heavy copper-rich phase to achieve recovery. After cooling, the silicate slag forms a light and stable glass slag. The reduced product, elemental zinc, volatilizes from the melt into the gas phase due to its high vapor pressure and is eventually captured as zinc-containing dust, thus achieving efficient separation and recovery of copper and zinc.

[0038] The reduction reaction involved in this invention is as follows: Cu₂O + C = 2Cu + CO(g) (1) ZnO + C = Zn(g) + CO(g) (2) CaSO4+ 4C + Cu2O = Cu2S + CaO + 4CO(g)(3) The following description, in conjunction with specific embodiments and accompanying drawings, further illustrates the solution of this application.

[0039] The main components of fly ash, copper slag, and carbon-containing reducing agent in the following embodiments of the present invention are described below: The calcium content in the fly ash from waste incineration was 28.46 wt% as measured by X-ray fluorescence spectrometry, the chlorine content was 10.76 wt% as measured by automatic potentiometric titration, the sulfur and carbon contents were 2.02 wt% and 1.92 wt% as measured by elemental analyzer, respectively, and the heavy metal content was 30-5000 ppm as measured by inductively coupled plasma atomic emission spectrometry. The remaining components were mainly oxygen and trace impurities.

[0040] The silicon content in the copper slag was 26.14 wt% as measured by X-ray fluorescence spectrometry, while the copper and zinc contents were 13.62 wt% and 4.11 wt% as measured by inductively coupled plasma atomic emission spectrometry, respectively. The sulfur content was 0.77 wt% as measured by elemental analysis. The remaining components were mainly oxygen and trace impurities.

[0041] The carbon-containing reducing agent uses coke powder, and the fixed carbon content is 85.69 wt% as measured by an industrial analyzer. The remaining components are mainly minerals (such as SiO2, Al2O3, Fe2O3, etc.) and moisture in the ash.

[0042] In the following examples, the copper and zinc recovery rates and the heavy metal leaching concentrations of the vitrified products were calculated as follows. The copper and zinc recovery rates were typically determined first by measuring the total amount of copper and zinc in the raw materials (incineration fly ash, copper slag) and products (copper-rich products, zinc-containing dust) using methods such as inductively coupled plasma optical emission spectrometry (ICP-OES), and then the recovery percentage was calculated. The heavy metal leaching concentrations of the vitrified products were determined according to GB / T 41015 standard. The samples were prepared using the HJ 557 horizontal oscillation method (solid-liquid ratio 1:10 L / kg, oscillation frequency 110 ± 10 times per minute, deionized water, oscillation at room temperature for 8 hours) to obtain the leachate. The concentrations of each heavy metal were analyzed using ICP-MS or ICP-OES, and finally compared with the standard limits.

[0043] Example 1: (1) The selected waste incineration fly ash was subjected to water washing and dechlorination treatment so that the chlorine content of the fly ash after water washing was less than 2 wt%; (2) The washed waste incineration fly ash and copper slag are mixed at a ratio of 0.8 for binary basicity CaO / SiO2, and 15 wt% of coke powder is added to the total mass of the smelting base material. (3) The smelting base material is fed into the smelting furnace and smelted at 1350℃ for 2 h. The melt produced by roasting is separated into a copper-rich liquid phase and a slag liquid phase by using the density difference. The copper-rich liquid phase is then cooled to obtain a copper-rich product, and the slag liquid phase is cooled to obtain a vitrified product. In addition, the flue gas generated during the roasting process is collected to obtain zinc-containing dust.

[0044] Example 2: (1) The selected waste incineration fly ash was subjected to water washing and dechlorination treatment so that the chlorine content of the fly ash after water washing was less than 2 wt%; (2) The washed waste incineration fly ash and copper slag are mixed at a ratio of 0.5 for binary basicity CaO / SiO2, and 15 wt% of coke powder is added to the total mass of the smelting base material. (3) The smelting base material is fed into the smelting furnace and smelted at 1350℃ for 2 h. The melt produced by roasting is separated into a copper-rich liquid phase and a slag liquid phase by using the density difference. The copper-rich liquid phase is then cooled to obtain a copper-rich product, and the slag liquid phase is cooled to obtain a vitrified product. In addition, the flue gas generated during the roasting process is collected to obtain zinc-containing dust.

[0045] Example 3: (1) The selected waste incineration fly ash was subjected to water washing and dechlorination treatment so that the chlorine content of the fly ash after water washing was less than 2 wt%; (2) The water-washed waste incineration fly ash and copper slag are mixed in a ratio of 1 for binary basicity CaO / SiO2, and 15 wt% of coke powder is added to the total mass of the smelting base material. (3) The smelting base material is fed into the smelting furnace and smelted at 1350℃ for 2 h. The melt produced by roasting is separated into a copper-rich liquid phase and a slag liquid phase by using the density difference. The copper-rich liquid phase is then cooled to obtain a copper-rich product, and the slag liquid phase is cooled to obtain a vitrified product. In addition, the flue gas generated during the roasting process is collected to obtain zinc-containing dust.

[0046] Comparative Example 1: The treatment steps and implementation parameters are the same as in Example 1, except that in step (2), the material ratio is adjusted so that the binary alkalinity CaO / SiO2 is 0.2.

[0047] Comparative Example 2: The treatment steps and implementation parameters are the same as in Example 1, except that in step (2), the material ratio is adjusted so that the binary alkalinity CaO / SiO2 is 1.5.

[0048] The copper and zinc recovery rates measured according to Examples 1-3 and Comparative Examples 1-2 are shown in Table 1, and the leaching concentrations of heavy metals in the vitrified products are shown in Table 2.

[0049] Table 1. Copper and Zinc Recovery Rates (%)

[0050] Table 2. Heavy metal leaching concentrations (mg / L) in vitrified products

[0051] ND: Not detected As can be seen from Tables 1 and 2, the method for co-melting and recovering copper and zinc from waste incineration fly ash and copper slag provided in this application has the following effects on the copper and zinc recovery rates and the heavy metal leaching concentration in the smelting slag in step (2): When the binary basicity CaO / SiO2 is between 0.5 and 1, the copper and zinc recovery rates are relatively high, exceeding 90% and 80% respectively, while the heavy metal leaching concentration in the smelting slag is relatively low, both below the glass transition standard. If the binary basicity is too low or too high, the slag melting point will increase, making it difficult to melt and form a stable glass phase, further resulting in copper and zinc recovery rates below 90% and 80% respectively, excessive copper leaching concentration in the smelting slag, and small amounts of zinc, lead, and chromium leaching.

[0052] Example 4: The treatment steps and implementation parameters are the same as in Example 1, except that in step (2), the amount of coke powder added is adjusted to 10wt%.

[0053] Example 5: The treatment steps and implementation parameters are the same as in Example 1, except that in step (2), the amount of coke powder added is adjusted to 20wt%.

[0054] Comparative Example 3: The treatment steps and implementation parameters are the same as in Example 1, except that in step (2), the amount of coke powder added is adjusted to 5 wt%.

[0055] Comparative Example 4: The treatment steps and implementation parameters are the same as in Example 1, except that in step (2), the amount of coke powder added is adjusted to 25 wt%.

[0056] The copper and zinc recovery rates measured according to Examples 1, 4-5 and Comparative Examples 3-4 are shown in Table 3, and the heavy metal leaching concentrations in the vitrified products are shown in Table 4.

[0057] Table 3 Copper and Zinc Recovery Rates (%)

[0058] Table 4. Heavy metal leaching concentrations (mg / L) in vitrified products

[0059] ND: Not detected As can be seen from Tables 3 and 4, the method for co-melting and recovering copper and zinc from waste incineration fly ash and copper slag provided in this application has the following effects on the copper and zinc recovery rate and the heavy metal leaching concentration in the smelting slag in step (2): When the coke powder addition is between 10wt% and 20wt%, the copper and zinc recovery rates are relatively high, exceeding 90% and 80% respectively, while the heavy metal leaching concentration in the smelting slag is relatively low, all below the vitrification standard. When the coke powder addition is too low, the carbon-containing reducing agent is insufficient to reduce the high-valence metals, resulting in copper and zinc recovery rates below 70% and 40% respectively, and the copper and zinc leaching concentrations in the smelting slag exceed the standard, with small amounts of lead, chromium, manganese, arsenic, and nickel leaching out; when the coke powder addition is too high, a large amount of high-valence iron is reduced into the copper alloy phase, leading to an increase in the alloy melting point, making it difficult to melt, aggregate, and recover, resulting in a copper recovery rate below 85%, and the copper leaching concentration in the smelting slag exceeds the standard, with small amounts of lead, chromium, and nickel leaching out.

[0060] Example 6: The processing steps and implementation parameters are the same as in Example 1, except that in step (3), the melting temperature is adjusted to 1250°C.

[0061] Example 7: The processing steps and implementation parameters are the same as in Example 1, except that in step (3), the melting temperature is adjusted to 1350°C.

[0062] Comparative Example 5: The processing steps and implementation parameters are the same as in Example 1, except that in step (3), the melting temperature is adjusted to 1250°C.

[0063] Comparative Example 6: The processing steps and implementation parameters are the same as in Example 1, except that in step (3), the melting temperature is adjusted to 1400°C.

[0064] The copper and zinc recoveries measured according to Examples 1, 6-7 and Comparative Examples 5-6 are shown in Table 5. The heavy metal leaching concentrations in the vitrified products are shown in Table 6. Table 5. Copper and Zinc Recovery Rates (%)

[0065] Table 6. Heavy metal leaching concentrations (mg / L) in vitrified products

[0066] ND: Not detected As can be seen from Tables 5 and 6, the method for co-melting and recovering copper and zinc from waste incineration fly ash and copper slag provided in this application has the following effects on the copper and zinc recovery rates and the heavy metal leaching concentration in the slag: When the temperature is between 1250℃ and 1350℃, the copper and zinc recovery rates are relatively high, exceeding 90% and 80% respectively, while the heavy metal leaching concentration in the slag is low, all below the vitrification standard. When the temperature is too low, the material as a whole is not melted, and the copper and zinc recovery rates are below 40% and 65% respectively. The leaching concentrations of copper, zinc, and lead in the slag exceed the standard, and a small amount of chromium, manganese, arsenic, and nickel are leached. When the temperature is too high, a large amount of high-valence iron is reduced into the copper alloy phase, resulting in an increase in the alloy melting point, making it difficult to melt, aggregate, and recover, resulting in a copper recovery rate below 80%, a copper leaching concentration exceeding the standard in the slag, and a small amount of nickel being leached.

[0067] Comparative Example 7: The treatment steps and implementation parameters are the same as in Example 1, except that the water washing and dechlorination in step (1) are not performed, and the original fly ash and copper slag are directly mixed and smelted.

[0068] Table 7 Copper and Zinc Recovery Rates (%)

[0069] Table 8. Heavy metal leaching concentrations (mg / L) in vitrified products

[0070] ND: Not detected As can be seen from Tables 7 and 8, the method for co-melting and recovering copper and zinc from waste incineration fly ash and copper slag provided in this application has the following effects on the copper and zinc recovery rates and the heavy metal leaching concentration in the smelting slag: After fly ash is washed and dechlorinated, the copper and zinc recovery rates are relatively high when co-melted with copper slag, exceeding 90% and 80% respectively. The heavy metal leaching concentration in the smelting slag is low, both below the vitrification standard. When fly ash is directly co-melted with copper slag, the presence of chlorine causes copper to form gaseous chlorides that volatilize into the flue gas, preventing enrichment in the bottom alloy phase, thus resulting in a copper recovery rate below 90%. The heavy metal leaching concentration in the smelting slag is also below the vitrification standard.

[0071] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for disposing of fly ash from waste incineration, characterized in that, include: Waste incineration fly ash, copper slag, and carbon-containing reducing agent are mixed as smelting base material and roasted. The melt produced by roasting is separated into a copper-rich liquid phase and a slag-liquid phase by standing and using density difference. Then, the copper-rich liquid phase is cooled to obtain a copper-rich product, and the slag-liquid phase is cooled to obtain a vitrified product.

2. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The binary basicity of the smelting base material is 0.5-1.

3. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The incineration fly ash contains 20-40 wt% calcium, 1-10 wt% silicon, 5-20 wt% chlorine, 1-5 wt% sulfur, 1-10 wt% carbon, 20-40 wt% oxygen, 2-7 wt% sodium, 1-5 wt% potassium, 20-6000 ppm of heavy metals, and less than 15 wt% of other metallic elements; wherein the heavy metals include one or more of copper, lead, zinc, arsenic, manganese, nickel, chromium, or cadmium, and the other metallic elements include one or more of magnesium, iron, and aluminum.

4. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The copper slag contains 1-15 wt% copper, 2-5 wt% zinc, 20-40 wt% silicon, 20-40 wt% oxygen, 5-15 wt% iron, 5-10 wt% calcium, and less than 10 wt% other metallic elements; wherein the other metallic elements include one or more of magnesium, aluminum, and sodium.

5. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The carbon-containing reducing agent is one or more of coke, pulverized coal, waste cathode carbon, or biochar.

6. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The amount of carbon-containing reducing agent added is 10 wt%-20 wt% of the mass of the smelting base material.

7. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, Before mixing the waste incineration fly ash, copper slag, and carbon-containing reducing agent into the smelting base material, the waste incineration fly ash is subjected to dechlorination treatment. Specifically, deionized water is used for dechlorination treatment, the liquid-to-solid ratio is 1:(2-20)L / kg, the treatment temperature is 20℃-50℃, the stirring rate is 150 r / min-200 r / min, and the treatment time is 20 min-40 min.

8. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The roasting temperature is 1250℃-1350℃, and the time is 1 h-2 h.

9. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The copper-rich liquid phase is naturally cooled to obtain a copper-rich product; and the slag liquid phase is rapidly cooled to obtain a vitrified product, wherein the rapid cooling is water quenching or air cooling.

10. The method for disposing of fly ash from waste incineration according to claim 1, characterized in that, The vitrified product contains more than 85 wt% amorphous phase.

Images