Method for co-processing of waste incineration fly ash and lithium mine tailings

Abstract

The application discloses a kind of waste incineration fly ash and lithium ore tailings collaborative processing method, steps include: waste incineration fly ash and lithium ore tailings are mixed, and mixed material is obtained;Mixed material is mixed with alkaline activator, and is alkaline activated;After alkaline activation, mixed liquid is hydrothermally reacted, solid-liquid separation, and pretreatment liquid and pretreatment residue are obtained, and pretreatment product is obtained after water washing of pretreatment residue;Shale or coal gangue, sludge and pretreatment product are mixed, water is added, sintered, and collaborative processing of waste incineration fly ash and lithium ore tailings is completed.The lithium ore tailings used in the method of the application is a kind of porous material, has greater specific surface area and more reasonable silicon-aluminum-calcium ratio, which is beneficial to accelerate alkaline activation, improve the efficiency of hydrothermal reaction, the process steps are simple, the processing time is short, efficient, convenient, energy-saving, through the comprehensive treatment mode of "alkaline activation+hydrothermal pretreatment+sintering solidification", finally realizes the dual goal of waste treatment with waste and efficient solidification of heavy metals.

Description

Technical Field

[0001] This invention pertains to the field of waste incineration fly ash treatment technology, and particularly relates to a method for the co-treatment of waste incineration fly ash and lithium mine tailings. Background Technology

[0002] Waste incineration fly ash is generated during the waste incineration process. Generally speaking, 20-50 kg of fly ash is produced for every ton of waste incinerated. In particular, with the increasing volume of waste, the amount of fly ash generated after incineration is also constantly increasing. Therefore, the rapid disposal of waste incineration fly ash is an urgent technical problem that needs to be solved at present.

[0003] Currently, researchers have proposed methods to produce sintered bricks from waste incineration fly ash. This involves mixing fly ash with raw materials such as coal gangue, shale, and sludge, followed by aging, pressing, and firing to create fly ash sintered bricks. However, this method suffers from drawbacks such as long firing cycles, high energy consumption, and high costs. Furthermore, the resulting fly ash sintered bricks still exhibit excessive heavy metal leaching concentrations. Therefore, it is not only difficult to rapidly dispose of waste incineration fly ash through firing, but also hinders its resource-based reuse. Thus, effectively stabilizing heavy metals in waste incineration fly ash through firing and achieving its resource utilization is of great significance for facilitating the disposal of more waste incineration fly ash.

[0004] In order to achieve safe treatment of waste incineration fly ash, the existing safe treatment methods for waste incineration fly ash mainly include cement solidification, chemical stabilization, melt solidification technology, and wet chemical treatment. However, they have the following defects: (1) The stabilization effect on heavy metals is not ideal, or it is difficult to stabilize multiple heavy metals at the same time, or there is a risk of re-dissolution; (2) The required amount of chemicals is large, the cost is high and the technical requirements are high; (3) New wastewater, waste gas and waste residue are easily generated; (4) The curing cycle is long and it is difficult to dispose of a large amount of waste incineration fly ash; (5) The solidified body has a large volume increase ratio and requires a large amount of landfill space. Furthermore, existing methods for treating waste incineration fly ash using alkaline activation and hydrothermal treatment still have the following drawbacks: (a) high hydrothermal temperatures and long treatment durations are required, easily leading to high energy consumption, low efficiency, and high costs; (b) large reagent dosages are required, easily posing production safety risks, and reagent costs are high; (c) the stabilization effect on heavy metals is still unsatisfactory, requiring long-term curing to stabilize the heavy metals in the solidified body; (d) the fly ash solidified body obtained through existing alkaline activation and hydrothermal treatment methods is prone to heavy metal re-leaching during roasting, and is not conducive to improving the strength of the roasted product. Therefore, existing safe treatment methods for waste incineration fly ash still cannot ensure that the leaching concentration of heavy metals in the roasted product meets the standards.

[0005] Lithium mine tailings are waste residues generated during the lithium extraction process. Taking the spodumene-to-lithium salt production process as an example, approximately 8-10 tons of lithium slag are discharged for every ton of lithium salt produced. This high discharge rate results in a very high output of lithium waste residue, which not only occupies a large amount of land but also, if not properly stored, can lead to the loss of slag water containing alkalis, acids, and heavy metals, harming farmland and polluting the environment. Currently, the main methods for treating lithium mine tailings are stockpiling and landfilling, which easily leads to resource waste, environmental pollution, and geological risks. Therefore, reducing the environmental pollution risks of lithium mine tailings and achieving their rational utilization is of great significance.

[0006] To date, there have been no reports on the co-treatment of waste incineration fly ash and lithium mine tailings. Therefore, utilizing the co-treatment of waste incineration fly ash and lithium mine tailings to obtain a "waste-to-waste" method is of great significance for achieving the harmless and resource-based treatment of waste incineration fly ash and lithium mine tailings. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for the co-treatment of waste incineration fly ash and lithium mine tailings that is simple in process steps, short in processing time, and efficient, convenient and energy-saving in the whole process.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A method for co-treating fly ash from waste incineration and tailings from lithium mines includes the following steps:

[0010] S1. Mix the fly ash from waste incineration with lithium tailings to obtain a mixture;

[0011] S2. Mix the mixture with an alkaline activator and perform alkaline activation;

[0012] S3. The mixture after alkali activation is subjected to hydrothermal reaction, and solid-liquid separation is performed to obtain pretreated liquid and pretreated residue. The pretreated residue is washed with water to obtain pretreated product.

[0013] S4. Mix shale or coal gangue, sludge and the pretreated product, add water, and sinter to complete the co-treatment of waste incineration fly ash and lithium mine tailings.

[0014] In the above-mentioned method for co-treating fly ash from waste incineration and lithium tailings, preferably, in step S1, the lithium tailings contain Fe, Al, Si, and Ca, with the following mass percentages: Fe content is 1%–5%, Al content is 10%–30%, Si content is 55%–80%, and Ca content is 3%–10%.

[0015] In the above-mentioned method for co-treating waste incineration fly ash and lithium tailings, preferably, in step S1, the mass ratio of waste incineration fly ash to lithium tailings is 5 to 15:1.

[0016] In the above-mentioned method for co-treating waste incineration fly ash and lithium tailings, preferably, in step S1, the mass ratio of waste incineration fly ash to lithium tailings is 7.7 to 12.5:1.

[0017] In the above-mentioned method for co-treating fly ash from waste incineration and tailings from lithium mines, preferably, in step S2, the solid-liquid ratio of the mixture to the alkaline activator is 1g:1mL to 10mL, the concentration of the alkaline activator is 0.1mol / L to 1.0mol / L, and the alkaline activator is a NaOH solution.

[0018] In the above-mentioned method for co-treating fly ash from waste incineration and tailings from lithium mines, preferably, in step S3, the temperature of the hydrothermal reaction is 70℃~180℃, and the time of the hydrothermal reaction is 30min~60min.

[0019] In the above-mentioned method for co-treating fly ash from waste incineration and tailings from lithium mines, preferably, in step S4, the mass ratio of shale or coal gangue, sludge, and pretreated products is 6-9:1-3:0.5-2.

[0020] In the above-mentioned method for co-treating fly ash from waste incineration and lithium tailings, preferably, in step S4, the sintering temperature is 700℃~1150℃, the sintering time is 0.5~1.5h, and the sintering heating rate is 3℃ / min~10℃ / min.

[0021] In the above-mentioned co-treatment method of waste incineration fly ash and lithium tailings, preferably, in step S1, the waste incineration fly ash and lithium tailings need to be crushed and / or ground and sieved before mixing, and the particle size of the waste incineration fly ash and lithium tailings after sieving is ≤150μm.

[0022] In the above-mentioned method for co-treatment of waste incineration fly ash and lithium tailings, preferably, in step S1, the incineration fly ash and lithium tailings are mixed by stirring, the stirring speed is 50 r / min to 500 r / min, and the stirring time is 3 min to 10 min.

[0023] In the above-mentioned method for co-treating fly ash from waste incineration and tailings from lithium mines, preferably, in step S2, the alkaline activation involves mixing the mixture with an alkaline activator and then allowing it to stand for 3 to 20 minutes.

[0024] In the above-mentioned co-treatment method for waste incineration fly ash and lithium tailings, preferably, in step S3, the pretreatment liquid is returned as a reaction medium to the hydrothermal reaction in step S2, and the washing liquid generated by the water washing is returned as a reaction medium to the hydrothermal reaction in step S2.

[0025] In the above-mentioned co-treatment method for waste incineration fly ash and lithium tailings, preferably, in step S4, the amount of water added is 12% to 20% of the total mass of the solid raw materials (i.e., a mixture of shale or coal gangue, sludge and pre-treated products).

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] (1) This invention provides a method for the co-treatment of waste incineration fly ash and lithium ore tailings. Using waste incineration fly ash and lithium ore tailings as raw materials, compared to conventional heavy metal stabilizers or composite silica-alumina modifiers (including fly ash and diatomaceous earth), the lithium ore tailings used in this invention are porous materials with a larger specific surface area. Furthermore, they contain Fe, Al, Si, and Ca, with the following mass percentages: Fe content 1%–5%, Al content 10%–30%, Si content 55%–80%, and Ca content 3%–10%. Therefore, the proportion of silica, aluminum, and calcium is significantly higher. The method is reasonable, therefore, when the mixture of lithium tailings and waste incineration fly ash is placed in an alkaline environment, the alkaline activator can quickly penetrate into the interior of the lithium tailings, thus undergoing rapid dissolution under the activation of the alkaline activator. This allows more silicon, aluminum, and calcium elements to dissolve into the system. Furthermore, during the hydrothermal reaction, the silicon, aluminum, and calcium elements in the system can rapidly form more calcium silicates, aluminates, and aluminosilicates gels. Simultaneously, the fixation effect of these gels can quickly fix heavy metals in the waste incineration fly ash and lithium tailings. In particular, due to the aforementioned advantages of lithium tailings, the alkaline activation in this invention only requires 3 to 20 minutes, and the hydrothermal reaction only needs to be carried out at a temperature of 70°C to 180°C for 30 to 60 minutes to achieve effective fixation of heavy metals. The reaction conditions are mild, significantly shortening the overall process time and reducing energy consumption. This also makes the raw material selectivity of this invention higher, the fault tolerance higher, and the controllability stronger. Based on this, the gel mixture formed after hydrothermal treatment is used as a curing agent and mixed with shale or coal gangue and sludge before calcination. The content of heavy metals to be cured in the product (solidified fly ash) after alkali activation and hydrothermal pretreatment is significantly reduced, making it suitable as a raw material for preparing sintered bricks (shale bricks). Simultaneously, when sintered with other raw materials, heavy metals can be cured again during the sintering process, and sintering can be completed in only 0.5–1.5 hours, resulting in a faster rate of heavy metal curing and shortening production time. This allows for the rapid and effective fixation of heavy metals in waste incineration fly ash and lithium tailings, meeting relevant requirements. Furthermore, during high-temperature sintering, mineral elements such as Si and Ca in lithium tailings combine or complex with heavy metal elements in fly ash to form stable metal compounds, thereby reducing the risk of heavy metal leaching from fly ash and minimizing environmental harm. Ultimately, this achieves the dual goals of waste-to-waste treatment, efficient curing, and slow release of heavy metals.Compared with existing conventional methods, the co-treatment method of waste incineration fly ash and lithium ore tailings of this invention uses waste incineration fly ash and lithium ore tailings as raw materials and adopts a comprehensive treatment method of "alkaline activation + hydrothermal pretreatment + sintering and solidification". It can utilize lithium ore tailings to slowly release heavy metals in fly ash matrix shale bricks, and can achieve the dual goals of waste treatment, efficient solidification and slow release of heavy metals. It has the advantages of simple steps, convenient operation, low cost, short cycle, good stabilization effect, environmental protection and energy saving. It can quickly prepare shale bricks from waste incineration fly ash and lithium ore tailings, which is of great significance for realizing the harmless treatment and resource utilization of waste incineration fly ash and lithium ore tailings.

[0028] (2) In this invention, by optimizing the mass ratio of waste incineration fly ash to lithium tailings to 5-15:1, and especially optimizing the mass ratio to 7.7-12.5:1, the amount of both is more scientific, which is conducive to promoting the participation of various effective components in waste incineration fly ash and lithium tailings in alkali activation and hydrothermal reaction. By promoting the participation of as many effective components as possible in the reaction, the reaction is more complete and faster, and the solidification effect is better. As the main raw material of the co-treatment method of this invention, if the amount of lithium tailings is too low, it is not conducive to effectively coordinating and solidifying the heavy metals in the fly ash. Moreover, the amount of lithium tailings is not necessarily better the higher it is, because it also contains heavy metals, such as its high As content. Therefore, if the amount of lithium tailings is too high, it is easy to cause the sum of the heavy metals in the lithium tailings and the heavy metals in the fly ash to exceed the capacity of the co-treatment method of this invention. Therefore, the amount of lithium tailings must be limited to a reasonable range.

[0029] (3) In this invention, by optimizing the mass ratio of shale or coal gangue, sludge and hydrothermal products to 6-9:1-3:0.5-2, it is beneficial to rationally control the proportion of hydrothermal products in the sintering mixture. This can take into account the resource utilization and harmless treatment of fly ash and lithium tailings while saving the amount of auxiliary material shale or coal gangue, which is equivalent to increasing the amount of fly ash and lithium tailings consumed. Attached Figure Description

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0031] Figure 1 This is a process flow diagram of the co-treatment of waste incineration fly ash and lithium tailings in Embodiment 1 of the present invention.

[0032] Figure 2 This is a process flow diagram of the waste incineration fly ash treatment in Comparative Example 3 of the present invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0034] In the following examples, unless otherwise specified, the raw materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0035] Example 1:

[0036] The present invention discloses a method for co-treating fly ash from waste incineration and tailings from lithium mines, the process flow of which is as follows: Figure 1 As shown, it includes the following steps:

[0037] S1. Weigh 3.6g of waste incineration fly ash, sieve, grind, and sieve to obtain fly ash with a particle size ≤150μm. Weigh 0.4g of lithium tailings, dry, crush, and sieve to obtain lithium tailings with a particle size ≤150μm. Mix the sieved incineration fly ash and lithium tailings through a mixer to obtain a mixture. The mixing speed during the mixing process is 100r / min, and the mixing time is 5min.

[0038] The lithium tailings contain Fe, Al, Si, and Ca. By mass percentage, the Fe content is 1%–5%, the Al content is 10%–30%, the Si content is 55%–80%, and the Ca content is 3%–10%. Specifically, in this embodiment, the lithium tailings contain 2.3% Fe, 16.3% Al, 67.3% Si, and 5.6% Ca.

[0039] S2. Add the mixture into the hydrothermal reactor at a liquid-to-solid ratio of 9 mL:1 g. Add a 0.5 mol / L alkaline activator (NaOH solution) to the mixture and let it stand for 10 min for activation. Seal the hydrothermal reactor after filling and place it in an oven to heat it. Perform a hydrothermal reaction at 150°C for 45 min.

[0040] Using NaOH solution as an alkaline activator offers several advantages: NaOH is readily available, has high alkalinity, contains only Na (a single metallic element), and is highly efficient, free of impurities, and low in cost. During the alkaline activation process, the reaction can be allowed to stand still, or external forces (such as shaking) can be applied to shorten the activation time.

[0041] S3. After the reaction is complete and cooled to room temperature, open the reactor and vacuum filter the hydrothermal reaction product to separate the solid and liquid, obtaining a pretreated liquid and a pretreated residue. After washing with water, the pretreated residue is placed in an oven and dried at 105°C for 30 minutes to obtain the pretreated product.

[0042] In this step, the pretreated liquid obtained by vacuum filtration (i.e., the first filtration) of the hydrothermal reaction product is used for other resource recovery processes, such as returning it to the hydrothermal reaction in step S2 as a reaction medium. At this time, the pretreated liquid is still relatively alkaline, and the loss from one round of hydrothermal reaction is small. Compared with the pre-reaction liquid, only some heavy metals are added. Recycling can save alkaline activator without affecting the alkaline activation effect. The pretreated residue is rinsed twice with clean water and filtered (i.e., the second and third filtration). The clean water can be deionized water or tap water. The washing liquid from the second and third filtrations is collected and reused in the next hydrothermal reaction process and can be used as a solvent to prepare the alkaline activator.

[0043] S4. Shale is crushed and sieved; municipal sludge is deodorized, dried, crushed, and sieved. The sieved sludge and sludge are mixed with the pretreated product at a mass ratio of 7:2:1 and added to a mold. Specific dosages are shown in Table 1. Water (15% of the total solid mass) is added and mixed thoroughly. The mixture is then extruded, dried, and sintered at a rate of 5℃ / min to 950℃. Figure 1 The shale bricks were produced by co-processing waste incineration fly ash and lithium tailings by roasting for 1 hour.

[0044] Example 2:

[0045] The present invention provides a method for co-treating fly ash from waste incineration and tailings from lithium mines. The process steps are basically the same as those in Example 1. The main difference is that in step S4 of this example, the mass ratio of shale, sludge and pretreatment product is 8.5:1:0.5, and the specific amounts are shown in Table 1.

[0046] Table 1. Raw material ratios for Examples 1 and 2

[0047] Ratio Shale (g) Sludge (g) Pretreated product (g) Total weight (g) Example 1 7∶2∶1 14.002 4.002 2.001 20.005 Example 2 8.5∶1∶0.5 17.002 2.004 1.001 20.007

[0048] Comparative Example 1:

[0049] A method for treating fly ash from waste incineration has the same process steps as step S4 in Example 1. The main difference is that the pre-treated product is replaced with pure fly ash, i.e. fly ash that has not been treated by alkali activation and hydrothermal reaction. The specific amount is shown in Table 2. Other conditions remain unchanged. Two parallel tests are conducted, and the brick samples obtained are denoted as A1 and A2, respectively.

[0050] Comparative Example 2:

[0051] A method for treating fly ash from waste incineration has the same process steps as step S4 in Example 2. The main difference is that the pre-treated product is replaced with pure fly ash, i.e. fly ash that has not been treated by alkali activation and hydrothermal reaction. The specific amount is shown in Table 2. Other conditions remain unchanged. Two parallel tests are conducted, and the brick samples obtained are denoted as B1 and B2, respectively.

[0052] Table 2 Raw material ratios for Comparative Example 1 and Comparative Example 2

[0053]

[0054] Leaching heavy metal test:

[0055] The fly ash that has not undergone alkali activation and hydrothermal reaction treatment, i.e., pure fly ash, was subjected to leaching experiments according to the "Leaching Toxicity of Solid Waste - Horizontal Oscillation Method" (HJ 557-2010). The leaching concentrations of the main heavy metals obtained are shown in Table 3.

[0056] The same leaching experiments were performed on the sample bricks prepared in Comparative Example 1 and Comparative Example 2 according to the same procedure. The leaching concentrations of the main heavy metals obtained are shown in Table 4.

[0057] The shale bricks prepared in Examples 1 and 2 were subjected to the same leaching experiments according to the same procedures, and the leaching concentrations of the main heavy metals obtained are shown in Table 5.

[0058] Table 3. Leaching concentrations of major heavy metals from pure fly ash (ug / L)

[0059]

[0060]

[0061] Table 1-3 shows fly ash samples taken directly from factory waste incineration. Due to batch variations, the heavy metal content in these fly ash samples varies, which is normal. Consequently, the concentration of heavy metals in the leachate from each fly ash sample also differs, which is also normal. In particular, the varying heavy metal content in different fly ash samples increases the difficulty of fly ash treatment and can easily lead to significant differences in the solidification effect of heavy metals after treatment with the same process on different batches of samples. Some batches may meet the standards, while others may not, indicating poor process tolerance. To address these shortcomings, this invention employs a comprehensive treatment method of "alkaline activation + hydrothermal pretreatment + sintering solidification," which has strong solidification capabilities for heavy metals, can control the heavy metal leaching concentration in the treated fly ash at a low level, and has high tolerance, thus effectively overcoming the treatment difficulties caused by differences in fly ash samples from different batches.

[0062] Table 4. Leaching concentrations of major heavy metals (ug / L) in the brick samples prepared for Comparative Example 1 and Comparative Example 2.

[0063]

[0064] Table 5. Leaching concentrations of major heavy metals in the sample bricks prepared in Examples 1 and 2 (ug / L)

[0065] Ratio Cr Ni Cu Zn As Cd Hg Pb Example 1 7∶2∶1 928.0 18.0 88.0 436.1 5.7 0.9 1.2 116.3 Example 2 8.5∶1∶0.5 957.5 16.0 52.0 502.1 4.3 0.8 0.3 65.0

[0066] Comparing the results in Tables 4 and 5, it can be seen that, under the same conditions, the leaching concentrations of various heavy metals in shale bricks prepared by the co-treatment method of waste incineration fly ash and lithium tailings according to the present invention are significantly reduced, and all meet the leaching concentration requirements of heavy metals in shale bricks in the integrated wastewater discharge standard.

[0067] Comparative Example 3:

[0068] A method for the co-processing of waste incineration fly ash and recycled micro powder, the process flow is as follows: Figure 2 As shown, it includes the following steps:

[0069] S1. Deodorize, dry, crush, and sieve the municipal sludge; crush and sieve the shale; sieve, grind, and sieve the waste incineration fly ash (same as in Example 1); crush and sieve the recycled micro powder; after sieving the above raw materials, the particle size is ≤150μm. Weigh the sieved shale, sludge, fly ash, and recycled micro powder in a mass ratio of 6∶1∶1∶2 and mix them evenly to obtain 20.0g of mixture. The specific amount used is shown in Table 6. Figure 2 Other auxiliary materials refer to recycled micro powder or lithium tailings. Recycled micro powder is produced during the process of recycling aggregates from construction waste, and can also be obtained through commercial purchase.

[0070] S2. Add the mixture from step S1 into the quartz boat, spread it evenly, and press it against the wall of the quartz boat. Add water at a mass of 18% of the total solid mass, i.e., 3.6 ml of water.

[0071] S3. Place the quartz boat into a muffle furnace and heat it to 950°C at a rate of 5°C / min for sintering (i.e., Figure 2 (Bake in the oven) for 1 hour to obtain brick samples.

[0072] Comparative Example 4:

[0073] A method for co-processing fly ash from waste incineration and recycled micro powder has the same process steps as Comparative Example 3, except that different mass ratios of raw materials are used. Specifically, the mass ratio of sieved shale, sludge, fly ash, and recycled micro powder is 6.5:1.5:1:1. The specific amounts are shown in Table 6.

[0074] Comparative Example 5:

[0075] A method for co-processing fly ash from waste incineration and lithium tailings is provided. The process steps are basically the same as those in Comparative Example 3, except that the recycled micro powder is replaced with lithium tailings, and the mass ratio of sieved shale, sludge, fly ash and lithium tailings is 6:2:1:1. The specific amounts are shown in Table 6.

[0076] Comparative Example 6:

[0077] A method for co-processing fly ash from waste incineration and lithium tailings is provided. The process steps are basically the same as those in Comparative Example 3, except that the recycled micro powder is replaced with lithium tailings, and the mass ratio of sieved shale, sludge, fly ash and lithium tailings is 5.5:1.5:1:2. The specific amounts are shown in Table 6.

[0078] Table 6 Raw material ratios for Comparative Examples 3-6

[0079] Ratio Shale (g) Sludge (g) Fly ash (g) Solidification agent (g) Total weight (g) Comparative Example 3 6∶1∶1∶2 12.002 2.004 2.005 Regenerated fine powder 4.003 20.013 Comparative Example 4 6.5∶1.5∶1∶1 13.001 3.003 2.003 Regenerated fine powder 2.002 20.010 Comparative Example 5 6∶2∶1∶1 12.001 4.003 2.002 Lithium mine tailings 2.002 20.007 Comparative Example 6 5.5∶1.5∶1∶2 11.001 3.002 2.003 Lithium mine tailings 4.003 20.008

[0080] The obtained brick samples were subjected to leaching experiments according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557-2010), and the leaching concentrations of the main heavy metals obtained are shown in Table 7.

[0081] Table 7 shows the leaching concentrations (ug / L) of the main heavy metals in the brick samples prepared in Comparative Examples 3-6.

[0082] Cr Ni Cu Zn As Cd Hg Pb Comparative Example 3 12588.0 4.0 7.0 272.0 43.0 2.0 29.0 103.0 Comparative Example 4 9555.0 10.0 42.0 297.0 10.0 1.0 42.0 18.0 Comparative Example 5 16543.0 5.0 21.0 430.0 2215.0 1.0 52.0 66.0 Comparative Example 6 25074.0 2.0 53.0 719.0 4302.0 1.0 15.0 43.0

[0083] Comparing the results in Tables 5, 6, and 7, it can be seen that when the curing agent is directly mixed with shale, sludge, and fly ash, the curing effect of heavy metals in the prepared brick samples is poor, and the leaching concentration of heavy metals increases significantly, especially Cr and As, failing to meet the heavy metal leaching concentration standards in the national standard GB 8978. Comparative Examples 3 and 4 may be due to insufficient activity of the recycled micropowder in the reaction, or excessive OH groups introduced by it. - The asphalt combines with Cr to form easily leached substances, and since no pretreatment of alkaline-activated hydrothermal reaction was performed, the solidification effect was insufficient. In contrast, the lithium tailings contain a high asphalt content, and Comparative Examples 5 and 6 could not effectively solidify asphalt without alkaline-activated hydrothermal reaction pretreatment.

[0084] The results above show that, compared with existing conventional methods, the co-treatment method of waste incineration fly ash and lithium ore tailings of this invention, using waste incineration fly ash and lithium ore tailings as raw materials, adopts a comprehensive treatment approach of "alkaline activation + hydrothermal pretreatment + sintering and solidification". It can utilize lithium ore tailings to slowly release heavy metals in fly ash matrix shale bricks, achieving the dual goals of waste-to-waste treatment, efficient solidification, and slow release of heavy metals. It has the advantages of simple steps, convenient operation, low cost, short cycle, good stabilization effect, environmental protection and energy saving. It can quickly prepare shale bricks from waste incineration fly ash and lithium ore tailings, which is of great significance for realizing the harmless treatment and resource utilization of waste incineration fly ash and lithium ore tailings.

[0085] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for co-treating fly ash from waste incineration and tailings from lithium mines, characterized in that: Includes the following steps: S1. Mix the fly ash from waste incineration with lithium tailings to obtain a mixture; S2. Mix the mixture with an alkaline activator and perform alkaline activation; S3. The mixture after alkali activation is subjected to hydrothermal reaction, and solid-liquid separation is performed to obtain pretreated liquid and pretreated residue. The pretreated residue is washed with water to obtain pretreated product. S4. Mix shale or coal gangue, sludge with the pretreated product, add water, and sinter to complete the co-treatment of waste incineration fly ash and lithium mine tailings.

2. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 1, characterized in that: In step S1, the lithium tailings contain Fe, Al, Si, and Ca, with the following mass percentages: Fe 1%–5%, Al 10%–30%, Si 55%–80%, and Ca 3%–10%.

3. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 2, characterized in that: In step S1, the mass ratio of the waste incineration fly ash to the lithium tailings is 5 to 15:

1.

4. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 3, characterized in that: In step S1, the mass ratio of the waste incineration fly ash to the lithium ore tailings is 7.7 to 12.5:

1.

5. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 4, characterized in that: In step S2, the solid-liquid ratio of the mixture to the alkaline activator is 1g:1 mL to 10 mL, and the concentration of the alkaline activator is 0.1mol / L to 1.0mol / L; the alkaline activator is a NaOH solution.

6. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 5, characterized in that: In step S3, the temperature of the hydrothermal reaction is 70℃~180℃, and the time of the hydrothermal reaction is 30min~60min.

7. The method for co-treating fly ash from waste incineration and lithium tailings according to any one of claims 1 to 6, characterized in that: In step S4, the mass ratio of shale or coal gangue, sludge and pretreatment product is 6-9:1-3:0.5-2.

8. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 7, characterized in that: In step S4, the sintering temperature is 700℃~1150℃, the sintering time is 0.5~1.5h, and the sintering heating rate is 3℃ / min~10℃ / min.

9. The method for co-treatment of waste incineration fly ash and lithium ore tailings according to claim 8, characterized in that: In step S1, the incineration fly ash and lithium tailings need to be crushed and / or ground and sieved before mixing. The particle size of the incineration fly ash and lithium tailings after sieving is ≤150μm.

10. The method for co-treatment of waste incineration fly ash and lithium mine tailings according to claim 9, characterized in that: In step S1, the incineration fly ash and lithium tailings are mixed by stirring, and the stirring speed is 50 r / min to 500 r / min, and the stirring time is 3 min to 10 min. In step S2, the alkaline activation involves mixing the mixture with an alkaline activator and then letting it stand for 3 to 20 minutes. In step S3, the pretreatment liquid is returned to the hydrothermal reaction of step S3 as a reaction medium, and the washing liquid generated by the water washing is returned to the hydrothermal reaction of step S3 as a reaction medium. In step S4, the amount of water added is 12% to 20% of the total mass of the solid raw materials.

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