A method for controlling and blocking pollution of beryllium and thallium in lithium slag-based artificial soil
By designing differentiated multi-level passivation schemes in lithium slag-based artificial soil and utilizing the spatial compatibility of modified biochar matrix with other materials, a multi-element synergistic passivation system was constructed. This solved the problems of poor passivation effect and poor long-term stability of beryllium and thallium in lithium slag-based artificial soil, achieving long-term stable passivation of beryllium and thallium and ensuring the safe use of artificial soil.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GANJIANG INNOVATION ACAD CHINESE ACAD OF SCI
- Filing Date
- 2026-05-09
- Publication Date
- 2026-06-09
AI Technical Summary
Existing technologies have poor passivation effects on beryllium and thallium in lithium slag-based artificial soil, and their long-term stability is poor. They are difficult to passivate beryllium and thallium simultaneously and efficiently, and there is a risk of secondary pollution.
A differentiated, multi-level passivation scheme was adopted, in which modified biochar matrix, struvite, humus, microbial agents, alkaline buffering materials and strongly alkaline solidification materials were applied to the ecological functional layer, buffer regulation layer and solidification and storage layer of lithium slag-based artificial soil to construct a multi-element synergistic passivation system.
Long-term stable passivation of beryllium and thallium has been achieved, with leaching concentrations below national environmental quality control standards, ensuring the safe utilization of artificial soil.
Smart Images
Figure CN122164737A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field, specifically relating to a method for controlling beryllium and thallium contamination in lithium slag-based artificial soil. Background Technology
[0002] The lithium extraction process from lithium ore generates a large amount of solid waste, such as lithium slag. Mixing this waste with natural soil and amendments to prepare "artificial soil" can be used for soil remediation in mining areas and slope greening, offering advantages such as large capacity, pollution reduction and carbon sequestration, and large-scale production. However, lithium slag often contains high concentrations of toxic metals such as beryllium and thallium, which have extremely high mobility and biotoxicity in the environment. Direct utilization without treatment poses serious environmental and health risks.
[0003] Currently, the existing passivation technologies for heavy metal contaminated soil mainly include: (1) applying inorganic passivating agents such as lime, phosphate, and clay minerals to reduce the activity of heavy metals by increasing pH, co-precipitation, or adsorption; (2) applying organic passivating agents such as biochar and organic fertilizer to fix heavy metals through adsorption and complexation; and (3) microbial remediation technology to utilize microbial metabolic activities to transform heavy metal forms. However, these technologies have certain shortcomings when applied to lithium slag-based artificial soil: universal single treatment: usually the same passivating agent is used for the entire soil layer, ignoring the functional stratification and structural differences formed by artificial soil in the process of simulating natural soil formation, resulting in low remediation efficiency or the existence of a "short-board effect". The specific passivation effect on beryllium and thallium is not good: beryllium has very unique properties in acid and alkali environments, and it exhibits obvious amphoteric characteristics; while thallium may still exist in a monovalent form (Tl) in neutral to alkaline environments. + Thallium exists and has strong migration properties. Conventional passivating agents (such as lime alone) have unstable fixation effects on thallium and are difficult to simultaneously and efficiently passivate beryllium and thallium. It also exhibits poor long-term stability: under environmental changes such as alternating wet and dry conditions and leaching by acidic precipitation, passivated heavy metals may be reactivated, leading to the risk of secondary pollution.
[0004] Therefore, developing a differentiated control method for simultaneously, efficiently, and stably passivating beryllium and thallium based on the profile characteristics of lithium slag-based artificial soil has become crucial for promoting the safe and resource-based utilization of this solid waste. Summary of the Invention
[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for controlling beryllium and thallium contamination in lithium slag-based artificial soil.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a method for controlling beryllium and thallium contamination in lithium slag-based artificial soil, wherein the method involves hierarchical remediation of the lithium slag-based artificial soil, comprising the following steps:
[0008] The first composite passivating agent, the second composite passivating agent, and the third composite passivating agent were applied to the ecological functional layer, the buffer regulation layer, and the solidification and storage layer of the lithium slag-based artificial soil, respectively, for repair.
[0009] The first composite passivating agent includes a modified biochar matrix, struvite, humus, and microbial inoculants.
[0010] The second composite passivating agent includes a modified biochar matrix and an alkaline buffer material;
[0011] The third composite passivating agent includes a modified biochar matrix and a strongly alkaline curing material.
[0012] This invention designs a differentiated, multi-level passivation scheme based on the different functions of each soil layer in artificial soil, achieving precise remediation. Using modified biochar as the core matrix, it coordinates struvite, steel slag, dolomite, lime, humus, and functional microorganisms in spatially integrated according to specific functional layers to construct a multi-element synergistic passivation system targeting beryllium and thallium. This ensures that, after barrier control, the leaching concentrations of beryllium and thallium in each soil layer remain consistently below the relevant national environmental quality control standards, systematically addressing the potential risk of vertical migration of beryllium and thallium contaminants in lithium slag-based artificial soil and guaranteeing the safe utilization of artificial soil.
[0013] Preferably, the modified biochar matrix is a modified biochar matrix with beryllium and thallium adsorption and complexation functions.
[0014] Preferably, the modified biochar matrix is magnesium-modified biochar.
[0015] The magnesium modification treatment aims to increase the specific surface area of biochar and enhance its ion exchange, complexation, and precipitation capabilities for heavy metal cations such as beryllium and thallium. The preparation method can refer to conventional preparation methods in the art (exemplarily CN116282326A). However, it should be noted that the core of this invention is not the modified biochar matrix itself, but rather the spatial compatibility of such modified biochar matrix with materials such as struvite, calcite carbide slag, and functional microorganisms according to specific functional layers, in order to systematically solve the potential risk of vertical migration of beryllium and thallium contaminating metals in lithium slag-based artificial soil.
[0016] The struvite is a conventional magnesium ammonium phosphate salt in the art, which can be obtained commercially or prepared by conventional precipitation reaction. Its main function is to provide phosphate ions to form phosphate precipitates with beryllium and thallium ions.
[0017] Preferably, the humus is any one or a combination of at least two of peat soil, weathered coal humic acid, or fully decomposed compost organic matter.
[0018] Preferably, the total organic carbon content in the humus is not less than 30%, for example, it can be 30%, 31%, 33%, 35%, 38%, 40%, 45%, 48%, etc.
[0019] Preferably, the strains in the microbial agent are microbial species with beryllium and / or thallium resistance.
[0020] Preferably, the alkaline buffer material is selected from any one or a combination of at least two of calcite, dolomite, or steel slag.
[0021] Preferably, the calcite has a particle size of not less than 100 mesh.
[0022] Preferably, the dolomite has a particle size of not less than 100 mesh.
[0023] Preferably, the calcium oxide content in the steel slag is not higher than 1%.
[0024] Preferably, the strongly alkaline curing material is selected from lime and / or carbide slag.
[0025] Preferably, the first composite passivating agent comprises, by weight, 60-70 parts of modified biochar matrix, 20-25 parts of struvite, 20-35 parts of humus, and 0.5-1 parts of microbial inoculant.
[0026] Among them, the aforementioned "60-70 portions" can be, for example, 60 portions, 61 portions, 62 portions, 63 portions, 64 portions, 65 portions, 66 portions, 67 portions, 68 portions, 69 portions, 70 portions, etc.
[0027] The aforementioned "20-25 portions" could be, for example, 20 portions, 21 portions, 22 portions, 23 portions, 24 portions, 25 portions, etc.
[0028] The "0.5-1 part" mentioned above can be, for example, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc.
[0029] In the first composite passivating agent of this invention, based on the synergistic relationship between the modified biochar matrix, struvite, humus and microbial inoculant, it was further found that when the dosage ratio of the four components is within the above-mentioned specific range, it has a better treatment and restoration effect on the ecological functional layer of lithium slag-based artificial soil.
[0030] The second composite passivating agent comprises, by weight, 50-60 parts of modified biochar matrix and 30-40 parts of alkaline buffer material.
[0031] Among them, the above "50-60 portions" can be, for example, 50 portions, 51 portions, 52 portions, 53 portions, 54 portions, 55 portions, 56 portions, 57 portions, 58 portions, 59 portions, 60 portions, etc.
[0032] The aforementioned "30-40 portions" could be, for example, 30 portions, 31 portions, 32 portions, 33 portions, 34 portions, 35 portions, 36 portions, 37 portions, 38 portions, 39 portions, 40 portions, etc.
[0033] In the second composite passivating agent of this invention, based on the synergistic relationship between the modified biochar matrix and the alkaline buffer material, it was further found that when the ratio of the two is within the above-mentioned specific range, it has a better treatment and repair effect on the buffer regulation layer of lithium slag-based artificial soil.
[0034] The third composite passivating agent comprises, by weight, 50-60 parts of modified biochar matrix and 40-50 parts of strongly alkaline curing material.
[0035] Among them, the above "50-60 portions" can be, for example, 50 portions, 51 portions, 52 portions, 53 portions, 54 portions, 55 portions, 56 portions, 57 portions, 58 portions, 59 portions, 60 portions, etc.
[0036] The aforementioned "40-50 portions" could be, for example, 40 portions, 41 portions, 42 portions, 43 portions, 44 portions, 45 portions, 46 portions, 47 portions, 48 portions, 49 portions, 50 portions, etc.
[0037] In the third composite passivating agent described in this invention, based on the synergistic relationship between the modified biochar matrix and the strongly alkaline solidification material, it was further discovered that when the ratio of the two is within the above-mentioned specific range, it has a better treatment and repair effect on the solidification and sealing layer of lithium slag-based artificial soil.
[0038] Preferably, the concentration of viable bacteria in the microbial agent is not less than 1×10⁻⁶. 8 CFU / mL or 1×10 8 CFU / g, for example, could be 1×10 8 CFU / mL or 1×10 8 CFU / g, for example 1×10 8 CFU / mL (CFU / g), 2×10 8 CFU / mL (CFU / g), 5×10 8 CFU / mL (CFU / g), 8×10 8 CFU / mL (CFU / g), 1×10 9 CFU / mL (CFU / g), 5×10 10 CFU / mL (CFU / g), 1×10 11 CFU / mL (CFU / g), etc. Other specific point values within this range can be selected, which will not be elaborated here.
[0039] Preferably, the concentration of viable bacteria in the microbial agent is not less than 5 × 10⁻⁶. 8 CFU / mL or 5×10 8 CFU / g.
[0040] Preferably, the application amounts of the first composite passivating agent, the second composite passivating agent, and the third composite passivating agent are each independently 0.5%-2% of the dry weight of the ecological functional layer, the buffer regulation layer, and the solidification and sealing layer of the lithium slag-based artificial soil. For example, they can be 0.5%, 1%, 1.5%, 1.8%, 2%, etc. Other specific values within this range can be selected, and will not be elaborated here.
[0041] The composite passivating agent, when used in a specific dosage, provides superior repair effects on lithium slag-based artificial soil.
[0042] Preferably, the repair time is not less than 14 days.
[0043] Compared with the prior art, the present invention has the following beneficial effects:
[0044] This invention designs a differentiated, multi-level passivation scheme based on the different functions of each soil layer in artificial soil, achieving precise remediation. Using modified biochar as the core matrix, it coordinates struvite, steel slag, dolomite, lime, humus, and functional microorganisms in spatially integrated according to specific functional layers to construct a multi-element synergistic passivation system targeting beryllium and thallium. This ensures that, after barrier control, the leaching concentrations of beryllium and thallium in each soil layer remain consistently below the relevant national environmental quality control standards, systematically addressing the potential risk of vertical migration of beryllium and thallium contaminants in lithium slag-based artificial soil and guaranteeing the safe utilization of artificial soil. Attached Figure Description
[0045] Figure 1 This is a schematic diagram of the layered structure of lithium slag-based artificial soil profile and simulated acid rain leaching.
[0046] Figure 2 This is a graph showing the statistical results of beryllium concentration in the leachate of each group of leaching columns under continuous acid rain leaching.
[0047] Figure 3 This is a graph showing the statistical results of thallium concentration in the leachate of each group of leaching columns under continuous acid rain leaching. Detailed Implementation
[0048] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0049] The LBAJ-100 strain mentioned below is classified as Burkholderia gladioli LBAJ-100, deposited at the China Center for Type Culture Collection (CCTCC) with accession number CCTCC NO: M 20251345, deposited on June 12, 2025, and located at Wuhan University, Wuhan, China.
[0050] The magnesium-modified biochar mentioned below was prepared according to the method in CN116282326A.
[0051] The struvite mentioned below was prepared by the following method: magnesium salt, phosphate and ammonium salt were dissolved in water at a magnesium, phosphorus and nitrogen molar ratio of 1.2:1:1.2. The pH was adjusted to 9.0±0.2 with alkaline solution under stirring. After reacting for 30 min, the mixture was allowed to stand for 1 h, filtered, washed and dried at 40-50℃ to constant weight to obtain struvite.
[0052] The lithium slag-based artificial soil (untreated) mentioned below comes from the Nanjing Institute of Soil Science, Chinese Academy of Sciences.
[0053] The calcium carbide slag mentioned below refers to the waste residue generated during the acetylene generation process in the calcium carbide-based polyvinyl chloride (PVC) production process after drying, crushing, and sieving.
[0054] The humus mentioned below is a compost product obtained by fermenting coal gangue and soybean straw (mass ratio 1.5:8.5) at 60°C for 24 days until fully decomposed using thermophilic lignin-degrading bacteria (obtained in the laboratory by isolating and enriching lignin as the sole carbon source).
[0055] Example 1
[0056] This embodiment demonstrates a repair test on lithium slag-based artificial soil.
[0057] (1) Grouping:
[0058] Group T1: Weigh out 1.5% of the dry weight of lithium slag-based artificial soil (untreated). Mix it evenly with the corresponding soil layers (ecological function layer, buffer regulation layer, and solidification and storage layer) of the lithium slag-based artificial soil, and then fill it into the leaching column from top to bottom.
[0059] Group T2: Application of control agents for each soil layer in lithium slag-based artificial soil: Ecological functional layer (0.5% struvite + 1% magnesium-modified biochar); Buffer and regulation layer (0.5% steel slag + 1% magnesium-modified biochar); Solidification and sealing layer (0.5% lime + 1% magnesium-modified biochar). After each layer is evenly mixed, it is filled from top to bottom into the leaching column.
[0060] Group T3: Application of control agents for each soil layer in lithium slag-based artificial soil: Ecological functional layer (0.25% struvite + 0.25% humus + 1% magnesium-modified biochar); Buffer and regulation layer (0.5% dolomite + 1% magnesium-modified biochar); Solidification and sealing layer (0.5% lime + 1% magnesium-modified biochar). After each layer is evenly mixed, it is filled from top to bottom into the leaching column.
[0061] Group T4: Application of control agents for each soil layer in lithium slag-based artificial soil: Ecological functional layer (0.25% struvite + 0.25% humus + 1% magnesium-modified biochar); Buffer and regulation layer (0.25% calcite + 0.25% steel slag + 1% magnesium-modified biochar); Solidification and sealing layer (0.25% lime + 0.25% carbide slag + 1% magnesium-modified biochar). After each layer is uniformly mixed, it is filled from top to bottom into the leaching column.
[0062] Group T5: Application of soil inhibitors in corresponding soil layers of lithium slag-based artificial soil: Ecological functional layer (0.25% struvite + 0.25% humus + 5×10 8 The mixture consists of: LBAJ-100 strain (CFU / g soil) + 1% magnesium-modified biochar; a buffer control layer (0.25% dolomite + 0.25% steel slag + 1% magnesium-modified biochar); and a solidification and sealing layer (0.25% lime + 0.25% carbide slag + 1% magnesium-modified biochar). After each layer is uniformly mixed, it is filled from top to bottom into the leaching column.
[0063] (2) Acid rain leaching:
[0064] Artificial acid rain at pH 4.5 was used to continuously leach each column from top to bottom at a constant flow rate of 0.3 mL / min. A control group (CK) was prepared by layering lithium slag-based artificial soil without any added components and subjected to the same artificial acid rain leaching test. The leaching experiment lasted for 30 days, and the leachate from the bottom of the column was collected periodically. The concentrations of beryllium (Be) and thallium (Tl) in the leachate at each time point were determined using inductively coupled plasma mass spectrometry (ICP-MS). The layered structure of the lithium slag-based artificial soil profile and the schematic diagram of simulated acid rain leaching are shown in the figure. Figure 1 As shown, the test results for each group are as follows: Figure 2 and Figure 3 As shown.
[0065] The results showed that
[0066] a) During the entire 30-day leaching cycle, the beryllium leaching concentration in the CK group fluctuated, with an average leaching concentration of approximately 0.15 ppb; the thallium leaching concentration was high in the early stage, and although it decreased thereafter, it remained relatively stable throughout the cycle.
[0067] b) The modified biochar in group T1 exhibited good adsorption and fixation capacity for beryllium, effectively reducing its leaching concentration. It also showed significant fixation effect on thallium, maintaining the thallium concentration in the leachate at a low level.
[0068] c) After leaching began in group T2, the leaching concentration of beryllium rapidly decreased to an extremely low level. Within 30 days, the overall leaching concentration remained stable between 0 and 0.04 μg / L, significantly lower than the control group (CK) and far below the limit of the Integrated Wastewater Discharge Standard. From the first day of leaching, the concentration of thallium in the leachate remained stable below 5 μg / L and showed a gradual decreasing trend during the 30-day leaching period, with the control effect continuously enhanced.
[0069] d) In group T3, beryllium was effectively suppressed to an extremely low concentration range (0-0.04 ppb); the leaching control of thallium was better and faster than that of group T1, reaching a lower concentration plateau in the early stage of leaching and maintaining a downward trend throughout the cycle, showing stronger long-term fixation potential.
[0070] e) In group T4, the leaching of beryllium and thallium was significantly inhibited, and the leaching concentration decreased significantly and remained stable throughout the leaching cycle.
[0071] f) Group T5 showed better control over beryllium and thallium than Group T4, exhibiting lower and more stable leaching concentrations throughout the 30-day leaching period.
[0072] In summary, this invention designs a differentiated, multi-level passivation scheme based on the different functions of each soil layer in the artificial soil, achieving precise remediation. Using modified biochar matrix as the core matrix, it coordinates struvite, steel slag, dolomite, lime, humus, and functional microorganisms according to specific functional layers, constructing a multi-element synergistic passivation system targeting beryllium and thallium. This ensures that after barrier control, the leaching concentrations of beryllium and thallium in each soil layer remain consistently below the relevant national environmental quality control standards, systematically addressing the potential risk of vertical migration of beryllium and thallium contaminants in lithium slag-based artificial soils and guaranteeing the safe utilization of the artificial soil.
[0073] The applicant declares that the technical solution of this invention is illustrated by the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.
[0074] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0075] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
Claims
1. A method for controlling beryllium and thallium contamination in lithium slag-based artificial soil, characterized in that, The aforementioned control method involves layered remediation of lithium slag-based artificial soil, including the following steps: The first composite passivating agent, the second composite passivating agent, and the third composite passivating agent were applied to the ecological functional layer, the buffer regulation layer, and the solidification and storage layer of the lithium slag-based artificial soil, respectively, for repair. The first composite passivating agent includes a modified biochar matrix, struvite, humus, and microbial inoculants. The second composite passivating agent includes a modified biochar matrix and an alkaline buffer material; The third composite passivating agent includes a modified biochar matrix and a strongly alkaline curing material.
2. The resistance control method according to claim 1, characterized in that, The modified biochar matrix is a modified biochar matrix with beryllium and thallium adsorption and complexation functions.
3. The resistance control method according to claim 1, characterized in that, The strains in the microbial agent are microbial species with beryllium and / or thallium resistance.
4. The resistance control method according to claim 1, characterized in that, The alkaline buffer material is selected from any one or a combination of at least two of calcite, dolomite, or steel slag.
5. The resistance control method according to claim 1, characterized in that, The strongly alkaline curing material is selected from lime and / or carbide slag.
6. The resistance control method according to claim 1, characterized in that, The first composite passivating agent comprises, by mass parts, 60-70 parts of modified biochar matrix, 20-25 parts of struvite, 20-35 parts of humus, and 0.5-1 parts of microbial inoculant; The second composite passivating agent comprises, by weight, 50-60 parts of modified biochar matrix and 30-40 parts of alkaline buffer material; The third composite passivating agent comprises, by weight, 50-60 parts of modified biochar matrix and 40-50 parts of strongly alkaline curing material.
7. The resistance control method according to claim 1, characterized in that, The concentration of viable bacteria in the microbial agent is not less than 1×10⁻⁶. 8 CFU / mL or 1×10 8 CFU / g.
8. The resistance control method according to claim 7, characterized in that, The concentration of viable bacteria in the microbial agent is not less than 5 × 10⁻⁶. 8 CFU / mL or 5×10 8 CFU / g.
9. The resistance control method according to claim 1, characterized in that, The application amounts of the first composite passivating agent, the second composite passivating agent, and the third composite passivating agent are each 0.5%-2% of the dry weight of the ecological functional layer, buffer regulation layer, and solidification and sealing layer soil of the lithium slag-based artificial soil.
10. The resistance control method according to claim 1, characterized in that, The repair time shall not be less than 14 days.