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CN-121988593-A - Iron ore tailing slag restoration method based on plant planting

CN121988593ACN 121988593 ACN121988593 ACN 121988593ACN-121988593-A

Abstract

The invention provides a method for repairing iron ore tailing slag based on plant planting, and belongs to the technical field of tailing slag repairing. The invention can effectively passivate toxic substances by concentrating heavy metal chelating bacteria in a polluted core area, and can enhance plant metabolism activity by focusing growth promoting bacteria in a nutrient absorption area, and the mycorrhizal fungi can further expand a water transportation channel to form a repair unit with definite space division. The partition cooperation mode not only avoids the competition loss of the flora in the traditional mixed inoculation, but also integrates the physical blocking, chemical passivation and biological enrichment effects of heavy metals into a synergistic repair chain through the deep symbiosis of microorganisms and plants, and greatly shortens the migration and transformation period of pollutants.

Inventors

  • LIU JUNJIAN
  • SUN HUAN
  • LI XIANGQIAN
  • SHI JINGTAO
  • YANG WENHAO
  • LI LIYANG

Assignees

  • 中国地质调查局廊坊自然资源综合调查中心

Dates

Publication Date
20260508
Application Date
20260331

Claims (8)

  1. 1. The modification method of the iron ore tailing slag restoration method based on plant planting of the iron ore tailing slag is characterized by comprising the following steps of: (1) Screening plants with cadmium and zinc contents above 1000mg/kg and transport coefficient greater than 1.5, transpiration rate greater than 5mmol/s per square meter, and citric acid and oxalic acid contents greater than 50 mu mol/g secreted by root system, wherein the plants comprise herba Lespedezae Cuneatae, herba Medicaginis, poplar and amorpha fruticosa; (2) Carrying out three-stage domestication on the plants screened in the step S3 in a climatic chamber, wherein the initial stage is to cultivate for 15 days with the concentration of one fourth of the heavy metal background value of the mining area soil, the second stage is to cultivate for 20 days with the concentration of the heavy metal background value of the mining area soil, the daily average illumination intensity is maintained at 800-850 mu mol/S per square meter and the day-to-day temperature difference is maintained at 10-12 ℃, and the third stage is to adopt two times of the concentration of the heavy metal background value of the mining area soil, simulate the dry-wet alternation condition of the mining area, the daily irrigation amount is 10-30 mm, and the total domestication period is 60 days; (3) Respectively injecting arbuscular mycorrhizal fungi spore suspension with the concentration of 10 6 CFU/mL, burkholderia liquid with the concentration of 10 7 CFU/and fluorescent pseudomonas liquid with the concentration of 10 8 CFU/mL into a root tip area, a lateral root area and a root hair area of a plant, monitoring the pH value of the rhizosphere in real time, regulating the pH value to be 5.8-6.5, and controlling the conductivity threshold value to be less than 2.5ms/cm, wherein the colonization density of different bacterial groups on the root surface respectively reaches more than 10 4 、10 6 and 10 5 CFU/cm 2 ; (4) The method comprises the steps of paving a modified iron ore tailing slag matrix on the surface layer at the depth of 0-30cm, mixing and sowing leymus chinensis and alfalfa at the density of 20-25 plants/m 2 , implanting two-year poplar cutting seedlings at the middle layer of 30-100cm, planting the two-year poplar cutting seedlings at the plant spacing of 1.5 m, paving a root system water guide blanket with the thickness of 5mm and the water guide rate of 0.8L/h, arranging amorpha fruticosa seed balls with the diameter of 3cm on the bottom layer, each seed contains 0.5 g rhizobium inoculant, planting the 6 plants per square meter, burying ceramsite water guide pipes with the diameter of 10mm between the layers, and forming a cross-layer water circulation system with the capillary water rising rate of 2cm per day; (5) Monitoring the depth of layer at intervals of 30 cm, collecting the content of nitrate nitrogen, available phosphorus and quick-acting potassium every 2 hours, respectively setting the threshold value to 15-25 mg/kg, 8-12 mg/kg and 120-150 mg/kg, and then injecting EDTA chelated iron with the mass concentration of 0.05%, 0.02% zinc sulfate and 0.005% ammonium molybdate; (6) And pyrolyzing the plants enriched with the heavy metals by adopting a pyrolysis device to obtain the biochar containing the heavy metals.
  2. 2. The modification method of the plant-based iron ore tailing slag remediation method according to claim 1, wherein the preparation method of the modified iron ore tailing slag matrix of step (4) comprises the steps of: S1, crushing the grain diameter of the iron tailings to 0.5-10 mm, and separating ferromagnetic metal impurities by a permanent magnet drum magnetic separator with a magnetic field strength of 8000 gauss, wherein the slag is separated into fine grains, medium grains and coarse grains by a vibrating screen with a pore diameter of 2-8 mm; S2, mixing fine-grain, medium-grain and coarse-grain slag according to a mass ratio of 2-3:4-5:2-3 to form a mixed slag matrix; and S3, mixing a phosphate activator and wood fiber biochar according to the mass ratio of 1-2:3-5 to form a biochar mixture, then mixing the biochar mixture with the mixed slag matrix in the step S2, and adding a calcium-based mineral binder into the mixed slag matrix to obtain the modified iron ore tailing slag matrix.
  3. 3. The plant-based iron ore tailing slag remediation method according to claim 2, wherein the fine grain size in step S1 is 0.5-2 mm, the medium grain size is 2-5 mm, and the coarse grain size is >5mm.
  4. 4. The plant-based iron ore tailings restoration method according to claim 2, wherein the phosphate activator in step S3 is a mixture of monopotassium phosphate and disodium phosphate.
  5. 5. The plant-based iron ore tailing slag remediation method of claim 4, wherein the phosphate activator in step S3 is a mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate in a molar ratio of 1:2.
  6. 6. The plant-planting-based iron ore tailing slag remediation method according to claim 2, wherein the lignocellulosic biochar in step S3 is obtained by taking a biomass raw material rich in lignocellulose as a base material at a high temperature of 800 ℃ for 40 minutes in a nitrogen atmosphere, and the particle size of the lignocellulosic biochar is 0.15mm.
  7. 7. The plant-based iron ore tailings restoration method according to claim 2, wherein the calcium-based mineral binder in step S3 is a calcium-based bentonite binder, and the calcium-based mineral binder is added in an amount of 10-12wt% of the biochar mixture.
  8. 8. The plant-based iron ore tailing slag remediation method of claim 2, wherein the mass ratio of the calcium-based mineral binder to the biochar mixture in step S3 is 1:8-1:10.

Description

Iron ore tailing slag restoration method based on plant planting Technical Field The invention relates to the technical field of tailing slag restoration, in particular to a method for restoring iron ore tailing slag based on plant planting. Background The tailing slag repairing technology is characterized in that solid waste, namely tailing slag, generated in the iron ore dressing process is utilized and is converted into materials with engineering properties through specific process treatment, the materials are used for environmental repairing methods in the fields of road construction, land reclamation, mine reclamation and the like, and the problems of environmental pollution and resource waste caused by slag stacking can be effectively solved by adjusting the physicochemical properties of the slag. Slag remediation not only realizes the recycling of wastes, but also promotes ecological restoration and sustainable utilization of land resources, accords with the concepts of circular economy and green development, and provides important technical support for mine environment protection and treatment in China. However, static flora configuration in the prior art is difficult to adapt to dynamic change of physical and chemical properties of slag matrixes, fluctuation of plant survival rate is easy to occur, a single repair matrix cannot effectively integrate synergistic effects of physical barrier, chemical passivation and biological enrichment, a pollutant migration and transformation period is long, and meanwhile, dynamic regulation and control capability on rhizosphere microenvironment is lacking, so that soil structure improvement and ecological succession processes are slow, and synchronous optimization of pollution control and ecological reconstruction is difficult to realize. Disclosure of Invention In view of the above, the invention provides a plant-planting-based slag restoration method, which breaks through the limitation of a single restoration technology through the synergistic effect of microorganisms, plants and environments, and accelerates the transformation process of a slag site to a self-maintenance ecological system while realizing long-acting fixation of heavy metals. The modification method of the iron ore tailing slag restoration method based on plant planting comprises the following steps: (1) Screening plants with cadmium and zinc contents above 1000mg/kg and transport coefficient greater than 1.5, transpiration rate greater than 5mmol/s per square meter, and citric acid and oxalic acid contents greater than 50 mu mol/g secreted by root system, wherein the plants comprise herba Lespedezae Cuneatae, herba Medicaginis, poplar and amorpha fruticosa; (2) Carrying out three-stage domestication on the plants screened in the step S3 in a climatic chamber, wherein the initial stage is to cultivate for 15 days with the concentration of one fourth of the heavy metal background value of the mining area soil, the second stage is to cultivate for 20 days with the concentration of the heavy metal background value of the mining area soil, the daily average illumination intensity is maintained at 800-850 mu mol/S per square meter and the day-to-day temperature difference is maintained at 10-12 ℃, and the third stage is to adopt two times of the concentration of the heavy metal background value of the mining area soil, simulate the dry-wet alternation condition of the mining area, the daily irrigation amount is 10-30 mm, and the total domestication period is 60 days; (3) Respectively injecting arbuscular mycorrhizal fungi spore suspension with the concentration of 10 6 CFU/mL, burkholderia liquid with the concentration of 10 7 CFU/and fluorescent pseudomonas liquid with the concentration of 10 8 CFU/mL into a root tip area, a lateral root area and a root hair area of a plant, monitoring the pH value of the rhizosphere in real time, regulating the pH value to be 5.8-6.5, and controlling the conductivity threshold value to be less than 2.5ms/cm, wherein the colonization density of different bacterial groups on the root surface respectively reaches more than 10 4、106 and 10 5CFU/cm2; (4) The method comprises the steps of paving a modified iron ore tailing slag matrix on the surface layer at the depth of 0-30cm, mixing and sowing leymus chinensis and alfalfa at the density of 20-25 plants/m 2, implanting two-year poplar cutting seedlings at the middle layer of 30-100cm, planting the two-year poplar cutting seedlings at the plant spacing of 1.5 m, paving a root system water guide blanket with the thickness of 5mm and the water guide rate of 0.8L/h, arranging amorpha fruticosa seed balls with the diameter of 3cm on the bottom layer, each seed contains 0.5 g rhizobium inoculant, planting the 6 plants per square meter, burying ceramsite water guide pipes with the diameter of 10mm between the layers, and forming a cross-layer water circulation system with the capillary water rising rate of 2cm per day; (5)