Method for modifying biomass to strengthen ion adsorption type rare earth ore bioleaching

Abstract

The present application belongs to the field of hydrometallurgy, and relates to a method for modifying biomass to strengthen bioleaching of ion-adsorbed rare earth ore, which is carried out according to the following steps: modifying biomass with a sulfuric acid solution with a mass concentration of 40% to 80% to obtain a modified biomass solution; mixing the modified biomass solution with Czapek's liquid medium to obtain a mixed culture solution; inoculating the mixed culture solution with mixed microbial strains to obtain a fermentation solution; mixing the fermentation solution with ion-adsorbed rare earth ore, stirring, filtering, and obtaining the supernatant as a rare earth leaching solution. The present application uses the modified biomass solution to provide a nutrient medium and a fermentation substrate for microorganisms, improves the activity of the microorganisms and the yield of organic acids, and has the characteristics of low cost, wide raw material sources, and small environmental pollution.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgy, and specifically relates to a method for bioleaching of rare earth minerals using modified biomass-enhanced ion adsorption. Background Technology

[0002] Based on the principle of cation exchange, ion adsorption-based rare earth mining has mainly gone through three stages: first-generation sodium chloride pond leaching, second-generation ammonium sulfate heap leaching, and third-generation ammonium sulfate in-situ leaching. Ammonium sulfate migrates and diffuses in the soil, surface water, and groundwater of the mining area through seepage and surface runoff, leading to severe regional ammonia nitrogen pollution. Therefore, from the perspective of addressing soil calcium-magnesium imbalance, reducing impurity leaching, and improving leaching efficiency, new-generation ammonium-free leaching agents such as magnesium sulfate and aluminum sulfate have been proposed and are gradually being applied. However, they still pose a risk of sulfate pollution. Novel leaching agents, such as composite leaching agents, organic leaching agents, plant leaching agents, surfactants, and bioleaching agents, are constantly being proposed.

[0003] Bioleaching, also known as biohydrometallurgy, is a technique that utilizes the interaction between microorganisms or their metabolites and target materials to separate and extract certain insoluble components (such as metals) from the solid phase. It boasts advantages such as low cost, mild conditions, environmental friendliness, simple operation, and wide adaptability, making it one of the methods for treating low-grade ores, solid waste, and refractory materials. Due to the significant role of microorganisms in rare earth migration and leaching, it is considered a promising alternative to ion-adsorption-based rare earth extraction. A 2018 study used Aspergillus sp. and Bacillus sp. for 60 days of bioleaching of ion-adsorption-based rare earths. The results showed that the release of heavy rare earth elements was similar between salt leaching and Aspergillus leaching (73.1% and 70.7%, respectively), with an increased ratio of heavy to light rare earth elements. pH value was negatively correlated with rare earth element release, indicating that the acid produced by microorganisms facilitated rare earth leaching. This study demonstrates the potential for bioleaching rare earth elements from ion-adsorption-based rare earths. Patent application CN202110254841.5 discloses a composite microbial agent for leaching weathered crust leached rare earth ores and its preparation method, further illustrating the feasibility of bioleaching. However, existing microbial leaching methods still suffer from low leaching efficiency. Summary of the Invention

[0004] Based on the problems existing in the prior art, the present invention provides a method for bioleaching of rare earth minerals by modified biomass enhanced ion adsorption. The method utilizes the organic components in the modified biomass liquid as a nutrient substrate and fermentation substrate for microorganisms, thereby improving microbial activity and organic acid yield, and thus improving bioleaching efficiency.

[0005] The specific technical solution provided by this invention is as follows:

[0006] This invention provides a method for bioleaching of rare earth minerals using modified biomass-enhanced ion adsorption, comprising the following steps:

[0007] Biomass is modified using a sulfuric acid solution with a mass concentration of 40% to 80% to obtain a biomass modified solution. If the concentration of the sulfuric acid solution is too low, the modification purpose will not be achieved, while if the concentration is too high, it will be dangerous and waste reagents.

[0008] The biomass-modified liquid was mixed with Czapek's liquid culture medium to obtain a mixed culture medium;

[0009] A mixed microbial strain is inoculated into the mixed culture medium to obtain a fermentation broth; the microbial strain is one or more of the following: Aspergillus niger and Aspergillus flavus, Aspergillus rouxii, Smutella cornensis, Omexozoon yeast, Malassezia, Trichoderma reesei, Cladosporium, Alternaria alternata, and Fusarium tumefaciens.

[0010] The fermentation broth is mixed with ion-adsorption type rare earth ore, stirred, filtered, and the resulting supernatant is the rare earth leachate.

[0011] In a preferred embodiment of the present invention, the ratio of the sulfuric acid solution to the biomass is 5 mL to 10 mL: 1 g.

[0012] In a preferred embodiment of the present invention, the modification involves mixing sulfuric acid solution with biomass and stirring at 60°C to 80°C and 200 rpm to 400 rpm for 1 to 2 hours.

[0013] In a preferred embodiment of the present invention, the volume ratio of the biomass modified liquid to the Czapek liquid culture medium is 0.1 to 0.3:1.

[0014] In a preferred embodiment of the present invention, 5% to 15% of microbial strains are inoculated into the mixed culture medium based on the total volume of the mixed culture medium, wherein the effective viable count of the microbial strains is 0.5 × 10⁻⁶. 9 Cells / mL ~ 5×10 9 per mL.

[0015] In a preferred embodiment of the present invention, after inoculating with microbial strains, fermentation is carried out at a temperature of 20℃~35℃ and a stirring speed of 200rpm~400rpm for 24h~72h to obtain fermentation broth.

[0016] In a preferred embodiment of the present invention, the mixing ratio of the fermentation broth to the ion-adsorption type rare earth ore is 2 mL to 4 mL: 1 g.

[0017] In a preferred embodiment of the present invention, the fermentation broth is mixed with ion-adsorption type rare earth ore and stirred for 20 min to 80 min at a speed of 200 rpm to 400 rpm and a temperature of 20℃ to 50℃. After filtration, the supernatant obtained is a rare earth leachate.

[0018] In a preferred embodiment of the present invention, the biomass includes, but is not limited to, straw, rice husks, fruit shells, sugarcane bagasse, plant debris, weeds, fallen leaves, vines, branches, and other waste. Agricultural waste biomass is crushed and finely ground for 5-10 minutes to ensure a particle size of less than 200 μm, resulting in powdered biomass, which is then subjected to modification treatment.

[0019] As a preferred embodiment of the present invention, the Czapek liquid culture medium is formulated as follows: 3.0 g / L sodium nitrate, 1.0 g / L dipotassium hydrogen phosphate, 0.5 g / L magnesium sulfate, 0.5 g / L potassium chloride, 0.01 g / L ferrous sulfate, and 30.0 g / L sucrose.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1) Agricultural waste biomass can be modified into a nutrient substrate that can be utilized by microorganisms in a short time under the action of sulfuric acid, thereby improving the activity of microorganisms. On the other hand, agricultural waste biomass can be used as a fermentation substrate to be converted into rare earth element leaching agents such as citric acid, thereby improving the leaching efficiency of rare earth elements.

[0022] 2) The method provided by this invention has a wide range of raw material sources, low cost, minimal environmental pollution, and is clean, which is in line with the sustainable development policy and has good application prospects.

[0023] 3) The microbial strains required for the method provided by this invention are widely found in nature, and most of them are engineered strains for the food industry, which are environmentally friendly, safe and easy to obtain.

[0024] 4) The method provided by this invention can improve the bioleaching efficiency of ion-adsorption type rare earth minerals: under optimized conditions, the rare earth leaching rate is greater than 95%, an increase of about 10%.

[0025] 5) The method provided by this invention requires simple equipment, requires low investment, is easy to operate, and is easy to apply in industrial applications. Detailed Implementation

[0026] To make the method of the present invention easier to understand, the present invention will now be illustrated with specific embodiments. The specific embodiments described are for illustrative purposes only and are not intended to limit the present invention.

[0027] This invention provides a method for bioleaching of rare earth minerals using modified biomass-enhanced ion adsorption, comprising the following steps:

[0028] Biomass is modified with a sulfuric acid solution of 40%–80% by mass to obtain a biomass modified solution;

[0029] The biomass-modified liquid is mixed with Czapek's liquid medium to obtain a mixed culture medium; a mixed microbial strain is inoculated into the mixed culture medium to obtain a fermentation broth; the microbial strain is one or more of the following: Aspergillus niger and Aspergillus flavus, Rhus niger, corn smut, Omega yeast, Malassezia, Trichoderma reesei, Cladosporium, Alternaria alternata, and Fusarium oxysporum.

[0030] The fermentation broth is mixed with ion-adsorption type rare earth ore, stirred, filtered, and the resulting supernatant is the rare earth leachate.

[0031] This invention utilizes sulfuric acid to modify biomass in a short time. The modified biomass can be used as a nutrient for microorganisms, improving their activity. At the same time, it can also be used as a fermentation substrate to produce rare earth element extraction agents such as citric acid during subsequent fermentation, which can increase the rare earth leaching rate to more than 95%, which is about 10% higher than existing methods.

[0032] The method provided by this invention has minimal environmental pollution, uses inexpensive and readily available raw materials, is simple to operate, and is easy to industrialize.

[0033] The formula of Czapek's liquid culture medium used in this invention is: 3.0 g / L sodium nitrate, 1.0 g / L dipotassium hydrogen phosphate, 0.5 g / L magnesium sulfate, 0.5 g / L potassium chloride, 0.01 g / L ferrous sulfate, and 30.0 g / L sucrose.

[0034] In this embodiment of the invention, the rare earth element grade of the ion-adsorption type rare earth ore is 0.0335%.

[0035] In this embodiment of the invention, the agricultural waste biomass is wheat straw, with a particle size ≤200μm after fine grinding. Alternatively, one or a mixture of several of the following can be selected: straw, rice husks, fruit shells, sugarcane bagasse, plant debris, weeds, fallen leaves, vines, and branches.

[0036] All microbial strains used in this invention were purchased, and their preservation numbers are as follows: Aspergillus niger (CICC 40395), Aspergillus flavus (CICC 2121), Zygosaccharomyces rouxii (CICC 1379), Omnatifida yeast (CICC32993), Ustilago maydis (CGMCC 5.209), Malassezia (CICC 33081), Trichoderma reesei (CICC 2626), Cladosporium (CICC 2529), Alternaria alternata (CICC 40259), and Fusarium oxysporum (CICC 2489).

[0037] The concentrations of the microbial strains used were as follows: Aspergillus niger (1.23 × 10⁻⁶) 9(cFU / mL), Aspergillus flavus (1.20 × 10⁻⁶) 9 (cFU / mL), *Lactobacillus rhubarb* (1.04 × 10⁻⁶ cells / mL) 9 (1.09 × 10⁻⁶ cells / mL), Corn smut (1.09 × 10⁻⁶ cells / mL) 9 Omega yeast (0.99×10⁻⁶ cells / mL), Omega yeast (0.99×10⁻⁶ cells / mL) 9 (0.83 × 10⁻⁶ cells / mL), Malassezia (0.83 × 10⁻⁶ cells / mL) 9 Trichoderma reesei (0.96 × 10⁻⁶ cells / mL), Trichoderma reesei (0.96 × 10⁻⁶ cells / mL) 9 (crystals / mL), Cladosporium (1.01×10⁻⁶) 9 Alternaria (0.85 × 10⁻⁶ cells / mL), Alternaria (0.85 × 10⁻⁶ cells / mL) 9 (0.88 × 10⁻⁶ cells / mL), Fusarium oxysporum (0.88 × 10⁻⁶ cells / mL) 9 (units / mL).

[0038] Example 1

[0039] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial strain, a mixture of Aspergillus niger, Aspergillus flavus, Zygosacchariformis roux, and Omnikol yeast, was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 95.30%.

[0040] Example 2

[0041] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 40% sulfuric acid solution at a volume ratio of 10mL:1g and stirred at 80℃ and 300rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% Aspergillus niger was inoculated into the mixed culture solution, and fermentation was carried out at 30℃ and 300rpm for 48 hours to obtain a fermentation broth. 300mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4mL:1g to obtain a mixed slurry. The mixed slurry was stirred at 300rpm and 30℃ for 60 minutes, and then filtered to obtain the supernatant, which was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 95.64%.

[0042] Example 3

[0043] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with an 80% sulfuric acid solution at a volume ratio of 5 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% *Alternaria* was inoculated into the mixed culture solution, and fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes, and then filtered to obtain the supernatant, which was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 96.11%.

[0044] Example 4

[0045] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 60℃ and 400 rpm for 2 hours. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial inoculum composed of equal proportions of Aspergillus niger and Cladosporium was inoculated into the mixed culture solution and fermented at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes and filtered to obtain the supernatant, which is the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 96.72%.

[0046] Example 5

[0047] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 200 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial strain, a mixture of Aspergillus niger, Omnaeida yeast, and Malassezia, was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 95.60%.

[0048] Example 6

[0049] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.3:1 to obtain a mixed culture solution. 10% of a microbial inoculum, composed of equal proportions of Aspergillus niger, Fusarium oxysporum, Ustilago maydis, and Trichoderma reesei, was inoculated into the mixed culture solution and fermented at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes and filtered to obtain the supernatant, which is the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 96.59%.

[0050] Example 7

[0051] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.1:1 to obtain a mixed culture solution. 10% of a microbial strain, composed of equal proportions of Aspergillus niger, Aspergillus flavus, Ustilago maydis, Omega oryzae, and Malassezia, was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth mineral at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30°C for 60 minutes. The slurry was then filtered, and the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, revealing a rare earth leaching rate of 95.81%.

[0052] Example 8

[0053] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 5% of a microbial strain, a mixture of Aspergillus niger, Alternaria alternata, and Zygomyces rouxii, was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 96.43%.

[0054] Example 9

[0055] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified liquid was obtained. The biomass-modified liquid was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 15% of a microbial strain, composed of equal proportions of *Aspergillus niger*, *Zygosacchariformis*, *Cladosporium*, *Omega oryzae*, *Cladosporium*, and *Fusarium oxysporum*, was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth mineral at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30°C for 60 minutes. The slurry was then filtered, and the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, revealing a rare earth leaching rate of 96.08%.

[0056] Example 10

[0057] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial inoculum, composed of equal proportions of Aspergillus niger, Ustilago maydis, Alternaria alternata, and Trichoderma reesei, was inoculated into the mixed culture solution and fermented at 20℃ and 400 rpm for 72 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes and filtered to obtain the supernatant, which is the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 97.22%.

[0058] Example 11

[0059] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial strain, composed of an equal proportion of Aspergillus niger, Omega yeast, and Trichoderma reesei, was inoculated into the mixed culture solution and fermented at 35℃ and 400 rpm for 24 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes and filtered to obtain the supernatant, which is the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 95.75%.

[0060] Example 12

[0061] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial inoculum (a mixture of Aspergillus niger, Aspergillus flavus, Zygosacchariformis rouxae, and Omega yeast) was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 300 rpm and 30℃ for 60 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 95.14%.

[0062] Example 13

[0063] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial inoculum (a mixture of Aspergillus niger, Aspergillus flavus, Zygosacchariformis rouxae, and Omnikol yeast) was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 2 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 200 rpm and 50℃ for 80 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 96.44%.

[0064] Example 14

[0065] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial inoculum (a mixture of Aspergillus niger, Aspergillus flavus, Zygosacchariformis rouxae, and Omega yeast) was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 3 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 200 rpm and 50℃ for 80 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 97.17%.

[0066] Example 15

[0067] Wheat straw was crushed and finely ground for 10 minutes to obtain powdered biomass with a particle size ≤200μm. The powdered biomass was mixed with a 60% sulfuric acid solution at a volume ratio of 8 mL:1 g and stirred at 80℃ and 300 rpm for 1 hour. After filtration, a biomass-modified solution was obtained. The biomass-modified solution was mixed with Czapek's liquid culture medium at a volume ratio of 0.2:1 to obtain a mixed culture solution. 10% of a microbial inoculum (a mixture of Aspergillus niger, Aspergillus flavus, Zygosacchariformis rouxae, and Omega yeast) was inoculated into the mixed culture solution. Fermentation was carried out at 30℃ and 300 rpm for 48 hours to obtain a fermentation broth. 300 mL of the fermentation broth was mixed with ion-adsorption rare earth ore at a volume ratio of 4 mL:1 g to obtain a mixed slurry. The mixed slurry was stirred at 400 rpm and 20℃ for 20 minutes. After filtration, the supernatant obtained was the mixed rare earth leachate. The elemental concentration of the leachate was analyzed by ICP-MS, and the rare earth leaching rate was found to be 95.96%.

[0068] Comparative Example 1 - No Biomass Modification Liquid Added

[0069] The method is the same as in Example 1, except that the volume ratio of biomass modified liquid to Czapek's liquid culture medium is 0.

[0070] The elemental concentration of the leachate treated by the method in Comparative Example 1 was analyzed by ICP-MS, and the rare earth leaching rate was found to be 85.26%.

[0071] Comparative Example 2 - No Microbial Inoculation

[0072] The method is the same as in Example 1, except that: no microbial strains are inoculated into the mixed culture medium to obtain the fermentation broth.

[0073] The elemental concentration of the leachate treated by the method in Comparative Example 2 was analyzed by ICP-MS, and the rare earth leaching rate was found to be 78.79%.

[0074] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for bioleaching of rare earth minerals using modified biomass-enhanced ion adsorption, characterized in that, Includes the following steps: Biomass is modified with a sulfuric acid solution with a mass concentration of 40% to 80% to obtain a biomass modified solution; The modification involves mixing sulfuric acid solution with biomass and stirring at 60℃~80℃ and 200 rpm~400 rpm for 1h~2h. The biomass-modified liquid is mixed with Czapek's liquid medium to obtain a mixed culture medium; a mixed microbial strain is inoculated into the mixed culture medium to obtain a fermentation broth; the microbial strain is one or more of Aspergillus niger, Aspergillus flavus, Rhus niger, Smut, Omega oryzae, Malassezia, Trichoderma reesei, Cladosporium, Alternaria alternata, and Fusarium oxysporum. The fermentation broth is mixed with ion-adsorption type rare earth ore, stirred, filtered, and the resulting supernatant is the rare earth leachate.

2. The method according to claim 1, characterized in that, The ratio of sulfuric acid solution to biomass is 5 mL to 10 mL: 1 g.

3. The method according to claim 1, characterized in that, The volume ratio of the biomass modified liquid to the Czapek liquid culture medium is 0.1~0.3:

1.

4. The method according to claim 1, characterized in that, Based on the total volume of the mixed culture medium, 5% to 15% of microbial strains are inoculated into the mixed culture medium, wherein the effective viable count of the microbial strains is 0.5 × 10⁻⁶. 9 Cells / mL ~5×10 9 per mL.

5. The method according to claim 1, characterized in that, After inoculating with microbial strains, fermentation was carried out at a temperature of 20℃~35℃ and a stirring speed of 200 rpm~400 rpm for 24h~72h to obtain fermentation broth.

6. The method according to claim 1, characterized in that, The mixing ratio of the fermentation broth to the ion-adsorption type rare earth ore is 2 mL to 4 mL: 1 g.

7. The method according to claim 1, characterized in that, The fermentation broth is mixed with ion-adsorption type rare earth ore and stirred for 20 min to 80 min at a speed of 200 rpm to 400 rpm and a temperature of 20℃ to 50℃. After filtration, the resulting supernatant is the rare earth leachate.

8. The method according to claim 1, characterized in that, The biomass is one or a mixture of several of the following: straw, rice husks, fruit shells, sugarcane bagasse, plant debris, weeds, fallen leaves, vines, and branches.