A method for preparing rare earth bioleaching agents using solid waste

Abstract

This invention discloses a method for preparing rare earth bioleaching agents using solid waste, comprising the following steps: 1) drying and pulverizing the solid waste raw material, then mixing it with deionized water to obtain a raw material slurry; 2) sterilizing the raw material slurry, then adjusting the pH of the raw material slurry, adding liquefying enzyme and activator, and liquefying to obtain a liquefied liquid; 3) saccharification: enzymatically inactivating the liquefied liquid, then cooling it, adding saccharifying enzyme, and saccharifying to obtain a saccharified liquid; 4) enzymatic oxidation: filtering the saccharified liquid, adding glucose oxidase and catalase to the filtrate, and catalytically oxidizing to obtain the leaching agent. This invention uses solid waste as raw material, achieving not only the harmless, resource-based, and sustainable utilization of kitchen waste, but also enabling the rapid preparation of high-purity rare earth bioleaching agents under simple and controllable conditions. The process of this invention is simple, easy to operate, environmentally friendly, has a low impurity rate, and is low in cost, showing promising industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and hydrometallurgy, and specifically relates to a method for preparing rare earth bioleaching agents using solid waste. Background Technology

[0002] Ion-adsorption rare earth deposits (weathering crust leaching rare earth deposits, or simply ion-adsorption rare earth deposits) are an important strategic mineral resource, rich in valuable medium and heavy rare earth elements. Due to their significant strategic value and market demand, they have attracted worldwide attention. Previously, industrial mining of ion-adsorption rare earth deposits commonly used in-situ leaching processes based on cation exchange (primarily ammonium salts). This required high concentrations and large quantities of inorganic salt ions, resulting in severe environmental pollution and ecological damage, significantly limiting their application. Achieving clean and efficient utilization of ion-adsorption rare earth deposits is a serious challenge facing the rare earth industry.

[0003] Bioleaching (biomining, biometallurgy) technology boasts advantages such as high efficiency, low carbon footprint, environmental friendliness, and low cost, making it a crucial direction for the clean and efficient extraction of rare earth elements. According to classical bioleaching theory, the bioleaching mechanism mainly includes direct / contact leaching and indirect / non-contact leaching. In the bioleaching process, microorganisms can directly act on the mineral surface and produce redox, complexation, acid-base, and surface modification reactions through biofilms, or generate metabolic products (organic acids, complexing ligands, Fe...). 3+ Bioleaching (using substances such as iron carriers, amino acids, and proteins) indirectly acts on minerals, thereby transferring valuable elements to the leachate for further separation and recovery. Since the industrial development of ion-adsorption rare earth minerals employs in-situ leaching, numerous imprecise controls (such as ore properties, microbial energy substances, temperature, pH, oxygen content, potential, microbial tolerance components, and extreme environmental conditions) and stringent requirements for in-situ leaching permeability prevent the industrial application of contact bioleaching. Therefore, non-contact leaching has become the primary choice for in-situ biomining of ion-adsorption rare earth minerals. Non-contact leaching involves large-scale cultivation / fermentation (biomanufacturing, biotransformation, biosynthesis) of microorganisms under controlled conditions to obtain a large quantity of microbial metabolite leaching agents (referred to as bioleaching agents) for rare earth leaching, which are then used for in-situ leaching of ion-adsorption rare earth minerals. While bioleaching agents prepared by fermentation can effectively leach rare earth elements, they suffer from several drawbacks, including high costs of energy substrates (primarily glucose), long production cycles, low production efficiency, and demanding process conditions. Furthermore, bioleaching agents prepared by fermentation often contain impurities detrimental to rare earth leaching (such as useless culture medium components and other metabolites like phosphates and oxalic acid). Therefore, there is an urgent need for a method to prepare bioleaching agents that is simple to implement, environmentally friendly, has a low impurity rate, and is cost-effective.

[0004] Food waste is a general term for restaurant waste and kitchen scraps. Its main components include starch, cellulose, protein, lipids, and inorganic salts. It possesses the dual characteristics of both waste and resource, representing a typical "resource in the wrong place." Failure to utilize it properly constitutes a significant waste. Food waste is highly perishable and emits foul odors. Improper handling can not only cause widespread secondary pollution but also potentially trigger serious social problems. Therefore, the clean, harmless, resource-efficient, and sustainable treatment of food waste is an inevitable trend. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing rare earth bioleaching agents using solid waste, aiming to solve the above-mentioned defects in the preparation process of bioleaching agents.

[0006] The method for preparing rare earth bioleaching agents using solid waste provided by this invention includes the following steps:

[0007] 1) Pretreatment: The solid waste raw materials are dried and crushed, and then mixed evenly with deionized water to obtain a raw material slurry;

[0008] 2) Sterilization and liquefaction: Sterilize the raw material slurry, then adjust the pH of the raw material slurry to the set range, add liquefying enzyme and activator, set the process parameters, and liquefy to obtain liquefied liquid;

[0009] 3) Saccharification: The liquefied liquid is inactivated by enzymes, then cooled to the set temperature, saccharifying enzymes are added, process parameters are set, and saccharification is carried out to obtain saccharified liquid;

[0010] 4) Enzymatic oxidation: The saccharified liquid is filtered, glucose oxidase and catalase are added to the filtrate, process parameters are set, and catalytic oxidation is carried out to obtain the leachate.

[0011] Step 1) further includes: drying the solid waste raw material, then grinding it into particles with a particle size of less than 200 mesh using a grinder, and then mixing it evenly with deionized water to obtain a raw material slurry.

[0012] It should be noted that step 1) can increase the specific surface area of ​​solid waste raw materials by pre-treating them, thereby improving the conversion efficiency.

[0013] Preferably, in step 1), the solid waste raw material can be any known starch-rich solid waste, such as one or more combinations of waste bread, waste steamed buns, waste rice, and waste noodles.

[0014] Preferably, in step 1), the mass concentration of the raw material slurry is 5-30%.

[0015] Preferably, step 2) includes: sterilizing the raw material slurry at 121°C for 20 minutes, then adjusting the pH of the raw material slurry to 4.0-7.0, adding liquefying enzyme and activator, setting process parameters, and liquefying to obtain liquefied liquid.

[0016] Solid waste typically contains various microorganisms (fungi, bacteria, molds, etc.). The life activities of these microorganisms consume raw materials and produce a series of byproducts, thus reducing product yield and purity. Therefore, the raw material slurry needs to be sterilized before liquefaction. The addition of activators can accelerate enzyme reaction rates, maintain the optimal conformation of enzyme molecules, and increase enzyme stability and activity range. Liquefaction of the raw material slurry can degrade water-insoluble macromolecular starch particles into water-soluble dextrins and small-molecule oligosaccharides, reduce solution viscosity, increase material flowability, and provide suitable substrates for saccharification. Adjusting appropriate process parameters can reduce the formation of non-fermentable byproducts (mainly maltulose) and improve raw material utilization.

[0017] Preferably, in step 2), the amount of liquefying enzyme used is 5-30 U / g.

[0018] Preferably, in step 2), the activator is one or a combination of calcium chloride and sodium chloride; the mass concentration of the activator in the slurry is 0.1% to 1%.

[0019] Preferably, in step 2), the liquefaction process parameters include: a reaction temperature of 85–105°C, a stirring rate of 100–500 rpm, and a reaction time of 0.2–2 h.

[0020] Preferably, in step 3), the amount of the saccharifying enzyme used is 30-120 U / g.

[0021] Preferably, in step 3), the set temperature is 30-65°C, and the saccharification process parameters include: maintaining a suitable temperature of 30-65°C, a stirring rate of 100-500 rpm, a pH of 4.0-5.0, and a reaction time of 24-60 h.

[0022] Liquefying enzymes exist during the saccharification process, which can lead to an increase in the content of trisaccharides (mainly panose) in the product, thereby reducing the glucose content. Therefore, it is necessary to inactivate the liquefying enzymes to reduce the formation of panose. Furthermore, by adjusting appropriate process parameters, high-quality glucose syrup can be obtained.

[0023] Preferably, in step 4), the amount of glucose oxidase is 10-150 U / g, and the amount of catalase is 50-750 U / g; the catalytic oxidation process parameters include: reaction temperature of 25-65℃, reaction time of 12-120h, pH of 4.5-7, stirring rate of 100-500 rpm, and air flow rate of 1-5 L / min.

[0024] In step 4), under suitable conditions, glucose oxidase is used to catalyze the production of rare earth bioleaching agents from soluble glucose. The byproducts (hydrogen peroxide) in the production process can denature proteins and affect enzyme activity. Therefore, catalase is used to rapidly decompose the byproducts, and the enzyme activity is protected by adjusting the solution pH to 4.5-7.

[0025] Preferably, the main component of the leaching agent is gluconic acid and its salts, and the concentration of gluconic acid and its salts is 5-52 g / L.

[0026] In some specific applications, the rare earth bioleaching agent prepared according to the above method is used to leach ion-adsorbed rare earth minerals, including the following steps: mixing the rare earth bioleaching agent with the ion-adsorbed rare earth minerals, setting process parameters, leaching, and obtaining a leachate after leaching is completed.

[0027] Preferably, the liquid-to-solid ratio of the leaching agent to the ion-adsorption type rare earth ore is (1-10) ml: 1 g; the leaching process parameters include: leaching temperature of 0-40℃, pH of 1-10, and leaching time of 2-24 h.

[0028] The principle of this invention:

[0029] Microbial metabolites (such as organic acids, iron carriers, complexing ligands, amino acids, and proteins) can be used as leaching agents to leach rare earth elements through complexation / chelation. This invention replaces microbial transformation with multi-stage enzyme-linked reactions, utilizing solid waste (starch-rich solid waste) to prepare rare earth microbial metabolite leaching agents at low cost and in a targeted and efficient manner: First, liquefying enzymes break down the hydration of starch particles in the starch-rich solid waste slurry under suitable conditions and hydrolyze them to form a low-viscosity liquefied liquid. Then, saccharifying enzymes hydrolyze the glycosidic bonds in the liquefied liquid to obtain the precursor for preparing ion-adsorption rare earth mineral bioleaching agents. Further, the high specificity and catalytic activity of enzymes are used to efficiently prepare ion-adsorption rare earth mineral bioleaching agents. This achieves resource utilization of starch-rich solid waste while simultaneously completing low-cost, green, and efficient bioleaching of ion-adsorption rare earth minerals, thus facilitating large-scale industrial applications. The beneficial effects of this invention are:

[0030] 1) Compared with traditional rare earth chemical leaching processes, this invention eliminates the need for high-concentration / high-volume inorganic salt cation leaching of rare earths, effectively avoiding environmental pollution and ecological damage; 2) This invention utilizes multi-stage enzyme-linked reactions to replace traditional biological culture / fermentation, using solid waste (starch-rich solid waste) to prepare rare earth bioleaching agents at low cost and high efficiency, making rare earth biometallurgy more economically feasible; 3) This invention uses starch-rich solid waste as raw material, enabling not only the harmless, resource-based, and sustainable utilization of kitchen waste, but also the rapid preparation of high-purity rare earth bioleaching agents under simple and controllable conditions; 4) The enzyme preparations in this invention are environmentally friendly and safe, widely available, and have advantages such as mild reaction, high activity, and few byproducts; 5) The bioleaching agents prepared by this invention are environmentally friendly and safe, and contribute to the degradation of environmental pollutants, soil improvement, and ecological restoration; 6) This invention has a simple process, is easy to operate, is environmentally friendly, has a low impurity rate, and low production costs, making it suitable for large-scale production and showing good prospects for large-scale industrial applications. Detailed Implementation

[0031] To facilitate understanding of the technical solutions of this invention, the invention is further illustrated below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0032] Example 1

[0033] 1) Pretreatment: Dry the waste bread and grind it into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 10%.

[0034] 2) Sterilization and liquefaction: The raw material slurry was sterilized at 121℃ for 20 min, the pH of the raw material slurry was adjusted to 6.0, calcium chloride and 15 U / g liquefying enzyme were added, the mass concentration of calcium chloride in the slurry was 0.8%, and the reaction was carried out at 90℃ with a stirring rate of 170 rpm for 0.5 h to obtain liquefied liquid.

[0035] 3) Saccharification: The liquefied liquid was inactivated by enzyme and cooled to 60°C. 50 U / g saccharifying enzyme was added, and the pH of the solution was adjusted to 4.5. The reaction was carried out at 60°C with a stirring rate of 170 rpm for 48 h to obtain the saccharified liquid.

[0036] 4) Enzymatic oxidation: 70 U / g glucose oxidase and 350 U / g catalase were added to the saccharification solution, and the reaction was continued at 40℃ for 72 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 30.88 g / L by liquid chromatography.

[0037] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 10 g / L and then mixed with the ion-adsorption rare earth ore at a liquid-to-solid ratio of 10 ml: 1 g. The pH was adjusted to 7.5, the temperature to 30℃, and leaching was carried out for 8 hours. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was 91.2%.

[0038] Example 2

[0039] 1) Pretreatment: Dry the waste bread and grind it into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 15%.

[0040] 2) Sterilization and liquefaction: The raw material slurry was sterilized at 121℃ for 20 min, then the pH of the raw material slurry was adjusted to 6.0, sodium chloride and 15 U / g liquefying enzyme were added, the mass concentration of sodium chloride in the slurry was 1%, and the reaction was carried out at 90℃ with a stirring rate of 170 rpm for 0.5 h to obtain liquefied liquid.

[0041] 3) Saccharification: The liquefied liquid was inactivated by enzyme and cooled to 60°C. 50 U / g saccharifying enzyme was added, and the pH of the solution was adjusted to 4.5. The reaction was carried out at 60°C with a stirring rate of 170 rpm for 48 h to obtain the saccharified liquid.

[0042] 4) Enzymatic oxidation: 70 U / g glucose oxidase and 350 U / g catalase were added to the saccharification solution, and the reaction was continued at 40℃ for 72 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 44.1 g / L by liquid chromatography.

[0043] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 20 g / L and then mixed with the ion-adsorption rare earth ore at a liquid-to-solid ratio of 8 ml: 1 g. The pH was adjusted to 7.5, the temperature to 30℃, and leaching was carried out for 8 hours. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was found to be 94.26%.

[0044] Example 3

[0045] 1) Pretreatment: Dry the waste bread and grind it into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 15%.

[0046] 2) Sterilization and liquefaction: The raw material slurry was sterilized at 121℃ for 20 min, then the pH of the raw material slurry was adjusted to 6.5, and calcium chloride, sodium chloride and 15 U / g liquefying enzyme were added. The mass concentration of calcium chloride and sodium chloride in the slurry was 0.3%. The reaction was carried out at 90℃ with a stirring rate of 200 rpm for 0.5 h to obtain the liquefied liquid.

[0047] 3) Saccharification: The liquefied liquid is inactivated by enzyme and cooled to 60°C. 50 U / g saccharifying enzyme is added, the pH of the solution is adjusted to 4.5, and the reaction is carried out at 60°C with a stirring rate of 200 rpm for 48 h to obtain the saccharified liquid.

[0048] 4) Enzymatic oxidation: 70 U / g glucose oxidase and 350 U / g catalase were added to the saccharification solution, and the reaction was continued at 40℃ for 72 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 40.23 g / L by liquid chromatography.

[0049] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 18 g / L and then mixed with ion-adsorption rare earth ore at a liquid-to-solid ratio of 8 ml: 1 g. The pH was adjusted to 7.5, the temperature to 30℃, and leaching was carried out for 8 hours. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was 94.66%.

[0050] Example 4

[0051] 1) Pretreatment: Dry the waste steamed buns and grind them into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 10%.

[0052] 2) Sterilization and liquefaction: The raw material slurry was sterilized at 121℃ for 20 min, then the pH of the raw material slurry was adjusted to 6.5, sodium chloride and 20 U / g liquefying enzyme were added, the mass concentration of sodium chloride in the slurry was 0.6%, and the reaction was carried out at 90℃ with a stirring rate of 200 rpm for 1 h to obtain liquefied liquid.

[0053] 3) Saccharification: The liquefied liquid was inactivated by enzyme and cooled to 55°C. 60 U / g saccharifying enzyme was added, and the pH of the solution was adjusted to 4.5. The reaction was carried out at 55°C with a stirring rate of 200 rpm for 48 h to obtain the saccharified liquid.

[0054] 4) Enzymatic oxidation: 70 U / g glucose oxidase and 350 U / g catalase were added to the saccharification solution, and the reaction was continued at 35℃ for 72 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 46.88 g / L by liquid chromatography.

[0055] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 15 g / L and then mixed with the ion-adsorption rare earth ore at a liquid-to-solid ratio of 8 ml:1 g. The pH was adjusted to 7.0, the temperature was 35℃, and leaching was carried out for 9 hours. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was 94.06%.

[0056] Example 5

[0057] 1) Pretreatment: Dry the waste steamed buns and grind them into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 10%.

[0058] 2) Sterilization and liquefaction: The raw material slurry was sterilized at 121℃ for 20 min, then the pH of the raw material slurry was adjusted to 5.5, calcium chloride and 20 U / g liquefying enzyme were added, the mass concentration of calcium chloride in the slurry was 0.6%, and the reaction was carried out at 100℃ with a stirring rate of 200 rpm for 0.5 h to obtain liquefied liquid.

[0059] 3) Saccharification: The liquefied liquid was inactivated by enzyme and cooled to 55°C. 60 U / g saccharifying enzyme was added, and the pH of the solution was adjusted to 4.5. The reaction was carried out at 55°C with a stirring rate of 200 rpm for 48 h to obtain the saccharified liquid.

[0060] 4) Enzymatic oxidation: 70 U / g glucose oxidase and 350 U / g catalase were added to the saccharification solution, and the reaction was continued at 35℃ for 72 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 45.88 g / L by liquid chromatography.

[0061] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 28 g / L and then mixed with ion-adsorption rare earth ore at a liquid-to-solid ratio of 10 ml: 1 g. The pH was adjusted to 7.0, the temperature to 30℃, and leaching was carried out for 10 h. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was 95.16%.

[0062] Example 6

[0063] 1) Pretreatment: Dry the waste steamed buns and grind them into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 10%.

[0064] 2) Sterilization and liquefaction: Sterilize the raw material slurry at 121℃ for 20 min; then adjust the pH of the raw material slurry to 5.5, add calcium chloride, sodium chloride and 20 U / g liquefying enzyme, the mass concentration of calcium chloride and sodium chloride in the slurry is 0.2%, and react at 100℃ with a stirring rate of 200 rpm for 1 h to obtain liquefied liquid.

[0065] 3) Saccharification: The liquefied liquid was inactivated by enzyme and cooled to 55°C. 60 U / g saccharifying enzyme was added, and the pH of the solution was adjusted to 4.5. The reaction was carried out at 55°C with a stirring rate of 200 rpm for 48 h to obtain the saccharified liquid.

[0066] 4) Enzymatic oxidation: 70 U / g glucose oxidase and 350 U / g catalase were added to the saccharification solution, and the reaction was continued at 35℃ for 72 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 43.88 g / L by liquid chromatography.

[0067] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 25 g / L and then mixed with the ion-adsorption type rare earth ore at a liquid-solid ratio of 10 ml: 1 g. The pH was adjusted to 7.0, the temperature to 30℃, and leaching was carried out for 10 h. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was 95.06%.

[0068] Example 7

[0069] 1) Pretreatment: Dry the waste steamed buns and grind them into particles with a particle size of less than 200 mesh. Take 100g of the crushed raw material and mix it with deionized water to obtain a raw material slurry with a mass fraction of 10%.

[0070] 2) Sterilization and liquefaction: Sterilize the raw material slurry at 121℃ for 20 min; adjust the pH of the raw material slurry to 5.5, add sodium chloride and 20 U / g liquefying enzyme, the mass concentration of sodium chloride in the slurry is 0.6%, and react at 100℃ with a stirring rate of 200 rpm for 1 h to obtain liquefied liquid.

[0071] 3) Saccharification: The liquefied liquid was inactivated by enzyme and cooled to 55°C. 60 U / g saccharifying enzyme was added, and the pH of the solution was adjusted to 4.5. The reaction was carried out at 55°C with a stirring rate of 200 rpm for 48 h to obtain the saccharified liquid.

[0072] 4) Enzymatic oxidation: 80 U / g glucose oxidase and 400 U / g catalase were added to the saccharification solution, and the reaction was continued at 30℃ for 24 h. The pH of the system was adjusted and maintained at 6.0 to obtain the bioextractant. The concentration of gluconic acid in the bioextractant was determined to be 51.68 g / L by liquid chromatography.

[0073] 5) Leaching: The bioleaching agent was diluted to a gluconic acid concentration of 16 g / L and then mixed with the ion-adsorption type rare earth ore at a liquid-solid ratio of 8 ml: 1 g. The pH was adjusted to 7.0, the temperature was 30℃, and leaching was carried out for 8 hours. Samples were taken, and the concentration of rare earth elements in the solution was determined by ICP-OES to calculate the leaching rate. The rare earth element leaching rate was found to be 94.06%.

Claims

1. A method for preparing rare earth bioleaching agents using solid waste, comprising the following steps: 1) Pretreatment: The solid waste raw materials are dried and crushed, and then mixed evenly with deionized water to obtain a raw material slurry; 2) Sterilization and liquefaction: The raw material slurry is sterilized, then the pH of the raw material slurry is adjusted to the set range, liquefying enzyme and activator are added, process parameters are set, and liquefaction is carried out to obtain liquefied liquid; the activator is one or a combination of calcium chloride and sodium chloride; the mass concentration of the activator in the slurry is 0.1~1%; the dosage of the liquefying enzyme is 5~30 U / g; the liquefaction process parameters include: reaction temperature of 85~105 ℃, stirring speed of 100~500 rpm, and reaction time of 0.2~2 h; 3) Saccharification: The liquefied liquid is enzymatically inactivated, then cooled to a set temperature, saccharifying enzyme is added, and process parameters are set to carry out saccharification to obtain a saccharified liquid; the amount of saccharifying enzyme is 30~120 U / g; the set temperature is 30~65 ℃, and the saccharification process parameters include: maintaining a suitable temperature of 30~65 ℃, a stirring rate of 100~500 rpm, a pH of 4.0~5.0, and a reaction time of 24~60 h; 4) Enzymatic oxidation: The saccharified solution is filtered, and glucose oxidase and catalase are added to the filtrate. The process parameters are set to carry out catalytic oxidation to obtain the extractant. The amount of glucose oxidase is 10~150 U / g, and the amount of catalase is 50~750 U / g. The catalytic oxidation process parameters include: reaction temperature of 25~65 ℃, reaction time of 12~120 h, pH of 4.5~7, stirring rate of 100~500 rpm, and air flow rate of 1~5 L / min. Step 1) further includes: drying the solid waste raw material, then grinding it into particles with a particle size of less than 200 mesh using a grinder, and then mixing it evenly with deionized water to obtain a raw material slurry; in step 1), the solid waste raw material is any known solid waste rich in starch, including but not limited to one or more combinations of waste bread, waste steamed buns, waste rice, and waste noodles; the mass concentration of the raw material slurry is 5-40%; The main components of the leaching agent are gluconic acid and its salts, with a concentration of 5~52 g / L.

2. The method according to claim 1, characterized in that, Step 2) includes: sterilizing the raw material slurry at 121℃ for 20 minutes, then adjusting the pH of the raw material slurry to 4.0~7.0, adding liquefying enzyme and activator, setting process parameters, and liquefying to obtain liquefied liquid.

3. A method for leaching ion-adsorption type rare earth ore using a rare earth bioleaching agent prepared according to claim 1, comprising the steps of: mixing the bioleaching agent with the ion-adsorption type rare earth ore, setting process parameters, performing leaching, and obtaining a leachate after leaching is completed; The liquid-to-solid ratio of the bioleaching agent to the ion-adsorption type rare earth ore is (1~10) mL:1g; the leaching process parameters include: The leaching temperature is 0~40 ℃, the pH is 1~10, and the leaching time is 2~24 h.