A high-phosphorus hematite biological dephosphorization method based on micro-electric field stepwise domestication and nutrient slow-release regulation

Abstract

The application discloses a high-phosphorus hematite biological desphosphorization method based on micro-electric field stepwise domestication and nutrient slow-release regulation, and belongs to the technical field of mineral processing and bio-metallurgy. The biological desphosphorization method comprises the following steps: culturing Bacillus subtilis and Bacillus megaterium to the logarithmic growth phase to obtain active bacteria suspension of a combined bacterial flora; placing the active bacteria suspension in different high-phosphorus hematite slurries from low concentration to high concentration, and obtaining a dominant functional bacterial flora under the regulation of micro-electric field and nutrient slow release; culturing the dominant functional bacterial flora to the logarithmic phase, then adding pretreated high-phosphorus hematite powder for leaching, monitoring the pH value, and separating to obtain leaching solution I and leaching residue I; mixing the leaching residue I with a fungal leaching medium, inoculating a fungus Talaromyces for synergistic leaching, and separating to obtain leaching solution II and desphosphorized iron concentrate. The application successfully constructs an efficient, stable and environment-friendly functional bacterial flora + fungus synergistic system, and realizes efficient removal of phosphorus elements in high-phosphorus iron ore in a short period.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and biometallurgical technology, specifically relating to a bio-dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation. Background Technology

[0002] With the rapid development of the steel industry, the demand for iron ore continues to grow. However, the reserves of high-grade iron ore are gradually decreasing, and the utilization of low-grade and complex iron ores is becoming increasingly prominent. my country has abundant iron ore reserves, but the ore types are complex. Among them, high-phosphorus oolitic hematite, due to its high phosphorus content and complex mineral distribution, has not yet been effectively utilized. The phosphorus content in this type of ore usually exceeds 0.3%, and in some cases even exceeds 1%, and hematite is closely associated with apatite and gangue minerals. The presence of phosphorus affects the application of iron ore in the smelting process, increases the difficulty of dephosphorizing molten steel, reduces steel performance, and leads to increased energy consumption and production costs. Therefore, dephosphorization treatment of high-phosphorus hematite is a key link in realizing resource utilization. Currently, dephosphorization technologies for high-phosphorus iron ore mainly include physical beneficiation, hydrometallurgy, and pyrometallurgy. Physical methods have limited effectiveness for complex disseminated ores; hydrometallurgy can achieve a high dephosphorization rate, but it requires a large amount of acid and alkali reagents and generates waste liquid; pyrometallurgical methods can remove some phosphorus, but they have problems such as high energy consumption, large equipment investment and high carbon emissions, making it difficult to meet the needs of green and low-carbon development.

[0003] In recent years, biometallurgical technology has gradually become an important direction for processing complex iron ores due to its advantages such as operation at ambient temperature and pressure, low energy consumption, and small amount of chemical reagents. Some studies have shown that autotrophic bacteria can release impurity elements in minerals through oxidation, but their high requirements for environmental conditions, single metabolic substrate, and slow growth rate limit their application. For example, Chinese patent CN101037724A discloses a method for dephosphorizing phosphorus-containing iron ore, which uses *Thiobacillus ferrooxidans* (Tf bacteria) to directly leach phosphorus-containing iron ore for dephosphorization. However, its leaching efficiency is low, the leaching cycle requires more than 35 days, and it requires the use of finely ground pyrite as a nutrient source, resulting in high energy consumption and operating costs. In contrast, heterotrophic bacteria are highly adaptable and can utilize various organic substrates to metabolize and produce organic acids, chelates, and other substances, which can promote the release of phosphorus from minerals. For example, Chinese patent CN111733324A discloses a method for synergistic removal of phosphorus from high-phosphorus iron ore using acidophilic heterotrophic and acidophilic autotrophic bacteria. The combined use of acidophilic heterotrophic and acidophilic autotrophic bacteria shortens the leaching cycle by 10 days compared to patent CN101037724A. However, this patent uses two types of bacteria with completely different physiological characteristics and metabolic modes, making the bacterial culture, activation, and domestication process complex. In addition, Chinese patent CN101818249A discloses a magnetization roasting-two-step bioleaching method for iron extraction and phosphorus reduction in high-phosphorus oolitic iron ore. The addition of a pretreatment step, magnetization roasting, before bioleaching involves the connection of different processes, making the operation cumbersome. Furthermore, magnetization roasting has extremely high energy consumption and accounts for a large proportion of the cost.

[0004] It is evident that existing technologies still have shortcomings in terms of dephosphorization efficiency, environmental adaptability, and process simplicity. How to select mild and adaptable microbial communities, find auxiliary microbial communities for dephosphorization of high-phosphorus hematite, and achieve efficient dephosphorization while simultaneously preserving iron, thus promoting the green and efficient utilization of resources and the development of low-carbon metallurgy, is a pressing issue that needs to be addressed. Summary of the Invention

[0005] To address the problems of low dephosphorization efficiency, poor microbial community stability, high energy consumption, and secondary pollution in existing high-phosphorus hematite dephosphorization methods, this invention aims to propose a biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation. This method utilizes multiple heterotrophic Bacillus strains to construct a composite microbial community. Through stepwise mineral domestication, low-intensity micro-electric field assistance, and slow-release regulation of nutrients, a functional microbial community with acid resistance, metal resistance, strong metabolic activity, and persistent interfacial interaction capabilities is obtained, and synergistic leaching with fungi is achieved. Under normal temperature and pressure conditions, the composite microbial community and fungi can stably produce organic acids, chelating agents, and extracellular polymers, significantly improving phosphorus leaching efficiency while effectively inhibiting excessive iron leaching.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for biological dephosphorization of high-phosphorus hematite based on micro-electric field acclimatization and nutrient slow-release regulation, comprising the following steps:

[0008] Construction of combined bacterial communities: Bacillus subtilis and Bacillus megaterium were inoculated into LB liquid medium in a certain proportion for pre-culture and cultured to the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community. The construction of the combined bacterial community was carried out in a shaking state.

[0009] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community is placed in different high-phosphorus hematite slurries of varying concentrations from low to high for acclimatization. During the acclimatization process, a micro-electric field is applied, and a controllable release carrier is used to slowly release and supplement carbon and nitrogen sources to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The micro-electric field cascade acclimatization-nutrient slow-release regulation process is in an oscillating state.

[0010] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to the required particle size;

[0011] Bioleaching of dominant functional bacteria: The dominant functional bacteria, after being domesticated by the micro-electric field mineral gradient and nutrient slow-release regulation treatment, were transferred to a bacterial bioleaching container and then inoculated into phosphorus-deficient NBRIP medium. After being cultured to the logarithmic phase, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 5wt.%-15wt.% for bioleaching. During the process, the pH value of the leaching system was monitored regularly to determine whether it was within a stable range, thereby determining the status of the bacterial community. After leaching, leachate I was separated and leaching residue I was washed to remove residual bacterial metabolic acid. The bioleaching process of the dominant functional bacteria was carried out in an oscillating state.

[0012] Fungal co-leaching: Leaching residue I is placed in a fungal co-leaching container and mixed with fungal leaching PDA medium. Then, the leaching fungus Talaromyces is inoculated to carry out fungal co-leaching. After leaching, leachate II is separated and washed to obtain dephosphorized iron concentrate. The fungal co-leaching process is carried out in an oscillating state.

[0013] Furthermore, in the construction of the combined bacterial community, the inoculation amount of Bacillus subtilis and Bacillus megaterium was 5 vol.%-15 vol.%, the pre-culture time was 6 h-12 h, the OD value of the active bacterial suspension of the combined bacterial community was 2.0-3.0, the temperature during the construction of the combined bacterial community was 28℃-40℃, and the shaking speed of the shaker under oscillation was 120 rpm-150 rpm.

[0014] Furthermore, in the construction of the combined microbial community, the composition of the LB liquid culture medium is: 8.0 g / L-12.0 g / L tryptone, 3.0 g / L-7.0 g / L yeast extract, and 8.0 g / L-12.0 g / L NaCl.

[0015] Furthermore, in the micro-electric field cascade acclimatization-nutrient slow-release regulation, the concentration of high-phosphorus hematite slurry used for acclimatization is 1wt.%, 3wt.%, and 5wt.% respectively, from low to high. The electric field strength of the micro-electric field is 0.1V / cm-1.0V / cm. The temperature during the micro-electric field cascade acclimatization-nutrient slow-release regulation process is 28℃-40℃, and the shaking speed of the shaker under oscillation is 120rpm-150rpm.

[0016] Furthermore, in the micro-electric field gradient domestication-nutrient slow-release regulation, the controllable release carrier is starch microspheres or chitosan slow-release microcapsules, the carbon source is glucose or fructose, and the nitrogen source is ammonium nitrate or ammonium sulfate.

[0017] Furthermore, in the pretreatment of high-phosphorus hematite powder, the particle size is 0.038μm-0.074μm.

[0018] Furthermore, in the bioleaching of dominant functional microbial communities, the composition of the phosphorus-deficient NBRIP medium is as follows: 8.0 g / L-12.0 g / L glucose, 0.35 g / L-0.65 g / L magnesium sulfate, 0.35 g / L-0.65 g / L ammonium sulfate, and 0.2 g / L-0.4 g / L potassium chloride;

[0019] The culture time is 24h-48h. When the dominant functional bacteria are cultured to the logarithmic phase, the OD value is 1.2-1.5 and the pH value is 3.5-4.0.

[0020] Furthermore, in the bioleaching of dominant functional bacteria, the bacterial bioleaching container is a continuous reactor, and sterile air is introduced at a rate of 0.5 L / min to 1.0 L / min; the temperature during the bioleaching process is 28℃-40℃, the shaking speed is 120 rpm-150 rpm under oscillation, the pH value is stable within the range of 1.5-2.5, and the leaching time is 6-8 days.

[0021] Furthermore, in the bioleaching of the dominant functional bacterial community, leachate I was obtained by centrifugation at a speed of 8000rpm-10000rpm for 5min-10min.

[0022] Furthermore, in the fungal co-leaching process, the inoculum size of the fungus *Talaromyces* was 0.5 vol.%–2.0 vol.%, and the fungal co-leaching vessel was a continuous reactor with sterile air introduced at a rate of 0.5 L / min–1.0 L / min.

[0023] The PDA medium consists of: 18g / L-20g / L glucose and 180g / L-200g / L potato.

[0024] Leachate II was obtained by centrifugation at a speed of 8000 rpm-10000 rpm for 5 min-10 min.

[0025] During the synergistic leaching of fungi, the temperature was 28℃-40℃, the shaking speed was 120rpm-150rpm, and the leaching time was 4-6 days.

[0026] The total dephosphorization rate in leachate II is ≥58.67%, and the iron loss rate is ≤2.84%.

[0027] This invention employs a combined leaching process of "bacteria first, then fungi," selecting Bacillus subtilis and Bacillus megaterium for combined culture. It utilizes the extracellular secretions (various low-molecular-weight organic acids and phosphatases) produced during their growth and metabolism, through H... + Ions lower the pH of the rhizosphere microenvironment and chemically dissolve insoluble phosphates; organic acid anions (such as citrate and oxalate) can react with cations in phosphate minerals (such as Ca2+). 2+ Fe 3+ Al 3+ The process involves forming stable soluble complexes, releasing phosphorus into the solution and displacing the fixed phosphorus. This creates a mineral structure rich in soluble metal ions, which is then loosened for subsequent fungal leaching. The fungi then take over, leveraging their advantage of complexing and dissolving various minerals in a near-neutral environment. They utilize a variety of organic acids to synergistically acidify and dissolve the minerals, along with iron carrier chelation and extracellular polymers to assist leaching. Simultaneously, the fungal mycelium has extremely high phosphorus absorption and transport efficiency, actively transporting and continuously maintaining a low pH environment. This combination of bacteria and fungi forms a perfect functional relay, converting insoluble phosphorus into effective soluble phosphorus, thereby achieving a high phosphorus removal rate and a low iron loss rate, demonstrating good leaching effect and selectivity.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) By combining Bacillus subtilis and Bacillus megaterium heterotrophic strains, this invention can give full play to the synergistic metabolism and complementary effects (complex microbial community effect) between strains, which can significantly improve phosphorus removal efficiency and microbial community stability; and can adapt to a wider environmental window, which is significantly better than single strain systems.

[0030] (2) In the process of acclimation of the combined microbial community of the present invention with progressively increasing slurry concentration, a micro-electric field and slow-release nutrient regulation are adopted. The micro-electric field can promote cell membrane permeability and metabolic fluidity, accelerate the adaptation of the microbial community to complex ions such as high phosphorus, high iron, and high silicon in the mineral environment, and thus shorten the acclimation period. This results in a dominant microbial community that can maintain stable metabolism even under high mineral load conditions. A controllable release carrier is used to load carbon and nitrogen sources to achieve slow-release of nutrients, avoiding the microbial community from entering the metabolic decline period after rapid consumption of nutrients in the early stage. Slow-release regulation ensures the continuous secretion of metabolites such as organic acids, extracellular polysaccharides, and iron carriers during the leaching cycle, thereby maintaining long-term leaching activity.

[0031] (3) The present invention is easy to operate and belongs to green and low-cost process. The whole process is carried out at normal temperature and pressure, without roasting, acid washing or adding chemical additives, thus avoiding equipment corrosion and secondary pollution problems. The system can be directly applied to shake flask experiments, heap leaching systems and bioreactors, and has good potential for industrial promotion.

[0032] (4) This invention innovatively adopts a mineral cascade domestication model of “bacteria first, then fungi” combined with “micro electric field + nutrient slow release regulation” to successfully construct a highly efficient, stable and environmentally friendly functional microbial community + fungal synergistic system. It breaks through the bottleneck problems of low phosphorus removal rate, poor adaptability and unstable process of existing biological dephosphorization technology. The microbial community synergistic system of this invention has strong adaptability, good leaching effect and selectivity, and can achieve efficient removal of phosphorus from high phosphorus hematite in a short period of time, while taking into account the retention of iron. It provides a new technical path for the resource utilization of high phosphorus iron ore and promotes the green and efficient utilization of resources and the development of low-carbon metallurgy. Attached Figure Description

[0033] Figure 1 The present invention provides a process flow diagram for a biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0035] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation, such as... Figure 1 As shown, it includes the following steps:

[0036] Construction of the combined bacterial community: Bacillus subtilis and Bacillus megaterium were inoculated into LB liquid medium at an inoculum size of 5 vol.%-15 vol.% and pre-cultured for 6-12 h. The composition of LB liquid medium was: 8.0 g / L-12.0 g / L tryptone, 3.0 g / L-7.0 g / L yeast extract, and 8.0 g / L-12.0 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension with an OD value of 2.0-3.0. The temperature during the construction of the combined bacterial community was 28℃-40℃ and the shaking speed was 120 rpm-150 rpm.

[0037] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.1V / cm-1.0V / cm was applied, and carbon and nitrogen sources were slowly supplemented using a controllable release carrier to maintain the long-term stable metabolism of the bacterial community. The controllable release carrier was starch microspheres or chitosan slow-release microcapsules, the carbon source was glucose or fructose, and the nitrogen source was ammonium nitrate or ammonium sulfate. The dominant functional bacterial community was obtained. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 28℃-40℃, and the shaking speed was 120rpm-150rpm.

[0038] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm.

[0039] Bioleaching of dominant functional bacteria: After micro-electric field mineral gradient domestication and nutrient slow-release regulation treatment, the dominant functional bacteria were transferred to a continuous bioleaching reactor and sterile air was introduced at a rate of 0.5 L / min-1.0 L / min. Then, phosphorus-deficient NBRIP medium was inoculated. The composition of the phosphorus-deficient NBRIP medium was: 8.0 g / L-12.0 g / L glucose, 0.35 g / L-0.65 g / L magnesium sulfate, 0.35 g / L-0.65 g / L ammonium sulfate, and 0.2 g / L-0.4 g / L potassium chloride. The culture was carried out for 24-48 hours until the logarithmic growth phase. At this point, the OD value of the dominant functional bacteria was 1. The concentration of the slurry in the leaching system was 5wt.%-15wt.% after adding high-phosphorus hematite powder. The bioleaching process lasted for 6-8 days. During the leaching period, the pH of the leaching system was monitored regularly to ensure it remained stable within the range of 1.5-2.5, thereby determining the state of the bacterial community. After leaching, the system was centrifuged at 8000rpm-10000rpm for 5-10 minutes to obtain leachate I. The leachate residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 28℃-40℃, and the shaking speed was 120rpm-150rpm.

[0040] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional bacteria is placed in a batch or continuous fungal co-leaching reactor, and sterile air is introduced at a rate of 0.5 L / min-1.0 L / min. The mixture is then mixed with fungal leaching PDA medium, which consists of 18 g / L-20 g / L glucose and 180 g / L-200 g / L potato. The leaching fungus Talamomyces is then inoculated at a rate of 0.5 vol.%-2.0 vol.%. Fungal co-leaching lasts for 4-6 days. After leaching, the residue is centrifuged at 8000 rpm-10000 rpm for 5-10 minutes to obtain leaching solution II. The leaching residue II is then washed to obtain dephosphorized iron concentrate. The temperature during the fungal co-leaching process is 28℃-40℃, and the shaking speed is 120 rpm-150 rpm.

[0041] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was ≥58.67%, and the iron loss rate was ≤2.84%.

[0042] The high-phosphorus hematite used in the various embodiments of the present invention is high-phosphorus oolitic hematite from the Wushan mining area of ​​Chongqing.

[0043] Example 1

[0044] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0045] Construction of the combined bacterial community: 15 vol.% inoculum of Bacillus subtilis and 5 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 6 h. The composition of LB liquid medium was: 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.67. The temperature during the construction of the combined bacterial community was 30 ℃ and the shaking speed was 150 rpm.

[0046] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.5V / cm was applied, and starch microspheres with a controllable release carrier were used to supplement the carbon source glucose and nitrogen source ammonium nitrate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 30℃ and the shaking speed was 150rpm.

[0047] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0048] Bioleaching of dominant functional bacteria: After micro-electric field mineral gradient domestication and nutrient slow-release regulation treatment, the dominant functional bacteria were transferred to a continuous bioleaching reactor and sterile air was introduced at a rate of 1 L / min. Then, phosphorus-deficient NBRIP medium was inoculated. The composition of the phosphorus-deficient NBRIP medium was: 10 g / L glucose, 0.5 g / L magnesium sulfate, 0.5 g / L ammonium sulfate, and 0.3 g / L potassium chloride. The culture was carried out for 24 h until the logarithmic growth phase. At this point, the OD value of the dominant functional bacteria was 1.32, and the pH was [not specified]. The pH value was 3.67. Subsequently, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 10 wt.%, and bioleaching was carried out for 6 days. During the leaching period, the pH value of the leaching system was monitored regularly to ensure it remained stable within the range of 1.5-2.5, thereby determining the state of the bacterial community. After leaching, the system was centrifuged at 10,000 rpm for 10 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The bioleaching process of the dominant functional bacteria was carried out at a temperature of 30℃ and a shaking speed of 150 rpm.

[0049] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional bacteria was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 0.5 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 20 g / L glucose and 200 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 1 vol.%, and the fungal co-leaching lasted for 4 days. After leaching, the residue was centrifuged at 10,000 rpm for 10 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 30℃ and a shaking speed of 150 rpm. The dephosphorized iron concentrate contained 49.98 wt.% TFe and 0.50 wt.% P.

[0050] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 63.11%, and the iron loss rate was 2.12%.

[0051] Example 2

[0052] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0053] Construction of the combined bacterial community: 15 vol.% inoculum of Bacillus subtilis and 5 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 6 h. The composition of LB liquid medium was: 8 g / L tryptone, 3 g / L yeast extract, and 8 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.44. The temperature during the construction of the combined bacterial community was 30℃ and the shaking speed was 135 rpm.

[0054] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.5V / cm was applied, and starch microspheres with a controllable release carrier were used to supplement the carbon source glucose and nitrogen source ammonium nitrate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 30℃ and the shaking speed was 135rpm.

[0055] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0056] Bioleaching of dominant functional bacteria: After micro-electric field mineral gradient acclimatization and nutrient slow-release regulation treatment, the dominant functional bacteria were transferred to a continuous bioleaching reactor and sterile air was introduced at a rate of 1 L / min. Then, phosphorus-deficient NBRIP medium was inoculated. The composition of the phosphorus-deficient NBRIP medium was: 10 g / L glucose, 0.65 g / L magnesium sulfate, 0.65 g / L ammonium sulfate, and 0.4 g / L potassium chloride. The culture was carried out for 24 h until the logarithmic growth phase. At this point, the OD value of the dominant functional bacteria was 1.33. The pH value was 3.66. High-phosphorus hematite powder was then added to maintain the slurry concentration in the leaching system at 10 wt.%, and bioleaching was carried out for 6 days. During the leaching period, the pH value of the leaching system was monitored regularly to determine whether it was stable within the range of 1.5-2.5, thereby determining the state of the bacterial community. After leaching, the system was centrifuged at 9000 rpm for 8 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 30℃ and the shaking speed was 135 rpm.

[0057] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional bacteria was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 0.8 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 19 g / L glucose and 190 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 2 vol.%, and fungal co-leaching was carried out for 4 days. After leaching, the residue was centrifuged at 9000 rpm for 8 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 30℃ and a shaking speed of 135 rpm. The dephosphorized iron concentrate contained 49.87 wt.% TFe and 0.51 wt.% P.

[0058] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 62.88%, and the iron loss rate was 2.11%.

[0059] Example 3

[0060] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0061] Construction of the combined bacterial community: 15 vol.% inoculum of Bacillus subtilis and 5 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 6 h. The composition of LB liquid medium was: 12 g / L tryptone, 7 g / L yeast extract, and 12 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.31. The temperature during the construction of the combined bacterial community was 30 ℃ and the shaking speed was 120 rpm.

[0062] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.5V / cm was applied, and a controlled-release carrier, starch microspheres, was used to supplement the carbon source glucose and nitrogen source ammonium nitrate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 30℃ and the shaking speed was 120rpm.

[0063] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0064] Bioleaching of dominant functional bacteria: The dominant functional bacteria, after micro-electric field mineral gradient acclimatization and nutrient slow-release regulation treatment, were transferred to a continuous bioleaching reactor and purged with sterile air at a rate of 0.8 L / min. They were then inoculated with phosphorus-deficient NBRIP medium, composed of 10 g / L glucose, 0.35 g / L magnesium sulfate, 0.35 g / L ammonium sulfate, and 0.2 g / L potassium chloride. The culture was carried out for 24 h until the logarithmic growth phase, at which point the OD value of the dominant functional bacteria was 1.3. 5. The pH value was 3.63. Then, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 15 wt.%, and bioleaching was carried out for 6 days. During the leaching period, the pH value of the leaching system was monitored regularly to determine whether it was stable within the range of 1.5-2.5, thereby determining the status of the bacterial community. After the leaching was completed, the system was centrifuged at 8000 rpm for 5 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 30℃ and the shaking speed was 120 rpm.

[0065] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional microorganisms was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 1 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 18 g / L glucose and 180 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 0.5 vol.%, and fungal co-leaching was carried out for 4 days. After leaching, the residue was centrifuged at 8000 rpm for 5 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 30℃ and a shaking speed of 120 rpm. The dephosphorized iron concentrate contained 49.75 wt.% TFe and 0.53 wt.% P.

[0066] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 61.32%, and the iron loss rate was 2.32%.

[0067] Example 4

[0068] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0069] Construction of the combined bacterial community: 10 vol.% inoculum of Bacillus subtilis and 10 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 10 h. The composition of LB liquid medium was: 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.59. The temperature during the construction of the combined bacterial community was 28 ℃ and the shaking speed was 150 rpm.

[0070] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.1V / cm was applied, and starch microspheres with a controllable release carrier were used to supplement the carbon source glucose and nitrogen source ammonium nitrate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 28℃ and the shaking speed was 150rpm.

[0071] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0072] Bioleaching of dominant functional bacteria: After micro-electric field mineral gradient domestication and nutrient slow-release regulation treatment, the dominant functional bacteria were transferred to a continuous bioleaching reactor and sterile air was introduced at a rate of 0.8 L / min. Then, phosphorus-deficient NBRIP medium was inoculated. The composition of the phosphorus-deficient NBRIP medium was: 12 g / L glucose, 0.5 g / L magnesium sulfate, 0.5 g / L ammonium sulfate, and 0.3 g / L potassium chloride. The culture was carried out for 36 h until the logarithmic growth phase. At this point, the OD value of the dominant functional bacteria was 1.31. The pH value was 3.59. Subsequently, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 15 wt.%, and bioleaching was carried out for 7 days. During the leaching period, the pH value of the leaching system was monitored regularly to determine whether it was stable within the range of 1.5-2.5, thereby determining the status of the bacterial community. After the leaching was completed, the system was centrifuged at 10,000 rpm for 10 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 28℃ and the shaking speed was 150 rpm.

[0073] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional microorganisms was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 0.8 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 20 g / L glucose and 200 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 1 vol.%, and the fungal co-leaching lasted for 5 days. After leaching, the residue was centrifuged at 10,000 rpm for 10 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 28℃ and a shaking speed of 150 rpm. The dephosphorized iron concentrate contained 49.84 wt.% TFe and 0.51 wt.% P.

[0074] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 62.37%, and the iron loss rate was 2.34%.

[0075] Example 5

[0076] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0077] Construction of the combined bacterial community: 10 vol.% inoculum of Bacillus subtilis and 10 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 10 h. The composition of LB liquid medium was: 8 g / L tryptone, 3 g / L yeast extract, and 8 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.42. The temperature during the construction of the combined bacterial community was 28 ℃ and the shaking speed was 120 rpm.

[0078] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.1V / cm was applied, and a controlled-release carrier, chitosan slow-release microcapsules, was used to supplement the carbon source fructose and the nitrogen source ammonium sulfate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 28℃ and the shaking speed was 120rpm.

[0079] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0080] Bioleaching of dominant functional bacteria: The dominant functional bacteria, after micro-electric field mineral gradient acclimatization and nutrient slow-release regulation treatment, were transferred to a continuous bioleaching reactor. Sterile air was introduced at a rate of 0.8 L / min, followed by inoculation with phosphorus-deficient NBRIP medium. The NBRIP medium consisted of 12 g / L glucose, 0.65 g / L magnesium sulfate, 0.65 g / L ammonium sulfate, and 0.4 g / L potassium chloride. The culture was carried out for 36 h until the logarithmic growth phase, at which point the OD value of the dominant functional bacteria was 1.2. 7. The pH value was 3.53. Then, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 15 wt.%, and bioleaching was carried out for 7 days. During the leaching period, the pH value of the leaching system was monitored regularly to determine whether it was stable within the range of 1.5-2.5, thereby determining the status of the bacterial community. After the leaching was completed, the system was centrifuged at 9000 rpm for 8 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 28℃ and the shaking speed was 120 rpm.

[0081] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional bacteria was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 1 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 19 g / L glucose and 190 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 2 vol.%, and the fungal co-leaching lasted for 5 days. After leaching, the residue was centrifuged at 9000 rpm for 8 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 28℃ and a shaking speed of 120 rpm. The dephosphorized iron concentrate contained 49.46 wt.% TFe and 0.53 wt.% P.

[0082] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 60.91%, and the iron loss rate was 2.73%.

[0083] Example 6

[0084] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0085] Construction of the combined bacterial community: 10 vol.% inoculum of Bacillus subtilis and 10 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 10 h. The composition of LB liquid medium was: 12 g / L tryptone, 7 g / L yeast extract, and 12 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.33. The temperature during the construction of the combined bacterial community was 28 ℃ and the shaking speed was 120 rpm.

[0086] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 0.1V / cm was applied, and a controlled-release carrier, chitosan slow-release microcapsules, was used to supplement the carbon source fructose and the nitrogen source ammonium sulfate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 28℃ and the shaking speed was 120rpm.

[0087] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0088] Bioleaching of dominant functional bacteria: The dominant functional bacteria, after micro-electric field mineral gradient acclimatization and nutrient slow-release regulation treatment, were transferred to a continuous bioleaching reactor. Sterile air was introduced at a rate of 0.5 L / min, followed by inoculation with phosphorus-deficient NBRIP medium. The NBRIP medium consisted of 8 g / L glucose, 0.35 g / L magnesium sulfate, 0.35 g / L ammonium sulfate, and 0.2 g / L potassium chloride. The culture was carried out for 36 hours until the logarithmic growth phase. At this point, the OD value of the dominant functional bacteria was 1.2. 9. The pH value was 3.54. Then, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 5 wt.%, and bioleaching was carried out for 8 days. During the leaching period, the pH value of the leaching system was monitored regularly to determine whether it was stable within the range of 1.5-2.5, thereby determining the status of the bacterial community. After the leaching was completed, the system was centrifuged at 8000 rpm for 5 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 28℃ and the shaking speed was 120 rpm.

[0089] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional microorganisms was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 0.5 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 18 g / L glucose and 180 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 1 vol.%, and fungal co-leaching was carried out for 6 days. After leaching, the residue was centrifuged at 8000 rpm for 5 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 28℃ and a shaking speed of 120 rpm. The dephosphorized iron concentrate contained 49.59 wt.% TFe and 0.55 wt.% P.

[0090] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 59.55%, and the iron loss rate was 2.77%.

[0091] Example 7

[0092] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0093] Construction of the combined bacterial community: 5 vol.% inoculum of Bacillus subtilis and 15 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 12 h. The composition of LB liquid medium was: 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.45. The temperature during the construction of the combined bacterial community was 40℃ and the shaking speed was 135 rpm.

[0094] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 1V / cm was applied, and a controlled-release carrier, chitosan slow-release microcapsules, was used to supplement the carbon source fructose and the nitrogen source ammonium sulfate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 40℃ and the shaking speed was 135rpm.

[0095] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0096] Bioleaching of dominant functional bacteria: After micro-electric field mineral gradient domestication and nutrient slow-release regulation treatment, the dominant functional bacteria were transferred to a continuous bioleaching reactor and sterile air was introduced at a rate of 0.5 L / min. Then, phosphorus-deficient NBRIP medium was inoculated. The composition of the phosphorus-deficient NBRIP medium was: 8 g / L glucose, 0.5 g / L magnesium sulfate, 0.5 g / L ammonium sulfate, and 0.3 g / L potassium chloride. The culture was carried out for 48 h until the logarithmic growth phase. At this point, the OD value of the dominant functional bacteria was 1.28. The pH value was 3.58. High-phosphorus hematite powder was then added to maintain the slurry concentration in the leaching system at 5 wt.%, and bioleaching was carried out for 8 days. During the leaching period, the pH value of the leaching system was monitored regularly to ensure it remained stable within the range of 1.5-2.5, thereby determining the state of the bacterial community. After leaching, the system was centrifuged at 10,000 rpm for 10 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 40℃ and the shaking speed was 135 rpm.

[0097] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional microorganisms was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 0.8 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 20 g / L glucose and 200 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 2 vol.%, and fungal co-leaching was carried out for 6 days. After leaching, the residue was centrifuged at 10,000 rpm for 10 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 40℃ and a shaking speed of 135 rpm. The dephosphorized iron concentrate contained 49.94 wt.% TFe and 0.57 wt.% P.

[0098] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 58.67%, and the iron loss rate was 2.83%.

[0099] Example 8

[0100] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation includes the following steps:

[0101] Construction of the combined bacterial community: 5 vol.% inoculum of Bacillus subtilis and 15 vol.% inoculum of Bacillus megaterium, preserved in glycerol, were inoculated into LB liquid medium and pre-cultured for 12 h. The composition of LB liquid medium was: 8 g / L tryptone, 3 g / L yeast extract, and 8 g / L NaCl. The culture was carried out until the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community with an OD value of 2.32. The temperature during the construction of the combined bacterial community was 40℃ and the shaking speed was 150 rpm.

[0102] Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community was sequentially placed in a high-phosphorus hematite slurry of 1wt.%, 3wt.%, and 5wt.% to acclimatize. During the acclimatization process, a micro-electric field with an electric field strength of 1V / cm was applied, and a controlled-release carrier, chitosan slow-release microcapsules, was used to supplement the carbon source fructose and the nitrogen source ammonium sulfate to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The temperature of the micro-electric field cascade acclimatization-nutrient slow-release regulation process was 40℃ and the shaking speed was 150rpm.

[0103] Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to a particle size of 0.038μm-0.074μm. The high-phosphorus hematite powder contains 50.5wt.% TFe and 1.35wt.% P.

[0104] Bioleaching of dominant functional bacteria: The dominant functional bacteria, after micro-electric field mineral gradient acclimatization and nutrient slow-release regulation treatment, were transferred to a continuous bioleaching reactor. Sterile air was introduced at a rate of 0.5 L / min, followed by inoculation with phosphorus-deficient NBRIP medium. The NBRIP medium consisted of 8 g / L glucose, 0.65 g / L magnesium sulfate, 0.65 g / L ammonium sulfate, and 0.4 g / L potassium chloride. The culture was carried out for 48 h until the logarithmic growth phase, at which point the OD value of the dominant functional bacteria was 1.2. 8. The pH value was 3.57. Then, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 5 wt.%. Bioleaching was carried out for 8 days. During the leaching period, the pH value of the leaching system was monitored regularly to determine whether it was stable within the range of 1.5-2.5, thereby determining the status of the bacterial community. After the leaching was completed, the system was centrifuged at 9000 rpm for 5 min to obtain leachate I. Leaching residue I was washed to remove residual bacterial metabolic acid. The temperature of the bioleaching process of the dominant functional bacteria was 40℃ and the shaking speed was 150 rpm.

[0105] Fungal co-leaching: The leaching residue obtained from the bioleaching reaction of dominant functional bacteria was placed in a batch or continuous fungal co-leaching reactor, and sterile air at a rate of 1 L / min was introduced. The residue was mixed with fungal leaching PDA medium, which consisted of 19 g / L glucose and 190 g / L potato. Then, the leaching fungus *Talaromyces* was inoculated at a concentration of 0.5 vol.%, and fungal co-leaching was carried out for 6 days. After leaching, the residue was centrifuged at 9000 rpm for 5 min to obtain leaching solution II. Leaching residue II was washed to obtain dephosphorized iron concentrate. The fungal co-leaching process was carried out at a temperature of 40℃ and a shaking speed of 150 rpm. The dephosphorized iron concentrate contained 49.93 wt.% TFe and 0.57 wt.% P.

[0106] The dephosphorization rate and iron loss rate were calculated to evaluate the leaching effect and selectivity. The total dephosphorization rate in leachate II was 58.73%, and the iron loss rate was 2.84%.

[0107] Comparative Example 1

[0108] A biological dephosphorization method for high-phosphorus hematite based on nutrient slow-release regulation differs from Example 1 in that no micro-electric field was applied during the domestication of the combined microbial community, and the leaching cycle was extended to 18 days due to its weaker metabolic activity. The dephosphorized iron concentrate contained 49.67 wt.% TFe and 0.66 wt.% P, with a dephosphorization rate of 51.87% and an iron loss rate of 3.29%, indicating a low dephosphorization efficiency.

[0109] Comparative Example 2

[0110] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication differs from Example 4 in that nutrient slow-release regulation is used during the combined microbial community domestication process; the dephosphorized iron concentrate contains 47.85 wt.% TFe and 0.71 wt.% P; the dephosphorization rate is only 48.37%, and the iron loss rate is 7.12%. It can be seen that without the effect of nutrient slow-release regulation, the microbial community metabolism is unstable, resulting in a large amount of iron loss.

[0111] Comparative Example 3

[0112] A biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation differs from Example 1 in that the combined bacterial community is replaced with pure *Acidithiobacillus acidophilus*, the culture medium is 9K medium, and the inoculum size is 15 vol.%. The dephosphorized iron concentrate contains 27.36 wt.% TFe and 0.55 wt.% P. The dephosphorization rate is 66.37%, and the iron loss rate is 55.33%. It can be seen that although *Acidithiobacillus acidophilus* can achieve a higher dephosphorization rate, it is accompanied by a large amount of iron dissolution, resulting in an extremely high iron loss rate, which seriously affects the utilization value of the ore. This also shows that the combined bacterial community of the present invention is significantly superior to the traditional autotrophic bacterial system in terms of selectivity.

[0113] In summary, the present invention, based on micro-electric field cascade domestication and nutrient slow-release regulation, is a biological dephosphorization method for high-phosphorus hematite. Under the synergistic leaching of combined bacterial communities (Bacillus subtilis and Bacillus megaterium) and fungi (Talaromyces), it can effectively remove phosphorus from high-phosphorus hematite while ensuring a low iron loss rate, and has good application potential.

Claims

1. A method for biological dephosphorization of high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation, characterized in that, Includes the following steps: Construction of combined bacterial communities: Bacillus subtilis and Bacillus megaterium were inoculated into LB liquid medium in a certain proportion for pre-culture and cultured to the logarithmic growth phase to obtain an active bacterial suspension of the combined bacterial community. The construction of the combined bacterial community was carried out in a shaking state. Micro-electric field cascade acclimatization-nutrient slow-release regulation: The active bacterial suspension of the combined bacterial community is placed in different high-phosphorus hematite slurries of varying concentrations from low to high for acclimatization. During the acclimatization process, a micro-electric field is applied, and a controllable release carrier is used to slowly release and supplement carbon and nitrogen sources to maintain the long-term stable metabolism of the bacterial community and obtain the dominant functional bacterial community. The micro-electric field cascade acclimatization-nutrient slow-release regulation process is in an oscillating state. Pretreatment of high-phosphorus hematite powder: The high-phosphorus hematite powder is dried, crushed and sieved to the required particle size; Bioleaching of dominant functional bacteria: The dominant functional bacteria, after being domesticated by the micro-electric field mineral gradient and nutrient slow-release regulation treatment, were transferred to a bacterial bioleaching container and then inoculated into phosphorus-deficient NBRIP medium. After being cultured to the logarithmic phase, high-phosphorus hematite powder was added to maintain the slurry concentration in the leaching system at 5wt.%-15wt.% for bioleaching. During the process, the pH value of the leaching system was monitored regularly to determine whether it was within a stable range, thereby determining the status of the bacterial community. After leaching, leachate I was separated and leaching residue I was washed to remove residual bacterial metabolic acid. The bioleaching process of the dominant functional bacteria was carried out in an oscillating state. Fungal co-leaching: Leaching residue I is placed in a fungal co-leaching container and mixed with fungal leaching PDA medium. Then, the leaching fungus Talaromyces is inoculated to carry out fungal co-leaching. After leaching, leachate II is separated and washed to obtain dephosphorized iron concentrate. The fungal synergistic leaching process is in an oscillating state.

2. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the construction of the combined bacterial community, the inoculum size of Bacillus subtilis and Bacillus megaterium was 5 vol.%-15 vol.%, the pre-culture time was 6 h-12 h, the OD value of the active bacterial suspension of the combined bacterial community was 2.0-3.0, the temperature during the construction of the combined bacterial community was 28℃-40℃, and the shaking speed of the shaker under oscillation was 120 rpm-150 rpm.

3. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the construction of the combined microbial community, the composition of LB liquid medium is: 8.0 g / L-12.0 g / L tryptone, 3.0 g / L-7.0 g / L yeast extract, and 8.0 g / L-12.0 g / L NaCl.

4. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the micro-electric field gradient acclimatization-nutrient slow-release regulation, the concentration of high-phosphorus hematite slurry used for acclimatization was 1wt.%, 3wt.%, and 5wt.% respectively, from low to high. The electric field strength of the micro-electric field was 0.1V / cm-1.0V / cm. The temperature during the micro-electric field gradient acclimatization-nutrient slow-release regulation process was 28℃-40℃, and the shaking speed of the shaker under oscillation was 120rpm-150rpm.

5. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the micro-electric field gradient domestication-nutrient slow-release regulation, the controllable release carrier is starch microspheres or chitosan slow-release microcapsules, the carbon source is glucose or fructose, and the nitrogen source is ammonium nitrate or ammonium sulfate.

6. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the pretreatment of high-phosphorus hematite powder, the particle size is 0.038μm-0.074μm.

7. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the bioleaching of dominant functional microbial communities, the composition of phosphorus-deficient NBRIP medium is: 8.0 g / L-12.0 g / L glucose, 0.35 g / L-0.65 g / L magnesium sulfate, 0.35 g / L-0.65 g / L ammonium sulfate, and 0.2 g / L-0.4 g / L potassium chloride. The culture time is 24h-48h. When the dominant functional bacteria are cultured to the logarithmic phase, the OD value is 1.2-1.5 and the pH value is 3.5-4.

0.

8. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the bioleaching of dominant functional bacteria, the bacterial bioleaching container is a continuous reactor, and sterile air is introduced at a rate of 0.5L / min-1.0L / min. During the bioleaching process, the temperature is 28℃-40℃, the shaking speed is 120rpm-150rpm, the pH value is stable within the range of 1.5-2.5, and the leaching time is 6-8 days.

9. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the bioleaching of dominant functional bacteria, leachate I was obtained by centrifugation at a speed of 8000rpm-10000rpm for 5min-10min.

10. The biological dephosphorization method for high-phosphorus hematite based on micro-electric field cascade domestication and nutrient slow-release regulation as described in claim 1, characterized in that, In the fungal co-leaching process, the inoculum size of the fungus *Talaromyces* was 0.5 vol.%–2.0 vol.%, and the fungal co-leaching vessel was a continuous reactor with sterile air introduced at a rate of 0.5 L / min–1.0 L / min. The PDA medium consists of: 18g / L-20g / L glucose and 180g / L-200g / L potato. Leachate II was obtained by centrifugation at a speed of 8000 rpm-10000 rpm for 5 min-10 min. During the synergistic leaching of fungi, the temperature was 28℃-40℃, the shaking speed was 120rpm-150rpm, and the leaching time was 4-6 days. The total dephosphorization rate in leachate II is ≥58.67%, and the iron loss rate is ≤2.84%.

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