CN117025985B - A method and application of recovering rare earth elements from red mud using acidophilic thermophilic red algae - Google Patents

Abstract

The invention provides a method for recycling rare earth elements from red mud by utilizing acidophilic thermophilic red algae and application thereof, and belongs to the technical field of resource recycling. The method comprises the steps of mixing red mud leaching liquor, acidophilic thermophilic red algae seed liquor and a carbon source to obtain a treatment liquor to be recovered; and recycling the rare earth elements in the treatment liquid to be recycled by utilizing acidophilic thermophilic red algae, wherein the unicellular acidophilic thermophilic red algae is G.sulfophiaria. Compared with other microalgae recovery technologies, the method for recovering the rare earth elements in the red mud can effectively avoid the pollution and interference of mixed bacteria, and simultaneously avoid complicated sterilization procedures. The method of the invention has the advantages of easy implementation, high treatment efficiency, good absorption effect, low cost and environmental protection.

Description

A method and application of recovering rare earth elements from red mud using acidophilic thermophilic red algae

Technical Field

The invention belongs to the technical field of resource recycling, and in particular relates to a method and application of recycling rare earth elements from red mud by utilizing acidophilic thermophilic red algae.

Background technique

Red mud is a solid waste discharged after alumina is extracted from bauxite. Studies have shown that on average, about 1-2 tons of red mud are produced for every ton of alumina produced, and the annual red mud production in the world is about 150 million tons. my country's alumina production exceeds 25 million tons, and red mud production exceeds 40 million tons, but the comprehensive utilization rate of red mud is only 4%, and the cumulative stockpile of red mud has exceeded 200 million tons. On the one hand, the large-scale stacking of red mud not only occupies a large amount of land, but also consumes a lot of money in the construction and maintenance of the yard. Improper storage can easily cause soil, groundwater and air pollution, and thus deteriorate the ecological environment; on the other hand, red mud contains a large amount of renewable metal elements, especially rich in valuable metals, such as iron, aluminum, calcium, titanium, rare earth and other metal elements. Rare earth elements are considered to be the key and important metals of many high-tech materials. They are known as industrial "gold" and are widely used in new energy, metallurgy, petrochemicals, glass and ceramics, aerospace and other fields. Therefore, the demand for rare earth elements is continuing to grow. Therefore, recovering rare earth metals from red mud can not only achieve resource recycling, but also help reduce environmental pollution and promote the construction of ecological civilization.

At present, there are mainly three methods for recovering rare earth elements from red mud. One is to directly leach rare earth elements from red mud with inorganic acid to generate soluble salts of elements such as cerium, calcium, and titanium. This is a strong acid leaching process, which has the problems of large acid dosage and complicated separation steps. The second is to leach rare earth elements after sulphate roasting of red mud. This method has high sulfuric acid concentration and high roasting temperature involved in the sulphuric acid acidification process. The third is a combination of physical separation and chemical dissolution, such as reducing roasting-magnetic separation to remove iron, acid leaching to remove silicon, and sodium hydroxide solution leaching to remove aluminum to obtain rare earth elements. However, no matter which process is used, it faces the problems of high carbon emissions and environmental pollution caused by high energy consumption and high acid and alkali.

In recent years, the use of biotechnology for environmental and wastewater bioremediation has attracted increasing attention due to its low cost, low carbon and environmental protection, wide variety and excellent performance. In this context, the use of algae to recover rare earth elements in the liquid phase has become a potential biotechnology method. As early as 1997, Hao et al. (1997) studied the process of rare earth element enrichment by living Chlorella. In 2002, Palmieri et al. used dried Sargassum fluitans to remove La ³⁺ . In 2017, Jacinto et al. first reported that living macroalgae can remove and recover rare earths. Although algae have the potential to provide sustainable materials for the removal of rare earths, their efficiency, controllability and convenience of the recovery process still need to be greatly improved. In particular, most existing organisms cannot adapt to the low pH and high metal concentration environment of red mud extracts, which restricts the application and promotion of algae technology for recovering rare earth elements from red mud.

Summary of the invention

In order to solve the above technical problems, the present invention proposes a method and application of recovering rare earth elements from red mud by using acidophilic thermophilic red algae. The method utilizes the ability of acidophilic thermophilic microalgae to survive in extreme environments, allowing them to survive in red mud acid leaching wastewater and absorb the rare earth elements therein, thereby realizing the recovery and secondary utilization of rare earth metal elements.

The present invention proposes a method for recovering rare earth elements from red mud by using acidophilic thermophilic red algae. The method comprises the following steps: mixing red mud extract with acidophilic thermophilic red algae seed liquid to obtain a to-be-recovered treatment liquid, recovering and culturing the mixture, and purifying the to-be-recovered treatment liquid by using the acidophilic thermophilic red algae to recover rare earth elements from the red mud. The acidophilic thermophilic red algae seed liquid is an algae liquid rich in unicellular red algae G. sulphuraria, and the algae species number is G. sulphuraria UTEX 2919. The present invention finds that the acidophilic thermophilic red algae can survive in adverse ecological environments such as acidic hot sulfur springs, sulfur pores, open-pit mines, and endogenous rocks, and can withstand a variety of extreme environments such as high temperature (up to 63° C.), strong acid (pH of 0-4.0), high osmotic pressure (9% salinity), and high concentration of heavy metals (such as chromium and nickel). The acidophilic thermophilic red algae seed liquid has good adsorption properties for heavy metals and the like, and can be used as a heavy metal biosorbent without modification or pretreatment, and has the potential for large-scale production.

Furthermore, the method comprises the following steps: mixing red mud with an extract, oscillating and centrifuging, taking a supernatant to obtain a red mud extract, mixing the red mud extract, an acidophilic and thermophilic red algae seed solution and a carbon source to obtain a treated liquid to be recovered, recovering and culturing the treated liquid to be recovered, separating the acidophilic and thermophilic red algae adsorbed with rare earth elements by centrifugal sedimentation, rinsing with deionized water for 2-3 times, adding a desorbent, and oscillating to achieve the enrichment and recovery of rare earth elements in red mud.

Furthermore, the desorbent is HNO ₃ with a concentration of 0.1 mol/L.

Furthermore, the method for preparing the acidophilic thermophilic red algae seed solution is as follows: at room temperature, the unicellular red algae G. sulphuraria is inoculated into a conical flask containing BG11 culture medium for pre-culture, the initial inoculation concentration is 0.44 g/L, the culture time is 7 days, the light intensity is 2500 lx, and the light-dark ratio is 12h:12h, to obtain the acidophilic thermophilic red algae seed solution.

Furthermore, the extract is a nitric acid solution with a volume fraction of 10%, and the solid-liquid ratio of red mud to the extract is 1kg:50L.

Furthermore, after shaking at room temperature for 10 h, the mixture was centrifuged at 2000 g for 10 min.

Furthermore, in the treated liquid to be recovered, the volume of red mud extract is 10%.

Furthermore, the carbon source includes one or both of glycerol and glucose, and the amount of the carbon source added to the treated liquid to be recovered is 20-40 g/L.

Furthermore, in the treated liquid to be recovered, the initial cell density of the acidophilic and thermophilic red algae is 1.8×10 ⁶ cells/mL.

Furthermore, the recovery culture is carried out at a temperature of 40° C., a humidity of 50-70%, a time of 5-10 days, a pH of 2.5-4, and preferably a pH of 3.5.

Furthermore, the recovery culture is carried out under illumination (full-spectrum LED light), the illumination intensity is 8000-12000Lx, and the light-dark cycle ratio is 16h:8h.

The invention also proposes the application of the method in red mud recovery and treatment.

Compared with the prior art, the present invention has the following advantages and technical effects:

The present invention utilizes the unique absorption performance of single-cell acidophilic thermophilic red algae for rare earth elements, and can achieve rapid absorption of rare earth elements in red mud. The method provided by the present invention is used to recover rare earth elements in red mud. Since the pH in the method is 2.5-4 and the temperature is 40°C, compared with other microalgae recovery technologies, it can effectively avoid contamination and interference from miscellaneous bacteria, and at the same time avoid complicated sterilization procedures. The method of the present invention is easy to implement, has high processing efficiency, good absorption effect, and is also low-cost and green and environmentally friendly.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

Figure 1 is an optical picture of the unicellular red alga G. sulphuraria;

FIG2 is a growth curve of G. sulphuraria cultured in the control group and the RM group;

FIG3 is the results of measuring the total rare earth element content in cells at different pH values in Examples 1-4;

FIG4 is the concentration results of a single rare earth element absorbed and enriched in Example 5 (RM) and Comparative Example 1 (control);

FIG5 is the results of total rare earth element concentrations absorbed and enriched by Example 5 (RM) and Comparative Example 1 (control);

FIG6 shows the total rare earth element concentration results accumulated by G. sulphuraria in Example 3, Example 5, Example 6 and Comparative Examples 2-4.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

The present invention provides a method for recovering rare earth elements from red mud by using acidophilic thermophilic red algae. The red mud extract is mixed with acidophilic thermophilic red algae seed liquid, and the mixture is recovered and cultured to realize the recovery of rare earth elements in the red mud. The acidophilic thermophilic red algae seed liquid is an algae liquid rich in unicellular red algae G. sulphuraria, the algae species number is G. sulphuraria UTEX 2919, which is purchased from the algae seed bank of the University of Texas (UTEX), and the optical picture is shown in FIG1. The acidophilic thermophilic red algae can survive in adverse ecological environments such as acidic hot sulfur springs, sulfur pores, open-pit mines and endogenous rocks, and can withstand high temperature (up to 63° C.), strong acid (pH 0-4.0), high osmotic pressure (9% salinity) and high concentration of heavy metals (such as chromium, nickel) and other extreme environments, and has good adsorption to heavy metals, etc., and can be used as a heavy metal biosorbent without modification or pretreatment, and has the potential for large-scale production.

In an embodiment of the present invention, the method for recovering rare earth elements from red mud using acidophilic thermophilic red algae specifically comprises the following steps:

(1) mixing red mud and extract, shaking, centrifuging, and taking the supernatant to obtain red mud extract;

(2) mixing the red mud extract, the acidophilic and thermophilic red algae seed solution and the carbon source to obtain a treated solution to be recovered;

(3) The treated liquid to be recovered is cultured and centrifuged to separate the acidophilic thermophilic red algae adsorbing the rare earth elements, and the treated liquid is rinsed with deionized water for 2-3 times, a desorbent is added, and the treated liquid is shaken. The acidophilic thermophilic red algae (G. sulphuraria) is used to purify the treated liquid to be recovered, thereby realizing the recovery of rare earth elements in red mud.

Preferably, the desorbent is HNO ₃ with a concentration of 0.1 mol/L.

Preferably, the method for preparing the acidophilic thermophilic red algae seed solution in the embodiment of the present invention is as follows: at room temperature, the unicellular red algae G. sulphuraria is inoculated into a conical flask containing BG-11 culture medium (the culture medium components are shown in Table 1) for pre-culture, the initial inoculation concentration is 0.44 g/L, the culture time is 7 days, the light intensity is 2500 lx, the light-dark ratio is 12h:12h, and the acidophilic thermophilic red algae seed solution is obtained.

Preferably, the extract is a 10% nitric acid solution, and the solid-liquid ratio of red mud to the extract is 1 kg: 50 L. The purpose of using nitric acid to extract red mud is to allow rare earth elements such as scandium and titanium in the red mud to enter the acid leaching solution in the form of ions, so that the acidophilic thermophilic red algae can enrich the rare earth elements through cell metabolism to achieve the recovery of rare earth elements.

Preferably, in step (1), after shaking at room temperature for 10 hours, centrifugation is performed at 2000 g for 10 minutes. After shaking and centrifugation, most of the rare earth elements in the red mud can be transferred into the liquid phase in the form of ions under acid leaching conditions.

Preferably, the volume of red mud extract in the treated liquid to be recovered is 10%.

Preferably, the carbon source includes one or both of glycerol or glucose, and the amount of the carbon source added to the treated liquid to be recycled is 20-40 g/L. The role of adding the carbon source is to enable the microalgae to grow heterotrophically or mixotrophically using the added carbon source, which can promote the growth and metabolism of the microalgae and increase the enrichment rate of the microalgae for rare earth elements.

Preferably, in the treated liquid to be recycled, the initial cell density of the acidophilic thermophilic red algae is 1.8×10 ⁶ cells/mL. The initial cell density of the acidophilic thermophilic red algae is controlled to control the biomass concentration of the acidophilic thermophilic red algae. Too high a concentration will cause the acidophilic thermophilic red algae to compete with light, nutrients and other substances, inhibiting the growth of microalgae. Too low a concentration will cause the acidophilic thermophilic red algae to reduce the enrichment efficiency of rare earth elements.

Preferably, the temperature of the recovery culture is 40°C, the humidity is 50-70%, the time is 5-10 days, the pH is 2.5-4, preferably, the pH is 3.5. The key point of the recovery culture process is to adjust the appropriate culture conditions to achieve the maximum enrichment rate of rare earth elements by acidophilic thermophilic red algae.

Preferably, the recovery culture is carried out under illumination (full spectrum LED light), the illumination intensity is 8000-12000Lx, and the light-dark cycle ratio is 16h:8h. Under illumination, the acidophilic and thermophilic red algae enrich rare earth elements through cell metabolism.

All raw materials used in the embodiments of the present invention are purchased from commercial sources.

The room temperature in the embodiments of the present invention refers to 25±2°C.

In the embodiments of the present invention, the red mud is collected from the red mud dump of an alumina production enterprise in a certain city.

Tolerance of G. sulphuraria to red mud extract

The red mud and the extract (10% nitric acid solution by volume) were mixed at a solid-liquid ratio of 1:50 (kg·L ^-1 ), and after shaking at room temperature for 10 hours, the mixture was centrifuged at 2000g for 10 minutes, and the supernatant was taken to obtain the red mud extract; the acidophilic thermophilic red algae seed solution (G. sulphuraria) was inoculated into 300 mL of 2MA medium containing red mud extract (RM) (the composition of the medium is shown in Table 2, and the content of the red mud extract in the 2MA medium is 30 mL), which is the RM group, and the initial OD ₇₀₀ was determined to be 0.1, and the culture conditions were 40°C and aerated culture under 10000Lx light. After inoculation, the OD ₇₀₀ value of the red algae culture was detected every day, and a growth curve was prepared. The acidophilic thermophilic red algae seed solution (G. sulphuraria) directly cultured in 2MA medium was used as the control group to observe the tolerance of G. sulphuraria to the red mud extract, and the growth curve results are shown in Figure 2.

Table 2 Composition of 2MA medium

As can be seen from Figure 2, the growth curve of G. sulphuraria cultured in 2MA medium (control group) is not much different from the growth curve of G. sulphuraria cultured in 2MA medium added with red mud extract (RM) (RM group), which shows that G. sulphuraria has a relatively high tolerance to red mud extract (RM), so G. sulphuraria can be applied to red mud recovery and treatment. The technical solution of the present invention is further described by examples below. Specific examples are as follows:

Example 1

(1) Red mud and an extract (10% nitric acid solution by volume) were mixed at a solid-liquid ratio of 1:50 (kg·L ^-1 ), shaken at room temperature for 10 h, and then centrifuged at 2000 g for 10 min to obtain a supernatant to obtain a red mud extract;

(2) mixing the red mud extract, the acidophilic thermophilic red algae seed solution and the carbon source (glucose, added in the to-be-recovered treatment liquid in an amount of 40 g/L) to obtain the to-be-recovered treatment liquid, wherein the volume of the red mud extract in the to-be-recovered treatment liquid is 10%, and the initial cell density of the acidophilic thermophilic red algae is 1.8×10 ⁶ cells/mL;

(3) The treated liquid to be recovered is cultured at a temperature of 40°C, a humidity of 70%, a time of 10 days, a pH of 2.5, under a full-spectrum LED lamp, a light intensity of 10,000 Lx, a light-dark cycle ratio of 16 h:8 h, and the acidophilic thermophilic red algae enriched with rare earth elements are recovered by centrifugal sedimentation, rinsed with deionized water 2-3 times, and mixed with the acidophilic thermophilic red algae using 0.1 mol/L _HNO3 as a desorbent and fully shaken to desorb the rare earth ions enriched in the algae cells. The treated liquid to be recovered is purified by the acidophilic thermophilic red algae (G. sulphuraria), thereby realizing the recovery of rare earth elements in red mud.

In this embodiment, the rare earth elements in the red mud in the treatment liquid to be recovered are enriched by acidophilic thermophilic red algae (G. sulphuraria), and further separated to achieve the recovery of rare earth elements in the red mud.

Example 2

Same as Example 1, except that the pH of the recovery culture is 3.

Example 3

Same as Example 1, except that the pH of the recovery culture is 3.5.

Example 4

Same as Example 1, except that the pH of the recovery culture is 4.

Example 5

(1) Red mud was mixed with an extract (10% nitric acid solution by volume, solid-liquid ratio of 1:50 (kg·L ^-1 )), shaken at room temperature for 10 h, centrifuged at 2000 g for 10 min, and the supernatant was collected to obtain a red mud extract;

(2) mixing the red mud extract, the acidophilic thermophilic red algae seed solution and the carbon source (glucose, added in the recovery treatment liquid at an amount of 40 g/L) to obtain the recovery treatment liquid, wherein the volume of the red mud extract in the recovery treatment liquid is 10%, and the initial cell density of the acidophilic thermophilic red algae is 1.8×10 ⁶ cells/mL;

(3) The treated liquid to be recovered is cultured at a temperature of 40°C, a humidity of 50%, a time of 10 days, a pH of 3.5, under a full-spectrum LED lamp, a light intensity of 10,000 Lx, a light-dark cycle ratio of 16 h:8 h, and the acidophilic thermophilic red algae enriched with rare earth elements is recovered by centrifugal sedimentation, rinsed with deionized water 2-3 times, and mixed with the acidophilic thermophilic red algae using 0.1 mol/L _HNO3 as a desorbent and fully shaken to desorb the rare earth ions enriched in the algae cells. The treated liquid to be recovered is purified by the acidophilic thermophilic red algae (G. sulphuraria), thereby realizing the recovery of rare earth elements in red mud.

Example 6

(1) red mud and an extract (10% nitric acid solution by volume, solid-liquid ratio of 1:50 (kg/L)) were mixed, shaken at room temperature for 10 h, centrifuged at 2000 g for 10 min, and the supernatant was collected to obtain a red mud extract;

(2) mixing the red mud extract, the acidophilic thermophilic red algae seed solution and the carbon source (glucose, added in the to-be-recovered treatment liquid in an amount of 40 g/L) to obtain the to-be-recovered treatment liquid, wherein the volume of the red mud extract in the to-be-recovered treatment liquid is 10%, and the initial cell density of the acidophilic thermophilic red algae is 1.8×10 ⁶ cells/mL;

(3) The treated liquid to be recovered is cultured at a temperature of 40°C, a humidity of 60%, a time of 10 days, a pH of 3.5, under a full-spectrum LED lamp, a light intensity of 12000Lx, a light-dark cycle ratio of 16h:8h, and the acidophilic thermophilic red algae enriched with rare earth elements are recovered by centrifugal sedimentation, rinsed with deionized water 2-3 times, mixed with 0.1mol/L _HNO3 as a desorbent and fully shaken to desorb the rare earth ions enriched in the algae cells, and the acidophilic thermophilic red algae (G. sulphuraria) are used to purify the treated liquid to be recovered, thereby realizing the recovery of rare earth elements in red mud.

Comparative Example 1

The same as Example 5, except that no red mud extract is added: the acidophilic thermophilic red algae seed solution and the carbon source (glucose, added in an amount of 40 g/L in the treated liquid to be recovered) are mixed to obtain a treated liquid to be recovered, and the initial cell density of the acidophilic thermophilic red algae is 1.8×10 ⁶ cells/mL; the treated liquid to be recovered is recovered and cultured at a temperature of 40° C., a humidity of 50%, a time of 10 d, a pH of 3.5, under a full-spectrum LED lamp, a light intensity of 10000 Lx, and a light-dark cycle ratio of 16h:8h.

Comparative Example 2

The same as Example 5, except that the amount of glucose added to the treated liquid to be recovered is 15 g/L.

Comparative Example 3

The same as Example 5, except that the recovery culture time in step (3) is 4 days, the recovery culture temperature is 40°C, the humidity is 50%, the time is 10 days, the pH is 3.5, and it is carried out under full-spectrum LED light, the light intensity is 10000Lx, and the light-dark cycle ratio is 16h:8h.

Comparative Example 4

Same as Example 6, except that the light intensity is 15000 Lx, the temperature of the recovery culture is 40°C, the humidity is 60%, the time is 10 days, the pH is 3.5, it is carried out under full-spectrum LED light, and the light-dark cycle ratio is 16h:8h.

Performance Testing

After the growth of G. sulphuraria entered the stable phase, the algae cells in the embodiment and the comparative example were collected by centrifugation at 2000 g, and the rare earth elements absorbed and enriched in the red algae were detected by ICP-MS.

The experimental results of Examples 1-4 show that when the culture pH is between 2.5-4.0, red algae have an enrichment effect on cerium (Ce), lanthanum (La), yttrium (Y), neodymium (Nd), praseodymium (Pr), samarium (Sm), and gadolinium (Gd). In addition, the results of the determination of the total rare earth element content in cells at different pH values in Examples 1-4 are shown in Figure 3. As can be seen from Figure 3, when the pH value is 3.5, the enrichment efficiency is the highest; when the pH value is 2.5, the enrichment efficiency is relatively low. Therefore, the optimal culture pH value for red algae to recover rare earth elements from red mud is about 3.5.

The concentration of a single rare earth element absorbed and enriched in Example 5 and Comparative Example 1 (control) is measured and shown in FIG4 and Table 3.

Table 3 Enrichment effect of Example 5 and Comparative Example 1 on each rare earth element (μg/g dry weight)

Y La Ce Pr Nd Sm Eu G Tb Dy Er Tm Yb Comparative Example 1 0.21 0.22 0.35 0.34 0.35 0.30 0.25 0.41 0.23 0.33 0.42 0.53 1.12 Example 5 10.31 10.74 26.42 4.82 16.14 3.42 1.24 3.11 0.54 2.83 1.51 0.33 2.32

From Figure 4 and Table 3, it can be seen that G. sulphuraria has an absorption and enrichment effect on cerium (Ce), lanthanum (La), yttrium (Y), neodymium (Nd), praseodymium (Pr), samarium (Sm), and gadolinium (Gd), and has a better absorption effect on Ce, Nd, La, and Y.

The results of the total rare earth element concentration absorbed and enriched in Example 5 and Comparative Example 1 (control) are shown in Figure 5. As can be seen from Figure 5, the total rare earth element concentration accumulated in the biomass of G. sulphuraria in Example 5, relative to that in Comparative Example 1, the rare earth concentration absorbed in the algae cells reached 121.5 μg/g dry weight, proving that this type of red algae can survive in the acidic red mud extract and has a good enrichment effect on the rare earth metals in the red mud extract.

The results of the total rare earth element concentration accumulated in the biomass of G. sulphuraria in the methods of Examples 3, 5, 6 and Comparative Examples 2-4 are shown in Figure 6. The total rare earth element concentration accumulated in the biomass of G. sulphuraria in Example 5 was slightly lower than that in Example 3. The rare earth concentrations absorbed in the algae cells of Examples 3 and 5 reached 125.1 μg/g and 121.5 μg/g dry weight, respectively, proving that the red algae can achieve a higher enrichment efficiency under the culture condition of 50-70% humidity; the total rare earth element concentration accumulated in the biomass of G. sulphuraria in Example 5 was much higher than that in Comparative Examples 2 and 3, indicating that the red algae can achieve a higher enrichment efficiency when the carbon source (glucose) addition amount is less than 20 g/L. Or the efficiency of enriching rare earth elements under the culture condition of less than 5 days is very low, which proves that the suitable culture condition of this red algae is a carbon source addition amount of 20-40g/L and a culture time of 5-10d; the total rare earth element concentration accumulated in the biomass of G.sulphuraria in Example 6 is much higher than that in Comparative Example 4, which proves that when the light intensity is higher than 12000lx, the enrichment efficiency of acidophilic thermophilic red algae decreases, and the suitable culture condition of this red algae is under full-spectrum LED lamp, the light intensity is 8000-12000Lx, and the light-dark cycle ratio is 16h:8h.

The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims (5)

1. A method for recovering rare earth elements from red mud using acidophilic thermophilic red algae, characterized in that red mud extract is mixed with acidophilic thermophilic red algae seed solution, and the acidophilic thermophilic red algae is used for purification to achieve recovery of rare earth elements in red mud, wherein the acidophilic thermophilic red algae seed solution is an algae solution rich in unicellular red algae G. sulphuraria; specifically comprising the following steps: The red mud is mixed with the extract, shaken, centrifuged, and the supernatant is taken to obtain a red mud extract, the red mud extract, the acidophilic thermophilic red algae seed solution and the carbon source are mixed to obtain a treatment solution to be recovered, the treatment solution to be recovered is recovered and cultured, the acidophilic thermophilic red algae adsorbed with rare earth elements are separated by centrifugal sedimentation, washed, a desorbent is added, and shaken to achieve the enrichment and recovery of rare earth elements in the red mud; The extract is a nitric acid solution with a volume fraction of 10%, and the solid-liquid ratio of red mud to the extract is 1kg:50L; The carbon source includes one or both of glycerol and glucose, and the amount of the carbon source added to the treated liquid to be recovered is 20-40 g/L; The pH of the recovery culture is 3 to 4; The recovery culture temperature is 40°C, the humidity is 50-70%, and the time is 5-10 days; The recovery culture is carried out under light, the light intensity is 8000-12000Lx, and the light-dark cycle ratio is 16h:8h. 2. The method for recovering rare earth elements from red mud using acidophilic and thermophilic red algae according to claim 1, characterized in that after shaking at room temperature for 10 hours, centrifugation is performed at 2000g for 10 minutes. 3. The method for recovering rare earth elements from red mud using acidophilic and thermophilic red algae according to claim 1, characterized in that the volume of the red mud extract in the treated liquid to be recovered is 10%. 4. The method for recovering rare earth elements from red mud using acidophilic thermophilic red algae according to claim 1, characterized in that the initial cell density of the acidophilic thermophilic red algae in the treated liquid to be recovered is 1.8×10 ⁶ cells/mL. 5. Application of the method according to any one of claims 1 to 4 in red mud recovery and treatment.