CN115745003B - A kind of iron magnesium aluminum carbonate type hydrotalcite material prepared by red mud and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of hydrotalcite materials, and provides a method for preparing an iron-magnesium-aluminum carbonate hydrotalcite material from red mud, which comprises the following steps: sequentially washing the red mud with water to remove alkali and drying to obtain neutral red mud; mixing neutral red mud with a magnesium-containing reagent and water, and then performing mechanochemical treatment in a CO ₂ atmosphere to obtain an iron-magnesium-aluminum carbonate hydrotalcite material; the mechanochemical treatment is ball milling. The invention causes the red mud and the magnesium-containing reagent to generate lattice defects or distortion through ball milling, thereby activating the solid material red mud and the magnesium-containing reagent, improving the activity of solid reaction and promoting the generation of hydrotalcite materials. The results of the examples show that the preparation method provided by the invention is simple to operate and short in flow, and the alumina and the ferric oxide do not need to be extracted first or the bimetallic oxide is prepared first.

Description

A ferromagnesium aluminum carbonate type hydrotalcite material prepared from red mud and its preparation method and application

Technical Field

The invention relates to the technical field of hydrotalcite materials, and in particular to an iron-magnesium-aluminum-carbonate type hydrotalcite material prepared from red mud, and a preparation method and application thereof.

Background technique

Red mud is an industrial solid waste discharged after alumina is extracted from bauxite. The byproduct red mud produced by producing 1 ton of alumina is about 1.0 to 1.8 tons. my country is not only a country with a large amount of bauxite reserves, but also a country with alumina production. It produces more than 100 million tons of red mud solid waste every year, resulting in a large amount of red mud storage. These red mud dumps not only occupy land resources but also have a serious impact on the surrounding environment.

Hydrotalcite compounds (LDHs) are a new type of inorganic functional materials with a layered structure. LDHs are composed of positively charged main layers and interlayer anions assembled through non-covalent interactions. Its structure is similar to that of brucite Mg(OH) ₂ , with unit layers formed by shared edges of MgO ₆ octahedrons. Therefore, it has catalytic and adsorption properties and can be used in the environmental field, especially in the reclamation of contaminated soil and the purification of sewage. The traditional method of preparing hydrotalcite from red mud is to first extract aluminum oxide and iron oxide from red mud, and then use them as raw materials to prepare hydrotalcite. However, this method is complicated to operate and has a long process. Although the prior art CN1600690C also discloses a method for preparing hydrotalcite using Bayer red mud as raw material, 1) preparing a slurry with a hydroxide or oxide of a divalent metal element and red mud; 2) dehydrating the slurry, air-drying or baking, and calcining at 450-750°C for 2-5 hours to obtain a bimetallic oxide; 3) adding the bimetallic oxide obtained in step 2) to a solution of a soluble carbonate or bicarbonate and continuously stirring for 5-10 hours, then filtering or centrifugally dehydrating, washing, dehydrating, air-drying or baking, and grinding to obtain hydrotalcite. However, this method also first mixes red mud with a hydroxide or oxide of a divalent metal element and then calcines to obtain a bimetallic oxide, and then mixes the obtained bimetallic oxide with a carbonate or bicarbonate to prepare hydrotalcite, which also has the problems of complex operation and long process flow.

Summary of the invention

The object of the present invention is to provide an ferromagnesium aluminum carbonate type hydrotalcite material prepared from red mud, and a preparation method and application thereof. The preparation method provided by the present invention is simple to operate, has a short process, and does not require the extraction of aluminum oxide and iron oxide or the preparation of bimetallic oxides in advance.

In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

The present invention provides a method for preparing ferromagnesium aluminum carbonate type hydrotalcite material by using red mud, comprising the following steps:

(1) washing, de-alkaliizing and drying the red mud in sequence to obtain neutral red mud;

(2) Mixing the neutral red mud obtained in step (1) with a magnesium-containing reagent and water, and then subjecting the mixture to a mechanochemical treatment in a _CO2 atmosphere to obtain an ferromagnesium aluminum carbonate-type hydrotalcite material; the mechanochemical treatment is ball milling.

Preferably, the red mud in step (1) has a _Fe2O3 content of _5-30 %, _{an Al2O3} content of 10-30%, a MgO content of 0.5-5%, a _SiO2 content of 25-60%, and an Al(OH) ₃ content of 5-20%.

Preferably, the end point of the water washing and de-alkali treatment in step (1) is when the pH of the washing solution is 6.5 to 7.5.

Preferably, the drying temperature in step (1) is 50-80° C., and the drying time is 30-120 min.

Preferably, in step (2), the mass of the magnesium-containing reagent is 5-20% of the mass of the neutral red mud, and the mass of water is 2-8% of the mass of the neutral red mud.

Preferably, the magnesium-containing reagent in step (2) comprises one or more of MgO, MgCO ₃ , Mg(OH) ₂ and magnesium-containing waste.

Preferably, in the step (2), the ball-to-material ratio of the ball milling is 5 to 10, the rotation speed of the ball milling is 500 to 700 rpm/min, and the ball milling time is 120 to 240 min.

Preferably, the grinding balls used in the ball milling in step (2) are made of zirconium oxide, and the grinding balls used in the ball milling include grinding balls with diameters ranging from 3 to 15 mm.

The present invention provides a ferromagnesium aluminum carbonate type hydrotalcite material prepared by the preparation method described in the above technical solution, comprising 10-35wt% ferromagnesium aluminum carbonate type hydrotalcite, 24-50wt% _SiO2 , 5-20wt% _Al2O3 , 0.1-18wt% Al(OH) _{3 ,} and 0.1-25wt% _{Fe2O3 .}

The present invention also provides the use of the ferromagnesium aluminum carbonate type hydrotalcite material described in the above technical solution in removing organic pollutants.

The present invention provides a method for preparing an ferromagnesium aluminum carbonate type hydrotalcite material from red mud, comprising the following steps: (1) washing the red mud with water, de-alkaliizing and drying the red mud in sequence to obtain neutral red mud; (2) mixing the neutral red mud obtained in the step (1) with a magnesium-containing reagent and water, and then subjecting the mixture to a mechanochemical treatment in a _CO2 atmosphere to obtain an ferromagnesium aluminum carbonate type hydrotalcite material; the mechanochemical treatment is ball milling. The present invention uses red mud as a raw material, first subjecting the red mud to de-alkali and drying to obtain neutral red mud, and then subjecting the mixture to a magnesium-containing reagent and water, and subjecting the mixture to a ball milling in a _CO2 atmosphere to obtain an ferromagnesium aluminum carbonate type hydrotalcite material. The present invention causes lattice defects or distortions in the red mud and the magnesium-containing reagent through ball milling, and generates atomic groups and exo-excited electrons on the original surface and the newly crushed surface, thereby activating the solid material red mud and the magnesium-containing reagent, improving the activity of the solid reaction, and promoting the generation of the hydrotalcite material. The mechanochemical treatment in the present invention exposes Fe ³⁺ and Al ³⁺ on the surface of red mud and Mg ²⁺ on the surface of magnesium-containing reagent, and then, with the addition of water and CO ₂ , a chemical reaction occurs under the action of mechanochemistry, and finally an iron-magnesium-aluminum-carbonate-type hydrotalcite material is generated. The results of the examples show that the preparation method provided by the present invention is simple to operate, has a short process, and does not require the extraction of aluminum oxide and iron oxide or the preparation of bimetallic oxides in advance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a method for preparing ferromagnesium aluminum carbonate type hydrotalcite material using red mud provided by the present invention;

FIG2 is an XRD diagram of the red mud used in Example 1 of the present invention;

FIG3 is an XRD diagram of the iron magnesium aluminum carbonate type hydrotalcite material prepared in Example 1 of the present invention;

FIG. 4 is a diagram showing the removal effect of Rhodamine B by the ferromagnesium aluminum carbonate type hydrotalcite material and red mud prepared in Examples 1 to 3 of the present invention.

Detailed ways

The present invention provides a method for preparing ferromagnesium aluminum carbonate type hydrotalcite material by using red mud, comprising the following steps:

(1) washing, de-alkaliizing and drying the red mud in sequence to obtain neutral red mud;

(2) The neutral red mud obtained in step (1) is mixed with a magnesium-containing reagent and water, and then subjected to a mechanochemical treatment in a CO2 atmosphere to obtain an iron-magnesium-aluminum carbonate-type hydrotalcite material.

The invention sequentially washes, de-alkalis and dries the red mud to obtain neutral red mud. The invention makes the red mud neutral by washing with water to prepare the ferromagnesium aluminum carbonate type hydrotalcite material.

The present invention has no particular limitation on the source of the red mud, and the industrial solid waste discharged after the alumina is extracted from bauxite, which is well known to those skilled in the art, can be used. In the present invention, the red mud preferably includes combined process red mud, Bayer process red mud or sintering process red mud.

In the present invention, the mass content of _Fe2O3 in the red mud is preferably 5-30%, _{more preferably 10-30%; the mass content of Al2O3 in the} red mud is preferably 10-30%, more preferably 10-25%; the mass content of MgO in the red mud is preferably 0.5-5%, more preferably 0.5-2.5%; the mass content of _SiO2 in the red mud is preferably 25-60%, more preferably 27-50%; the mass content of Al(OH) ₃ in the red mud is preferably _5-20 %, more preferably 8-16%. The present invention preferably uses red mud _{with mass contents of Fe2O3, Al2O3 , MgO} , _SiO2 and Al(OH) ₃ within the above ranges as raw materials, which is conducive to obtaining ferromagnesian aluminum carbonate type hydrotalcite materials.

The present invention has no special limitation on the operation of water washing and de-alkali treatment, and the water washing technical scheme familiar to those skilled in the art can be adopted. In the present invention, the end point of water washing and de-alkali treatment is preferably a pH of the washing liquid of 6.5 to 7.5, more preferably 7 to 7.5.

In the present invention, the drying temperature is preferably 50 to 80° C., more preferably 60 to 70° C.; the drying time is preferably 30 to 120 min, more preferably 50 to 100 min.

After obtaining neutral red mud, the present invention mixes the neutral red mud with a magnesium-containing reagent and water, and then performs a mechanochemical treatment in a _CO2 atmosphere to obtain an iron-magnesium-aluminum-carbonate-type hydrotalcite material. The present invention mixes neutral red mud with a magnesium-containing reagent and water, and then performs a mechanochemical treatment in a _CO2 atmosphere to obtain an iron-magnesium-aluminum-carbonate-type hydrotalcite material.

In the present invention, the following chemical transformation occurs during the preparation process of the ferromagnesium aluminum carbonate type hydrotalcite material:

Mg ² +Fe ³⁺ +Al ³⁺ +H ₂ O+CO ₂ →[Mg _1-x (Al,Fe) _x (OH) ₂ ] ^x+ [(CO ₃ ) _x/2 ·nH ₂ O] ^x- ;

, X = 0.17 ~ 0.33.

The present invention has no special limitation on the operation of mixing the neutral red mud with the magnesium-containing reagent and water, and a mixing technical solution well known to those skilled in the art may be adopted.

In the present invention, the mass of the magnesium-containing reagent is preferably 5-20% of the mass of the neutral red mud, and more preferably 5-18%. The magnesium-containing reagent in the present invention is used to provide the magnesium element in the hydrotalcite. The present invention preferably controls the mass of the magnesium-containing reagent within the above range to ensure the synthesis of the hydrotalcite.

In the present invention, the mass of the water is preferably 2-8% of the mass of the neutral red mud, and more preferably 4-8%. The water in the present invention is used to provide the water required for preparing hydrotalcite. It is preferred to control the mass of the water within the above range. If the amount of water is too small, hydrotalcite cannot be prepared; if the amount of water is too high, it is not conducive to the reaction.

In the present invention, the magnesium-containing reagent preferably includes one or more of MgO, MgCO ₃ , Mg(OH) ₂ and magnesium-containing waste, and more preferably one or more of MgO, MgCO ₃ and Mg(OH) _2. In the present invention, the magnesium-containing waste preferably includes magnesium slag and/or magnesium-containing tailings. The present invention has no particular limitation on the source of the magnesium-containing reagent, and commercially available products known to those skilled in the art can be used.

After the mixing is completed, the present invention performs a mechanochemical treatment on the mixed product in a _CO2 atmosphere to obtain an ferromagnesium aluminum carbonate type hydrotalcite material. In the present invention, the mechanochemical treatment is ball milling. The present invention causes lattice defects or distortions in red mud and magnesium-containing reagents through ball milling, and atomic groups and exo-excited electrons are generated on the original surface and the new surface after crushing, thereby activating the solid material red mud and magnesium-containing reagents, improving the activity of solid reactions, and promoting the generation of hydrotalcite materials. In addition, the mechanochemical treatment in the present invention will expose Fe3 ⁺ and Al3 ⁺ on the surface of red mud, and expose Mg2 ⁺ on the surface of magnesium-containing reagents, and then combine with the addition of water and _CO2 , and under the action of mechanochemistry, chemical reactions occur, and finally generate ferromagnesium aluminum carbonate type hydrotalcite materials.

In the present invention, the ball-to-material ratio of the ball mill is preferably 5-10, more preferably 7-10; the rotation speed of the ball mill is preferably 500-700 rpm/min, more preferably 600-700 rpm/min; the time of the ball mill is preferably 120-240 min, more preferably 180-240 min. In the present invention, the ball milling equipment is preferably a planetary ball mill.

In the present invention, the material of the grinding balls used in the ball mill is preferably zirconia; the grinding balls used in the ball mill preferably include grinding balls with diameters ranging from 3 to 15 mm, more preferably grinding balls with diameters of 3m, 8mm and 15mm, with a mass ratio of 3:5:2.

In the present invention, the ball milling method is preferably intermittent ball milling; the intermittent method of the intermittent ball milling is preferably: ball milling for 5 to 10 minutes and stopping for 2 to 4 minutes; the rotation method of the intermittent ball milling is preferably positive and negative alternating rotation. The present invention preferably adopts intermittent ball milling, which has high ball milling efficiency and avoids the high energy generated by continuous ball milling, which is dangerous after being converted into heat energy.

In the present invention, the volume concentration of CO ₂ in the equipment used for mechanochemical treatment is preferably 80 to 100%, more preferably 90 to 100%.

After the ball milling is completed, the present invention preferably dries the ball milled product to obtain the ferromagnesium aluminum carbonate type hydrotalcite material. In the present invention, the drying temperature is preferably 50 to 70° C., more preferably 60 to 70° C.; the drying time is preferably 60 to 120 minutes, more preferably 60 to 100 minutes.

The flow chart of the method for preparing ferromagnesium aluminum carbonate type hydrotalcite material from red mud provided by the present invention is shown in FIG1 , wherein the red mud is first washed and dried to obtain neutral red mud, which is then mixed with a magnesium-containing reagent and water and subjected to mechanochemical treatment in a _CO2 atmosphere to obtain ferromagnesium aluminum carbonate type hydrotalcite material.

The present invention uses red mud as a raw material, first dealkalizes and dries it to obtain neutral red mud, and then mixes it with a magnesium-containing reagent and water and then performs ball milling in a _CO2 atmosphere to obtain an iron-magnesium-aluminum-carbonate-type hydrotalcite material. The present invention causes lattice defects or distortions in the red mud and the magnesium-containing reagent by ball milling, and atomic groups and exo-excited electrons are generated on the original surface and the new surface after crushing, thereby activating the solid material red mud and the magnesium-containing reagent, improving the activity of the solid reaction, and promoting the generation of the hydrotalcite material. The mechanochemical treatment in the present invention exposes Fe3 ⁺ and Al3 ⁺ on the surface of the red mud, and exposes Mg2 ⁺ on the surface of the magnesium-containing reagent. Then, combined with the addition of water and _CO2 , a chemical reaction occurs under the action of mechanochemistry, and finally an iron-magnesium-aluminum-carbonate-type hydrotalcite material is generated. The operation is simple, the process is short, and there is no need to extract aluminum oxide and iron oxide or prepare bimetallic oxides first.

The present invention provides an ferromagnesium aluminum carbonate type hydrotalcite material prepared by the preparation method described in the above technical solution, comprising 10-35wt% of ferromagnesium aluminum carbonate type hydrotalcite and 24-50wt% of SiO ₂ , 5-20wt% of Al ₂ O ₃ , 0.1-18wt% of Al(OH) ₃ , and 0.1-25wt% of Fe ₂ O ₃ . The ferromagnesium aluminum carbonate type hydrotalcite material provided by the present invention has an excellent removal effect on organic pollutants.

The present invention also provides the use of the ferromagnesium aluminum carbonate type hydrotalcite material in the above technical solution in removing organic pollutants. The present invention has no special limitation on the operation of using the ferromagnesium aluminum carbonate type hydrotalcite material in removing organic pollutants, and the technical solution for removing organic pollutants using hydrotalcite materials well known to those skilled in the art can be used.

In the present invention, the organic pollutant preferably includes rhodamine B. In the present invention, when the concentration of the organic pollutant is 100 mg/L, the amount of the ferromagnesium aluminum carbonate type hydrotalcite material relative to the organic pollutant is preferably 1.5 to 3 g/L.

The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

(1) 30 g of red mud was washed with water, and after the washing liquid was measured by pH test paper to be neutral (pH=7.5), it _was filtered and dried at 60°C for 80 min to obtain 22.32 g _of neutral red mud; wherein the mass content of _Fe2O3 in the red mud was 28.74%, the mass content of _Al2O3 was 20.75%, the mass content of MgO was 2.13%, the mass content of _SiO2 was 27.52%, the mass content of Al(OH) ₃ was 15.89%, and the impurity content was 4.97%.

(2) The neutral red mud obtained in step (1) is uniformly mixed with MgO and water, and placed in a planetary ball mill, and _CO2 is introduced for mechanochemical treatment; wherein the mass of MgO is 12% of the mass of the neutral red mud, and the mass of water is 2% of the mass of the neutral red mud; the grinding balls used in the ball mill are made of zirconium oxide, the diameters of the grinding balls are 3 mm, 8 mm and 15 mm, the mass ratio is 3:5:2, the ball-to-material ratio is 7, the rotation speed is 700 rpm/min, and the total ball milling time is 240 min; intermittent ball milling, ball milling for 5 min, stopping for 2 min, and alternating forward and reverse rotation; the volume concentration of _CO2 is 100%; after the ball milling is completed, the sample is dried at 50°C for 120 min to obtain an ferromagnesium aluminum carbonate type hydrotalcite material, containing 23.27wt% of ferromagnesium aluminum carbonate type hydrotalcite and 24.14wt% of _SiO2 , 3.94wt% of Al(OH) ₃ , and _16.70wt % of _Al2O3 , 23.71wt% Fe ₂ O ₃ , 3.39wt% MgO, and 4.85wt% impurities.

The red mud used in this example was subjected to X-ray diffraction, and the obtained XRD pattern is shown in Figure 2. As can be seen from Figure 2, the red mud is mainly composed of _SiO2 , Al(OH) ₃ , _Al2O3 , and _{Fe2O3 .} Since the diffraction peaks of substances _with a content of less than 5% in XRD are relatively weak, the diffraction peaks of magnesium-containing substances are not shown in XRD.

The ferromagnesium aluminum carbonate type hydrotalcite material prepared in this example was subjected to X-ray diffraction, and the obtained XRD pattern was shown in Figure 3. In the figure, LDHs represents ferromagnesium aluminum carbonate type hydrotalcite. As can be seen from Figure 3, compared with the XRD pattern of red mud in Figure 2, the diffraction peaks of SiO ₂ , Al(OH) ₃ , Al ₂ O ₃ , and Fe ₂ O ₃ are significantly reduced, and a new substance LDHs appears, indicating that LDHs are generated in the mechanochemical process of red mud.

Example 2

(1) 30 g of red mud was washed with water, and after the washing liquid was measured by pH test paper to be neutral (pH=6.5), it _was filtered and dried at 60°C for 80 min to obtain 21.19 g _of neutral red mud; wherein the mass content of _Fe2O3 in the red mud was 6.18%, the mass content of _Al2O3 was 28.23%, the mass content of MgO was 0.53%, the mass content of _SiO2 was 57.14%, the mass content of Al(OH) ₃ was 5.35%, and the impurity content was 2.57%.

(2) The neutral red mud obtained in step (1) is mixed with Mg(OH) ₂ and water, and the mixture is placed in a planetary ball mill, and CO ₂ is introduced for mechanochemical treatment; wherein the mass of Mg(OH) ₂ is 18% of the mass of the neutral red mud, and the mass of water is 8% of the mass of the neutral red mud; the grinding balls used in the ball mill are made of zirconium oxide, the diameters of the grinding balls are 3 mm, 8 mm and 15 mm, the mass ratio is 3:5:2, the ball-to-material ratio is 10, the rotation speed is 500 rpm/min, and the total ball milling time is 240 min; intermittent ball milling is performed, the ball milling is performed for 10 min, the stop time is 4 min, and the forward and reverse rotations are alternated; the volume concentration of CO ₂ is 80%; after the ball milling is completed, the sample is dried at 70° C. for 60 min to obtain an ferromagnesium aluminum carbonate type hydrotalcite material, which contains 34.19 wt% of ferromagnesium aluminum carbonate type hydrotalcite and 45.35 wt% of SiO ₂ , 2.99 wt% of Al(OH) ₃ , 7.40 wt% of Al ₂ O ₃ , 3.41 wt% of Fe ₂ O ₃ , 1.96 wt% of MgO, and 4.70 wt% of impurities.

Example 3

(1) 30 g of red mud was washed with water, and after the washing solution was measured to be neutral (pH=7.0) by pH test paper, it _was filtered and dried at 60°C for 80 min to obtain 22.33 g _of neutral red mud; wherein the mass content of _Fe2O3 in the red mud was 13.23%, the mass content of _Al2O3 was 11.48%, the mass content of MgO was 4.87%, the mass content of _SiO2 was 46.12%, the mass content of Al(OH) ₃ was 19.31%, and the impurity content was 4.99%.

(2) The neutral red mud obtained in step (1) is uniformly mixed with MgO and water, placed in a planetary ball mill, and _CO2 is introduced for mechanochemical treatment; wherein the mass of MgO is 5% of the mass of the neutral red mud, and the mass of water is 4% of the mass of the neutral red mud; the grinding balls used in the ball mill are made of zirconium oxide, the diameters of the grinding balls are 3 mm, 8 mm and 15 mm, the mass ratio is 3:5:2, the ball-to-material ratio is 5, the rotation speed is 600 rpm/min, and the total ball milling time is 180 min; intermittent ball milling, ball milling for 8 min, stop for 3 min, and alternate forward and reverse rotation; the volume concentration of _CO2 is 90%; after the ball milling is completed, _the sample is dried at 60°C for 100 min to obtain an ferromagnesium aluminum carbonate type hydrotalcite material, containing 13.22wt% of ferromagnesium aluminum carbonate type hydrotalcite and 42.31wt% of _SiO2 , 15.72wt% of Al(OH) ₃ , and 9.03wt% of _Al2O3 , 11.64wt% Fe ₂ O ₃ , 3.06wt% MgO, and 5.02wt% impurities.

Application Examples

The ferromagnesium aluminum carbonate type hydrotalcite material and red mud prepared in Examples 1 to 3 were respectively added to an aqueous solution containing 100 mg/L of rhodamine B, the amount of ferromagnesium aluminum carbonate type hydrotalcite material and red mud was 1.5 g/L, the reaction was carried out for 45 minutes, and the removal rate of rhodamine B was tested. The test results are shown in Table 1.

Table 1 Removal performance of ferromagnesium aluminum carbonate type hydrotalcite materials and red mud prepared in Examples 1 to 3

blank Red Mud Example 1 Example 2 Example 3 Removal rate 0 19.4% 95.1% 96.9% 97.2%

It can be seen from Table 1 that the ferromagnesium aluminum carbonate type hydrotalcite material provided by the present invention has an excellent removal effect on rhodamine B.

Figure 4 is a diagram showing the removal effect of the ferromagnesium aluminum carbonate type hydrotalcite material and red mud on rhodamine B prepared in Examples 1 to 3 of the present invention. As can be seen from Figure 4, the addition of red mud has basically no removal effect on rhodamine B, but when the ferromagnesium aluminum carbonate type hydrotalcite material prepared by the present invention is added, the removal of rhodamine B is very obvious, the color of rhodamine B disappears, and the water becomes clear and transparent.

It can be seen from the above examples that the preparation method provided by the present invention is simple to operate, has a short process, and does not require the extraction of aluminum oxide and iron oxide or the preparation of bimetallic oxides in advance; the removal rate of rhodamine B by the iron magnesium aluminum carbonate type hydrotalcite material prepared by the present invention can reach 97.2%.

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims (8)

1. A method for preparing ferromagnesium aluminum carbonate type hydrotalcite material from red mud, comprising the following steps: (1) washing, de-alkaliizing and drying the red mud in sequence to obtain neutral red mud; the _red mud contains 5-30% by mass of _Fe2O3 , 10-30% by mass of _{Al2O3 ,} 0.5-5% by mass of MgO, 25-60% by mass of _SiO2 and 5-20% by mass of Al(OH) ₃ ; (2) The neutral red mud obtained in step (1) is mixed with a magnesium-containing reagent and water, and then subjected to a mechanochemical treatment in a _CO2 atmosphere to obtain an ferromagnesium-aluminum carbonate-type hydrotalcite material; the mechanochemical treatment is ball milling; the mass of the magnesium-containing reagent is 5-20% of the mass of the neutral red mud, and the mass of the water is 2-8% of the mass of the neutral red mud; the grinding balls used in the ball milling are made of zirconium oxide. 2. The method according to claim 1, characterized in that the end point of the water washing and de-alkali treatment in step (1) is that the pH of the washing solution is 6.5-7.5. 3. The method according to claim 1, characterized in that the drying temperature in step (1) is 50-80°C and the drying time is 30-120 min. 4. The method according to claim 1, characterized in that the magnesium-containing reagent in step (2) comprises one or more of MgO, _MgCO3 , Mg(OH) ₂ and magnesium-containing waste. 5. The method according to claim 1, characterized in that the ball-to-material ratio of the ball milling in the step (2) is 5-10, the rotation speed of the ball milling is 500-700 rpm/min, and the ball milling time is 120-240 min. 6. The method according to claim 1 or 5, characterized in that the grinding balls used in the ball milling in step (2) include grinding balls with diameters ranging from 3 to 15 mm. 7. The ferromagnesium aluminum carbonate type hydrotalcite material prepared by the method according to any one of claims 1 to ₆ , comprising 10-35wt% of ferromagnesium aluminum carbonate type hydrotalcite, 24-50wt% of _SiO2 , 5-20wt% _{of Al2O3} , 0.1-18wt% of Al(OH) ₃ , and 0.1-25wt% of _Fe2O3 . 8. Use of the ferromagnesium aluminum carbonate type hydrotalcite material according to claim 7 in removing organic pollutants.