Method for extracting chemical elements from red soil

Abstract

The present application discloses a method for extracting chemical elements from red soil, relates to the field of mineral technology, and solves the problems in the prior art that red soil cannot be fully utilized, red desertification is formed, and red soil has many minerals and is highly acidic. The method comprises: taking a portion of a red soil sample, adding an acidic solution, mixing and roasting, adding water after cooling to room temperature, stirring, condensing and refluxing, naturally cooling, filtering and drying to obtain a first solid and a first filtrate; adding hydrogen peroxide to the first filtrate and adjusting the pH value to 3-4, filtering to obtain a second filter residue and a second filtrate, and calcining the second filter residue to obtain a second solid; adding ammonia water to the second filtrate to adjust the pH value to 9, and introducing CO2 gas until the pH value is between 7 and 8, filtering to obtain a third filter residue and a third filtrate, calcining the third filter residue to obtain a third solid, and evaporating to obtain a fourth solid. The purpose of having a high extraction rate of chemical elements in the red soil is achieved, and the reaction is simple and the production cost is low.

Description

Technical Field

[0001] The present application relates to the field of mineral technology, and in particular to a method for extracting chemical elements from red soil. Background Art

[0002] In the vast southern Fujian region south of the Yangtze River in my country, due to the high temperature and rainy climate conditions, a red soil has been formed. This soil has low organic matter content, high iron and aluminum content, strong acidity, and heavy soil texture. It is not suitable for the cultivation of various crops and is therefore relatively poor.

[0003] Current research on laterite soils primarily focuses on improving the soil's quality by adding organic fertilizers and slaked lime. This soil improvement method has resulted in the planting of economically viable trees such as tea, oil-tea camellia, fir, and masson pine, which thrive in acidic soils. This has helped conserve soil and water resources while also improving economic returns. However, due to a large population and limited land, overexploitation of the laterite soils, combined with their inherent characteristics, has resulted in low productivity, severe soil erosion, and severe degradation in many areas, resulting in "red desertification." Summary of the Invention

[0004] The embodiments of the present application provide a method for extracting chemical elements from red soil, thereby solving the problems in the prior art of insufficient utilization of red soil, resulting in red desertification, and the high mineral content and strong acidity of red soil. The method achieves a high extraction rate of chemical elements from red soil, simple reaction, low risk, low production cost, and safety and environmental protection.

[0005] An embodiment of the present invention provides a method for extracting chemical elements from red soil, the method comprising:

[0006] Taking a portion of a red soil sample, adding an acidic solution, mixing, and roasting, adding water, stirring, condensing, and refluxing after cooling to room temperature, and filtering and drying after natural cooling to obtain a first solid and a first filtrate;

[0007] adding hydrogen peroxide to the first filtrate and adjusting the pH value to 3-4, filtering the first filtrate to obtain a second filter residue and a second filtrate, and calcining the second filter residue to obtain a second solid;

[0008] Ammonia water is added to the second filtrate to adjust the pH to 9, and CO2 gas is introduced until the pH value is between 7 and 8, and the third filter residue and the third filtrate are obtained by filtration, and the third filter residue is calcined to obtain a third solid;

[0009] The third filtrate was evaporated to dryness to obtain a fourth solid.

[0010] In a possible implementation, the acidic solution includes a concentrated sulfuric acid solution with a concentration of 98%.

[0011] In a possible implementation, adding hydrogen peroxide to the first filtrate and adjusting the pH value to 3-4 includes: adding 30 wt.% hydrogen peroxide solution to the first filtrate, and adding ammonia water to adjust the pH value to 3-4.

[0012] In a possible implementation, the adding of the acidic solution, mixing, and calcining includes: adding the acidic solution, mixing, and calcining at a temperature between 250° C. and 300° C. for 2 hours.

[0013] In a possible implementation, the adding of water, stirring, and condensing and refluxing includes: after adding water, maintaining the temperature between 80° C. and 100° C., stirring, and condensing and refluxing for 2 h to 4 h.

[0014] In a possible implementation, calcining the second filter residue to obtain the second solid includes: calcining the second filter residue at 300° C. to 500° C. for 2 to 4 hours to obtain the second solid.

[0015] In a possible implementation, calcining the third filter residue to obtain the third solid includes: calcining the third filter residue at 300° C. to 500° C. for 2 to 4 hours to obtain the third solid.

[0016] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0017] The embodiment of the present invention adopts a method for extracting chemical elements from red soil, which includes: taking a portion of the red soil sample, adding an acidic solution, mixing and roasting, cooling to room temperature, adding water, stirring, condensing and refluxing, cooling naturally, filtering and drying to obtain a first solid and a first filtrate; adding hydrogen peroxide to the first filtrate and adjusting the pH value to 3-4, filtering the first filtrate to obtain a second filter residue and a second filtrate, and calcining the second filter residue to obtain a second solid; adding ammonia water to the second filtrate to adjust the pH to 9, and passing CO2 gas until the pH value is between 7 and 8, filtering to obtain a third filter residue and a third filtrate, calcining the third filter residue to obtain a third solid; and evaporating the third filtrate to obtain a fourth solid. The method proposed in this application has a simple reaction system, the reagents used are also easily available, and it can be prepared through a cheap and readily available reaction. The target product is synthesized using concentrated acid and ammonia water as raw materials, without the need for any additional chemical reagents, the reaction temperature is moderate, and no additional stirring is required after the raw materials are mixed evenly. The production cost is low, and no three wastes are discharged during the preparation process. The method effectively solves the problem in the prior art that red soil cannot be fully utilized and red desertification is formed, and achieves the purpose of high extraction rate of chemical elements in red soil, simple reaction and low risk, and has low production cost, safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments of the present invention or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is the full XPS spectrum of the red soil provided in the examples of this application;

[0020] Figure 2 C 1s spectrum of red soil provided in the examples of this application;

[0021] Figure 3 Al 2p spectrum of red soil provided in the examples of this application;

[0022] Figure 4 The Si 2p spectrum of the laterite soil provided in the examples of this application;

[0023] Figure 5 Fe 2p spectrum of red soil provided in the examples of this application;

[0024] Figure 6 O 1s spectrum of red soil provided in the examples of this application;

[0025] Figure 7 The X-ray diffraction spectrum of the laterite soil provided in the examples of this application;

[0026] Figure 8 This is the full XPS spectrum of the first solid provided in the examples of this application;

[0027] Figure 9 C 1s spectrum of the first solid provided in the examples of the present application;

[0028] Figure 10 The Si 2p spectrum of the first solid provided in the embodiment of the present application;

[0029] Figure 11 The S 2p spectrum of the first solid provided in the examples of the present application;

[0030] Figure 12 N 1s spectrum of the first solid provided in the examples of the present application;

[0031] Figure 13 This is the O 1s spectrum of the first solid provided in the examples of the present application;

[0032] Figure 14An X-ray diffraction spectrum of the first solid provided in an embodiment of the present application;

[0033] Figure 15 This is the full XPS spectrum of the second solid provided in the examples of the present application;

[0034] Figure 16 C 1s spectrum of the second solid provided in the examples of the present application;

[0035] Figure 17 The Si 2p spectrum of the second solid provided in the embodiment of the present application;

[0036] Figure 18 This is the O 1s spectrum of the second solid provided in the examples of the present application;

[0037] Figure 19 An X-ray diffraction spectrum of the second solid provided in an embodiment of the present application;

[0038] Figure 20 This is the full XPS spectrum of the third solid provided in the examples of this application;

[0039] Figure 21 C 1s spectrum of the third solid provided in the examples of the present application;

[0040] Figure 22 Si 2p spectrum of the third solid provided in the examples of this application;

[0041] Figure 23 This is the O 1s spectrum of the third solid provided in the examples of the present application;

[0042] Figure 24 An X-ray diffraction spectrum of the third solid provided in an embodiment of the present application;

[0043] Figure 25 This is the full XPS spectrum of the fourth solid provided in the examples of this application;

[0044] Figure 26 This is the C 1s spectrum of the fourth solid provided in the examples of the present application;

[0045] Figure 27 This is the O 1s spectrum of the fourth solid provided in the examples of the present application. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making any creative efforts are within the scope of protection of the present invention.

[0047] In the vast southern Fujian region south of the Yangtze River in my country, a type of red soil has been developed due to the high temperature and high rainfall conditions. This soil has a low organic matter content, high iron and aluminum content, strong acidity, and heavy clay texture, making it unsuitable for growing a variety of crops and therefore relatively poor. Current research on red soil mainly focuses on improving the red soil by adding organic fertilizers and supplementing slaked lime to the red soil. Although this method has planted economic trees such as tea trees, oil-tea camellia, fir, and masson pine that are suitable for growing in acidic soil, it has maintained water and soil while improving economic benefits. However, due to the large population and limited land, the over-exploitation of the soil, and the characteristics of the soil itself, the soil productivity in the red soil area is low, soil and water loss are serious, and it has seriously degraded in many areas, forming "red desertification". In view of this, the present application proposes a method for extracting chemical elements from red soil, which includes the following steps S101 to S104.

[0048] S101, taking a portion of the red soil sample, adding an acidic solution, mixing and roasting, adding water after cooling to room temperature, stirring and condensing and refluxing, naturally cooling, filtering and drying to obtain a first solid and a first filtrate.

[0049] S102, adding hydrogen peroxide to the first filtrate and adjusting the pH value to 3-4, filtering the first filtrate to obtain a second filter residue and a second filtrate, and calcining the second filter residue to obtain a second solid.

[0050] S103, adding ammonia water to the second filtrate to adjust the pH to 9, and introducing CO2 gas until the pH value is between 7 and 8, filtering to obtain a third filter residue and a third filtrate, and calcining the third filter residue to obtain a third solid.

[0051] S104, evaporating the third filtrate to dryness to obtain a fourth solid.

[0052] In a specific embodiment of the present application, in step S101, 20g to 30g of red clay sample is mixed with 98% concentrated sulfuric acid. The amount of concentrated sulfuric acid added should be excessive, and the mixture is placed in a muffle furnace for roasting until the liquid evaporates to dryness and then naturally cooled to room temperature. In practical applications, concentrated acid solution is easily available, and the temperature is controlled between 250°C and 300°C during roasting. The roasting time is generally 2 hours, and the roasting temperature is also easily achievable. The roasting time is directly related to the amount of sample and the amount of concentrated acid. Experiments have shown that at the above-mentioned temperature, the best crystal form can be obtained by removing impurities.

[0053] In step S102, hydrogen peroxide is added to the first filtrate and the pH is adjusted to 3-4, which includes adding a 30 wt.% hydrogen peroxide solution to the first filtrate and then adding aqueous ammonia to adjust the pH to 3-4. The addition of excess hydrogen peroxide precipitates the acidic oxides in the first filtrate, and the addition of aqueous ammonia precipitates the hydroxide metal base in the first filtrate.

[0054] In step S101, water is added, stirred, and condensed under reflux, including: after adding water, the temperature is maintained between 80°C and 100°C, stirred, and condensed under reflux for 2 to 4 hours. In a specific embodiment of the present application, the stirring and condensing reflux is performed between 80°C and 100°C. Of course, the solution can be condensed and refluxed as long as the temperature is controlled within the range where condensed water appears.

[0055] In step S102, the second filter residue is calcined to obtain a second solid, comprising calcining the second filter residue at a temperature between 300°C and 500°C for 2 to 4 hours to obtain the second solid. In step S103, the third filter residue is calcined to obtain a third solid, comprising calcining the third filter residue at a temperature between 300°C and 500°C for 2 to 4 hours to obtain the third solid. In both steps, calcining at a temperature between 300°C and 500°C can produce a better crystalline form.

[0056] The following are the basic steps for operating according to the method provided in this application in an example of this application.

[0057] 1. Mix 20 g of red clay sample with 20 mL of concentrated sulfuric acid (98%) and place it in a muffle furnace. After calcining at 280°C for 2 hours, cool it naturally to room temperature, add 200 mL of water, stir it at 80°C for 2 hours, condense and reflux it, cool it naturally, filter and dry it to obtain the first solid, and retain the first filtrate.

[0058] 2. Slowly add 5 mL of 30 wt.% hydrogen peroxide to the first filtrate and adjust the pH of the mixed solution to between 3 and 4 with aqueous ammonia. The second filter residue collected by filtration is calcined in a muffle furnace at 400°C for 2 hours to obtain a second solid. The second filtrate is retained.

[0059] 3. Ammonia water was added to the second filtrate to adjust its pH to 9. CO2 gas was then introduced into the solution until the pH was between 7 and 8. The mixture was filtered to obtain a third residue and a third filtrate. The third residue was calcined in a muffle furnace at 400°C for 2 hours to obtain a third solid. The third filtrate was retained.

[0060] 4. Evaporate the third filtrate to dryness to obtain the fourth solid.

[0061] Table 1 shows the X-ray photoelectron spectroscopy (XPS) element binding energy and chemical composition of the red soil and various samples in the implementation cases. From Table 1, the experimental molecular formula of the red soil can be obtained as follows:

[0062] O 40.53 C 38.02 F 0.41 Y 0.87 Si 10.67 Al 9.30 Fe 0.20 ; Molecular weight: 1752.0462.

[0063] Among them, the mass percentages are: Si%=17.10%; Al%=14.32%; Fe%=0.63%; Y%=4.41%.

[0064] Table 1 Element binding energy and chemical composition of red soil samples

[0065]

[0066] a Binding energy (eV), the values in parentheses are atomic percentages (at%).

[0067] Table 2 Element binding energy and chemical composition of the first solid

[0068]

[0069] a Binding energy (eV), the values in parentheses are atomic percentages (at%).

[0070] Table 3 Element binding energy and chemical composition of the second solid

[0071]

[0072] a Binding energy (eV), the values in parentheses are atomic percentages (at%).

[0073] Table 4 Element binding energy and chemical composition of the third solid

[0074]

[0075] a Binding energy (eV), the values in parentheses are atomic percentages (at%).

[0076] Table 5 Element binding energy and chemical composition of the fourth solid

[0077]

[0078] a Binding energy (eV), the values in parentheses are atomic percentages (at%).

[0079] Depend on Figure 1 It can be seen that laterite soil contains all the elements in Table 1, and no other impurity elements. Figure 2 It can be seen that the peak of binding energy at 284.6 eV represents saturated carbon (such as alkyl C, hybridization mode is sp 3 The peak with a binding energy of 285.8 eV represents carbon in CO bonds, and the peak with a binding energy of 288.6 eV represents carbon in carboxyl groups. The molar ratio of these three is saturated carbon: carbon in CO bonds: carbon in carboxyl groups = 56.56:30.15:13.29. This indicates that the organic components in red soil are small organic molecules containing C, N, and O.

[0080] Depend on Figure 3 It can be seen that the Al 2p peak of the red soil appears at 74.4eV, which is lower than the peak of Al in Al2O3 (74.9eV) and higher than the peak of elemental Al (72.6eV). Therefore, the Al in Red Soil No. 1 should be Al 3+ .

[0081] Depend on Figure 4 It can be seen that the Si 2p peak of the red soil appears at 102.7 eV, while there is no peak at 99-100 eV, indicating that the Si in the red soil all comes from SiO2, and Red Soil No. 1 does not contain elemental silicon.

[0082] Depend on Figure 5 It can be seen that the peak of binding energy at 725.0 eV represents Fe 2p 1 / 2 photoelectrons, and the peak at 712.0 eV represents Fe 2p 3 / 2 Photoelectrons, the above peak positions all represent Fe 3+ , that is, the Fe element in red soil is Fe 3+ There is no Fe in red soil. 2+ The existence of Fe 2+ Fe 2p 1 / 2 The photoelectron peaks at around 721.0 eV, while Fe 2p 3 / 2 The photoelectron peaks at around 708.0 eV.

[0083] Depend on Figure 6 It can be seen that the broad peak with a binding energy of 531.7 eV represents the oxygen on Al2O3 or other aluminate-containing red soil No. 1, the peak at 532.0 eV represents the oxygen on SiO2 in the red soil, and the peak at 532.4 eV represents the oxygen on organic matter.

[0084] Depend on Figure 7 It can be seen that in addition to quartz, laterite soil also contains Al2O3. No other phases were found.

[0085] As can be seen from Table 2, the experimental molecular formula of the first solid is: 39.70 C 31.18 N 5.54 S 8.82 Si 14.76 The molecular weight is 1784.6648. The mass percentage is SiO2% = 49.69%. The C and N elements contained in the first solid are derived from the organic matter contained in the red soil itself; the S element contained in the first solid is derived from the residue after the sulfuric acid reaction in the previous step. Figure 8 It can be seen that, except for the elements in Table 2, the first solid does not contain other impurity elements.

[0086] Depend on Figure 9 It can be seen that the peak of binding energy at 284.4 eV represents unsaturated carbon (such as double bond C, hybridization mode is sp 2 ), the peak with binding energy at 285.0 eV represents saturated carbon (such as alkyl C, hybridization mode is sp 3 ), the peak with a binding energy of 286.3 eV represents carbon atoms in C-N bonds, and the peak with a binding energy of 288.7 eV represents carbon atoms in carboxyl groups. The molar ratio of these four is: unsaturated carbon: saturated carbon: carbon atoms in C-O bonds: carbon atoms in carboxyl groups = 24.52: 41.32: 22.77: 11.39. This indicates that the organic components contained in the first solid are small organic molecules containing C, N, and O. (Since there are no peaks after 290 eV, this organic component does not contain polymeric carbon chains, such as polyethylene or polypropylene.) Overall, the XPS carbon spectrum of the first solid indicates the presence of organic matter in the red soil, in the form of small organic molecules.

[0087] Depend on Figure 10 It can be seen that the Si 2p peak of the first solid appears at 103.2 eV, while there is no peak at 99-100 eV, indicating that the Si in the first solid all comes from SiO2 and the first solid does not contain silicon element.

[0088] Depend on Figure 11 It can be seen that the peak at 169.4 eV represents the S 2p1 / 2 photoelectrons of the first solid, and the peak at 168.2 eV represents the S 2p 3 / 2 Photoelectrons. According to the first solid S 2p 3 / 2 The peak position of the photoelectron indicates that the S in sample 1 is in the form of SO4 2- Form exists.

[0089] Depend on Figure 12 It can be seen that the N1s spectrum of the first solid contains only one component: the peak at a binding energy of 401.4 eV represents the -NH- group, which originates from the organic components in the first solid. In addition, the first solid contains almost no NO 3- .

[0090] Depend on Figure 13 It can be seen that the broad peak with a binding energy of 531.5 eV represents the oxygen on SO42- in the first solid, and the peak at 532.4 eV represents the oxygen on SiO2 in the first solid. In addition, the first solid does not contain any metal oxide (because no O1s peak is found below 530.0 eV).

[0091] Depend on Figure 14 As can be seen from Table 2, the main component of the first solid is quartz (SiO2), and it also contains a small amount of ammonium sulfate (NH4(HSO4)(H2SO4)).

[0092] As can be seen from Table 3: the experimental molecular formula of the second solid is: 40.51 C 27.40 N 1.21 S 4.06 Si 26.81 The molecular weight is 1877.4426. The mass percentage is SiO2=85.68%. The carbon and nitrogen elements in the second solid are derived from the organic matter in Red Soil No. 1 itself. The sulfur element in the second solid is the residue from the sulfuric acid reaction in the previous step.

[0093] Depend on Figure 15 It can be seen that, except for the elements in Table 3, the second solid does not contain other impurity elements.

[0094] Depend on Figure 16 It can be seen that the peak at 284.6 eV represents unsaturated carbon (such as double bond C, hybridization mode is sp 2 ), the peak with binding energy at 284.9 eV represents saturated carbon (such as alkyl C, hybridization mode is sp 3 ), the peak at 286.3 eV represents carbon atoms in CO bonds, and the peak at 288.7 eV represents carbon atoms in carboxyl groups. The molar ratio of these four is: unsaturated carbon: saturated carbon: carbon atoms in CO bonds: carbon atoms in carboxyl groups = 18.72: 50.09: 21.62: 9.57. This indicates that the organic components contained in the second solid are small organic molecules containing C, N, and O. (Since there are no peaks after 290 eV, this organic component does not contain polymeric carbon chains, such as polyethylene and polypropylene.) Overall, the XPS carbon spectrum of the second solid indicates the presence of organic matter in the red soil, in the form of small organic molecules.

[0095] Depend on Figure 17 It can be seen that the Si 2p peak of the second solid appears at 102.6 eV, while there is no peak at 99-100 eV, indicating that the Si in the second solid all comes from SiO2 and the second solid does not contain silicon element.

[0096] Depend on Figure 18It can be seen that the peak with a binding energy of 532.6 eV represents oxygen on SiO2 in the second solid. In addition, the second solid does not contain any metal oxide (because no O1s peak is found below 530.0 eV).

[0097] Depend on Figure 19 ,Combined with Table 3, it can be seen that the main component of the second solid is quartz (SiO2), and it may also contain a small amount of iron sulfate (FeFe2(SO4)4(H2O)2), and may also contain other sulfates.

[0098] As shown in Table 4, the experimental molecular formula of the third solid is: 34.50 C 41.33 N 11.23 S1 0.48 Si 2.46 The molecular weight is 1610.7958. The mass percentage is SiO2% = 9.16%. The carbon and nitrogen contained in solid C3 originate from the organic matter in Red Soil No. 1. The sulfur contained in the third solid originates from the sulfuric acid in the previous step.

[0099] Depend on Figure 20 It can be seen that, except for the elements in Table 4, the third solid does not contain other impurity elements.

[0100] Depend on Figure 21 As can be seen, the peak at 284.8 eV represents saturated carbon (e.g., alkyl carbon, sp3 hybridization), the peak at 286.3 eV represents carbon in a CO bond, and the peak at 288.7 eV represents carbon in a carboxyl group. The molar ratio of these three is 59.24:29.10:11.65. This indicates that the organic components contained in the third solid are small organic molecules containing C, N, and O. (Since there are no peaks after 290 eV, this organic component does not contain polymeric carbon chains, such as polyethylene and polypropylene.) Overall, the XPS carbon spectrum of the third solid indicates the presence of organic matter in the red soil, in the form of small organic molecules.

[0101] Depend on Figure 22 It can be seen that the Si 2p peak of the third solid appears at 102.5 eV, while there is no peak at 99-100 eV, indicating that the Si in the third solid all comes from SiO2, and sample one does not contain silicon element.

[0102] Depend on Figure 23 It can be seen that the peak of binding energy at 531.7eV represents SO4 2- The peak at 532.7 eV represents the oxygen on SiO2 in the third solid (including oxygen on organic matter). In addition, the third solid does not contain any metal oxides (because no O1s peak is found below 530.0 eV).

[0103] Depend on Figure 24 ,Combined with Table 4, it can be seen that the main component of the third solid is ammonium sulfate ((NH4)2SO4) with high purity, and no other by-products are found.

[0104] As can be seen from Table 5, the experimental molecular formula of the fourth solid is: 47.30 C 18.69 N 16.30 S 17.71 The molecular weight is 1777.4125, and the element molar ratio is S:O = 1:2.67. The fourth solid may contain sulfate.

[0105] Depend on Figure 25 It can be seen that, except for the elements in Table 5, the fourth solid does not contain other impurity elements.

[0106] Depend on Figure 26 It can be seen that the peak of binding energy at 284.7 eV represents saturated carbon (such as alkyl C, hybridization mode is sp 3 The peak at 286.2 eV represents carbon atoms in CO bonds, and the peak at 288.7 eV represents carbon atoms in carboxyl groups. The molar ratio of these three is saturated carbon: carbon atoms in CO bonds: carbon atoms in carboxyl groups = 53.06:37.73:9.21. This indicates that the organic components contained in the fourth solid are small organic molecules containing C, N, and O. (Since there are no peaks after 290 eV, this organic component does not contain polymeric carbon chains, such as polyethylene and polypropylene.) Overall, the XPS carbon spectrum of the fourth solid indicates the presence of organic matter in the red soil, in the form of small organic molecules.

[0107] Depend on Figure 27 It can be seen that the peak of binding energy at 531.4eV represents SO4 2- The peak at 532.4 eV represents oxygen on the organic matter in the fourth solid. Furthermore, the fourth solid contains no metal oxides (as no O1s peak is observed below 530.0 eV). Overall, the primary component of the fourth solid is likely ammonium sulfate, with other impurities present.

[0108] Compared with the prior art, the present invention has the following beneficial effects: (1) The reaction system is safe and has high purity: the method for extracting valuable chemical elements from red soil provided by the present invention has a high extraction rate, and the reaction system is simple and low in risk; (2) Low production cost: the method provided by the present invention can synthesize the target product by using concentrated acid and industrial ammonia water as raw materials through a cheap and readily available reaction, without the need to add any additional chemical reagents, the reaction temperature is moderate, and no additional stirring is required after the raw materials are evenly mixed; (3) Low hazard, safe and environmentally friendly: the method provided by the present invention is used to extract valuable chemical elements from red soil. Since the reaction uses concentrated sulfuric acid and industrial ammonia water as raw materials, no other chemicals are added, the reaction temperature is moderate, and no three wastes are discharged during the preparation process.

[0109] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for extracting chemical elements from red soil, characterized in that: include: 20-30 g of a laterite soil sample is added to a 98% concentrated sulfuric acid solution, mixed, and calcined at 250-300° C. for two hours. After cooling to room temperature, water is added, the mixture is stirred at 80-100° C., and refluxed under condensation for 2-4 hours. After natural cooling, the mixture is filtered and dried to obtain a first solid and a first filtrate, wherein the first solid comprises SiO2 and ammonium sulfate. adding a 30 wt.% hydrogen peroxide solution to the first filtrate to precipitate acidic oxides, and adding aqueous ammonia to adjust the pH to 3-4 to precipitate hydroxide metal bases, filtering the first filtrate to obtain a second filter residue and a second filtrate, and calcining the second filter residue at 300° C. to 500° C. for 2 h to 4 h to obtain a second solid; the second solid comprises SiO2 and ferric sulfate; Ammonia water is added to the second filtrate to adjust the pH to 9, and CO2 gas is introduced until the pH value is between 7 and 8, and the third filter residue and the third filtrate are obtained by suction filtration, and the third filter residue is calcined at 300° C. to 500° C. for 2 h to 4 h to obtain a third solid, wherein the third solid includes ammonium sulfate; The third filtrate is evaporated to dryness to obtain a fourth solid, which includes ammonium sulfate.

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