Low-cost alkali-removing and fertilizing soil improvement agent for red mud soil and application thereof
By mixing the leachate and leaching residue from acid-treated high-phytic acid agricultural waste with red mud, the problems of high cost and secondary pollution of red mud amendments were solved, achieving rapid dealkalization and increased nutrient content of red mud, thus promoting soil improvement of red mud.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CENT SOUTH UNIV
- Filing Date
- 2023-08-30
- Publication Date
- 2026-06-12
Smart Images
Figure CN117165298B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of harmless treatment of bulk solid waste and environmental protection technology, specifically to a low-cost red mud soil conditioner for dealkalization and fertilization and its application. Background Technology
[0002] Red mud is a highly alkaline waste residue discharged during the alumina industrial production process. Its comprehensive utilization rate is less than 3%, and it is mainly disposed of by dry stockpiling. This not only occupies a large amount of land resources, but may also lead to serious ecological and environmental problems such as air pollution, surface water and groundwater pollution in the surrounding areas.
[0003] Red mud soilification is one of the most effective methods for large-scale waste disposal. Commonly used red mud substrate amendments include gypsum, inorganic acids, organic acids, acidic flue gas, and biomass. However, substances like calcium in gypsum... 2+ Able to bind with Na in the base + The displacement reaction produces a large amount of salt, causing surface blooming; neutralization with inorganic acids is costly and dissolves minerals, further reducing porosity; while organic acids can promote the formation of large aggregates, their alkalinity regulation is poor; the main components of acidic flue gas are carbon dioxide and sulfur dioxide, posing a potential secondary pollution problem; using biomass such as straw and rice straw in conjunction with manure as a conditioner is the most economical and effective method, but biomass fermentation and fertilization time is long, and most of the inorganic phosphorus in the manure will be converted into hydroxyapatite or adsorbed by minerals, making it difficult for microorganisms / plants to utilize, resulting in a large loss of phosphate fertilizer. Therefore, there is an urgent need in this field for a simple and economical multifunctional conditioner for the remediation of red mud.
[0004] Therefore, providing a low-cost red mud soil conditioner for dealkalization and fertilization and its application is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] The purpose of this invention is to propose a low-cost red mud soil conditioner for dealkalization and fertilization, and its application. This invention utilizes agricultural solid waste with high phytic acid content, which is acid-leached to obtain a phytic acid-rich leachate, enabling rapid, efficient, and continuous dealkalization of red mud. Phytic acid contains abundant phosphorus and other nutrients; under the action of specific phytases from microorganisms, it hydrolyzes to generate long-lasting carbon and phosphorus sources that can be utilized by plant roots, effectively increasing the nutrient content of the red mud. Phytic acid contains a large number of organic functional groups, reducing the migration risk of heavy metals in the red mud. Simultaneously, the leachate residue contains a large amount of organic matter, rapidly increasing the fertility of the red mud. After acid treatment, the leachate residue is more easily decomposed and utilized by microorganisms, improving the microbial activity in the red mud and accelerating the cycling of nutrients. The leachate residue can significantly reduce the bulk density of the red mud, improve its porosity and water-holding capacity, which is beneficial to plant growth. Furthermore, the process is simple, effective, green, and free of secondary pollution.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A red mud soil amendment includes the following leachate residue and leachate;
[0008] The leaching residue and leachate are obtained by solid-liquid separation of agricultural solid waste with high phytic acid content after acid treatment.
[0009] Phytic acid is a cyclic compound containing various active organic functional groups. It is strongly acidic and has a strong metal chelating ability. Phytic acid is widely found in plants and is the main form in which phosphorus exists. More than 5 billion tons of agricultural solid waste are generated annually, originating from a wide range of dispersed sources, making resource utilization difficult. Most of it is disposed of through incineration or stockpiling. In the past, materials such as rice bran and wheat bran, rich in nutrients like carbon, nitrogen, and phosphorus, as well as trace elements like calcium, magnesium, and iron, were used as livestock feed. However, with the development of food science, researchers have discovered that the high phytic acid content in rice bran can form chelates with trace elements in animals that are difficult to absorb, severely hindering animal growth and development. In recent years, the proportion of rice bran in livestock feed has gradually decreased, further exacerbating the difficulty of resource utilization.
[0010] This invention fully utilizes the unique physiological functions and chemical properties of phytic acid. Through acid leaching, it uses agricultural solid waste leachate with high phytic acid content and leachate residue to simultaneously address the salinity, porosity, and nutrient deficiency of red mud, achieving low-cost dealkalization of red mud, accelerating the soil formation process of red mud, and providing plant growth substrate for the ecological restoration of red mud dumps and other mines. It has significant social benefits and broad market prospects.
[0011] Preferably, the agricultural solid waste with high phytic acid content is at least one of rice bran, wheat bran, and oat bran.
[0012] The rice bran, wheat bran, and oat bran used in this invention are agricultural solid wastes generated from grain refining, with phytic acid contents of 6.5-8.7%, 1.1-3.9%, and 0.21-0.73%, respectively. These are agricultural solid wastes with relatively high phytic acid content that are currently known.
[0013] Preferably, the agricultural solid waste with high phytic acid content is dried at 60-75℃ for 48 hours and passed through a 40-80 mesh sieve before acid treatment.
[0014] Preferably, the agricultural solid waste with high phytic acid content is rice bran or wheat bran;
[0015] Preferably, the mass ratio of the agricultural solid waste with high phytic acid content to red mud is (1-10):100;
[0016] Preferably, the acid treatment uses any one of the dilute acid solutions with a pH of 2-6;
[0017] The mass ratio of the acid to the agricultural solid waste with high phytic acid content is 100:(10-35); preferably 100:(20-25), and more preferably 100:25;
[0018] The acid treatment time is 0.5-3 hours, preferably 1.5-2.0 hours, and more preferably 1.5 hours.
[0019] This invention is the first to use agricultural solid waste with high phytic acid content as biomass for red mud matrix improvement. It specifically improves the commonly used phytic acid extraction method, acid leaching, by combining acid leaching solution and leaching residue for dealkalization, which rapidly reduces the content of free and bound alkali in red mud and accelerates the red mud soil formation process. The leaching residue can improve the structure of red mud aggregates and, together with the phytate generated by the neutralization reaction, serve as a long-lasting nutrient for exogenous microorganisms and plant growth, continuously improving the adaptability of the soil and obtaining soil-based red mud that can support plant growth.
[0020] Preferably, the dilute acid solution is any one of sulfuric acid, hydrochloric acid, nitric acid, and phytic acid.
[0021] Preferably, the dilute acid solution used is sulfuric acid or hydrochloric acid with a pH of 3-4.
[0022] Further preferred, the dilute acid solution used is sulfuric acid with pH=4.
[0023] The application of the amendments described above in the red mud soil transformation.
[0024] Preferably, the method of using the modifier is as follows:
[0025] (1) After mixing and reacting the red mud and leachate, the precipitate obtained is the dealkalized red mud;
[0026] (2) After mixing the dealkalized red mud with the leaching residue and piling it up for fertilization, soil-based red mud is obtained.
[0027] Preferably, the mass ratio of the red mud to the leachate in step (1) is 100:70, and the reaction time is 60 min.
[0028] Preferably, the red mud in step (1) is red mud discharged after pressure filtration or red mud that has been stockpiled and passed through a 40-80 mesh sieve.
[0029] Preferably, the composting time in step (2) is 7-30 days, and the composting temperature is controlled at 15-35℃.
[0030] The application of red mud after soil treatment as described above in planting.
[0031] Agricultural solid wastes such as rice bran, wheat bran, and oat bran are rich in phytic acid, making them a primary raw material for industrial phytic acid extraction. Phytic acid contains a high density of negatively charged phosphate groups, making it an important green organophosphate additive widely used in food and pharmaceutical fields. Phytic acid possesses 12 dissociable hydrogen ions, exhibiting strong acidity, which can reduce the alkalinity of red mud and react with Ca... 2+ Fe 2+ Mg 2+ Al 3+ The isocations form stable chelates, which, together with the leaching residue after acid leaching, provide nutrients for exogenous microorganisms and can effectively promote the establishment of grasses such as ryegrass, crested wheatgrass, and tall fescue.
[0032] Compared with the prior art, the present invention has the following beneficial effects:
[0033] (1) The agricultural solid waste with high phytic acid content provided by the present invention contains not only long-chain carbon sources such as crude fiber and crude protein, but also relatively high phytic acid. Phytic acid is used for alkaline neutralization of red mud, which is green and has no secondary pollution.
[0034] (2) The acid treatment process provided by the present invention is simple and convenient, the required acid solution is inexpensive, widely available and in small quantities, the treatment process has low energy consumption and short cycle, and is easy to achieve large-scale production.
[0035] (3) In this invention, the phytic acid obtained by acid treatment will preferentially react with Fe in the red mud, depending on the stability of the chelate. 3+ Al 3+ As the reaction produces a precipitate, the conductivity of the solution decreases. At lower ion concentrations, free Ca... 2+ Able to better interact with Na + Calcium-sodium exchange occurs, reducing the content of bound base.
[0036] (4) The phytic acid obtained by acid treatment in this invention and the phytate formed by the cation can be hydrolyzed by specific phytase secreted by microorganisms to generate small molecule inositol and phosphate that can be utilized by plant roots, thereby continuously improving the adaptability of red mud.
[0037] (5) The agricultural solid waste provided by the present invention contains a large amount of organic matter, of which the carbon content is about 50%, which can rapidly increase the fertility of red mud.
[0038] (6) After acid treatment, the agricultural solid waste provided by the present invention has its long-chain carbon molecular structure such as cellulose and lignin destroyed, generating substrates that are easier for microorganisms to utilize, accelerating the decomposition rate, and the large amount of organic acid dissolution promotes the formation of large aggregates, increases the pore structure, makes the red mud more fluffy, and forms a physical structure that makes it easier for plant roots to grow.
[0039] (7) The agricultural solid waste, its leachate, and leachate residue provided by this invention are all natural crops, mainly composed of carbon, nitrogen, oxygen, and phosphorus. The acid treatment uses low concentration and small amount of dilute acid, and there is no risk of secondary pollution during application. Attached Figure Description
[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings in this description are merely embodiments of the present invention.
[0041] Figure 1 This is a process flow diagram of the application of the modifier of the present invention in red mud soilification;
[0042] Figure 2 A graph showing the trend of phytic acid dissolution rate under different pH conditions after treatment with rice bran acid.
[0043] Figure 3 A graph showing the trend of phytic acid dissolution rate under different solid-liquid mass ratios after rice bran acid treatment;
[0044] Figure 4 A graph showing the trend of phytic acid dissolution rate under different soaking times after rice bran acid treatment;
[0045] Figure 5 The pH change trend graphs of the improved red mud in Examples 4-8 and the comparative examples over 30 days are shown.
[0046] Figure 6 The graph shows the trend of conductivity variation of the improved red mud in Examples 4-8 and Comparative Example 1 over 30 days.
[0047] Figure 7 The graph shows the total organic carbon content of the improved red mud of Examples 4-8 and Comparative Example 1 after 30 days.
[0048] Figure 8 The graph shows the available phosphorus content of the improved red mud of Examples 4-8 and Comparative Example 1 after 30 days.
[0049] Figure 9 The graph shows the germination rate of the improved red mud in Examples 4-8 and Comparative Example 1 after 30 days.
[0050] Figure 10 The diagram shows the biomass of the improved red mud in Examples 4-8 and Comparative Example 1 after 30 days.
[0051] Figure 11 The figure shows the average stem length of the improved red mud in Examples 4-8 and Comparative Example 1 after 30 days.
[0052] Figure 12 The diagram shows the average root length of the improved red mud from Examples 4-8 and Comparative Example 1 over 30 days.
[0053] Figure 13 The diagram shows the bulk density of the improved red mud from Examples 4-8 and Comparative Example 1 after 30 days.
[0054] Figure 14 The diagram shows the porosity of the improved red mud from Examples 4-8 and Comparative Example 1 after 30 days. Detailed Implementation
[0055] Embodiments of the present invention are described below, examples of which are shown in the accompanying drawings. The embodiments described with reference to the drawings are exemplary and intended to explain the present invention, but are not to be construed as limiting the present invention.
[0056] Example 1
[0057] The required dilute acid solution can be obtained by diluting concentrated sulfuric acid (98%) purchased as part of the alumina production process, and the same applies below;
[0058] The following steps were taken to explore the changing trend of phytic acid dissolution rate after treatment with rice bran acid at different pH values:
[0059] Rice bran dried at 75℃ for 48 hours was crushed and passed through an 80-mesh sieve. It was then soaked in dilute sulfuric acid with an initial pH of 1-7, at a mass ratio of acid solution to rice bran of 100:25, for 1.5 hours. The phytic acid leaching rate was 16-89.5%, and the trend is detailed in [link to relevant documentation]. Figure 2 .
[0060] Example 2
[0061] The following steps were taken to explore the changing trend of phytic acid dissolution rate after rice bran acid treatment under different solid-liquid mass ratios:
[0062] Rice bran dried at 75℃ for 48 hours was crushed and passed through an 80-mesh sieve. It was then soaked in dilute sulfuric acid with an initial pH of 4, at a mass ratio of acid solution to rice bran of 100:(10-35), for 1.5 hours. The phytic acid leaching rate was 65.8-78.3%, and the trend is detailed in [link to relevant documentation]. Figure 3 .
[0063] Example 3
[0064] The study explored the trend of phytic acid dissolution rate under different soaking times treated with rice bran acid, specifically including the following steps:
[0065] Rice bran dried at 75℃ for 48 hours was crushed and passed through an 80-mesh sieve. It was then soaked in dilute sulfuric acid with an initial pH of 4, at a mass ratio of acid solution to rice bran of 100:25, for 1.5-3.0 hours. The phytic acid leaching rate ranged from 26.8% to 78.2%, with the trend detailed in [link to relevant documentation]. Figure 4 .
[0066] The results of Examples 1-3 show that the phytic acid leaching rate is significantly affected by pH and soaking time; excessively long soaking times may lead to phytic acid decomposition. The highest phytic acid leaching rate was achieved at pH=1, an acid solution to rice bran mass ratio of 100:25, and a soaking time of 1.5 hours. In Example 1, when pH=4, the phytic acid leaching rate was 78.7%, approximately 12% lower than the 89.5% leaching rate at pH=1, but the amount of acid used was only 1 / 1000 of the latter. From the perspective of efficiency and economy, pH=4, an acid solution to rice bran mass ratio of 100:25, and a soaking time of 1.5 hours were selected as the conditions for acid treatment of rice bran in subsequent examples.
[0067] Example 4
[0068] like Figure 1 The application of a soil conditioner in red mud soil transformation specifically includes the following steps:
[0069] (1) Weigh rice bran with a mass ratio of 1:100 to red mud, remove impurities, dry at 75℃ for 48h, pass through an 80-mesh sieve, soak in dilute sulfuric acid with pH 4, the mass ratio of acid solution to rice bran is 100:25, the soaking time is 1.5h, and obtain leachate A1 and leachate residue B1 by filtration.
[0070] (2) After crushing the red mud, pass it through an 80-mesh sieve. Mix the red mud with leachate A1 at a mass ratio of 100:70 and stir for 60 minutes. After filtration, obtain the precipitate dealkalized red mud. Add leachate B1 to the dealkalized red mud and place it in a flowerpot after thorough mixing.
[0071] (3) Ryegrass seeds were sown in flowerpots 3 days after planting. After 30 days, the pH of the red mud was 9.80, and the electrical conductivity was 86.79 μS / cm. For details on the changes in other physicochemical properties, please refer to [link to relevant documentation]. Figure 3-6 See plant growth status Figure 7-10 For details on the physical structure, please refer to [link / reference]. Figure 11-12 and Table 1-3;
[0072] Example 5
[0073] like Figure 1 The application of a soil conditioner in red mud soil transformation specifically includes the following steps:
[0074] (1) Weigh rice bran with a mass ratio of 3:100 to red mud, remove impurities, dry at 75℃ for 48h, pass through an 80-mesh sieve, and soak in dilute sulfuric acid with a pH of 4. The mass ratio of acid solution to rice bran is 100:25, and the soaking time is 1.5h. After filtration, leachate A2 and leachate residue B2 are obtained.
[0075] (2) After crushing the red mud, pass it through an 80-mesh sieve. Mix the red mud and leachate A2 at a mass ratio of 100:70 and stir for 60 minutes. After filtration, obtain the precipitate dealkalized red mud. Add leachate B2 to the dealkalized red mud and place it in a flowerpot after thorough mixing.
[0076] (3) Ryegrass seeds were sown in flowerpots 3 days after planting. After 30 days, the pH of the red mud was 8.55, and the electrical conductivity was 37.29 μS / cm. For details on the changes in other physicochemical properties, please refer to [link to relevant documentation]. Figure 3-6 See plant growth status Figure 7-10 For details on the physical structure, please refer to [link / reference]. Figure 11-12 , and Table 1-3.
[0077] Example 6
[0078] like Figure 1 The application of a soil conditioner in red mud soil transformation specifically includes the following steps:
[0079] (1) Weigh rice bran with a mass ratio of 5:100 to red mud, remove impurities, dry at 75℃ for 48h, pass through an 80-mesh sieve, and soak in dilute sulfuric acid with a pH of 4. The mass ratio of acid solution to rice bran is 100:25, and the soaking time is 1.5h. After filtration, leachate A3 and leachate residue B3 are obtained.
[0080] (2) After crushing the red mud, pass it through an 80-mesh sieve. Mix the red mud with leachate A3 at a mass ratio of 100:70 and stir for 60 minutes. After filtration, obtain the precipitate dealkalized red mud. Add leachate B3 to the dealkalized red mud and place it in a flowerpot after thorough mixing.
[0081] (3) Ryegrass seeds were sown in flowerpots 3 days after planting. After 30 days, the pH of the red mud was 8.17, and the electrical conductivity was 34.93 μS / cm. For details on the changes in other physicochemical properties, please refer to [link to relevant documentation]. Figure 3-6 See plant growth status Figure 7-10 For details on the physical structure, please refer to [link / reference]. Figure 11-12 , and Table 1-3.
[0082] Example 7
[0083] like Figure 1 The application of a soil conditioner in red mud soil transformation specifically includes the following steps:
[0084] (1) Weigh rice bran with a mass ratio of 8:100 to red mud, remove impurities, dry at 75℃ for 48h, pass through an 80-mesh sieve, and soak in dilute sulfuric acid with a pH of 4. The mass ratio of acid solution to rice bran is 100:25, and the soaking time is 1.5h. After filtration, leachate A4 and leachate residue B4 are obtained.
[0085] (2) After crushing the red mud, pass it through an 80-mesh sieve. Mix the red mud and leachate A4 at a mass ratio of 100:70 and stir for 60 minutes. After filtration, obtain the precipitate dealkalized red mud. Add leachate B4 to the dealkalized red mud and place it in a flowerpot after thorough mixing.
[0086] (3) Ryegrass seeds were sown in flowerpots 3 days after planting. After 30 days, the pH of the red mud was 8.07, and the electrical conductivity was 35.53 μS / cm. For details on the changes in other physicochemical properties, please refer to [link to relevant documentation]. Figure 3-6 See plant growth status Figure 7-10 For details on the physical structure, please refer to [link / reference]. Figure 11-12 , and Table 1-3.
[0087] Example 8
[0088] like Figure 1 The application of a soil conditioner in red mud soil transformation specifically includes the following steps:
[0089] (1) Weigh rice bran with a mass ratio of 10:100 to red mud, remove impurities, dry at 75℃ for 48h, pass through an 80-mesh sieve, and soak in dilute sulfuric acid with a pH of 4. The mass ratio of acid solution to rice bran is 100:25, and the soaking time is 1.5h. After filtration, leachate A5 and leachate residue B5 are obtained.
[0090] (2) After crushing the red mud, pass it through an 80-mesh sieve. Mix the red mud with leachate A5 at a mass ratio of 100:70 and stir for 60 minutes. After filtration, obtain the precipitate dealkalized red mud. Add leachate B5 to the dealkalized red mud and place it in a flowerpot after thorough mixing.
[0091] (3) Ryegrass seeds were sown in flowerpots 3 days after planting. After 30 days, the pH of the red mud was 7.55, and the electrical conductivity was 36.47 μS / cm. For details on the changes in other physicochemical properties, please refer to [link to relevant documentation]. Figure 3-6 See plant growth status Figure 7-10 For details on the physical structure, please refer to [link / reference]. Figure 11-12 , and Table 1-3.
[0092] Comparative Example 1
[0093] After crushing the red mud, it was sieved through an 80-mesh sieve. The red mud and deionized water were mixed thoroughly at a mass ratio of 100:70 and then filtered. The precipitate was placed in flowerpots. Ryegrass seeds were sown in the flowerpots 3 days later. After 30 days, the pH of the red mud was 10.56, and its conductivity was 169.67 μS / cm. Other physicochemical properties are detailed below. Figure 3-6 See plant growth status Figure 7-10 For details on the physical structure, please refer to [link / reference]. Figure 11-12 , and Table 1-3.
[0094] Table 1 Results of the improvement of the physicochemical properties of red mud
[0095]
[0096] Table 2 Results of Red Mud Adaptability Improvement
[0097] Processing group Germination rate (%) Biomass (g) Average stem length (cm) Average root length (cm) Comparative Example 1 0 0 0 0 Example 4 45 0.6481 4.81 1.69 Example 5 68 0.9792 4.88 1.83 Example 6 75 1.0814 4.87 1.85 Example 7 78 1.1232 5.01 1.92 Example 8 82 1.1808 5.19 2.02
[0098] Table 3 Results of Red Mud Physical Structure Improvement
[0099] Processing group <![CDATA[Unit weight (g / cm 3 )]]> Porosity (%) Comparative Example 1 1.78 43.27 Example 4 1.73 47.31 Example 5 1.71 45.14 Example 6 1.62 47.56 Example 7 1.60 48.91 Example 8 1.58 50.02
[0100] Depend on Figure 3-12 As can be seen from the data in Tables 1-3, the amount of improver added in Example 4 was small, and its effect on the pH and conductivity of the improved red mud after 30 days was not significant. In the other examples, the pH and conductivity after 30 days of treatment were much lower than those of the red mud in Comparative Example 1 (pH = 10.56, conductivity = 169.67 μs / cm). The pH and conductivity of the rice bran improved by acid treatment showed little change and remained stable within a certain range. The total organic carbon and organic phosphorus content also increased significantly, and the physical structure and adaptability were improved.
[0101] In this embodiment of the invention, the phytic acid dissolution rate in rice bran under different pH values, acid solution-to-rice bran mass ratios, and soaking times was determined using the ferric chloride-spectrophotometric method.
[0102] In this embodiment of the invention, pH, conductivity, total organic carbon, and available phosphorus were used to verify the effect of acid treatment on the physicochemical properties of red mud. The methods for determining the physicochemical properties are as follows:
[0103] pH: Take 2g of red mud, add 10mL of deionized water, shake thoroughly and let stand, then measure the pH of the supernatant.
[0104] Conductivity: Take 2g of red mud, add 10mL of deionized water, shake thoroughly and let stand, then measure the conductivity of the supernatant.
[0105] Total organic carbon: determined by the method of potassium dichromate oxidation-spectrophotometry for the determination of organic carbon in soil (HJ 615-2011).
[0106] Available phosphorus: Determined using the method described in "Determination of Available Phosphorus in Soil - Sodium Bicarbonate Extraction-Molybdenum Antimony Spectrophotometric Method" (HJ704-2014).
[0107] This invention uses plant cultivation to verify the effect of acid-treated rice bran on improving the adaptability of red mud. The selected plant is ryegrass, and the planting container is a flowerpot (bottom diameter 8cm, top diameter 12cm). The measured indicators are: germination rate, biomass, and rhizome length. The method for determining adaptability is as follows:
[0108] Germination rate: The percentage of seeds that germinate in 30 days out of the total number of seeds sown.
[0109] Biomass: Plant samples were dried at 65°C to constant weight (2 days) and weighed to obtain mass.
[0110] Rhizome length: average of 10 randomly selected plants in each example.
[0111] This invention uses bulk density and porosity to verify the effect of acid-treated rice bran on improving the physical structure of red mud. The method for determining the physical structure is as follows:
[0112] Bulk density: Measured using the ring cutter method, it is the ratio of the difference between the dry weight of red mud and the mass of the ring cutter to the volume.
[0113] Porosity: Measured using the ring cutter method, it is the percentage of the difference between the water-saturated mass of red mud and the dry weight of red mud to the volume.
[0114] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A low-cost red mud soil conditioner for dealkalization and fertilization, characterized in that, This includes the following leaching residue and leachate; The leaching residue and leachate are obtained by solid-liquid separation of agricultural solid waste with high phytic acid content after acid treatment. The mass ratio of the agricultural solid waste with high phytic acid content to red mud is (1-10):100; The acid treatment uses any one of the dilute acid solutions with a pH of 2-6; the mass ratio of the dilute acid solution to the agricultural solid waste with high phytic acid content is 100:(10-35); the acid treatment time is 0.5-3 hours.
2. The low-cost red mud soil conditioner for dealkalization and fertilization according to claim 1, characterized in that, The agricultural solid waste with high phytic acid content is at least one of rice bran, wheat bran, and oat bran.
3. The low-cost red mud soil conditioner for dealkalization and fertilization according to claim 1, characterized in that, The agricultural solid waste with high phytic acid content was dried at 60-75℃ for 48 hours before acid treatment and then passed through a 40-80 mesh sieve.
4. The low-cost red mud soil conditioner for dealkalization and fertilization according to claim 1, characterized in that, The dilute acid solution is any one of sulfuric acid, hydrochloric acid, nitric acid, and phytic acid.
5. The application of the amendment as described in any one of claims 1-4 in the red mud soil treatment.
6. The application according to claim 5, characterized in that, The method of using the improver is as follows: (1) After mixing and reacting the red mud and leachate, the precipitate obtained is the dealkalized red mud; (2) After mixing the dealkalized red mud with the leaching residue and piling it up for fertilization, soil-based red mud is obtained.
7. The application according to claim 6, characterized in that, In step (1), the mass ratio of the red mud to the leachate is 100:70, and the reaction time is 60 min.
8. The application according to claim 6, characterized in that, The red mud mentioned in step (1) is the red mud discharged after pressure filtration or the red mud that has been stockpiled and passed through a 40-80 mesh sieve.
9. The application according to claim 6, characterized in that, The composting time in step (2) is 7-30 days, and the composting temperature is controlled at 15-35℃.