Method for improving nutrients and structure of bauxite slime

Abstract

The invention relates to a method suitable for solving the problems of low nutrient and poor physical structure of bauxite slime, which comprises the following steps: fully mixing a modifier with bauxite slime according to a mass ratio of 5%, sowing leguminous plant peanuts, and synergistically improving the nutrient and structure of the bauxite slime through the peanuts and the modifier. The peanuts can be symbiotic with rhizobium in the slime to form root nodules. In the root nodules, the rhizobium can convert nitrogen in the atmosphere into ammonia which can be utilized by plants, nitrogen nutrition is provided for the peanuts, and therefore the fertility of the slime is improved. The modifier can be used for improving the slime in various ways, including improving the structure of the slime, adjusting the pH value, increasing the fertility, improving the erosion resistance and the like, so that the crop yield and the slime quality are improved. According to the method, three improvers are selected to synergistically improve the slime with the peanuts, and the improvement effect is comprehensively improved by utilizing the improvement advantage of the improvers on the slime structure and the nitrogen fixation characteristic of peanut root nodules. The method is efficient and environment-friendly, and raw materials are easy to obtain and low in price.

Description

Technical Field

[0001] The invention belongs to the technical field of soil remediation, and in particular relates to a method for improving the nutrients and structure of bauxite mud. Background Art

[0002] Bauxite is an important strategic resource for China. With the rapid development of industrialization, China has become the world's largest aluminum producer and consumer. Due to the uneven development level of the aluminum industry in various places, the huge market and mining scale have brought many ecological and environmental problems, among which the problem of reasonable digestion of a large amount of stockpiled sludge is particularly prominent. At present, the mainstream methods of sludge treatment include adding modifiers for physical improvement and in-situ covering for plant restoration. However, due to the extremely poor aggregate structure and poor nutrients of sludge, it is difficult for single methods such as physical improvement and plant restoration to achieve ideal results. Therefore, it is urgent to seek an efficient improvement method that can not only improve the aggregate structure of sludge but also improve its nutrients. Modifiers can change the physical properties of soil, increase soil capillary pores and non-capillary pores, reduce soil bulk density, increase soil aeration and saturated hydraulic conductivity, and improve soil environment, thereby increasing crop yields and improving crop quality. Leguminosae can coexist with rhizobia to form nodules for biological nitrogen fixation. This process can increase the nitrogen content in the soil and improve soil fertility. The planting of leguminous plants can also increase the organic carbon content in the soil through root secretions, residual root input and higher microorganisms, thereby improving the soil structure and aggregate composition. The present invention uses modifiers and plants to synergistically improve bauxite mud, which can not only improve the problem of poor mud structure but also improve the nutrients of the mud. It is a very efficient and environmentally friendly method; it has long-term significance for the resource utilization of bauxite mud and the development of mining area agriculture. Summary of the invention

[0003] The purpose of the present invention is to fill the technical gap of improving the low-nutrient and poor-agglomerate structure of bauxite sludge and provide a cheap and efficient technical method.

[0004] In order to achieve the above object, the present invention provides a technical solution, which specifically comprises the following steps:

[0005] (1) Dry the three amendments, vermiculite, biochar and humus, separately and pass them through a 2 mm sieve.

[0006] (2) Place the fresh mineral mud in a cool and ventilated place, air-dry it, and then pass it through a 1 cm sieve.

[0007] (3) After steps (1) and (2) are completed, add the improver to the mineral mud, mix thoroughly, and then pot it in preparation for the potted plant test.

[0008] (4) Place the peanut seeds in a culture dish and soak them for germination.

[0009] (5) After steps (3) and (4) are completed, the processed peanut seeds are buried in bauxite mud mixed with different improvers and allowed to grow into plants.

[0010] (6) After step (5) is completed, the organic matter, total nitrogen, total phosphorus, available potassium, sucrase, urease and alkaline phosphatase activities in the sludge are measured, and the effects of peanuts and different improvers on the fertility of the sludge are analyzed; the bulk density, porosity and aggregate indexes of the bauxite sludge are measured, and the effects of peanuts and different improvers on the sludge structure are analyzed; the improvers most suitable for planting in the bauxite reclamation area are screened out to improve the arableness of the bauxite sludge, realize the resource utilization of industrial solid waste, and thus protect the sustainable development of the ecological environment.

[0011] Preferably, the amount of the modifier added in step (3) is 5% of the mass of the sludge.

[0012] Preferably, in step (4), the peanut seeds are soaked for 24 hours, the germination temperature is 25-30° C., and the germination time is 3-4 days.

[0013] Preferably, in step (5), after sowing the seeds, five seedlings with relatively uniform growth are selected; chemical agents are used to prevent insects and weeding is done manually during the growth period; and the positions of the flower pots are exchanged every week to ensure that the flower pots with different treatments are randomly placed.

[0014] Preferably, the indicators for determining the fertility of the sludge in step (6) include organic matter, total nitrogen, total phosphorus, available potassium, sucrase, urease and alkaline phosphatase activities in the soil; and the indicators for determining the structure of the sludge include the particle size composition of the sludge aggregates and their stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The figure is a comparison of the contents of organic matter, total nitrogen, total phosphorus and available potassium in the sludge under different improvement conditions of the present invention.

[0016] Figure 2 The figure is a comparison of the activities of sucrase, urease and alkaline phosphatase in the mineral mud under different improved conditions of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be comprehensively and clearly explained below through specific implementation methods.

[0018] The ore mud sample involved in the present invention is taken from the ore mud yard of Guangxi Pingguo Aluminum and Aluminum Factory. After the ore mud is collected, it is placed in a dark and ventilated place. After the ore mud is dried in the shade, it is ground and mixed to pass through a 1cm sieve for use. The three modifiers used, vermiculite, biochar and humus, are purchased from the market respectively. After the modifier is purchased, it is dried and passed through a 2mm sieve for use. The plant seeds used in the present invention are peanuts.

[0019] The improver (5% by weight of the sludge) was fully mixed with the sludge and placed in the test pots. The sludge mass of each pot was 4.5 kg. The pots were watered uniformly and placed in the greenhouse for one week to balance.

[0020] Select peanut seeds with full and healthy seeds for surface disinfection, and use 3% H 2 O 2 After soaking for 30 minutes, wash with clean water, soak in ultrapure water for 24 hours, and then place in an incubator at 25-30℃ for germination for 3-4 days. When the seed buds are about 1-2 cm long, transfer them to the test pots. Do 3 replicates under each improved condition, sow 8 seeds in a diamond pattern in each pot, bury about 2 cm deep, and select 5 seedlings with relatively consistent growth after germination.

[0021] During the peanut planting period, the soil moisture was kept at about 50% of its maximum field water holding capacity by regular irrigation. Chemical insecticides were used for pest control and manual weeding was performed during the growth period. During the planting process, the position of the test pots was changed regularly to ensure that the humidity, temperature, light and other conditions were consistent between the treatments, and a soil blank control was set at the same time.

[0022] The mineral mud matrix samples were collected after the plants matured for 120 days. The planted plants were carefully separated from the mineral mud, and the residual roots and debris in the mineral mud were carefully picked out with tweezers. Subsequently, a portion of the fresh soil was sieved through a 2mm sieve for the determination of the mineral mud enzyme activity, and the remaining mineral mud was air-dried and sieved for the determination of other mineral mud physical and chemical properties.

[0023] The effects of different amendments and peanuts on the nutrient content of mineral mud are shown in Table 1. As can be seen from Table 1, compared with the mineral mud blank, the organic matter, total nitrogen, total phosphorus and available potassium contents of the experimental group of amendments and peanuts were significantly increased. Among them, the highest content of organic matter index was in the experimental group of biochar and peanuts, which was 55.49g / kg, an increase of 428.48% compared with the mineral mud blank; the highest content of total nitrogen was in the experimental group of vermiculite and peanuts, which was 3.47g / kg, an increase of 67.63% compared with the mineral mud blank; the highest content of total phosphorus was in the experimental group of biochar and peanuts, which was 0.15g / kg, an increase of 36.37% compared with the mineral mud blank; the highest content of available potassium was in the experimental group of biochar and peanuts, which was 418.56mg / kg, an exponential increase compared with the mineral mud blank treatment. In summary, the synergistic improvement of various amendments with peanuts will significantly increase the content of organic matter, total nitrogen, total phosphorus and available potassium in the mud, and improve the nutrients of bauxite mud. Among them, the synergistic improvement effect of biochar and peanuts is the most significant.

[0024] Table 1 Nutrient content of sludge under different improvement conditions.

[0025]

[0026] Note: Different lowercase letters after the data in the same column indicate significant differences (P<0.05), the same as in Tables 2 and 3

[0027] The effects of different amendments and peanuts on the activity of slurry sucrase in the mineral mud are shown in Table 2. As can be seen from the table, compared with the mineral mud blank, the slurry sucrase activity of the experimental groups of amendments and peanuts was significantly improved, among which the slurry activity of humus soil was the highest, which was 8.49 mg / g·24h; followed by biochar and vermiculite, which were 6.43 mg / g·24h and 3.03 mg / g·24h, respectively. Compared with the slurry activity of the mineral mud blank, the experimental groups of each amendment and peanuts were improved by 239.60%, 157.20% and 21.20%, respectively. In summary, the experimental groups of each amendment and peanuts will significantly improve the slurry sucrase activity; among them, the effect of humus soil and peanuts in synergistic improvement is better.

[0028] The effects of different amendments and peanuts on the alkaline phosphatase activity of mineral mud are shown in Table 3. It can be seen from the table that compared with the mineral mud blank, the alkaline phosphatase activity of the experimental groups of amendments and peanuts was improved. Among them, the alkaline phosphatase activity of humus soil was the highest, which was 0.10 mg / g·2h; followed by biochar and vermiculite, which were 0.08 mg / g·2h and 0.05 mg / g·2h, respectively. Compared with the alkaline phosphatase activity of the mineral mud blank, the experimental groups of each amendment and peanuts increased by 164.86.00%, 102.70% and 43.24%, respectively. The effects of different amendments and peanuts on the alkaline phosphatase activity of mineral mud were also different, in the order of humus soil>biochar>vermiculite. In summary, the synergistic improvement of amendments and peanuts will significantly increase the alkaline phosphatase activity of mineral mud; among them, the synergistic improvement of humus soil and peanuts has the best effect.

[0029] The effects of different amendments and peanuts on the urease activity of mineral mud are shown in Table 2. It can be seen from the table that compared with the mineral mud blank, the urease activity of the mineral mud components improved by the amendment and peanuts has increased. Among them, the urease activity of biochar is the highest, which is 0.40 mg / g·24h; followed by biochar, which is 0.38 mg / g·24h; the urease activity of biochar is the lowest, which is 0.27 mg / g·24h. Compared with the urease activity of the mineral mud blank, humus and biochar increased by 60.00% and 52.00%, respectively. The effects of different amendments on the urease activity of mineral mud are also different, in the order of humus>biochar>vermiculite. In summary, the synergistic improvement of amendments and peanuts will improve the urease activity of mineral mud; among them, the synergistic improvement of humus and peanuts has the best effect.

[0030] Table 2 Enzyme activities of mineral mud under different improvement conditions.

[0031]

[0032] Table 2

[0033]

[0034] The particle size composition and stability of the aggregates of the mineral mud matrix under different improvement conditions are shown in Table 3. It can be seen from Table 3 that the mass fraction of the 0.25-2mm component in the mineral mud matrix of the component improved by the modifier and peanut is significantly higher than that of the mineral mud blank control, and the mass fraction of the 0.25-2mm component is the highest. The average mass diameter and geometric mean diameter of the mineral mud matrix aggregates of the component improved by the modifier and peanut are significantly higher than those of the mineral mud blank, indicating that after the modifier and peanut are improved in a coordinated manner, the stability of the mineral mud matrix aggregates is improved. The improvement effects are biochar>vermiculite>humus soil.

[0035] Table 3 Particle size composition and stability of sludge aggregates under different improvement conditions.

[0036]

[0037] Considering the effects of nutrient content, enzyme activity and aggregates of the mineral mud, the experimental groups treated with different improvers and peanuts all had relatively significant improvement effects, among which the experimental group treated with biochar and peanuts had the best effect. Under the conditions of biochar and peanuts synergistic improvement, the nutrients, enzyme activity and stability of mineral mud aggregates were significantly improved. Compared with the mineral mud blank, the organic matter content of the mineral mud with biochar added increased by 428.48%, the sucrase activity increased by 157.20%, and the stability of mineral mud aggregates increased by 38.64%. Therefore, the method of biochar and peanuts synergistic improvement is very suitable for promotion and use as a technology for improving bauxite mud.

Claims

1. A method for improving the nutrients and structure of bauxite mud, characterized in that The improver comprises one or more of vermiculite, biochar and humus; and the plant is peanut.

2. The use according to claim 1, characterized in that: Mix the amendment with bauxite sludge evenly and sow the plants.

3. A method for improving the nutrients and structure of bauxite mud, characterized in that: The following steps are involved: (1) The three amendments, vermiculite, biochar and humus, were dried separately and passed through a 2 mm sieve; (2) Place the fresh sludge in a cool and ventilated place, air dry it and then pass it through a 1 cm sieve; (3) After steps (1) and (2) are completed, mix the two thoroughly and place them in pots to prepare for potted plant experiments; (4) placing the peanut seeds in a culture dish for soaking and germination; (5) After steps (3) and (4) are completed, the treated peanut seeds are buried in bauxite mud mixed with different improvers to wait for the seeds to grow into plants; (6) After step (5) is completed, the soil organic matter, total nitrogen, total phosphorus, available potassium, sucrase, urease, alkaline phosphatase activity and other indicators are measured, and the effects of peanuts and different improvers on the fertility of bauxite mud are analyzed; the particle size composition and stability of bauxite mud aggregates are determined, and the effects of peanuts and different improvers on the mud structure are analyzed; the most suitable improver for use in bauxite reclamation areas is screened out to improve the suitability of bauxite mud for cultivation, realize the resource utilization of industrial solid waste, and thus protect the sustainable development of the ecological environment.

4. The method according to claim 3, characterized in that The mixed addition amount of the modifier in step (3) is uniformly 5% of the mass of the bauxite sludge.

5. The method according to claim 3, characterized in that: In the step (4), the peanut seeds are soaked for 24 hours, the germination temperature is 25-30° C., and the germination time is 3-4 days.

6. The method according to claim 3, characterized in that In the step (5), after sowing the seeds, five seedlings with relatively uniform growth are selected; during the growth period, chemical pesticides are used to prevent insects and weeding is done manually; and the positions of the flower pots are exchanged every week to ensure that the flower pots with different treatments are randomly placed.

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