Saline-alkali soil conditioner based on two tailing-based composite organic matters and preparation method of saline-alkali soil conditioner

Abstract

The invention discloses a saline-alkali soil conditioner based on two tailing-based composite organic matters and a preparation method of the saline-alkali soil conditioner. The saline-alkali soil conditioner is prepared from iron tailings, molybdenum tailings, optimized wormcast organic matters, wood vinegar and ammonium sulfate according to the part ratio of 20: 15: 5: 1: 1. According to the method, the low-molecular organic acid is adopted to fully consider the synergistic utilization of the two tailings, so that mineral solid wastes are effectively reduced, the content of organic matters and trace elements necessary for plants in the saline-alkali soil is remarkably increased, the soil structure is adjusted, the salinity and alkalinity are reduced, the soil environment is remarkably improved, and the growth condition of the plants is improved; the soil conditioner has a good improvement effect on medium-low saline alkali soil. The main raw materials of the modifier belong to mineral industry solid wastes, the used raw materials are easy to obtain, low in cost and free of pollution, the technical scheme is simple and easy to operate and convenient to implement, and rationalized and resource pollution-free comprehensive utilization of the solid wastes is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of mineral waste recycling and soil improvement, and in particular to a saline-alkali soil improver based on two tailings-based composite organic matters and a preparation method thereof. Background Art

[0002] Soil salinity is one of the important abiotic stresses for crops. Excessive salinity can disrupt ion uptake and homeostasis in plant tissues, thereby interfering with the synthesis and metabolism of many substances, causing toxicity to plants, and becoming a key factor restricting the production of some farmlands. The existing saline-alkali soil improvement technologies mainly include improving soil drainage, chemical leaching, and breeding of salt-tolerant plant varieties. However, there are inevitably some disadvantages in these methods. Drainage helps to lower the groundwater level, but the cost is high. Using fresh water to press salt is conducive to transferring salt from the plant root zone to deeper soil, but it is difficult to achieve in areas where fresh water is scarce. Chemical reagents can react with certain types of salt and remove them from the soil, but this method is costly and may lead to other negative environmental consequences. The breeding and genetic modification of salt-tolerant plants in saline-alkali soils have a long cycle and high technical costs.

[0003] Iron tailings and molybdenum tailings refer to the remaining ore after iron is extracted from iron and molybdenum ores. They are the main solid wastes of mining production. The radioactive elements and intensity meet the national environmental protection requirements. Calcium and magnesium in the two tailings are important medium-amount elements for plant growth. They also contain a variety of trace elements necessary for plants, such as iron, molybdenum, and copper, and have potential application value in the process of soil improvement.

[0004] In recent years, research has found that tailings have great development potential in the field of soil improvement, especially iron tailings with simple components are relatively more widely used. For example, the existing patents CN112322305A, CN108795440A, CN110317097A, CN114887584A, CN116574518B, CN 118895147A, CN118235567A, and CN 112322305A mostly use single iron tailings and biochar or rice husks, ceramsite, organic fertilizer, and attapulgite powder as raw materials for improvers. Some of them are combined with water, ethanol, hydrochloric acid, etc. to modify saline-alkali soil, but the problems of insufficient activation of trace elements and lack of targeted adsorption of saline-alkali ions have not been solved. These improvement measures usually focus on a single soil indicator and ignore the synergistic effect of "plant-soil-improvement agent".

[0005] To sum up, due to the singleness of the existing technology in the comprehensive utilization of mineral waste and the improvement of saline-alkali soil, the mineral components have not been fully utilized. The present invention proposes a composite soil conditioner based on two tailings. When the basic element detection determines that the harmless ions are zero, the effective trace elements in the tailings are activated by reasonably combining earthworm castings, organic matter, and organic acids in a reasonable ratio, thereby providing a saline-alkali improvement plan that can effectively reduce soil salt concentration, improve soil structure, and enhance soil fertility. At the same time, it solves the problem of solid waste disposal and storage in mine production, and has strong practical value and promotion prospects in saline-alkali soil improvement and comprehensive utilization of bulk waste. Summary of the invention

[0006] The purpose of the present invention is to provide a saline-alkali soil conditioner based on two tailings-based composite organic matter and a preparation method thereof. It is found that iron tailings (rich in Fe³⁺) and molybdenum tailings (containing MoO4²⁻) can synergistically improve the soil aggregation structure under the activation of wood vinegar, adsorb salt ions in saline-alkali soil, and release Fe and Mo elements essential to plants, thereby solving the technical problems mentioned in the background technology.

[0007] A saline-alkali soil conditioner based on two tailings-based composite organic matters, the saline-alkali soil conditioner consists of iron tailings, molybdenum tailings, optimized earthworm castings organic matter, wood acetic acid and ammonium sulfate in a proportion of 10-25:5-20:5-10:1:1.

[0008] As a further technical solution of the present invention, the saline-alkali soil conditioner is composed of iron tailings, molybdenum tailings, optimized earthworm castings organic matter, wood acetic acid, and ammonium sulfate in a ratio of 20:15:5:1:1.

[0009] As a further technical solution of the present invention, the optimized earthworm castings organic matter is prepared by mixing earthworm castings and organic matter in a ratio of 7:3, composting for 5 days at a temperature not lower than 25°C, and then naturally drying to a moisture content not higher than 8%.

[0010] Another object of the present invention is to provide a method for preparing a saline-alkali soil conditioner based on two tailings-based composite organic matter as described above, comprising the following steps:

[0011] S1. Preparation of optimized vermicompost organic matter: Mix vermicompost and organic matter in a ratio of 7:3, ferment at no less than 25°C for no less than 5 days, and dry naturally to a moisture content of no more than 8%;

[0012] S2, iron tailings and molybdenum tailings are graded and screened, passed through a 200 sieve, and set aside; 20 parts of the screened iron tailings and 15 parts of the molybdenum tailings are respectively mixed with 1 part of wood acetic acid, sealed at 40-50°C for 24-48 hours, activated to obtain modified iron tailings and modified molybdenum tailings, and the modified iron tailings and modified molybdenum tailings are mixed to obtain mixed tailings;

[0013] S3, fully mixing the mixed tailings with 5 parts of optimized earthworm castings organic matter, composting for 2-3 days at a temperature not lower than 25° C., to obtain a tailings-based organic matter complex with a water content of ≤8%;

[0014] S4, grinding the tailings-based organic compound at 400-600 rpm for 2-4 hours to obtain a modified tailings-based organic compound;

[0015] S5, mixing the modified tailings-based organic compound with 1 part of ammonium sulfate, stirring in a stirrer at a stirring speed of 150-300 rpm for 10-15 minutes to obtain a fully mixed tailings compound;

[0016] S6. The fully mixed two tailings complex obtained in S5 is aged at a temperature not lower than 25° C. for 3-5 days to obtain a saline-alkali soil conditioner.

[0017] Beneficial effects achieved by the present invention:

[0018] (1) In order to take into account the resource utilization of large amounts of solid waste from the mining industry, the present invention optimizes and improves iron tailings and molybdenum tailings rich in trace elements, wood vinegar, an organic acid that can adjust the pH value of saline-alkali soil, and earthworm manure organic matter with a granular structure through physical means such as mixed fermentation and acid treatment, with the goal of synergistically improving the functions of optimizing soil structure, reducing salinity, and improving soil fertility. The screening and modification technologies and compounding schemes of different components are analyzed, with the goal of synergistically improving the physical structure and fertility of saline-alkali soil, such as soil bulk density, soil salinity, organic matter, and alkaline nitrogen. A multifunctional green soil conditioner is prepared, which has the advantages of low production cost and good improvement effect, and can be applied to the field of saline-alkali soil improvement.

[0019] (2) The improver of the present invention significantly increases the content of trace elements and organic matter in saline-alkali soil, effectively improves soil fertility, and regulates soil pH. The silicon element in the two tailings improves soil aggregation, improves soil structure, and improves soil water retention capacity, providing a suitable environment for plant growth, improving plant emergence and growth conditions, and achieving good results in improving low and medium saline-alkali soils.

[0020] (3) The main raw materials of the improver of the present invention are solid waste from the mineral industry. The raw materials used are easy to obtain, low in cost, and pollution-free. The technical solution is simple and easy to operate, and is easy to implement. It realizes the rationalization and resource-based pollution-free comprehensive utilization of solid waste. It is a practical technology that conforms to the concept of green solid waste reduction and has practical application value.

[0021] After the implementation of the two tailings-based saline-alkali soil organic composite improver technologies, the saline-alkali soil environment can be improved, soil fertility can be increased, and vegetation emergence, growth and quality can be promoted, thereby achieving the effect of continuously improving the soil ecological environment. From the perspective of economic benefits, the mining production solid waste used in the present invention as the main component of the improver not only effectively solves the problem of mineral solid waste disposal and storage, but also alleviates the environmental burden, and the improver components are non-toxic and pollution-free, which promotes the ecological improvement of saline-alkali soil. By optimizing means, the utilization efficiency of iron tailings waste is improved. Compared with the traditional more complicated process flow, the process used by this improver is simple and easy to operate, which is convenient for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the main effect diagram of the potted plant experiment provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below in conjunction with the specific drawings.

[0024] The present invention optimizes the treatment of mineral solid wastes, uses small molecule organic acids, and gives full play to the dissolution and precipitation effect of minerals in the two tailings. The two tailings of the proportioning materials are modified and the proportions are adjusted to make them suitable for low and moderate saline-alkali soil improvement. The trace element activation effect of the two mineral solid wastes under the conditions of organic acid and earthworm castings is explored, aiming to develop improvement materials suitable for saline-alkali soils, improve the green recycling of mining solid waste iron tailings, and provide new ways for the comprehensive utilization of bulk mineral wastes and saline-alkali soil improvement.

[0025] An embodiment of the present invention provides a saline-alkali soil conditioner based on two tailings-based composite organic matter, wherein the saline-alkali soil conditioner is composed of iron tailings, molybdenum tailings, optimized earthworm castings organic matter, wood acetic acid, and ammonium sulfate in a ratio of 20:15:5:1:1.

[0026] The preferred embodiment of the present invention provides a novel saline-alkali soil conditioner, wherein the proportion of the components is: iron tailings: molybdenum tailings: optimized earthworm castings organic matter: wood acetic acid: ammonium sulfate is 20:15:5:1:1. The earthworm castings organic matter includes earthworm castings and organic matter mixed in a ratio of 7:3. The effect is verified by potted plant experiments.

[0027] The embodiment of the present invention provides a method for preparing a saline-alkali soil conditioner based on two tailings-based composite organic matters, comprising the following steps:

[0028] S1. Preparation of optimized earthworm castings and organic matter: Mix earthworm castings and organic matter in a ratio of 7:3, compost for not less than 5 days under natural conditions of not less than 25°C in summer, dry naturally to a moisture content of not more than 8%, and set aside;

[0029] S2, iron tailings and molybdenum tailings are graded and screened, passed through a 200 sieve, and set aside; 20 parts of the screened iron tailings and 15 parts of the molybdenum tailings are respectively mixed with 1 part of wood acetic acid, sealed at 40-50°C for 24-48 hours, activated to obtain modified iron tailings and modified molybdenum tailings, and the modified iron tailings and modified molybdenum tailings are mixed to obtain mixed tailings;

[0030] S3, fully mixing the mixed tailings with 5 parts of optimized earthworm castings organic matter, composting for 2-3 days at a temperature not lower than 25° C., to obtain a tailings-based organic matter complex with a water content of ≤8%;

[0031] S4, grinding the tailings-based organic compound at 400-600 rpm for 2-4 hours to obtain a modified tailings-based organic compound;

[0032] S5, mixing the modified tailings-based organic compound with 1 part of ammonium sulfate, placing in a stirrer and mixing thoroughly, the stirring speed is controlled at 150-300 rpm, the stirring time is 10-15 minutes, and the two tailings compounds are fully mixed;

[0033] S6. The fully mixed two tailings complex obtained in S5 is aged at a temperature not lower than 25° C. for 3-5 days to obtain a saline-alkali soil conditioner.

[0034] In order to facilitate those skilled in the art to better understand the technical solution of the present invention, specific embodiments of the present invention are given as follows:

[0035] The planting soil of the present invention is saline-alkali soil taken from Caofeidian Ecological City, Tangshan, Hebei Province, and has a moderate salinity.

[0036] The improved and optimized tailings in the invention effectively increase the trace beneficial elements in the saline-alkali soil, reduce the salinity of the soil by replacing the main salt ions, reduce the soil pH value by organic acids and composting organic matter, and the modified saline-alkali soil conditioner has a good agglomeration effect, and the contact area with the soil particles is increased, thereby improving the soil physical properties and organic matter content. The content of soil N is increased by adding ammonium sulfate, which has a good promoting effect on improving soil fertility and plant growth, thereby achieving a good improvement effect on the saline-alkali soil.

[0037] Screening of optimal ratio of saline-alkali soil conditioner:

[0038] The experiment selected the reclaimed saline-alkali soil for analysis through gradient test. Under the condition that the proportion of wood vinegar and ammonium sulfate remained unchanged, different proportions of iron tailings, molybdenum tailings and optimized earthworm manure were designed. Three groups of repeated controls were set for each treatment to determine the optimal proportion of iron tailings, molybdenum tailings, earthworm manure organic matter, wood vinegar and ammonium sulfate in soil conditioner. The specific steps are as follows:

[0039] S1. Preparation of optimized vermicompost organic matter: Mix vermicompost and organic matter in a ratio of 7:3, age them at no less than 25°C for 5 days, and then dry them naturally until the moisture content is no more than 8%;

[0040] S2, iron tailings and molybdenum tailings are graded and screened, passed through a 200 sieve, and set aside; 10, 15, 20, and 25 parts of the screened iron tailings and 5, 10, 15, and 20 parts of the molybdenum tailings are cross-combined according to the experimental scheme in Table 1, and each tailing is fully mixed with 1 part of wood vinegar, sealed at 40°C, sealed for 24 hours, and activated to obtain modified iron tailings and modified molybdenum tailings, and each group of modified modified iron tailings and modified molybdenum tailings are mixed to obtain mixed tailings;

[0041] S3, combining the mixed tailings with 5 and 10 parts of the optimized earthworm castings organic matter according to the experimental design in Table 1, mixing and composting at a temperature not lower than 25° C. for 3 days, and obtaining a tailings-based organic matter composite with a water content of ≤8%;

[0042] S4, grinding the tailings-based organic compound at 400 rpm for 2 hours to obtain modified tailings-based organic compounds of different treatment groups;

[0043] S5. The modified tailings-based organic matter composites of different treatment groups were combined according to the experimental design in Table 1 and mixed with 1 part of ammonium sulfate respectively, and placed in a stirrer for thorough mixing and stirring. The stirring speed was controlled at 200 rpm for 30 minutes to obtain two tailings composites of different treatment groups that were thoroughly mixed.

[0044] S6. The two tailings composites of different treatment groups obtained in S5 are fully mixed and aged at a temperature not lower than 25° C. for 3 days to obtain saline-alkali soil conditioners in different proportions.

[0045] The combinations of amendments are shown in Table 1. Untreated saline-alkali soil was set as a control in each test group.

[0046] Table 1 Experimental design table

[0047]

[0048] The test selected uncultivated wasteland with moderate salinity and alkalinity for the test. The soil was passed through a 3mm sieve, and the sieved soil was mixed with the amendment (15% of the total mass of the soil), and watered and potted at 70% of the maximum water holding rate. The flower pots were 20cm in diameter and 25cm in height, with drainage holes at the bottom. Before filling the soil, non-woven fabrics were placed at the bottom, and about 2cm of gravel was placed at the bottom. Vaseline was applied to the wall of the flower pot to prevent edge effects with the soil. During the period, regular watering was carried out using the weight method to maintain a maximum water holding rate of 60-70%, and the soil was loosened regularly. After balancing for 30 days, the indicators were measured.

[0049] The experimental groups (T1-T16) and control groups (T control) of the test results and their indicators were subjected to principal component analysis (PCA). The T control group was a group without soil conditioner addition, in which reverse indicators such as organic matter, available phosphorus, available potassium, available silicon, available iron, bulk density, pH value, and soil salinity were subjected to reverse treatment. According to the PCA comprehensive score evaluation and sorting, as shown in Table 2, the T11 and T15 test groups had the highest scores and the best improvement effects, and the differences were not large. Considering the recycling value of iron tailings and the cost of organic fertilizers, T11 was selected as the improver formula for the saline-alkali land of the present invention, that is, iron tailings: molybdenum tailings: optimized earthworm manure organic matter: wood acetic acid: ammonium sulfate = 20:15:5:1:1. The treatments of different gradients were measured, and the PC1, PC2, and PC2 factor values ​​ranked in the top three in terms of contribution rate were taken, and the principal component analysis score table is shown in Table 2.

[0050] Table 2 Scores and rankings of screening analysis with different ratios

[0051]

[0052] Soil conditioners improve the structure, salinity and fertility of saline-alkali soils:

[0053] The test selected uncultivated wasteland with moderate salinity and alkalinity for the test. The soil was sieved through a 3mm sieve, and the sieved soil was mixed with the improver (15% of the total mass of the soil) with a ratio of iron tailings: molybdenum tailings: optimized earthworm manure organic matter: wood acetic acid: ammonium sulfate = 20:15:5:1:1 obtained under the improver preparation process and conditions of the present invention, and watered and potted at 70% of the maximum water holding rate. The flower pot has a diameter of 20cm and a height of 25cm, and there is a drainage hole at the bottom. Before filling the soil, a non-woven fabric is placed at the bottom, and about 2cm of gravel is placed at the bottom. Vaseline is applied to the wall of the flower pot to prevent edge effects with the soil. During the period, the weight method is used for regular watering to maintain a maximum water holding rate of 60-70%, and the soil is loosened regularly. After balancing for 30 days, the soil is collected and the soil physical and chemical indicators such as organic matter, alkaline nitrogen, available phosphorus, available potassium, available silicon, available iron, bulk density, pH value, and soil salt content are measured. Taraxacum officinale was selected as the target vegetation for observation. After 45 days of pot planting, the soil without conditioner was used as the control (T control). Three replicates (TW1, TW2, TW3) were set for each treatment to measure the seedling rate, maximum plant height, aboveground biomass, MAD, and SOD parameters. The soil conditioner was added to the saline-alkali soil at 15%, and the improvement effect is shown in Table 3.

[0054] Table 3 Effects of amendments on saline-alkali soil

[0055]

[0056] As shown in Table 3, the improver has a significant improvement effect on saline-alkali soil, and has a significant improvement effect on alkaline nitrogen, effective phosphorus and quick-acting potassium in the soil, with the highest increase of 67.7%, 52.6% and 21.8%. The trace elements are improved well, such as effective molybdenum, iron and silicon, which have increased significantly, reaching 55.6%, 60.2% and 66.9%, and the organic matter has increased well by 84.1%. In addition, it can be seen from the table that the improver has a certain improvement effect on the bulk density and porosity of saline-alkali soil, and improves the physical properties of the soil. It can be seen from the improvement effect of the pH value and conductivity of the soil in the treatment group that the improver of the present invention has a significant improvement effect on the saline-alkali properties of saline-alkali soil.

[0057] In order to verify the effect of the modifier formula of the present invention (the modifier with a ratio of iron tailings: molybdenum tailings: optimized earthworm castings organic matter: wood acetic acid: ammonium sulfate = 20:15:5:1:1) and determine the appropriate amount of addition, dandelion was used as the cultivation object, and saline-alkali soil with medium salinity was selected as the experimental soil. Potted planting experiments were carried out by adding modifiers at 5%, 10%, 15%, and 20% by mass. Each treatment was repeated 3 times, and the group without added modifiers was used as the control group. In this way, the effects of different dosages on the emergence rate, maximum plant height, maximum biomass and enzyme activity of dandelion plants were explored. Through a comprehensive analysis of the above-mentioned indicators, the effectiveness of the soil conditioner was verified and the optimal dosage was determined. The ranking of different addition amounts was obtained through principal component analysis (PCA), as shown in Table 4, and the differences in vegetation growth effects are shown in Table 4. Figure 1 ,From left to right in the figure are 5%-20% treatment groups. From the measured data analysis, it can be seen that the difference between 15% and 20% is not significant. Considering the cost-effectiveness, it is recommended to use a 15% addition amount.

[0058] Table 4 Experimental results and ranking of improvement effects

[0059]

[0060] Comprehensive analysis of the experimental results of the above five treatments shows that the best addition amount after principal component analysis is the 15% treatment group, and the worst effect is the group without the addition of the improver. Although some indicators of the 20% treatment group are also good, from the comprehensive consideration of cost-effectiveness and effect, adding 15% is the best choice.

[0061] It should be noted that, in this article, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0062] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A saline-alkali soil conditioner based on two tailings-based composite organic matter, characterized in that: The saline-alkali soil conditioner is composed of iron tailings, molybdenum tailings, optimized earthworm castings organic matter, wood acetic acid and ammonium sulfate in a ratio of 10-25:5-20:5-10:1:

1.

2. A saline-alkali soil conditioner based on two tailings-based composite organic matter according to claim 1, characterized in that: The saline-alkali soil conditioner is composed of iron tailings, molybdenum tailings, optimized earthworm castings organic matter, wood acetic acid and ammonium sulfate in a ratio of 20:15:5:1:

1.

3. The saline-alkali soil conditioner based on two tailings-based composite organic matter according to claim 1, characterized in that: The optimized earthworm castings organic matter is prepared by mixing earthworm castings and organic matter in a ratio of 7:3, composting at a temperature not lower than 25° C. for not less than 5 days, and naturally drying to a moisture content not higher than 8%.

4. A method for preparing a saline-alkali soil conditioner based on two tailings-based composite organic matter as claimed in claim 2, characterized in that: The following steps are involved: S1. Preparation of optimized earthworm castings and organic matter: Mix earthworm castings and organic matter in a ratio of 7:3, compost at a temperature not lower than 25°C for not less than 5 days, dry to a moisture content of not more than 8%, and set aside; S2, iron tailings and molybdenum tailings are graded and screened, passed through a 200 sieve, and set aside; 20 parts of the screened iron tailings and 15 parts of the molybdenum tailings are respectively mixed with 1 part of wood acetic acid, sealed at 40-50°C for 24-48 hours, activated to obtain modified iron tailings and modified molybdenum tailings, and the modified iron tailings and modified molybdenum tailings are mixed to obtain mixed tailings; S3, fully mixing the mixed tailings with 5 parts of optimized earthworm castings organic matter, composting for 2-3 days at a temperature not lower than 25° C., to obtain a tailings-based organic matter complex with a water content of ≤8%; S4, grinding the tailings-based organic compound at 400-600 rpm for 2-4 hours to obtain a modified tailings-based organic compound; S5, mixing the modified tailings-based organic compound with 1 part of ammonium sulfate, placing in a stirrer and mixing thoroughly, the stirring speed is controlled at 150-300 rpm, the stirring time is 10-15 minutes, and the two tailings compounds are fully mixed; S6. The fully mixed two tailings complexes obtained in S5 are aged at a temperature not lower than 25° C. for 3-5 days to obtain a saline-alkali soil conditioner.

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