Iron-silicon composite organic fertilizer prepared by activating iron tailings with acid and method thereof

Abstract

This invention provides a method for preparing an iron-silicon composite organic fertilizer using acid-activated iron tailings. The method involves crushing high-silicon iron tailings through a 200-mesh sieve, mixing it with an acid activator composed of citric acid and oxalic acid in a specific ratio, aging it in water for 25-30 days, and then drying it to obtain acid-activated iron tailings. This is then mixed with livestock manure (20-45 parts), crop residues (15-40 parts), microbial agents (1-2 parts), and water (10-30 parts), and composted in windrows for 40-50 days before drying to obtain the finished organic fertilizer. This process is simple, low-cost, and energy-efficient, realizing the resource utilization of iron tailings solid waste. The resulting fertilizer is rich in soluble silicon and iron, can complex with humic acid, and is suitable for silicon-loving, acid-loving, and iron-loving crops. It promotes growth, increases yield, and improves quality, and can be used as a base fertilizer or top dressing.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, and more specifically, to an iron-silicon composite organic fertilizer prepared by acid-activated iron tailings and its method. Background Technology

[0002] Silicon fertilizer refers to fertilizers containing a high concentration of silicon, primarily made from silicate minerals, diatoms, and siliceous limestone. Silicon plays a vital role in plant growth, and the demand for silicon fertilizer in agricultural production is increasing, indicating a promising market prospect. With the advancement of agricultural modernization in China and the continuous improvement of people's requirements for food quality, silicon fertilizer, as a new type of environmentally friendly green fertilizer, has become an important area of ​​modern agricultural development.

[0003] Silicon fertilizer has a significant effect on improving crop quality, increasing yield, and enhancing stress resistance, and can be widely used in the production of various crops such as rice, wheat, corn, vegetables, and fruits. With the acceleration of urbanization, some farmland has been used for urban construction, leading to a decline in soil fertility and restricting crop growth. Therefore, it is necessary to introduce new fertilizers such as silicon fertilizer to supplement the soil, which has also promoted the development of the silicon fertilizer market.

[0004] Currently, there are 258 publicly disclosed invention patents related to silicon fertilizer, mainly focusing on processing silicon-containing solid waste as the main raw material to obtain agricultural silicon fertilizer. The processing techniques primarily involve crushing and screening, high-temperature calcination, and alkaline activation. For example, application number 2023114267318 describes a method for preparing silicon fertilizer using high-silicon iron tailings. This involves adding an alkaline activator and a calcium-containing activator to the iron tailings, followed by ultrasonic treatment and hydrothermal reaction to obtain the silicon fertilizer. Application number 2023110836292 describes a water-soluble silicon fertilizer and its application, which uses quartz stone calcined at 2000-2600℃ and then mixed with water to obtain water-soluble silicon fertilizer. However, processing techniques such as crushing and screening, and high-temperature calcination are energy-intensive and have high carbon emissions; and alkaline-activated silicon fertilizer is not suitable for acid-loving crops.

[0005] Iron ranks fourth in abundance in the Earth's crust and has high redox properties. Iron is an important mineral micronutrient for plant growth and development, influencing photosynthesis and respiration. Cytochrome oxidase, nitrogenase, and catalase in plants all contain iron, indicating that iron significantly affects nutrient cycling in agro-ecosystems.

[0006] In agricultural production, two types of fertilizers are commonly used: inorganic iron fertilizer and organic iron fertilizer. Inorganic iron fertilizer is mainly in the form of ferrous sulfate, which is easily oxidized and precipitated, resulting in low effectiveness and poor fertilizer efficiency, leading to a gradual decrease in utilization rate. Organic iron fertilizer is a new type of bio-organic fertilizer with multiple functions, including comprehensive nutrition, promotion of plant growth, soil improvement, promotion of soil microbial activity, and slow-release effect. Currently, in my country's farmland, 31% of the soil is iron deficient. Insufficient iron nutrient supply is a major cause of soil infertility and crop growth degradation, and organic iron fertilizer is an effective means to solve this problem. The main components of organic iron fertilizer include organic matter and iron. Common organic fertilizers include well-rotted animal manure, crop residues, and household kitchen waste. Iron usually exists in the form of chelates or complexes, which can stabilize iron ions, making them easier for plants to absorb and slowing down the release rate of iron.

[0007] Currently, only six invention patents related to iron-rich organic fertilizers have been published. These mainly focus on preparing iron-rich organic fertilizers using chemical processes, which suffer from drawbacks such as complex processes and high energy consumption. Alternatively, they involve adding inorganic iron salts such as ferrous sulfate and ferric sulfate during organic matter fermentation. These inorganic iron salts are industrial raw materials, and their preparation and processing costs are high, resulting in high raw material costs for iron-rich organic fertilizers. For example, application number 2015110168361 utilizes materials such as tea residue, humic acid paste, sodium iron ethylenediaminetetraacetate, cow dung, sucrose, sodium dodecyl sulfate, potassium carbonate, nano-carbon black, household organic waste, and citric acid, requiring heating, high-temperature calcination, stirring, and dehydration processes based on composting fermentation. Application number 2016106077364 utilizes traditional Chinese medicine, rapeseed cake, cottonseed cake, soybean cake, and sesame cake, fermented in the presence of Gram-positive actinomycetes, and then mixed with ferrous gluconate, potassium ore powder, and phosphate rock powder to prepare iron-rich organic fertilizer. Application No. 2014103588053 describes the production of iron-rich organic fertilizer through fermentation of tea residue, cow dung, sucrose, a decomposing agent, and ferrous sulfate. Application No. 2015109759375 describes the production of iron-rich organic fertilizer through mixed fermentation of chicken manure, sawdust, rice husks, and ferrous sulfate. Therefore, reducing the raw material cost of iron-rich organic fertilizer and simplifying the preparation process are key to its research and development. To address this, we propose an improvement: a method for preparing an iron-silicon composite organic fertilizer using acid-activated iron tailings. Summary of the Invention

[0008] The purpose of this invention is to utilize acid-activated iron tailings, livestock and poultry manure, and agricultural residues for mixed composting. The acid-activated iron tailings provide both silicon and iron sources, while the organic acids produced during the fermentation of the livestock and poultry manure and agricultural residues undergo a complexation reaction with the iron source to prepare a novel iron-silicon composite organic fertilizer. This invention not only achieves the resource utilization of iron tailings solid waste but also effectively reduces raw material costs and simplifies the process, thereby reducing the economic pressure on crop cultivation while utilizing waste.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: an iron-silicon composite organic fertilizer prepared using acid-activated iron tailings and its method. The iron-silicon composite organic fertilizer prepared using acid-activated iron tailings comprises, by weight: 20-45 parts of livestock and poultry manure, 15-40 parts of crop residue, 1-10 parts of acid-activated iron tailings, 1-2 parts of microbial agent, and 10-30 parts of water.

[0010] As a preferred technical solution of the present invention, the livestock and poultry manure is one or more of the following: cow manure, chicken manure, pig manure, sheep manure, horse manure, and duck manure.

[0011] As a preferred technical solution of the present invention, the crop residue is one or more of rice straw, wheat straw, and corn stalks.

[0012] As a preferred technical solution of the present invention, the acid-activated iron tailings are obtained by crushing high-silicon iron tailings, mixing them with an acid activator, aging them, and then drying them.

[0013] As a preferred technical solution of the present invention, the high-silicon iron tailings has a silica content of 65% to 85%, a total iron content of 8% to 20%, and an iron oxide content of 4% to 10%.

[0014] Preferably, the acid activator raw materials are citric acid and oxalic acid. Citric acid and oxalic acid are low molecular weight organic acids, which have a good activation effect on mineral acids. Compared with inorganic acids such as sulfuric acid, they avoid the disadvantages of being environmentally unfriendly due to high concentrations.

[0015] As a preferred embodiment of the present invention, the mass ratio of citric acid to oxalic acid in the acid activator is 1:(1-1.2).

[0016] As a preferred technical solution of the present invention, the bacterial agent is one or more of Bacillus subtilis, Pseudomonas phosphate-solubilizing bacteria, lactic acid bacteria, and yeast.

[0017] On the other hand, a method for preparing the above-mentioned iron-silicon composite organic fertilizer is also provided, which includes the following steps: Preparation of acid-activated iron tailings: The iron tailings are crushed and passed through a 200-mesh sieve to obtain iron tailings powder.

[0018] Iron tailings powder and acid activator are mixed in a weight ratio of 10:(3-4) to obtain a mixture.

[0019] Water is added to the mixture at a solid-liquid ratio of 1:(2.5-3.2), stirred, and allowed to stand for aging for 25-30 days before drying to obtain acid-activated iron tailings.

[0020] Material preparation: Weigh the materials according to the following weight parts: 20-45 parts of livestock and poultry manure, 15-40 parts of agricultural residue, 1-10 parts of acid-activated iron tailings, and 1-2 parts of microbial agent.

[0021] Mixing and adding water: Mix all materials evenly, add 10 to 30 parts of water to adjust the moisture content of the materials to 50% to 65%.

[0022] Composting: The mixed materials are piled in windrows and allowed to ferment naturally in an outdoor environment where the temperature is above 10℃. Initially, the compost pile is turned every 2-3 days; once the fermentation temperature exceeds 50℃, it is turned daily; once the fermentation temperature falls below 50℃ and stops rising, it is turned every 2-3 days. A suitable amount of moisture is added each time the pile is turned. Fermentation is complete after 40-50 days when the fermentation temperature and moisture content remain constant.

[0023] Natural air drying: The fermented material is naturally air dried until the moisture content is between 25% and 35% to obtain iron-silicon compound organic fertilizer.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The acid-activated iron tailings added in this invention improve the porosity of the organic material fermentation pile, enhance its aeration, and provide sufficient oxygen to support the growth and reproduction of microorganisms, as well as aid in the decomposition of organic matter, thereby increasing nutrient release efficiency and shortening fermentation time. During composting fermentation, the humic acid produced from the decomposition of organic matter undergoes a complexation reaction with the iron elements in the iron tailings. The resulting iron complex slows down the release rate of iron, and the soluble iron ions are more easily absorbed by plants, thus promoting plant growth and development.

[0025] This invention uses widely available raw materials, has a simple preparation process, low cost, and low energy consumption. It effectively utilizes the silicon and iron elements abundant in iron tailings to achieve the resource utilization of iron tailings.

[0026] The iron-silicon composite organic fertilizer produced by this invention is suitable for crops that prefer silicon, acid, and iron. It can be used as a base fertilizer or as a top dressing. Attached image description: Figure 1 This is a schematic diagram of the preparation process of the iron-silicon composite organic fertilizer provided by the present invention; Figure 2 This is a schematic diagram of the acid-activated iron tailings preparation process provided by the present invention; Figure 3 The schematic diagram of the XRD characterization structure of iron tailings and acid-activated iron tailings provided by the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are specific implementations of the present invention and are not limited to all embodiments.

[0028] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] Example 1: An iron-silicon composite organic fertilizer prepared using acid-activated iron tailings and its method. The iron-silicon composite organic fertilizer prepared using acid-activated iron tailings comprises, by weight: 20-45 parts of livestock and poultry manure, 15-40 parts of crop residue, 1-10 parts of acid-activated iron tailings, 1-2 parts of microbial agent, and 10-30 parts of water.

[0031] Livestock and poultry manure includes one or more of the following: cow manure, chicken manure, pig manure, sheep manure, horse manure, and duck manure.

[0032] Agricultural residues are one or more of rice straw, wheat straw, and corn stalks.

[0033] Acid-activated iron tailings are obtained by crushing high-silicon iron tailings, mixing them with an acid activator, aging them, and then drying them.

[0034] The high-silicon iron tailings have a silica content of 65%–85%, a total iron content of 8%–20%, and an iron oxide content of 4%–10%.

[0035] Preferably, the acid activator raw materials are citric acid and oxalic acid. Citric acid and oxalic acid are low molecular weight organic acids, which have a good activation effect on mineral acids. Compared with inorganic acids such as sulfuric acid, they avoid the disadvantages of being environmentally unfriendly due to high concentrations.

[0036] The mass ratio of citric acid to oxalic acid in the acid activator is 1:(1~1.2).

[0037] The inoculant is one or more of Bacillus subtilis, Pseudomonas phosphate-solubilizing bacteria, lactic acid bacteria, and yeast.

[0038] On the other hand, a method for preparing the above-mentioned iron-silicon composite organic fertilizer is also provided, which includes the following steps: Preparation of acid-activated iron tailings: The iron tailings are crushed and passed through a 200-mesh sieve to obtain iron tailings powder.

[0039] Iron tailings powder and acid activator are mixed in a weight ratio of 10:(3-4) to obtain a mixture.

[0040] Water is added to the mixture at a solid-liquid ratio of 1:(2.5-3.2), stirred, and allowed to stand for aging for 25-30 days before drying to obtain acid-activated iron tailings.

[0041] Material preparation: Weigh the materials according to the following weight parts: 20-45 parts of livestock and poultry manure, 15-40 parts of agricultural residue, 1-10 parts of acid-activated iron tailings, and 1-2 parts of microbial agent.

[0042] Mixing and adding water: Mix all materials evenly, add 10 to 30 parts of water to adjust the moisture content of the materials to 50% to 65%.

[0043] Composting: The mixed materials are piled in windrows and allowed to ferment naturally in an outdoor environment where the temperature is above 10℃. Initially, the compost pile is turned every 2-3 days; once the fermentation temperature exceeds 50℃, it is turned daily; once the fermentation temperature falls below 50℃ and stops rising, it is turned every 2-3 days. A suitable amount of moisture is added each time the pile is turned. Fermentation is complete after 40-50 days when the fermentation temperature and moisture content remain constant.

[0044] Natural air drying: The fermented material is naturally air dried until the moisture content is between 25% and 35% to obtain iron-silicon compound organic fertilizer.

[0045] Example 2: This invention provides an acid-activated iron tailings solution, comprising the following steps: After crushing the high-silicon iron tailings, mixing them with an acid activator, aging them, and then drying them, acid-activated iron tailings are obtained.

[0046] In a preferred embodiment of the present invention, the silica content of the high-silicon iron tailings is 70% to 80%.

[0047] In a preferred embodiment of the present invention, the acid activator is citric acid and oxalic acid, both with a purity of 99.5%.

[0048] In a preferred embodiment of the present invention, the mass ratio of citric acid to oxalic acid in the acid activator is 1:1.

[0049] In a preferred embodiment of the present invention, the iron tailings are crushed and passed through a 200-mesh sieve to obtain iron tailings powder.

[0050] In a preferred embodiment of the present invention, iron tailings powder and acid activator are mixed in a weight ratio of 10:3 to obtain a mixture.

[0051] In a preferred embodiment of the present invention, water is added to the mixture at a solid-liquid ratio of 1:3, stirred, and allowed to stand for aging for 28 days, and then dried to obtain acid-activated iron tailings.

[0052] The high-silica iron tailings used in this embodiment of the invention are from a mining area in Anshan. The content of the main components in the iron tailings is shown in Table 1.

[0053] Table 1. Composition content of iron tailings.

[0054] The iron tailings were crushed and passed through a 200-mesh sieve. 500g of iron tailings powder was mixed with 150g of acid activator (75g of citric acid and 75g of oxalic acid in the acid activator), 1.95L of water was added, and the mixture was stirred for 10 minutes. The mixture was then allowed to stand and age for 28 days, and then dried at 105℃ to obtain acid-activated iron tailings.

[0055] XRD composition analysis was performed on iron tailings and acid-activated iron tailings, such as... Figure 3 As shown in the figure, the results indicate that the acid-activated iron tailings prepared by the present invention using iron tailings have higher purity of silicon as the main component.

[0056] Example 3: This embodiment provides an iron-silicon composite organic fertilizer prepared using acid-activated iron tailings, which, by weight, comprises: 38 parts fresh cow manure, 32 parts rice straw, 2 parts acid-activated iron tailings, and 1 part microbial agent.

[0057] The fresh cow dung had a moisture content of 79.2% and an organic matter content of 29.8%.

[0058] The organic matter content of the rice straw was 65.4%.

[0059] The acid-activated iron tailings are the acid-activated iron tailings obtained in Example 2.

[0060] The bacterial agent is Bacillus subtilis.

[0061] The preparation method of the above-mentioned iron-silicon composite organic fertilizer includes the following steps: Material preparation: Weigh the materials according to the following weight proportions: 38 parts fresh cow dung, 32 parts rice straw, 2 parts acid-activated iron tailings, and 1 part microbial agent.

[0062] Mix and add water: Mix all materials evenly, add 23 parts water to adjust the moisture content of the materials to about 55%.

[0063] Composting: The mixed materials are piled in windrows and allowed to ferment naturally at an outdoor temperature of 15℃. Initially, the compost pile is turned every 3 days; once the fermentation temperature exceeds 50℃, it is turned daily; once the fermentation temperature falls below 50℃ and stops rising, it is turned every 2 days. A suitable amount of moisture is added each time the pile is turned. Fermentation is complete in 45 days.

[0064] Natural air drying: When the fermented material is naturally air dried to a moisture content of 30%, iron-silicon compound organic fertilizer is obtained.

[0065] Fermentation effect evaluation: After the composting fermentation began, the temperature of the compost pile was recorded daily. Five samples were taken at regular intervals at a depth of 5-10 cm at three locations (front, middle, and back) of the pile to monitor changes in the pile's properties. The entire fermentation cycle consisted of four stages: heating up, high temperature, cooling down, and maturation.

[0066] The physicochemical properties of the iron-silicon composite organic fertilizer in the examples were measured, and all indicators met the standard "Organic Fertilizer" (NY / T 525-2021).

[0067] Table 2. Basic physicochemical properties of iron-silicon composite organic fertilizer.

[0068] Fertilizer efficacy test: Using purchased organic fertilizer as a control group, and the iron-silicon compound organic fertilizer described in the examples as a base fertilizer, the rice variety Tiannong 6 was selected for rice planting experiments. The fertilization amount and other planting management measures were kept consistent between the control group and the experimental group.

[0069] Sampling was conducted at the heading stage, and the quality of rice plants is shown in Table 3. The results showed that the rice plants fertilized with iron-silicon compound organic fertilizer had better quality.

[0070] Table 3. Rice plant quality in the experimental group and control group after application of iron-silicon compound organic fertilizer.

[0071] Actual yield measurements showed that, compared with purchased organic fertilizer, the iron-silicon composite organic fertilizer prepared in the example yielded an increase of 5.2%.

[0072] The above experimental results show that the iron-silicon composite organic fertilizer of the present invention was successfully prepared and has a promoting effect on the growth of rice plants.

[0073] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A type of iron-silicon composite organic fertilizer prepared using acid-activated iron tailings, characterized in that, By weight, it includes the following components: 20-45 parts of livestock and poultry manure, 15-40 parts of agricultural residue, 1-10 parts of acid-activated iron tailings, 1-2 parts of microbial agent, and 10-30 parts of water.

2. The iron-silicon composite organic fertilizer prepared using acid-activated iron tailings according to claim 1, characterized in that, The livestock and poultry manure is selected from one or more of the following: cow manure, chicken manure, pig manure, sheep manure, horse manure, and duck manure.

3. The iron-silicon composite organic fertilizer prepared using acid-activated iron tailings according to claim 1 or 2, characterized in that, The crop residues are selected from one or more of rice straw, wheat straw, and corn stalks.

4. A type of iron-silicon composite organic fertilizer prepared using acid-activated iron tailings according to any one of claims 1 to 3, characterized in that, The acid-activated iron tailings are obtained by acid activation treatment and drying of high-silicon iron tailings; the high-silicon iron tailings contain 65% to 85% silicon dioxide, 8% to 20% total iron, and 4% to 10% iron oxide.

5. The iron-silicon composite organic fertilizer prepared using acid-activated iron tailings according to claim 4, characterized in that, The acid activator used in the acid activation treatment is a mixture of citric acid and oxalic acid, wherein the mass ratio of citric acid to oxalic acid is 1:(1~1.2).

6. A type of iron-silicon composite organic fertilizer prepared using acid-activated iron tailings according to any one of claims 1 to 5, characterized in that, The microbial agent is selected from one or more of Bacillus subtilis, Pseudomonas phosphate-solubilizing bacteria, lactic acid bacteria, and yeast.

7. A method for preparing an iron-silicon composite organic fertilizer using acid-activated iron tailings according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step (1) Preparation of acid-activated iron tailings: crush high-silicon iron tailings through a 200-mesh sieve to obtain iron tailings powder; mix the iron tailings powder with acid activator at a weight ratio of 10:(3-4), then add water at a solid-liquid ratio of 1:(2.5-3.2), stir, let stand and age for 25-30 days, and dry to obtain acid-activated iron tailings; Step (2) Material mixing: Weigh 20-45 parts of livestock and poultry manure, 15-40 parts of agricultural residue, 1-10 parts of acid-activated iron tailings obtained in step (1), and 1-2 parts of microbial agent according to the ratio, and mix them evenly; Step (3) Adjusting moisture: Add 10-30 parts of water to make the moisture content of the mixture 50%-65%; Step (4) Composting: Stack the materials in windrows and allow them to ferment naturally at an ambient temperature above 10°C. In the early stages of composting, turn the pile every 2-3 days. When the temperature of the pile rises above 50°C, turn the pile once a day. When the temperature falls below 50°C and stops rising, resume turning the pile every 2-3 days and add water as needed each time the pile is turned. Continue fermenting for 40-50 days until the temperature and moisture content of the pile stabilize. Step (5) Natural drying: The fermented material is naturally dried until the moisture content is 25% to 35%, thus obtaining the iron-silicon composite organic fertilizer.

8. The method for preparing iron-silicon composite organic fertilizer using acid-activated iron tailings according to claim 7, characterized in that, The acid activator mentioned in step (1) is composed of citric acid and oxalic acid in a mass ratio of 1:(1 to 1.2).

9. The method for preparing iron-silicon composite organic fertilizer using acid-activated iron tailings according to claim 7, characterized in that, The livestock and poultry manure mentioned in step (2) is one or more of cow manure, chicken manure, pig manure, sheep manure, horse manure, and duck manure, and the agricultural residue is one or more of rice straw, wheat straw, and corn stalk.

10. The method for preparing iron-silicon composite organic fertilizer using acid-activated iron tailings according to any one of claims 7 to 9, characterized in that, The bacterial agent mentioned in step (2) is one or more of Bacillus subtilis, Pseudomonas phosphate-solubilizing bacteria, lactic acid bacteria, and yeast.

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