Method for preparing super-anti-hard water mineral source humic acid calcium fertilizer and humic acid calcium special fertilizer from calcium carbide slag and agricultural biomass

Abstract

The application provides a method for preparing super-anti-hard water mineral source humic acid calcium fertilizer and humic acid calcium special fertilizer from carbide slag and agricultural biomass, and utilizes typical industrial solid waste carbide slag to provide an alkaline environment and calcium elements for the low-temperature roasting process of agricultural biomass. The technical scheme can not only safely utilize carbide slag resources, reduce the dosage of medicines and operation and maintenance costs, but also enhance the catalytic performance through carbide slag coupling catalysts, reduce the loss of organic matter, and improve the carbon sequestration rate. In addition, the innovative method makes the low-temperature roasting process of agricultural biomass produce more small-molecule humic acid, solves the problem that the filter residue cannot be fully utilized in the previous method, and realizes the full resource utilization of the biomass. At the same time, the super-mineral source humic acid calcium liquid fertilizer and humic acid calcium special fertilizer with anti-hard water property are obtained, and the agricultural biomass and industrial solid waste are synergistically utilized.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste and agricultural biomass resource utilization technology, specifically to a method for producing super hard water resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer by co-producing calcium carbide slag with agricultural biomass. Technical Background

[0002] In recent years, with the promotion and development of agricultural technology, my country has become the world's largest producer of wheat, rice, and corn. However, soil degradation is hindering the sustainable development of my country's agriculture. Soil degradation is mainly caused by the loss of soil organic matter due to over-farming, pollution, or climate change, thereby damaging the soil's ecological functions, including soil acidification, mineral loss, reduced aggregate stability, and decreased water retention and fertilizer efficiency. The results of the Third National Soil Survey show that the average organic matter content of my country's soils has decreased by 31%, and low- and medium-yield fields account for more than 68% of the total cultivated land area. Meanwhile, non-grain agricultural biomass is a rich source of organic matter. Currently, my country's non-grain agricultural biomass production exceeds 960 million tons. Returning this agricultural biomass to the field is an effective way to replenish soil organic matter and utilize biomass resources. However, because agricultural biomass contains a large amount of sugar, direct return to the field can easily lead to bacterial growth. Furthermore, the frozen soil period in Northeast my country, a major agricultural production area, prevents the straw from fully decomposing after being returned to the field, causing difficulties for spring sowing. Therefore, agricultural biomass needs to be pre-treated before being returned to the field.

[0003] Currently, the main pretreatment methods for agricultural biomass before returning it to the field include composting, fermentation, and thermochemical treatment. Composting and fermentation, besides potentially producing methane from the degradation of organic matter, also release large amounts of greenhouse gases such as carbon dioxide, ammonia, and nitrogen oxides. Furthermore, composting and fermentation have long cycles, typically exceeding 90 days, making them inefficient for processing large quantities of agricultural biomass. Thermochemical treatment mainly utilizes processes such as pyrolysis, hydrothermal treatment, or calcination to convert biomass into biochar or humic acid. Biochar is a solid carbon-rich material that can significantly improve soil properties when applied. However, large-scale application of biochar generates substantial dust, and its preparation process is energy-intensive and relatively costly. In recent years, researchers have discovered that applying endogenous organic humic acid substances to the soil can better restore its ecological functions. Therefore, the production of humic acid fertilizer from biomass at low temperatures has become a research hotspot. Examples include: a method for preparing water-soluble fertilizer containing ultra-mineralized humic acid from agricultural and forestry biomass solid waste (ZL2022113443712); and a method for preparing potassium humate and biochar from agricultural and forestry waste (ZL202110560969.4). Compared to traditional hydrothermal biomass production of humic acid fertilizer, these methods have advantages such as low energy consumption, simple processes, and low equipment requirements. However, the activators and alkalis used in these inventions are often expensive, and most of the products are large-molecule humic acids that are difficult for plants to directly utilize, limiting the effectiveness and economic viability of the corresponding humic acid fertilizer products. Furthermore, they lack consideration for the full resource utilization of the residue. Therefore, it is necessary to find a low-cost alternative to the alkali source and to attempt to achieve resource utilization of the residue.

[0004] Carbide slag is a major industrial solid waste, and its effective resource utilization and harmless treatment remain a major bottleneck for the development of the chlor-alkali industry. Currently, the main ways to utilize carbide slag are in construction materials, the preparation of calcium-based chemical products, and flue gas desulfurization. However, these methods suffer from problems such as poor product stability, complex processes, and the risk of secondary pollution. The harmfulness of carbide slag mainly lies in its high content of alkaline metal oxides such as calcium, sodium, and aluminum, which readily react with water to produce a strongly alkaline solution, causing irritation, corrosion, and burns to the human body. However, this property also makes it a promising alternative alkali source, providing a suitable reaction environment for the roasting of agricultural biomass to produce humic acid fertilizer, and offering a new direction for the resource utilization of carbide slag. Summary of the Invention

[0005] This invention aims to solve the problems existing in the process of agricultural biomass resource utilization, and proposes a method for producing super hard water resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer by synergistic use of carbide slag and agricultural biomass.

[0006] To achieve the objective of this invention, this invention provides a method for producing super-hard water-resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer using carbide slag in conjunction with agricultural biomass, comprising the following steps:

[0007] 1) Add carbide slag and catalyst to agricultural biomass, add water and mix evenly, dry after reaction to obtain carbide slag-catalyst-biomass mixture;

[0008] 2) The mixture obtained in step 1) is placed in an air atmosphere for pyrolysis, and the pyrolysis residue is obtained after cooling;

[0009] 3) Add water to the pyrolysis residue obtained in step 2), mix evenly, and filter to obtain the liquid, which is the super hard water resistant mineral humic acid calcium fertilizer.

[0010] 4) Dry the filter residue after filtration in step 3) to obtain the calcium humate special fertilizer.

[0011] Preferably, in step 1), the catalyst is a transition metal oxide; the mass percentage of alkali metals in the carbide slag is: calcium 50-70%, sodium 1-5%, aluminum 1-5%, silicon 1-10%; the particle size distribution is 0.5-30 μm; and the agricultural biomass is corn stalks or cotton stalks.

[0012] Preferably, in step 1), the catalyst is iron oxide or nickel oxide; the mass of the catalyst added is 0.1-1% of the dry weight of agricultural biomass, the mass of carbide slag added is 5-15% of the dry weight of agricultural biomass, and the ratio of the mass of water added to the dry weight of biomass is 0.8-1.2:1.

[0013] Preferably, in step 1), the carbide slag, catalyst, and agricultural biomass are mixed evenly at a stirring rate of 100-200 rpm; the reaction time is 0.5 ± 0.2 h; and the drying temperature is 80 ± 5 °C until the weight of the mixture no longer changes.

[0014] Preferably, in step 2), the pyrolysis temperature is 250±50℃ and the pyrolysis time is 2±0.5h.

[0015] Preferably, in step 3), the ratio of the mass of water added to the dry weight of the pyrolysis residue is 0.8 to 1.2:1; the pyrolysis residue and water are mixed evenly under a stirring speed of 100 to 200 rpm.

[0016] Preferably, in step 4), the drying temperature is 80±5℃ until the weight of the calcium humate special fertilizer no longer changes.

[0017] The present invention also provides a super hard water resistant mineral-derived calcium humate fertilizer prepared by the above method.

[0018] The present invention also provides a special fertilizer of calcium humate prepared by the above method.

[0019] This invention also provides an application of the above-mentioned super hard water resistant mineral-derived calcium humate fertilizer and / or the special calcium humate fertilizer of claim 9 in the field of soil conditioning.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] (1) The method of this invention fully utilizes the alkali metal elements and strong alkalinity abundant in carbide slag, providing an alkaline environment and calcium element for the low-temperature roasting of agricultural biomass to produce humic acid fertilizer, safely utilizing carbide slag as a resource, and reducing the amount of chemicals used and operation and maintenance costs. In addition, by combining carbide slag with transition metal catalysts, the catalytic performance is enhanced, the loss of organic matter is reduced, and the carbon sequestration rate is improved; the low-temperature roasting process promotes the humification of agricultural biomass to produce humic acid substances and increases the yield of small molecule fulvic acid. Based on the difference in solubility between calcium fulvicate and calcium humate, calcium fulvicate liquid fertilizer and calcium humate special fertilizer are obtained by water leaching and filtration separation of the products, which improves the problem of not being able to fully utilize the filter residue in previous methods, thereby realizing the full resource utilization of biomass and the synergistic resource utilization of agricultural biomass and industrial solid waste.

[0022] (2) The calcium humate liquid fertilizer prepared by this invention has excellent resistance to hard water and the ability to stimulate plant growth. It can be used for drip irrigation or compounded with pesticides to demonstrate resistance to hard water and has excellent effect on stimulating plant growth. The calcium humate special fertilizer is rich in calcium and has strong pH buffering capacity and water retention capacity. It can be used for planting plants such as cotton that require a lot of calcium, as well as for soil acidification treatment or desert water retention agent. It has the ability to improve soil structure, alleviate soil acidification and enhance water retention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used will be briefly described below. It should be noted that the following description of the drawings is merely some embodiments of the present invention, and those skilled in the art can obtain other related drawings based on these drawings without any creative effort.

[0024] Figure 1 This is a flowchart of the present invention.

[0025] Figure 2 The mixture of carbide slag, catalyst, and biomass after pyrolysis catalysis in Example 1 is shown.

[0026] Figure 3 XRD pattern of carbide slag as described in section 1.

[0027] Figure 4 The growth chart of the bok choy in Test Example 4 over three weeks. Detailed Implementation

[0028] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0029] Example 1:

[0030] The agricultural biomass used in this embodiment is corn straw. The XRF elemental analysis results of the carbide slag are shown in Table 1, the basic physicochemical properties of the corn straw are shown in Table 2, and the XRD pattern of the carbide slag is shown in... Figure 3 As shown.

[0031] Table 1. XRF elemental analysis results of calcium carbide slag in Example 1

[0032] Mo 1.14 Na 1.36 Fe 2.12 S 1.11 Al 2.47 Si 1.36 Ca 68.75

[0033] Table 2. Basic physicochemical properties of corn stalks in Example 1

[0034] Organic matter content 96.24％ Ca 0.52％ N 0.61％ P 0.43％ K 1.67％

[0035] 1) Take 250g of corn stalks into a 1L beaker, add 0.25g of nano iron oxide (0.1% of the dry weight of biomass) and 12.5g of carbide slag (5% of the dry weight of biomass), add 250mL of water and mix evenly with a magnetic stirrer at a stirring speed of 200rpm. After reacting for 0.7h, place it in an 80℃ oven until the weight no longer changes, and obtain a carbide slag-catalyst-biomass mixture.

[0036] 2) Place the mixture obtained in step 1) in an air atmosphere oven and pyrolyze it at 280°C for 2.5 h. After cooling, obtain the pyrolysis residue.

[0037] The pyrolysis residue obtained in step 2) is as follows Figure 2 As shown.

[0038] 3) Add 233.29 mL of water (1:1 mass of water to the pyrolysis residue obtained in step 2) and mix evenly with a magnetic stirrer at a stirring speed of 200 rpm. After filtering the solid-liquid mixture, the resulting liquid is a super hard water resistant mineral-derived calcium humate fertilizer.

[0039] 4) Place the filter residue from step 3) in an 80℃ oven until its weight no longer changes, and you will get calcium humate special fertilizer.

[0040] Example 2:

[0041] The method described in Example 1 is used to produce super-hard water resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer through catalytic pyrolysis of calcium carbide slag-assisted agricultural biomass. The only difference is that in step 1), 2.5g of nano-iron oxide (1% of the dry weight of biomass) and 25g of calcium carbide slag (10% of the dry weight of biomass) are added and mixed evenly with a magnetic stirrer at a stirring speed of 100rpm. After reacting for 0.3h, the mixture is placed in a 75℃ oven until the weight no longer changes, resulting in a calcium carbide slag-catalyst-biomass mixture. In step 2), the pyrolysis conditions in the oven are pyrolysis at 220℃ for 1.5h, and the pyrolysis residue is obtained after cooling. In step 3), 198.55mL of water (0.8:1 by mass of the residue) is added to the pyrolysis residue obtained in step 2) and mixed evenly with a magnetic stirrer at a stirring speed of 100rpm. In step 4), the mixture is placed in a 75℃ oven until the weight no longer changes.

[0042] Example 3:

[0043] The method described in Example 1 is used to produce super-hard water resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer through catalytic pyrolysis of calcium carbide slag-assisted agricultural biomass. The only difference is that in step 1), 1.25g of nano-nickel oxide (0.5% of the dry weight of biomass) and 37.5g of calcium carbide slag (15% of the dry weight of biomass) are added and mixed evenly with a magnetic stirrer at a stirring speed of 150rpm. After reacting for 0.5h, the mixture is placed in an 85℃ oven until the weight no longer changes, resulting in a calcium carbide slag-catalyst-biomass mixture. In step 2), the pyrolysis conditions in the oven are pyrolysis at 250℃ for 2h, and the pyrolysis residue is obtained after cooling. In step 3), 310.8mL of water (1.2:1 by mass of the residue) is added to the pyrolysis residue obtained in step 2) and mixed evenly with a magnetic stirrer at a stirring speed of 150rpm. In step 4), the mixture is placed in an 85℃ oven until the weight no longer changes.

[0044] Comparative Example 1:

[0045] The method described in Example 1 is used to produce super hard water resistant mineral humic acid calcium fertilizer and humic acid calcium special fertilizer by catalytic pyrolysis of agricultural biomass assisted by carbide slag, with the only difference being that nano iron oxide is not added in step 1).

[0046] Comparative Example 2:

[0047] The method described in Example 1 is used to produce super hard water resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer by catalytic pyrolysis of agricultural biomass assisted by carbide slag, the only difference being that carbide slag is not added in step 1).

[0048] Comparative Example 3:

[0049] The method described in Example 1 is used to produce super hard water resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer by catalytic pyrolysis of agricultural biomass assisted by carbide slag. The only difference is that nano iron oxide and carbide slag are not added in step 1).

[0050] Test Example 1:

[0051] The pyrolysis residues obtained in step 2) of each embodiment and comparative example were subjected to humic acid (including fulvic acid) content determination and humic acid yield calculation.

[0052] 1) Determine the humic acid content in the pyrolysis residue according to the standard method provided in NY-T 1971-2010.

[0053] 2) Calculate the humic acid yield of biomass catalytic pyrolysis according to the formula: Humic acid yield = (measured humic acid content (g) / 250) × 100%.

[0054] The humic acid yields of each embodiment and comparative example are shown in Table 3.

[0055] Table 3 Humic acid yield of each example and each comparative example

[0056]

[0057] As shown in Table 3, the technical solution described in this invention can achieve efficient humification of biomass.

[0058] Test Example 2:

[0059] The humic acid content of the pyrolysis residues obtained in step 2) of each embodiment and comparative example was determined, and the humic acid yield was calculated.

[0060] 1) Determine the humic acid content in the pyrolysis residue according to the standard method provided in NY / T 3162-2017.

[0061] 2) Calculate the humic acid yield of biomass catalytic pyrolysis according to the formula: Humic acid yield = (measured humic acid content (g) / 250) × 100%.

[0062] The humic acid yields of each embodiment and comparative example are shown in Table 4.

[0063] Table 4. Furic acid yield of each example and comparative example

[0064]

[0065] As shown in Table 4, the technical solution described in this invention can improve the catalytic effect of the catalyst, generate more small-molecule humic acid, and improve economic benefits.

[0066] Test Example 3:

[0067] The hard water resistance of the calcium humate fertilizer in each example and comparative example was determined, and the determination steps are as follows:

[0068] 1) The calcium humate fertilizer obtained in step 2) was diluted with hard water at a mass ratio of 1:30. The water hardness was 35 degrees. The results are shown in Table 5.

[0069] Table 5. Hard water resistance of calcium humate fertilizer in each example and comparative example.

[0070]

[0071] As shown in Table 5, the technical solution described in this invention can significantly improve the hard water resistance of calcium humate fertilizer, and can be used in drip irrigation or in combination with pesticides, etc., to demonstrate the ability to resist hard water.

[0072] Test Example 4:

[0073] Pot culture experiments were conducted on the calcium humate fertilizer and calcium humate special fertilizer used in each embodiment and comparative example to determine their effects on improving plants and soil. The steps are as follows:

[0074] 1) Pot experiments were conducted using raw soil obtained from below 30cm in depth as the substrate. Each pot contained 5kg of raw soil and 50mL of calcium humate fertilizer or 50g of calcium humate special fertilizer, and was thoroughly watered with tap water. The physicochemical properties of the raw soil used in this test example are shown in Table 6.

[0075] Table 6 shows the physical and chemical properties of the raw soil used in Test Example 4.

[0076] pH 4.92 TN (g / kg) 0.65 TP (g / kg) 0.23 TK(g / kg) 6.2 TOC (g / kg) 8.66 CEC (cmol / kg) 4.6

[0077] 2) After the potting soil in the pot has dried properly, evenly sprinkle 30 small Chinese cabbage seeds (Jingfeng No. 1) into the soil, and control the watering amount to 100mL per day.

[0078] Three weeks later, the plant growth in pots using the nutrient soil obtained in each example and comparative example as the substrate is as follows: Figure 4 As shown (5 plants are randomly selected from each group).

[0079] Depend on Figure 4 The growth of the bok choy shown indicates that the calcium humate fertilizer or calcium humate special fertilizer provided by the technical solution of the present invention can significantly promote the growth of bok choy.

[0080] After harvest, soil samples were taken from each group for analysis, and the results are shown in Table 7.

[0081] Table 7. Physicochemical properties of potted plants grown in nutrient soil after three weeks in each embodiment and comparative example.

[0082]

[0083]

[0084] *H: Application of calcium humate fertilizer; F: Application of special calcium humate fertilizer

[0085] *Water retention test index: After the soil of the potted plant test is sampled and air-dried, 10g of the air-dried soil is mixed with water at a mass ratio of 1:1 to prepare soil with 100% moisture content. The remaining soil moisture content is measured after the soil is placed in a 40℃ oven for 2 hours.

[0086] The physicochemical properties of the post-harvest nutrient soil shown in Table 7 indicate that the nutrient soil obtained by the technical solution described in this invention can significantly alleviate the acidification of the substrate soil, while improving soil water retention and reducing nutrient loss.

[0087] The results of Test Example 4 show that applying calcium humate fertilizer is effective in increasing soil CEC and enhancing soil fertility; applying calcium humate special fertilizer is effective in improving soil structure, increasing organic matter content, and enhancing water retention. In practical applications, combined application can be considered to achieve the best results.

[0088] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for producing super-hard water-resistant mineral-derived calcium humate fertilizer and calcium humate special fertilizer from calcium carbide slag in synergistic agricultural biomass production, characterized in that, Includes the following steps: 1) Add carbide slag and catalyst to agricultural biomass, add water and mix evenly, dry after reaction to obtain carbide slag-catalyst-biomass mixture; in step 1), the catalyst is iron oxide or nickel oxide; the mass percentage of alkali metals in the carbide slag is: calcium 50~70%, sodium 1~5%, aluminum 1~5%, silicon 1~10%; the particle size distribution is 0.5~30μm; the agricultural biomass is corn stalk or cotton stalk; the mass of catalyst added is 0.1~1% of the dry weight of agricultural biomass, the mass of carbide slag added is 5~15% of the dry weight of agricultural biomass, and the ratio of the mass of water added to the dry weight of biomass is 0.8~1.2:1; 2) The mixture obtained in step 1) is placed in an air atmosphere for pyrolysis, and after cooling, pyrolysis residue is obtained; in step 2), the pyrolysis temperature is 250±50℃, and the pyrolysis time is 2±0.5h; 3) Add water to the pyrolysis residue obtained in step 2), mix evenly, and filter to obtain the liquid, which is the super hard water resistant mineral humic acid calcium fertilizer. 4) Dry the filter residue after filtration in step 3) to obtain the calcium humate special fertilizer.

2. The method according to claim 1, characterized in that, In step 1), the carbide slag, catalyst, and agricultural biomass are mixed evenly at a stirring rate of 100-200 rpm; The reaction time was 0.5 ± 0.2 h; The drying temperature is 80±5℃ until the weight of the mixture no longer changes.

3. The method according to claim 1, characterized in that, In step 3), the ratio of the mass of water added to the dry weight of the pyrolysis residue is 0.8~1.2:1; the pyrolysis residue and water are mixed evenly under a stirring speed of 100~200 rpm.

4. The method according to claim 1, characterized in that, In step 4), the drying temperature is 80±5℃ until the weight of the calcium humate special fertilizer no longer changes.

5. A super hard water resistant mineral-derived calcium humate fertilizer prepared by any one of claims 1 to 4.

6. A special fertilizer of calcium humate prepared by any one of claims 1 to 4.

7. The application of the super hard water resistant mineral-derived calcium humate fertilizer of claim 5 and / or the special calcium humate fertilizer of claim 6 in the field of soil conditioning.

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