Phosphorus tailing and biomass composite soil conditioner and preparation method thereof

Abstract

The invention discloses a phosphate tailing and biomass composite soil conditioner and a preparation method thereof.In the preparation process, firstly, phosphate tailings are air-dried and sieved to obtain a phosphate tailing material, then agricultural waste is dried, smashed and sieved to obtain an agricultural waste material, biomass is subjected to anaerobic pyrolysis and then sieved to obtain a biochar material, and the biochar material is subjected to anaerobic pyrolysis and then sieved to obtain the phosphate tailing and biomass composite soil conditioner. And mixing the phosphate tailing material, the biochar material and the agricultural waste material in proportion, and performing microwave irradiation modification to obtain the composite soil conditioner. Phosphorus tailings are compounded with agricultural wastes such as straws, the agricultural wastes are modified by adopting an irradiation technology, the compound conditioner is developed, the toxicity of heavy metals in soil can be effectively reduced, the problems of deterioration of physical and chemical properties of soil in a metal mine area, poor soil structure, low soil biodiversity and the like are solved, and the survival rate of plants is increased.

Description

Technical Field

[0001] The invention relates to the technical field of soil improvement, and more particularly to a phosphate tailings and biomass composite soil conditioner and a preparation method thereof. Background Art

[0002] Phosphate tailings have become one of the industrial wastes with larger output. According to statistics, the utilization rate of phosphate tailings is only about 10%. The comprehensive utilization of tailings in 2020 was about 441 million tons, and the annual comprehensive utilization rate was about 34%, which is much lower than other bulk solid wastes; therefore, it is urgent to explore the comprehensive utilization methods of phosphate tailings. The comprehensive utilization of phosphate tailings can not only solve a series of problems such as resource waste, land occupation by tailings accumulation, and ecological environmental pollution, but also produce certain economic benefits. As a green industry, the resource utilization of tailings is an important breakthrough in turning waste into treasure, promoting benefits and eliminating disadvantages.

[0003] Phosphorus tailings contain phosphorus, magnesium, calcium, iron and other elements that are indispensable for the growth of crops. Therefore, applying phosphorus tailings to the agricultural field is an effective way to utilize phosphorus tailings as a resource. At present, the application of phosphorus tailings in the agricultural field in my country mainly includes phosphorus tailings reclamation, fertilizer production, preparation of soil conditioners and soil water retention agents. Although the technology of preparing fertilizers or soil conditioners from phosphorus tailings has been studied more in recent years, it has basically remained in the laboratory stage and has a high cost in actual application. Therefore, it is urgent to develop an efficient, low-cost method that can be promoted and applied. Summary of the invention

[0004] In view of this, the present invention provides a phosphate tailings and biomass composite soil conditioner and a preparation method thereof, which adopts phosphate tailings and agricultural wastes such as corn stalks as matrix materials, and modifies them by means of irradiation and the like, and through the cross-integration of multiple disciplines such as mineralogy, ecological environment, and materials science, while solving environmental problems in mining areas, reduces the cost of ecological restoration, promotes mine ecological restoration, and opens up a way to utilize phosphate tailings and agricultural waste as resources.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A method for preparing a composite soil conditioner of phosphate tailings and biomass comprises the following steps:

[0007] (1) air-drying and sieving the phosphate tailings to obtain a phosphate tailings material;

[0008] (2) drying, crushing and screening the agricultural waste to obtain agricultural waste materials;

[0009] (3) pyrolyzing the biomass at 500-600° C. for 4-6 hours without oxygen, and then sieving to obtain a biochar material;

[0010] (4) mixing the phosphate tailings material, the biochar material, and the agricultural waste material in a weight ratio of (1-5):(1-5):(1-5) to obtain a mixed material;

[0011] (5) The mixed material is modified by microwave irradiation to obtain a composite soil conditioner.

[0012] Preferably, in step (1), the product is sieved through an 80-mesh sieve.

[0013] Preferably, the agricultural waste in step (2) is one or more of corn stalks, peanut shells,

[0014] Preferably, in step (2), the product is sieved through a 20-mesh sieve.

[0015] Preferably, the biomass in step (3) is one or more of corn stalks and peanut shells.

[0016] Preferably, in step (3), the product is sieved through an 80-mesh sieve.

[0017] Preferably, in step (5), the microwave power is 950 W and the irradiation time is 10 to 30 min.

[0018] In addition, the present invention also provides a phosphate tailings and biomass composite soil conditioner prepared by the method described in the above technical solution.

[0019] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a phosphate tailings and biomass composite soil conditioner and a preparation method thereof, which has the following beneficial effects:

[0020] The present invention utilizes agricultural wastes such as phosphorus tailings and composite straw, and uses irradiation technology to modify them to develop a composite conditioner, which can effectively reduce the toxicity of heavy metals in the soil, solve the problems of deterioration of soil physical and chemical properties, poor soil structure, low soil biodiversity in metal mining areas, and improve plant survival rate. The materials selected by the method are easy to obtain, low in cost, and can effectively prevent secondary pollution and soil compaction, and have strong applicability and operability. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the following embodiments,

[0023] Phosphate tailings treatment method: air-dry the phosphate tailings and pass them through an 80-mesh sieve to obtain phosphate tailings materials;

[0024] The method for processing agricultural waste materials is as follows: drying and crushing corn stalks and peanut shells and passing through a 20-mesh sieve to obtain agricultural waste materials;

[0025] Preparation of biochar material: corn stalks and peanut shells are anaerobic pyrolyzed at 500-600° C. in a high-temperature electric furnace for 4-6 hours, and then sieved to produce biochar, which is then sieved through an 80-mesh sieve to obtain biochar material.

[0026] Example 1

[0027] The phosphate tailings material, the corn straw material and the biochar material are mixed in a weight ratio of 3:1:1 to obtain a mixed material;

[0028] The mixed material was irradiated for 15 minutes under a microwave power of 950 W to obtain an activated and modified composite soil conditioner product.

[0029] Example 2

[0030] The phosphate tailings material, the peanut shell material and the biochar material are mixed in a weight ratio of 3:1:1 to obtain a mixed material;

[0031] The mixed material was irradiated for 20 minutes under a microwave power of 950 W to obtain an activated and modified composite soil conditioner product.

[0032] Example 3

[0033] The phosphate tailings material, the corn straw and peanut shell mixture material and the biochar material are mixed in a weight ratio of 3:1:1 to obtain a mixed material;

[0034] The mixed material was irradiated for 30 minutes under a microwave power of 950 W to obtain an activated and modified composite soil conditioner product.

[0035] Comparative Example 1

[0036] The phosphate tailings material, the corn straw material and the biochar material are mixed in a weight ratio of 3:1:1 to obtain a mixed material;

[0037] No irradiation modification was performed.

[0038] Example 4

[0039] The phosphate tailings material, the corn straw and peanut shell mixture material and the biochar material are mixed in a weight ratio of 5:3:1 to obtain a mixed material;

[0040] The mixed material was irradiated for 30 minutes under a microwave power of 950 W to obtain an activated and modified composite soil conditioner product.

[0041] Example 5

[0042] The phosphate tailings material, the corn straw and peanut shell mixture material and the biochar material are mixed in a weight ratio of 5:4:2 to obtain a mixed material;

[0043] The mixed material was irradiated for 30 minutes under a microwave power of 950 W to obtain an activated and modified composite soil conditioner product.

[0044] Test example

[0045] This embodiment is a potted plant experiment.

[0046] The mining area soil after passing through a 20-mesh sieve was weighed and placed in a plastic flower pot, and the composite soil conditioner product produced in Comparative Example 1 and Example 4 was applied to the soil in an amount of 1.5% of the soil mass.

[0047] A blank test was arranged during the same period, i.e. no soil conditioner product was used.

[0048] After being thoroughly mixed, water was added to the experimental and control groups to maintain 65% of the maximum water holding capacity of the soil.

[0049] 40 ryegrass seeds that had been germinated were sown in the above soil, and the soil moisture content was maintained at about 65% by weighing and spraying water for 60 days. The germination rate, root length, seedling length, fresh weight, dry weight, and soil pH, organic matter content, and available state of heavy metals were measured.

[0050] The measurement results showed that the soil pH of the control group (blank group) was 5.05, the pH after applying the conditioner product of Comparative Example 1 (experimental group) was 7.52, and the pH after applying the conditioner product of Example 4 (experimental group) was 7.59, all of which significantly improved soil acidity; after applying the conditioner of Comparative Example 1, the germination rate was increased by 14% compared with the control, the root length was increased by 18% compared with the control, the seedling length was increased by 16% compared with the control, the fresh weight increase was increased by 17% compared with the control, the dry weight was increased by 8% compared with the control, the organic matter content was increased by 25% compared with the control, and the effective lead content was reduced by 30%.

[0051] After applying the conditioner of Example 4, the germination rate was increased by 15% compared with the control, the root length was increased by 10% compared with the control, the seedling length was increased by 20% compared with the control, the fresh weight increase was increased by 17% compared with the control, the dry weight was increased by 11% compared with the control, the organic matter content was increased by 30% compared with the control, and the effective lead content was reduced by 39%.

[0052] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0053] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a composite soil conditioner of phosphate tailings and biomass, characterized in that: The following steps are involved: (1) air-drying and sieving the phosphate tailings to obtain a phosphate tailings material; (2) drying, crushing and screening the agricultural waste to obtain agricultural waste materials; (3) pyrolyzing the biomass at 500-600° C. for 4-6 hours without oxygen, and then sieving to obtain a biochar material; (4) mixing the phosphate tailings material, the biochar material, and the agricultural waste material in a weight ratio of (1-5):(1-5):(1-5) to obtain a mixed material; (5) The mixed material is modified by microwave irradiation to obtain a composite soil conditioner.

2. The method for preparing a composite soil conditioner of phosphate tailings and biomass according to claim 1, characterized in that: In step (1), the product was sieved through an 80-mesh sieve.

3. The method for preparing a composite soil conditioner of phosphate tailings and biomass according to claim 1, characterized in that: The agricultural waste in step (2) is one or more of corn stalks and peanut shells.

4. The method for preparing a composite soil conditioner of phosphate tailings and biomass according to claim 1, characterized in that: In step (2), the mixture was sieved through a 20-mesh sieve.

5. The method for preparing a composite soil conditioner of phosphate tailings and biomass according to claim 1, characterized in that: The biomass in step (3) is one or more of corn stalks and peanut shells.

6. The method for preparing a composite soil conditioner of phosphate tailings and biomass according to claim 1, characterized in that: In step (3), the mixture was sieved through an 80-mesh sieve.

7. The method for preparing a composite soil conditioner of phosphate tailings and biomass according to claim 1, characterized in that: In step (5), the microwave power is 950 W and the irradiation time is 10 to 30 min.

8. A phosphate tailings and biomass composite soil conditioner prepared by the method according to any one of claims 1 to 6.