A method for preparing an acidic soil conditioner from mine waste stone powder, its product and application

Abstract

The present invention discloses a method for preparing an acidic soil conditioner from mine waste stone powder, as well as its product and application. The preparation method includes: S1: mixing the mine waste stone powder with an adhesive, granulating and post-treating to obtain stone powder particles; S2: placing waste shells and aquatic product leftovers in an acidic solution, standing for activation, washing to neutrality and then drying for standby; S3: performing high-temperature carbonization and expansion treatment on the product dried in step S2 in an anoxic or oxygen-free environment to obtain biochar; S4: uniformly mixing the stone powder particles prepared in step S1, the biochar prepared in step S3, waste shells, livestock manure, potassium humate and auxin to obtain an acidic soil conditioner. The preparation method disclosed by the present invention uses mine waste stone powder, waste shells and aquatic product leftovers as raw materials, which can not only effectively improve soil problems, solve the problem of waste of waste resources, turn waste into treasure, but also will not cause secondary harm to the soil environment.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and in particular to a method for preparing an acidic soil conditioner based on mine waste stone powder, its product, and its application in improving acidic soil. Background Art

[0002] Soil is the basis for plant growth, and the quality level of soil will directly affect the soil ecosystem and thus have an impact on the growth and development of plants. According to statistics, about 30% of the cultivated soil worldwide is acidic. Most of this type of acidic soil is distributed in the tropics, subtropics, and temperate zones. The area of acidified soil in China reaches 200 million hectares, accounting for about 23% of the total national area. The pH value of the soil has decreased by an average of 0.6 units in the past 30 years and shows a trend of continuing to worsen. The degradation of land quality caused by soil acidification has become a serious problem faced by the sustainable development of agriculture in China. Taking measures to prevent and control the acidification of cultivated soil according to local conditions and soil conditions will play a positive role in protecting the quality of cultivated land and improving the comprehensive production capacity of cultivated land.

[0003] A Chinese patent document with the application publication number CN 101935532 A discloses an acidic soil conditioner and its use. Specifically, the solid kelp residue generated during the production of sodium alginate is used as the raw material, which is dried and pulverized to obtain kelp residue powder as the acidic soil conditioner. The acidic soil conditioner prepared by this technical solution is in powder form, and after application, it may increase the soil bulk density to a certain extent and reduce the looseness of the soil. A Chinese patent document with the application publication number CN110872518A discloses an acidic soil conditioner, which uses Alcaligenes faecalis living bacteria as the functional bacteria. The total number of bacteria of Alcaligenes faecalis in every 1 milliliter of the acidic soil conditioner is greater than or equal to 5 billion. Through the life activities of the bacteria, the pH value of the acidic soil can be effectively increased, the EC value of the soil can be reduced, and the soil can release fixed nutrient elements. However, the components of this technical solution are relatively single, and it only improves the soil pH simply through the changes of microorganisms in the soil, but fails to solve the problems of nitrogen and phosphorus fixation and utilization in the soil, and cannot effectively solve the problems of lack of mineral nutrient ions such as K + , Ca 2+ , Mg 2+ etc. in the soil.

[0004] A Chinese patent document with the application publication number CN109097064A discloses an acidic soil conditioner, which is made from the following raw materials in parts by weight: 50 - 75 parts of dealuminized red mud powder, 15 - 30 parts of phosphogypsum, 5 - 10 parts of plant ash, 5 - 10 parts of calcium magnesium phosphate fertilizer, 0.5 - 1 part of compound microbial inoculum, and 10 - 25 parts of binder; the components in the acidic soil conditioner provided by this technical solution are relatively complex, and most of the raw materials are chemical components, which may cause secondary damage to the soil environment.

[0005] Dahuangshan Construction Stone Mine on Cezi Island, Zhoushan City, Zhejiang Province. The mine reserves are about 200 million tons. Since the construction stone is processed by wet method in the mine, the stone powder content is about 5%, the amount of stone powder is about 10 million tons, and the amount of stone powder produced annually is about 1 million tons. At present, most of the domestic mines of the same type with wet mining adopt the disposal method of transporting to other places for landfill, resulting in high disposal costs (at present, the treatment cost per ton is about 30 yuan, the annual disposal cost of stone powder is about 30 million yuan, and the total disposal cost is about 300 million yuan), and the problem of large environmental burden, which not only wastes resources, but also occupies land and causes environmental pollution. Due to the above reasons, it is very necessary to comprehensively utilize the waste stone powder in the mine.

[0006] However, the preparation of the acid soil conditioner disclosed in the prior art has the disadvantages of single composition, poor technological innovation, and inability to achieve the comprehensive treatment of the soil. It does not involve the actual production and processing scheme and application process technology, and there is no report on the application of tuff mine stone powder in acid soil improvement. Summary of the Invention

[0007] In view of the above problems existing in the prior art, the present invention discloses a preparation method of an acid soil conditioner, which uses waste stone powder in the mine, waste shells and aquatic product scraps as raw materials, can effectively improve soil problems, solve the problem of waste of waste resources, turn waste into treasure, and will not cause secondary harm to the soil environment.

[0008] The specific technical solution is as follows:

[0009] A method for preparing an acid soil conditioner based on waste stone powder in the mine, comprising the following steps:

[0010] S1: Mix the waste stone powder in the mine with an adhesive, and obtain stone powder particles through granulation and post-treatment;

[0011] S2: Place the waste shells and aquatic product scraps in an acidic solution, let them stand for activation, wash them to neutrality and then dry them for standby;

[0012] S3: Carbonize the product dried in step S2 at high temperature in an anoxic or oxygen-free environment to obtain a mixed carbon material, and then obtain biochar through expansion treatment;

[0013] S4: Mix the stone powder particles prepared in step S1, the biochar prepared in step S3, waste shells, livestock manure, potassium humate and auxin evenly to obtain the acid soil conditioner.

[0014] The present invention discloses a preparation method of an acid soil conditioner, which is prepared from waste stone powder of a mine, waste shells and aquatic product scraps as main raw materials by a specific process. The specific process includes two key points: First, the waste stone powder of the mine needs to be granulated. Through experiments, it is found that if it is not granulated (Comparative Example 1) and directly blended with other raw materials, the prepared soil conditioner has basically no improvement effect on acid soil, and the aeration degree is almost the same as that before treatment; if the granulation treatment is carried out at the last step (Comparative Example 7), from the pH value and aeration degree of the modified soil and the physical and chemical properties of the soil, it can be seen that the improvement effect of the prepared soil conditioner is extremely limited. Second, the waste shells used in the present invention are added in two ways. One is to blend and activate the waste shells with aquatic product scraps first and then add them after carbonization treatment, and the other is to add them directly; through experiments, it is found that if the waste shells are added only in one way, such as adding them after only simple pretreatment (Comparative Example 4) or all the waste shells are added after blending and activating with aquatic product scraps and then carbonization treatment (Comparative Example 5), the improvement effects of the prepared soil conditioner on the pH value and aeration degree of the soil are not good.

[0015] The waste stone powder of the mine used in the present invention is derived from the waste of wet processing of a tuff mine. The pH of the waste stone powder of the mine is alkaline by itself, and it contains rich potassium (K 2 O), calcium (CaO), magnesium (MgO), phosphorus (P 2 O 5 ), etc. Under the action of soil microorganisms, the waste stone powder of the mine can further ionize Mg 2+ , Ca 2+ and OH - . OH - can neutralize H + in the acid soil, and Mg 2+ and Ca 2+ can be absorbed and utilized by crops, which can significantly improve the acid soil environment, provide nutrients, and effectively balance the soil components.

[0016] Waste shells: As natural calcium-rich substances, they can effectively improve the acidity of acid soil, enhance the fertilizer-holding and fertilizer-supplying capacity and buffering capacity of the soil; selected from one or more of waste mussel shells, scallop shells, and Pinctada martensii shells.

[0017] Aquatic product scraps: Derived from the waste of aquatic product processing enterprises, selected from the processing wastes of one or more of shrimp shells, crab shells, fish bones, and large seaweeds. The large seaweeds are selected from common seaweeds such as kelp, purple laver, Sargassum, and Undaria pinnatifida.

[0018] The discarded shells and waste from aquatic product processing enterprises used above are easily obtainable in the Zhejiang region, and the production cost of the soil conditioner is low without additional costs.

[0019] Livestock manure: The useful nutrients in the manure can improve the content of nutrient elements in the soil, enhance the soil fertility, and increase the yield of crops.

[0020] Potassium humate: Potassium humate is a highly efficient organic potassium fertilizer. Since the humic acid in it is a biological active agent, it can increase the available potassium content in the soil, reduce the loss and fixation of potassium, increase the absorption and utilization rate of potassium by crops, and also has functions such as improving the soil, promoting crop growth, enhancing the stress resistance of crops, improving crop quality, and protecting the agricultural ecological environment.

[0021] Auxin: Plant auxin is a hormone produced by the cell region with division and enlargement activities that regulates the growth rate and direction of plants. Its chemical essence is indoleacetic acid. Its main function is to relax the plant cell wall, thereby enabling cell growth and elongation. In many plants, it can also increase the synthesis of RNA and proteins. It is a type of hormone that regulates plant growth, especially stimulates the longitudinal growth of cells in the stem and inhibits the transverse growth of cells in the root. It can affect the phototropism and gravitropism growth of the stem.

[0022] In step S1:

[0023] Preferably, the mass ratio of the waste stone powder from the mine to the binder is 100:1 to 10;

[0024] Further preferably, the mass ratio of the waste stone powder from the mine to the binder is 100:3 to 5. Through experiments, it is found that using the above further optimized addition amount of the binder has a better effect on improving the pH value of acidic soil and the effect on improving soil bulk density.

[0025] More preferably, the mass ratio of the waste stone powder from the mine to the binder is 100:5.

[0026] Preferably, the post-treatment includes crushing and sorting, and screening. The average particle size of the stone powder particles obtained through granulation and post-treatment is 1 to 8 mm; further preferably, the average particle size of the stone powder particles obtained through granulation and post-treatment is 4 mm.

[0027] In step S2:

[0028] Preferably, the acidic solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution, and the concentration is 0.1 to 2.0 M;

[0029] The time for static activation is 12 to 48 h.

[0030] Preferably:

[0031] The waste shells need to be pretreated, and the pretreatment includes washing and crushing;

[0032] The mass ratio of the waste shells to the aquatic product scraps is 1-2:5.

[0033] It has been found through experiments that if the aquatic product scraps are not added and compounded with the waste shells for carbonization treatment during the preparation of the mixed carbon material, the improvement effect of the prepared soil conditioner will be affected.

[0034] In step S3:

[0035] The anaerobic environment includes introducing an inert gas as the environmental atmosphere. The inert gas is selected from conventional types in the art, including nitrogen, helium, neon, and so on.

[0036] Preferably, for the high-temperature carbonization, the temperature is 600-800 °C and the time is 1-8 h.

[0037] It has been found through experiments that the carbonization temperature is the main controlling factor affecting the physical and chemical properties of biochar. If an inappropriate carbonization temperature is not selected, the prepared biochar will not have a rich pore structure and a large specific surface area, and ultimately its acidic soil improvement effect will be reduced.

[0038] More preferably, for the high-temperature carbonization, the temperature is 600-700 °C.

[0039] Preferably, the puffing treatment is carried out in a micro-nano puffing machine, and the treatment time is 2-10 h; it has been found through experiments that if the mixed carbon material is not subjected to puffing treatment, the acidic soil improvement effect of the prepared soil conditioner will be greatly affected. Preferably, in step S4, by weight, the composition of the raw materials includes:

[0040]

[0041] More preferably, based on a total weight of 100 parts, the composition of the raw materials includes:

[0042]

[0043] Preferably, the waste shells need to be pretreated, and the pretreatment includes washing and crushing.

[0044] The present invention also discloses an acidic soil conditioner prepared according to the above method.

[0045] The present invention also discloses the application of the above acidic soil conditioner in improving acidic soil. Specifically, before winter, the polluted soil is first plowed and the acidic soil conditioner is applied to effectively adjust the degree of soil acidification, achieving the effects of improving soil quality and increasing organic matter.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] In the preparation method of the present invention, the raw materials used, namely waste stone powder, waste shells, and aquatic product scraps, are all natural components. Using these raw materials to prepare the acidic soil conditioner can not only solve the problem of waste resource waste and turn waste into treasure, but also effectively improve soil problems without causing secondary harm to the soil environment.

[0048] The acidic soil conditioner prepared by the special process in the present invention not only effectively reduces the soil bulk density and soil hardness, improves the soil porosity, permeability, etc., thereby improving the soil structure; but also analyzes from aspects such as soil pH value, nitrogen, phosphorus, potassium and other soil physical and chemical properties, and pertinently improves the soil pH value, effectively increasing the content of available phosphorus, available potassium and organic matter in the soil, and improving the soil conductivity. Moreover, the raw materials of this acidic soil conditioner are widely sourced, safe, environmentally friendly, low-cost, and have a wide application range, with good economic and environmental benefits, and can be used on a large scale. Description of the Drawings

[0049] Figure 1 It is the scanning electron microscope photo of the waste mussel shells only after cleaning and crushing in Example 1;

[0050] Figure 2 It is the scanning electron microscope photo of the seaweed residue raw material used in Example 1 and the mixed carbon materials obtained after being treated at different carbonization temperatures;

[0051] Figure 3 It is the scanning electron microscope photo of the biochar prepared in Example 1;

[0052] Figure 4 It is the scanning electron microscope photo of the mine waste stone powder used in this example;

[0053] Figure 5 It is the influence curve of different acidic conditioners prepared in each example and comparative example on soil pH; Figure 6 It is the influence curve of different acidic conditioners prepared in each example and each comparative example on soil aeration. Detailed Description of the Invention

[0054] To make the purpose, technical solution and effects of the present invention clearer and more definite, the following further details the present invention in combination with examples and drawings. It should be understood, however, that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention. In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following examples, unless otherwise specified, are conventional methods in this field.

[0055] Example 1

[0056] S1: Mix 10 kg of mine waste stone powder with 500 g of ore powder pellet binder (α starch extract) dry, then evenly spray 1.5 L of water with a sprayer, form it through the dry roll pressing process technology of a granulator (DRG series double-roll dry extrusion granulator), and then obtain stone powder particles with an average particle size of 4 mm through the processes of crushing, sizing, and screening.

[0057] S3: Clean the surface of the waste mussel shells, gently remove the surface impurities with a knife, and then break them into small pieces.

[0058] S3: Place the pretreated mussel shells and seaweed residue in a 0.5 mol / L hydrochloric acid solution at a mass ratio of 1:5 for 24 h for activation treatment, wash with water until neutral, and dry.

[0059] S4: Place the dried material in step S3 in a muffle furnace in an oxygen-deficient state, heat up to 600 °C at a heating rate of 5 °C / min, hold for 3 hours, and then take it out after natural cooling to obtain the mixed carbon material.

[0060] S5: Place the mixed carbon material in a micro-nano puffing machine (HY-PH3010 graphite microwave puffing furnace) for puffing treatment for 6 h to obtain biochar, and dry it for standby.

[0061] S6: Mix 40 parts by weight of the stone powder particles prepared in step S1, 10 parts by weight of the biochar prepared in step S5, 10 parts by weight of waste mussel shells (only cleaned and broken), 15 parts by weight of livestock manure, 20 parts by weight of potassium humate, and 5 parts by weight of auxin evenly to obtain the acid soil conditioner A1.

[0062] Figure 1 This is the scanning electron microscope photo of the waste mussel shells only subjected to cleaning and crushing in this embodiment.

[0063] Figure 2 The scanning electron microscope photos of the seaweed residue raw material (Figure a) used in this embodiment and the mixed carbon materials obtained after carbonization treatment at different temperatures of 600 °C (Figure b), 700 °C (Figure c), 800 °C (Figure d), 900 °C (Figure e), and 1000 °C (Figure f) are given; it can be found by observing this figure that the mixed carbon materials after carbonization treatment have a good specific surface area and pore structure, which will be beneficial to increasing the active contact sites with the soil and is more conducive to improving the soil structure; however, when the temperature is too high, the pore structure collapses and the relative specific surface area decreases. It can be known from the BET test that the specific surface area of the seaweed residue raw material is 90.56 m 2 / g, the specific surface area of the mixed carbon material obtained after carbonization at 600 °C is 1738 m 2 / g, and the specific surface area of the mixed carbon material obtained after carbonization treatment at 700 °C is 1198 m 2 / g, the specific surface area of the mixed carbon material obtained after carbonization treatment at 800 °C is 531 m 2 / g, the specific surface area of the mixed carbon material obtained after carbonization treatment at 900 °C is 301.8 m 2 / g, the specific surface area of the mixed carbon material obtained after carbonization treatment at 1000 °C is 814.4 m 2 / g.

[0064] Figure 3 This is the scanning electron microscope photo of the biochar prepared after step S5 in this example.

[0065] The mine waste stone powder used in this example is grayish-black, muddy, with a water content of 25 - 35 wt%,

[0066] Figure 4 This is the scanning electron microscope photo of the mine waste stone powder used in this example. It can be observed that the morphology of this stone powder sample consists of particles of different sizes, and there are flaky structures on the particles. Through further particle size analysis, it can be known that the finest particles start to appear at 0.523 μm. The volume percentage between 0.523 - 1.125 μm (including 5 particle classification intervals) is 3.38%, the volume percentage between 1.125 - 4.034 μm (including 11 particle classification intervals) is 13.09%, the volume percentage between 4.034 - 11.201 μm (including 5 particle classification intervals) is 14.11%, the volume percentage between 11.201 - 31.100 μm (including 5 particle classification intervals) is 18.54%, the largest particle percentage appears between 31.100 - 126.652 μm (including 10 particle classification intervals) with a volume percentage of 25.89%, the volume percentage between 126.652 - 399.555 μm (including 8 particle classification intervals) is 22.89%, and the particle percentage greater than 399.555 μm does not appear, and the volume percentages of the subsequent particle classification intervals are all 0. Generally speaking, the volume percentage below 325 mesh (44 μm) is 61.12%. Through pH value testing, it can be known that the pH value of the mine waste stone powder used in this example is 9.06.

[0067] The composition of the mine waste stone powder used in this example was analyzed. Three samples were taken for statistics, and the specific composition results are shown in Table 1 below.

[0068] Table 1

[0069] Sample number <![CDATA[SiO 2 / %]]> CaO / % <![CDATA[K 2 O / %]]> <![CDATA[Sodium 2 O / %]]> <![CDATA[SO 3 / %]]> MgO / % A 63.63 2.98 3.52 2.56 0.04 0.32 B 63.68 3.01 3.52 2.49 0.042 0.34 C 63.50 3.09 3.55 2.51 0.042 0.39 Average 63.60 3.03 3.53 2.52 0.041 0.35

[0070] Example 2

[0071] S1: Dry mix 10 kg of mine waste stone powder with 100 g of ore powder pellet binder (α - starch extract), then evenly spray 1.5 L of water with a sprayer, and form it through the dry roll - pressing process technology of a granulator (DRG series double - roll dry extrusion granulator). Then, through the processes of crushing, sizing, and screening, obtain stone powder particles with an average particle size of 1 mm;

[0072] S2: Clean the surface of the waste fan shells, gently remove the surface impurities with a knife, and then break them into small pieces;

[0073] S3: Place the pretreated fan shells and shrimp shells in a 0.5 mol / L hydrochloric acid solution at a mass ratio of 1:1 for 24 h for activation treatment, wash with water until neutral, and dry;

[0074] S4: Place the dried material in a muffle furnace in an oxygen - deficient state, heat it to 700 °C at a heating rate of 10 °C / min, hold for 3 hours, and then take it out after natural cooling to obtain the mixed carbon material;

[0075] S5: Place the mixed carbon material in a micro - nano expander for 6 h of expansion treatment to obtain biochar, and dry it for standby;

[0076] S6: Mix 50 parts by weight of the stone powder particles prepared in step S1, 18 parts by weight of the biochar prepared in step S5, 5 parts by weight of waste fan shells (only cleaned and broken), 15 parts by weight of livestock manure, 5 parts by weight of potassium humate, and 7 parts by weight of auxin evenly to obtain the acidic soil conditioner A2.

[0077] Example 3

[0078] S1: Dry mix 10 kg of mine waste stone powder with 100 g of ore powder pellet binder (α - starch extract), then evenly spray 1.5 L of water with a sprayer, and form it through the dry roll - pressing process technology of a granulator (DRG series double - roll dry extrusion granulator). Then, through the processes of crushing, sizing, and screening, obtain stone powder particles with an average particle size of 4 mm;

[0079] S2: Clean the surface of the waste Pinctada martensii shell raw material, gently remove the surface impurities with a knife, and then break them into small pieces;

[0080] S3: Place the pretreated shells and fish bones in a 0.5 mol / L hydrochloric acid solution at a mass ratio of 1:5 for 12 h for activation treatment, wash with water until neutral, and dry;

[0081] S4: Place the dried material in a muffle furnace in an oxygen - deficient state, heat it to 700 °C at a heating rate of 10 °C / min, hold for 3 hours, and then take it out after natural cooling to obtain the mixed carbon material;

[0082] S5: Place the mixed carbon material in a micro-nano expander for 5 h of expansion treatment to obtain biochar, and dry it for standby;

[0083] S6: Mix 40 parts by weight of the stone powder particles prepared in step S1, 10 parts by weight of the biochar prepared in step S5, 10 parts by weight of waste Pinctada martensii shells (only cleaned and crushed), 15 parts by weight of livestock manure, 20 parts by weight of potassium humate, and 5 parts by weight of auxin evenly to obtain the acidic soil conditioner A3.

[0084] Example 4

[0085] S1: Dry-mix 10 kg of mine waste stone powder with 300 g of mineral powder pellet binder (α-starch extract), then evenly spray 1.5 L of water with a sprayer, and form it by the dry rolling process technology of a granulator (DRG series double-roll dry extrusion granulator), and then through the processes of crushing, sizing and screening to obtain stone powder particles with an average particle size of 4 mm;

[0086] S2: Clean the surface of the waste mussel shell raw material, gently remove the surface impurities with a knife, and then break it into small pieces;

[0087] S3: Place the pretreated mussel shell and seaweed residue in a 0.5 mol / L hydrochloric acid solution at a mass ratio of 2:5 for 12 h for activation treatment, wash with water until neutral, and dry;

[0088] S4: Place the dried material in a muffle furnace in an oxygen-deficient state, heat it to 700 °C at a heating rate of 10 °C / min, keep it warm for 3 hours, and then take it out after natural cooling to obtain the mixed carbon material;

[0089] S5: Place the mixed carbon material in a micro-nano expander for 5 h of expansion treatment to obtain biochar, and dry it for standby;

[0090] S6: Mix 40 parts by weight of the stone powder particles prepared in step S1, 15 parts by weight of the biochar prepared in step S5, 10 parts by weight of waste mussel shells (only cleaned and crushed), 15 parts by weight of livestock manure, 15 parts by weight of potassium humate, and 5 parts by weight of auxin evenly to obtain the acidic soil conditioner A4.

[0091] Example 5

[0092] The preparation process is basically the same as that of Example 1, except that in step S1, by adjusting the size of the roll skin during the dry rolling process, stone powder particles with an average particle size of 1 mm are prepared, and finally the acidic soil conditioner A5 can be obtained.

[0093] Example 6

[0094] The preparation process is basically the same as that of Example 1, except that in step S1, by adjusting the size of the roller skin during the dry roll pressing process, stone powder particles with an average particle size of 8 mm are prepared, and finally the acidic soil conditioner A6 can be obtained.

[0095] Example 7

[0096] The preparation process is basically the same as that of Example 1, except that in step S1, by adjusting the addition amount of the binder, stone powder particles with a binder addition amount of 1 wt% are prepared, and finally the acidic soil conditioner A7 can be obtained.

[0097] Comparative Example 1

[0098] The preparation process is basically the same as that of Example 1, except that the waste stone powder from the mine is not granulated, and 40 parts by weight of the waste stone powder from the mine is directly used to replace the same mass of stone powder particles with an average particle size of 4 mm. At this time, the acidic soil conditioner D1 is prepared.

[0099] Comparative Example 2

[0100] Steps S1 to S2 are exactly the same as those in Example 1;

[0101] S3: Place the pretreated mussel shells in a 0.5 mol / L hydrochloric acid solution for 24 h for activation treatment, wash with water until neutral, and dry;

[0102] S4: Place the dried material in a muffle furnace in an oxygen-deficient state, heat it to 600 °C at a heating rate of 5 °C / min, hold for 3 hours, and then take it out after natural cooling to obtain the carbon material;

[0103] S5: Place the carbon material in a micro-nano expander for 6 h of expansion treatment to obtain biochar, and dry it for standby;

[0104] S6: Mix 40 parts by weight of the stone powder particles prepared in step S1, 10 parts by weight of the biochar prepared in step S5, 10 parts by weight of waste mussel shells (only cleaned and crushed), 15 parts by weight of livestock manure, 20 parts by weight of potassium humate, and 5 parts by weight of auxin evenly to prepare the acidic soil conditioner D2.

[0105] Comparative Example 3

[0106] The preparation process is basically the same as that of Example 1, except that the mixed carbon material prepared in step S4 is not subjected to expansion treatment, and 10 parts by weight of the mixed carbon material is directly used to replace the same mass of biochar. At this time, the acidic soil conditioner D3 is prepared.

[0107] Comparative Example 4

[0108] Step S1 is the same as that in Example 1;

[0109] S2: Place 1 kg of seaweed residue in 0.5 mol / L hydrochloric acid solution for activation treatment for 24 h, wash with water until neutral, and dry.

[0110] S3: Place the dried material in a muffle furnace in an oxygen-deficient state, heat up to 600 °C at a heating rate of 5 °C / min, hold for 3 hours, and then take it out after natural cooling to obtain the carbon material.

[0111] S4: Mix 40 parts by weight of the stone powder particles prepared in step S1, 5 parts by weight of the carbon material prepared in step S3, 20 parts by weight of waste mussel shells (only cleaned and crushed), 15 parts by weight of livestock manure, 15 parts by weight of potassium humate, and 5 parts by weight of auxin evenly to prepare the acidic soil conditioner D4.

[0112] Comparative Example 5

[0113] The preparation process is basically the same as that of Example 1, except that in step S6, 40 parts by weight of the stone powder particles prepared in step S1, 20 parts by weight of the biochar prepared in step S5, 15 parts by weight of livestock manure, 20 parts by weight of potassium humate, and 5 parts by weight of auxin are mixed evenly to obtain the acidic soil conditioner D5.

[0114] Comparative Example 6

[0115] The preparation process is basically the same as that of Example 1, except that in step S4, the carbonization temperature for preparing the mixed carbon material is 1000 °C to obtain the acidic soil conditioner D6.

[0116] Comparative Example 7

[0117] S1: Clean the surface of the waste mussel shells, gently remove the surface impurities with a knife, and then break them into small pieces.

[0118] S2: Place the pretreated mussel shells and seaweed residue in 0.5 mol / L hydrochloric acid solution at a mass ratio of 1:5 for 24 h for activation treatment, wash with water until neutral, and dry.

[0119] S3: Place the dried material in step S3 in a muffle furnace in an oxygen-deficient state, heat up to 600 °C at a heating rate of 5 °C / min, hold for 3 hours, and then take it out after natural cooling to obtain the mixed carbon material.

[0120] S4: Place the mixed carbon material in a micro-nano puffing machine (HY-PH3010 graphite microwave puffing furnace) for puffing treatment for 6 h to obtain biochar, and dry it for standby.

[0121] S5: Mix 40 parts by weight of stone powder, 10 parts by weight of the biochar prepared in step S4, 10 parts by weight of waste mussel shells (only cleaned and crushed), 15 parts by weight of livestock manure, 20 parts by weight of potassium humate, and 5 parts by weight of auxin evenly.

[0122] S6: Mix 10 kg of the mixed sample with 500 g of mineral powder pellet binder (α - starch extract) dry - mix evenly, then spray 1.5 L of water evenly with a sprayer, and form it by the dry - roll pressing process technology of a granulator (DRG series double - roll dry extrusion granulator). Then, through the processes of crushing, sizing, and screening, obtain mixed sample particles with an average particle size of 4 mm, namely, the acidic soil conditioner D7.

[0123] Performance test: Acidic soil improvement experiment

[0124] The soil sample plot is a blank plot without crop planting, the pH value of the soil is 3.9 ± 0.3. After the collected soil sample is naturally air - dried, remove stones and other sundries, pass through a 2 - mm nylon sieve, and then put it into a self - sealing bag and store it at 4°C for standby.

[0125] Use potted plants to cultivate the blank soil, with 3 kg of soil in each pot. Set 3 replicates for the treatment, and evenly mix the soil with the acidic soil conditioner (mass ratio 50:1) and then put it into the pot. During the test period, replenish deionized water once every 2 - 4 days on average, and use the weighing method to keep the soil moisture content at 20%, ensuring that the soil surface is slightly moist. On the 25th day after the test treatment, use a cylindrical soil sampler with a length of 300 mm and a diameter of 15 mm to vertically insert into the soil to take samples, randomly take 5 samples from each pot, detect the pH value of the taken soil samples, and at the same time detect the basic chemical properties of the taken soil samples.

[0126] (1) Effects of different acidic soil conditioners on soil pH

[0127] The soil pH value is also known as soil acidity - alkalinity. Soil acidity - alkalinity is one of the important basic properties of soil and is an index in the process of soil formation, ripening, and fertilization. Each plant has its suitable pH range, and growth will be hindered if it exceeds this range. According to the soil zonality distribution law in China, it is more appropriate to divide the soil acidity - alkalinity into five - level attributes for practical application. The five - level acidity - alkalinity are: strongly acidic (pH < 5.0), acidic (pH 5.0 - 6.5), neutral (pH 6.5 - 7.5), alkaline (pH 7.5 - 8.5), strongly alkaline (pH > 8.5). In China, most of the soil plots are acidic and neutral soils.

[0128] Figure 5 gives the pH values of this acidic soil after adding different acidic soil conditioners, as well as the pH value of the control group (CK).

[0129] (2) Effects of different acidic soil conditioners on soil nutrients

[0130] The soil EC value refers to the soil electrical conductivity. The soil EC value is an index for measuring soil water-soluble salts, and soil water-soluble salts are an important index for the inorganic nutrients that can be rapidly utilized by plants in the surface soil and a factor for determining whether salt ions in the soil limit crop growth. The EC value is generally between 0.4 and 2. If the content of soluble salts (EC value) in the substrate is too high, it may form an osmotic pressure reverse, displace the water in the root system, and cause the root tip to turn brown or dry. The fluctuation of substrate humidity will further exacerbate the problem of too high soluble salt content, seriously damage the plant root system, and make it unable to absorb water and nutrients, resulting in symptoms such as plant wilting, yellowing, tissue necrosis, or plant dwarfism. Too high EC value will also increase the occurrence probability of root rot caused by Pythium aphanidermatum.

[0131] The content of total potassium in the soil can only indicate the abundance or deficiency of the total potassium storage in the soil and cannot indicate the potassium supply situation for the current-season crops. Generally, there is not a lack of total potassium in the soil, but the available potassium is only 20 - 200 mg / kg -1 K, far less than the total potassium content (the total potassium in the plow layer soil of the North China Plain is approximately 1.7 - 2.2% K, or 2.0 - 2.6% K). It is necessary to determine the application rate of potassium fertilizer, and the determination of soil available potassium is very meaningful. The abundance and deficiency standards for the content of soil available potassium (K) (mg / kg) are: <30 is extremely low; 30 - 60 is low; 60 - 100 is medium; 100 - 160 is high; >160 is extremely high. Table 2 below gives the basic chemical properties of acidic soil and soil after adding different acidic modifiers.

[0132] Table 2

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[0134]

[0135] It can be seen from Table 2 that after applying the modifier to the soil, the soil nutrients have changed among different treatments. Compared with the unmodified acidic soil, with the addition of the modifier, the soil conductivity can be improved. With the addition of the modifier, the content of available phosphorus in the soil also shows an increasing trend. Among them, the content of available phosphorus in the soil of treatment A1 increases to 28.7 ± 0.4, which is about 22 (mg·kg -1 ) higher than that of the blank group, and the values of each example have increased significantly, and the values of the comparative examples have also increased, but the differences among the treatments are not obvious. With the application of the modifier, the content of available potassium in the soil increases significantly. Among them, the content of available potassium in the soil of treatment A1 is about 180 mg / kg higher than that of the blank group -1 , showing a significant level. Compared with the blank group, the organic matter content shows an upward trend with the application of the modifier, and except for comparative example 7, the differences among the treatments are not obvious.

[0136] (3) Effects of Different Acidic Amendments on Soil Aeration

[0137] Soil aeration was measured by the core method: The soil samples were collected by the core method. In the standard plot, sampling points with relatively consistent environmental factors were selected in the soil layer by the S-shaped sampling method and marked for the determination of soil physical properties. The sampling was repeated three times.

[0138] Figure 6 The effects of different acidic amendments on soil aeration are given in Figure 6 It can be seen that compared with the blank group, the soil aeration of different amendment treatments showed an increasing trend to varying degrees, indicating that the differences in the application of amendments were sufficient to cause significant changes in soil aeration. With the application of amendments, the aeration could show an upward trend. Moreover, the stone powder maintained good granularity in the soil after granulation, and the added mussel shell skeleton material could maintain long-term stability, and the persistence of soil structure improvement was better.

[0139] In summary, Example 1 can play the best role in improving acidic soil. It can not only effectively increase the pH of acidic soil, but also play the role of the skeleton support of stone powder particles and mussel shells in the soil. As a good soil fluff structure, it can also effectively increase the contact area between the active ingredients and the soil and better complete the delivery of nutrient components.

Claims

1. A method for preparing an acidic soil conditioner based on mine waste stone powder, characterized in that, it comprises the following steps: S1: Mix the mine waste stone powder with an adhesive, and obtain stone powder particles through granulation and post-treatment; S2: Place the waste shells and fishery by-products in an acidic solution, let it stand for activation, wash until neutral, and then dry for standby; The mass ratio of the waste shells to the fishery by-products is 1-2:5; S3: Carbonize the product dried in step S2 at high temperature in an anoxic or oxygen-free environment to obtain a mixed carbon material, and then obtain biochar through expansion treatment; S4: Mix the stone powder particles prepared in step S1, the biochar prepared in step S3, waste shells, livestock manure, potassium humate and auxin evenly to obtain the acidic soil conditioner; By weight, the composition of the raw materials includes: 20-50 parts of stone powder particles; 5-20 parts of biochar; 5-20 parts of waste shells; 10-20 parts of livestock manure; 5-20 parts of potassium humate; 5-10 parts of auxin.

2. The method for preparing an acidic soil conditioner based on mine waste stone powder according to claim 1, characterized in that, in step S1: The mass ratio of the mine waste stone powder to the adhesive is 100:1-10; The post-treatment includes crushing and screening, and the average particle size of the stone powder particles obtained through granulation and post-treatment is 1-8 mm.

3. The method for preparing an acidic soil conditioner based on mine waste stone powder according to claim 1, characterized in that, in step S2: The waste shells are selected from one or more of waste mussel shells, scallop shells, and Pinctada martensii shells; The fishery by-products are selected from processing wastes of one or more of shrimp shells, crab shells, fish bones, and large seaweeds; The acidic solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution, and the concentration is 0.1-2.0 M; The time for standing activation is 12-48 h.

4. The method for preparing an acidic soil conditioner based on mine waste stone powder according to claim 3, characterized in that: The waste shells also need to be pretreated, and the pretreatment includes cleaning and crushing.

5. The method for preparing an acidic soil conditioner based on mine waste stone powder according to claim 1, characterized in that, in step S3: For the high-temperature carbonization, the temperature is 600-800 °C and the time is 1-8 h; The expansion treatment is carried out in a micro-nano expander, and the treatment time is 2-10 h.

6. The method for preparing an acidic soil conditioner based on mine waste stone powder according to claim 1, characterized in that, The waste shells also need to be pretreated, and the pretreatment includes washing and crushing.

7. The method for preparing an acidic soil conditioner based on mine waste stone powder according to any one of claims 1-6, characterized in that: in step S1: The mass ratio of the mine waste stone powder to the adhesive is 100:3-5; The post-treatment includes crushing and screening, and the average particle size of the stone powder particles obtained through granulation and post-treatment is 4-8 mm; in step S3: For the high-temperature carbonization, the temperature is 600-700 °C; In step S4, by weight, the composition of the raw materials includes: 40 - 50 parts of stone powder particles; 10 - 18 parts of biochar; 5 - 10 parts of waste shells; 10 - 20 parts of livestock manure; 5 - 20 parts of potassium humate; 5 - 10 parts of auxin.

8. An acidic soil conditioner prepared by the method according to any one of claims 1 - 7.

9. Use of the acidic soil conditioner according to claim 8 in improving acidic soil.

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