Sand washing tailing mud artificial planting soil and preparation method thereof

Abstract

The invention provides sand washing tailing mud artificial planting soil and a preparation method thereof, and relates to the technical field of waste resource utilization. The method comprises the following steps: mixing the sand washing tail mud, cement and water to obtain mixed slurry; the method comprises the following steps: physically foaming an aqueous solution of a soil structure restoring agent to form prefabricated foam, thereby obtaining a foamed soil structure restoring solution; mixing the foamed soil structure recovery liquid with the mixed slurry to obtain soil slurry; the soil slurry is cured, crushed and screened, and alkaline soil is obtained; adjusting the pH value of the alkaline soil to 7-8 to obtain slightly neutral soil; and mixing the partial neutral soil with organic matters to obtain the artificial planting soil. The sand washing tail mud is prepared into the planting soil for plant growth, resource utilization of the sand washing tail mud is achieved, and the environmental problem caused by laying and stacking of the sand washing tail mud is relieved.

Description

Technical Field

[0001] The invention relates to the technical field of waste resource utilization, and in particular to an artificial planting soil of sand washing tailings and a preparation method thereof. Background Art

[0002] Sand washing tailings are tailings waste generated in water-based ore dressing / sand or ore washing / sand operations. They are mainly composed of silicate and carbonate minerals with a particle size between 0.001 and 1 mm.

[0003] Most of the sand washing tailings are transported to the suburbs by construction units without any treatment and piled up in the open air or buried. This not only occupies a large amount of land resources, but also causes dust, powder, flying sand and other problems during transportation and stacking, causing serious environmental pollution. Summary of the invention

[0004] The purpose of the present invention is to provide an artificial planting soil of sand washing tailings and a preparation method thereof. The present invention prepares the sand washing tailings into planting soil that can be used for plant growth, realizes the resource utilization of the sand washing tailings, and alleviates the environmental problems caused by the shelving and accumulation of the sand washing tailings.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing artificial planting soil by using sand washing tailings, comprising the following steps:

[0007] Mixing sand washing tailings, cement and water to obtain a mixed slurry;

[0008] Physically foaming the soil structure restoration agent to form prefabricated foam to obtain a foamy soil structure restoration liquid;

[0009] Mixing the foamed soil structure restoration liquid with the mixed slurry to obtain soil slurry;

[0010] The soil slurry is cured, crushed, and screened to obtain alkaline soil;

[0011] The pH value of the alkaline soil is adjusted to 7-8 to obtain artificial planting soil.

[0012] Preferably, the water content of the sand washing tailings is 20-30wt%.

[0013] Preferably, the mass of the sand-washing tailings is calculated on a dry weight basis, and the mass of the sand-washing tailings accounts for 50-70% of the total mass of the sand-washing tailings and cement.

[0014] Preferably, the cement is PO42.5 cement.

[0015] Preferably, the mass ratio of water to solid dry matter in the mixed slurry is 0.5-0.65:1.

[0016] Preferably, the mass of the soil structure restoration agent is 4-8% of the mass of the solid dry matter in the mixed slurry.

[0017] Preferably, the reagent used to adjust the pH value of the alkaline soil to 7-8 is a phosphoric acid solution, and the mass fraction of the phosphoric acid solution is 0.1-1%.

[0018] Preferably, the curing is natural curing, and the time of the natural curing is 14 to 28 days.

[0019] Preferably, the amount of organic matter added is 15-20% of the dry weight of the neutral soil.

[0020] The present invention provides artificial planting soil obtained by the method described in the above scheme.

[0021] The invention provides a method for preparing artificial planting soil by using sand washing tailings, comprising the following steps: mixing sand washing tailings, cement and water to obtain a mixed slurry; physically foaming a soil structure restoration agent to form prefabricated foam to obtain a foamy soil structure restoration liquid; mixing the foamy soil structure restoration liquid with the mixed slurry to obtain soil slurry; curing, crushing and screening the soil slurry to obtain alkaline soil; adjusting the pH value of the alkaline soil to 7-8 to obtain neutral soil; and mixing the neutral soil with organic matter to obtain artificial planting soil.

[0022] The invention uses sand washing tailings and cement as raw materials, wherein cement can make the artificial soil form strong particles, and the water absorption, water retention and air permeability of the particles can be improved by foaming to make them more suitable for plant growth.

[0023] The whole preparation process of the invention is simple, and the sand washing tailings are prepared into planting soil that can be used for plant growth, thereby realizing the resource utilization of the sand washing tailings and alleviating the environmental problems caused by the shelving and accumulation of the sand washing tailings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the method for preparing artificial planting soil using sand washing tailings of the present invention;

[0025] Figure 2 The diagrams are the changes before and after the growth of plants in Examples 1 to 3, and each row from left to right is B1 (Example 2), B2 (Example 1) and B3 (Example 3). DETAILED DESCRIPTION

[0026] like Figure 1As shown, the present invention provides a method for preparing artificial planting soil using sand washing tailings, comprising the following steps:

[0027] Mixing sand washing tailings, cement and water to obtain a mixed slurry;

[0028] Physically foaming the soil structure restoration agent to form prefabricated foam to obtain a foamy soil structure restoration liquid;

[0029] Mixing the foamed soil structure restoration liquid with the mixed slurry to obtain soil slurry;

[0030] The soil slurry is cured, crushed, and screened to obtain alkaline soil;

[0031] Adjusting the pH value of the alkaline soil to 7-8 to obtain a neutral soil;

[0032] The neutral soil is mixed with organic matter to obtain artificial planting soil.

[0033] The invention mixes sand washing tailings, cement and water to obtain mixed slurry.

[0034] The present invention has no special requirements on the source of the sand washing tailings, and any source known in the art can be used. In the present invention, the water content of the sand washing tailings is preferably 20-30wt%, more preferably 22-28wt%, and further preferably 24-26wt%.

[0035] In the present invention, the sand washing tailings are preferably cleaned first and then mixed with cement.

[0036] In a specific experiment, for the convenience of laboratory preparation, the present invention preferably dries and grinds the cleaned sand washing tailings to obtain a raw material with a particle size of less than 1 mm.

[0037] When used in industrial mass production, the present invention does not require drying and grinding of sand washing tailings.

[0038] In the present invention, the cement is preferably PO42.5 cement. The use of PO42.5 cement in the present invention is conducive to ensuring the strength of the artificial planting soil.

[0039] In the present invention, the mass of the sand-washing tailings is based on dry weight, and the mass of the sand-washing tailings preferably accounts for 50-70% of the total mass of the sand-washing tailings and cement, more preferably 55-65%, and further preferably 58-62%.

[0040] In the present invention, the amount of water used is preferably such that the mass ratio of water to solid dry matter in the mixed slurry is 0.5-0.65:1, more preferably 0.55-0.60:1. In the present invention, the mass of the solid dry matter refers to the sum of the dry weight of the sand washing tailings and the mass of cement.

[0041] The present invention has no special requirements for the mixing process of the sand washing tailings, cement and water, and a mixing process known in the art can be used. In the embodiment of the present invention, the mixing is performed at a speed of 50 r / min counterclockwise and clockwise for 2 minutes respectively until the mixed slurry is uniform.

[0042] The present invention physically foams the soil structure restoration agent to form prefabricated foam to obtain foamy soil structure restoration liquid.

[0043] In the present invention, the soil structure restoration agent preferably comprises the following components in percentage by weight: 0.1-1 wt% surfactant, 0.1-1 wt% foam stabilizer, 0.05-1 wt% enhancer, and the balance water.

[0044] Based on the total weight of the soil structure restoration agent as 100%, the soil structure restoration agent provided by the present invention includes 0.1-1wt% of a surfactant; in a specific embodiment of the present invention, the content of the surfactant may be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt% or 0.7wt%. In the present invention, the surfactant preferably includes one or more of alkyl glycosides, saponins, fatty alcohol polyoxyethylene ethers, α-olefin sulfonates, fatty alcohol polyoxyethylene ether sulfates, fatty alcohol polyoxyethylene ether carboxylates, soapberry saponins, betulin, lupeol, γ-sitosterol, betaine, coconut oil amide acetate, palmitamidopropyl ethylenediamine and oenothermide, and more preferably alkyl glycosides. In the present invention, the functions of surfactants include: (1) surfactant molecular structure: surfactant molecules have two parts: hydrophilic (polar) and hydrophobic (non-polar). The hydrophilic part is usually composed of polar groups (such as carboxyl, sulfonic acid or amino groups), and the hydrophobic part is usually a long-chain hydrocarbon group; (2) reducing surface tension: when the surfactant is dissolved in water, its molecules will be arranged at the interface between water and air, with the hydrophilic end facing the water phase and the hydrophobic end facing the air phase. This arrangement can significantly reduce the surface tension of water, making it easier for water to form foam; (3) forming a monolayer: on the water surface, the surfactant molecules will form a monolayer of monolayers. This membrane structure can stabilize air bubbles and make them less likely to break; (4) formation of foam: when the aqueous solution is mechanically agitated or air is injected, the air will be wrapped in the surfactant molecule layer to form bubbles. Since the surfactant reduces the surface tension of water, these bubbles can exist relatively stably.

[0045] Taking the total weight of the soil structure restoration agent as 100%, the soil structure restoration agent provided by the present invention includes 0.1-1wt% of a foam stabilizer. In a specific embodiment of the present invention, the content of the foam stabilizer can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt% or 0.7wt%. In the present invention, the foam stabilizer preferably includes one or more of nano-kaolin, nano-bentonite, nano-silicon dioxide, nano-attapulgite and nano-montmorillonite, more preferably nano-silicon dioxide. In the present invention, the particle size of the foam stabilizer is preferably 40-100nm, more preferably 50-80nm. In the present invention, taking nano kaolin as an example, the effects of the foam stabilizer include: (1) particle size and distribution: nano kaolin and the like have extremely small particle size and large specific surface area, which allows them to be evenly distributed in the liquid, thereby increasing the viscosity of the liquid and reducing the rate of bubble rupture; (2) enhancing foam stability: nano kaolin particles and the like form a network structure on the bubble surface or in the foam. The presence of these particles can increase the mechanical strength of the foam and prevent the merging and rupture of the bubbles; (3) improving the rheology of the liquid: the addition of nano kaolin and the like can improve the rheological properties of the liquid, making the liquid more viscous, thereby making the foam more stable and reducing the foam rupture caused by the fluidity of the liquid; (4) adsorption: nano kaolin particles and the like can be adsorbed on the gas-liquid interface of the foam, thereby increasing the interfacial tension of the foam and further stabilizing the foam structure.

[0046] Taking the total weight of the soil structure restoration agent as 100%, the soil structure restoration agent provided by the present invention includes 0.05-1% of the reinforcing agent, preferably 0.05-0.8wt%. In a specific embodiment of the present invention, the content of the reinforcing agent can be 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt% or 0.7wt%. In the present invention, the reinforcing agent includes cellulose and / or cellulose derivatives. In the present invention, the cellulose derivative preferably includes methyl cellulose. In the present invention, the relative molecular weight of the cellulose is preferably 50000-300000, more preferably 100000-200000. In the present invention, the relative molecular weight of the methyl cellulose is preferably 50000-300000, more preferably 100000-200000. In the present invention, taking cellulose as an example, the effects of the enhancer include: (1) increasing the viscosity of the solution: cellulose is a high molecular polymer that can form a high viscosity solution in water. The high viscosity solution can slow down the flow rate of the liquid in the bubble film, thereby reducing the rupture and merging of the foam and improving the stability of the foam; (2) forming a network structure: cellulose molecular chains can form a three-dimensional network structure in the aqueous solution. This structure can effectively surround and support the bubbles, prevent the merging of bubbles and the discharge of liquid, thereby extending the life of the foam; (3) adsorption at the gas-liquid interface: cellulose molecules can be adsorbed on the gas-liquid interface of the bubbles to form a dense protective film. This layer of film can increase the elasticity and toughness of the bubble membrane and reduce the damage to the bubbles caused by external stress; (4) Prevent bubble merging: Cellulose can effectively prevent bubble merging by increasing the strength of the foam liquid membrane, that is, the membrane between the bubbles breaks and forms larger bubbles, thus maintaining the fineness and uniformity of the foam; (5) Improve the rheological properties of the foam: The presence of cellulose in the solution increases the yield stress and elastic modulus of the solution, which makes the foam show better elastic recovery under the action of external force, thereby resisting the collapse and deformation of the foam.

[0047] The present invention has no special requirements on the preparation method of the soil structure restoration agent, and the components can be directly mixed evenly.

[0048] In the present invention, the role of the soil structure restoring agent is to improve the soil structure so that it can retain water, be breathable, and reduce soil compressibility.

[0049] The present invention has no special requirements for the implementation process of the physical foaming, and the physical foaming process known in the art can be used. In the present invention, the physical foaming multiple is preferably 20 to 30 times; the physical foaming to a foam density is preferably 60 to 80 g / L, the foam 1 hour sedimentation distance is preferably 20 to 30 mm, and the 1 hour water bleeding rate is 30 to 50%.

[0050] After obtaining the mixed slurry and the foamy soil structure recovery liquid, the present invention mixes the foamy soil structure recovery liquid with the mixed slurry to obtain soil slurry.

[0051] In the present invention, the mass of the soil structure restoration agent in the foamed soil structure restoration liquid is preferably 4-8% of the mass of the solid dry matter in the mixed slurry, more preferably 5-7%, and further preferably 6%.

[0052] In the present invention, the mixing is preferably carried out under stirring conditions, and the stirring speed is preferably 20 r / min; the present invention has no special requirements on the stirring time, as long as uniform stirring can be ensured.

[0053] After obtaining the soil slurry, the present invention performs curing, crushing and screening on the soil slurry to obtain alkaline soil.

[0054] In the present invention, the curing is preferably natural curing; the time of the natural curing is preferably 14 to 28 days. In the present invention, it is preferred to first perform natural curing in the mold for 1 to 2 days, and then remove the mold to continue natural curing. In the present invention, the function of the curing is to accelerate the hardening of the soil to make it reach the designed strength.

[0055] In the present invention, the crushing is preferably performed to a degree that the mass proportion of particles with a particle size of 0.05 to 4 mm in the alkaline soil exceeds 60%, more preferably the mass proportion of particles with a particle size of 0.05 to 0.1 mm in the alkaline soil is 10 to 15%, the mass proportion of particles with a particle size of 0.1 to 2 mm is 55 to 65%, and the mass proportion of particles with a particle size of 2 to 4 mm is 35 to 20%. The present invention obtains soil with a particle size distribution that meets the requirements of the specification through crushing.

[0056] Alkaline soil is obtained. The present invention adjusts the pH value of the alkaline soil to 7-8 to obtain neutral soil.

[0057] In the present invention, the reagent used to adjust the pH value of the alkaline soil to 7-8 is preferably a phosphoric acid solution, and the mass fraction of the phosphoric acid solution is preferably 0.1-1%, more preferably 0.3-0.8%, and further preferably 0.5-0.6%. The present invention preferably pours the phosphoric acid solution into the alkaline soil particles and stirs them, and measures the pH value of the soaking solution at regular intervals (preferably 4 hours) until the target pH is reached. After adjusting the pH value, the present invention preferably dries the obtained soil to obtain a neutral soil. In the present invention, the moisture content of the neutral soil is 20-30%.

[0058] In the present invention, the tailings of sand washing are alkaline, which leads to alkaline soil. The present invention adjusts the pH value of the soil to achieve the purpose of satisfying plant growth.

[0059] After obtaining the neutral soil, the present invention preferably mixes the neutral soil with organic matter to obtain artificial planting soil.

[0060] In the present invention, the organic matter can provide the nutrients required for plant growth. The present invention has no special requirements for the specific type of the organic matter, and any organic matter familiar to those skilled in the art can be used. For example, it can be animal fermented fertilizer or plant humus, and those skilled in the art can add it according to the growth habits of plants. In the present invention, the addition amount of the organic matter is preferably 15-20% of the dry weight of the neutral soil.

[0061] The present invention provides artificial planting soil obtained by the method described in the above scheme.

[0062] In the present invention, the artificial planting soil has good water absorption, water retention and air permeability, and has high strength, and is suitable for plant growth.

[0063] In the present invention, the content of organic matter in the artificial planting soil is preferably 15-20wt%; the water absorption rate of the artificial planting soil is preferably 70-80%; the 7d water holding rate is preferably 55-65%; the 28-day strength is preferably 5.3-6.5MPa; the density is preferably 1100-1200kg / m 3 .

[0064] The artificial planting soil of sand-washing tailing mud and the preparation method thereof provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0065] The preparation process of the soil structure restoration agent used in the following examples is as follows:

[0066] The saponin solution is prepared by dissolving saponin in water and stirring it with a glass rod until it is dissolved, and the saponin solution with a concentration of 1.25wt‰ (solution 1); nano-kaolin is dispersed in solution 1 and stirred with a glass rod until it is evenly dispersed, and the mass ratio of the nano-kaolin to the saponin is 1:1 (solution 2); methyl cellulose is added to solution 2, wherein the amount of methyl cellulose is 80wt% of the nano-kaolin, and the solution is stirred with a glass rod until it is evenly dispersed, and the stirring speed is 20r / min, to obtain a soil structure restoration agent.

[0067] Example 1

[0068] An artificial planting soil is prepared from the following materials: 330kg of PO42.5 cement, 770kg of dry weight of sand washing tailings, 25% of moisture content, 605kg of water (including the water content in the sand washing tailings), and 66kg of soil structure restoration agent.

[0069] The preparation process is as follows:

[0070] (1) Weigh the required amount of water and add it into a blender.

[0071] (2) Weighing and cleaning the sand washing tailings, drying and grinding them to obtain a sand washing tailings raw material with a particle size of less than 1 mm; pouring the sand washing tailings raw material and cement into a mixer, stirring at a speed of 50 r / min, clockwise and counterclockwise for 2 min respectively, until the slurry is uniform, to obtain a mixed slurry.

[0072] (3) Reduce the mixer speed to 20 r / min, use a foaming machine to foam the soil structure restoration agent (the mass of the soil structure restoration agent is 6% of the mass of the solid dry material in the mixed slurry), and then inject it into the mixer and stir it clockwise and counterclockwise for 1 to 2 minutes.

[0073] (4) Pour the mixed slurry into the required mold, cure for 1 day, remove the mold, and continue standard curing for 27 days. Its 28d strength is 5.3-6.5MPa, and its density is 1100-1200kg / m 3 (The prepared slurry has the phenomenon that the upper layer is lighter and the lower layer is heavier. Each mold material has certain differences, so the obtained strength and density are range values).

[0074] (5) The hardened soil is crushed, and the amount of soil particles with a size of 0.05-0.1 mm in the soil accounts for 10% of the total, the amount of soil particles with a size of 0.1-2 mm in the soil accounts for 55% of the total, and the amount of soil particles with a size of 2-4 mm in the soil accounts for 35% of the total. The pH value of the crushed soil particles is adjusted to 7-8 with 1% by mass phosphoric acid, and then dried to obtain a neutral soil.

[0075] (6) Mixing the neutral soil with organic matter, wherein the amount of the organic matter is 15% of the mass of the neutral soil, to obtain artificial planting soil. The prepared artificial planting soil has a water absorption rate of 75.2% and a 7-day water holding rate of 57.6%.

[0076] The artificial soil prepared in Example 1 was used to plant Elymus dahliae. Figure 2 As shown in (B2), the germination rate was 93%, the growth height was 18.5 cm in 20 days, the root length was 3-4 cm, the chlorophyll content was 0.6-0.8 mg / g, and the Na content in the plant roots was + Ion content is 4-8 mg / g, K + The ion content is 0.3-0.6 mg / g.

[0077] Example 2

[0078] An artificial planting soil is prepared from the following materials: 330 kg of cement, 770 kg of dry weight of sand washing tailings, 25% of moisture content, 605 kg of water (including the water content in the sand washing tailings), and 44 kg of soil structure restoration agent.

[0079] The preparation process is the same as that of Example 1, and the mass of the soil structure restoration agent is 4% of the mass of the solid dry material in the mixed slurry. The hardened soil before crushing has a 28d strength of 6.2-7.4 MPa and a density of 1220-1340 kg / m 3 The water absorption rate of the prepared artificial planting soil was 70.2%, and the 7d water holding rate was 55.1%.

[0080] The artificial soil prepared in Example 2 was used for growing Elymus salsa, such as Figure 2 As shown in (B1), the germination rate was 88%, the growth height was 17.5 cm in 20 days, the root length was 1-3 cm, the chlorophyll content was 0.4-0.6 mg / g, and the Na content in the plant roots was + Ion content is 2.4~6mg / g, K + The ion content is 0.2-0.4 mg / g.

[0081] Example 3

[0082] An artificial planting soil is prepared from the following materials: 330 kg of cement, 770 kg of dry weight of sand washing tailings, 25% of moisture content, 605 kg of water (including the water content in the sand washing tailings), and 88 kg of soil structure restoration agent.

[0083] The preparation process is the same as that of Example 1, and the mass of the soil structure restoration agent is 8% of the mass of the solid dry material in the mixed slurry. The hardened soil before crushing has a 28d strength of 3.9-4.6MPa and a density of 970-1080kg / m 3 The water absorption rate of the prepared artificial planting soil was 78.3%, and the 7d water holding rate was 54.1%.

[0084] The artificial soil prepared in Example 3 was used to plant Elymus dahliae. Figure 2 As shown in (B3), the germination rate was 90%, the growth height was 18 cm in 20 days, the root length was 2 to 3 cm, the chlorophyll content was 0.4 to 0.7 mg / g, and the Na content in the plant roots was + The ion content is 3-6 mg / g, K + The ion content is 0.3-0.4 mg / g.

[0085] From the above examples, it can be seen that the artificial planting soil prepared by using sand washing tailings as raw materials has water absorption, water retention, air permeability, and is suitable for plant growth. From the results of germination rate, growth height, root length, chlorophyll content, Na and K ion content, when the mass of soil structure restorer is 6% of the mass of solid dry matter in the mixed slurry, the obtained artificial planting soil is more suitable for plant growth.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing artificial planting soil using sand washing tailings, comprising the following steps: Mixing sand washing tailings, cement and water to obtain a mixed slurry; Physically foaming the soil structure restoration agent to form prefabricated foam to obtain a foamy soil structure restoration liquid; Mixing the foamed soil structure restoration liquid with the mixed slurry to obtain soil slurry; The soil slurry is cured, crushed, and screened to obtain alkaline soil; Adjusting the pH value of the alkaline soil to 7-8 to obtain a neutral soil; The neutral soil is mixed with organic matter to obtain artificial planting soil.

2. The method according to claim 1, characterized in that The water content of the sand washing tailings is 20-30wt%.

3. The method according to claim 1 or 2, characterized in that: The mass of the sand-washing tailings is calculated on a dry basis, and the mass of the sand-washing tailings accounts for 50-70% of the total mass of the sand-washing tailings and cement.

4. The method according to claim 1, characterized in that: The cement is PO42.5 cement.

5. The method according to any one of claims 1 to 4, characterized in that: The mass ratio of water to solid dry matter in the mixed slurry is 0.5-0.65:

1.

6. The method according to claim 1, characterized in that The mass of the soil structure restoration agent is 4-8% of the mass of the solid dry material in the mixed slurry.

7. The method according to claim 1, characterized in that The reagent used to adjust the pH value of the alkaline soil to 7-8 is a phosphoric acid solution, and the mass fraction of the phosphoric acid solution is 0.1-1%.

8. The method according to claim 1, characterized in that The curing is natural curing, and the time of the natural curing is 14 to 28 days.

9. The method according to claim 1, characterized in that: The amount of organic matter added is 15-20% of the dry weight of the neutral soil.

10. The artificial planting soil obtained by the method according to any one of claims 1 to 9.

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