High-consumption artificial nutrient soil based on geopolymer modified gold tailing mud and preparation method of high-consumption artificial nutrient soil

Abstract

The invention discloses high-consumption artificial nutrient soil based on geopolymer modified gold tailing mud and a preparation method of the high-consumption artificial nutrient soil, relates to the technical field of waste resource utilization and ecological restoration, and aims to solve the problems that the gold tailing mud occupies land due to accumulation, the environment is polluted by heavy metal, and the resource utilization rate is extremely low. Gold tailing mud is used as a core raw material, a geopolymer gelling system is matched to construct a stable framework and solidify heavy metal, organic nutrient components and a function regulator are compounded to optimize physicochemical properties and nutrient supply, and the artificial nutrient soil is prepared through the processes of raw material pretreatment, synergistic excitation, gradient maintenance and the like. According to the nutrient soil, super-large-scale absorption of gold tailing mud is achieved, meanwhile, the nutrient soil has a pore structure suitable for plant growth and water and fertilizer retention capacity, the heavy metal leaching amount meets the Soil Environment Quality Agricultural Land Soil Pollution Risk Management and Control Standard, and the plant growth requirements of landscaping, mine regreening, side slope ecological protection and other scenes can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste resource utilization and ecological restoration, more specifically, to a high-consumption artificial nutrient soil based on geopolymer modified gold tailings and a preparation method thereof. BACKGROUND

[0002] Gold tailings / tailing are the main solid waste generated in the process of gold mining and beneficiation, with annual emissions exceeding 50 million tons in China, and the cumulative accumulation amount has reached hundreds of millions of tons. This kind of solid waste not only occupies a large amount of land resources, but also contains lead, cadmium, mercury, arsenic and other heavy metals which can pollute the surrounding soil, water and air through leaching, weathering and other processes, causing serious ecological and environmental problems. At the same time, the tailings / tailing particles are small and loose in structure, and prone to landslides, mudslides and other geological disasters, which has become a key bottleneck restricting the green development of gold mining industry.

[0003] At present, the resource utilization of gold tailings / tailing is extremely limited, mainly concentrated in the fields of low-value road base filler and brick-making raw materials, with a utilization rate of less than 20%, and the risk of heavy metal pollution has not been solved. In the existing technology of preparing nutrient soil from solid waste, the proportion of solid waste is generally less than 60%, which cannot realize large-scale consumption of gold tailings / tailing, and there are problems such as poor heavy metal stabilization effect, insufficient structure stability of nutrient soil, weak water and fertilizer retention capacity, etc., which cannot meet the plant growth demand of ecological restoration scene.

[0004] Geopolymer, as a new type of inorganic cementing material, is formed by alkali activation reaction of aluminosilicate raw materials to form a three-dimensional network structure. It not only has the characteristics of high strength and high stability, but also can solidify heavy metals through physical wrapping and chemical adsorption, and can produce good interfacial bonding and synergistic reaction with the silicate and aluminate components in gold tailings / tailing. Based on this, the present application innovatively uses 80-90 parts by weight of gold tailings / tailing as the core raw material, combines with geopolymer technology to realize heavy metal stabilization and large-scale consumption of solid waste, and optimizes the nutrient components and preparation process to prepare an ecologically safe and excellent performance artificial nutrient soil, providing a new technical path for the resource utilization and ecological restoration of gold tailings / tailing. SUMMARY

[0005] In view of the technical problems of existing gold tailings / tailing pollution and low utilization rate, and the low consumption of existing solid waste nutrient soil and high risk of heavy metals, one of the purposes of the present application is to provide a high-consumption artificial nutrient soil based on geopolymer modified gold tailings, to realize large-scale consumption and harmless disposal of gold tailings / tailing, and at the same time obtain high-quality artificial nutrient soil suitable for ecological restoration scene.

[0006] To solve the above technical problems, the present application provides the following technical scheme: The application discloses a kind of high consumption capacity artificial nutrient soil based on geopolymer modified gold tailings sludge, including the following weight parts of raw materials: gold tailings sludge (gold mining / mining byproduct) 80-90 parts, geopolymer cementing system 5-12 parts, organic nutrient component 3-8 parts, functional regulator 1-4 parts, water 3-6 parts;Wherein, the geopolymer cementing system is compounded by alkali activator and aluminosilicate precursor according to mass ratio 1:3-1:5.

[0007] Preferably, the particle size of the gold tailings sludge is 120-200 mesh, wherein the SiO2 content is ≥50%, the Al2O3 content is ≥10%, the moisture content is ≤5%, and the pH value is 6.5-8.5, and the leaching amount of heavy metals (lead, cadmium, mercury, arsenic, etc.) after pretreatment meets the GB15618-2018 standard.

[0008] Preferably, the alkali activator is a mixed system of sodium hydroxide and water glass, and the mass ratio of sodium hydroxide to water glass is 1:4-1:6, and the modulus of water glass is 2.0-2.8.

[0009] Preferably, the aluminosilicate precursor is a mixture of one or more of fly ash, slag and metakaolin, and the active SiO2+Al2O3 content in the aluminosilicate precursor is ≥75%.

[0010] Preferably, the organic nutrient component is a mixture of one or more of decomposed straw, humus soil and biochar, and the organic matter content of the organic nutrient component is ≥45%, and the particle size is ≤3 mm.

[0011] Preferably, the functional regulator is a mixture of water-retaining agent, slow-release fertilizer, humic acid, heavy metal stabilizer and pH regulator according to mass ratio 1:1:1:1-2:1:1:1; the water-retaining agent is a polyacrylamide water-retaining agent; the slow-release fertilizer is a urea-formaldehyde resin coated compound fertilizer; the heavy metal stabilizer is humic acid or phosphorite powder; and the pH regulator is wood ash or potassium dihydrogen phosphate.

[0012] The core innovation of the application is to break through the limitation of the consumption capacity of traditional solid waste nutrient soil, take 80-90 parts of gold tailings / sludge as the core raw material, use the dual role of geopolymer cementing system: one is to build a stable skeleton of nutrient soil through three-dimensional network structure and optimize the pore structure; the other is to solidify heavy metals through physical wrapping, chemical adsorption and chemical bonding, and reduce environmental risk; combined with the nutrient supply function of organic nutrient component and the performance optimization of functional regulator, through scientific proportioning and process control, an artificial nutrient soil with ultra-large scale consumption, heavy metal stabilization and plant growth adaptability is prepared.

[0013] The gold tailing sludge is used as a core raw material, which is rich in SiO2 and Al2O3, can have a synergistic alkali activation reaction with a geopolymer cementitious system, can ensure the structural stability of the nutrient soil, and can maximize the solid waste consumption (80-90 parts); the geopolymer cementitious system selects an industrial solid waste precursor, further improves the comprehensive utilization efficiency of the solid waste, and realizes "waste treatment with waste". The organic nutrient component provides organic matter, nitrogen, phosphorus, potassium and other nutrients required for plant growth, the functional regulator is used for targeted optimization of water retention, fertilizer slow release and pH value, and the heavy metal stabilization effect is strengthened, so that the ecological safety and scene adaptability of the nutrient soil are ensured.

[0014] The second purpose of the present application is to provide a preparation method of a high-consumption artificial nutrient soil based on a geopolymer modified gold tailing sludge, which comprises the following steps: (1) The raw material is treated by a combined process of "magnetic separation and impurity removal + chemical stabilization": first, the ferromagnetic impurities are removed by magnetic separation, then 1-3% of a heavy metal stabilizer (humic acid or phosphorite powder) of the mass of the gold tailing sludge is added, the mixture is stirred uniformly, and then is left to stand for 24-48 h to reduce the activity of heavy metals; the organic nutrient component is crushed to a particle size of ≤3 mm for standby; (2) Geopolymer cementitious system preparation: mix the alkali activator and the aluminosilicate precursor in proportion, stir uniformly, and then leave to stand for 15-30 min for activation, and standby; (3) Mixing and stirring: first, the pretreated gold tailing sludge and the organic nutrient component are added to a stirrer, and dry mixing is performed for 8-15 min until they are uniformly mixed; then the geopolymer cementitious system and water are added, and wet mixing is performed for 20-30 min until the material is loose and has no clumps, and the stirring speed is controlled at 350-500 r / min; (4) Activation and curing: the mixed material is laid flat on the curing site, the environmental temperature is controlled at 22-32℃, the humidity is controlled at 65-85%, and the material is cured for 5-10 d; the material is sealed for curing for the first 3 d, is turned over once a day for the next 7 d, and is gradually ventilated and dehumidified to ensure uniform curing and stable structure; (5) Product processing: after curing, the material is crushed, sieved through an 8-10 mesh sieve, and the impurities are removed to obtain the artificial nutrient soil product.

[0015] Further, in the chemical stabilization process in step (1), the phosphorite powder is preferentially selected when the content of lead and cadmium is high, and the humic acid is preferentially selected when the content of arsenic and mercury is high.

[0016] Further, in the wet mixing process in step (3), 0.5-1 parts by weight of a biological agent can be added to improve the nutrient conversion efficiency of the nutrient soil, wherein the biological agent is a complex system of Bacillus subtilis and phosphorus solubilizing bacteria.

[0017] Further, the natural drying and ventilation can be combined in the step (4) in the later curing period of 7-10 days, so that the moisture content of the finished product is controlled at 15-20%, facilitating storage and transportation.

[0018] In the preparation process, the combined pretreatment process of "magnetic separation + chemical stabilization" effectively removes impurities and reduces the activity of heavy metals; the activation step of geopolymer ensures sufficient alkali activation reaction; and the mixed stirring and gradient curing process controls the structural stability and performance consistency of the nutrient soil, the overall process is simple and easy to operate, and is suitable for large-scale production.

[0019] Compared with the prior art, the beneficial effects of the present application are: 1. High solid waste disposal capacity: the ratio of gold tailings / tail mud is 80-90 parts by weight, the single batch disposal capacity is much higher than that of the prior art, and the stock of gold tailings / tail mud can be quickly digested, solving the problem of pollution caused by accumulation of mining solid waste; the geopolymer cementing system selects industrial solid waste precursors, and the comprehensive utilization rate of solid waste is more than 90%.

[0020] 2. Significant heavy metal stabilization effect: the three-dimensional network structure of geopolymer and the synergistic effect of functional regulators, the heavy metal leaching amount meets the GB 15618-2018 standard, there is no secondary pollution risk, and the ecological safety is high.

[0021] 3. Strong adaptability of physical and chemical properties: the pore structure formed by the cooperation of geopolymer and tailings / tail mud has a porosity of 30-45% and a water retention rate of ≥60%, and the pH value is stable in the suitable range of 6.0-7.5, which can meet the growth needs of ecological restoration pioneer plants such as alfalfa, sea buckthorn, and rye grass, and green plants.

[0022] 4. Low cost and wide application: the raw material is mainly gold tailings / tail mud, which is easy to obtain and low in price, and the preparation process is simple, so that the cost is only 40-60% of that of traditional ecological restoration soil after large-scale production; it can be widely used in mine greening, slope ecological protection, landscaping, saline-alkali land improvement and other scenes, and has environmental, economic and social benefits. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0024] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available. For any specific techniques or conditions not specified in the examples, they can be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Example

[0025] This embodiment provides a high-capacity artificial nutrient soil based on geopolymer-modified gold tailings.

[0026] 1. Raw material ratio (parts by weight): 80 parts gold tailings (150 mesh, 55% SiO2 content, 12% Al2O3 content, 4% moisture content, pH 7.3), 12 parts geopolymer cementing system (alkali activator: sodium hydroxide + water glass = 1:5, modulus 2.2; precursor: fly ash + slag = 1:1, active SiO2 + Al2O3 content 78%), 6 parts organic nutrient components (composted straw + biochar = 1:1, organic matter content 48%), 2 parts functional regulator (water-retaining agent + slow-release fertilizer + phosphate rock powder + wood ash = 1:1:1:1), 4 parts water; 2. Preparation steps: (1) The gold tailings were dried to a moisture content of 4%, crushed and passed through a 150-mesh sieve, and after magnetic separation to remove iron, 1.5% phosphate rock powder was added, stirred evenly and left to stand for 36 hours; the decomposed straw and biochar were crushed to a particle size ≤2mm. (2) Mix the alkaline activator and precursor, and activate for 20 min; (3) Dry mix the tailings and organic nutrients for 10 min, add the geological polymer gelling system, water and 0.8 parts of biological agent, and wet mix at 400 r / min for 25 min; (4) Curing at 28℃ and 75% humidity for 7 days, with the first 3 days sealed and the last 4 days turned over and ventilated once a day; (5) Grind the powder through a 10-mesh sieve to obtain the finished product.

[0027] 3. Performance testing: The artificial ecological nutrient soil prepared in this embodiment has a porosity of 38%, a water retention rate of 65%, a pH value of 6.9, an organic matter content of 7.2%, and the leaching amount of heavy metals (lead, cadmium, arsenic) is lower than the detection limit. The germination rate of alfalfa is 95%, and the root length is 25% longer than that of ordinary greening soil. Example

[0028] This embodiment provides a high-capacity artificial nutrient soil based on geopolymer-modified gold tailings.

[0029] 1. Raw material ratio (parts by weight): 85 parts of gold tailings (180 mesh, SiO2 content 52%, Al2O3 content 14%, moisture content 3%, pH value 7.8), 8 parts of geopolymer cementing system (alkali activator: sodium hydroxide + water glass = 1:6, modulus 2.5; precursor: metakaolin + fly ash = 1:2, active SiO2 + Al2O3 content 82%), 5 parts of organic nutrient components (humus + decomposed livestock and poultry manure = 2:1, organic matter content 46%), 3 parts of functional regulator (water retention agent + slow-release fertilizer + humic acid + potassium dihydrogen phosphate = 2:1:1:1), 5 parts of water; 2. Preparation steps: Same as in Example 1, except that 2% humic acid is added during pretreatment and the curing time is 8 days; 3. Performance testing: The artificial ecological nutrient soil prepared in this embodiment has a porosity of 42%, a water retention rate of 70%, a pH value of 7.2, an organic matter content of 6.8%, and a heavy metal leaching rate that meets the standards. When used for planting sea buckthorn in mine revegetation, the survival rate is 93%, and the growth cycle is shortened by 10 days compared with ordinary revegetation soil. Example

[0030] This embodiment provides a high-capacity artificial nutrient soil based on geopolymer-modified gold tailings.

[0031] 1. Raw material ratio (parts by weight): 90 parts of gold tailings + tailings mixture (200 mesh, SiO2 content 58%, Al2O3 content 11%, moisture content 5%, pH value 8.0), 5 parts of geopolymer cementing system (alkali activator: sodium hydroxide + water glass = 1:4, modulus 2.8; precursor: slag + metakaolin = 3:1, active SiO2 + Al2O3 content 76%), 3 parts of organic nutrient components (biochar + decomposed straw = 1:1, organic matter content 45%), 4 parts of functional regulator (water retention agent + slow-release fertilizer + phosphate rock powder + wood ash = 2:1:1:1), 6 parts of water; 2. Preparation steps: Same as in Example 1, except that 3% phosphate rock powder is added during pretreatment and the curing time is 10 days; 3. Performance testing: The artificial ecological nutrient soil prepared in this embodiment has a porosity of 35%, a water retention rate of 62%, a pH value of 7.4, an organic matter content of 5.9%, and meets the heavy metal leaching standards. When used for slope protection and planting ryegrass, the coverage rate is 90%, and the erosion resistance is improved by 30% compared with ordinary soil.

[0032] The core innovation of this invention lies in breaking through the limitations of traditional solid waste nutrient soil in terms of disposal capacity. Using 80-90 parts by weight of gold tailings / sludge as the core raw material, it utilizes the dual functions of a geological polymer cementing system: firstly, it constructs a stable framework for the nutrient soil through a three-dimensional network structure, optimizing the pore structure; secondly, it solidifies heavy metals through physical encapsulation, chemical adsorption, and chemical bonding, reducing environmental risks. Combined with the nutrient supply function of organic nutrient components and the performance optimization effect of functional regulators, through scientific formulation and process control, an artificial nutrient soil is prepared that combines ultra-large-scale disposal, heavy metal stabilization, and plant growth adaptability.

[0033] During the preparation process, a combined pretreatment process of "magnetic separation + chemical stabilization" is used to effectively remove impurities and reduce the activity of heavy metals; the geopolymer activation step ensures the full alkali activation reaction; and the mixing and gradient curing process control ensures the structural stability and performance consistency of the nutrient soil. The overall process is simple and easy to operate, and is suitable for large-scale production.

[0034] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge, characterized in that, The raw materials include the following parts by weight: 80-90 parts of gold tailings and tailings, 5-12 parts of geopolymer cementing system, 3-8 parts of organic nutrient components, 1-4 parts of functional regulator, and 3-6 parts of water; wherein the geopolymer cementing system is composed of an alkali activator and an aluminosilicate precursor in a mass ratio of 1:3-1:

5.

2. The high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 1, characterized in that: The gold tailings sludge has a particle size of 120-200 mesh, with SiO2 content ≥50%, Al2O3 content ≥10%, moisture content ≤5%, and pH value of 6.5-8.

5.

3. The high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 1, characterized in that: The alkaline activator is a mixture of sodium hydroxide and water glass, wherein the mass ratio of sodium hydroxide to water glass is 1:4-1:6, and the modulus of water glass is 2.0-2.

8.

4. The high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 1, characterized in that: The aluminosilicate precursor is one or a mixture of fly ash, slag, and metakaolin, and the active SiO2+Al2O3 content in the aluminosilicate precursor is ≥75%.

5. The high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 1, characterized in that: The organic nutrient component is one or more of decomposed straw, humus, and biochar, and the organic matter content of the organic nutrient component is ≥45% and the particle size is ≤3mm.

6. The high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 1, characterized in that: The functional regulator is a mixture of water-retaining agent, slow-release fertilizer, humic acid, heavy metal stabilizer, and pH adjuster in a mass ratio of 1:1:1:1 to 2:1:1:1 by mass. The water-retaining agent is a polyacrylamide-based water-retaining agent; The slow-release fertilizer is a urea-formaldehyde resin coated compound fertilizer; The heavy metal stabilizer is humic acid or phosphate rock powder. The pH adjuster is wood ash or potassium dihydrogen phosphate.

7. A method for preparing high-capacity artificial nutrient soil based on geopolymer-modified gold tailings as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) The raw materials are treated by a combination of magnetic separation and chemical stabilization: first, magnetic separation is used to remove ferromagnetic impurities, then 1-3% of the weight of gold tailings and tailings is added as a heavy metal stabilizer, and after stirring evenly, it is left to stand for 24-48 hours to reduce the activity of heavy metals; the organic nutrient components are crushed to a particle size ≤3mm and set aside. (2) Preparation of geopolymer gelation system: Mix alkali activator and aluminosilicate precursor in proportion, stir evenly and let stand for 15-30 min for activation, then set aside. (3) Mixing and stirring: First, add the pretreated gold tailings and organic nutrients to the mixer and dry mix for 8-15 minutes until the mixture is uniform; then add the geopolymer gelling system and water and wet mix for 20-30 minutes until the material is loose and free of lumps. The stirring speed is controlled at 350-500 r / min. (4) Stimulation and curing: Spread the mixture evenly on the curing site, control the ambient temperature at 22-32℃ and humidity at 65-85%, and cure for 5-10 days; keep the site sealed for the first 3 days, and turn it over once a day from the 4th to the 10th day and gradually ventilate to reduce humidity, so as to ensure uniform curing and structural stability. (5) Finished product processing: After curing, the material is crushed and passed through an 8-10 mesh sieve to remove impurities, which is the finished artificial nutrient soil.

8. The method for preparing high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 7, characterized in that: In step (1), the chemical stabilization process is adjusted according to the types of heavy metals in the gold tailings: when the lead and cadmium content is high, phosphate rock powder is preferred; when the arsenic and mercury content is high, humic acid is preferred.

9. The method for preparing high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 7, characterized in that: In step (3), 0.5-1 parts by weight of biological agent can be added during the wet mixing process to improve the nutrient conversion efficiency of the nutrient soil. The biological agent is a compound system of Bacillus subtilis and phosphate-solubilizing bacteria.

10. The method for preparing high-capacity artificial nutrient soil based on geopolymer-modified gold tailings sludge according to claim 7, characterized in that: In step (4), during the later stages of curing (7-10 days), natural air drying and ventilation can be combined to control the moisture content of the finished product at 15-20%, which is convenient for storage and transportation.