A method for preparing artificial fish reefs using gold tailings

Abstract

The invention discloses a method for preparing artificial fish reefs using gold tailings, which belongs to the field of artificial fish reef preparation. The method for preparing artificial fish reefs comprises the following steps: firstly, the gold tailings are screened to screen out fine tailings with uniform particles, and the fine tailings are cleaned by plant extract to reduce heavy metals in the fine tailings, and cleaning liquid and wet fine tailings are obtained after cleaning, and the cleaning liquid is left to stand for 1-2 days to precipitate suspended solid impurities therein, and then the impurity precipitates containing a large amount of heavy metals are removed by filtration to obtain a separation liquid, and then the wet fine tailings are mixed with P.O42.5 cement, and silica fume is added as a reinforcing agent to prepare recycled aggregate, and the recycled aggregate is cured for one week. The invention makes large-scale industrial comprehensive utilization of fine gold tailings, and can reduce the amount of cement used, reduce carbon emissions in cement production in disguised form, and reduce the production cost of artificial fish reefs.

Description

Technical Field

[0001] The invention relates to the field of artificial fish reef preparation, and in particular to a method for preparing artificial fish reefs by utilizing gold tailings. Background Art

[0002] As the largest type of industrial solid waste, tailings are stored in large quantities on the surface. Their disposal method of surface storage occupies land, destroys vegetation, pollutes the environment, poses huge safety risks, and has prominent ecological and environmental problems. It has become a governance shortcoming that cannot be ignored in the current solid waste management field. The two industries with the largest tailings production are non-ferrous metal mining and ferrous metal mining, with annual production of 460 million tons and 440 million tons respectively, and comprehensive utilization of 27.1% and 23.4% respectively.

[0003] Gold mines are one of the advantageous mineral resources in Shandong Province. Due to the particularity of mineralization, the output rate of tailings and waste rocks in the development process of gold mines is as high as 99.5%. Except for some of them being used for system filling, most of the gold tailings and waste rocks need to be stored in tailings storage and spoil dumps, which not only occupies a large amount of land and causes waste of resources, but also poses huge safety hazards. At present, the comprehensive utilization of gold tailings in Shandong Province is mainly carried out in two ways: filling and preparing building materials products; in terms of underground filling, the main method is to use coarse tailings after classification for filling, and fine tailings resources have not been effectively applied; the preparation of building materials products includes fertilizers, sintered bricks, cementitious materials, aerated concrete, geopolymers, rubber fillers, glass fibers, and microcrystalline glass, but the consumption of gold tailings in these applications is relatively small, and there is less research and application in other aspects, and there is a lack of systematic high-value bulk utilization research. The most prominent problem facing the disposal of gold tailings is the problem of large-scale utilization. At present, coarse sand (>200 mesh) is used for mine filling, with a utilization rate of 40-50%, and nearly half of the fine sand (<200 mesh) cannot be used.

[0004] The market for artificial reefs in marine ranches is huge, and a large number of artificial reefs are urgently needed. This inevitably involves the two industries of cementitious materials and aggregates used in the production of artificial reefs. Therefore, how to realize the large-scale utilization of gold tailings in the two industries of cementitious materials and aggregates, and study the feasibility of using gold tailings to prepare artificial reefs, is an urgent task to solve the problem of large-scale resource utilization of gold tailings. Summary of the invention

[0005] In order to overcome the above problems, the present invention aims to propose a method for preparing artificial fish reefs using gold tailings, with the aim of solving the problem that large-scale resource utilization of gold tailings is currently in a blank stage.

[0006] To this end, the specific technical solution adopted by the present invention is as follows:

[0007] According to one aspect of the present invention, a method for preparing an artificial fish reef using gold tailings is provided, the method for preparing an artificial fish reef comprising the following steps:

[0008] S1. First, the gold tailings are screened to screen out fine tailings with uniform particles, and then washed with plant extract to reduce heavy metals in the fine tailings, and washing liquid and wet fine tailings are obtained after washing;

[0009] S2, the cleaning liquid is allowed to stand for 1-2 days to allow the suspended solid impurities therein to settle, and then the impurity precipitates containing a large amount of heavy metals are removed by filtration to obtain a separated liquid, and then the moist fine tailings are mixed with P.O42.5 cement, and silica fume is added as a reinforcing agent to prepare the recycled aggregate, and the recycled aggregate is cured for one week;

[0010] S3, mixing the recycled aggregate prepared in S2 with P.O42.5 cement, fly ash, water and the separated liquid obtained in S2 to obtain a blank, preparing the blank into an artificial fish reef through a mold, and maintaining the artificial fish reef.

[0011] Optionally, the preparation process of the plant extract in S1 is as follows:

[0012] A mixed plant material of kelp and Masson pine needles is selected, the kelp and Masson pine needles are washed, crushed and mixed, extracted by water extraction, deionized water is added in a ratio of 1:5 - 1:8 according to the mass / volume (g / mL) ratio, that is, 5 - 8 ml of deionized water is added for every 1 gram of the mixed plant material of kelp and Masson pine needles, heated under reflux at 80 - 90°C for 2 - 3 hours, stirred continuously during the extraction process to fully dissolve the active ingredients in the plant into the water, cooled to room temperature after the extraction, and the residue is removed by filtration to obtain a plant extract.

[0013] Optionally, in S1, the specific process of cleaning the fine tailings is as follows:

[0014] The fine gold tailings are mixed with the prepared plant extract at a mass liquid-to-solid ratio of 3:1 - 5:1, and stirred at room temperature for 2 - 3 hours at a stirring speed of 20 - 30 rpm. The alginate in the kelp undergoes ion exchange and complexation reactions with the heavy metal ions in the tailings, and the polyphenols in the Masson pine form stable complexes with the heavy metals, thereby removing the heavy metals from the surface of the tailings particles and transferring them to the solution. After separating the solution from the fine tailings, a cleaning solution and moist fine tailings are obtained.

[0015] Optionally, in S2, the specific process of preparing the recycled aggregate is as follows:

[0016] The wet fine tailings are mixed in a mass ratio of 89.8% - 95%, P.O42.5 cement 4.8% - 10%, and enhancer 0.1% - 0.2%, and stirred in a forced mixer for 5 - 8 minutes at a stirring speed of 30 - 40 rpm. The mixture is then poured into a granulator, and the speed of the granulator is adjusted to 15 - 25 rpm to prepare recycled aggregate with a particle size of 2mm - 10mm. The recycled aggregate is then subjected to one-week moisture-keeping and heat-preservation maintenance.

[0017] Optionally, the mass proportion of the plant extract in the wet fine tailings is 5-30%.

[0018] Optionally, in S3, the specific steps of preparing the artificial fish reef are as follows:

[0019] Mix and stir according to the mass ratio of 60%-85% recycled aggregate, 5%-10% P.O42.5 cement, 5%-20% fly ash, and 5%-10% separation liquid and water. First, pre-mix the recycled aggregate, cement, and fly ash in a mixer for 1-2 minutes, then add the separation liquid and water, and stir for 8-12 minutes at a stirring speed of 20-30 rpm. Put the stirred materials into a mold and vibrate to form an artificial fish reef prototype. The formed artificial fish reef is cured with a film for 3 days, and then cured for at least 20 days after demolding.

[0020] Optionally, the separation liquid is mixed with water as a whole, wherein the mass of the separation liquid accounts for 20% - 40% of the total mass of the separation liquid and the water.

[0021] Optionally, in S1, the particle size of the sieved fine gold tailings is 200 mesh sieve residue ≤ 10%.

[0022] Optionally, the recycled aggregate is subjected to a one-week moisture-keeping and heat-insulating curing process, and the curing conditions are to control the temperature at 15° C.-25° C. and the humidity at 40%-80%.

[0023] Optionally, after forming, the artificial fish reef is covered with a film and cured indoors at a curing temperature of 15°C-25°C and a humidity of 40%-80%. After the artificial fish reef is demoulded, it is cured outdoors at a humidity of 60%-80%.

[0024] Compared with the prior art, this application has the following beneficial effects:

[0025] 1. In the present invention, according to the analysis of the characteristics of fine gold tailings, the fine gold tailings are prepared into recycled aggregates with a certain strength. The recycled aggregates can replace the sand and gravel aggregates in the existing concrete and reduce the amount of cement added. Shandong has a long coastline and a large demand for artificial fish reefs. The fine gold tailings produced during the gold mining process in Yantai cannot be comprehensively utilized on a large scale, resulting in a large amount of accumulation that affects the environment and has certain safety hazards. The present invention can solve this problem well, and the fine gold tailings are comprehensively utilized on a large scale in an industrialized manner. In addition, the amount of cement used can be reduced, which in disguise reduces carbon emissions in cement production and reduces the production cost of artificial fish reefs, with high economic and environmental benefits.

[0026] 2. In the treatment process of fine tailings, a mixed plant raw material of kelp and masson pine is selected to prepare a mixed plant extract, and then the fine tailings are washed with the mixed plant extract. The components such as alginate in the kelp can undergo ion exchange and complexation reactions with heavy metal ions such as lead, cadmium, mercury, etc. in the tailings. Substances such as polyphenols in masson pine can also form stable complexes with heavy metals, thereby removing heavy metals from the surface of tailings particles and transferring them to the solution. This can effectively reduce the heavy metal content in the fine tailings, thereby avoiding the problem of heavy metal leaching after the prepared artificial fish reefs are put into the sea, and improving the environmental protection of artificial fish reefs;

[0027] 3. The cleaned fine tailings not only reduce the heavy metal content, but also become moist fine tailings. When preparing recycled aggregates, there is no need to add water. It is sufficient to keep the moist fine tailings containing 5-30% of the mixed plant extract, which saves the step of mixing water in the preparation of recycled aggregates.

[0028] 4. The separated liquid obtained after precipitation treatment of the mixed plant extract of the cleaned fine tail residue is added to the formula of artificial reef preparation as a liquid with water, replacing part of the water ratio. On the one hand, it does not affect the strength of the artificial reef, while making the prepared artificial reef have the characteristics of nutrient release. Over time, the kelp components in the artificial reef will gradually decompose, releasing mannitol, amino acids and other nutrients into the surrounding seawater, providing nutrients for plankton, promoting the growth and reproduction of plankton, and then attracting more small fish, shrimps and other organisms to gather, enriching the food chain around the reef. Each kilogram of kelp components in the artificial reef can release about 5-10 grams of mannitol and 2-5 Grams of amino acids, rosin acid in Masson pine and other substances will be slowly released in seawater, have certain antibacterial properties, can prevent the excessive growth of harmful microorganisms, and will not inhibit the attachment of beneficial microorganisms. Beneficial microorganisms form biofilms on the surface of fish reefs, providing a good habitat and foraging environment for young fish. The microorganisms in the biofilm also participate in the material circulation and energy flow of the marine ecosystem. Within a week after the fish reefs are released, the number of surface microorganisms can reach 10^4-10^5 per square centimeter, and a stable biofilm community will gradually form over time. Moreover, plant extracts and their decomposition products can continue to react with some harmful substances (such as residual parts of heavy metal ions) in seawater, playing a certain role in water purification. In addition, the rich biological communities on artificial fish reefs can enhance the stability and self-repair ability of the marine ecosystem and promote the healthy development of the marine ecology. In the waters around the fish reefs, the heavy metal content in the water can be reduced by 10%-20% within three months, and the diversity of plankton can be increased by 20%-30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above characteristics, features and advantages of the present invention and their implementation methods and methods will become more clearly understood in conjunction with the following description of the embodiments, which are described in detail in conjunction with the accompanying drawings. Herein, a schematic diagram is shown:

[0030] Figure 1 The present invention is a flowchart of a method for preparing artificial fish reefs using gold tailings according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] Embodiment 1

[0033] According to an embodiment of the present invention, a method for preparing artificial fish reefs using gold tailings is provided.

[0034] The present invention is further described with reference to the accompanying drawings and specific embodiments. Figure 1 As shown, according to one embodiment of the present invention, a method for preparing an artificial fish reef using gold tailings is provided, and the method for preparing an artificial fish reef comprises the following steps:

[0035] S1. First, the gold tailings are screened to screen out fine tailings with uniform particles. The particle size of the screened fine gold tailings is 200 mesh residue ≤ 10%, and the fine tailings are washed with plant extract to reduce the heavy metals in the fine tailings. After washing, the washing liquid and wet fine tailings are obtained:

[0036] The preparation process of plant extract is as follows:

[0037] A mixed plant material of kelp and Masson pine needles is selected, the kelp and Masson pine needles are washed, crushed and mixed, extracted by water extraction, deionized water is added in a ratio of 1:5-1:8 according to the mass / volume (g / mL) ratio, that is, 5-8 ml of deionized water is added for every 1 gram of the mixed plant material of kelp and Masson pine needles, and heated and refluxed at 80-90°C for 2-3 hours. During the extraction process, stirring is continuously performed to fully dissolve the effective ingredients in the plant into the water. After the extraction is completed, the mixture is cooled to room temperature, and the residue is removed by filtering to obtain a plant extract. During the heating and reflux process, a magnetic stirrer or a mechanical stirring paddle is used for stirring, and the stirring speed is controlled at 100-150 revolutions per minute;

[0038] The specific process of cleaning fine tailings is as follows:

[0039] The fine gold tailings are mixed with the prepared plant extract at a mass liquid-to-solid ratio of 3:1 - 5:1, and stirred at room temperature for 2-3 hours at a stirring speed of 20 - 30 rpm. The alginate in the kelp undergoes ion exchange and complexation reactions with the heavy metal ions (such as lead, cadmium, mercury, etc.) in the tailings, and the polyphenols in the Masson pine form stable complexes with the heavy metals, thereby removing the heavy metals from the surface of the tailings particles and transferring them to the solution. After separating the solution from the fine tailings, a cleaning solution and moist fine tailings are obtained.

[0040] S2. The cleaning liquid is allowed to stand for 1-2 days to allow the suspended solid impurities therein to settle, and then the impurity precipitates containing a large amount of heavy metals are removed by filtration to obtain a separated liquid, and then the moist fine tailings are mixed with P.O42.5 cement, and silica fume is added as a reinforcing agent to prepare the recycled aggregate, and the recycled aggregate is cured for one week:

[0041] The specific process of recycled aggregate preparation is as follows:

[0042] The mixture is mixed in a mass ratio of 89.8% - 95% of wet fine tailings, 4.8% - 10% of P.O42.5 cement and 0.1% - 0.2% of reinforcing agent, and stirred in a forced mixer for 5 - 8 minutes at a stirring speed of 30 - 40 rpm. The mixture is then poured into a granulator, and the speed of the granulator is adjusted to 15 - 25 rpm to prepare recycled aggregate with a particle size of 2mm - 10mm. The recycled aggregate is then subjected to a one-week moisture and heat preservation curing, and the curing conditions are to control the temperature at 15℃ - 25℃ and the humidity at 40% - 80%.

[0043] The mass proportion of plant extract in the moist fine tailings is 5 - 30%.

[0044] S3, mixing the recycled aggregate prepared in S2 with P.O42.5 cement, fly ash, water and the separated liquid obtained in S2 to obtain a blank, preparing the blank into an artificial fish reef through a mold, and cultivating the artificial fish reef:

[0045] The specific steps for preparing artificial reefs are as follows:

[0046] Mix and stir according to the mass ratio of 60%-85% of recycled aggregate, 5%-10% of P.O42.5 cement, 5%-20% of fly ash, and 5%-10% of separation liquid and water. First, pre-mix the recycled aggregate, cement and fly ash in a mixer for 1-2 minutes, then add the separation liquid and water, and stir for 8-12 minutes at a stirring speed of 20-30 rpm. Put the stirred materials into a mold and vibrate to form an artificial fish reef prototype. The formed artificial fish reef is cured with a film for 3 days, and then cured for at least 20 days after demoulding. The separation liquid and water are mixed as a whole, wherein the mass of the separation liquid accounts for 20%-40% of the total mass of the separation liquid and water. After forming, the artificial fish reef with a film is cured indoors at a curing temperature of 15℃-25℃ and a humidity of 40%-80%. After demoulding, the artificial fish reef is cured outdoors at a humidity of 60%-80%.

[0047] Embodiment 2

[0048] A method for preparing an artificial fish reef using gold tailings, the method comprising the following steps:

[0049] S1. First, the gold tailings are screened to screen out fine tailings with uniform particles. The particle size of the screened fine gold tailings is 200 mesh residue ≤ 10%, and the fine tailings are washed with plant extract to reduce the heavy metals in the fine tailings. After washing, the washing liquid and wet fine tailings are obtained:

[0050] The preparation process of plant extract is as follows:

[0051] A mixed plant material of kelp and Masson pine needles was selected, the kelp and Masson pine needles were washed, crushed and mixed, extracted by water extraction, and deionized water was added at a ratio of 1:5 according to the mass / volume (g / mL) ratio, that is, 5 ml of deionized water was added for every 1 gram of the mixed plant material of kelp and Masson pine needles, and heated under reflux at 80°C for 2 hours. During the extraction process, stirring was continuously performed to fully dissolve the active ingredients in the plant into the water. After the extraction was completed, the mixture was cooled to room temperature, and the residue was removed by filtration to obtain a plant extract. During the heating and reflux process, a magnetic stirrer or a mechanical stirring paddle was used for stirring, and the stirring speed was controlled at 100 rpm:

[0052] The specific process of cleaning fine tailings is as follows:

[0053] The fine gold tailings are mixed with the prepared plant extract at a mass liquid-to-solid ratio of 3:1, and stirred at room temperature for 2 hours at a stirring speed of 20 rpm. The alginate in the kelp undergoes ion exchange and complexation reactions with the heavy metal ions (such as lead, cadmium, mercury, etc.) in the tailings, and the polyphenols in the Masson pine form stable complexes with the heavy metals, thereby removing the heavy metals from the surface of the tailings particles and transferring them to the solution. After separating the solution from the fine tailings, a cleaning solution and wet fine tailings are obtained.

[0054] S2. The cleaning liquid is allowed to stand for 1 day to allow the suspended solid impurities therein to settle, and then the impurity precipitates containing a large amount of heavy metals are removed by filtration to obtain a separated liquid, and then the moist fine tailings are mixed with P.O42.5 cement, and silica fume is added as a reinforcing agent to prepare the recycled aggregate, and the recycled aggregate is cured for one week:

[0055] The specific process of recycled aggregate preparation is as follows:

[0056] The mixture was mixed in a mass ratio of 89.8% of wet fine tailings, 4.8% of P.O42.5 cement and 0.1% of reinforcing agent, and stirred for 5 minutes with a forced mixer at a stirring speed of 30 rpm. The mixture was then poured into a granulator, and the speed of the granulator was adjusted to 15 rpm to prepare recycled aggregate with a particle size of 2 mm. The recycled aggregate was then subjected to a one-week moisture and heat preservation curing, and the curing conditions were controlled at a temperature of 15°C and a humidity of 40%.

[0057] The mass proportion of plant extract in the moist fine tailings is 5%.

[0058] S3, mixing the recycled aggregate prepared in S2 with P.O42.5 cement, fly ash, water and the separated liquid obtained in S2 to obtain a blank, preparing the blank into an artificial fish reef through a mold, and cultivating the artificial fish reef:

[0059] The specific steps for preparing artificial reefs are as follows:

[0060] Mix and stir according to the mass ratio of 60% recycled aggregate, 5% P.O42.5 cement, 5% fly ash, and 5% separation liquid and water. First, pre-mix the recycled aggregate, cement and fly ash in a mixer for 1 minute, then add the separation liquid and water, and stir for 8 minutes at a stirring speed of 20 rpm. Put the stirred materials into a mold and compact them to obtain the prototype of an artificial fish reef. The formed artificial fish reef is cured with a film for 3 days, and then cured for at least 20 days after demolding. The separation liquid is mixed with water as a whole, in which the mass of the separation liquid accounts for 20% of the total mass of the separation liquid and water. After molding, the artificial fish reef is cured with a film indoors at a curing temperature of 15°C and a humidity of 40%. After demolding, the artificial fish reef is cured outdoors at a humidity of 60%.

[0061] Embodiment 3

[0062] A method for preparing an artificial fish reef using gold tailings, the method comprising the following steps:

[0063] S1. First, the gold tailings are screened to screen out fine tailings with uniform particles. The particle size of the screened fine gold tailings is 200 mesh residue ≤ 10%, and the fine tailings are washed with plant extract to reduce the heavy metals in the fine tailings. After washing, the washing liquid and wet fine tailings are obtained:

[0064] The preparation process of plant extract is as follows:

[0065] A mixed plant material of kelp and Masson pine needles was selected, the kelp and Masson pine needles were washed, crushed and mixed, extracted by water extraction, and deionized water was added at a ratio of 1:8 according to the mass / volume (g / mL) ratio, that is, 8 ml of deionized water was added for every 1 gram of the mixed plant material of kelp and Masson pine needles, and heated under reflux at 90°C for 3 hours. During the extraction process, stirring was continued to allow the effective ingredients in the plant to be fully dissolved in the water. After the extraction was completed, the mixture was cooled to room temperature, and the residue was removed by filtration to obtain a plant extract. During the heating and reflux process, a magnetic stirrer or a mechanical stirring paddle was used for stirring, and the stirring speed was controlled at 150 rpm:

[0066] The specific process of cleaning fine tailings is as follows:

[0067] The fine gold tailings are mixed with the prepared plant extract at a mass liquid-to-solid ratio of 5:1, and stirred at room temperature for 3 hours at a stirring speed of 30 rpm. The alginate in the kelp undergoes ion exchange and complexation reactions with the heavy metal ions (such as lead, cadmium, mercury, etc.) in the tailings, and the polyphenols in the Masson pine form stable complexes with the heavy metals, thereby removing the heavy metals from the surface of the tailings particles and transferring them to the solution. After separating the solution from the fine tailings, a cleaning solution and wet fine tailings are obtained.

[0068] S2. The cleaning liquid is allowed to stand for 2 days to allow the suspended solid impurities therein to settle, and then the impurity precipitates containing a large amount of heavy metals are removed by filtration to obtain a separated liquid, and then the moist fine tailings are mixed with P.O42.5 cement, and silica fume is added as a reinforcing agent to prepare the recycled aggregate, and the recycled aggregate is cured for one week:

[0069] The specific process of recycled aggregate preparation is as follows:

[0070] The mixture was mixed in a mass ratio of 95% wet fine tailings, 10% P.O42.5 cement and 0.2% reinforcing agent, and stirred for 8 minutes using a forced mixer at a stirring speed of 40 rpm. The mixture was then poured into a granulator, and the speed of the granulator was adjusted to 25 rpm to prepare a recycled aggregate with a particle size of 10 mm. The recycled aggregate was then subjected to a one-week moisture and heat preservation curing, and the curing conditions were a temperature control of 25°C and a humidity control of 80%.

[0071] The mass proportion of plant extract in the moist fine tailings is 30%.

[0072] S3, mixing the recycled aggregate prepared in S2 with P.O42.5 cement, fly ash, water and the separated liquid obtained in S2 to obtain a blank, preparing the blank into an artificial fish reef through a mold, and cultivating the artificial fish reef:

[0073] The specific steps for preparing artificial reefs are as follows:

[0074] Mix and stir according to the mass ratio of 85% recycled aggregate, 10% P.O42.5 cement, 20% fly ash, and 10% separation liquid and water. First, pre-mix the recycled aggregate, cement and fly ash in a mixer for 2 minutes, then add the separation liquid and water, and stir for 12 minutes at a stirring speed of 30 rpm. Put the stirred materials into a mold and vibrate to form an artificial fish reef prototype. The formed artificial fish reef is cured with a film for 3 days, and then cured for at least 20 days after demolding. The separation liquid is mixed with water as a whole, in which the mass of the separation liquid accounts for 40% of the total mass of the separation liquid and water. After forming, the artificial fish reef with a film is cured indoors at a curing temperature of 25°C and a humidity of 80%. After demolding, the artificial fish reef is cured outdoors at a humidity of 80%.

[0075] Embodiment 4

[0076] During the gold tailings cleaning process, the heavy metal removal rates of different fine gold tailings and the prepared plant extract mass ratios are shown in Table 1 .

[0077] Table 1: Heavy metal removal rate of different fine gold tailings and prepared plant extracts

[0078] Solid-liquid ratio Lead removal rate (%) Cadmium removal rate (%) Mercury removal rate (%) 3:1 45 - 55 35-45 30-40 4:1 50-60 40-50 35-45 5:1 55-65 45-55 40-50

[0079] In the preparation of recycled aggregate, the effects of different tailings, cement and reinforcing agent ratios on the strength of recycled aggregate are shown in Table 2.

[0080] Table 2: Effects of different tailings, cement and reinforcing agent ratios on the strength of recycled aggregate

[0081] Moist fine tailings ratio (%) Cement ratio (%) Enhancer ratio (%) Recycled aggregate 28d compressive strength (MPa) 89.8 4.8 0.1 11-13.5 92 6 0.15 20-25 95 10 0.2 14-22

[0082] In the preparation of artificial reefs, the effects of different amounts of separation liquid added on the strength of artificial reefs are shown in Table III.

[0083] Table 3: Effect of different separation liquid addition amounts on the strength of artificial reefs

[0084] The ratio of the mass of separation liquid to the total mass of separation liquid and water (%) Artificial reef 28d compressive strength (MPa) 20 16-19 30 15-17 40 13-15

[0085] Embodiment 5

[0086] It should be noted that the method for preparing artificial fish reefs using gold tailings of the present invention uses a mixed plant extract of kelp and masson pine to clean the fine tailings, which can reduce the heavy metal content in the fine tailings. After preparing the artificial fish reefs, the heavy metal leaching of the artificial fish reefs entering the sea is reduced. The toxicity leaching procedure (TCLP) and the sulfuric acid and nitric acid method are used to detect the heavy metal leaching content of the artificial fish reefs to ensure that it meets the relevant standards, and it is concluded that the concentration of the extract, the reaction time with the tailings and the heavy metal leaching have a necessary relationship;

[0087] Concentration reasons: When the concentration of plant extract is low, there are relatively few effective ingredients that can react with heavy metals such as complexation and ion exchange, resulting in limited removal of heavy metals in tailings. As the concentration of the extract increases, the effective ingredients increase, and the contact and reaction opportunities with heavy metals increase, which can more fully dissociate heavy metals from the surface of tailings particles and fix them into the solution, thereby reducing the amount of heavy metal residues in the subsequent artificial reef preparation process and reducing the risk of leaching. However, when the concentration is too high, saturation may occur, and excess ingredients may have adverse effects on other properties of artificial reefs, such as affecting the hydration process of cementitious materials. The leaching amount of heavy metals in artificial reefs at different concentrations is shown below:

[0088] When the initial extract concentration of kelp and masson pine was 5% (mass volume ratio), the lead leaching amount of the artificial fish reef prepared was 0.5 - 0.8 mg / L, the cadmium leaching amount was 0.2 - 0.4 mg / L, and the mercury leaching amount was 0.05 - 0.1 mg / L;

[0089] When the concentration of the extract is increased to 10%, the lead leaching amount can be reduced to 0.1-0.3mg / L, the cadmium leaching amount is reduced to 0.05-0.1mg / L, and the mercury leaching amount is reduced to 0.01-0.03mg / L. This is because after the concentration is increased, the content of active ingredients such as alginate and polyphenols in the extract increases, and the combination with heavy metals is more complete;

[0090] If the concentration of the extract is further increased to 15%, although the amount of heavy metal leaching may be slightly reduced, the 28d compressive strength of the artificial reef will be reduced from the original 15-17MPa to 12-14MPa. This is because the excessively high concentration of the extract affects the hydration process of the cement, resulting in a decrease in the density of the structure.

[0091] Reaction time reason: When the tailings are mixed with the plant extract, the reaction needs a certain amount of time to reach equilibrium. A shorter reaction time may make the reaction incomplete, and the heavy metals in the tailings cannot fully react with the components in the extract and be removed. As the reaction time increases, more heavy metals can be complexed and fixed by the effective components in the extract, reducing the residue in the artificial reefs and thus reducing the leaching amount. However, if the reaction time is too long, some side reactions may occur, or the efficiency may be reduced and the cost may increase in actual production. The leaching amount of heavy metals in artificial reefs under different reaction times is as follows:

[0092] When the tailings react with the extract for 1 hour, the lead leaching amount of the artificial fish reef is 0.3-0.5mg / L, the cadmium leaching amount is 0.1-0.2mg / L, and the mercury leaching amount is 0.03-0.06mg / L;

[0093] When the reaction time is extended to 2 hours, the lead leaching amount can be reduced to 0.08 - 0.2 mg / L, the cadmium leaching amount can be reduced to 0.03 - 0.08 mg / L, and the mercury leaching amount can be reduced to 0.008 - 0.02 mg / L. This is because during the 1-2 hour extension process, the heavy metals have more time to react with the components in the extract, and more heavy metals are dissociated and fixed;

[0094] If the reaction time is extended to 3 hours, although the reduction in heavy metal leaching becomes very small and the production cycle is increased, the tailings particles may be overly refined due to long-term immersion, affecting the molding of recycled aggregates and the overall performance of artificial reefs, such as causing micro cracks in artificial reefs during maintenance, which may increase the risk of heavy metal leaching to a certain extent;

[0095] By optimizing the concentration of plant extracts and reaction time, the amount of heavy metal leaching can be effectively reduced while ensuring the performance of artificial reefs, so that they meet the requirements of relevant standards and improve the safety and eco-friendliness of artificial reefs in the marine environment.

[0096] Experimental Example 1

[0097] In the laboratory, 100 grams of artificial reef samples containing kelp components were taken and placed in a container simulating a seawater environment. The simulated seawater composition and temperature in the container were set according to the actual marine environment parameters, such as salinity of 3.2%-3.7% and temperature of 15-25℃;

[0098] High performance liquid chromatography (HPLC) was used to detect the release of mannitol. Samples were taken at intervals once a week. After filtering and diluting the samples, HPLC analysis was used to calculate the mannitol content based on the standard curve and the peak area of ​​the samples. For the detection of amino acids, an amino acid automatic analyzer was used. Samples were also taken at specified time intervals. After pretreatment steps such as hydrolysis and derivatization, the content of various amino acids was determined by the analyzer. After many experiments and data analysis, it was calculated that each kilogram of kelp in artificial reefs can release about 5-10 grams of mannitol and 2-5 grams of amino acids within one month.

[0099] Experimental Example 2

[0100] Within one week after the fish reefs were placed, a sterile sampling tool was used to collect microbial samples from the surface of the artificial fish reefs. The sampling tool (sterile cotton swab) was wiped in a designated area (1 square centimeter) on the surface of the fish reefs, and then the cotton swab was placed in a sampling tube filled with an appropriate amount of sterile saline.

[0101] The collected samples were diluted in the laboratory and inoculated onto plates containing a culture medium suitable for the growth of marine microorganisms (2216E marine bacterial culture medium). After incubation at a suitable temperature (25 - 28°C) and time (24 - 48 hours), the colonies grown on the plates were counted and the number of microorganisms per square centimeter on the surface of the fish reef was calculated based on the dilution factor. Through multiple sampling and analysis, it was found that within one week after the fish reef was released, the number of surface microorganisms could reach 10^4 - 10^5 per square centimeter.

[0102] Experimental Example 3

[0103] Heavy metal content detection

[0104] Seawater samples are collected monthly in the waters around the fish reefs and in the control waters (no artificial fish reefs). After the water samples are collected, an appropriate amount of nitric acid is immediately added to acidify and preserve them to prevent heavy metal precipitation or adsorption. After returning to the laboratory, impurities such as suspended particles in the water samples are removed by filtration;

[0105] Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the heavy metal content in water samples. ICP-MS can detect multiple heavy metal elements (such as lead, cadmium, mercury, etc.) at the same time, with high sensitivity and accuracy. By comparing the changes in heavy metal content in the waters around the fish reefs and the control waters within three months, it was calculated that the heavy metal content in the waters around the fish reefs can be reduced by 10% - 20% within three months;

[0106] Plankton biodiversity testing

[0107] Use a plankton net to conduct vertical trawling sampling in the waters around the reefs and the control area. Once a month, the collected plankton samples are fixed in formaldehyde solution and brought back to the laboratory;

[0108] In the laboratory, plankton samples were classified and identified. They were observed under an optical microscope and classified into different categories (such as diatoms, dinoflagellates, copepods, etc.) according to their morphological characteristics (such as cell shape, size, presence or absence of shell, etc.). The Shannon-Wiener Diversity Index was used to evaluate the biodiversity of plankton. The calculation formula is: ,in is the diversity index, is the number of species, It is The proportion of the number of individuals of a certain species to the total number of individuals, and by comparing the plankton biodiversity index in the waters around the fish reefs and the control waters, it was concluded that the plankton biodiversity could be increased by 20% - 30%.

[0109] Although the present invention has been disclosed as above with preferred embodiments, the embodiments are merely examples for the convenience of description and are not intended to limit the present invention. Those skilled in the art may make several changes and modifications without departing from the spirit and scope of the present invention. The scope of protection claimed by the present invention shall be based on the claims.

Claims

1. A method for preparing artificial fish reefs using gold tailings, characterized in that: The method for preparing an artificial reef comprises the following steps: S1. First, the gold tailings are screened to screen out fine tailings with uniform particles, and then washed with plant extract to reduce heavy metals in the fine tailings, and washing liquid and wet fine tailings are obtained after washing; S2, the cleaning liquid is allowed to stand for 1-2 days to allow the suspended solid impurities therein to settle, and then the impurity precipitates containing a large amount of heavy metals are removed by filtration to obtain a separated liquid, and then the moist fine tailings are mixed with P.O42.5 cement, and silica fume is added as a reinforcing agent to prepare the recycled aggregate, and the recycled aggregate is cured for one week; S3, mixing the recycled aggregate prepared in S2 with P.O42.5 cement, fly ash, water and the separated liquid obtained in S2 to obtain a blank, preparing the blank into an artificial fish reef through a mold, and maintaining the artificial fish reef.

2. A method for preparing artificial fish reefs using gold tailings according to claim 1, characterized in that: The preparation process of the plant extract in S1 is as follows: A mixed plant material of kelp and Masson pine needles is selected, the kelp and Masson pine needles are washed, crushed and mixed, extracted by water extraction, deionized water is added in a ratio of 1:5 - 1:8 according to the mass / volume (g / mL) ratio, that is, 5 - 8 ml of deionized water is added for every 1 gram of the mixed plant material of kelp and Masson pine needles, heated under reflux at 80 - 90°C for 2 - 3 hours, stirred continuously during the extraction process to fully dissolve the active ingredients in the plant into the water, cooled to room temperature after the extraction, and the residue is removed by filtration to obtain a plant extract.

3. A method for preparing artificial fish reefs using gold tailings according to claim 2, characterized in that: In S1, the specific process of cleaning the fine tailings is as follows: The fine gold tailings are mixed with the prepared plant extract at a mass liquid-to-solid ratio of 3:1 - 5:1, and stirred at room temperature for 2 - 3 hours at a stirring speed of 20 - 30 rpm. The alginate in the kelp undergoes ion exchange and complexation reactions with the heavy metal ions in the tailings, and the polyphenols in the Masson pine form stable complexes with the heavy metals, thereby removing the heavy metals from the surface of the tailings particles and transferring them to the solution. After separating the solution from the fine tailings, a cleaning solution and wet fine tailings are obtained.

4. The method for preparing artificial reefs using gold tailings according to claim 1, characterized in that: In S2, the specific process of preparing recycled aggregate is as follows: The wet fine tailings are mixed in a mass ratio of 89.8% - 95%, P.O42.5 cement 4.8% - 10%, and enhancer 0.1% - 0.2%, and stirred in a forced mixer for 5 - 8 minutes at a stirring speed of 30 - 40 rpm. The mixture is then poured into a granulator, and the speed of the granulator is adjusted to 15 - 25 rpm to prepare recycled aggregate with a particle size of 2mm - 10mm. The recycled aggregate is then subjected to one-week moisture-keeping and heat-preservation maintenance.

5. The method for preparing artificial fish reefs using gold tailings according to claim 4, characterized in that: The mass proportion of the plant extract in the wet fine tailings is 5-30%.

6. The method for preparing artificial reefs using gold tailings according to claim 1, characterized in that: In S3, the specific steps of preparing the artificial fish reef are as follows: Mix and stir according to the mass ratio of 60%-85% recycled aggregate, 5%-10% P.O42.5 cement, 5%-20% fly ash, and 5%-10% separation liquid and water. First, pre-mix the recycled aggregate, cement, and fly ash in a mixer for 1-2 minutes, then add the separation liquid and water, and stir for 8-12 minutes at a stirring speed of 20-30 rpm. Put the stirred materials into a mold and vibrate to form an artificial fish reef prototype. The formed artificial fish reef is cured with a film for 3 days, and then cured for at least 20 days after demolding.

7. The method for preparing artificial fish reefs using gold tailings according to claim 6, characterized in that: After the separation liquid is mixed with water, it is considered as a whole, wherein the mass of the separation liquid accounts for 20% - 40% of the total mass of the separation liquid and water.

8. The method for preparing artificial reefs using gold tailings according to claim 1, characterized in that: In S1, the particle size of the sieved fine gold tailings is 200 mesh sieve residue ≤ 10%.

9. The method for preparing artificial reefs using gold tailings according to claim 4, characterized in that: The recycled aggregate is subjected to a one-week moisture-keeping and heat-preservation curing process, and the curing conditions are as follows: the temperature is controlled at 15°C-25°C and the humidity is controlled at 40%-80%.

10. The method for preparing artificial fish reefs using gold tailings according to claim 6, characterized in that: After forming, the artificial fish reef is covered with a film and maintained indoors at a temperature of 15°C-25°C and a humidity of 40%-80%. After the artificial fish reef is demoulded, it is maintained outdoors at a humidity of 60%-80%.

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