Deep sea tailing disposal method

Abstract

The invention provides a deep sea tailing disposal method, and relates to the technical field of deep sea mineral resource treatment. The deep sea tailing disposal method comprises the following steps: S1, uniformly mixing tailings, a calcium-magnesium additive and water to obtain a mixture; s2, the mixed material is granulated and formed to obtain a tailing blank, and the tailing blank is subjected to an excitation curing reaction for 0.5-2 hours under the condition of 25-200 DEG C; s3, the solidified tailing blanks in the S2 are put into the seabed for treatment; wherein in the step S1, the mixture comprises the following components in parts by weight: 80-95 parts of deep sea tailings, 1-10 parts of a calcium-magnesium additive and 5-20 parts of water. According to the deep sea tailing treatment method, a tailing curing material with high compressive strength and good water resistance can be obtained without adding other gel materials, solid microparticulate matter diffusion in the tailing seabed discharging process can be avoided, and the deep sea tailing treatment method is suitable for being put into the seabed with the water depth of 1000 m or above for sealing and storage and used for seabed environment restoration after deep sea mining.

Description

Technical Field

[0001] This invention relates to the field of deep-sea mineral resource processing technology, and in particular to a method for disposing of deep-sea tailings. Background Technology

[0002] The development and utilization of mineral resources generates a large amount of tailings. While some of these tailings are used for backfilling, road construction, and building materials, most are stockpiled in tailings ponds and other similar locations. The storage and management of tailings is technically challenging and costly, occupying significant amounts of land and posing risks such as geological disasters. Seabed tailings disposal, which involves discharging tailings into the seabed without occupying land and eliminating the risk of geological disasters, has attracted considerable attention. However, current seabed tailings disposal methods involve transporting tailings in slurry form through pipelines to depths below the ocean surface or on the seabed, typically at depths of only a few hundred meters. Because tailings are generally very fine-grained, the slurry disperses widely after discharge, leading to reduced ocean turbidity, reduced light penetration, alteration of benthic habitats, burial of aquatic organisms, and even prolonged suspension of large amounts of solid particles in the seawater, posing a threat to the marine ecosystem and biodiversity. The deep ocean contains abundant mineral resources and is considered an important replacement resource for key metals in the future. Deep-sea mining and offshore processing generate a large amount of tailings. Current tailings discharge technologies are focused on discharging tailings into the ocean in the form of slurry through pipelines, which cannot avoid environmental problems caused by tailings diffusion.

[0003] The prior art CN112876147A discloses a magnesium oxide-activated slag geopolymer artificial reef and its preparation method. It uses slag as raw material and calcium and magnesium as activators (shells and magnesium oxide). The raw material slag is iron and steel industry slag (steel slag). Steel slag itself contains a large amount of dicalcium and tricalcium silicate, which has cementing properties and can be used as a cementing material. However, the amount added is large, and it is also necessary to add additives such as sodium hydroxide, gypsum, and polycarboxylic acid water-reducing agents. It is not suitable for deep-sea tailings raw materials. Moreover, the water depth where artificial reefs are placed is relatively shallow, and the compressive strength and water resistance of deep-sea tailings cannot be met. Summary of the Invention

[0004] This invention addresses the shortcomings of current deep-sea tailings disposal methods, such as the tendency for tailings to diffuse and suspend in seawater, and the inability of tailings to meet the requirements for deep-sea tailings treatment in terms of compressive strength and water resistance. It provides a deep-sea tailings disposal method that involves reacting tailings, calcium-magnesium additives, and water to solidify the tailings into spheres before releasing them into the deep seabed. This method avoids the diffusion of solid microparticles during tailings discharge into the seabed. The tailings are distributed in spheres on the seabed, which can help restore the seabed after deep-sea mining operations and promote the habitat and survival of marine life.

[0005] This invention provides a method for disposing of deep-sea tailings, comprising the following steps: S1. Mix tailings, calcium-magnesium additives and water evenly to obtain a mixture; S2. The mixture is granulated to obtain tailings billets, and the tailings billets are subjected to a solidification reaction at 25~200℃ for 0.5~2 hours to obtain solidified tailings billets; S3. The solidified tailings billets from S2 are dumped into the seabed for further processing; In S1, by weight, the mixture contains 80-95 parts deep-sea tailings, 1-10 parts calcium-magnesium additives, and 5-20 parts water.

[0006] According to the deep-sea tailings disposal method provided by the present invention, preferably, the solidified tailings billet in S3 has a compressive strength ≥1000N and a softening coefficient ≥0.85.

[0007] According to the deep-sea tailings disposal method provided by the present invention, preferably, the mixture in S2 is first ground and activated until the tailings particle size is less than or equal to 60 mesh before being granulated and formed, and preferably the grinding time is 1 to 30 minutes.

[0008] According to the deep-sea tailings disposal method provided by the present invention, preferably, the tailings billet in S2 is a spherical billet or an ellipsoidal billet, and more preferably, the particle size of the spherical billet or ellipsoidal billet is 5mm~50mm.

[0009] According to the deep-sea tailings disposal method provided by the present invention, preferably, the granulation is extrusion granulation with a pressing pressure of 10~40 MPa.

[0010] According to the deep-sea tailings disposal method provided by the present invention, preferably, the activation and solidification in S2 is to activate the solidification reaction under the conditions of temperature 60~200℃ and humidity ≥75%.

[0011] According to the deep-sea tailings disposal method provided by the present invention, preferably, the tailings are hydrometallurgical slag produced in the ore beneficiation process or a mixture of hydrometallurgical slag and mineral processing solid waste, and preferably, the ore is deep-sea polymetallic nodules and / or cobalt-rich crusts.

[0012] According to the deep-sea tailings disposal method provided by the present invention, preferably, the hydrometallurgical slag in the tailings in S2 is acid leaching slag, and the mass proportion of acid leaching slag in the mixture is ≥60%.

[0013] According to the deep-sea tailings disposal method provided by the present invention, preferably, the calcium and magnesium additive is selected from one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, calcium chloride, magnesium chloride, calcium carbonate, and magnesium carbonate, and more preferably selected from one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, and magnesium oxide.

[0014] According to the deep-sea tailings disposal method provided by the present invention, preferably, the seabed disposal depth in step S3 is greater than or equal to 1000 meters.

[0015] Beneficial effects: The deep-sea tailings disposal method provided by this invention has at least the following advantages over existing technologies: (1) The tailings are discharged into the deep seabed in the form of solidified pellets, which avoids the diffusion of tailings in the water body in the form of traditional tailings slurry discharge, and especially avoids the suspension of fine tailings in the water body. (2) By grinding and activating the tailings, calcium and magnesium additives together with water, and stimulating the tailings pellets, the active substances in the tailings and the calcium and magnesium additives are promoted to undergo a solidification reaction. The process only requires the addition of calcium and magnesium oxides or hydroxides as granulation and molding aids. There is no need to add cement, steel slag, water glass, gypsum and other cementing materials or additives. There is no high-temperature sintering process, and no elements and anions other than the major elements of seawater are introduced. The method is green, low-carbon and low-cost. (3) The consolidated pellets have high compressive strength and are suitable for being placed on the seabed at depths of more than 1,000 meters and maintaining their shape. (4) The softening coefficient of the consolidated pellets is ≥0.85, and they have good water resistance. They can maintain their shape and stability for a long time on the deep seabed. They are suitable for the restoration of the seabed environment after deep-sea mining operations and are conducive to the habitat of seabed organisms and the ecological restoration after deep-sea mining. Attached Figure Description

[0016] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the deep-sea tailings disposal method of the present invention. Detailed Implementation

[0018] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the examples, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased from legitimate channels.

[0019] In a specific embodiment, the present invention provides a method for disposing of deep-sea tailings, such as... Figure 1 As shown, it includes the following steps: S1. Mix tailings, calcium-magnesium additives and water evenly to obtain a mixture; S2. The mixture is granulated to obtain tailings billets, and the tailings billets are subjected to a solidification reaction at 25~200℃ for 0.5~2 hours to obtain solidified tailings billets; S3. The solidified tailings billets from S2 are dumped into the seabed for further processing; In S1, by weight, the mixture contains 80-95 parts deep-sea tailings, 1-10 parts calcium-magnesium additives, and 5-20 parts water.

[0020] It should be noted that: In S1, calcium and magnesium additives should not be added in excess. On the one hand, excessive addition of calcium and magnesium additives increases the processing cost; on the other hand, the role of calcium and magnesium additives is to react with the active silica of tailings (acid leaching residue) to form calcium (magnesium) silicate cementitious material. Excessive additives do not play a cementing role and are detrimental to strength and durability.

[0021] In the deep-sea tailings disposal method of this invention, amorphous active silica in the tailings (acid leaching residue) is brought into contact with calcium and magnesium additives, and a reaction is initiated at a suitable temperature to generate calcium magnesium silicate, resulting in gelation and solidification. Increased temperature is beneficial for initiating the reaction; however, excessively high temperatures cause rapid evaporation of moisture, which not only affects the reaction between the active silica and the calcium and magnesium additives but also leads to cracking of the tailings billet due to rapid water loss, thereby affecting the compressive strength of the final solidified tailings billet.

[0022] The deep-sea tailings disposal method provided by this invention involves grinding and activating tailings, calcium-magnesium additives, and water together to obtain a mixture. This mixture is then extruded and granulated, followed by activation and solidification to obtain tailings pellets suitable for long-term storage on the deep seabed. Because tailings lack hydraulic components, they are difficult to directly solidify. Therefore, traditional solidification methods require the simultaneous addition of multiple additives, and at least one or more of cement, steel slag, volcanic ash, water glass, and gypsum as binders. This involves large amounts of additives and complex processes, while water glass and gypsum have poor water resistance. This method only requires the addition of calcium-magnesium additives, i.e., oxides or hydroxides of calcium and magnesium, as molding aids. It does not introduce elements other than the essential elements in seawater and eliminates the need for cement, steel slag, water glass, gypsum, or other cementing materials. The method is low-carbon and clean. Furthermore, the tailings pellets prepared by the method of the present invention have high compressive strength and good water resistance, with a compressive strength ≥1000N and a softening coefficient ≥0.85. They are suitable for seabed storage at depths of over 1000 meters, which can prevent the diffusion of solid microparticles during the seabed discharge of tailings. The tailings are distributed on the seabed in pellet form, which can restore the seabed after deep-sea mining operations and is beneficial to the habitat and survival of marine organisms.

[0023] In some specific embodiments, the solidified tailings billet obtained by the deep-sea tailings disposal method of the present invention through steps S1 and S2 has a compressive strength ≥1000N and a softening coefficient ≥0.85.

[0024] The compressive strength is determined by the following method: the prepared (solidified tailings billet) pellets are placed in the center of the pressure plate of the pressure testing machine, the pressure testing machine is started, and pressure is applied at a pressure plate displacement speed of 10 mm / min until the pellets break. The maximum breaking load value displayed on the pressure testing machine is recorded, which is the compressive strength of the pellets.

[0025] The compressive strength of the solidified tailings billet of the present invention is ≥1000N, indicating that it has a good solidification effect, stronger structural integrity and stability, and will not have problems such as tailings diffusion when deployed in the deep sea.

[0026] The softening coefficient is defined as the ratio of a material's compressive strength in a water-saturated state to its compressive strength in a dry state. The solidified tailings billet of this invention has a softening coefficient ≥0.85, exhibiting good water resistance and maintaining good structural strength even in long-term immersion environments.

[0027] In some specific embodiments, in order to improve the reactivity of calcium and magnesium additives and enhance the compressive strength of pellets, the mixture in S2 is first ground and activated until the tailings particle size is less than or equal to 60 mesh before granulation. The preferred grinding time is 1 to 30 minutes, for example, grinding for 1 minute, 3 minutes, 5 minutes, 7 minutes, 9 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 21 minutes, 23 minutes, 25 minutes, 27 minutes, 30 minutes, or any other time range, to ensure that the required grinding particle size is achieved before granulation.

[0028] In some specific embodiments, the specific morphology of the tailings pellets mentioned in this invention can be arbitrary. Any shape of the tailings pellets after pelletizing can be collectively referred to as pellets, and any shape of the tailings pellets after activation and solidification can be collectively referred to as pellets. More preferably, they are pellets or ellipsoidal pellets, so that when the pellets are placed on the seabed, they can provide good attachment and habitat space for marine organisms, which is more conducive to marine ecological restoration. Preferably, the particle size of the pellets or ellipsoidal pellets is 5mm to 50mm. For example, the specific particle size of the pellets or ellipsoidal pellets can be a single value or any range of values ​​such as 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, and 50mm.

[0029] In some specific embodiments, in order to better achieve the strength of the compressed pellets and ensure the final activation and curing effect, the present invention also specifically limits the granulation molding to extrusion granulation, with a pressing pressure of 10~40Mpa, for example, it can be a point value of 10Mpa, 15Mpa, 20Mpa, 25Mpa, 30Mpa, 35Mpa, 40Mpa or any range of values.

[0030] In the deep-sea tailings disposal method of the present invention, the temperature rise is conducive to activating the reaction. However, if the temperature rises too quickly, the rapid evaporation of water will not only affect the reaction between the active silicon and the calcium and magnesium additives, but will also cause the tailings billet to crack due to rapid water loss, thereby affecting the compressive strength of the final solidified tailings billet.

[0031] In some specific embodiments, the activation curing mentioned in S2 of the present invention is to activate the curing reaction for 0.5 to 2 hours under the conditions of a temperature of 60 to 200°C and a humidity of ≥75%.

[0032] In some specific implementations, the activation and curing temperature can be a point value such as 60℃, 80℃, 100℃, 120℃, 150℃, 180℃, 200℃, or any range of values.

[0033] Higher temperatures help accelerate the participation of calcium and magnesium additives in the curing reaction, while a certain level of air humidity can better prevent the pellet from cracking due to excessive dehydration during the curing process, thus affecting the final compressive strength.

[0034] In some specific embodiments, for example, a temperature above 100°C can be used to activate the curing reaction in order to improve the gel curing effect and enhance the compressive strength. In schemes where the activation curing reaction temperature exceeds 100°C, it is further preferred to control the heating rate of the activation curing reaction in S2 to not exceed 5°C / min, and the residence time at 100°C to be not less than 0.5 hours. In specific embodiments, the deep-sea tailings disposal method of the present invention can be adapted to treat various tailings, especially hydrometallurgical slag or mixtures of hydrometallurgical slag and mineral processing solid waste produced in ore beneficiation processes, wherein the ore particularly refers to deep-sea polymetallic nodules and / or cobalt-rich crusts.

[0035] In some preferred embodiments, the hydrometallurgical slag produced during the ore beneficiation process mentioned in this invention specifically refers to acid leaching slag. When the tailings are a mixture of hydrometallurgical slag produced during the ore beneficiation process and mineral processing solid waste, it is preferable to control the mass percentage of acid leaching slag in the mixture to be ≥60%. The acid leaching slag has a high active silicon content, which facilitates gel solidification and pelletizing with calcium and magnesium additives.

[0036] In some specific embodiments, the calcium and magnesium additives mentioned in this invention may be selected from one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, calcium chloride, magnesium chloride, calcium carbonate, and magnesium carbonate, and more preferably, from one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, and magnesium oxide.

[0037] In some specific embodiments, the water added to the mixture in S1 of the present invention is preferably seawater.

[0038] In a specific embodiment, the deep-sea tailings disposal method provided by the present invention can solidify and shape the tailings before they can be dumped into the seabed at a depth of 1000 meters or more for treatment.

[0039] The deep-sea tailings disposal method of the present invention forms tailings into pellets with the required compressive strength, which can avoid rupture and tailings diffusion during the discharge of the pellets to the seabed, and can also restore the seabed (simulating and reproducing the seabed surface topography before seabed mining). In specific discharge, for example, pipeline discharge to the seabed can be preferred.

[0040] Example 1 A method for disposing of deep-sea tailings includes the following steps: S1. The atmospheric pressure acid leaching residue of deep-sea polymetallic nodules hydrometallurgical with a particle size of less than 60 mesh is mixed with calcium hydroxide and seawater at a mass percentage of 87%, 5%, and 8% to obtain a mixture. S2. The tailings billets are pressed into cylindrical shapes with a diameter of 20 mm and a height of 20 mm using a briquetting machine with a pressure of 10 MPa. Then, they are activated and solidified for 1 hour at 80°C and 75% humidity to obtain tailings pellets. S3. Pellet can be used for deployment to the deep seabed at depths greater than 1000 meters and for seabed restoration.

[0041] The compressive strength and softening coefficient of tailings pellets were determined using the following method.

[0042] The compressive strength is determined by the following method: the prepared (solidified tailings billet) pellets are placed in the center of the pressure plate of the pressure testing machine, the pressure testing machine is started, and pressure is applied at a pressure plate displacement speed of 10 mm / min until the pellets break. The maximum breaking load value displayed on the pressure testing machine is recorded, which is the compressive strength of the pellets.

[0043] The softening coefficient is the ratio of the compressive strength of a material in a water-saturated state to its compressive strength in a dry state.

[0044] The tailings pellets of Example 1 were measured to have a compressive strength of 1000N and a softening coefficient of 0.9. They exhibit good solidification effect, stronger structural integrity and stability, and good water resistance. They can maintain good structural strength in long-term immersion environments and will not cause problems such as tailings diffusion when deployed in the deep sea.

[0045] Example 2 A method for disposing of deep-sea tailings includes the following steps: S1. Mix the deep-sea polymetallic nodule acid leaching residue with a particle size of less than 60 mesh with calcium oxide and seawater at a mass percentage of 85%, 5%, and 10% to obtain a mixture. S2. Grind the mixture for 10 minutes, press it into spherical tailings billets with a diameter of 20 mm using a double roller briquetting machine with a pressure of 20 MPa, and then activate the solidification reaction for 1 hour at 80℃ and 75% humidity to obtain tailings pellets. S3. Pellet can be used for deployment to the deep seabed at depths greater than 1000 meters and for seabed restoration.

[0046] The compressive strength and softening coefficient of tailings pellets were determined according to the method in Example 1.

[0047] The tailings pellets of Example 2 were measured to have a compressive strength of 2000N and a softening coefficient of 0.9. They have good solidification effect, stronger structural integrity and stability, and good water resistance. They can maintain good structural strength in long-term immersion environments and will not have problems such as tailings diffusion when deployed in the deep sea.

[0048] Example 3 A method for disposing of deep-sea tailings includes the following steps: S1. The pressure acid leaching residue of deep-sea polymetallic nodules with a particle size of less than 100 mesh is mixed with calcium oxide and seawater at a mass percentage of 85%, 5%, and 10% to obtain a mixture. S2. Grind the mixture for 10 minutes, press it into spherical tailings billets with a diameter of 20 mm using a double roller briquetting machine with a pressure of 30 MPa, and then activate the solidification reaction for 1 hour at 80℃ and 75% humidity to obtain tailings pellets. S3. Pellet can be used for deployment to the deep seabed at depths greater than 1000 meters and for seabed restoration.

[0049] The compressive strength and softening coefficient of tailings pellets were determined according to the method in Example 1.

[0050] The tailings pellets of Example 3 were measured to have a compressive strength of 2500N and a softening coefficient of 0.9. They exhibit good solidification effect, stronger structural integrity and stability, and good water resistance. They can maintain good structural strength in long-term immersion environments and will not cause problems such as tailings diffusion when deployed in the deep sea.

[0051] Example 4 A method for disposing of deep-sea tailings includes the following steps: S1. The pressure acid leaching residue of deep-sea polymetallic nodules with a particle size of less than 100 mesh is mixed with calcium chloride, calcium oxide and seawater in a mass percentage of 84%, 3%, 4% and 9% respectively to obtain a mixture. S2. Grind the mixture for 10 minutes, press it into spherical tailings billets with a diameter of 30 mm using a double roller briquetting machine with a pressure of 20 MPa, and then activate the solidification reaction for 1 hour at 80℃ and 75% humidity to obtain tailings pellets. S3. Pellet can be used for deployment to the deep seabed at depths greater than 1000 meters and for seabed restoration.

[0052] The compressive strength and softening coefficient of tailings pellets were determined according to the method in Example 1.

[0053] The tailings pellets of Example 4 were measured to have a compressive strength of 2200N and a softening coefficient of 0.9. They exhibit good solidification effect, stronger structural integrity and stability, and good water resistance. They can maintain good structural strength in long-term immersion environments and will not cause problems such as tailings diffusion when deployed in the deep sea.

[0054] Example 5 A method for disposing of deep-sea tailings includes the following steps: S1. The tailings sludge and deep-sea polymetallic nodule pressure leaching residue with a particle size of less than 100 mesh carried in the polymetallic nodule collection process are mixed with magnesium hydroxide and water at a mass percentage of 20%, 65%, 5%, and 10%, respectively, to obtain a mixture. S2. Grind the mixture for 10 minutes, press it into cylindrical tailings billets with a diameter of 20 mm and a height of 20 mm using a double roller briquetting machine with a pressure of 20 MPa, and then activate and solidify it at 25℃ in an atmospheric environment for 1 hour to obtain tailings pellets. S3. Pelletized pellets can be used for seabed storage.

[0055] The compressive strength and softening coefficient of tailings pellets were determined according to the method in Example 1.

[0056] The tailings pellets of Example 2 were measured to have a compressive strength of 1500N and a softening coefficient of 0.85. They exhibited good solidification effect, stronger structural integrity and stability, and good water resistance. They could maintain good structural strength in long-term immersion environments and would not cause tailings diffusion problems when deployed in the deep sea.

[0057] Example 6 A method for disposing of deep-sea tailings includes the following steps: S1. The pressure acid leaching residue of deep-sea polymetallic nodules with a particle size of less than 100 mesh is mixed with calcium oxide and seawater at a mass percentage of 85%, 5%, and 10% to obtain a mixture. S2. Grind the mixture for 10 minutes, press it into spherical tailings billets with a diameter of 20 mm using a double roller briquetting machine with a pressure of 30 MPa, raise the temperature from room temperature to 100℃, keep it at that temperature for 0.5 h, and then continue to raise the temperature to 200℃ at a rate of 5℃ / min. Initiate the solidification reaction for 1 hour at 200℃ and 75% humidity to obtain tailings pellets. S3. Pellet can be used for deployment to the deep seabed at depths greater than 1000 meters and for seabed restoration.

[0058] The compressive strength and softening coefficient of tailings pellets were determined according to the method in Example 1.

[0059] The tailings pellets of Example 6 were measured to have a compressive strength of 2800N and a softening coefficient of 0.92. They exhibit good solidification effect, stronger structural integrity and stability, and good water resistance. They can maintain good structural strength in long-term immersion environments and will not cause problems such as tailings diffusion when deployed in the deep sea.

[0060] Example 7 A method for disposing of deep-sea tailings includes the following steps: S1. The pressure acid leaching residue of deep-sea polymetallic nodules with a particle size of less than 100 mesh is mixed with calcium oxide and seawater at a mass percentage of 85%, 5%, and 10% to obtain a mixture. S2. Grind the mixture for 10 minutes, press it into spherical tailings billets with a diameter of 20 mm using a double roller briquetting machine with a pressure of 30 MPa, directly heat it from room temperature to 200℃ at a heating rate of 10℃ / min, and activate the solidification reaction for 1 hour at 200℃ and 75% humidity to obtain tailings pellets. S3. Pellet can be used for deployment to the deep seabed at depths greater than 1000 meters and for seabed restoration.

[0061] The compressive strength and softening coefficient of tailings pellets were determined according to the method in Example 1.

[0062] The tailings pellets in Example 6 were measured to have a compressive strength of 600 N and a softening coefficient of 0.4. The excessively rapid heating rate caused cracks in the pellets, resulting in a significant decrease in both compressive strength and softening coefficient.

[0063] Comparative Example 1 A method for disposing of deep-sea tailings is basically the same as that in Example 3, except that: in S1, atmospheric pressure acid leaching residue of deep-sea polymetallic nodules hydrometallurgical with a particle size of less than 60 mesh is mixed with calcium hydroxide and seawater in proportions of 85 parts, 12 parts, and 3 parts by mass to obtain a mixture.

[0064] S2. Grind the mixture for 10 minutes, press it into spherical tailings billets with a diameter of 20 mm using a double roller briquetting machine with a pressure of 30 MPa, and then activate the solidification reaction for 1 hour at 80℃ and 75% humidity to obtain tailings pellets. The measured compressive strength of the tailings pellets is 150 N and the softening coefficient is 0.3. The pellets have low strength and cannot meet the requirements for seabed storage.

[0065] Comparative Example 2 A method for disposing of deep-sea tailings is basically the same as in Example 1, except that calcium and magnesium additives are not added: S1. The atmospheric pressure acid leaching residue of deep-sea polymetallic nodules hydrometallurgical with a particle size of less than 60 mesh is mixed with seawater at a mass percentage of 92% and 8% to obtain a mixture. S2. The mixture was pressed into cylindrical tailings billets with a diameter of 20 mm and a height of 20 mm using a 10 MPa briquetting machine. Then, the billets were activated and solidified for 1 hour at 80℃ and 75% humidity to obtain tailings pellets. The measured compressive strength of the tailings pellets was 170 N and the softening coefficient was 0.2.

[0066] The pellets have low strength and cannot meet the requirements for seabed storage.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for disposing of deep-sea tailings, characterized in that, Includes the following steps: S1. Mix tailings, calcium-magnesium additives and water evenly to obtain a mixture; S2. The mixture is granulated to obtain a tailings billet, and a solidification reaction is initiated to obtain a solidified tailings billet. The initiation and solidification range is a temperature of 25~200℃ and a reaction time of 0.5~2 hours. S3. The solidified tailings billets from S2 are dumped into the seabed for further processing; In S1, by weight, the mixture contains 80-95 parts deep-sea tailings, 1-10 parts calcium-magnesium additives, and 5-20 parts water.

2. The deep-sea tailings disposal method according to claim 1, characterized in that, The solidified tailings billet described in S3 has a compressive strength ≥1000N and a softening coefficient ≥0.

85.

3. The deep-sea tailings disposal method according to claim 1 or 2, characterized in that, The mixture described in S2 is first ground and activated until the tailings particle size is less than or equal to 60 mesh before being granulated and formed. The preferred grinding time is 1 to 30 minutes.

4. The deep-sea tailings disposal method according to any one of claims 1 to 3, characterized in that, The tailings billet mentioned in S2 is a spherical billet or an ellipsoidal billet, preferably with a particle size of 5mm to 50mm.

5. The deep-sea tailings disposal method according to claim 4, characterized in that, Granulation is performed by extrusion granulation, with a pressing pressure of 10~40 MPa.

6. The deep-sea tailings disposal method according to claims 1-5, characterized in that, The activation curing described in S2 refers to the activation curing reaction under conditions of temperature 60~200℃ and humidity ≥75%.

7. The deep-sea tailings disposal method according to any one of claims 1 to 6, characterized in that, The tailings are hydrometallurgical slag produced during the ore beneficiation process or a mixture of hydrometallurgical slag and beneficiation solid waste. Preferably, the ore is deep-sea polymetallic nodules and / or cobalt-rich crusts.

8. The deep-sea tailings disposal method according to claim 7, characterized in that, The hydrometallurgical slag in the tailings described in S2 is acid leaching slag, and the mass percentage of acid leaching slag in the mixture is ≥60%.

9. The deep-sea tailings disposal method according to any one of claims 1 to 8, characterized in that, The calcium and magnesium additive is selected from one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, calcium chloride, magnesium chloride, calcium carbonate, and magnesium carbonate, preferably selected from one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, and magnesium oxide.

10. The deep-sea tailings disposal method according to any one of claims 1 to 9, characterized in that, The seabed treatment described in S3 is carried out at a depth of 1000 meters or more.

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