Method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ore

Abstract

The invention provides a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ore, and relates to the field of deep-sea mineral resource development. The method comprises the following steps: crushing, grinding and pulping the deep-sea nickel-cobalt-manganese polymetallic ore to obtain raw ore pulp; mixing the raw ore pulp with sulfuric acid to obtain a mixture, and carrying out high-pressure acid leaching with step-by-step heating on the mixture to obtain high-temperature and high-pressure acid leaching pulp; the high-temperature and high-pressure acid leaching ore pulp is subjected to step-by-step depressurization flash evaporation concentration, and concentrated ore pulp is obtained; carrying out solid-liquid separation on the concentrated ore pulp to obtain a leaching solution and leaching residues, precipitating nickel, cobalt and manganese in the leaching solution, and carrying out solid-liquid separation to obtain a nickel-cobalt-copper enrichment and a post-precipitation solution. According to the method, ore is subjected to rough smelting processing on the sea, only target components are recycled, enriched and transported back to the land for smelting, the transportation amount is reduced, most useless components are backfilled to the seabed after being cured, and the seabed after deep sea mining can be repaired easily.

Description

Technical Field

[0001] This application relates to the field of deep-sea mineral resource development, and in particular to a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ore. Background Technology

[0002] Nickel and cobalt are important raw materials for lithium batteries and high-performance alloys. The deep sea contains abundant metallic mineral resources, among which polymetallic nodules and cobalt-rich iron-manganese crusts contain key metallic elements such as nickel, cobalt, and copper. These are currently the most widely distributed and largest-quantity known seabed polymetallic oxide ores, and are important sources of nickel and cobalt for future deep-sea development. These deep-sea polymetallic oxide ores are characterized by polymetallic association, high water content, and low nickel and cobalt grades. In addition to nickel, cobalt, and copper, they also contain large amounts of iron and manganese. Due to the complex mineral distribution characteristics, direct beneficiation makes it difficult to separate and enrich nickel, cobalt, and copper. Existing publicly available beneficiation and processing schemes involve shipping this high-water-content, low-grade oxide ore by sea to ports and then transporting it to smelters for processing. This results in large transportation volumes, high transportation costs, and large amounts of tailings occupying land, limiting the economic viability of its processing.

[0003] Therefore, there is an urgent need to provide a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores to solve the above problems. Summary of the Invention

[0004] The purpose of this application is to provide a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application provides a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores, comprising: Deep-sea nickel-cobalt-manganese polymetallic ore is crushed, ground, and pulped to obtain raw ore pulp; The raw ore slurry is mixed with sulfuric acid to obtain a mixture, and the mixture is subjected to high-pressure acid leaching with progressively increasing temperature to obtain a high-temperature and high-pressure acid leaching slurry. The high-temperature and high-pressure acid leaching slurry is subjected to flash concentration with progressively decreasing pressure to obtain a concentrated slurry; The concentrated slurry is subjected to solid-liquid separation to obtain leachate and leaching residue. Nickel, cobalt and manganese in the leachate are precipitated and separated into solid and liquid components to obtain nickel-cobalt-copper enrichment and precipitated liquid.

[0006] Optionally, the method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The deep-sea nickel-cobalt-manganese polymetallic deposit includes seafloor polymetallic nodules and / or seafloor cobalt-rich crusts; (2) The deep-sea nickel-cobalt-manganese polymetallic ore contains 15% to 30% manganese by mass, 0.3% to 1.5% nickel by mass, 0.15% to 1% cobalt by mass, 0.15% to 1.5% copper by mass, and 5% to 20% iron by mass. (3) More than 70% of the raw ore slurry has a particle size of less than 0.074 mm.

[0007] Optionally, the method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The mass of the sulfuric acid is 0.25-0.55 times the mass of the deep-sea nickel-cobalt-manganese polymetallic ore; (2) The high-pressure acid leaching temperature is 150-280℃, the pressure is 0.4-6.5Mpa, and the time is 5-60 minutes.

[0008] Optionally, the high-pressure acid leaching temperature is 230-280℃, the pressure is 2.5-6.5 MPa, and the time is 5-30 minutes.

[0009] Optionally, high-pressure acid leaching can be carried out in a tubular reactor; The tubular reactor includes a continuous reactor with a length-to-diameter ratio ≥500; The slurry flow rate in the tubular reactor is 1-3 m / s.

[0010] Optionally, the flash concentration includes concentrating the high-temperature and high-pressure acid leaching slurry through three or more flash stages and cooling it to 100°C.

[0011] Optionally, the leaching residue is subjected to magnetic separation to obtain magnetic and non-magnetic products, and the non-magnetic products are then treated to render them harmless before being discharged into the seabed. The harmless treatment includes: dehydrating the non-magnetic product to obtain dehydrated leaching residue, mixing the dehydrated leaching residue with calcium and magnesium additives, grinding and rolling to obtain slag blanks. The slag blank is subjected to activation and solidification treatment to obtain tailings pellets.

[0012] Optionally, the method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The water content of the dehydrated leachate is 10-20%; (2) The polishing time is 1-30 min; (3) The calcium and magnesium additives include one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, calcium chloride, and magnesium chloride; (4) The mass of the calcium and magnesium additive is 2-10% of the mass of the dehydrated leaching residue; (5) The particle size of the slag blank is 10-50 mm; (6) The pressure of the roller pressing is 10-40 MPa; (7) The temperature for the activation and curing treatment is 25-200℃, and the time is 0.5-2h; (8) The compressive strength of the tailings pellets is ≥1000N and the softening coefficient is ≥0.85; (9) The depth of the seabed is greater than or equal to 1000 meters.

[0013] Optionally, the method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The total mass content of nickel, cobalt and copper in the nickel-cobalt-copper enrichment is ≥30%; (2) The precipitated liquid is returned to the pulping process; (3) The flash vapor obtained from the flash concentration is returned to the pulping process; (4) The precipitate includes chemical precipitation and / or electrochemical precipitation.

[0014] Optionally, the method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The leachate and the ground deep-sea nickel-cobalt-manganese polymetallic ore are mixed, pre-leached under normal pressure, and separated into solid and liquid to obtain a leachate under normal pressure and a pre-leached residue. The pre-leached residue is then pulped. The atmospheric pressure leachate undergoes the precipitation process; The acid concentration in the atmospheric pressure leachate is ≤15g / L; The temperature for the atmospheric pressure pre-impregnation is 50-100℃, and the time is 5-30 minutes; (2) The raw ore slurry is preheated to obtain a preheated slurry; The flash vapor obtained from flash concentration is returned to the preheating process.

[0015] Compared with the prior art, the beneficial effects of this application include: The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores provided in this application involves initial offshore smelting of the ore to obtain highly enriched nickel, cobalt, and copper concentrates, significantly reducing transportation volume. Simultaneously, most of the useless components are solidified and disposed of for backfilling on the seabed, contributing to seabed restoration after deep-sea mining. After crushing and fine grinding, the deep-sea nickel-cobalt polymetallic oxide ore is mixed with appropriate amounts of water and sulfuric acid to prepare a slurry. Without the addition of reducing agents or other auxiliaries, highly selective leaching of key metals such as nickel, cobalt, and copper is achieved through high-pressure acid leaching with progressively increasing temperatures, effectively suppressing manganese in the leaching residue. This method involves the initial refining of ore at sea, recovering and enriching only the target components before transporting them back to land for smelting, thus reducing transportation volume. Furthermore, most of the useless components are solidified and backfilled into the seabed, contributing to seabed restoration after deep-sea mining. This method is used for the initial beneficiation and smelting of deep-sea nickel-cobalt-manganese polymetallic ore at sea, obtaining highly enriched nickel-cobalt concentrates. These concentrates are then transported to land for further processing, while the leaching residue is backfilled into the seabed. This not only helps reduce the overall cost of developing and utilizing deep-sea nickel-cobalt-manganese polymetallic ore but also helps mitigate the impact of seabed mining on the seabed environment and ecology. This method specifically addresses key constraints faced by offshore smelting, such as the extreme marine environment, platform turbulence and limited space, inconvenient energy and auxiliary material supply, and the safe disposal and discharge of tailings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0017] Figure 1 This is a schematic diagram of the process for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores provided in Example 1; Figure 2 This is a schematic diagram of the process for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores provided in Example 3. Detailed Implementation

[0018] First, the solution provided in this application will be explained in more detail as follows: This application provides a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores, including: Deep-sea nickel-cobalt-manganese polymetallic ore is crushed, ground, and pulped to obtain raw ore pulp; The raw ore slurry is mixed with sulfuric acid to obtain a mixture, and the mixture is subjected to high-pressure acid leaching with progressively increasing temperature to obtain a high-temperature and high-pressure acid leaching slurry. It is important to note that during high-pressure acid leaching, nickel, cobalt, and copper are selectively leached into the solution, while iron and manganese are suppressed in the slag within the high-temperature, high-pressure acid leaching slurry. In deep-sea nickel-cobalt-manganese polymetallic oxide ores, the manganese minerals are mainly manganese ore, naphthosite, and hydroxymanganite. Among them, manganese ore has the highest degree of crystallinity and the most stable structure, with strong Mn-O bonds, making it difficult to be eroded by strong acids. However, under high-temperature, high-pressure, and strong acid conditions, manganese ore transforms into naphthosite and hydroxymanganite. Hydroxymanganite has a poor degree of crystallinity and weaker Mn-O bonds, making it more susceptible to leaching by high-temperature, strong acid erosion. This application employs a high-pressure acid leaching method with progressively increasing temperature. In the initial stage of leaching, although the acidity is high, the temperature is low, and most manganese exists in the form of calcium manganese ore, thus inhibiting manganese dissolution. As leaching progresses, the pulp temperature rises, and although the calcium manganese ore transforms into hydrous manganese ore, the pulp acidity simultaneously decreases, reducing the probability of hydrous manganese ore being eroded and dissolved. Furthermore, the transformation of manganese minerals facilitates the more thorough release and leaching of nickel, cobalt, and copper from the manganese minerals. This achieves efficient leaching of nickel, cobalt, and copper while reducing the dissolution of manganese and iron, achieving selective leaching of nickel, cobalt, and copper, and directionally controlling manganese to the leaching residue. In practice, the prepared pulp can be preheated using low-temperature flash steam generated by the flash evaporation of the high-temperature, high-pressure acid leaching pulp. Then, medium-temperature flash steam, high-temperature flash steam generated by flash evaporation, and high-temperature steam introduced from the outside are used to progressively heat the pulp in the tubular leaching process, completing the leaching process. Flash steam and high-temperature steam can be used to heat the ore slurry through direct or indirect heat exchange. Direct heating involves directly introducing steam into the ore slurry, while indirect heating uses a shell-and-tube heat exchanger. Flash steam heating is preferred for direct heating, while high-temperature steam heating is preferred for indirect heating, with the leaching slurry and steam flowing in opposite directions.

[0019] The high-temperature and high-pressure acid leaching slurry is subjected to flash concentration with progressively decreasing pressure to obtain a concentrated slurry; In some embodiments, the high-temperature and high-pressure acid leaching slurry enters a multi-stage series flash evaporation self-concentrator for flash concentration. The slurry temperature is reduced to below 100°C through stepwise pressure reduction. The water in the slurry is rapidly evaporated by the sudden drop in slurry pressure to obtain concentrated slurry. It is important to note that by using a stepped flash evaporation with progressively decreasing pressure, the heat in the high-temperature, high-pressure slurry can be fully utilized, and the evaporation rate can be increased to achieve the purpose of slurry concentration. To improve the evaporation concentration effect and the thermal energy utilization rate of the high-temperature slurry, it is preferable to use three or more stages of equal enthalpy drop flash evaporation in practice. Specifically: the first stage of flash evaporation produces high-temperature flash steam; the intermediate stage of flash evaporation produces medium-temperature flash steam; and the final stage of flash evaporation reduces the slurry temperature to atmospheric pressure below the boiling point of the solution and produces low-temperature steam. The concentrated slurry is then subjected to solid-liquid separation to obtain leachate and leachate residue. The nickel, cobalt, and manganese in the leachate are precipitated and separated into solid and liquid components to obtain nickel-cobalt-copper enriched material and a post-precipitation liquid.

[0020] In some embodiments, deep-sea nickel-cobalt-manganese polymetallic ore is crushed and finely ground, then mixed with an appropriate amount of water and sulfuric acid to prepare a slurry. The slurry is continuously pumped into a pipeline reactor using a diaphragm pump. The slurry is heated to a set temperature step by step in the pipeline reactor and subjected to high-temperature and high-pressure acid leaching at the set temperature. Then, the slurry enters a flash evaporator for thickening. The flash steam generated during flash evaporation is returned to the slurry for preheating and heating the leaching slurry. The thickened slurry from the flash evaporator is subjected to solid-liquid separation to obtain a leaching solution rich in nickel and cobalt and a leaching residue rich in manganese and iron. The leaching solution is precipitated to obtain nickel-cobalt enriched material, which is transported to an onshore smelter for further processing into nickel and cobalt products. The leaching residue is stabilized and solidified before being backfilled onto the seabed.

[0021] It should be noted that offshore smelting faces multiple technical obstacles compared to onshore smelting, including but not limited to: (1) limited platforms and space, making it impossible to accommodate single large-scale equipment; (2) the contradiction between the high-density load of smelting equipment and the load balance of the ship platform; (3) the safety risks of the ship platform swaying (rolling, pitching, heaving) affecting the uniform distribution of materials, melt splashing, and load imbalance in large cavity reactors (such as smelting furnaces, stirring tanks, etc.); and (4) the disposal and discharge of smelting tailings. This application uses a pipeline reactor for high-temperature and high-pressure acid leaching. The pipeline reactor is easy to configure and integrate flexibly according to the load balance requirements of the ship platform; the material in the pipeline is full and will not be affected by the swaying of the ship platform; the pipeline reactor is sealed, safe and reliable without mechanical stirring; for smelting tailings, the active silica formed and retained in the slag during the high-pressure acid leaching process is used, and a small amount of calcium and magnesium additives are added for solidification, so as to achieve harmless disposal and discharge into the deep-sea mining area for seabed remediation.

[0022] In some embodiments, the method for offshore smelting and processing deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The deep-sea nickel-cobalt-manganese polymetallic deposit includes seafloor polymetallic nodules and / or seafloor cobalt-rich crusts; (2) The deep-sea nickel-cobalt-manganese polymetallic ore contains 15% to 30% manganese by mass, 0.3% to 1.5% nickel by mass, 0.15% to 1% cobalt by mass, 0.15% to 1.5% copper by mass, and 5% to 20% iron by mass. Optionally, the mass content of manganese in the deep-sea nickel-cobalt-manganese polymetallic ore can be any value between 15%, 20%, 25%, 30%, or 15-30%; the mass content of nickel can be any value between 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, or 0.3%-1.5%; the mass content of cobalt can be any value between 0.15%, 0.5%, 1%, or 0.15%-1%; the mass content of copper can be any value between 0.15%, 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, or 0.15%-1.5%; and the mass content of iron can be any value between 5%, 10%, 15%, 20%, or 5-20%. It is important to note that deep-sea nickel-cobalt-manganese polymetallic ores are characterized by polymetallic association and low grade. Besides nickel, cobalt, and copper, they also contain significant amounts of iron and manganese, with the total content of nickel, cobalt, and copper being approximately 1%–3%, and manganese content approximately 15%–30%. No similar ore has been discovered or used for production on land to date. Nickel, cobalt, and copper are hosted in the iron-manganese mineral phase of the ore, and physical beneficiation methods cannot separate and enrich them, necessitating direct smelting. The challenge of hydrometallurgical processes is how to achieve the dissociation of nickel, cobalt, and copper from the iron-manganese minerals and their selective and efficient leaching with sulfuric acid, while avoiding the leaching of manganese and iron. (3) More than 70% of the raw ore slurry has a particle size of less than 0.074 mm.

[0023] Optionally, the proportion of material particles with a particle size of less than 0.074 mm in the raw ore slurry can be any value of 71%, 75%, 80%, 85%, 90%, 95%, or greater than 70%.

[0024] In some embodiments, the method for offshore smelting and processing deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The mass of the sulfuric acid is 0.25-0.55 times the mass of the deep-sea nickel-cobalt-manganese polymetallic ore; Optionally, the mass of sulfuric acid can be any value between 0.25, 0.3, 0.4, 0.5, 0.55, or 0.25-0.55 times the mass of the deep-sea nickel-cobalt-manganese polymetallic ore. (2) The high-pressure acid leaching temperature is 150-280℃, the pressure is 0.4-6.5Mpa, and the time is 5-60 minutes.

[0025] Optionally, the high-pressure acid leaching temperature can be any value between 150℃, 180℃, 200℃, 240℃, 280℃, or 150-280℃; the pressure can be any value between 0.4 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 6.5 MPa, or 0.4-6.5 MPa; and the time can be any value between 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, or 5-60 minutes.

[0026] It is important to note that the parameters of high-pressure acid leaching are controlled by setting the length of the tubular reactor and the slurry flow rate. Increasing the leaching temperature helps to accelerate the leaching reaction rate, shorten the leaching time, and increase the leaching rate of nickel, cobalt, and copper. In the high-pressure acid leaching process of this application, it is not necessary to introduce air, oxygen, or other gases for leaching assistance. The leaching pressure is the saturated vapor pressure of water at the corresponding leaching temperature, and it is not necessary to specifically adjust the pressure. However, if the leaching temperature is too high, it will not only increase the smelting energy consumption, but also lead to a significant increase in leaching pressure, resulting in increased pressure resistance of the leaching pipeline and increased investment. Leaching time is the time required to complete the leaching reaction, i.e., the residence time of the mixed slurry of nickel-cobalt-manganese polymetallic ore and sulfuric acid solution in a tubular reactor. Under certain conditions, extending the leaching time is beneficial to improving the leaching rate. The residence time of the slurry in the tubular reactor is related to the pipe length and the slurry flow rate. A slower flow rate can extend the residence time, but too slow a flow rate will affect slurry mixing and easily cause pipe blockage; extending the pipe will lead to increased investment. The required reaction time can be reduced by appropriately increasing the reaction temperature, thereby shortening the required pipe length.

[0027] In some embodiments, the high-pressure acid leaching temperature is 230-280°C, the pressure is 2.5-6.5 MPa, and the time is 5-30 minutes.

[0028] Optionally, the high-pressure acid leaching temperature can be any value between 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, or 230-280℃; the pressure can be any value between 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 6 MPa, 6.5 MPa, or 2.5-6.5 MPa; and the time can be any value between 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or 5-30 minutes.

[0029] It is important to note that high-pressure acid leaching increases the leaching temperature and pressure, significantly shortening the leaching time. At temperatures above 250°C, the leaching time is less than 10 minutes, facilitating the use of pipeline reactors. Pipeline reactors are used as leaching equipment for high-pressure acid leaching because they do not have internal mechanical stirring devices during the slurry's movement, resulting in low power consumption. In particular, pipeline equipment is highly adaptable to the turbulence of offshore platforms and confined spaces.

[0030] In some embodiments, high-pressure acid leaching is performed in a tubular reactor; The tubular reactor includes a continuous reactor with a length-to-diameter ratio ≥500; Optionally, the length-to-diameter ratio of the tubular reactor can be 500, 600, 700, 800, 900, 1000 or any value greater than or equal to 500; The slurry flow rate in the tubular reactor is 1-3 m / s.

[0031] Optionally, the slurry flow rate in the tubular reactor can be any value between 1 m / s, 2 m / s, 3 m / s, or 1-3 m / s.

[0032] It should be noted that there is no mechanical stirring device in the reactor; the slurry is mixed by the turbulence generated by the rapid flow of the slurry. In some embodiments, the flash concentration includes concentrating the high-temperature, high-pressure acid leaching slurry through three or more stages of flash evaporation and cooling it to 100°C. In some embodiments, the leaching residue is subjected to magnetic separation to obtain magnetic and non-magnetic products, and the non-magnetic products are then treated to render them harmless before being discharged into the seabed. The harmless treatment includes: dehydrating the non-magnetic product to obtain dehydrated leaching residue, mixing the dehydrated leaching residue with calcium and magnesium additives, grinding and rolling to obtain slag blanks. The slag blank is subjected to activation and solidification treatment to obtain tailings pellets.

[0033] It should be noted that the tailings pellets meet the requirements of being discharged into the deep seabed at a depth of more than 1,000 meters and stored in pellet form on the seabed.

[0034] In some embodiments, the method for offshore smelting and processing deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The water content of the dehydrated leachate is 10-20%; Optionally, the moisture content of the dehydrated leachate can be any value between 10%, 15%, 20%, or 10-20%. (2) The polishing time is 1-30 min; Optionally, the wetting time can be any value between 1 min, 5 min, 10 min, 20 min, 30 min, or 1-30 min; (3) The calcium and magnesium additives include one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, calcium chloride, and magnesium chloride; It should be noted that after high-temperature and high-pressure acid leaching, the silicon-containing minerals in the deep-sea nickel-cobalt-manganese polymetallic ore are transformed into amorphous active silica and remain in the acid leaching residue. The calcium and magnesium ions in the calcium-magnesium additive react with the amorphous silica in the residue to form calcium-magnesium silicate, which produces a gelling and solidification effect. (4) The mass of the calcium and magnesium additive is 2-10% of the mass of the dehydrated leaching residue; Optionally, the mass of the calcium and magnesium adjuvant can be any value between 2%, 4%, 6%, 8%, 10% or 2-10% of the mass of the dehydrated leachate. (5) The particle size of the slag blank is 10-50 mm; Optionally, the particle size of the slag flakes can be any value between 10mm, 20mm, 30mm, 40mm, 50mm or 10-50mm; (6) The pressure of the roller pressing is 10-40 MPa; Optionally, the pressure of the roller can be any value between 10 MPa, 20 MPa, 30 MPa, 40 MPa or 10-40 MPa; (7) The temperature for the activation and curing treatment is 25-200℃, and the time is 0.5-2h; Optionally, the temperature for the activation and curing treatment can be any value between 25℃, 50℃, 100℃, 150℃, 200℃ or 25-200℃, and the time can be any value between 0.5h, 1h, 1.5h, 2h or 0.5-2h. (8) The compressive strength of the tailings pellets is ≥1000N and the softening coefficient is ≥0.85; Optionally, the compressive strength of the tailings pellets can be any value of 1000 N, 1500 N, 2000 N, 3000 N or ≥1000 N, and the softening coefficient can be any value of 0.85, 0.9, 0.95 or ≥0.85. (9) The depth of the seabed is greater than or equal to 1000 meters.

[0035] Optionally, the depth of the seabed can be any value of 1000 meters, 1500 meters, 2000 meters, 3000 meters, 4000 meters, 5000 meters, 6000 meters or greater than or equal to 1000 meters.

[0036] In some embodiments, the method for offshore smelting and processing deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The total mass content of nickel, cobalt and copper in the nickel-cobalt-copper enrichment is ≥30%; Optionally, the total mass content of nickel, cobalt and copper in the nickel-cobalt-copper concentrate can be any value of 30%, 40%, 50%, 60%, 70%, 80% or ≥30%; It should be noted that nickel-cobalt-copper concentrates can be sold as products or transported back to onshore smelters for further refining. (2) The precipitated liquid is returned to the pulping process; (3) The precipitate includes chemical precipitation and / or electrochemical precipitation.

[0037] In some embodiments, electrochemical precipitation includes electrolytic deposition.

[0038] In some embodiments, the method for offshore smelting and processing deep-sea nickel-cobalt-manganese polymetallic ores satisfies at least one of the following conditions: (1) The leachate and the ground deep-sea nickel-cobalt-manganese polymetallic ore are mixed, pre-leached under normal pressure, and separated into solid and liquid to obtain a leachate under normal pressure and a pre-leached residue. The pre-leached residue is then pulped. The atmospheric pressure leachate undergoes the precipitation process; It should be noted that after the high-temperature and high-pressure acid leaching slurry is concentrated by flash evaporation and solid-liquid separation, the residual acid concentration in the leachate is increased. The leachate can be used for atmospheric pressure pre-leaching of deep-sea nickel-cobalt-manganese polymetallic ore after grinding to improve the utilization rate of acid. The pre-leaching residue after atmospheric pressure pre-leaching is then used to prepare slurry, and then subjected to high-pressure acid leaching. The atmospheric pressure leachate obtained from atmospheric pressure pre-leaching is used for precipitation and enrichment of nickel, cobalt and copper. The acid concentration in the atmospheric pressure leachate is ≤15g / L; Optionally, the acid concentration in the atmospheric pressure leachate can be any value of 1 g / L, 5 g / L, 10 g / L, 15 g / L or ≤15 g / L; The temperature for the atmospheric pressure pre-impregnation is 50-100℃, and the time is 5-30 minutes; Optionally, the temperature for atmospheric pressure pre-impregnation can be any value between 50℃, 60℃, 70℃, 80℃, 90℃, 100℃ or 50-100℃, and the time can be any value between 5 minutes, 10 minutes, 20 minutes, 30 minutes or 5-30 minutes. (2) The raw ore slurry is preheated to obtain a preheated slurry; The flash vapor obtained from flash concentration is returned to the preheating process.

[0039] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0040] Example 1 This embodiment provides a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores, the process of which is shown in the diagram below. Figure 1 As shown, the specific process steps are as follows: A polymetallic nodule ore from the seabed, containing 1.05% nickel, 0.20% cobalt, 0.86% copper, 7.18% iron, and 24.64% manganese, was crushed and finely ground until over 80% of the particles were less than 0.074 mm. A slurry was prepared by mixing water and deep-sea nickel-cobalt-manganese polymetallic ore at a mass ratio of 3:1. The slurry was preheated to 95°C. Then, sulfuric acid and the slurry were transferred to a tubular reactor (a continuous reactor with an aspect ratio ≥500 and a slurry flow rate of 1.2 m / s) at a mass ratio of 0.45:1. The temperature was gradually increased to 250°C. The process should last for 10 minutes at a pressure of 4.0 MPa; then, a three-stage flash concentration is performed. After the third stage of flash concentration, the slurry temperature is 100℃, and the evaporation rate is 30%. Subsequently, solid-liquid separation is carried out to obtain a leachate with a residual acid concentration of 70 g / L, rich in nickel, cobalt, and copper, and a high-pressure acid leaching residue (leaching residue) rich in manganese and iron. The sulfuric acid concentration in the leachate is 71.5 g / L, and the concentrations of nickel, cobalt, copper, and manganese are 4.88 g / L, 0.88 g / L, 3.94 g / L, and 1.59 g / L, respectively. The steam generated during the flash concentration process is returned to the preparation of the preheated slurry and the high-temperature and high-pressure acid leaching step. The leaching solution was adjusted to pH 3 at 70℃ by adding 10% sodium hydroxide solution to remove impurity ions such as iron and aluminum. The pH of the solution was then adjusted to pH 8 at 10% sodium hydroxide solution. The precipitation reaction time was 0.5 hours, and more than 95% of the nickel and cobalt were precipitated to form a nickel-cobalt-copper enrichment and a post-precipitation solution, resulting in a nickel-cobalt-copper enrichment with a total nickel-cobalt-copper content of 38.9%. The post-precipitation solution was returned to the slurry preparation step. Manganese is recovered from the high-pressure acid leaching residue by magnetic separation, yielding manganese-rich slag and non-magnetic tailings. Non-magnetic tailings are dehydrated to a moisture content of 10%, and calcium hydroxide is added at 5% of the tailings mass. After being mixed by grinding, the mixture is pressed into 30mm slag blanks, and then solidified at 120℃ for 1 hour to obtain tailings pellets with a compressive strength of 1800N and a softening coefficient of 0.87. These pellets meet the requirements for discharge into the deep seabed at a depth of more than 1000 meters and for storage on the seabed in pellet form.

[0041] In this method, the leaching rates of nickel, cobalt, copper, iron and manganese were 97.50%, 92.25%, 96.32%, 6.5% and 4.65%, respectively, and the sulfuric acid utilization rate was 66.7%.

[0042] Example 2 This embodiment provides a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores, and the specific process steps are as follows: A cobalt-rich seabed crust ore containing 0.24% nickel, 0.47% cobalt, 0.13% copper, 19.17% iron, and 15.67% manganese is crushed and finely ground until more than 80% of the particles are smaller than 0.074 mm. A slurry is prepared by mixing water and deep-sea nickel-cobalt-manganese polymetallic ore at a mass ratio of 4:1. The slurry is then continuously pumped into a tubular reactor (a continuous reactor with an aspect ratio ≥500 and a slurry flow rate of 1 m / s) using a diaphragm pump. A metered sulfuric acid pump is also used to deliver the slurry into the tubular reactor. In the apparatus, sulfuric acid and deep-sea nickel-cobalt-manganese polymetallic ore are mixed at a mass ratio of 0.4:1. The temperature is raised to 190℃, and the slurry is kept at this temperature for a total of 30 minutes under a pressure of 1.3 MPa. Then, flash concentration is performed. After flash concentration and pressure reduction, the slurry temperature is 100℃, and the evaporation rate is 17%. Subsequently, solid-liquid separation is performed to obtain a leaching solution rich in nickel, cobalt, and copper, and a high-pressure acid leaching residue (leaching residue) rich in manganese and iron. The steam generated during the flash concentration process is returned to the preheating and slurry preparation steps. The leaching solution was adjusted to pH 2.8 at 70℃ by adding 10% sodium hydroxide solution to remove impurity ions such as iron and aluminum. The pH of the solution was then adjusted to pH 7.5 at 10% sodium hydroxide solution. The precipitation reaction time was 0.5 hours, and more than 90% of the nickel and cobalt were precipitated to form a nickel-cobalt-copper concentrate and a post-precipitation solution. The total nickel-cobalt-copper content in the concentrate was 36.9%. The post-precipitation solution was returned to the pulp preparation step. Manganese is recovered from the high-pressure acid leaching residue by magnetic separation, yielding manganese-rich slag and non-magnetic tailings. Non-magnetic tailings are dehydrated to a moisture content of 10%, and calcium hydroxide is added at 5% of the tailings mass. After being mixed by grinding, the mixture is pressed into 30mm slag blanks, and then solidified at 120℃ for 1 hour to obtain tailings pellets with a compressive strength of 1500N and a softening coefficient of 0.86. These pellets meet the requirements for discharge into the deep seabed at a depth of more than 1000 meters and for storage on the seabed in pellet form.

[0043] The leaching rates of nickel, cobalt, copper, iron and manganese in this method were 95.0%, 91.3%, 91.5%, 9.1% and 8.7%, respectively, achieving efficient one-step separation and extraction of nickel, cobalt and copper.

[0044] Example 3 This embodiment provides a method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores, with the specific process illustrated below. Figure 2 As shown, the steps are as follows: Based on Example 1, a portion of the obtained leachate was mixed with more than 80% of the seabed polymetallic nodules that were finely ground to a particle size of less than 0.074 mm at a liquid-to-solid mass ratio of 2:1. The mixture was leached at 70°C and atmospheric pressure for 30 minutes, followed by solid-liquid separation to obtain an atmospheric pressure leachate with a residual acid concentration of 12 g / L and an atmospheric pressure leachate residue. The sulfuric acid utilization rate was 94.5%. At 70℃, 10% sodium hydroxide solution was added dropwise to the normal pressure leachate to adjust the pH of the leachate to 3 at the endpoint to remove impurity ions such as iron and aluminum. Then, the solution was subjected to electrochemical precipitation to obtain a nickel-cobalt-copper enrichment with a total nickel-cobalt-copper content of more than 60%.

[0045] Comparative Example 1 The difference from Example 1 is that, instead of a step-by-step high-pressure acid leaching process, the raw ore slurry is directly mixed with sulfuric acid, followed by high-temperature and high-pressure acid leaching. That is: A polymetallic nodule ore from the seabed containing 1.05% nickel, 0.20% cobalt, 0.86% copper, 7.18% iron, and 24.64% manganese was crushed and finely ground to a particle size of more than 80% less than 0.074 mm. A slurry was prepared by mixing water and the polymetallic nodule ore at a mass ratio of 3:1. The slurry was then transferred to a tubular reactor and preheated to 250°C. Sulfuric acid was then pumped into the reactor at a mass ratio of 0.45:1. After reacting for 10 minutes, flash evaporation was performed to separate the solid and liquid components, resulting in a leachate rich in nickel, cobalt, and copper, and a high-pressure acid leaching residue rich in manganese and iron. Samples were prepared and analyzed.

[0046] In this method, the leaching rates of nickel, cobalt, copper, iron and manganese were 96.70%, 92.55%, 95.36%, 8.20% and 12.53%, respectively. Compared with the stepwise high-temperature and high-pressure acid leaching in Example 1, the manganese leaching rate increased.

[0047] Comparative Example 2 The difference from Example 1 is that flash concentration is not performed, and the high-temperature and high-pressure acid leaching slurry is directly subjected to subsequent steps such as solid-liquid separation.

[0048] A polymetallic nodule ore from the seabed, containing 1.05% nickel, 0.20% cobalt, 0.86% copper, 7.18% iron, and 24.64% manganese, is crushed and finely ground until over 80% of the particles are less than 0.074 mm. A slurry is prepared by mixing water and deep-sea nickel-cobalt-manganese polymetallic ore at a mass ratio of 3:1. The slurry is preheated to 95°C. Then, sulfuric acid and the slurry are transferred to a tubular reactor (a continuous reactor with an aspect ratio ≥500 and a slurry flow rate of 1.2 m / s) at a mass ratio of 0.45:1. In the process of increasing the temperature stepwise to 250°C for 10 minutes and the pressure being 4.0 MPa, the high-temperature and high-pressure acid leaching slurry was then cooled to 100°C via a pipeline ice-water bath with zero evaporation. Solid-liquid separation was then performed to obtain a leachate rich in nickel, cobalt, and copper, and a high-pressure acid leaching residue (leaching residue) rich in manganese and iron. The sulfuric acid concentration in the leachate was 50 g / L, and the concentrations of nickel, cobalt, copper, and manganese were 3.41 g / L, 0.62 g / L, 2.75 g / L, and 1.11 g / L, respectively. Compared with Example 1, the concentration of the leachate was reduced.

[0049] Comparative Example 3 The difference from Example 1 is that no calcium and magnesium additives are added during the harmless treatment.

[0050] That is, the non-magnetic tailings are dehydrated to a moisture content of 10%, mixed with calcium and magnesium additives, and pressed into 30mm slag blanks. Then, the slag blanks are solidified and reacted at 120℃ for 1 hour to obtain tailings pellets. The compressive strength of the pellets is measured to be 500N and the softening coefficient is 0.25. These pellets cannot meet the requirements for discharge into the deep seabed at a depth of more than 1000 meters and for storage in pellet form on the seabed.

[0051] analyze: The above experiments show that using a pipeline reactor for high-temperature and high-pressure acid leaching of nickel-cobalt-manganese polymetallic ores can significantly shorten the leaching reaction time without the need for mechanical stirring. Through stepwise high-temperature and high-pressure acid leaching, high leaching rates of nickel, cobalt, and copper can be achieved while reducing manganese leaching and improving the selectivity of nickel, cobalt, and copper acid leaching. The high-temperature and high-pressure acid leaching slurry can be concentrated through three-stage flash evaporation to obtain a leachate with a higher concentration of metal ions and improve sulfuric acid utilization. Furthermore, the addition of calcium and magnesium additives can combine with the active silica in the high-pressure acid leaching residue to form calcium magnesium silicates with a gelling and solidifying effect, thereby solidifying the leaching residue.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0053] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores, characterized in that, include: Deep-sea nickel-cobalt-manganese polymetallic ore is crushed, ground, and pulped to obtain raw ore pulp; The raw ore slurry is mixed with sulfuric acid to obtain a mixture, and the mixture is subjected to high-pressure acid leaching with progressively increasing temperature to obtain a high-temperature and high-pressure acid leaching slurry. The high-temperature and high-pressure acid leaching slurry is subjected to flash concentration with progressively decreasing pressure to obtain a concentrated slurry; The concentrated slurry is subjected to solid-liquid separation to obtain leachate and leaching residue. Nickel, cobalt and manganese in the leachate are precipitated and separated into solid and liquid components to obtain nickel-cobalt-copper enrichment and precipitated liquid.

2. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The deep-sea nickel-cobalt-manganese polymetallic deposit includes seafloor polymetallic nodules and / or seafloor cobalt-rich iron-manganese crusts; (2) The deep-sea nickel-cobalt-manganese polymetallic ore contains 15% to 30% manganese by mass, 0.3% to 1.5% nickel by mass, 0.15% to 1% cobalt by mass, 0.15% to 1.5% copper by mass, and 5% to 20% iron by mass. (3) More than 70% of the raw ore slurry has a particle size of less than 0.074 mm.

3. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The mass of the sulfuric acid is 0.25-0.55 times the mass of the deep-sea nickel-cobalt-manganese polymetallic ore; (2) The high-pressure acid leaching temperature is 150-280℃, the pressure is 0.4-6.5Mpa, and the time is 5-60 minutes.

4. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 3, characterized in that, The high-pressure acid leaching temperature is 230-280℃, the pressure is 2.5-6.5 MPa, and the time is 5-30 minutes.

5. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, High-pressure acid leaching is carried out in a tubular reactor; The tubular reactor includes a continuous reactor with a length-to-diameter ratio ≥ 500; The slurry flow rate in the tubular reactor is 1-3 m / s.

6. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, The flash concentration includes concentrating the high-temperature and high-pressure acid leaching slurry through three or more flash stages and cooling it to 100°C.

7. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, The leaching residue is subjected to magnetic separation to obtain magnetic and non-magnetic products. The non-magnetic products are then treated to render them harmless before being discharged into the seabed. The harmless treatment includes: dehydrating the non-magnetic product to obtain dehydrated leaching residue, mixing the dehydrated leaching residue with calcium and magnesium additives, grinding and rolling to obtain slag blanks. The slag blank is subjected to activation and solidification treatment to obtain tailings pellets.

8. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 7, characterized in that, At least one of the following conditions must be met: (1) The water content of the dehydrated leachate is 10-20%; (2) The rubbing time is 1-30 min; (3) The calcium and magnesium additives include one or more of calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, calcium chloride, and magnesium chloride; (4) The mass of the calcium and magnesium additive is 2-10% of the mass of the dehydrated leaching residue; (5) The particle size of the slag blank is 10-50 mm; (6) The pressure of the roller pressing is 10-40 MPa; (7) The temperature for the activation and curing treatment is 25-200℃, and the time is 0.5-2h; (8) The compressive strength of the tailings pellets is ≥1000N and the softening coefficient is ≥0.85; (9) The depth of the seabed is greater than or equal to 1000 meters.

9. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The total mass content of nickel, cobalt and copper in the nickel-cobalt-copper enrichment is ≥30%; (2) The precipitated liquid is returned to the pulping process; (3) The precipitate includes chemical precipitation and / or electrochemical precipitation.

10. The method for offshore smelting and processing of deep-sea nickel-cobalt-manganese polymetallic ores according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The leachate and the ground deep-sea nickel-cobalt-manganese polymetallic ore are mixed, pre-leached under normal pressure, and separated into solid and liquid to obtain a leachate under normal pressure and a pre-leached residue. The pre-leached residue is then pulped. The atmospheric pressure leachate undergoes the precipitation process; The acid concentration in the atmospheric pressure leachate is ≤15g / L; The temperature for the atmospheric pressure pre-impregnation is 50-100℃, and the time is 5-30 minutes; (2) The raw ore slurry is preheated to obtain a preheated slurry; The flash vapor obtained from flash concentration is returned to the preheating process.

Images