A method for microwave treatment of manganese nodules

Abstract

The present invention belongs to the technical field of deep-sea manganese nodule treatment, and particularly relates to a method for treating manganese nodules by microwave. The following defects exist in the prior art when treating manganese nodules: additional reducing agents need to be added, there are a large number of by-product gases that pollute the environment in the products, the reaction rate is low, the treatment time is long, the energy consumption is high and the pollution is large, and the separation efficiency of gangue components in minerals is low. In view of the above problems, the present invention provides a method for treating manganese nodules by microwave, which includes the following steps: microwave preheating and activation, grinding and premixing, microwave reduction and acid leaching, sulfide precipitation, microwave sulfide smelting, oxygen-enriched blowing, microwave roasting and oxygen pressure leaching, multi-stage extraction. After microwave treatment, the structure of manganese-containing aggregates in the raw ore is destroyed, and the gas-phase components in the raw ore overflow, greatly improving the leaching rate and recovery rate of valuable metals.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep-sea manganese nodule treatment, and particularly relates to a method for treating manganese nodules by microwave. Background Art

[0002] Deep-sea manganese nodules, also known as deep-sea polymetallic nodules, smelting is an important link in the development and utilization of deep-sea polymetallic nodule resources. So far, more than 30 methods for treating polymetallic nodules have been proposed at home and abroad. The number of methods and the breadth of ideas are beyond any terrestrial ore. Moreover, new treatment methods are still being explored. According to literature reports, the current treatment methods for polymetallic nodules can be roughly divided into two categories: the combined pyro-hydrometallurgical process and the all-wet process.

[0003] The following methods are more widely used (the "valuable metals" mentioned below specifically refer to the recoverable metals such as Mn, Fe, Cu, Co, Ni, etc. in deep-sea manganese nodules):

[0004] Reduction smelting - leaching process: The basic principle of smelting an alloy with polymetallic nodules as the raw material is to utilize the difference in properties that Mn is difficult to be reduced to metal (its oxide has a higher free energy), while oxides of Fe, Ni, Co, Cu, etc. are relatively easy to be reduced to metal. At high temperature, Ni, Co, Cu, and Fe in the valuable metals are selectively reduced, and Mn is reduced from the high-valent oxide to MnO and enters the slag phase. The reduction smelting yields a high-iron alloy enriched with main metals and manganese-rich slag. Various metals are recovered and separated from the alloy phase by hydrometallurgical methods, and the manganese-rich slag is further reduced while it is hot to prepare ferrosilicon manganese alloy.

[0005] Reduction smelting - sulfidation - leaching process: First, the dried manganese nodules are selectively reduced and smelted with a carbonaceous reducing agent at a temperature of about 1420°C to produce manganese-rich slag and a Cu-Ni-Co-Fe alloy; then the Cu-Ni-Co-Fe alloy is roasted and oxidized to remove most of the Fe and residual Mn, and then sulfiding agents such as pyrite and gypsum are added to convert Cu, Co, Ni, and residual Fe in the alloy into sulfides to form matte; then the matte is oxidized and blown at a temperature of about 1350°C to remove the iron in it to obtain high-grade matte; finally, the obtained high-grade matte is ground and slurried and then subjected to oxygen pressure leaching with sulfuric acid as the leaching agent to obtain Cu, Co, Ni solutions, and products such as Cu, Ni, and Co in the valuable metals are recovered by solvent extraction, electrowinning, and precipitation methods; while the manganese-rich slag is reduced and smelted with lime at a temperature of 1600°C to produce qualified manganese-based alloy.

[0006] Roasting - leaching process: According to the chemical composition and mineral characteristics of polymetallic nodules, the polymetallic nodules are subjected to roasting pretreatment to change the mineral structure and make it easier to process, and then a hydrometallurgical process is used to recover valuable metals. The roasting methods include chlorination roasting, sulfation roasting, reduction roasting, etc., and the leaching methods include acid leaching, ammonia leaching, water leaching, etc.

[0007] The above - mentioned existing technologies mainly make Mn enter the slag phase by pyro - roasting / smelting first, while strategic metals such as Fe, Co, Cu, Ni enter the alloy phase or matte phase, and then the above - mentioned strategic metals are separated by hydrometallurgy, or simply directly prepared into alloys. No matter which method, its essence is to separate Mn from strategic metals such as Fe, Co, Cu, Ni.

[0008] The disadvantages of the above - mentioned methods are as follows: (1) The pyro - roasting / smelting step requires the addition of extra reducing agents such as carbon powder, coke, pulverized coal, etc. There are a large number of by - product gases polluting the environment such as carbon dioxide, dioxin, carbon sulfide in the products, and at the same time, the treatment cost is increased; the reaction rate is low and the heating time is long; the energy consumption and pollution are high in the processes of grinding, sorting, carbon doping, smelting / roasting, product grinding and sorting, etc., the operation equipment is large, the construction cost is high, and the process is complex; (2) The rate of the wet - leaching step is low and the leaching time is long; a large amount of acid is used, and waste acid is easily generated; the formed alloy has high hardness and high melting point, and the subsequent treatment is difficult; the separation efficiency of gangue components in minerals is low. Summary of the Invention

[0009] Aiming at the problems existing in the prior art, the present invention provides a method for microwave treatment of manganese nodules. The main components of the deep - sea manganese nodules used include MnO2 (25% - 40%), SiO2 (14% - 20%), Fe2O3 (5% - 10%), Al2O3 (3% - 6%), MgO (1% - 5%), CaO (1% - 5%), Na2O (1% - 3%), NiO (1% - 3%), CuO (1% - 3%), Co2O3 (0.1% - 0.3%), etc. The method includes the following steps:

[0010] (1) Microwave pre - heating activation: The manganese nodule raw ore is subjected to microwave pre - heating activation treatment. The structure of the manganese - containing aggregates in the raw ore is destroyed, and the gas - phase components in the raw ore overflow to obtain activated manganese nodules.

[0011] The specific method for microwave preheating activation is as follows: Use microwave heating with a power of 300W - 500W and a frequency of 2.3GHz - 2.8GHz to heat the raw ore to a temperature of 300°C - 500°C. Then, while keeping the microwave frequency unchanged, adjust the microwave power and keep it at this temperature for 20min - 30min. This will destroy the structure of the manganese-containing aggregates in the raw ore, and gaseous components such as SO2 and Cl2 will overflow in situ, making the structure of the raw ore become loose, generating a large number of voids and holes, and the valuable metal elements will be deconstructed to obtain activated manganese nodules.

[0012] (2) Grinding and premixing: Grind the activated manganese nodules prepared in step (1) to obtain activated manganese nodule ore powder. Add high-grade matte as a reducing agent to this activated manganese nodule ore powder and mix well to obtain premixed activated ore powder;

[0013] For every 100g of activated manganese nodule ore powder, 30g - 100g of high-grade matte is added correspondingly.

[0014] (3) Microwave reduction and acid leaching: In a microwave environment, add leaching agent sulfuric acid and high-grade matte as a reducing agent to the premixed activated ore powder obtained in step (2) to form a leaching system for reduction activation leaching, obtaining a microwave acid leaching solution containing ions such as Mn, Co, Ni, Cu, Fe and impurities, as well as an iron-containing acid leaching residue;

[0015] In the reduction activation leaching, the MnO2 and Co2O3 mineral phases in the ore powder are reduced and dissociated, and reconstituted into soluble MnSO4 and CoSO4. At the same time, minerals such as CuO and NiO released are leached by sulfuric acid and converted into copper sulfate and nickel sulfate.

[0016] The microwave environment is to use microwave heating with a power of 100W - 200W and a frequency of 2.3GHz - 2.8GHz to heat the reduction activation leaching system to a temperature of 60°C - 100°C. Then, while keeping the microwave frequency unchanged, adjust the microwave power and keep it at this temperature for 30min - 60min for reduction activation leaching.

[0017] For every 100g of premixed activated ore powder, 30g - 100g of high-grade matte is added correspondingly;

[0018] For every 1g of premixed activated ore powder, 7mL - 10mL of sulfuric acid is added, and the concentration of sulfuric acid is 0.6mol / L - 1.6mol / L.

[0019] The grade of the high-grade matte described in steps (2) and (3) is 60% - 75%, and the main components are as follows: Cu 60% - 70%, S 20% - 25%, Fe 5% - 20%; the sum of the above main components is less than 100%;

[0020] This high-grade matte comes from the copper-smelting matte raw material purchased in advance or is produced by the oxygen-enriched blowing in step (6).

[0021] The microwave acid leaching solution also contains impurities, which include, in addition to the compounds containing elements such as Mn, Co, Ni, Cu, and Fe that are not completely leached from the premixed activated ore powder, compounds containing elements such as Si, Al, Mg, Ca, and Na. In this step, the recovery of all valuable metals (Mn, Co, Ni, Cu, Fe) and the preliminary separation of Fe are achieved (a small amount of Fe is dissolved in the microwave acid leaching solution, and most of the Fe remains in the acid leaching residue). The Fe-containing acid leaching residue can be further used to extract the valuable metals (Mn, Co, Ni, Cu, Fe) that are not completely leached, or used as cement aggregate or other building materials.

[0022] (4) Sulfide precipitation: Add a sulfide precipitant to the microwave acid leaching solution obtained in step (3) to form a sulfide system. Fe, Co, Cu, Ni ions and a small amount of Mn ions in the sulfide system form sulfide precipitates such as cobalt sulfide, copper sulfide, and nickel sulfide, obtaining a manganese sulfide removal residue containing sulfide precipitates and impurities and a manganese-rich sulfide solution containing a large amount of Mn ions, achieving the separation of manganese ions.

[0023] The manganese-rich sulfide solution is distilled to obtain manganese sulfate crystal products; the impurities in the microwave acid leaching solution also precipitate into the manganese sulfide removal residue and become the impurities in the manganese sulfide removal residue.

[0024] The sulfide precipitant includes one or more of Na2S, NaHS, and Na2SO3;

[0025] Use a pH regulator to adjust the pH of the sulfide system to 2 - 5; the pH regulator includes at least one of NaOH, NH3·H2O, NH4Cl, citric acid, etc.;

[0026] For every 1000 mL of microwave acid leaching solution, 30 g - 80 g of sulfide precipitant is added, and the sulfide precipitation time is 30 min - 60 min.

[0027] (5) Microwave sulfide smelting: Add a reducing agent and a sulfiding agent to the manganese sulfide removal residue obtained in step (4) in a microwave environment to form a smelting system for smelting, obtaining low-grade matte and sulfide smelting slag;

[0028] Among them, the low-grade matte (matte grade 40% - 50%) is mainly formed by the sulfidation of copper, nickel, cobalt, a small amount of Mn, and a small part of iron in the manganese sulfide removal residue, achieving the enrichment of copper, nickel, and cobalt; the sulfide smelting slag is mainly formed by most of the iron and impurities in the manganese sulfide removal residue entering the slag phase.

[0029] The microwave environment is to use microwaves with a power of 900 W - 1300 W and a frequency of 2.3 GHz - 2.8 GHz to heat the smelting system to a temperature of 1100 °C - 1300 °C. After reaching the smelting temperature, keep the microwave frequency unchanged and adjust the microwave power to keep the smelting system at this temperature for 60 min - 120 min for smelting.

[0030] The mass of the mixture of the reducing agent and the sulfurizing agent added to every 100 g of the manganese sulfide removal slag is 130 g to 200 g; among which, the mass of the reducing agent is 68 g to 120 g;

[0031] The reducing agent is carbon powder, and the sulfurizing agent is CaSO4;

[0032] (6) Oxygen-enriched blowing: Use an oxygen lance to conduct one-stage blowing on the low-grade matte and the sulfurized smelting slag obtained in step (5). After separating the one-stage blowing slag, continue with two-stage blowing. After separating the two-stage blowing slag, high-grade matte is obtained.

[0033] The oxygen pressure for the one-stage blowing is 200 kPa to 250 kPa, the oxygen enrichment concentration is 50% to 60%, and the one-stage blowing time is 60 min to 120 min; the purpose of the one-stage blowing is to remove iron and a part of sulfur in the low-grade matte to obtain high-grade matte containing 50% to 60% of copper, nickel, and cobalt. Generally, the blowing time for the low-grade matte is long;

[0034] The oxygen pressure for the two-stage blowing is 150 kPa to 200 kPa, the oxygen enrichment concentration is 40% to 50%, and the two-stage blowing time is 30 min to 60 min. When the matte phase grade reaches 60% to 75%, it is considered that the blowing end point is reached.

[0035] The one-stage blowing slag is waste slag and can be used for iron recovery; the two-stage blowing slag is returned to step (5) for microwave sulfurization smelting for recycling. The high-grade matte can be added to step (2) grinding premixing and step (3) microwave reduction acid leaching for use as a reducing agent.

[0036] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to conduct roasting desulfurization treatment on the high-grade matte obtained in step (6) to obtain a roasting product; conduct oxygen pressure leaching on the roasting product in a microwave environment. After the leaching is completed, solid-liquid separation is carried out to obtain an oxygen pressure leaching solution and an oxygen pressure leaching residue.

[0037] The microwave power for the roasting desulfurization is 500 W to 800 W, the frequency is 2.3 GHz to 2.8 GHz. Use microwave heating to make the temperature of the high-grade matte be 500 °C to 800 °C. Keep the microwave frequency unchanged and adjust the microwave power to make the high-grade matte roast at this temperature for 30 min to 120 min;

[0038] During the oxygen pressure leaching, first use microwave heating with a power of 100 W to 200 W and a frequency of 2.3 GHz to 2.8 GHz to make the temperature of the oxygen pressure leaching system be 160 °C to 200 °C. After reaching the target temperature, keep the microwave frequency unchanged and adjust the microwave power to make the leaching system carry out heat preservation leaching at this temperature for 60 min to 150 min, and the pure oxygen oxygen pressure is 100 kPa to 700 kPa.

[0039] Sulfuric acid is used as the leaching solution, with a sulfuric acid concentration of 0.6 mol / L to 1.6 mol / L, and 7 mL to 10 mL of leaching solution is used per 1 g of roasted product;

[0040] The SO2 generated by roasting is absorbed by NaOH, and the obtained Na2SO3 can be recycled as a sulfide precipitant in step (4); the oxygen pressure leaching residue can be deeply purified to separate metals such as Mn, Co, Ni, Cu, and Fe, and can also be used as cement aggregate and building materials.

[0041] (8)Multi-stage extraction: After the oxygen pressure leaching solution obtained in step (7) is extracted, manganese, copper, nickel, and cobalt are separated;

[0042] The extraction method is as follows: First, P204 is used to extract manganese from the leaching solution to obtain a manganese-containing extract and a manganese-removed raffinate. Then, Lix984 is used to extract copper from the manganese-removed raffinate to obtain a copper-containing extract and a copper-removed raffinate. Next, Cyanex272 is used to extract cobalt from the copper-removed raffinate to obtain a cobalt-containing extract and a cobalt-removed raffinate. Finally, P507 is used to extract nickel from the cobalt-removed raffinate to obtain a nickel-containing extract and a nickel-removed raffinate;

[0043] The above-mentioned extracts are all organic phases, and the raffinates are all aqueous phases. It is necessary to perform back-extraction to return the extractants in the extracts to the aqueous phase. The regenerated organic phase containing no or a small amount of extractants obtained after back-extraction is returned to the corresponding extraction process for continued use.

[0044] The concentration of the extractant is 10% to 30% (sulfonated kerosene is used as the diluent), the extraction phase ratio is 0.5 to 2.5, the mixing time is 5 min to 15 min, the phase separation time is 5 min to 15 min, and the number of extraction stages is 3 to 9; the back-extraction uses an aqueous solution of conventional inorganic chemical reagents such as H2SO4 or NaOH; through multiple multi-stage extraction and back-extraction processes, the efficient separation of Mn, Cu, Co, and Ni is achieved.

[0045] Explanation of the microwave preheating activation effect in step (1): Cobalt, nickel, and copper in polymetallic nodules are mainly distributed in the crystal lattice of iron and manganese oxide minerals in the form of isomorphic substitution. The results of process mineralogy research show that manganese in the minerals mainly exists in the form of Mn 4+ oxide, that is, MnO2. MnO2 is very stable under conventional conditions and cannot be directly destroyed by sulfuric acid, which leads to a very slow leaching rate and low recovery rate of valuable metals. The key to improving the leaching efficiency of valuable metals lies in destroying the mineral structure of the nodules, especially the destruction of the manganese mineral structure. Through microwave activation, the mineral phase of manganese oxide minerals in the raw ore dissociates and reconstructs. The oxides of cobalt, nickel, copper, etc. bound to the manganese oxide mineral matrix will be exposed or freed during the dissociation and reconstruction process, playing a role in component activation, reducing the activation energy of the leaching reaction of cobalt, nickel, and copper, and being conducive to improving the subsequent leaching effect.

[0046] In step (4) of sulfide precipitation, according to the sulfide precipitation equilibrium of common metal ions, the solubility products of CoS, CuS, NiS, and MnS differ greatly. The sulfide precipitation method can be used to precipitate cobalt, nickel, and copper from the microwave acid leaching solution containing Co 2+ , Cu 2+ , Ni 2+ , Mn 2+ , so that cobalt, nickel, copper, and manganese can be well separated. During the sulfide precipitation process, Fe 2+ in the microwave acid leaching solution will simultaneously undergo sulfide precipitation transformation and enter the manganese sulfide removal slag together with Co 2+ , Cu 2+ , Ni 2+ , realizing the deep purification of the manganese-rich sulfide solution.

[0047] The microwave acid leaching solution is acidic. During the sulfide precipitation process, S 2- in the sulfide system will decompose according to the following formula:

[0048] S 2- + H2O ⇋ HS - + OH - (1)

[0049] HS - + H2O ⇋ H2S + OH - (2)

[0050] SO3 2- + H2O ⇋ HSO3 - + OH - (3)

[0051] Increasing the solution pH (increasing [OH - ) can reduce the decomposition degree of S 2- and SO3 2- . The sulfide precipitant forms an S 2- -HS - and SO3 2- - HSO3 - buffer system in the sulfide system. Combining with a pH regulator, the pH of the sulfide system is controlled at 2 - 5 to reduce the decomposition consumption of S 2- and SO3 2- , thereby improving the utilization rate of the sulfide agent. Therefore, in a complex sulfide system containing Mn 2+ , Fe 2+ , Co 2+ , Cu 2+ , Ni 2+ and other ions, the key to achieving selective sulfide precipitation is to regulate the solution pH, establish a more appropriate buffer system, ensure the deep precipitation of target metal ions, and improve the utilization rate of the sulfide agent while reducing the process cost.

[0052] In step (5), during microwave sulfide smelting, carbon powder C and calcium sulfate CaSO4 are used as reducing agents and sulfiding agents. CaSO4 decomposes into CaS under the action of C. CaS reacts with metal oxides MeO (CuO, NiO, CoO, a small amount of FeO) formed during the sulfide smelting process to produce metal sulfides MeS (Me refers to Cu, Co, Ni, Fe) and CaO; CaO reacts with impurities in the sulfide de-manganese slag to form a slag, and together with the remaining Fe, a sulfide smelting slag is formed.

[0053] CaSO4 + C → CaS + CO2 (4)

[0054] MeO + CaS → MeS + CaO (5)

[0055] The process of sulfide conversion of metal oxides may be as follows:

[0056] CuO → Cu → Cu2S (6)

[0057] NiO → Ni → Ni3S2 (7)

[0058] CoO → Co → Co9S8 (8)

[0059] FeO → Fe → FeS (9)

[0060] In step (6), during oxygen-enriched blowing, the order of the affinity of metals for oxygen is Fe > Co > Ni > Cu. Blowing is carried out under a certain oxygen potential condition, and FeS in the low-grade matte will be preferentially oxidized to form slag. The basic reaction for iron removal by blowing is:

[0061] FeS + O2 → FeO + SO2 (10)

[0062] FeO + SiO2 → FeO·SiO2 (11)

[0063] Different from the traditional method of obtaining metals by blowing matte, in the present invention, for the oxidation blowing of low-grade matte containing copper, nickel and cobalt, only iron removal by blowing is carried out, and after obtaining high-grade matte containing copper, nickel and cobalt, oxygen pressure leaching is carried out.

[0064] As blowing progresses, most of the iron is removed by slag formation, and the grade of the matte continuously increases and turns into high-grade matte. When blowing reaches a certain degree, further blowing will cause the oxidation and slag formation reactions of cobalt, nickel and copper, resulting in the loss of valuable metals. To reduce the loss of valuable metals in the later stage of blowing, we plan to adopt a two-stage blowing method to blow the low-grade matte. The slag from the first-stage blowing (iron precipitation slag) meets the waste slag standard, and the slag from the second-stage blowing is returned to sulfide smelting.

[0065] In step (7), during microwave roasting oxygen pressure leaching, if high-grade matte is subjected to low-temperature oxygen pressure leaching, that is, at a reaction temperature of 100°C to 140°C and in the presence of sufficient oxygen, the metal sulfide reacts with oxygen and sulfuric acid to form metal sulfate and elemental sulfur:

[0066] MeS + O2 + H2SO4 → MeSO4 + H2O + S (12)

[0067] Meanwhile, the following reactions occur:

[0068] MeS + H2SO4 → MeSO4 + H2S (Me = Mn, Fe, Cu, Co, Ni) (13)

[0069] H2S + O2 → H2O + S (14)

[0070] FeSO4 + O2 + H2SO4 → Fe2(SO4)3 + H2O (15)

[0071] H2S + Fe2(SO4)3 → FeSO4 + H2SO4 + S (16)

[0072] MeS + Fe2(SO4)3 → FeSO4 + MeSO4 + S (17)

[0073] Fe2(SO4)3 + H2O → Fe2O3 + H2SO4 (18)

[0074] Fe2(SO4)3 + H2O + Na2SO4 → Na2Fe6(SO4)4(OH) 12 + H2SO4 (19)

[0075] At this temperature, the hydrolysis product of iron is not mainly hematite, but the precipitation reaction of jarosite (reaction formula 19) is more dominant. In order to achieve an ideal iron removal effect, a monovalent cation is added inside or outside the autoclave, and effective iron removal can be achieved. The monovalent cation can be provided by the raffinate of the subsequent extraction process. The elemental sulfur and iron hydrolysis slag generated by the reaction enter the leaching residue together and return to sulfide smelting, where they can be used as sulfiding agent and slag-forming agent respectively.

[0076] Temperature has a great influence on the reaction process and results of metal sulfide oxygen pressure leaching. At a lower temperature (100°C to 140°C), sulfur in the metal sulfide is oxidized to elemental sulfur, as shown in reaction formula (12).

[0077] The above is the basic principle of removing iron by hydrothermal method of hydrometallurgy.

[0078] The elemental sulfur produced by low-temperature oxygen pressure leaching will form a sulfur film on the surface of the mineral, hindering the progress of the leaching reaction. Moreover, low temperature is not conducive to the hematite precipitation reaction, and the iron removal effect is poor. Increasing the reaction temperature can effectively avoid these problems. Therefore, we choose high-temperature oxygen pressure leaching.

[0079] In the present invention, when the temperature is relatively high (>160 °C), metal sulfides are directly oxidized to sulfates:

[0080] MeS + O2 → MeSO4 (20)

[0081] Among them, FeSO4 will further undergo oxidative hydrolysis under high temperature and sufficient oxygen:

[0082] FeSO4 + O2 + H2O → Fe2O3 + H2SO4 (21)

[0083] After the high-grade matte of the present invention is subjected to microwave roasting, the metal sulfides therein undergo roasting desulfurization, and the generated SO2 escapes, reducing the sulfur content in the system when entering the autoclave for oxygen pressure leaching, and further reducing the sulfuric acid concentration in the system at the end of oxygen pressure leaching. While enabling the efficient leaching of copper, nickel, and cobalt, it creates favorable conditions for the formation of hematite (Fe2O3), achieving efficient iron removal.

[0084] The beneficial effects of the present invention are as follows:

[0085] 1. This design proposes a method of using microwave treatment to allow sulfur dioxide and other gases in the mineral to escape, generating some microcracks inside the manganese nodules, creating a macroscopic phase interface, resulting in a loose macroscopic structure and mineral phase changes. This pretreatment method is beneficial for subsequent grinding and leaching. That is, it first changes the macroscopic structure of the ore, making more defects (microcracks) appear inside the ore. The grinding resistance is small, the difficulty is low, and the obtained ore powder is finer. It makes more reactive positions appear inside the ore, which is beneficial for the subsequent reactions, leaching, separation, etc. of valuable metals and media. Compared with conventional heating, microwave heating not only has the characteristic of rapid heating but also can increase the reaction rate of the reduction process. It can perform pretreatment on the ore without adding reducing agents and without crushing the original ore, that is, without forming alloys, allowing the in-situ gas components in the ore phase to diffuse along the pores, cracks, and phase interfaces in the original ore, making the structure of the original ore loose and facilitating subsequent processing.

[0086] 2. Microwaves can enhance the leaching of manganese, and achieve efficient leaching of copper, nickel and cobalt on the basis of efficient dissociation and reconstruction of the mineral phase structure of polymetallic nodules. At the same leaching amount, the amount of ore can be reduced by 25% and the amount of acid / alkali can be reduced by more than 10%. Under the same amount of ore and acid / alkali, the recovery rate of manganese under microwave heating is increased by more than 19% compared with conventional heating. The electromagnetic radiation of microwaves intensifies the turbulent flow of the solution to a certain extent, and accelerates the process of redox reaction to a certain extent.

[0087] 3. More sulfides will be produced during the sulfidation roasting process, and more S and MnS will appear under the conventional heating system. The further oxidation reaction of sulfur element is difficult to proceed under the conventional heating system, and the hydrophobicity of sulfur element and low-valent sulfides affects the reduction reaction. Microwave heating can effectively alleviate the formation of sulfur element, promote the redox reaction of low-valent sulfur, and thus greatly improve the manganese leaching efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 The present invention is a schematic diagram of the process of using microwaves to treat manganese nodules. DETAILED DESCRIPTION

[0089] The technical scheme of the present invention is clearly and completely described below in conjunction with the embodiments and the accompanying drawings. It should be pointed out that the embodiments described in the present invention are only used to further explain and illustrate, rather than to limit the scope of application. Based on the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the protection scope of the present invention.

[0090] In the embodiment, steps (2) and (3) initially use commercially available high-grade matte, i.e., pre-purchased copper smelting matte raw material, which has a grade of 73% and main components of 60% Cu, 13% Fe, and 25% S. After continuous production, the high-grade matte obtained by the second-stage blowing in step (6) can be used to replace the commercially available matte for steps (2) and (3).

[0091] The process of microwave treatment of manganese nodules in the present invention is as follows: Figure 1 shown.

[0092] The microwave processing equipment used in the present invention is a Kejing experimental microwave box furnace KSL-1400W-MW.

[0093] Example 1

[0094] The main components of the deep-sea manganese nodules in this embodiment include MnO2 (25.9%), SiO2 (16.3%), Fe2O3 (7.6%), Al2O3 (4.3%), MgO (3.7%), CaO (4.5%), Na2O (1.2%), NiO (1.1%), CuO (1.1%), and Co2O3 (0.19%).

[0095] 1. Microwave preheating activation: Take 100 g of the original deep-sea manganese nodule ore and perform microwave preheating activation. The microwave power is 300 W, the frequency is 2.3 GHz. Use microwave heating to raise the temperature of the original ore to 300 °C. Keep the microwave frequency unchanged and adjust the microwave power to keep the original ore at 300 °C for heat preservation treatment for 30 min to obtain activated manganese nodules;

[0096] 2. Grinding and premixing: Grind the activated manganese nodules to obtain ore powder of about 0.8 mm. Take 100 g of the deep-sea manganese nodule ore powder and mix it with 30 g of the high-grade matte as a reducing agent to obtain premixed activated ore powder;

[0097] 3. Microwave reduction and acid leaching: In a microwave environment, add the leaching agent sulfuric acid and the high-grade matte as a reducing agent to the premixed activated ore powder for reduction activation leaching. The microwave power is 100 W, the frequency is 2.3 GHz. Use microwave heating to raise the temperature of the leaching system to 60 °C, then keep the microwave frequency unchanged and adjust the microwave power, and carry out heat preservation leaching at this temperature for 30 min; for every 1 g of premixed activated ore powder, it corresponds to 7 mL of acid leaching solution; the sulfuric acid concentration is 0.6 mol / L; obtain a microwave acid leaching solution containing Mn, Co, Ni, Cu, Fe and other ions and an acid leaching residue containing Fe; there are still impurities in this microwave acid leaching solution. In addition to the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, it also includes compounds containing elements such as Si, Al, Mg, Ca, Na, etc.; the Mn recovery rate in the microwave acid leaching solution is 92.5%, the Fe recovery rate is 8.5%, and the recovery rates of other valuable metals Ni, Cu, Co are about 85.5%, 87.6%, 86.9% respectively;

[0098] 4. Sulfide precipitation: Dilute the microwave acid leaching solution with water to a volume of 1000 mL and add 30 g of sodium sulfite Na2SO3 to form a sulfide system; use NaOH as a pH regulator to adjust the pH of the sulfide system to 2. The sulfide reaction time is 30 min to form sulfide precipitates of Fe, Co, Cu, Ni and other ions and a small amount of Mn ions, obtaining a sulfide manganese removal slag containing sulfide precipitates and a manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the sulfide manganese removal slag together and become the impurities in the sulfide manganese removal slag; filter and dry the sulfide manganese removal slag for standby. The recovery rates of Fe, Co, Cu, Ni are about 94.5%, 94.7%, 95.1%, 95.4% respectively;

[0099] (5) Microwave sulfide smelting: In a microwave environment, 68 g of reducing agent carbon powder and 62 g of sulfiding agent CaSO4 are added to the manganese sulfide removal slag to form a smelting system for smelting. The smelting system is rapidly heated to 1100 °C by microwave heating with a power of 900 W and a frequency of 2.45 GHz. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 60 min. Copper, nickel, cobalt, a small amount of Mn, and a small part of iron in the manganese sulfide removal slag are sulfided to form a low-grade matte phase (grade 40%). Most of the iron and impurities in the manganese sulfide removal slag enter the slag phase to form sulfide smelting slag;

[0100] (6) Oxygen-enriched blowing: Use an oxygen lance to conduct primary blowing on the low-grade matte and sulfide smelting slag, with an oxygen pressure of 200 kPa, an oxygen-enriched concentration of 50%, and a blowing time of 60 min. After separating and removing the primary blowing slag, secondary blowing is carried out, with an oxygen pressure of 150 kPa and an oxygen-enriched concentration of 40%. When the matte grade reaches 60%, the secondary blowing ends, and high-grade matte is obtained; The secondary blowing slag is returned to step (5) for microwave sulfide smelting and recycling. The recovery rate of Fe in the primary blowing slag in the oxygen-enriched blowing step is approximately 92.7%;

[0101] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to roast and desulfurize the high-grade matte, with a microwave power of 500 W and a frequency of 2.4 GHz, so that the temperature of the high-grade matte is 500 °C. The microwave power is adjusted while keeping the microwave frequency unchanged, and it is kept at this temperature for 30 min for heat preservation treatment; After the roasting ends, the roasted product is added to a reaction kettle. Under the pressure of pure oxygen with an oxygen pressure of 100 kPa, 7 mL of leaching agent is used per 1 g of roasted product, and 0.6 mol / L sulfuric acid is used as the leaching agent. The oxygen pressure leaching system is rapidly heated to 160 °C by microwave heating with a power of 100 W and a frequency of 2.3 GHz. The microwave power is adjusted while keeping the microwave frequency unchanged, and it is kept at this temperature for 60 min for leaching. After the leaching ends, solid-liquid separation is carried out to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 94.6%, 95.1%, and 94.7% respectively;

[0102] (8)Multi-stage extraction: Add the oxygen pressure leaching solution to a multi-stage extraction device. First, extract manganese with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, extract copper from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, extract cobalt from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, extract nickel from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate; during the extraction process, the concentration of the extractant is 10% (sulfonated kerosene is used as the diluent), the ratio of the extraction phase to the stripping phase is 0.5, the mixing time is 5 min, the phase separation time is 5 min, the number of extraction and stripping stages is 3, and sulfuric acid with a concentration of 6% is used as the stripping agent; the extraction rates of Ni, Co, Cu, and Mn are 97.5%, 98.3%, 97.8%, and 98.5% respectively.

[0103] Example 2

[0104] The main components of the deep-sea manganese nodules in this example include MnO2 (33.6%), SiO2 (14.7%), Fe2O3 (6.7%), Al2O3 (4.5%), MgO (3.4%), CaO (3.5%), Na2O (1.3%), NiO (1.3%), CuO (1.1%), and Co2O3 (0.21%).

[0105] (1)Microwave preheating and activation: Take 100 g of the original deep-sea manganese nodule ore and perform microwave preheating and activation. The microwave power is 350 W and the frequency is 2.4 GHz. Use microwave heating to raise the temperature of the original ore to 350 °C, keep the microwave frequency unchanged and adjust the microwave power to keep the original ore at 350 °C for heat preservation treatment for 28 min to obtain activated manganese nodules;

[0106] (2)Grinding and premixing: Grind the activated manganese nodules to obtain ore powder of about 0.8 mm. Take 100 g of the deep-sea manganese nodule ore powder and mix it with 40 g of the high-grade matte reductant to obtain premixed activated ore powder;

[0107] (3)Microwave reduction acid leaching: In a microwave environment, leaching agent sulfuric acid and reducing agent high-grade matte are added to the premixed activated ore powder for reduction activation leaching. The microwave power is 120 W and the frequency is 2.35 GHz. After the temperature of the leaching system reaches 70 °C by microwave heating, the microwave power is adjusted while keeping the microwave frequency unchanged. The leaching is carried out at this temperature for 40 min; for every 1 g of premixed activated ore powder, there are 8 mL of acid leaching solution; the sulfuric acid concentration is 0.8 mol / L; a microwave acid leaching solution containing Mn, Co, Ni, Cu, Fe and other ions and an iron-containing acid leaching residue are obtained; there are still impurities in this microwave acid leaching solution. In addition to the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, the impurities also include compounds containing elements such as Si, Al, Mg, Ca, Na, etc.; the recovery rate of Mn in the microwave acid leaching solution is 93.7%, the recovery rate of Fe is 8.2%, and the recovery rates of other valuable metals Ni, Cu, Co are approximately 86.4%, 88.2%, 87.4% respectively;

[0108] (4)Sulfide precipitation: The microwave acid leaching solution is made up to 1000 mL with water and 38 g of NaHS is added to form a sulfide system; NH3·H2O is used as a pH regulator to adjust the pH of the sulfide system to 2.5. The sulfide reaction time is 40 min to form sulfide precipitates of Fe, Co, Cu, Ni and other ions and a small amount of Mn ions, obtaining a manganese sulfide removal residue containing sulfide precipitates and a manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the manganese sulfide removal residue and become the impurities in the manganese sulfide removal residue; the manganese sulfide removal residue is filtered and dried for standby. The recovery rates of Fe, Co, Cu, Ni are approximately 95.1%, 95.5%, 95.6%, 95.8% respectively;

[0109] (5)Microwave sulfide smelting: In a microwave environment, 72 g of reducing agent carbon powder and 68 g of sulfiding agent CaSO4 are added to the manganese sulfide removal residue to form a smelting system for smelting. The smelting system is rapidly heated to 1200 °C by microwave heating with a power of 1000 W and a frequency of 2.55 GHz. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 70 min, so that copper, nickel, cobalt, a small amount of Mn and a small part of iron in the manganese sulfide removal residue are sulfided to form a low-grade matte phase (grade 43%), and most of the iron and impurities in the manganese sulfide removal residue enter the slag phase to form a sulfide smelting slag;

[0110] (6) Oxygen-enriched blowing: Use an oxygen lance to conduct a one-stage blowing on low-grade matte and sulfide smelting slag, with an oxygen pressure of 210 kPa, an oxygen-enriched concentration of 53%, and a blowing time of 65 minutes. After separating and removing the one-stage blowing slag, conduct a two-stage blowing, with an oxygen pressure of 160 kPa and an oxygen-enriched concentration of 43%. When the matte grade reaches 63%, the two-stage blowing ends, and high-grade matte is obtained; return the two-stage blowing slag to step (5) for microwave sulfide smelting for recycling. The recovery rate of Fe in the one-stage blowing slag in the oxygen-enriched blowing step is approximately 93.3%;

[0111] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to conduct roasting and desulfurization treatment on high-grade matte, with a microwave power of 560 W and a frequency of 2.46 GHz, so that the temperature of the high-grade matte is 550 °C. Keep the microwave frequency unchanged and adjust the microwave power, and conduct heat preservation treatment at this temperature for 40 minutes; after the roasting ends, add the roasting product into a reaction kettle, and under the pressure of pure oxygen with an oxygen pressure of 200 kPa, use 8 mL of leaching agent per 1 g of roasting product, and 0.8 mol / L sulfuric acid as the leaching agent. Use microwave heating with a power of 120 W and a frequency of 2.4 GHz to quickly raise the temperature of the oxygen pressure leaching system to 170 °C. Keep the microwave frequency unchanged and adjust the microwave power, and conduct heat preservation leaching at this temperature for 70 minutes. After the leaching ends, conduct solid-liquid separation to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 95.1%, 95.7%, and 95.4% respectively;

[0112] (8) Multi-stage extraction: Add the oxygen pressure leaching solution into a multi-stage extraction device. First, extract manganese with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, extract copper from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, extract cobalt from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, extract nickel from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate; during the extraction process, the concentration of the extractant is 15% (sulfonated kerosene as the diluent), the ratio of the extraction phase to the stripping phase is 1.0, the mixing time is 8 minutes, the phase separation time is 8 minutes, the number of extraction and stripping stages is 5, and 6% sulfuric acid is used as the stripping agent; the extraction rates of Ni, Co, Cu, and Mn are 98.1%, 98.5%, 98.2%, and 98.8% respectively.

[0113] Example 3

[0114] The main components of the deep-sea manganese nodules in this example include MnO2 (35.5%), SiO2 (15.8%), Fe2O3 (5.7%), Al2O3 (3.5%), MgO (2.2%), CaO (4.5%), Na2O (1.6%), NiO (1.2%), CuO (1.4%), Co2O3 (0.26%).

[0115] (1)Microwave preheating activation: Take 100 g of raw deep-sea manganese nodules and perform microwave preheating activation. The microwave power is 400 W and the frequency is 2.5 GHz. Use microwave heating to raise the temperature of the raw ore to 400 °C. Keep the microwave frequency unchanged and adjust the microwave power to keep the raw ore at 400 °C for heat preservation treatment for 26 min to obtain activated manganese nodules;

[0116] (2)Grinding and premixing: Grind the activated manganese nodules to obtain ore powder of about 0.8 mm. Take 100 g of deep-sea manganese nodule ore powder and mix it with 55 g of high-grade matte as a reducing agent to obtain premixed activated ore powder;

[0117] (3)Microwave reduction and acid leaching: In a microwave environment, add leaching agent sulfuric acid and high-grade matte as a reducing agent to the premixed activated ore powder for reduction activation leaching. The microwave power is 140 W and the frequency is 2.45 GHz. Use microwave heating to raise the temperature of the leaching system to 80 °C, then keep the microwave frequency unchanged and adjust the microwave power to carry out heat preservation leaching at this temperature for 50 min; for every 1 g of premixed activated ore powder, it corresponds to 9 mL of acid leaching solution; the sulfuric acid concentration is 1.0 mol / L; obtain microwave acid leaching solution containing Mn, Co, Ni, Cu, Fe and other ions and acid leaching residue containing Fe; there are still impurities in this microwave acid leaching solution. Besides the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, the impurities also include compounds containing elements such as Si, Al, Mg, Ca, Na, etc.; the recovery rate of Mn in the microwave acid leaching solution is 94.3%, the recovery rate of Fe is 8.0%, and the recovery rates of other valuable metals Ni, Cu, Co are about 86.6%, 88.6%, 87.9% respectively;

[0118] (4)Sulfide precipitation: Dilute the microwave acid leaching solution to 1000 mL with water and add 46 g of Na2S to form a sulfide system; use NH4Cl as a pH regulator to adjust the pH of the sulfide system to 2.9. The sulfide reaction time is 50 min to form sulfide precipitates of Fe, Co, Cu, Ni and other ions and a small amount of Mn ions, obtaining sulfide manganese removal slag containing sulfide precipitates and manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the sulfide manganese removal slag and become the impurities in the sulfide manganese removal slag; filter and dry the sulfide manganese removal slag for standby. The recovery rates of Fe, Co, Cu, Ni are about 95.6%, 96.1%, 96.2%, 96.4% respectively;

[0119] (5) Microwave sulfide smelting: In a microwave environment, 88 g of reducing agent carbon powder and 74 g of sulfiding agent CaSO4 are added to the manganese sulfide removal slag to form a smelting system for smelting. The smelting system is rapidly heated to 1250 °C by microwave heating with a power of 1100 W and a frequency of 2.6 GHz. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 80 min, so that copper, nickel, cobalt, a small amount of Mn and a small part of iron in the manganese sulfide removal slag are sulfided to form a low-grade matte phase (grade 47%). Most of the iron and impurities in the manganese sulfide removal slag enter the slag phase to form sulfide smelting slag;

[0120] (6) Oxygen-enriched blowing: Use an oxygen lance to carry out primary blowing on the low-grade matte and sulfide smelting slag, with an oxygen pressure of 220 kPa and an oxygen-enriched concentration of 55%, and the blowing time is 75 min. After separating and taking out the primary blowing slag, secondary blowing is carried out, with an oxygen pressure of 170 kPa and an oxygen-enriched concentration of 46%. When the matte grade reaches 65%, the secondary blowing ends, and high-grade matte is obtained; The secondary blowing slag is returned to step (5) for microwave sulfide smelting and recycling. The recovery rate of Fe in the primary blowing slag in the oxygen-enriched blowing step is about 93.7%;

[0121] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to carry out roasting and desulfurization treatment on the high-grade matte, with a microwave power of 620 W and a frequency of 2.58 GHz, so that the temperature of the high-grade matte is 600 °C. The microwave power is adjusted while keeping the microwave frequency unchanged, and it is kept at this temperature for 50 min; After roasting, the roasted product is added to the reaction kettle. Under the pressure of pure oxygen with an oxygen pressure of 300 kPa, 9 mL of leaching agent is used for every 1 g of roasted product, and 1.0 mol / L sulfuric acid is used as the leaching agent. The oxygen pressure leaching system is rapidly heated to 180 °C by microwave heating with a power of 140 W and a frequency of 2.5 GHz. The microwave power is adjusted while keeping the microwave frequency unchanged, and it is kept at this temperature for 80 min for leaching. After leaching, solid-liquid separation is carried out to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 95.5%, 96.1%, and 95.8% respectively;

[0122] (8) Multi-stage extraction: Add the oxygen pressure leaching solution to a multi-stage extraction device. First, extract manganese with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, extract copper from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, extract cobalt from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, extract nickel from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate. During the extraction process, the concentration of the extractant is 20% (sulfonated kerosene is used as the diluent), the ratio of the extraction phase to the stripping phase is 1.5, the mixing time is 10 min, the phase separation time is 11 min, the number of extraction and stripping stages is 7, and sulfuric acid with a concentration of 6% is used as the stripping agent. The extraction rates of Ni, Co, Cu, and Mn are 98.4%, 98.7%, 98.4%, and 99.0% respectively.

[0123] Example 4

[0124] The main components of the deep-sea manganese nodules in this example include MnO2 (37.9%), SiO2 (17.3%), Fe2O3 (9.7%), Al2O3 (3.1%), MgO (1.1%), CaO (1.9%), Na2O (1.0%), NiO (1.8%), CuO (1.7%), and Co2O3 (0.12%).

[0125] (1) Microwave preheating activation: Take 100 g of the original deep-sea manganese nodule ore and perform microwave preheating activation. The microwave power is 450 W and the frequency is 2.6 GHz. Use microwave heating to raise the temperature of the original ore to 400 °C. Keep the microwave frequency unchanged and adjust the microwave power to keep the original ore at 400 °C for heat preservation treatment for 26 min to obtain activated manganese nodules.

[0126] (2) Grinding and premixing: Grind the activated manganese nodules to obtain ore powder with a particle size of about 0.8 mm. Take 100 g of the deep-sea manganese nodule ore powder and mix it with 70 g of high-grade matte as the reducing agent to obtain premixed activated ore powder.

[0127] (3)Microwave reduction acid leaching: In a microwave environment, a leaching agent sulfuric acid and a reducing agent high-grade matte are added to the premixed activated ore powder for reduction activation leaching. The microwave power is 160 W and the frequency is 2.6 GHz. After the temperature of the leaching system reaches 90 °C by microwave heating, the microwave power is adjusted while keeping the microwave frequency unchanged. The leaching is carried out at this temperature for 60 min; for every 1 g of premixed activated ore powder, there are 10 mL of acid leaching solution; the sulfuric acid concentration is 1.2 mol / L; a microwave acid leaching solution containing Mn, Co, Ni, Cu, Fe and other ions and an iron-containing acid leaching residue are obtained; there are still impurities in this microwave acid leaching solution. Besides the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, the impurities also include compounds containing Si, Al, Mg, Ca, Na and other elements; the recovery rate of Mn in the microwave acid leaching solution is 94.8%, the recovery rate of Fe is 8.0%, and the recovery rates of other valuable metals Ni, Cu, Co are about 87.2%, 89.1%, 88.4% respectively;

[0128] (4)Sulfide precipitation: The microwave acid leaching solution is made up to 1000 mL with water and 55 g of sodium sulfite Na2SO3 is added to form a sulfide system; NaOH is used as a pH regulator to adjust the pH of the sulfide system to 3.3. The sulfide reaction time is 60 min to form sulfide precipitates of Fe, Co, Cu, Ni and other ions and a small amount of Mn ions, obtaining a manganese sulfide removal residue containing sulfide precipitates and a manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the manganese sulfide removal residue and become the impurities in the manganese sulfide removal residue; the manganese sulfide removal residue is filtered and dried for standby. The recovery rates of Fe, Co, Cu, Ni are about 95.8%, 96.3%, 96.4%, 96.7% respectively;

[0129] (5)Microwave sulfide smelting: In a microwave environment, 97 g of reducing agent carbon powder and 80 g of sulfiding agent CaSO4 are added to the manganese sulfide removal residue to form a smelting system for smelting. The microwave with a power of 1200 W and a frequency of 2.7 GHz is used to heat the smelting system to quickly reach 1265 °C. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 90 min, so that copper, nickel, cobalt, a small amount of Mn and a small part of iron in the manganese sulfide removal residue are sulfided to form a low-grade matte phase (grade 48%), and most of the iron and impurities in the manganese sulfide removal residue enter the slag phase to form a sulfide smelting slag;

[0130] (6) Oxygen-enriched blowing: Use an oxygen lance to conduct a one-stage blowing on low-grade matte and sulfide smelting slag. The oxygen pressure is 240 kPa, the oxygen enrichment concentration is 57%, and the blowing time is 90 min. After separating and removing the one-stage blowing slag, conduct a two-stage blowing. The oxygen pressure is 180 kPa, and the oxygen enrichment concentration is 48%. When the matte grade reaches 67%, the two-stage blowing ends, and high-grade matte is obtained. Return the two-stage blowing slag to step (5) for microwave sulfide smelting and recycling. The recovery rate of Fe in the one-stage blowing slag in the oxygen-enriched blowing step is approximately 94.4%;

[0131] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to conduct roasting and desulfurization treatment on high-grade matte. The microwave power is 700 W, the frequency is 2.7 GHz, and the temperature of the high-grade matte is 700 °C. Keep the microwave frequency unchanged and adjust the microwave power. Conduct heat preservation treatment at this temperature for 70 min. After the roasting ends, add the roasting product into the reaction kettle. Under the pressure of pure oxygen with an oxygen pressure of 400 kPa, for every 1 g of roasting product, use 10 mL of leaching agent, and 1.2 mol / L sulfuric acid is used as the leaching agent. Use microwave heating with a power of 160 W and a frequency of 2.6 GHz to quickly raise the temperature of the oxygen pressure leaching system to 190 °C. Keep the microwave frequency unchanged and adjust the microwave power. Conduct heat preservation leaching at this temperature for 100 min. After the leaching ends, perform solid-liquid separation to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 96.3%, 96.8%, and 96.5% respectively;

[0132] (8) Multistage extraction: Add the oxygen pressure leaching solution to a multistage extraction device. First, use P204 to extract manganese to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, use Lix984 to extract copper from the manganese-removed raffinate to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, use Cyanex272 to extract cobalt from the copper-removed raffinate to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, use P507 to extract nickel from the cobalt-removed raffinate to obtain a nickel-containing extraction solution and a nickel-removed raffinate. During the extraction process, the concentration of the extractant is 25% (sulfonated kerosene is used as the diluent), the ratio of the extraction phase to the stripping phase is 2.0, the mixing time is 12 min, the phase separation time is 13 min, the number of extraction and stripping stages is 9, and 6% sulfuric acid is used as the stripping agent. The extraction rates of Ni, Co, Cu, and Mn are 98.7%, 99.0%, 98.7%, and 99.3% respectively.

[0133] Example 5

[0134] The main components of the deep-sea manganese nodules in this example include MnO2 (39.5%), SiO2 (18.8%), Fe2O3 (5.1%), Al2O3 (4.7%), MgO (1.7%), CaO (3.0%), Na2O (1.6%), NiO (1.1%), CuO (1.1%), and Co2O3 (0.22%).

[0135] (1)Microwave preheating activation: Take 100 g of raw deep-sea manganese nodules and perform microwave preheating activation. The microwave power is 500 W and the frequency is 2.75 GHz. Use microwave heating to raise the temperature of the raw ore to 480 °C. Keep the microwave frequency unchanged and adjust the microwave power to keep the raw ore at 480 °C for heat preservation treatment for 30 min to obtain activated manganese nodules;

[0136] (2)Grinding and premixing: Grind the activated manganese nodules to obtain ore powder of about 0.8 mm. Take 100 g of deep-sea manganese nodule ore powder and mix it with 90 g of high-grade matte as a reducing agent to obtain premixed activated ore powder;

[0137] (3)Microwave reduction and acid leaching: In a microwave environment, add leaching agent sulfuric acid and high-grade matte as a reducing agent to the premixed activated ore powder for reduction activation leaching. The microwave power is 180 W and the frequency is 2.7 GHz. Use microwave heating to raise the temperature of the leaching system to 95 °C, then keep the microwave frequency unchanged and adjust the microwave power to carry out heat preservation leaching at this temperature for 60 min; for every 1 g of premixed activated ore powder, it corresponds to 10 mL of acid leaching solution; the sulfuric acid concentration is 1.4 mol / L; obtain a microwave acid leaching solution containing ions such as Mn, Co, Ni, Cu, Fe and an iron-containing acid leaching residue; there are still impurities in this microwave acid leaching solution. Besides the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, it also includes compounds containing elements such as Si, Al, Mg, Ca, Na, etc.; the recovery rate of Mn in the microwave acid leaching solution is 95.1%, the recovery rate of Fe is 7.7%, and the recovery rates of other valuable metals Ni, Cu, Co are approximately 87.5%, 89.6%, 88.7% respectively;

[0138] (4)Sulfide precipitation: Dilute the microwave acid leaching solution to 1000 mL with water and add 68 g of sodium sulfite Na2SO3 to form a sulfide system; use NaOH as a pH regulator to adjust the pH of the sulfide system to 3.9. The sulfide reaction time is 60 min to form sulfide precipitates of Fe, Co, Cu, Ni ions and a small amount of Mn ions, obtaining a sulfide manganese removal slag containing sulfide precipitates and a manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the sulfide manganese removal slag together and become the impurities in the sulfide manganese removal slag; filter and dry the sulfide manganese removal slag for standby. The recovery rates of Fe, Co, Cu, Ni are approximately 96.1%, 96.6%, 96.7%, 97.0% respectively;

[0139] (5) Microwave sulfide smelting: In a microwave environment, 105 g of reducing agent carbon powder and 80 g of sulfiding agent CaSO4 are added to the manganese sulfide removal slag to form a smelting system for smelting. Using microwave heating with a power of 1300 W and a frequency of 2.8 GHz, the smelting system is rapidly heated to 1300 °C. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 100 min. Copper, nickel, cobalt, a small amount of Mn, and a small part of iron in the manganese sulfide removal slag are sulfided to form a low-grade matte phase (grade 50%). Most of the iron and impurities in the manganese sulfide removal slag enter the slag phase to form sulfide smelting slag;

[0140] (6) Oxygen-enriched blowing: Use an oxygen lance to conduct the first-stage blowing on the low-grade matte and sulfide smelting slag, with an oxygen pressure of 250 kPa and an oxygen-enriched concentration of 60%, and the blowing time is 100 min. After separating and removing the first-stage blowing slag, conduct the second-stage blowing, with an oxygen pressure of 190 kPa and an oxygen-enriched concentration of 50%. When the matte grade reaches 70%, the second-stage blowing ends, and high-grade matte is obtained; The second-stage blowing slag is returned to step (5) for microwave sulfide smelting and recycling. The recovery rate of Fe in the first-stage blowing slag in the oxygen-enriched blowing step is about 94.9%;

[0141] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to conduct roasting and desulfurization treatment on the high-grade matte, with a microwave power of 750 W and a frequency of 2.75 GHz, so that the temperature of the high-grade matte is 750 °C. Keep the microwave frequency unchanged and adjust the microwave power, and keep it at this temperature for 90 min for heat preservation treatment; After the roasting is completed, add the roasting product to the reaction kettle. Under the pressure of pure oxygen with an oxygen pressure of 550 kPa, 10 mL of leaching agent is used for every 1 g of roasting product, and 1.4 mol / L sulfuric acid is used as the leaching agent. Use microwave heating with a power of 160 W and a frequency of 2.6 GHz to rapidly heat the oxygen pressure leaching system to 200 °C. Keep the microwave frequency unchanged and adjust the microwave power, and keep it at this temperature for 120 min for leaching. After the leaching is completed, solid-liquid separation is carried out to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 96.7%, 97.2%, and 96.9% respectively;

[0142] (8) Multi-stage extraction: Add the oxygen pressure leaching solution to a multi-stage extraction device. First, extract manganese with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, extract copper from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, extract cobalt from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, extract nickel from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate. During the extraction process, the concentration of the extractant is 30% (sulfonated kerosene as the diluent), the ratio of the extraction phase to the stripping phase is 2.5, the mixing time is 15 min, the phase separation time is 15 min, the number of extraction and stripping stages is 9, and 6% sulfuric acid is used as the stripping agent. The extraction rates of Ni, Co, Cu, and Mn are 98.9%, 99.2%, 98.9%, and 99.5% respectively.

[0143] Example 6

[0144] The main components of the deep-sea manganese nodules in this example include MnO2 (39.7%), SiO2 (15.7%), Fe2O3 (6.8%), Al2O3 (5.9%), MgO (4.2%), CaO (4.7%), Na2O (2.2%), NiO (2.6%), CuO (1.9%), and Co2O3 (0.27%).

[0145] (1) Microwave preheating and activation: Take 100 g of the original deep-sea manganese nodule ore and perform microwave preheating and activation. The microwave power is 500 W and the frequency is 2.8 GHz. Use microwave heating to raise the temperature of the original ore to 500 °C, keep the microwave frequency unchanged and adjust the microwave power to keep the original ore at 500 °C for heat preservation treatment for 30 min to obtain activated manganese nodules.

[0146] (2) Grinding and premixing: Grind the activated manganese nodules to obtain ore powder of about 0.8 mm. Take 100 g of the deep-sea manganese nodule ore powder and mix it with 100 g of the high-grade matte reductant to obtain premixed activated ore powder.

[0147] (3)Microwave reduction acid leaching: In a microwave environment, leaching agent sulfuric acid and reducing agent high-grade matte are added to the premixed activated ore powder for reduction activation leaching. The microwave power is 200 W and the frequency is 2.8 GHz. After the temperature of the leaching system reaches 100 °C by microwave heating, the microwave power is adjusted while keeping the microwave frequency unchanged, and the leaching is carried out at this temperature for 60 min; for every 1 g of premixed activated ore powder, there is 10 mL of acid leaching solution; the sulfuric acid concentration is 1.6 mol / L; a microwave acid leaching solution containing ions such as Mn, Co, Ni, Cu, and Fe and an acid leaching residue containing Fe are obtained; there are still impurities in this microwave acid leaching solution. Besides the compounds containing elements such as Mn, Co, Ni, Cu, and Fe that are not completely leached, the impurities also include compounds containing elements such as Si, Al, Mg, Ca, and Na; the recovery rate of Mn in the microwave acid leaching solution is 95.5%, the recovery rate of Fe is 7.4%, and the recovery rates of other valuable metals Ni, Cu, and Co are approximately 87.9%, 89.9%, and 89.1% respectively;

[0148] (4)Sulfide precipitation: The microwave acid leaching solution is diluted to 1000 mL with water and 80 g of sodium sulfite Na2SO3 is added to form a sulfide system; NaOH is used as the pH regulator to adjust the pH of the sulfide system to 5. The sulfide reaction time is 60 min to form sulfide precipitates of ions such as Fe, Co, Cu, Ni and a small amount of Mn ions, obtaining a sulfide manganese removal slag containing sulfide precipitates and a manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the sulfide manganese removal slag and become the impurities in the sulfide manganese removal slag; the sulfide manganese removal slag is filtered and dried for standby. The recovery rates of Fe, Co, Cu, and Ni are approximately 96.3%, 96.8%, 96.9%, and 97.3% respectively;

[0149] (5)Microwave sulfide smelting: In a microwave environment, 120 g of reducing agent carbon powder and 80 g of sulfiding agent CaSO4 are added to the sulfide manganese removal slag to form a smelting system for smelting. The microwave with a power of 1300 W and a frequency of 2.8 GHz is used to heat the smelting system to quickly rise to 1300 °C. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 120 min, so that copper, nickel, cobalt, a small amount of Mn and a small part of iron in the sulfide manganese removal slag are sulfided to form a low-grade matte phase (grade 50%), and most of the iron and impurities in the sulfide manganese removal slag enter the slag phase to form a sulfide smelting slag;

[0150] (6)Oxygen-enriched blowing: Use an oxygen lance to conduct one-stage blowing on low-grade matte and sulfide smelting slag. The oxygen pressure is 250 kPa, the oxygen-enriched concentration is 60%, and the blowing time is 120 min. After separating and removing the one-stage blowing slag, conduct two-stage blowing. The oxygen pressure is 200 kPa, and the oxygen-enriched concentration is 50%. When the matte grade reaches 70%, the two-stage blowing ends, and high-grade matte is obtained. Return the two-stage blowing slag to step (5) for microwave sulfide smelting for recycling. The recovery rate of Fe in the one-stage blowing slag in the oxygen-enriched blowing step is approximately 95.1%;

[0151] (7)Microwave roasting oxygen pressure leaching: Use microwave heating to conduct roasting and desulfurization treatment on high-grade matte. The microwave power is 800 W, the frequency is 2.8 GHz, so that the temperature of the high-grade matte is 800 °C. Keep the microwave frequency unchanged and adjust the microwave power. Conduct heat preservation treatment at this temperature for 100 min. After roasting, add the roasted product to a reaction kettle. Under the pressure of pure oxygen with an oxygen pressure of 600 kPa, use 10 mL of leaching agent for every 1 g of roasted product. 1.6 mol / L sulfuric acid is used as the leaching agent. Use microwave heating with a power of 200 W and a frequency of 2.8 GHz to quickly raise the temperature of the oxygen pressure leaching system to 200 °C. Keep the microwave frequency unchanged and adjust the microwave power. Conduct heat preservation leaching at this temperature for 150 min. After leaching, obtain oxygen pressure leaching solution and oxygen pressure leaching slag through solid-liquid separation. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 96.9%, 97.4%, and 97.1% respectively;

[0152] (8)Multistage extraction: Add the oxygen pressure leaching solution to a multistage extraction device. First, extract manganese with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, extract copper from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, extract cobalt from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, extract nickel from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate. During the extraction process, the concentration of the extractant is 30% (sulfonated kerosene is used as the diluent). The ratio of the extraction phase to the stripping phase is 2.5, the mixing time is 15 min, the phase separation time is 15 min, the number of extraction and stripping stages is 9, and 6% sulfuric acid is used as the stripping agent. The extraction rates of Ni, Co, Cu, and Mn are 99.0%, 99.3%, 99.0%, and 99.6% respectively.

[0153] Comparative Example 1

[0154] Change the conditions of microwave treatment in each step, and the remaining steps are the same as those in Example 1.

[0155] The main components of the deep-sea manganese nodules in this comparative example include MnO2 (25.9%), SiO2 (16.3%), Fe2O3 (7.6%), Al2O3 (4.3%), MgO (3.7%), CaO (4.5%), Na2O (1.2%), NiO (1.1%), CuO (1.1%), and Co2O3 (0.19%).

[0156] 1) Microwave preheating activation: Take 100 g of the original deep-sea manganese nodule ore, and perform microwave preheating activation. The microwave power is 100 W, the frequency is 2.0 GHz. Use microwave heating to raise the temperature of the original ore to 200 °C. Keep the microwave frequency unchanged and adjust the microwave power to keep the original ore at 200 °C for heat preservation treatment for 15 min to obtain activated manganese nodules;

[0157] 2) Grinding and premixing: Grind the activated manganese nodules to obtain ore powder of about 0.8 mm. Take 100 g of the deep-sea manganese nodule ore powder and mix it with 30 g of the high-grade matte reductant to obtain premixed activated ore powder;

[0158] 3) Microwave reduction and acid leaching: In a microwave environment, add the leaching agent sulfuric acid and the high-grade matte reductant to the premixed activated ore powder for reduction activation leaching. The microwave power is 90 W, the frequency is 2.0 GHz. Use microwave heating to raise the temperature of the leaching system to 50 °C, then keep the microwave frequency unchanged and adjust the microwave power, and perform heat preservation leaching at this temperature for 20 min; for every 1 g of premixed activated ore powder, there are 7 mL of acid leaching solution; the sulfuric acid concentration is 0.6 mol / L; obtain a microwave acid leaching solution containing Mn, Co, Ni, Cu, Fe and other ions and an iron-containing acid leaching residue; there are still impurities in this microwave acid leaching solution. In addition to the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, it also includes compounds containing elements such as Si, Al, Mg, Ca, Na, etc.; the Mn recovery rate in the microwave acid leaching solution is 75.7%, the Fe recovery rate is 9.4%, and the recovery rates of other valuable metals Ni, Cu, Co are approximately 74.3%, 74.1%, 74.5% respectively;

[0159] 4) Sulfide precipitation: Dilute the microwave acid leaching solution with water to a volume of 1000 mL and add 30 g of sodium sulfite Na2SO3 to form a sulfide system; use citric acid as a pH regulator to adjust the pH of the sulfide system to 2. The sulfide reaction time is 30 min to form sulfide precipitates of Fe, Co, Cu, Ni and other ions and a small amount of Mn ions, obtaining a sulfide manganese removal slag containing sulfide precipitates and a manganese-rich sulfide solution containing a large amount of Mn ions; the impurities in the microwave acid leaching solution also precipitate into the sulfide manganese removal slag together and become the impurities in the sulfide manganese removal slag; filter and dry the sulfide manganese removal slag for standby. The recovery rates of Fe, Co, Cu, Ni are approximately 76.4%, 76.8%, 76.4%, 77.1% respectively;

[0160] (5) Microwave sulfide smelting: In a microwave environment, 68 g of reducing agent carbon powder and 62 g of sulfiding agent CaSO4 are added to the manganese sulfide removal slag to form a smelting system for smelting. The smelting system is rapidly heated to 1000 °C by microwave heating with a power of 700 W and a frequency of 2.2 GHz. After reaching the smelting temperature, the microwave power is adjusted while keeping the microwave frequency unchanged, and the smelting system is kept at this temperature for 50 min. Copper, nickel, cobalt, a small amount of Mn, and a small part of iron in the manganese sulfide removal slag are sulfided to form a low-grade matte phase (grade 30%). Most of the iron and impurities in the manganese sulfide removal slag enter the slag phase to form sulfide smelting slag;

[0161] (6) Oxygen-enriched blowing: Use an oxygen lance to conduct one-stage blowing on the low-grade matte and sulfide smelting slag, with an oxygen pressure of 200 kPa and an oxygen-enriched concentration of 50%, and a blowing time of 60 min. After separating and removing the one-stage blowing slag, conduct two-stage blowing, with an oxygen pressure of 150 kPa and an oxygen-enriched concentration of 40%. When the matte grade reaches 60%, the two-stage blowing ends, and high-grade matte is obtained; The two-stage blowing slag is returned to step (5) for microwave sulfide smelting and recycling. The recovery rate of Fe in the one-stage blowing slag in the oxygen-enriched blowing step is approximately 75.3%;

[0162] (7) Microwave roasting oxygen pressure leaching: Use microwave heating to conduct roasting and desulfurization treatment on the high-grade matte, with a microwave power of 400 W and a frequency of 2.2 GHz, so that the temperature of the high-grade matte is 400 °C. The microwave power is adjusted while keeping the microwave frequency unchanged, and it is kept at this temperature for 20 min for heat preservation treatment; After the roasting ends, add the roasting product to the reaction kettle. Under the pressure of pure oxygen with an oxygen pressure of 100 kPa, 7 mL of leaching agent is used per 1 g of roasting product, and 0.6 mol / L sulfuric acid is used as the leaching agent. The oxygen pressure leaching system is rapidly heated to 150 °C by microwave heating with a power of 90 W and a frequency of 2.0 GHz. The microwave power is adjusted while keeping the microwave frequency unchanged, and it is kept at this temperature for 60 min for leaching. After the leaching ends, solid-liquid separation is carried out to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 77.7%, 78.6%, and 79.0% respectively;

[0163] (8) Multi-stage extraction: Add the oxygen pressure leaching solution to a multi-stage extraction device. First, extract manganese with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, extract copper from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, extract cobalt from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, extract nickel from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate; during the extraction process, the concentration of the extractant is 10% (sulfonated kerosene is used as the diluent), the ratio of the extraction phase to the stripping phase is 0.5, the mixing time is 5 min, the phase separation time is 5 min, the number of extraction and stripping stages is 3, and sulfuric acid with a concentration of 6% is used as the stripping agent; the extraction rates of Ni, Co, Cu, and Mn are 79.0%, 78.3%, 79.2%, and 79.3% respectively.

[0164] Comparative Example 2

[0165] Microwave is not used in each step, and only conventional methods are used to treat deep-sea manganese nodules, and the remaining steps are the same as those in Example 6.

[0166] The main components of the deep-sea manganese nodules in this comparative example include MnO2 (39.7%), SiO2 (15.7%), Fe2O3 (6.8%), Al2O3 (5.9%), MgO (4.2%), CaO (4.7%), Na2O (2.2%), NiO (2.6%), CuO (1.9%), and Co2O3 (0.27%).

[0167] (1) No microwave preheating and activation treatment;

[0168] (2) Grinding and premixing: Grind the manganese nodules to obtain mineral powder with a particle size of about 0.8 mm. Take 100 g of deep-sea manganese nodule mineral powder and mix it with 100 g of high-grade matte as the reducing agent to obtain premixed mineral powder;

[0169] (3) Reduction acid leaching: Add the leaching agent sulfuric acid and high-grade matte as the reducing agent to the premixed mineral powder for reduction activation leaching; for every 1 g of premixed mineral powder, 10 mL of acid leaching solution is used; the concentration of sulfuric acid is 1.6 mol / L; obtain an acid leaching solution containing Mn, Co, Ni, Cu, Fe and other ions and an acid leaching residue containing Fe; there are still impurities in this acid leaching solution, and these impurities include not only the compounds containing Mn, Co, Ni, Cu, Fe elements that are not completely leached, but also the compounds containing Si, Al, Mg, Ca, Na and other elements; the recovery rate of Mn in the acid leaching solution is 75.4%, the recovery rate of Fe is 10.4%, and the recovery rates of other valuable metals Ni, Cu, and Co are about 67.6%, 69.3%, and 68.2% respectively;

[0170] (4)Sulfide precipitation: Dilute the acid leaching solution with water to a constant volume of 1000 mL, and add 80 g of sodium sulfite (Na2SO3) to form a sulfide system. Use NaOH as the pH regulator to adjust the pH of the sulfide system to 5. The sulfide reaction time is 60 min to form sulfide precipitates of Fe, Co, Cu, Ni ions and a small amount of Mn ions, obtaining sulfide manganese removal slag containing sulfide precipitates and manganese-rich sulfide solution containing a large amount of Mn ions. The impurities in the acid leaching solution also precipitate into the sulfide manganese removal slag and become the impurities in the sulfide manganese removal slag. Filter and dry the sulfide manganese removal slag for standby. The recovery rates of Fe, Co, Cu, and Ni are approximately 66.1%, 66.5%, 66.3%, and 67.5% respectively;

[0171] (5)Sulfide smelting: Add 120 g of reducing agent carbon powder and 80 g of sulfiding agent CaSO4 to the sulfide manganese removal slag to form a smelting system for smelting. Rapidly heat the muffle furnace to 1300 °C, and keep the smelting system at this temperature for 120 min, so that copper, nickel, cobalt, a small amount of Mn, and a small part of iron in the sulfide manganese removal slag are sulfided to form a low-grade matte phase (grade 50%). Most of the iron and impurities in the sulfide manganese removal slag enter the slag phase to form sulfide smelting slag;

[0172] (6)Oxygen-enriched blowing: Use an oxygen lance to conduct the first-stage blowing on the low-grade matte and sulfide smelting slag, with an oxygen pressure of 250 kPa and an oxygen-enriched concentration of 60%. After separating and removing the first-stage blowing slag, conduct the second-stage blowing, with an oxygen pressure of 200 kPa and an oxygen-enriched concentration of 50%. When the matte grade reaches 70%, the second-stage blowing ends to obtain high-grade matte. Return the second-stage blowing slag to step (5) for sulfide smelting and recycling. The recovery rate of Fe in the first-stage blowing slag in the oxygen-enriched blowing step is approximately 65.3%;

[0173] (7)Oxygen pressure leaching: Add the high-grade matte to the reaction kettle. Under the pressure of pure oxygen at 600 kPa, use 10 mL of leaching agent for every 1 g of high-grade matte, and 1.6 mol / L sulfuric acid as the leaching agent. Heat with an electric resistance furnace to 200 °C and keep it at this temperature for leaching for 150 min. After leaching, perform solid-liquid separation to obtain oxygen pressure leaching solution and oxygen pressure leaching slag. The recovery rates of Co, Cu, and Ni in the oxygen pressure leaching solution are 76.7%, 77.4%, and 77.5% respectively;

[0174] (8) Multi-stage extraction: The oxygen pressure leaching solution is added to a multi-stage extraction device. First, manganese is extracted with P204 to obtain a manganese-containing extraction solution and a manganese-removed raffinate. Then, copper is extracted from the manganese-removed raffinate with Lix984 to obtain a copper-containing extraction solution and a copper-removed raffinate. Next, cobalt is extracted from the copper-removed raffinate with Cyanex272 to obtain a cobalt-containing extraction solution and a cobalt-removed raffinate. Finally, nickel is extracted from the cobalt-removed raffinate with P507 to obtain a nickel-containing extraction solution and a nickel-removed raffinate; during the extraction process, the concentration of the extractant is 30% (sulfonated kerosene is used as the diluent), the ratio of the extraction phase to the stripping phase is 2.5, the mixing time is 15 min, the phase separation time is 15 min, the number of extraction and stripping stages is 9, and 6% sulfuric acid is used as the stripping agent; the extraction rates of Ni, Co, Cu, and Mn are 76.2%, 77.3%, 78.1%, and 79.9% respectively.

Claims

1. A method for treating manganese nodules with microwaves, characterized in that: Includes the following: (1) Microwave preheating activation: The manganese nodule ore is preheated and activated by microwaves, so that the structure of manganese agglomerates in the ore is destroyed, and the gas phase components in the ore overflow to obtain activated manganese nodules; (2) Grinding and premixing: Grinding the activated manganese nodules prepared in step (1) to obtain activated manganese nodule ore powder, adding a reducing agent, high-grade matte, to the activated manganese nodule ore powder and mixing to obtain a premixed activated ore powder; (3) Microwave reduction acid leaching: under a microwave environment, sulfuric acid as a leaching agent and high-grade matte as a reducing agent are added to the premixed activated ore powder obtained in step (2) to form a leaching system for reduction activation leaching to obtain a microwave acid leaching solution containing Mn, Co, Ni, Cu, Fe ions and impurities and Fe-containing acid leaching residue; Reduction activation leaching causes the MnO2 and Co2O3 mineral phases in the ore powder to be dissociated and reconstructed into soluble MnSO4 and CoSO4. At the same time, the free CuO and NiO minerals are converted into copper sulfate and nickel sulfate by sulfuric acid leaching; (4) Sulfidation precipitation: adding a sulfidation precipitant to the microwave acid leaching solution obtained in step (3) to form a sulfidation system, wherein Fe, Co, Cu, Ni and part of the Mn ions in the sulfidation system form sulfidation precipitates, thereby obtaining a sulfidation demanganeseized slag containing sulfidation precipitates and impurities and a manganese-rich sulfidation solution mainly containing Mn ions; (5) Microwave sulfidation smelting: adding a reducing agent and a sulfiding agent to the sulfidation demanganization slag obtained in step (4) under a microwave environment to form a smelting system for sulfidation smelting to obtain low-grade matte and sulfidation smelting slag; Among them, low-grade matte is mainly formed by the sulfidation of Cu, Ni, Co, part of Mn and part of Fe in the sulfidation demanganese slag; sulfidation smelting slag is mainly formed by part of the iron and impurities in the sulfidation demanganese slag entering the slag phase; (6) Oxygen-enriched blowing: the low-grade matte and sulfide smelting slag obtained in step (5) are subjected to a first-stage blowing, and after the first-stage blowing slag is separated, a second-stage blowing is continued, and after the second-stage blowing slag is separated, a high-grade matte is obtained; (7) Microwave roasting and oxygen pressure leaching: roasting and desulfurizing the high-grade matte obtained in step (6) by microwave heating to obtain a roasting product; performing oxygen pressure leaching on the roasting product under a microwave environment, and obtaining an oxygen pressure leaching liquid and an oxygen pressure leaching slag by solid-liquid separation after the leaching is completed; (8) Multi-stage extraction: The oxygen pressure leaching solution obtained in step (7) is extracted to separate manganese, copper, nickel and cobalt.

2. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: The specific method of step (1) microwave preheating activation is as follows: using microwave heating with a power of 300W to 500W and a frequency of 2.3GHz to 2.8GHz to make the temperature of the raw ore 300°C to 500°C, adjusting the microwave power while keeping the microwave frequency unchanged, and keeping the temperature at this temperature for 20min to 30min, so that the structure of manganese agglomerates in the raw ore is destroyed and the gas phase components overflow, thereby obtaining activated manganese nodules; The microwave environment in step (3) refers to using microwave heating with a power of 100 W to 200 W and a frequency of 2.3 GHz to 2.8 GHz to make the temperature of the reduction activation leaching system 60° C. to 100° C., then adjusting the microwave power while keeping the microwave frequency unchanged, and maintaining the temperature for 30 min to 60 min to perform reduction activation leaching.

3. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: In step (2), 30 g to 100 g of high-grade matte is added for every 100 g of activated manganese nodule ore powder; In step (3), 30 g to 100 g of high-grade matte is added for every 100 g of premixed activated ore powder, and 7 mL to 10 mL of sulfuric acid is added for every 1 g of premixed activated ore powder, and the concentration of sulfuric acid is 0.6 mol / L to 1.6 mol / L; The grade of the high-grade matte in steps (2) and (3) is 60%-75%, and the main components are as follows: Cu 60%-70%, S 20%-25%, Fe 5%-15%.

4. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: In step (4): The sulfide precipitant includes one or more of H2S, Na2S, NaHS, and Na2SO3; For every 1000mL of microwave acid leaching solution, 30g~80g of sulfide precipitation agent is added, and the sulfide precipitation time is 30min~60min; The pH of the vulcanization system is adjusted to 2-5 by a pH regulator; the pH regulator includes at least one of NaOH, NH3·H2O, NH4Cl, and citric acid.

5. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: In step (5): The microwave environment refers to using microwave heating with a power of 900W to 1300W and a frequency of 2.3GHz to 2.8GHz to make the temperature of the melting system 1100°C to 1300°C, and after reaching the melting temperature, the microwave frequency is kept unchanged and the microwave power is adjusted to keep the melting system at this temperature for 60min to 120min for melting; The grade of the low-grade matte is 40% to 50%; The mass of the mixture of reducing agent and sulfiding agent added to every 100g of sulfiding demanganizing slag is 130g~200g, of which the mass of reducing agent is 68g~120g; The reducing agent is carbon powder, and the vulcanizing agent is CaSO4.

6. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: In step (6): The oxygen pressure of the first stage blowing is 200kPa-250kPa, the oxygen enrichment concentration is 50%-60%, the first stage blowing time is 60min-120min, and when the matte phase grade reaches 50%-60%, the first stage blowing slag is separated and the second stage blowing is continued; The oxygen pressure of the second stage blowing is 150kPa-200kPa, the oxygen enrichment concentration is 40%-50%, the second stage blowing time is 30min-60min, and the blowing end point is when the matte phase grade reaches 60%-75%, that is, high-grade matte is obtained.

7. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: In step (7): The microwave conditions used in roasting and desulfurization are as follows: microwave power 500W~800W, frequency 2.3GHz~2.8GHz, use microwave heating to make the temperature of high-grade matte 500℃~800℃, keep the microwave frequency unchanged and adjust the microwave power, so that the high-grade matte is roasted at this temperature for 30min~120min; The microwave conditions used in oxygen pressure leaching are as follows: first, use microwave heating with a power of 100W to 200W and a frequency of 2.3GHz to 2.8GHz to make the temperature of the oxygen pressure leaching system 160℃ to 200℃, keep the microwave frequency unchanged and adjust the microwave power, so that the leaching system is kept at this temperature for 60min to 150min for oxygen pressure leaching; During oxygen pressure leaching, the pure oxygen pressure is 100kPa~700kPa, sulfuric acid is used as the leaching solution, the sulfuric acid concentration is 0.6mol / L~1.6mol / L, and 7mL~10mL of leaching solution is used for every 1g of roasted product.

8. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: The specific extraction method in step (8) is as follows: First, manganese is extracted from the oxygen pressure leaching solution by using P204 to obtain a manganese-containing extract and a manganese-removed raffinate, and then copper is extracted from the manganese-removed raffinate by using Lix984 to obtain a copper-containing extract and a copper-removed raffinate, and then cobalt is extracted from the copper-removed raffinate by using Cyanex272 to obtain a cobalt-containing extract and a cobalt-removed raffinate, and finally nickel is extracted from the cobalt-removed raffinate by using P507 to obtain a nickel-containing extract and a nickel-removed raffinate; The concentration of the extractant is 10%~30%, sulfonated kerosene is the diluent; the extraction phase ratio is 0.5~2.5, the mixing time is 5min~15min, the phase separation time is 5min~15min, and the extraction level is 3~9; the back extraction uses an aqueous solution of H2SO4 or NaOH.

9. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: The impurities in the microwave acid leaching solution in step (3) include compounds containing Mn, Co, Ni, Cu, and Fe elements that are not completely leached out of the premixed activated ore powder, as well as compounds containing Si, Al, Mg, Ca, and Na elements; The impurities in the sulfidation demanganization slag in step (4) are formed by the impurities in the microwave acid leaching solution in step (3) being precipitated into the sulfidation demanganization slag during the sulfidation precipitation process; The impurities in the sulfidation smelting slag in step (5) are formed by the impurities in the sulfidation demanganization slag in step (4) entering the slag phase during the sulfidation smelting process.

10. The method for microwave treatment of manganese nodules according to claim 1, characterized in that: The Fe-containing acid leaching residue in step (3) is further used to deeply extract the unleached Mn, Co, Ni, Cu, and Fe, or used as cement aggregate or building material; The manganese-rich sulfide liquid obtained in step (4) is distilled to obtain a manganese sulfate product; The high-grade matte obtained in step (6) is returned to step (2) and step (3) for use; the separated second-stage blowing slag is returned to step (5) for microwave sulfidation smelting and recycling; In step (7), the SO2 generated by the roasting desulfurization treatment is absorbed, and the obtained Na2SO3 is recycled as a sulfide precipitant in step (4); the oxygen pressure leaching slag separated after oxygen pressure leaching is deeply purified to separate Mn, Co, Ni, Cu, Fe, or used as cement aggregate or building material.

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