Method for leaching nickel, cobalt, manganese and molybdenum step by step and nickel, cobalt, manganese and molybdenum raw material

Abstract

The invention provides a method for leaching nickel, cobalt, manganese and molybdenum step by step and a nickel, cobalt, manganese and molybdenum raw material, and the method comprises the following steps: carrying out heat treatment on nickel, cobalt, manganese and molybdenum waste, cooling, and sequentially carrying out alkaline leaching and acid leaching to obtain a leaching solution containing nickel, cobalt, manganese and molybdenum; the cooling rate is 80-120 DEG C / s. According to the preparation method, volatile impurities in the nickel-cobalt-manganese-molybdenum waste are removed through heat treatment, the leaching activity of the nickel-cobalt-manganese-molybdenum waste is improved, microcracks of the nickel-cobalt-manganese-molybdenum waste are increased through rapid cooling, alkaline leaching and acid leaching are matched, the leaching rate in the alkaline leaching and acid leaching process is increased, the leaching effect is improved, and the method is suitable for industrial production. Therefore, the content of impurities in the finally obtained leachate containing nickel, cobalt, manganese and molybdenum is low, and the recovery rate of nickel, cobalt, manganese and molybdenum is high. In addition, the preparation method is simple in step and low in requirement, so that the preparation method further has the advantages of being simple in recovery process and low in recovery cost.

Description

Technical Field

[0001] The present invention belongs to the technical field, and relates to a method for stepwise leaching of nickel, cobalt, manganese and molybdenum, and particularly relates to a method for stepwise leaching of nickel, cobalt, manganese and molybdenum and raw materials of nickel, cobalt, manganese and molybdenum. Background Art

[0002] Lithium-ion batteries are widely used in the fields of consumer electronics and new energy vehicles due to their excellent electrochemical performance. However, with the explosive growth of the new energy vehicle industry, the amount of retired batteries has also increased significantly, posing dual challenges to the environment and resources. On the one hand, if waste batteries are not properly disposed of, the heavy metals (such as nickel, cobalt, manganese and molybdenum) contained therein will seriously pollute the soil and water bodies; on the other hand, nickel, cobalt, manganese and molybdenum are important metal resources, and the metal content in waste batteries is much higher than that in primary ores, and efficient recovery is urgently needed to alleviate the shortage of resources.

[0003] Currently, the mainstream recovery technologies include pyrometallurgy and hydrometallurgy. Among them, pyrometallurgy removes the binder through high-temperature roasting, but has high energy consumption and generates harmful gases; hydrometallurgy has become the mainstream process due to its low energy consumption and high efficiency. Its process includes steps such as acid leaching, extraction, precipitation, etc. For example, reduction acid leaching combined with extraction-stripping can separate metal salts, but there are problems such as complex process, high impurity content and low recovery rate.

[0004] CN113957247A discloses a method for recovering valuable metals from electrode waste containing nickel, cobalt, tungsten, oxygen and lithium. The method includes the following steps: mixing the electrode waste with a reducing agent, and performing thermal grinding or calcination treatment under a flowing atmosphere condition to obtain a mixed material; leaching the obtained mixed material with water and separating to obtain a lithium-containing solution and a primary filter residue; performing alkali leaching on the obtained primary filter residue and separating to obtain a tungsten-containing solution and a secondary filter residue. However, the recovery rate of this method is relatively low, and the impurity content in the recovered product is relatively high.

[0005] CN108258355A discloses a method applicable to the recycling of lithium iron phosphate / lithium nickel cobalt manganese oxide power batteries. In this method, the repair and recycling method of lithium iron phosphate / lithium nickel cobalt manganese oxide includes the following steps: forced discharge, primary crushing, forced extrusion, secondary crushing, air drying, vibration screening, high-temperature calcination, acid washing, alkali leaching, secondary air drying, determination of element content, secondary high-temperature calcination; the regeneration and recycling method of lithium iron phosphate includes the following steps: forced discharge, primary crushing, forced extrusion, secondary crushing, air drying, vibration screening, high-temperature calcination, acid washing, alkali leaching II, secondary air drying II; the regeneration and recycling method of lithium nickel cobalt manganese oxide includes the following steps: forced discharge, primary crushing, forced extrusion, secondary crushing, air drying, vibration screening, high-temperature calcination, acid washing, electroplating, adding carbonate ions; however, the process of this method is complex and the cost is relatively high, which is not conducive to large-scale popularization and use.

[0006] The methods for recovering nickel, cobalt, manganese, and molybdenum from nickel-cobalt-manganese-molybdenum waste materials disclosed in the prior art all have certain defects, such as complex recovery processes, high recovery costs, high impurity content in the recovered materials, and low recovery rates. Therefore, it is crucial to develop and design a new method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum and nickel-cobalt-manganese-molybdenum raw materials. In the preparation method of the present invention, volatile impurities in the nickel-cobalt-manganese-molybdenum waste materials are removed through heat treatment, and the leaching activity of the nickel-cobalt-manganese-molybdenum waste materials is improved. Microcracks in the nickel-cobalt-manganese-molybdenum waste materials are increased through rapid cooling, and then combined with alkali leaching and acid leaching, which not only improves the leaching rate in the alkali leaching and acid leaching processes, but also improves the leaching effect, so that the impurity content in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is low, and the recovery rate of nickel, cobalt, manganese, and molybdenum is high; in addition, the steps of the preparation method are simple and have low requirements, so it also has the advantages of simple recovery process and low recovery cost.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum, and the method includes:

[0010] Performing heat treatment on the nickel-cobalt-manganese-molybdenum waste materials and then cooling, and then successively performing alkali leaching and acid leaching to obtain a leaching solution containing nickel, cobalt, manganese, and molybdenum;

[0011] The cooling rate is 80-120 °C / s.

[0012] In the preparation method of the present invention, volatile impurities in the nickel-cobalt-manganese-molybdenum waste materials are removed through heat treatment, and the leaching activity of the nickel-cobalt-manganese-molybdenum waste materials is improved. Microcracks in the nickel-cobalt-manganese-molybdenum waste materials are increased through rapid cooling, and then combined with alkali leaching and acid leaching, which not only improves the leaching rate in the alkali leaching and acid leaching processes, but also improves the leaching effect, so that the impurity content in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is low, and the recovery rate of nickel, cobalt, manganese, and molybdenum is high; in addition, the steps of the preparation method are simple and have low requirements, so it also has the advantages of simple recovery process and low recovery cost.

[0013] In the present invention, the cooling rate is 80-120 °C / s, for example, it can be 80 °C / s, 85 °C / s, 90 °C / s, 95 °C / s, 100 °C / s, 105 °C / s, 110 °C / s, 115 °C / s or 120 °C / s, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0014] Preferably, the heat treatment includes: heating the nickel-cobalt-manganese-molybdenum waste successively with a first temperature rise, a first heat preservation, a second temperature rise and a second heat preservation in a protective atmosphere.

[0015] In the heat treatment of the present invention, volatile impurities in the waste are removed by the first heat preservation, and the leaching activity of the waste is enhanced by the second heat preservation, thereby reducing the impurity content in the finally obtained leaching solution containing nickel, cobalt, manganese and molybdenum and enhancing the recovery rate of nickel, cobalt, manganese and molybdenum.

[0016] Preferably, the rate of the first temperature rise is 2-5 °C / min, and the end temperature is 320-480 °C.

[0017] In the present invention, the rate of the first temperature rise is 2-5 °C / min. For example, it can be 2 °C / min, 2.5 °C / min, 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min or 5 °C / min, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0018] In the present invention, the end temperature of the first temperature rise is 320-480 °C. For example, it can be 320 °C, 340 °C, 360 °C, 380 °C, 400 °C, 420 °C, 440 °C, 460 °C or 480 °C, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] Preferably, the time of the first heat preservation is 40-80 min. For example, it can be 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min or 80 min, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0020] Preferably, the rate of the second temperature rise is 10-20 °C / min, and the end temperature is 520-680 °C.

[0021] In the present invention, the rate of the second temperature rise is 10-20 °C / min. For example, it can be 10 °C / min, 12 °C / min, 14 °C / min, 15 °C / min, 16 °C / min, 18 °C / min or 20 °C / min, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0022] In the present invention, the end temperature of the second temperature rise is 520-680 °C. For example, it can be 520 °C, 540 °C, 560 °C, 580 °C, 600 °C, 620 °C, 640 °C, 660 °C or 680 °C, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0023] Preferably, the time for the second heat preservation is 20 - 40 min. For example, it can be 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min or 40 min. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0024] Preferably, the end temperature for the cooling is 10 - 50 °C. For example, it can be 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C or 50 °C. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0025] Preferably, the method further includes mechanical activation between the cooling and the acid leaching.

[0026] In the method of the present invention, by subjecting the nickel - cobalt - manganese - molybdenum waste obtained after cooling to mechanical activation, defect sites are formed on the surface of the nickel - cobalt - manganese - molybdenum waste obtained after cooling, thereby further increasing the leaching rate of nickel, cobalt, manganese and molybdenum during the acid leaching and alkali leaching processes, and thus improving the recovery rate of nickel, cobalt, manganese and molybdenum.

[0027] Preferably, the manner of the mechanical activation includes ball milling. During the ball milling process, the mass ratio of the grinding aid to the nickel - cobalt - manganese - molybdenum waste obtained after cooling is (0.5 - 1):100, the rotation speed of the ball milling is 500 - 800 r / min, and the time is 5 - 15 min.

[0028] In the present invention, the mass ratio of the grinding aid to the nickel - cobalt - manganese - molybdenum waste obtained after cooling during the ball milling process is (0.5 - 1):100. For example, it can be 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0029] In the present invention, the rotation speed of the ball milling during the ball milling process is 500 - 800 r / min. For example, it can be 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min or 800 r / min. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0030] In the present invention, the ball milling time during the ball milling process is 5 to 15 minutes. For example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0031] Preferably, the grinding aid used in the ball milling includes any one or a combination of at least two of silica, alumina, or zirconia. Typical but non-limiting combinations include the combination of silica and alumina, the combination of alumina and zirconia, or the combination of silica, alumina, and zirconia.

[0032] Preferably, the alkali leaching agent used in the alkali leaching includes sodium carbonate, sodium hydroxide, and ammonia water with a molar ratio of (1.4 to 2.5):(0.1 - 0.5):1. The mass ratio of sodium carbonate, sodium hydroxide, and ammonia water can be, for example, 1.4:0.1:1, 1.6:0.2:1, 1.8:0.3:1, 2.0:0.4:1, or 2.5:0.5:1. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0033] Preferably, during the alkali leaching, the pH is maintained at 9.5 to 10.5, the temperature is 60 to 90 °C, and the time is 1 to 3 hours.

[0034] In the present invention, during the alkali leaching, the pH is maintained at 9.5 to 10.5. For example, it can be 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, or 10.5. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0035] In the present invention, the temperature during the alkali leaching is 60 to 90 °C. For example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, or 90 °C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0036] In the present invention, the time during the alkali leaching is 1 to 3 hours. For example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0037] In the method of the present invention, during the alkali leaching process, by controlling the pH to be stable at 9.5 - 10.5, the co - dissolution of iron and aluminum is inhibited, and the content of iron and aluminum impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is reduced, thereby improving the purity of the leaching solution containing nickel, cobalt, manganese, and molybdenum.

[0038] Preferably, an oxidizing agent is further added during the alkali leaching process, and the mass ratio of the oxidizing agent to the material to be treated input during alkali leaching is (0.1 - 0.5):100. For example, it can be 0.1:100, 0.2:100, 0.3:100, 0.4:100, or 0.5:100, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0039] In the present invention, molybdenum(IV) is oxidized to molybdenum(VI) by adding an oxidizing agent, thereby improving the leaching rate of molybdenum during the alkali leaching process and ultimately improving the recovery rate of molybdenum.

[0040] Preferably, the oxidizing agent includes any one or a combination of at least two of sodium persulfate, sodium chlorate, or hydrogen peroxide. Typical but non-limiting combinations include the combination of sodium persulfate and sodium chlorate, the combination of sodium chlorate and hydrogen peroxide, or the combination of sodium persulfate, sodium chlorate, and hydrogen peroxide.

[0041] Preferably, the method further includes membrane separation and recovery between the alkali leaching and acid leaching. After the membrane separation and recovery, a solid material and a leaching solution mainly composed of molybdenum are obtained.

[0042] Preferably, the separation membrane used for the membrane separation and recovery includes a nanofiltration membrane (NF) and / or a reverse osmosis membrane (RO).

[0043] Preferably, the method further includes: after molybdenum recovery from the leaching solution mainly composed of molybdenum, recovered molybdenum and a leaching agent to be recycled solution are obtained, and then the leaching agent to be recycled solution is subjected to leaching agent recovery.

[0044] Preferably, the method for molybdenum recovery includes: using a membrane separation technique to separate molybdenum from the leaching solution mainly composed of molybdenum, obtaining recovered molybdenum and a leaching agent to be recycled solution.

[0045] Preferably, the leaching agent recovery includes: adding a leaching agent with a mass of 8 - 15 wt% of the mass of the leaching agent to be recycled solution to the leaching agent to be recycled solution.

[0046] Preferably, the acid leaching agent used for the acid leaching includes sulfuric acid, and the pH during the acid leaching is 0.5 - 1.5, the temperature is 60 - 90 °C, and the time is 3 - 5 h.

[0047] In the present invention, the pH during the acid leaching is 0.5 - 1.5. For example, it can be 0.5, 0.7, 0.9, 1.1, 1.3, or 1.5, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0048] In the present invention, the temperature during acid leaching is 60 - 90 °C. For example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C or 90 °C, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0049] In the present invention, the time during acid leaching is 3 - 5 h. For example, it can be 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h or 5 h, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0050] In the method of the present invention, by limiting the pH during acid leaching to 0.5 - 1.5, the temperature to 60 - 90 °C and the time to 3 - 5 h, the leaching rate of nickel, cobalt, manganese and molybdenum is further improved, thereby improving the recovery rate of nickel, cobalt, manganese and molybdenum.

[0051] Preferably, the concentration of sulfuric acid is 1.0 - 2.5 mol / L. For example, it can be 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, 2.2 mol / L, 2.4 mol / L or 2.5 mol / L, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0052] Preferably, the method further includes selective impurity removal after the acid leaching.

[0053] Preferably, the selective impurity removal includes: after adjusting the pH of the acid leaching solution obtained after acid leaching to 2.0 - 3.0, adding an impurity removal agent with a mass of 0.03 - 0.1 wt% of the mass of the acid leaching solution after pH adjustment to obtain a leaching solution containing nickel, cobalt, manganese and molybdenum.

[0054] In the selective impurity removal of the present invention, the pH of the acid leaching solution obtained after acid leaching is adjusted to 2.0 - 3.0. For example, it can be 2.0, 2.2, 2.4, 2.6, 2.8 or 3.0, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0055] In the selective impurity removal of the present invention, an impurity removal agent with a mass of 0.03 - 0.1% of the mass of the acid leaching solution after pH adjustment is added. For example, it can be 0.03%, 0.04%, 0.05%, 0.06%, 0.07 wt%, 0.08%, 0.09% or 0.1%, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0056] In the method of the present invention, by adjusting the pH of the acid leaching solution obtained after acid leaching to 2.0 - 3.0 in selective impurity removal, precipitation of iron is achieved, and the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese and molybdenum is further reduced.

[0057] In the method of the present invention, in selective impurity removal, after adjusting the pH, a deimpurifying agent with a mass of 0.03 - 0.1% of the mass of the acid leaching solution after pH adjustment is added, and copper and lead impurities are selectively removed, further reducing the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese and molybdenum.

[0058] Preferably, the deimpurifying agent includes any one or a combination of at least two of sodium sulfide, ammonium sulfide or sodium hydroxide. Typical but non - restrictive combinations include the combination of sodium sulfide and ammonium sulfide, the combination of ammonium sulfide and sodium hydroxide, or the combination of sodium sulfide, ammonium sulfide and sodium hydroxide.

[0059] Preferably, the method further includes filtration after the selective impurity removal.

[0060] As a preferred technical solution of the method of the present invention, the method includes:

[0061] (1) Heating nickel - cobalt - molybdenum waste in a protective atmosphere at a rate of 2 - 5 °C / min to 320 - 480 °C, holding for 40 - 80 min, then heating at a rate of 10 - 20 °C / min to 520 - 680 °C, holding for 20 - 40 min, and then cooling at a rate of 80 - 120 °C / s to 10 - 50 °C to obtain the cooled nickel - cobalt - molybdenum waste;

[0062] (2) Mechanically activating the cooled nickel - cobalt - molybdenum waste obtained in step (1) by ball milling at a rotation speed of 500 - 800 r / min for 5 - 15 min to obtain the ball - milled nickel - cobalt - molybdenum waste; the mass ratio of the silica grinding aid to the cooled nickel - cobalt - molybdenum waste during the ball milling is (0.5 - 1):100;

[0063] (3) Using an alkali leaching agent including sodium carbonate, sodium hydroxide and ammonia water with a molar ratio of (1.4 - 2.5):(0.1 - 0.5):1 to perform alkali leaching on the ball - milled nickel - cobalt - molybdenum waste obtained in step (2) for 1 - 3 h, and then performing membrane separation and recovery to obtain solid materials and a leaching solution mainly composed of molybdenum; during the alkali leaching, the pH is maintained at 9.5 - 10.5 and the temperature is 60 - 90 °C; a sodium persulfate oxidant is also added during the alkali leaching process, and the mass ratio of the sodium persulfate oxidant to the ball - milled nickel - cobalt - molybdenum waste input during the alkali leaching is (0.1 - 0.5):100;

[0064] After recovering molybdenum from the obtained leaching solution mainly composed of molybdenum, recovered molybdenum and the alkali leaching agent to-be-recovered solution are obtained. Then, an alkali leaching agent with a mass of 8-15 wt% of the mass of the alkali leaching agent to-be-recovered solution is added to the obtained alkali leaching agent to-be-recovered solution to realize the recovery of the alkali leaching agent to-be-recovered solution;

[0065] (4) The solid material obtained in step (3) is subjected to acid leaching with sulfuric acid having a concentration of 1.0-2.5 mol / L for 3-5 h. The pH during the acid leaching is 0.5-1.5, and the temperature is 60-90 °C to obtain an acid leaching solution;

[0066] (5) After adjusting the pH of the acid leaching solution obtained in step (4) to 2.0-3.0, sodium sulfide with a mass of 0.03-0.1% of the mass of the acid leaching solution after pH adjustment is added, and after filtration, a leaching solution containing nickel, cobalt, manganese, and molybdenum is obtained.

[0067] In the second aspect, the present invention provides a nickel-cobalt-manganese-molybdenum raw material, which is obtained by the method described in the first aspect.

[0068] The numerical ranges described in the present invention not only include the exemplified point values above, but also any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the ranges.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] (1) In the preparation method described in the present invention, volatile impurities in the nickel-cobalt-manganese-molybdenum waste are removed by heat treatment, and the leaching activity of the nickel-cobalt-manganese-molybdenum waste is improved. By rapidly cooling, microcracks in the nickel-cobalt-manganese-molybdenum waste are increased. Combined with alkali leaching and acid leaching, not only the leaching rate in the alkali leaching and acid leaching processes is improved, but also the leaching effect is improved, so that the impurity content in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is low, and the recovery rate of nickel, cobalt, manganese, and molybdenum is high; in addition, the steps of the preparation method are simple and have low requirements, so it also has the advantages of simple recovery process and low recovery cost;

[0071] (2) In the heat treatment described in the present invention, volatile impurities in the waste are removed by the first heat preservation, and the leaching activity of the waste is improved by the second heat preservation, thereby reducing the impurity content in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum and improving the recovery rate of nickel, cobalt, manganese, and molybdenum;

[0072] (3) In the method described in the present invention, by mechanically activating the nickel-cobalt-manganese-molybdenum waste obtained after cooling, defect sites are formed on the surface of the nickel-cobalt-manganese-molybdenum waste obtained after cooling, thereby further improving the leaching rate of nickel, cobalt, manganese, and molybdenum in the acid leaching and alkali leaching processes, and thus improving the recovery rate of nickel, cobalt, manganese, and molybdenum;

[0073] (4) In the method of the present invention, during the alkali leaching process, by controlling the pH to be stable at 9.5 - 10.5, the co-dissolution of iron and aluminum is inhibited, and the content of iron and aluminum impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is reduced, thereby improving the purity of the leaching solution containing nickel, cobalt, manganese, and molybdenum;

[0074] (5) In the method of the present invention, by adding an oxidizing agent to oxidize tetravalent molybdenum to hexavalent molybdenum, the leaching rate of molybdenum during the alkali leaching process is improved, thereby improving the final recovery rate of molybdenum;

[0075] (6) In the method of the present invention, by adjusting the pH of the acid leaching solution obtained after acid leaching to 2.0 - 3.0 during selective impurity removal, the precipitation of iron is achieved, and the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is further reduced;

[0076] (7) In the method of the present invention, during selective impurity removal, after adjusting the pH, a deimpurifying agent with a mass of 0.03 - 0.1 wt% of the mass of the acid leaching solution after adjusting the pH is added, and copper and lead impurities are selectively removed, further reducing the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum. Detailed Embodiments

[0077] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0078] Embodiment 1

[0079] This embodiment provides a method for stepwise leaching nickel, cobalt, manganese, and molybdenum, and the method includes:

[0080] (1) Heating the nickel-cobalt-molybdenum waste material in a protective atmosphere at a rate of 3 °C / min to 400 °C, then holding for 60 min, then heating at a rate of 15 °C / min to 600 °C, and then holding for 30 min, and then cooling to 25 °C at a rate of 100 °C / s to obtain the cooled nickel-cobalt-molybdenum waste material;

[0081] (2) Mechanically activating the cooled nickel-cobalt-molybdenum waste material obtained in step (1) by ball milling at a rotation speed of 650 r / min for 10 min to obtain the ball-milled nickel-cobalt-molybdenum waste material; during the ball milling process, the mass ratio of the silicon dioxide grinding aid to the cooled nickel-cobalt-molybdenum waste material is 0.8:100;

[0082] (3) Using an alkali leaching agent containing sodium carbonate, sodium hydroxide, and ammonia water with a molar ratio of 2:0.3:1 to perform alkali leaching on the ball-milled nickel-cobalt-molybdenum waste obtained in step (2) for 2 hours, and then using a reverse osmosis membrane for membrane separation and recovery to obtain a solid material and a leaching solution mainly composed of molybdenum; maintaining the pH at 10 and the temperature at 75°C during the alkali leaching; also adding a sodium persulfate oxidant during the alkali leaching process, and the mass ratio of the sodium persulfate oxidant to the ball-milled nickel-cobalt-molybdenum waste input during alkali leaching is 0.3:100;

[0083] After separating molybdenum from the leaching solution mainly composed of molybdenum using a membrane separation technology, recovered molybdenum and a leaching agent to-be-recovered solution are obtained. Then, a leaching agent with a mass of 12 wt% of the mass of the leaching agent to-be-recovered solution is added to the obtained leaching agent to-be-recovered solution to achieve the recovery of the leaching agent to-be-recovered solution;

[0084] (4) Using sulfuric acid with a concentration of 1.8 mol / L to perform acid leaching on the solid material obtained in step (3) for 4 hours, with the pH being 1 and the temperature being 75°C during the acid leaching to obtain an acid leaching solution;

[0085] (5) After adjusting the pH of the acid leaching solution obtained in step (4) to 2.5, adding sodium sulfide with a mass of 0.05 wt% of the mass of the acid leaching solution after pH adjustment, and filtering to obtain a leaching solution containing nickel, cobalt, manganese, and molybdenum.

[0086] Example 2

[0087] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum, and the method includes:

[0088] (1) Heating the nickel-cobalt-molybdenum waste in a protective atmosphere at a rate of 2°C / min to 320°C, then holding for 80 minutes, then heating at a rate of 20°C / min to 680°C, and then holding for 20 minutes, and then cooling at a rate of 120°C / s to 10°C to obtain the cooled nickel-cobalt-molybdenum waste;

[0089] (2) Mechanically activating the cooled nickel-cobalt-molybdenum waste obtained in step (1) by ball milling at a rotation speed of 500 r / min for 15 minutes to obtain ball-milled nickel-cobalt-molybdenum waste; the mass ratio of the silica grinding aid to the cooled nickel-cobalt-molybdenum waste obtained during the ball milling process is 0.5:100;

[0090] (3) Using an alkali leaching agent containing sodium carbonate, sodium hydroxide, and ammonia water with a molar ratio of 1.4:0.5:1 to perform alkali leaching on the ball-milled nickel-cobalt-molybdenum waste obtained in step (2) for 1 hour, and then using a reverse osmosis membrane for membrane separation and recovery to obtain a solid material and a leaching solution mainly composed of molybdenum; maintaining the pH at 10.5 and the temperature at 60°C during the alkali leaching; also adding a sodium persulfate oxidant during the alkali leaching process, and the mass ratio of the sodium persulfate oxidant to the ball-milled nickel-cobalt-molybdenum waste input during alkali leaching is 0.5:100;

[0091] After separating molybdenum from the leaching solution mainly composed of molybdenum by membrane separation technology, recovered molybdenum and the alkali leaching agent to-be-recovered solution are obtained. Then, an alkali leaching agent with a mass of 15 wt% of the mass of the alkali leaching agent to-be-recovered solution is added to the obtained alkali leaching agent to-be-recovered solution to realize the recovery of the alkali leaching agent to-be-recovered solution;

[0092] (4) Acid-leach the solid material obtained in step (3) with sulfuric acid at a concentration of 1.0 mol / L for 5 h. The pH during the acid leaching is 1.5 and the temperature is 60 °C to obtain an acid leaching solution;

[0093] (5) After adjusting the pH of the acid leaching solution obtained in step (4) to 3.0, sodium sulfide with a mass of 0.1 wt% of the mass of the acid leaching solution after pH adjustment is added, and after filtration, a leaching solution containing nickel, cobalt, manganese, and molybdenum is obtained.

[0094] Example 3

[0095] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum, and the method includes:

[0096] (1) Heat the nickel-cobalt-molybdenum waste material in a protective atmosphere at a rate of 5 °C / min to 480 °C, then hold for 40 min, then heat at a rate of 10 °C / min to 520 °C, then hold for 40 min, and then cool at a rate of 80 °C / s to 50 °C to obtain the cooled nickel-cobalt-molybdenum waste material;

[0097] (2) Mechanically activate the cooled nickel-cobalt-molybdenum waste material obtained in step (1) by ball milling at a rotation speed of 800 r / min for 5 min to obtain the ball-milled nickel-cobalt-molybdenum waste material; the mass ratio of the silicon dioxide grinding aid to the cooled nickel-cobalt-molybdenum waste material during the ball milling is 1:100;

[0098] (3) Alkali-leach the ball-milled nickel-cobalt-molybdenum waste material obtained in step (2) with an alkali leaching agent including sodium carbonate, sodium hydroxide, and ammonia water with a molar ratio of 2.5:0.1:1 for 3 h, and then perform membrane separation and recovery using a filter membrane to obtain a solid material and a leaching solution mainly composed of molybdenum; the pH is maintained at 9.5 and the temperature is 90 °C during the alkali leaching; a sodium persulfate oxidant is also added during the alkali leaching process, and the mass ratio of the sodium persulfate oxidant to the ball-milled nickel-cobalt-molybdenum waste material input during the alkali leaching is 0.1:100;

[0099] After separating molybdenum from the leaching solution mainly composed of molybdenum by membrane separation technology, recovered molybdenum and the alkali leaching agent to-be-recovered solution are obtained. Then, an alkali leaching agent with a mass of 8 wt% of the mass of the alkali leaching agent to-be-recovered solution is added to the obtained alkali leaching agent to-be-recovered solution to realize the recovery of the alkali leaching agent to-be-recovered solution;

[0100] (4) Leach the solid material obtained in step (3) with sulfuric acid at a concentration of 2.5 mol / L for 3 h, with the pH during leaching being 0.5 and the temperature being 90 °C to obtain a leaching solution.

[0101] (5) After adjusting the pH of the leaching solution obtained in step (4) to 2.0, add sodium sulfide at 0.03 wt% of the mass of the leaching solution after pH adjustment, and filter to obtain a leaching solution containing nickel, cobalt, manganese, and molybdenum.

[0102] Example 4

[0103] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Except for omitting the step of heating to 400 °C at a rate of 3 °C / min and holding for 60 min in step (1), that is, directly heating to 600 °C at a rate of 15 °C / min and holding for 30 min and then cooling, the rest are the same as in Example 1.

[0104] Example 5

[0105] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Except for omitting the step of heating to 600 °C at a rate of 15 °C / min and holding for 30 min in step (1), that is, heating to 400 °C at a rate of 3 °C / min and holding for 60 min, and then directly cooling, the rest are the same as in Example 1.

[0106] Example 6

[0107] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Except for omitting step (2), that is, directly subjecting the nickel-cobalt-molybdenum waste after cooling to alkaline leaching, the rest are the same as in Example 1.

[0108] Example 7

[0109] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Except for maintaining the pH at 8.5 during the alkaline leaching in step (3), the rest are the same as in Example 1.

[0110] Example 8

[0111] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Except for maintaining the pH at 11.5 during the alkaline leaching in step (3), the rest are the same as in Example 1.

[0112] Example 9

[0113] This example provides a method for stepwise leaching of nickel, cobalt, manganese, and molybdenum. Except for omitting the sodium persulfate oxidant additionally added during the alkaline leaching process in step (3), the rest are the same as in Example 1.

[0114] Example 10

[0115] This embodiment provides a method for stepwise leaching of nickel, cobalt, manganese and molybdenum. Except that in step (5), the pH of the obtained acid leaching solution is adjusted to 1.5, the rest are the same as in Embodiment 1.

[0116] Embodiment 11

[0117] This embodiment provides a method for stepwise leaching of nickel, cobalt, manganese and molybdenum. Except that in step (5), the pH of the obtained acid leaching solution is adjusted to 4.0, the rest are the same as in Embodiment 1.

[0118] Embodiment 12

[0119] This embodiment provides a method for stepwise leaching of nickel, cobalt, manganese and molybdenum. Except that in step (5), the mass of sodium sulfide added is 0.01% of the mass of the acid leaching solution after pH adjustment, the rest are the same as in Embodiment 1.

[0120] Embodiment 13

[0121] This embodiment provides a method for stepwise leaching of nickel, cobalt, manganese and molybdenum. Except that in step (5), the mass of sodium sulfide added is 0.2% of the mass of the acid leaching solution after pH adjustment, the rest are the same as in Embodiment 1.

[0122] Comparative Example 1

[0123] This comparative example provides a method for stepwise leaching of nickel, cobalt, manganese and molybdenum. Except that in step (1), the cooling rate is 60 °C / s, the rest are the same as in Embodiment 1.

[0124] Comparative Example 2

[0125] This comparative example provides a method for stepwise leaching of nickel, cobalt, manganese and molybdenum. Except that in step (1), the cooling rate is 150 °C / s, the rest are the same as in Embodiment 1.

[0126] Using the methods for stepwise leaching of nickel, cobalt, manganese and molybdenum provided in the above embodiments and comparative examples, nickel, cobalt, manganese and molybdenum in nickel-cobalt-molybdenum waste (with a mass of 1000 g, and the content of each element in the nickel-cobalt-molybdenum waste, i.e., the mass fraction, is shown in Table 1) are leached. Molybdenum is recovered in step (3), and a leaching solution containing nickel, cobalt, manganese and molybdenum is obtained in step (5); an electronic balance is used to test the mass of the obtained recovered molybdenum to obtain the mass of the recovered molybdenum; an inductively coupled plasma spectrometer is used to test the composition of the obtained leaching solution containing nickel, cobalt, manganese and molybdenum, and the content (mass concentration) of each element in the obtained leaching solution containing nickel, cobalt, manganese and molybdenum is shown in Table 2;

[0127] Based on the data in Table 1, the mass of recycled molybdenum obtained from nickel-cobalt-molybdenum waste by weighing, and the data in Table 2, the recovery rates of nickel, cobalt, manganese, and molybdenum are calculated. The calculated recovery rates of nickel, cobalt, manganese, and molybdenum (when calculating the recovery rate of molybdenum, the mass of molybdenum is the sum of the mass of recycled molybdenum and the mass of molybdenum in the leaching solution containing nickel, cobalt, manganese, and molybdenum) are shown in Table 3.

[0128] Table 1

[0129]

[0130] Table 2

[0131]

[0132]

[0133] Table 3

[0134]

[0135]

[0136] It can be seen from Tables 1 to 3 that:

[0137] (1) Using the methods provided in Examples 1 to 3 to perform stepwise leaching of nickel, cobalt, manganese, and molybdenum from nickel-cobalt-molybdenum waste, the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is low, and the recovery rates of nickel, cobalt, manganese, and molybdenum are high;

[0138] (2) By comparing Example 1 with Examples 4 and 5, it can be seen that in the heat treatment of the present invention, volatile impurities in the waste are removed through the first heat preservation, and the leaching activity of the waste is enhanced through the second heat preservation, thereby reducing the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum and increasing the recovery rates of nickel, cobalt, manganese, and molybdenum;

[0139] (3) By comparing Example 1 with Example 6, it can be seen that in the method of the present invention, through mechanical activation of the nickel-cobalt-manganese-molybdenum waste obtained after cooling, defect sites are formed on the surface of the nickel-cobalt-manganese-molybdenum waste obtained after cooling, thereby further increasing the leaching rates of nickel, cobalt, manganese, and molybdenum in the acid leaching and alkali leaching processes, and thus increasing the recovery rates of nickel, cobalt, manganese, and molybdenum;

[0140] (4) By comparing Example 1 with Examples 7 and 8, it can be seen that in the method of the present invention, by controlling the pH to be stable at 9.5 - 10.5 during the alkali leaching process, the co-dissolution of iron and aluminum is inhibited, and the content of iron and aluminum impurities in the finally obtained leaching solution containing nickel, cobalt, manganese, and molybdenum is reduced, thereby increasing the purity of the leaching solution containing nickel, cobalt, manganese, and molybdenum;

[0141] (5) It can be seen from the comparison between Example 1 and Example 9 that in the method of the present invention, by adding an oxidant to oxidize tetravalent molybdenum to hexavalent molybdenum, the leaching rate of molybdenum in the alkali leaching process is improved, thereby improving the final molybdenum recovery rate;

[0142] (6) It can be seen from the comparison between Example 1 and Examples 10 and 11 that in the method of the present invention, by adjusting the pH of the acid leaching solution obtained after acid leaching to 2.0 - 3.0 in the selective impurity removal, the precipitation of iron is achieved, and the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese and molybdenum is further reduced;

[0143] (7) It can be seen from the comparison between Example 1 and Examples 12 and 13 that in the method of the present invention, in the selective impurity removal, by adding an impurity removal agent with a mass of 0.03 - 0.1 wt% of the mass of the acid leaching solution after adjusting the pH after adjusting the pH, copper and lead impurities are selectively removed, and the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese and molybdenum is further reduced;

[0144] (8) It can be seen from the comparison between Example 1 and Comparative Examples 1 and 2 that in the preparation method of the present invention, volatile impurities in the nickel, cobalt, manganese and molybdenum waste are removed by heat treatment, and the leaching activity of the nickel, cobalt, manganese and molybdenum waste is improved. By rapidly cooling, microcracks of the nickel, cobalt, manganese and molybdenum waste are increased. Combined with alkali leaching and acid leaching, not only the leaching rate in the alkali leaching and acid leaching processes is improved, but also the leaching effect is improved, so that the content of impurities in the finally obtained leaching solution containing nickel, cobalt, manganese and molybdenum is low, and the recovery rate of nickel, cobalt, manganese and molybdenum is high; In addition, the steps of the preparation method are simple and the requirements are low, so it also has the advantages of simple recovery process and low recovery cost.

[0145] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for leaching nickel, cobalt, manganese and molybdenum in steps, characterized in that: The method comprises: The nickel, cobalt, manganese and molybdenum waste is heat treated, cooled, and then alkali leached and acid leached in sequence to obtain a leaching solution containing nickel, cobalt, manganese and molybdenum; The cooling rate is 80-120°C / s.

2. The method according to claim 1, characterized in that The heat treatment comprises: subjecting the nickel, cobalt, manganese and molybdenum waste materials to a first heating, a first heat preservation, a second heating and a second heat preservation in sequence in a protective atmosphere; Preferably, the first heating rate is 2-5°C / min, and the end temperature is 320-480°C; Preferably, the first insulation time is 40 to 80 minutes; Preferably, the second heating rate is 10-20°C / min, and the end temperature is 520-680°C; Preferably, the second insulation time is 20 to 40 minutes; Preferably, the terminal temperature of the cooling is 10-50°C.

3. The method according to claim 1 or 2, characterized in that: The method further comprises mechanical activation between the cooling and the pickling; Preferably, the mechanical activation method includes ball milling, and the mass ratio of the grinding aid to the nickel-cobalt-manganese-molybdenum waste obtained after cooling during the ball milling process is (0.5-1):100, the rotation speed of the ball mill is 500-800 r / min, and the time is 5-15 min.

4. The method according to any one of claims 1 to 3, characterized in that: The alkaline leaching agent used in the alkaline leaching includes sodium carbonate, sodium hydroxide and ammonia water in a molar ratio of (1.4-2.5):(0.1-0.5):1; Preferably, during the alkaline leaching, the pH is maintained at 9.5 to 10.5, the temperature is 60 to 90° C., and the time is 1 to 3 hours; Preferably, an oxidant is also added during the alkali leaching process, and the mass ratio of the oxidant to the material to be treated added during the alkali leaching process is (0.1-0.5):

100.

5. The method according to any one of claims 1 to 4, characterized in that: The method further comprises membrane separation and recovery between the alkaline leaching and the acid leaching, and after the membrane separation and recovery, solid materials and a leaching solution whose main component is molybdenum are obtained.

6. The method according to claim 5, characterized in that The method further comprises: recovering molybdenum from the leaching solution whose main component is molybdenum to obtain recovered molybdenum and an alkali leaching agent to be recovered solution, and then recovering the alkali leaching agent from the alkali leaching agent to be recovered solution; Preferably, the molybdenum recovery method comprises: using membrane separation technology to separate molybdenum from a leachate whose main component is molybdenum, to obtain recovered molybdenum and an alkaline leaching agent to be recovered liquid; Preferably, the alkali leaching agent recovery comprises: adding alkali leaching agent in an amount of 8 to 15 wt % of the mass of the alkali leaching agent to be recovered into the alkali leaching agent to be recovered liquid.

7. The method according to any one of claims 1 to 6, characterized in that: The acid leaching agent used in the acid leaching includes sulfuric acid, the pH value during the acid leaching is 0.5-1.5, the temperature is 60-90° C., and the time is 3-5 hours.

8. The method according to any one of claims 1 to 7, characterized in that: The method also includes selective impurity removal after the acid leaching; Preferably, the selective impurity removal comprises: adjusting the pH of the acid leaching solution obtained after acid leaching to 2.0-3.0, adding an impurity remover in an amount of 0.03-0.1% of the mass of the acid leaching solution after pH adjustment, to obtain a leachate containing nickel, cobalt, manganese and molybdenum; Preferably, the method further comprises filtering after the selective impurity removal.

9. The method according to any one of claims 1 to 8, characterized in that: The method comprises: (1) heating the nickel-cobalt-molybdenum waste material to 320-480° C. at a rate of 2-5° C. / min in a protective atmosphere, then keeping the temperature for 40-80 min, then heating the waste material to 520-680° C. at a rate of 10-20° C. / min, then keeping the temperature for 20-40 min, and then cooling the waste material to 10-50° C. at a rate of 80-120° C. / s to obtain cooled nickel-cobalt-molybdenum waste material; (2) mechanically activating the nickel-cobalt-molybdenum waste after cooling obtained in step (1) by ball milling at a rotation speed of 500 to 800 r / min and a time of 5 to 15 min to obtain nickel-cobalt-molybdenum waste after ball milling; the mass ratio of the grinding aid to the nickel-cobalt-molybdenum waste after cooling obtained in the ball milling process is (0.5 to 1):100; (3) alkali leaching the ball-milled nickel-cobalt-molybdenum waste obtained in step (2) for 1 to 3 hours with an alkali leaching agent comprising sodium carbonate, sodium hydroxide and ammonia water in a molar ratio of (1.4 to 2.5):(0.1-0.5):1, and then performing membrane separation and recovery to obtain a solid material and a leachate whose main component is molybdenum; the pH value is maintained at 9.5 to 10.5 and the temperature is maintained at 60 to 90° C. during the alkali leaching; sodium persulfate oxidant is also added during the alkali leaching, and the mass ratio of the sodium persulfate oxidant to the ball-milled nickel-cobalt-molybdenum waste added during the alkali leaching is (0.1 to 0.5):100; After the obtained leaching solution whose main component is molybdenum is subjected to molybdenum recovery, the recovered molybdenum and the alkali leaching agent to be recovered solution are obtained, and then the alkali leaching agent whose mass is 8 to 15 wt % of the mass of the alkali leaching agent to be recovered solution is added to the obtained alkali leaching agent to be recovered solution, so as to achieve the recovery of the alkali leaching agent to be recovered solution; (4) acid leaching the solid material obtained in step (3) for 3 to 5 hours with sulfuric acid having a concentration of 1.0 to 2.5 mol / L, wherein the pH value during the acid leaching is 0.5 to 1.5 and the temperature is 60 to 90° C., to obtain an acid leaching solution; (5) After the pH of the acid leaching solution obtained in step (4) is adjusted to 2.0-3.0, sodium sulfide is added in an amount of 0.03-0.1% of the mass of the acid leaching solution after the pH adjustment, and a leaching solution containing nickel, cobalt, manganese and molybdenum is obtained after filtering.

10. A nickel-cobalt-manganese-molybdenum raw material, characterized in that: The nickel-cobalt-manganese-molybdenum raw material is obtained by the method described in any one of claims 1 to 9.

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