A method for preparing battery-grade nickel sulfate using nickel cobalt hydroxide

Abstract

The invention relates to a method for preparing battery-grade nickel sulfate by using nickel cobalt hydroxide. The method comprises the following steps: slurrying nickel cobalt hydroxide and then pre-leaching to obtain a pre-leaching solution; performing a first solid-liquid separation after the obtained pre-leaching solution is subjected to a first-stage dissolution to obtain an insoluble slag and a first-stage dissolving solution; slurrying the insoluble slag and performing a second-stage dissolution to obtain a second-stage dissolving solution; the reducing agent used in the second-stage dissolution is ferrous sulfate; using high-valent manganese slag as an oxidant to oxidize the dissolving solution to obtain an oxidized solution; then sequentially performing iron precipitation and silicon removal, a second solid-liquid separation, pH adjustment, extraction, oil and phosphorus removal, and a third solid-liquid separation to obtain battery-grade nickel sulfate; the high-valent manganese slag is obtained by post-treating the copper-manganese solution obtained by extraction; the method can shorten the leaching time, improve the leaching efficiency, and can also reduce the use of hazardous chemicals, and avoid the generation of sulfur dioxide and the use of sodium chlorate from the source, thereby reducing safety and environmental risks and realizing safe and environmentally friendly production from the source.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy and relates to a method of utilizing nickel cobalt hydroxide, and in particular to a method of preparing battery-grade nickel sulfate by utilizing nickel cobalt hydroxide. Background Art

[0002] As the resources of sulfide nickel ore are becoming increasingly depleted, laterite nickel ore has become the main resource of nickel raw materials due to its large reserves and easy mining. Nickel cobalt hydroxide raw materials produced by the transformation of laterite nickel ore are gradually becoming the main raw materials for nickel salt production enterprises to produce nickel salt products because their prices are lower than those of nickel raw materials produced by sulfide nickel ore.

[0003] The production of battery-grade nickel sulfate using nickel cobalt hydroxide mostly adopts hydrometallurgical processes, and its procedures generally include sulfuric acid leaching, neutralization and iron and aluminum removal, extraction and impurity removal, nickel and cobalt separation, etc. Due to the complex composition of nickel cobalt hydroxide and the extremely strict requirements of battery-grade nickel sulfate on impurities, hazardous chemicals are often required in the production process, or there is a problem of low production efficiency.

[0004] For example, CN111455174A discloses a method for preparing battery-grade nickel sulfate and cobalt sulfate from mixed nickel and cobalt hydroxide. It uses sulfuric acid to leach the mixed nickel and cobalt hydroxide, and then uses a nickel / cobalt / manganese-based neutralizer to remove iron and aluminum in the solution. Liquid-solid separation obtains iron removal slag acid dissolution to recover nickel and cobalt, and a precipitant is added to the iron removal liquid to remove calcium and magnesium ions in the system. The liquid after calcium and magnesium removal uses a saponified P204 extractant to remove impurities such as Mn, Zn, and Cu, and the P204 raffinate uses a saponified P507 extractant to separate nickel and cobalt to obtain battery-grade nickel sulfate and cobalt sulfate solutions, which are evaporated and crystallized to obtain the product.

[0005] CN111826523A discloses a method for refining nickel cobalt hydroxide, which comprises slurrying nickel cobalt hydroxide, heating, adding acid solution to adjust pH value, reacting to obtain prepreg slurry; adding acid solution to the prepreg slurry to adjust pH value, adding sulfur dioxide to react, reacting to obtain reducing acid leaching solution; adding alkaline slurry to the reducing acid leaching solution to adjust pH value, introducing oxidizing gas, reacting, filtering by pressure to obtain a first filtrate and a first filter residue; adding alkaline solution to a part of the first filtrate to adjust pH value, reacting to obtain a nickel carbonate solution, filtering by pressure to obtain nickel carbonate and nickel precipitation solution; adding nickel carbonate to a part of the first filtrate to obtain nickel carbonate slurry; aging the remaining first filtrate, fine filtering to obtain a first filtrate and a second filter residue, taking the filtrate for second fine filtering to obtain a nickel sulfate solution.

[0006] CN112210679A discloses a method for preparing nickel sulfate from nickel cobalt hydroxide, wherein the nickel cobalt hydroxide contains impurities of manganese, iron, scandium, aluminum and chromium. The method comprises: S1, subjecting the nickel cobalt hydroxide to reduction acid leaching under the action of sulfuric acid and a reducing agent to obtain a leachate; S2, adding a catalyst, an oxidant and a neutralizing agent to the leachate to simultaneously perform a catalytic oxidation reaction and a neutralization reaction to obtain a first impurity-removing solution; S3, extracting and removing impurities from the first impurity-removing solution, evaporating and crystallizing, and obtaining nickel sulfate.

[0007] Although the above-mentioned prior art can prepare battery-grade nickel sulfate using nickel cobalt hydroxide, the following problems are generally present: insoluble slag is added during the dissolution process to reduce pyrosulfate, and the amount of pyrosulfate and sulfuric acid added is large, the dissolution rate is slow, affecting the leaching efficiency of the entire process, and a large amount of sulfur dioxide gas is also generated; in addition, a large amount of acid-insoluble slag is generated during the dissolution process, and this part of the acid-insoluble slag that cannot be completely reduced enters the iron slag, which will affect the difficulty of handling the iron slag, increase the amount of slag washing water, and cause water expansion; and the acid-insoluble slag is a high-priced cobalt-nickel slag such as hydroxy nickel and hydroxy cobalt, and this part of cobalt and nickel enters the slag, causing the loss of nickel and cobalt; in addition, the oxidant used in the conventional prior art is a hazardous chemical such as sodium chlorate or hydrogen peroxide, and the cost of storage and use is relatively high.

[0008] Therefore, in view of the defects of the prior art, it is necessary to provide a method for preparing battery-grade nickel sulfate using nickel cobalt hydroxide. Summary of the invention

[0009] The object of the present invention is to provide a method for preparing battery-grade nickel sulfate by using nickel cobalt hydroxide, wherein the method can shorten the leaching time and improve the leaching efficiency; moreover, the method can avoid the generation of sulfur dioxide and the use of sodium chlorate from the source, thereby reducing the safety risk; moreover, the method can eliminate the use of additional hazardous chemicals, thereby reducing the safety risk and environmental pressure, improving the working environment quality of operators, and essentially realizing safe and environmentally friendly production.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] The present invention provides a method for preparing battery-grade nickel sulfate by using nickel cobalt hydroxide, the method comprising the following steps:

[0012] (1) Pre-leaching after slurrying nickel cobalt hydroxide to obtain a pre-leaching solution;

[0013] (2) the pre-soak obtained in step (1) is subjected to a first solid-liquid separation after a first dissolution to obtain an insoluble residue and a first dissolving liquid;

[0014] (3) The insoluble slag obtained in step (2) is slurried and dissolved in two stages to obtain a two-stage solution; the reducing agent used in the two-stage dissolution is ferrous sulfate;

[0015] (4) using high-valent manganese slag as an oxidant to oxidize the first dissolving liquid obtained in step (2) to obtain an oxidized liquid; then sequentially performing iron precipitation and silicon removal, a second solid-liquid separation, pH adjustment, extraction, oil and phosphorus removal, and a third solid-liquid separation to obtain battery-grade nickel sulfate;

[0016] The high-valent manganese slag in step (4) is obtained by treating the copper-manganese liquid obtained by extraction;

[0017] Step (3) and step (4) are performed in no particular order.

[0018] The method provided by the present invention adopts a technical solution of staged leaching, shortens the leaching time, and improves the leaching efficiency. In addition, the method provided by the present invention adopts ferrous sulfate as a reducing agent during the second-stage dissolution, avoids the generation of sulfur dioxide from the source, and reduces safety risks and environmental risks; in addition, the copper-manganese liquid generated during the extraction process is used as a raw material to prepare high-priced manganese slag, avoiding the use of sodium chlorate, also reducing safety risks, and does not require the purchase of oxidants, saving production costs.

[0019] The "high-valent manganese slag" mentioned in the present invention refers to the manganese slag that can oxidize ferrous sulfate formed by the oxidation of manganese hydroxide, and its main component is MnO(OH).

[0020] Preferably, the solid-to-liquid ratio of the pulping in step (1) is 1:(3-5), for example, it can be 1:3, 1:3.5, 1:4, 1:4.5 or 1:5 but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable. The unit of the solid-to-liquid ratio is g / L.

[0021] Exemplarily, the pre-leaching in step (1) of the present invention is carried out using sulfuric acid with a concentration of 90 wt % or more.

[0022] Preferably, the pre-leaching temperature in step (1) is 70-80°C, for example, 70°C, 72°C, 75°C, 78°C or 80°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the pH value of the pre-leaching in step (1) is 3-4, for example, 3, 3.2, 3.5, 3.8 or 4, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Exemplarily, the dissolution in step (2) is carried out using sulfuric acid having a concentration of 90 wt % or more.

[0025] Preferably, the temperature of the dissolution in step (2) is 70-80°C, for example, 70°C, 72°C, 75°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the pH value of the dissolution in step (2) is 1-1.5, for example, 1, 1.2 or 1.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] The main components of the insoluble slag obtained in step (2) of the present invention are hydroxycobalt and hydroxynickel.

[0028] Preferably, the slurrying in step (3) is carried out using sulfuric acid, and the solid-liquid ratio of the slurry is (1-2):1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.8:1 or 2:1, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The unit of the solid-liquid ratio is g / L.

[0029] In the slurrying of step (3) of the present invention, water is first used as the base liquid, and then the insoluble slag and sulfuric acid are added in sequence. The solid-liquid ratio of the slurrying refers to the solid-liquid ratio of the insoluble slag to the sulfuric acid.

[0030] The mass of the water is generally 1-2 times the mass of the insoluble slag, and the present invention does not make too many restrictions here, as long as the mass concentration of sulfuric acid during slurrying meets the process requirements.

[0031] Preferably, during the slurrying in step (3), the mass concentration of sulfuric acid is ≥35 g / L, for example, it can be 35 g / L, 40 g / L, 50 g / L, 60 g / L, 80 g / L or 100 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the temperature of the second stage dissolution in step (3) is 70-80°C, for example, 70°C, 72°C, 75°C, 78°C or 80°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the time for the second dissolution in step (3) is ≤30 min, for example, it can be 10 min, 15 min, 20 min, 25 min or 30 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] The reducing agent ferrous sulfate is added in the two-stage dissolution process of the present invention, and the reduction end point is that the suspension is clear and bright without insoluble impurities.

[0035] The main components of the insoluble slag obtained by the one-stage dissolution of the present invention are hydroxycobalt and hydroxynickel, which belong to high-valent cobalt and nickel. The conventional production process is reduced in an environment where the slurry pH is 1-1.5. This condition requires the addition of more reducing agents and takes a long time. 3 For example, the conventional process requires more than 4 hours of reduction time, and cannot achieve complete reduction, which is not conducive to continuous and stable production. If the acidity of the slurry is simply adjusted, a large amount of acid will be consumed, which is not conducive to subsequent treatment.

[0036] The present invention adopts a technical scheme of one-stage dissolution, first solid-liquid separation and two-stage dissolution, and reacts hydroxycobalt and hydroxynickel under medium-high acidity conditions, thereby saving the amount of added reducing agent and greatly shortening the reaction time, which is conducive to promoting continuous and stable production and greatly saving time cost and reagent cost.

[0037] The reducing agent used in the second-stage dissolution of the present invention is ferrous sulfate. Conventional reducing agents in this field include sodium pyrosulfite, sodium sulfite, sulfur dioxide, sodium sulfide or hydrogen peroxide. The use of sodium pyrosulfite, sodium sulfite and sulfur dioxide will inevitably produce sulfur dioxide, which has a strong irritating taste; sodium sulfide will generate highly toxic hydrogen sulfide under acidic conditions, and the pH value needs to be adjusted to above 4 before it can be used normally; hydrogen peroxide will produce bubbles, which is easy to cause bubbling, which is not conducive to control. The use of ferrous sulfate in the present application avoids the generation of sulfur dioxide, eliminating pollution sources and dangerous sources from the source; moreover, the present invention uses ferrous sulfate as a reducing agent in the second-stage dissolution, which is equivalent to supplementing iron at the front end of iron precipitation and silicon removal, saving the amount of trivalent iron supplemented later.

[0038] In the present invention, the mass of the reducing agent ferrous sulfate used in the second-stage dissolution is 10-30% of the mass of the insoluble slag, for example, it can be 10%, 15%, 20%, 25% or 30%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the method for preparing the high-valent manganese slag in step (4) comprises the following steps:

[0040] The pH value of the copper-manganese solution is adjusted to 6-6.5; after filtering, the pH value is adjusted to 9-9.5 under the condition of introducing oxygen-containing gas, and the high-valent manganese slag is obtained by solid-liquid separation.

[0041] The present invention can remove more than 99% of copper and zinc by adding alkali to adjust the pH value of the copper-manganese solution to 6-6.5; then continue to add alkali to adjust the pH value to 9-9.5 to precipitate manganese. The manganese hydroxide generated during the precipitation process will be quickly oxidized by air to form high-valent manganese slag. The reaction equation of the process is:

[0042] 4Mn(OH)2+O2=4MnO(OH)+2H2O;

[0043] When the present invention uses copper-manganese liquid to prepare high-valent manganese slag, the pH value is first adjusted to 6-6.5, for example, it can be 6, 6.2 or 6.5, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0044] When the copper-manganese solution is used to prepare high-valent manganese slag in the present invention, the pH value adjusted by adding or subtracting is 9-9.5, for example, it can be 9, 9.2 or 9.5, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0045] Exemplarily, the copper-manganese liquid used to prepare the high-valent manganese slag in the present invention is 5-10% of the copper-manganese liquid obtained by extraction, for example, it can be 5%, 6%, 8%, 9% or 10%, and the rest of the copper-manganese liquid can be used to prepare manganese sulfate.

[0046] Preferably, the amount of polyferric sulfate added during the iron precipitation and silicon removal in step (4) is 2-3wt‰ of the volume of the oxidizing liquid, for example, it can be 2wt‰, 2.2wt‰, 2.5wt‰, 2.8wt‰ or 3wt‰, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] Preferably, the pH value of the iron precipitation and silicon removal in step (4) is 4-4.5, for example, it can be 4, 4.2 or 4.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] Preferably, the endpoint value of the pH adjustment in step (4) is 2-2.5, for example, 2, 2.2, 2.4 or 2.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] Preferably, the extraction in step (4) comprises extraction with extractant P204 and extraction with extractant P507 performed sequentially; the stripping solution obtained by extraction with extractant P204 is a copper-manganese solution.

[0050] Preferably, the solid obtained by the second solid-liquid separation in step (4) is washed with water and filtered in sequence;

[0051] Preferably, the pH value of the water washing liquid used for the water washing is 4.5-5, for example, it can be 4, 4.5, 4.6, 4.8 or 5.

[0052] Preferably, the oil and phosphorus removal of the present invention is carried out using yellow iron oxide, and the addition amount of yellow iron oxide is 5-10g / L, for example, it can be 5g / L, 6g / L, 8g / L or 10g / L, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] The invention can absorb the extractant and the solvent oil by removing oil and phosphorus, and can reduce TOC by 50-80% and TP by 45-85%.

[0054] Preferably, the second-stage dissolved liquid in step (3) and / or the filtrate obtained in the second solid-liquid separation in step (4) are recycled for the slurrying in step (1).

[0055] When the second-stage dissolving liquid in step (3) is reused for the slurrying in step (1), the second-stage dissolving liquid of the previous batch will be mixed into the oxidized first-stage dissolving liquid in step (4).

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The method provided by the present invention adopts a technical solution of staged leaching, which shortens the leaching time and improves the leaching efficiency. Moreover, in the second-stage dissolution, the method provided by the present invention adopts ferrous sulfate as a reducing agent, which avoids the generation of sulfur dioxide from the source, and reduces safety risks and environmental pressures. In addition, the copper-manganese liquid generated in the extraction process is used as a raw material to prepare high-price manganese slag, which avoids the use of sodium chlorate, and also reduces safety risks and environmental pressures. The method can prevent the use of additional hazardous chemicals, reduce safety risks and environmental pressures, improve the working environment quality of operators, and essentially realize safe and environmentally friendly production. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The present invention provides a process flow chart for preparing battery-grade nickel sulfate using nickel cobalt hydroxide. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0060] The composition of the nickel cobalt hydroxide treated in the specific embodiment of the present invention is shown in Table 1, wherein the unit of element composition is wt%. The composition of the nickel cobalt hydroxide is only for the purpose of clearly illustrating the technical solution of the present invention and is not regarded as a further limitation of the nickel cobalt hydroxide.

[0061] Table 1

[0062] Co Cu Ni Fe Ca Mg Pb Zn Mn Cd Cr Si 2.94 0.0007 22.39 1.58 0.036 3.76 0.00089 0.24 1.69 0.007 0.00017 2.32

[0063] Example 1

[0064] This embodiment provides a method for preparing battery-grade nickel sulfate using nickel cobalt hydroxide. The process flow chart of the method is as follows: Figure 1 As shown, the following steps are included:

[0065] (1) Pre-leaching nickel cobalt hydroxide pulping to obtain a pre-leaching solution; the pre-leaching is performed using 98 wt % sulfuric acid, the pre-leaching temperature is 75° C., and the pH value is 3.5; the solid-liquid ratio of the pulping is 1:4, and the unit of the solid-liquid ratio is g / L;

[0066] (2) the pre-soak obtained in step (1) is subjected to a first solid-liquid separation after a first dissolution to obtain an insoluble residue and a first dissolution solution; the first dissolution is carried out using 98 wt % sulfuric acid at a temperature of 75° C. and a pH of 1.2; the first solid-liquid separation is filtration;

[0067] (3) The insoluble slag obtained in step (2) is subjected to slurrying and two-stage dissolution to obtain a two-stage solution; the reducing agent used in the two-stage dissolution is ferrous sulfate, and the mass of ferrous sulfate is 20% of the mass of the insoluble slag; the slurrying is carried out using sulfuric acid, the solid-liquid ratio is 1.5:1, the unit of the solid-liquid ratio is g / L, and the sulfuric acid concentration during slurrying is 50g / L;

[0068] The temperature of the second stage dissolution is 75°C and the time is 30 minutes;

[0069] (4) using high-valent manganese slag as an oxidant to oxidize the solution obtained in step (2) to obtain an oxidized solution; then sequentially performing iron precipitation and silicon removal, a second solid-liquid separation, pH adjustment, extraction, oil and phosphorus removal, and filtration to obtain battery-grade nickel sulfate;

[0070] The amount of polyferric sulfate added during the iron precipitation and silicon removal is 2.5‰ of the volume of the oxidation solution, and the pH value is 4.2; the solid obtained by the second solid-liquid separation is washed and filtered in sequence, and the pH value of the water washing liquid used for washing is 4.8; the pH value of the adjustment is adjusted to 2.2 using 98% sulfuric acid; the extraction includes extraction with extractant P204 and extraction with extractant P507 in sequence; the stripping solution obtained by extraction with extractant P204 is a copper-manganese solution; the oil and phosphorus removal is carried out using iron oxide yellow, and the amount of iron oxide yellow added is 8g / L;

[0071] The copper-manganese liquid obtained by extracting the high-valent manganese slag with the extractant P204 in step (4) is treated as follows: sodium hydroxide is added to adjust the pH value of the copper-manganese liquid to 6.2; after filtering, sodium hydroxide is continued to be added under the condition of air to adjust the pH value to 9.2, and high-valent manganese slag is obtained by solid-liquid separation.

[0072] The second-stage dissolved liquid in step (3) and the filtrate obtained in the second solid-liquid separation in step (4) are recycled for the slurrying in step (1).

[0073] Example 2

[0074] This embodiment provides a method for preparing battery-grade nickel sulfate using nickel cobalt hydroxide. The process flow chart of the method is as follows: Figure 1As shown, the following steps are included:

[0075] (1) Pre-leaching nickel cobalt hydroxide pulping to obtain a pre-leaching solution; the pre-leaching is carried out using 98 wt % sulfuric acid, the pre-leaching temperature is 70° C., and the pH value is 3; the solid-liquid ratio of the pulping is 1:3, and the unit of the solid-liquid ratio is g / L;

[0076] (2) the pre-soak obtained in step (1) is subjected to a first solid-liquid separation after a first dissolution to obtain an insoluble residue and a first dissolution liquid; the first dissolution is carried out using 98 wt % sulfuric acid at a temperature of 70° C. and a pH of 1; the first solid-liquid separation is filtration;

[0077] (3) The insoluble slag obtained in step (2) is subjected to slurrying and two-stage dissolution to obtain a two-stage solution; the reducing agent used in the two-stage dissolution is ferrous sulfate, and the mass of ferrous sulfate is 10% of the mass of the insoluble slag; the slurrying is carried out using sulfuric acid, the solid-liquid ratio is 1.1:1, the unit of the solid-liquid ratio is g / L, and the sulfuric acid concentration during slurrying is 60g / L;

[0078] The temperature of the second stage dissolution is 70°C and the time is 30 minutes;

[0079] (4) using high-valent manganese slag as an oxidant to oxidize the solution obtained in step (2) to obtain an oxidized solution; then sequentially performing iron precipitation and silicon removal, a second solid-liquid separation, pH adjustment, extraction, oil and phosphorus removal, and filtration to obtain battery-grade nickel sulfate;

[0080] The amount of polyferric sulfate added during the iron precipitation and silicon removal is 2‰ of the volume of the oxidation liquid, and the pH value is 4; the solid obtained by the second solid-liquid separation is washed and filtered in sequence, and the pH value of the water washing liquid used for washing is 4.5; the pH value of the adjustment is adjusted to 2 using 98% sulfuric acid; the extraction includes extraction with extractant P204 and extraction with extractant P507 in sequence; the stripping solution obtained by extraction with extractant P204 is a copper-manganese solution; the oil and phosphorus removal is carried out using iron oxide yellow, and the amount of iron oxide yellow added is 5g / L;

[0081] The copper-manganese liquid obtained by extracting the high-valent manganese slag with the extractant P204 in step (4) is treated as follows: sodium hydroxide is added to adjust the pH value of the copper-manganese liquid to 6; after filtering, sodium hydroxide is continued to be added under the condition of air to adjust the pH value to 9, and high-valent manganese slag is obtained by solid-liquid separation.

[0082] The second-stage dissolved liquid in step (3) and the filtrate obtained in the second solid-liquid separation in step (4) are recycled for the slurrying in step (1).

[0083] Example 3

[0084] This embodiment provides a method for preparing battery-grade nickel sulfate using nickel cobalt hydroxide. The process flow chart of the method is as follows: Figure 1 As shown, the following steps are included:

[0085] (1) Pre-leaching nickel cobalt hydroxide pulping to obtain a pre-leaching solution; the pre-leaching is carried out using 98 wt % sulfuric acid, the pre-leaching temperature is 80° C., and the pH value is 4; the solid-liquid ratio of the pulping is 1:5, and the unit of the solid-liquid ratio is g / L;

[0086] (2) the pre-soak obtained in step (1) is subjected to a first solid-liquid separation after a first dissolution to obtain an insoluble residue and a first dissolution liquid; the first dissolution is carried out using 98 wt % sulfuric acid at a temperature of 80° C. and a pH of 1.5; the first solid-liquid separation is filtration;

[0087] (3) The insoluble slag obtained in step (2) is subjected to slurrying and two-stage dissolution to obtain a two-stage solution; the reducing agent used in the two-stage dissolution is ferrous sulfate, and the mass of ferrous sulfate is 30% of the mass of the insoluble slag; the slurrying is carried out using sulfuric acid, the solid-liquid ratio is 2:1, the unit of the solid-liquid ratio is g / L, and the sulfuric acid concentration during slurrying is 35g / L;

[0088] The temperature of the second stage dissolution is 80°C and the time is 30 minutes;

[0089] (4) using high-valent manganese slag as an oxidant to oxidize the solution obtained in step (2) to obtain an oxidized solution; then sequentially performing iron precipitation and silicon removal, a second solid-liquid separation, pH adjustment, extraction, oil and phosphorus removal, and filtration to obtain battery-grade nickel sulfate;

[0090] The amount of polyferric sulfate added during the iron precipitation and silicon removal is 3‰ of the volume of the oxidation solution, and the pH value is 4.5; the solid obtained by the second solid-liquid separation is washed and filtered in sequence, and the pH value of the water washing solution used for washing is 5; the pH value of the adjustment is adjusted to 2.5 using 98% sulfuric acid; the extraction includes extraction with extractant P204 and extraction with extractant P507 in sequence; the stripping solution obtained by extraction with extractant P204 is a copper-manganese solution; the oil and phosphorus removal is carried out using iron oxide yellow, and the amount of iron oxide yellow added is 10g / L;

[0091] The copper-manganese liquid obtained by extracting the high-valent manganese slag with the extractant P204 in step (4) is treated to obtain: sodium hydroxide is added to adjust the pH value of the copper-manganese liquid to 6.5; after filtering, sodium hydroxide is continued to be added under the condition of air to adjust the pH value to 9.5, and high-valent manganese slag is obtained by solid-liquid separation.

[0092] The second-stage dissolved liquid in step (3) and the filtrate obtained in the second solid-liquid separation in step (4) are recycled for the slurrying in step (1).

[0093] The composition of the nickel sulfate solution after deoiling and dephosphorization in the embodiment of the present invention is shown in Table 2, and the unit of each element composition is g / L; the standard of battery-grade nickel sulfate is that the concentration of each element satisfies: Ni ≥ 125 g / L, Mg ≤ 0.005 g / L, Ca ≤ 0.005 g / L, Cu ≤ 0.001 g / L, Zn ≤ 0.001 g / L, Fe ≤ 0.001 g / L, Pb ≤ 0.001 g / L, Cd ≤ 0.001 g / L, Cr ≤ 0.002 g / L, Li ≤ 0.002 g / L, Si ≤ 0.005 g / L and total phosphorus (TP) ≤ 0.01 g / L.

[0094] Table 2

[0095]

[0096] The “ND” in Table 2 means that the content is below the detection limit and cannot be detected.

[0097] In summary, the method provided by the present invention adopts a technical scheme of staged leaching, which shortens the leaching time and improves the leaching efficiency; and the method provided by the present invention adopts ferrous sulfate as a reducing agent during the second-stage dissolution, which avoids the generation of sulfur dioxide from the source and reduces safety risks and environmental pressures; in addition, the copper-manganese liquid generated in the extraction process is used as a raw material to prepare high-valent manganese slag, avoiding the use of sodium chlorate, and also reducing safety risks and environmental pressures; the present invention adopts a technical scheme of one-stage dissolution, a first solid-liquid separation and a two-stage dissolution, and reacts hydroxycobalt with hydroxynickel under medium-high acidity conditions, saving the amount of reducing agent added, and the reaction time is greatly shortened, which is conducive to promoting continuous and stable production, and greatly saving time cost and reagent cost; the reducing agent used for the second-stage dissolution of the present invention is ferrous sulfate, and the use of ferrous sulfate avoids the generation of sulfur dioxide, eliminating pollution sources and dangerous sources from the source; and the use of ferrous sulfate as a reducing agent in the second-stage dissolution is equivalent to supplementing iron at the front end of iron precipitation and silicon removal, saving the amount of trivalent iron supplemented later.

[0098] The above description is only a specific implementation mode 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 those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing battery-grade nickel sulfate using nickel cobalt hydroxide, characterized in that: The method comprises the following steps: (1) Pre-leaching after slurrying nickel cobalt hydroxide to obtain a pre-leaching solution; (2) the pre-soak obtained in step (1) is subjected to a first solid-liquid separation after a first dissolution to obtain an insoluble residue and a first dissolving liquid; (3) The insoluble slag obtained in step (2) is slurried and dissolved in two stages to obtain a two-stage solution; the reducing agent used in the two-stage dissolution is ferrous sulfate; (4) using high-valent manganese slag as an oxidant to oxidize the first dissolving liquid obtained in step (2) to obtain an oxidized liquid; then sequentially performing iron precipitation and silicon removal, a second solid-liquid separation, pH adjustment, extraction, oil and phosphorus removal, and a third solid-liquid separation to obtain battery-grade nickel sulfate; The high-valent manganese slag in step (4) is obtained by treating the copper-manganese liquid obtained by extraction; Step (3) and step (4) are performed in no particular order; The second-stage dissolving liquid in step (3) and / or the filtrate obtained in the second solid-liquid separation in step (4) are recycled for pulping in step (1).

2. The method according to claim 1, characterized in that The pre-leaching temperature in step (1) is 70-80°C.

3. The method according to claim 1, characterized in that The pH value of the pre-leaching in step (1) is 3-4.

4. The method according to claim 1, characterized in that: The temperature of the first stage of dissolution in step (2) is 70-80°C.

5. The method according to claim 1, characterized in that The pH value of the dissolution in step (2) is 1-1.

5.

6. The method according to claim 1, characterized in that The slurrying in step (3) is carried out using sulfuric acid, and the solid-liquid ratio of the slurrying is (1-2):1, and the unit of the solid-liquid ratio is g / L.

7. The method according to claim 1, characterized in that During the slurrying in step (3), the mass concentration of sulfuric acid is ≥35 g / L.

8. The method according to claim 1, characterized in that The temperature of the second stage dissolution in step (3) is 70-80°C.

9. The method according to claim 1, characterized in that: The time of the second dissolution in step (3) is ≤30min.

10. The method according to claim 1, characterized in that The method for preparing the high-valent manganese slag in step (4) comprises the following steps: The pH value of the copper-manganese solution is adjusted to 6-6.5; after filtering, the pH value is adjusted to 9-9.5 under the condition of introducing oxygen-containing gas, and the high-valent manganese slag is obtained by solid-liquid separation.

11. The method according to claim 1, characterized in that: In step (4), the amount of polyferric sulfate added during the iron precipitation and silicon removal is 2-3‰ of the volume of the oxidation solution.

12. The method according to claim 1, characterized in that The pH value of the iron precipitation and silicon removal in step (4) is 4-4.

5.

13. The method according to claim 1, characterized in that The endpoint value of the pH value adjustment in step (4) is 2-2.

5.

14. The method according to claim 1, characterized in that The extraction in step (4) includes extraction with extractant P204 and extraction with extractant P507 performed in sequence; the stripping solution obtained by extraction with extractant P204 is a copper-manganese solution.

15. The method according to claim 1, characterized in that Step (4) The solid obtained by the second solid-liquid separation is washed with water and filtered in sequence.

16. The method according to claim 15, characterized in that The pH value of the water washing liquid used for the water washing is 4.5-5.

Images