Preparation method and system of nickel sulfate solution

Abstract

The invention relates to the technical field of hydrometallurgy, and discloses a nickel sulfate solution preparation method and system.The method comprises the steps that a rough nickel sulfate solution is sequentially subjected to heating treatment and solid-liquid separation treatment, and a solution a and impurity removal slag are obtained; the temperature of the heating treatment is 160-210 DEG C; the temperature of the solid-liquid separation treatment is 160-210 DEG C; the crude nickel sulfate solution contains 0.1 to 2 g / L of Fe < 3 + >, 0.1 to 1 g / L of Al < 3 + >, 0.01 to 0.5 g / L of Cr < 3 + >, 7.5 to 16 g / L of Mn < 2 + >, 0.2 to 0.6 g / L of Ca < 2 + > and 0.2 to 5 g / L of Mg < 2 + >. According to the nickel sulfate preparation process provided by the invention, metal impurity ions in the crude nickel sulfate solution can be greatly removed, the reagent consumption is low, calcium ions can be removed, the problem of pipeline structure blockage caused by precipitation of calcium sulfate in a pipeline is effectively reduced, and the process economy and the production efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly relates to a preparation method and system for nickel sulfate solution. Background Art

[0002] With the rapid development of new energy electric vehicles, the demand for nickel sulfate, an important component of power battery raw materials, is increasing continuously. Moreover, during the preparation of nickel sulfate, solutions in the production process are often transported between different processes through pipelines.

[0003] However, the current nickel sulfate preparation process has problems such as serious scaling of solution pipelines, high reagent consumption, and low economy. Summary of the Invention

[0004] The present invention provides a preparation method for nickel sulfate solution, aiming to solve the problems of serious scaling of solution pipelines, high reagent consumption, and low economy in the prior art.

[0005] To achieve the above object, a first aspect of an embodiment of the present invention provides a preparation method for nickel sulfate solution, including: sequentially performing heat treatment and solid-liquid separation treatment on the crude nickel sulfate solution to obtain solution a and impurity removal slag;

[0006] The temperature of the heat treatment is 160 - 210 °C;

[0007] The temperature of the solid-liquid separation treatment is 160 - 210 °C;

[0008] The crude nickel sulfate solution contains 0.1 - 2 g / L of Fe 3+ , 0.1 - 1 g / L of Al 3+ , 0.01 - 0.5 g / L of Cr 3+ , 7.5 - 16 g / L of Mn 2+ , 0.2 - 0.6 g / L of Ca 2+ , 0.2 - 5 g / L of Mg 2+ .

[0009] An embodiment of the present invention utilizes the crude nickel sulfate solution with the above component concentration ranges, combined with high-temperature conditions, to promote Al in the crude nickel sulfate solution 3+ , Cr 3+Impurities such as these form chemical precipitates. At the same time, the solubilities of impurities such as MnSO4, CaSO4, and MgSO4 decrease when heated to 160 - 210 °C, causing them to precipitate after reaching supersaturation, thereby significantly removing metal impurity ions in the crude nickel sulfate solution with less reagent consumption. Metal impurities can be significantly removed without using reagents such as neutralizing agents, ozone, and oxygen, and calcium ions can be removed, effectively reducing the problem of pipeline blockage caused by the precipitation of calcium sulfate in the pipeline and improving production efficiency. Moreover, the nickel sulfate preparation process provided by the present invention can obtain impurity-removing slag with a relatively high manganese sulfate content, enabling it to be directly sold instead of being treated as hazardous waste, thus improving production economy.

[0010] Optionally, the time for the heat treatment is 5 - 120 min.

[0011] Optionally, the manganese sulfate content in the impurity-removing slag is ≥80 wt%.

[0012] Optionally, the iron element content in the solution a is ≤30 mg / L, and the aluminum element content is ≤30 mg / L.

[0013] Optionally, the solid-liquid separation treatment is carried out by filtration; the filter medium used for filtration is an acid-resistant and high-temperature-resistant material.

[0014] Optionally, the filter medium is selected from at least one of polytetrafluoroethylene, glass fiber, carbon fiber, metal fiber, and ceramic fiber.

[0015] Optionally, the metal fiber is selected from at least one of titanium fiber, 904 stainless steel fiber, and Hastelloy fiber.

[0016] Optionally, the crude nickel sulfate solution is prepared by the following method: mixing and leaching nickel hydroxide intermediate product with sulfuric acid to obtain the crude nickel sulfate solution.

[0017] Optionally, the concentration of the sulfuric acid is 12 - 99 wt%.

[0018] Optionally, the mass ratio of the nickel hydroxide intermediate product to the amount of sulfuric acid used is 1:(0.7 - 7.5).

[0019] Optionally, the conditions for the mixing and leaching include: temperature of 60 - 110 °C, and the final pH value of 1.0 - 4.0.

[0020] In some embodiments, the method further includes:

[0021] Perform a first heat exchange treatment on the solution a and the crude nickel sulfate solution, obtaining the heated solution b from the crude nickel sulfate solution and the cooled solution c from the solution a. Concentrate the solution c to obtain solution d;

[0022] Perform the heating treatment on the solution b.

[0023] In some embodiments, the method further includes:

[0024] Perform a second heat exchange treatment on the solution a and solution e, obtaining the heated solution b from the solution e and the cooled solution c from the solution a. Concentrate the solution c to obtain solution d;

[0025] Perform a third heat exchange treatment on the solution d and the crude nickel sulfate solution, obtaining the heated solution e from the crude nickel sulfate solution and the cooled solution f from the solution d;

[0026] Perform the heating treatment on the solution b.

[0027] The second aspect of the embodiments of the present invention provides a preparation system for nickel sulfate solution, which system includes:

[0028] A high-temperature reaction kettle, including a hot medium cavity and a cold medium cavity, both the hot medium cavity and the cold medium cavity are provided with inlets and outlets;

[0029] A filter, including a filter inlet, a filter outlet and a filtering medium;

[0030] A secondary preheating tank, including a hot medium cavity and a cold medium cavity, both the hot medium cavity and the cold medium cavity are provided with inlets and outlets;

[0031] A flash evaporation kettle, including a flash evaporation kettle inlet and a flash evaporation kettle outlet;

[0032] The outlet of the cold medium cavity of the high-temperature reaction kettle is connected to the inlet of the filter, the outlet of the filter is connected to the inlet of the hot medium cavity of the secondary preheating tank, the outlet of the hot medium cavity of the secondary preheating tank is connected to the inlet of the flash evaporation kettle, and the outlet of the cold medium cavity of the secondary preheating tank is connected to the inlet of the cold medium cavity of the high-temperature reaction kettle.

[0033] In some embodiments, a primary preheating tank is further provided downstream of the flash evaporation kettle. The primary preheating tank includes a hot medium cavity and a cold medium cavity, both the hot medium cavity and the cold medium cavity are provided with inlets and outlets;

[0034] The outlet of the cold medium cavity of the high-temperature reactor is connected to the inlet of the filter, the outlet of the filter is connected to the inlet of the hot medium cavity of the secondary preheating tank, the outlet of the hot medium cavity of the secondary preheating tank is connected to the inlet of the flash evaporation tank, the outlet of the flash evaporation tank is connected to the inlet of the hot medium cavity of the primary preheating tank, the outlet of the cold medium cavity of the primary preheating tank is connected to the inlet of the cold medium cavity of the secondary preheating tank, and the outlet of the cold medium cavity of the secondary preheating tank is connected to the inlet of the cold medium cavity of the high-temperature reactor.

[0035] Optionally, the filter is a bag filter, and the filtering medium of the filter is an acid-resistant and high-temperature-resistant material.

[0036] Optionally, the number of the bag filters is not less than 2. Description of the Drawings

[0037] Figure 1 It is a schematic process flow diagram for preparing a nickel sulfate solution according to an optional embodiment of the present invention.

[0038] 100 - high-temperature reactor, 200 - filter, 300 - secondary preheating tank, 400 - flash evaporation tank, 500 - primary preheating tank. Detailed Embodiments

[0039] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present invention, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0040] If there is no special instruction, all the embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0042] Unless otherwise specified, all steps of the present invention can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

[0043] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present invention mean open-ended, and can also be closed-ended. For example, the "comprising" and "including" may mean that other components not listed may also be included, or may only include the components listed.

[0044] Unless otherwise specified, in the present invention, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0045] In some embodiments of the present invention, "natural basis" refers to the natural state (containing water) of the material, and "dry basis" refers to the state of the material after removing water. For example: assuming that in the MHP raw material, the water content is 50.09%, it refers to the water content in the natural basis of the MHP raw material; after drying the MHP raw material, a dry basis is obtained, and the dry basis refers to the mass of the remaining solid after drying. Unless otherwise specified, the content of elements or components in the present invention refers to the content on a dry basis, that is, the content of elements or components after removing water.

[0046] In some embodiments of the present invention, the English abbreviation of nickel hydroxide intermediate product is MHP, also called nickel cobalt hydroxide, which is an intermediate product in nickel smelting and belongs to the intermediate product in hydrometallurgical nickel smelting. Its source can be the process of pressure leaching of laterite nickel ore - magnesium oxide precipitation of nickel. The main elements of the prepared nickel cobalt hydroxide include nickel, cobalt, manganese and magnesium. Among them, nickel, cobalt and manganese mainly exist in the form of hydroxides and oxides. In some laterite nickel ores, copper elements may be contained, and in some nickel cobalt hydroxides, calcium elements from the smelting process may also be contained.

[0047] In some embodiments of the present invention, a first aspect of the embodiments of the present invention provides a method for preparing a nickel sulfate solution, comprising: sequentially performing a heating treatment and a solid-liquid separation treatment on a crude nickel sulfate solution to obtain a solution a and a purification residue;

[0048] The temperature of the heating treatment is 160 - 210 °C;

[0049] The temperature of the solid-liquid separation treatment is 160 - 210 °C;

[0050] The crude nickel sulfate solution contains 0.1 - 2 g / L of Fe 3+ , 0.1 - 1 g / L of Al 3+ , 0.01 - 0.5 g / L of Cr 3+ , 7.5 - 16 g / L of Mn 2+ , 0.2 - 0.6 g / L of Ca 2+ , 0.2 - 5 g / L of Mg 2+ .

[0051] The crude nickel sulfate solution in the embodiments of the present invention contains Fe 3+ , and the concentration of Fe 3+ is 0.1 - 2 g / L, and can be, for example, 0.1 g / L, 0.5 g / L, 1.0 g / L, 1.5 g / L, 2.0 g / L or any value between 0.1 - 2 g / L.

[0052] The crude nickel sulfate solution in the embodiments of the present invention contains Al 3+ , and the concentration of Al 3+ is 0.1 - 1 g / L, and can be, for example, 0.1 g / L, 0.2 g / L, 0.4 g / L, 0.6 g / L, 0.8 g / L, 1 g / L or any value between 0.1 - 1 g / L.

[0053] The crude nickel sulfate solution in the embodiments of the present invention contains Cr 3+ , and the concentration of Cr 3+ is 0.01 - 0.5 g / L, and can be, for example, 0.01 g / L, 0.05 g / L, 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.25 g / L, 0.3 g / L, 0.35 g / L, 0.4 g / L, 0.45 g / L, 0.5 g / L or any value between 0.01 - 0.5 g / L.

[0054] The crude nickel sulfate solution in the embodiments of the present invention contains Mn 2+ , and the concentration of Mn 2+The concentration is 7.5 to 16 g / L, for example, it can be 7.5 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L or any value between 7.5 and 16 g / L.

[0055] In the crude nickel sulfate solution of the embodiment of the present invention, Ca is contained 2+ , and the concentration of Ca 2+ is 0.2 to 0.6 g / L, for example, it can be 0.2 g / L, 0.25 g / L, 0.3 g / L, 0.35 g / L, 0.4 g / L, 0.45 g / L, 0.5 g / L, 0.55 g / L, 0.6 g / L or any value between 0.2 and 0.6 g / L.

[0056] In the crude nickel sulfate solution of the embodiment of the present invention, Mg is contained 2+ , and the concentration of Mg 2+ is 0.2 to 5 g / L, for example, it can be 0.2 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L or any value between 0.2 and 5 g / L.

[0057] In the embodiment of the present invention, the crude nickel sulfate solution is heat-treated under specific high-temperature conditions to promote the formation of chemical precipitates of impurities such as Al 3+ , Cr 3+ in the crude nickel sulfate solution. And by utilizing the solubility changes of impurities such as MnSO4, CaSO4, and MgSO4, solid-liquid separation treatment is carried out under high-temperature conditions, significantly reducing the generation of impurity removal slag, reducing the consumption of extraction impurity removal reagents in the subsequent stage, and effectively reducing the problem of pipeline structure blockage caused by the precipitation of calcium sulfate in the pipeline. This not only reduces the production cost, improves the production efficiency, but also can reduce environmental pollution.

[0058] In some embodiments, the heat treatment is carried out in a non-oxidizing atmosphere. It can be understood that the non-oxidizing atmosphere can be an air atmosphere or one of inert atmospheres such as a nitrogen atmosphere or an argon atmosphere.

[0059] Optionally, the time of the heat treatment is 5 to 120 min, for example, it can be 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min or any value between 5 and 120 min.

[0060] Optionally, the manganese sulfate content in the impurity removal residue is ≥80 wt%, for example, it can be 82 wt%, 84 wt%, 86 wt%, 88 wt%, 90 wt%, 92 wt%, 94 wt%, 96 wt%, 98 wt% or any value ≥80 wt%. The manganese sulfate content in the impurity removal residue obtained by the embodiments of the present invention is high, and it can be directly sold or further purified to obtain a manganese sulfate product, effectively reducing the generation of hazardous waste residues in the subsequent treatment process.

[0061] Optionally, the iron element content in solution a is ≤30 mg / L, for example, it can be 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L or any value ≤30 mg / L; the aluminum element content is ≤30 mg / L, for example, it can be 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L or any value ≤30 mg / L. Through impurity removal at high temperature, the embodiments of the present invention can reduce the contents of iron element and aluminum element in the obtained solution a to meet the requirements for Fe and Al in the extraction during the production of battery-grade nickel sulfate.

[0062] Optionally, a filtration method is adopted for solid-liquid separation treatment; the filtration medium used for filtration is an acid-resistant and high-temperature-resistant material.

[0063] Optionally, the filtration medium is selected from at least one of polytetrafluoroethylene, glass fiber, carbon fiber, metal fiber, and ceramic fiber.

[0064] Optionally, the metal fiber is selected from at least one of titanium fiber, 904 stainless steel fiber, and Hastelloy fiber.

[0065] Optionally, the crude nickel sulfate solution is prepared by the following method: mixing and leaching nickel hydroxide intermediate product with sulfuric acid to obtain the crude nickel sulfate solution.

[0066] In some embodiments, when the nickel hydroxide intermediate product is mixed and leached with sulfuric acid, no additional reducing agent is added. This is beneficial to controlling the metal ion concentration in the obtained crude nickel sulfate solution within the above range, thus facilitating the improvement of process economy through heat treatment.

[0067] In the embodiments of the present invention, the nickel hydroxide intermediate product is leached with sulfuric acid without adding a reducing agent, so that the oxidized manganese (such as trivalent, tetravalent and other high-valent oxides or hydroxides of manganese) in the nickel hydroxide intermediate product is not leached as much as possible, and at the same time, iron exists as trivalent iron ions as much as possible, which is beneficial to promoting iron precipitation during heat treatment. The leaching residue obtained by mixing and leaching is recovered in the form of crude manganese oxide after pickling.

[0068] Optionally, the concentration of sulfuric acid is 12-99 wt%, for example, it can be 12 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 99 wt% or any value between 12-99 wt%.

[0069] Optionally, the mass ratio of the nickel hydroxide intermediate product to the sulfuric acid dosage is 1:(0.7-7.5), for example, it can be 1:0.7, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5 or any ratio between 1:(0.7-7.5). Exemplarily, when the mass ratio of the nickel hydroxide intermediate product to the sulfuric acid dosage is 1:0.7, it means the mass ratio of the nickel hydroxide intermediate product to the sulfuric acid with a certain concentration is 1:0.7.

[0070] Optionally, the conditions for the mixed leaching include: the temperature is 60-110 °C, for example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C or any value between 60-110 °C. The above temperature can be reached by the natural heat release of the reaction or by the heat release when concentrated sulfuric acid meets water; the end point pH value is 1.0-4.0, for example, it can be 1, 1.5, 2, 2.5, 3, 3.5, 4 or any value between 1.0-4.0.

[0071] In the embodiment of the present invention, the time for the mixed leaching can be optionally 0.5-5 h, for example, it can be 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h or any value between 0.5-5 h; so that the end point pH value of the mixed leaching is within the range required by the specific embodiment of the present invention.

[0072] In some embodiments, the method further includes:

[0073] Performing a first heat exchange treatment on the solution a and the crude nickel sulfate solution to obtain a heated solution b from the crude nickel sulfate solution and a cooled solution c from the solution a, and concentrating the solution c to obtain a solution d;

[0074] Performing the heating treatment on the solution b.

[0075] In some embodiments, the method further includes:

[0076] Performing a second heat exchange treatment on the solution a and the solution e to obtain a heated solution b from the solution e and a cooled solution c from the solution a, and concentrating the solution c to obtain a solution d;

[0077] Perform a third heat exchange treatment on the solution d and the crude nickel sulfate solution to obtain a heated solution e from the crude nickel sulfate solution and a cooled solution f from the solution d;

[0078] Perform the heating treatment on the solution b.

[0079] Optionally, perform the concentration treatment by flash evaporation. After flash evaporation, the solution c is concentrated into a solution d with a higher nickel concentration, thereby improving the subsequent impurity removal efficiency.

[0080] In the embodiment of the present invention, the crude nickel sulfate solution to be treated is heat-exchanged with the relatively high-temperature solution a and / or the solution d obtained after flash evaporation and concentration, so that the temperature is increased, and then the heating treatment is performed, which can realize the hierarchical utilization of thermal energy, further reduce the energy consumption of the entire process, and improve the production economy.

[0081] According to a specific embodiment of the present invention, the preparation method of the nickel sulfate solution is carried out in the following way: heating treatment of the crude nickel sulfate solution → solid-liquid separation treatment → second heat exchange treatment → flash evaporation and concentration treatment → third heat exchange treatment. After the third heat exchange treatment, the solution temperature is relatively low, and the flash evaporation and concentration effect is limited. Therefore, in this solution, it is preferably to perform the flash evaporation and concentration treatment after the second heat exchange treatment, and then perform the third heat exchange treatment, which can increase the solution temperature after the second heat exchange treatment. The temperature of the preheated liquid can reach above 100 °C, saving the heating time in the high-temperature impurity removal process and obtaining a higher thermal utilization rate.

[0082] In some embodiments of the present invention, the preparation method of the nickel sulfate solution of the present invention further includes performing an extraction process and a crystallization process on the solution f to obtain a nickel sulfate product.

[0083] The present invention does not particularly limit the specific operation methods of the extraction process and the crystallization process. Those skilled in the art can select according to the known technical means in the art. Exemplarily, P204 extractant is used for extraction. The present invention will not elaborate herein, and those skilled in the art should not understand it as a limitation of the present invention.

[0084] Adopting the technical solution of the specific embodiment of the present invention can remove as many impurity ions such as 3+ Fe, 3+ Al, 3+ Cr, 2+ Mn, 2+ Ca, 2+ Mg, etc. in the crude nickel sulfate solution as possible, realizing a reduction of the acid consumption of the system by 1% - 3%, and effectively alleviating problems such as pipeline blockage, calcium slag deposition, heavy extraction load, and high crystallization energy consumption in the subsequent process.

[0085] As described above, the second aspect of the embodiment of the present invention provides a preparation system for nickel sulfate solution, which system includes:

[0086] A high-temperature reactor 100, including a hot medium cavity and a cold medium cavity, both the hot medium cavity and the cold medium cavity are provided with inlets and outlets;

[0087] A filter 200, including a filter inlet, a filter outlet and a filter medium;

[0088] A secondary preheating tank 300, including a hot medium cavity and a cold medium cavity, both the hot medium cavity and the cold medium cavity are provided with inlets and outlets;

[0089] A flash evaporation kettle 400, including a flash evaporation kettle inlet and a flash evaporation kettle outlet;

[0090] The outlet of the cold medium cavity of the high-temperature reactor 100 is connected to the inlet of the filter 200, the outlet of the filter 200 is connected to the inlet of the hot medium cavity of the secondary preheating tank 300, the outlet of the hot medium cavity of the secondary preheating tank 300 is connected to the inlet of the flash evaporation kettle, and the outlet of the cold medium cavity of the secondary preheating tank is connected to the inlet of the cold medium cavity of the high-temperature reactor 100.

[0091] In some embodiments, a primary preheating tank 500 is further provided downstream of the flash evaporation kettle 400. The primary preheating tank 500 includes a hot medium cavity and a cold medium cavity, and both the hot medium cavity and the cold medium cavity are provided with inlets and outlets;

[0092] The outlet of the cold medium cavity of the high-temperature reactor 100 is connected to the inlet of the filter 200, the outlet of the filter is connected to the inlet of the hot medium cavity of the secondary preheating tank 300, the outlet of the hot medium cavity of the secondary preheating tank 300 is connected to the inlet of the flash evaporation kettle 100, the outlet of the flash evaporation kettle is connected to the inlet of the hot medium cavity of the primary preheating tank 500, the outlet of the cold medium cavity of the primary preheating tank 500 is connected to the inlet of the cold medium cavity of the secondary preheating tank 300, and the outlet of the cold medium cavity of the secondary preheating tank 300 is connected to the inlet of the cold medium cavity of the high-temperature reactor 100.

[0093] Figure 1 The process flow diagram of preparing nickel sulfate solution according to an optional embodiment of the present invention is shown.

[0094] In the embodiment of the present invention, during the process of the crude nickel sulfate solution from the high-temperature reactor to the filter, the secondary preheating tank, the flash evaporation kettle and the primary preheating tank, the solution can enter the next device automatically under the action of pressure, without a pump, reducing the equipment investment.

[0095] Optionally, the filter 200 is a bag filter, and the filter medium of the filter 200 is an acid-resistant and high-temperature-resistant material.

[0096] Optionally, the number of bag filters is not less than 2, for example, it can be 3, 4, 5, 6, 7, or 8.

[0097] The present invention will be described in detail below with examples. In the following examples, unless otherwise specified, the raw materials used are commercially available products.

[0098] In the following examples, the calculation method of the impurity removal efficiency is: Impurity removal efficiency (%) = 1 - (concentration of metal element in solution f × volume of solution f) / (concentration of metal element in crude nickel sulfate solution × volume of crude nickel sulfate solution).

[0099] Preparation Example 1

[0100] Nickel hydroxide intermediate product and sulfuric acid were mixed and leached at 95 °C, and after the feeding was completed, the reaction was continued for 1 h, and the final pH value was 2.1 to obtain a crude nickel sulfate solution; the concentration of sulfuric acid was 98 wt%; the mass ratio of nickel hydroxide intermediate product to 98 wt% sulfuric acid was 1:0.9.

[0101] The analysis results of the crude nickel sulfate solution are shown in Table 1.

[0102] Table 1

[0103] Component <![CDATA[Ni 2+ > <![CDATA[Fe 3+ > <![CDATA[Al 3+ > <![CDATA[Cr 3+ > <![CDATA[Mn 2+ > <![CDATA[Ca 2+ > <![CDATA[Mg 2+ > <![CDATA[Co 2+ > Concentration (g / L) 111.93 0.1 0.3 0.01 15.51 0.55 3.14 6.5

[0104] Example 1

[0105] (1) Take 2 L of the crude nickel sulfate solution shown in Table 1 and heat it to 160 °C, keep it at a constant temperature for 120 min, and then filter it by the bag filtration method. The temperature during filtration is 160 °C, and the filter medium is polytetrafluoroethylene to obtain solution a and impurity removal slag;

[0106] Under high temperature conditions, Fe 3+ , Al 3+ , Cr 3+ hydrolyze to form Fe2O3, H3OAl3(SO4)2(OH)6, H3OAl3(CrO4)2(OH)6 precipitates. At the same time, the solubility of impurities such as MnSO4, CaSO4, and MgSO4 decreases with the increase of temperature and is lower than the impurity concentration in the crude nickel sulfate solution. Under high temperature conditions, Fe 3+ , Al 3+ , Cr 3+ , Mn 2+ , Ca 2+ , Mg 2 +Impurities such as; the impurity removal residue is a mixture of Fe2O3, H3OAl3(SO4)2(OH)6, H3OAl3(CrO4)2(OH)6, MnSO4, CaSO4, and MgSO4, where the content of manganese sulfate is 82.4 wt%, which can be sold directly, effectively reducing the generation of hazardous waste residues.

[0107] (2) Perform a second heat exchange treatment on solution a and solution e to obtain the heated solution b from solution e and the cooled solution c from solution a. Concentrate solution c to obtain solution d;

[0108] Perform a third heat exchange treatment on solution d and the crude nickel sulfate solution to obtain the heated solution e from the crude nickel sulfate solution and the cooled solution f from solution d;

[0109] Heat-treat solution b; solution f is the final target solution obtained. This example realizes the cascaded utilization of thermal energy.

[0110] The analysis results of solution f are shown in Table 2.

[0111] Table 2

[0112]

[0113] It can be seen from the results in the table that:

[0114] 1) The concentration of Ca in solution f after high-temperature impurity removal is 0.17 g / L, which is lower than the normal-temperature saturation concentration of 0.55 g / L, and there will be no situation of CaSO4 scaling and blocking the pipeline; 2+ 2) The nickel concentration in solution f increases by 7.68%, indicating that 7.68% of the water is evaporated by flash evaporation, and the crystallization investment and crystallization energy consumption are reduced by 7.68%;

[0115] 3) The concentrations of ions such as Fe

[0116] 3) The concentrations of ions such as Fe, Al, Cr, Mn, Ca, and Mg in solution f decrease, meeting the requirements of the pre-extraction solution. At the same time, the concentrations of ions such as Mn, Ca, and Mg decrease, reducing the organic flow rate and alkali consumption in the subsequent P204 (extraction agent: bis(2-ethylhexyl) phosphate) impurity extraction process by 60.78%. 3+ Al 3+ Cr 3+ Mn 2+ Ca 2+ Mg 2+ in solution f decrease, meeting the requirements of the pre-extraction solution. At the same time, the concentrations of ions such as Mn 2+ Ca 2+ Mg 2+ in solution f decrease, reducing the organic flow rate and alkali consumption in the subsequent P204 (extraction agent: bis(2-ethylhexyl) phosphate) impurity extraction process by 60.78%.

[0117] Example 2

[0118] A process similar to that of Example 1 was adopted, except that in step (1), 2 L of a crude nickel sulfate solution having a composition as shown in Table 1 was taken, heated to 210° C. and kept at a constant temperature for 5 min, and then filtered by bag filtration at a temperature of 210° C. and a filter medium of titanium fiber, to obtain a solution a and impurity-removed residue;

[0119] The rest remain unchanged to obtain the target solution f;

[0120] The manganese sulfate content in the impurity-removing slag is 81.3 wt %, which can be sold directly, effectively reducing the generation of hazardous waste slag. The analysis results of solution f are shown in Table 3.

[0121] Table 3

[0122]

[0123]

[0124] From the results in the above table we can see that:

[0125] 1) Ca in solution f after high temperature impurity removal 2+ The concentration is 0.14g / L, which is lower than the saturation concentration of 0.55g / L at normal temperature, and there will be no CaSO4 scaling and clogging of the pipeline;

[0126] 2) The nickel concentration in solution f increased by 9.23%, indicating that the flash evaporation of water was 9.23%, and the crystallization investment and crystallization energy consumption decreased by 9.23%;

[0127] 3) Fe in solution f 3+ 、Al 3+ Cr 3+ , Mn 2+ , Ca 2+ Mg 2+ The plasma concentration is reduced to meet the requirements of the pre-extraction solution, and Mn 2+ , Ca 2+ Mg 2+ The plasma concentration is reduced, reducing the organic flow and alkali consumption in the subsequent P204 extraction process by 68.66%.

[0128] Example 3

[0129] A process similar to that of Example 1 was adopted, except that, in step (1), 2 L of a crude nickel sulfate solution having a composition as shown in Table 1 was heated to 180° C. and kept at a constant temperature for 60 min, and then filtered by bag filtration at a temperature of 180° C. and a filter medium of glass fiber, to obtain a solution a and impurity-removed residue;

[0130] The rest remain unchanged to obtain the target solution f;

[0131] Among them, the manganese sulfate content in the impurity removal residue is 81.7 wt%, which can be directly sold, effectively reducing the generation of hazardous waste residues. The analysis results of solution f are shown in Table 4.

[0132] Table 4

[0133]

[0134] It can be seen from the results in the table that:

[0135] 1) The concentration of Ca in solution f after high-temperature impurity removal is 0.16 g / L, which is lower than the normal-temperature saturation concentration of 0.55 g / L, and there will be no situation of CaSO4 scaling and blocking the pipeline; 2+ The concentration of Ca in solution f after high-temperature impurity removal is 0.16 g / L, which is lower than the normal-temperature saturation concentration of 0.55 g / L, and there will be no situation of CaSO4 scaling and blocking the pipeline;

[0136] 2) The nickel concentration in solution f increases by 8.5%, indicating that 8.5% of the water is evaporated by flash evaporation, and the crystallization investment and crystallization energy consumption are reduced by 8.5%;

[0137] 3) The concentrations of Fe 3+ , Al 3+ , Cr 3+ , Mn 2+ , Ca 2+ , Mg 2+ and other plasma concentrations decrease, meeting the requirements of the pre-extraction solution. At the same time, the concentrations of Mn 2+ , Ca 2+ , Mg 2+ and other plasma concentrations decrease, reducing the organic flow rate and alkali consumption in the subsequent P204 impurity extraction process by 62.45%.

[0138] Comparative Example 1

[0139] The process similar to that in Example 1 was adopted. The difference is that in step (1), the temperature during filtration is 140 °C, and solution a and impurity removal residue are obtained;

[0140] The rest remained unchanged, and the target solution f was obtained;

[0141] Among them, the manganese sulfate content in the impurity removal residue is 57.5 wt%. The analysis results of solution f are shown in Table 5.

[0142] Table 5

[0143]

[0144] It can be seen from the results in the table that:

[0145] (1) The overall impurity removal efficiency is relatively low. Especially, the impurity removal efficiency of Mg is 0, indicating that at 140 °C, the solubility of magnesium sulfate is still relatively high, and the impurity removal effect cannot be achieved;

[0146] (2) When the calcium concentration is 0.51 g / L, there is still a possibility of calcium crystallization under the condition that the production line temperature is relatively low (for example, during shutdown or just after startup after shutdown).

[0147] (3) The nickel concentration in solution f increases by 3.6%, indicating that only 3.6% of the flash evaporation water evaporates, and the crystallization investment and crystallization energy consumption only decrease by 3.6%, with an insignificant effect.

[0148] 4) Mn 2+ , Ca 2+ , Mg 2+ The concentrations of these plasma ions do not decrease significantly, and only 9.40% of the organic flow rate and alkali consumption in the subsequent P204 impurity extraction process can be reduced.

[0149] In addition, as can be seen from the above preparation examples and embodiments, by adopting the implementation mode of the present invention, MHP can be leached in a short process. After the obtained crude nickel sulfate solution is subjected to high-temperature impurity removal according to the present invention, the iron ion content is < 0.003 g / L, the aluminum ion content is < 0.003 g / L, the chromium ion content is < 0.003 g / L, the manganese ion content is < 10.0 g / L, the calcium ion content is < 0.2 g / L, and the magnesium ion content is < 0.2 g / L. Moreover, a high impurity removal efficiency is achieved for the metal impurities therein. The iron and aluminum impurity removal efficiency reaches over 99%, the magnesium impurity removal efficiency reaches over 90%, the calcium impurity removal efficiency reaches over 70%, and the manganese impurity removal efficiency reaches over 40%. The impurity removal effect is remarkable, and the process has good economic efficiency.

[0150] The preferred implementation modes of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing a nickel sulfate solution, characterized in that: The method comprises: subjecting a crude nickel sulfate solution to a heating treatment and a solid-liquid separation treatment in sequence to obtain a solution a and impurity-removed slag; The temperature of the heating treatment is 160-210°C; The temperature of the solid-liquid separation treatment is 160-210°C; The crude nickel sulfate solution contains 0.1 to 2 g / L of Fe 3+ , 0.1~1g / L Al 3+ , 0.01~0.5g / L Cr 3+ , 7.5~16g / L Mn 2+ , 0.2~0.6g / L Ca 2+ , 0.2~5g / L Mg 2+ .

2. The method according to claim 1, characterized in that: The heating treatment time is 5 to 120 minutes; And / or, the manganese sulfate content in the impurity-removing slag is ≥80wt%; And / or, the iron content in the solution a is ≤30 mg / L, and the aluminum content is ≤30 mg / L.

3. The method according to claim 1, characterized in that The solid-liquid separation process is carried out by filtering; the filtering medium used in the filtering is acid corrosion resistant and high temperature resistant material; Optionally, the filter medium is selected from at least one of polytetrafluoroethylene, glass fiber, carbon fiber, metal fiber, and ceramic fiber; Optionally, the metal fiber is selected from at least one of titanium fiber, 904 stainless steel fiber, and Hastelloy fiber.

4. The method according to claim 1, characterized in that: The crude nickel sulfate solution is prepared by the following method: mixing and leaching the nickel hydroxide intermediate with sulfuric acid to obtain the crude nickel sulfate solution; Optionally, the concentration of the sulfuric acid is 12 to 99 wt %; Optionally, the mass ratio of the nickel hydroxide intermediate to the amount of sulfuric acid is 1:(0.7-7.5); Optionally, the mixed leaching conditions include: a temperature of 60 to 110° C. and an endpoint pH value of 1.0 to 4.

0.

5. The method according to claim 1, characterized in that The method further comprises: The solution a and the crude nickel sulfate solution are subjected to a first heat exchange treatment to obtain a heated solution b from the crude nickel sulfate solution and a cooled solution c from the solution a, and the solution c is concentrated to obtain a solution d; The solution b is subjected to the heating treatment.

6. The method according to claim 1, characterized in that The method further comprises: The solution a and the solution e are subjected to a second heat exchange treatment to obtain a heated solution b from the solution e and a cooled solution c from the solution a, and the solution c is concentrated to obtain a solution d; The solution d and the crude nickel sulfate solution are subjected to a third heat exchange treatment to obtain a heated solution e from the crude nickel sulfate solution and a cooled solution f from the solution d; The solution b is subjected to the heating treatment.

7. A system for preparing a nickel sulfate solution, characterized in that: The system includes: A high temperature reaction kettle (100) comprises a hot medium cavity and a cold medium cavity, wherein the hot medium cavity and the cold medium cavity are both provided with an inlet and an outlet; A filter (200) comprising a filter inlet, a filter outlet and a filter medium; The secondary preheating tank (300) comprises a hot medium cavity and a cold medium cavity, wherein the hot medium cavity and the cold medium cavity are both provided with an inlet and an outlet; A flash tank (400) comprising a flash tank inlet and a flash tank outlet; The cold medium cavity outlet of the high temperature reaction kettle (100) is connected to the inlet of the filter (200), the outlet of the filter (200) is connected to the hot medium cavity inlet of the secondary preheating tank (300), the hot medium cavity outlet of the secondary preheating tank (300) is connected to the inlet of the flash kettle (400), and the cold medium cavity outlet of the secondary preheating tank (300) is connected to the cold medium cavity inlet of the high temperature reaction kettle (100).

8. The system according to claim 7, characterized in that A primary preheating tank (500) is further provided downstream of the flash tank (400), wherein the primary preheating tank (500) comprises a hot medium cavity and a cold medium cavity, wherein both the hot medium cavity and the cold medium cavity are provided with an inlet and an outlet; The cold medium cavity outlet of the high temperature reaction kettle (100) is connected to the inlet of the filter, the outlet of the filter (200) is connected to the hot medium cavity inlet of the secondary preheating tank (300), the hot medium cavity outlet of the secondary preheating tank (300) is connected to the inlet of the flash kettle, the outlet of the flash kettle (100) is connected to the hot medium cavity inlet of the primary preheating tank (500), the cold medium cavity outlet of the primary preheating tank (500) is connected to the cold medium cavity inlet of the secondary preheating tank (300), and the cold medium cavity outlet of the secondary preheating tank (300) is connected to the cold medium cavity inlet of the high temperature reaction kettle (100).

9. The system according to claim 7, characterized in that The filter (200) is a bag filter, and the filter medium of the filter (200) is made of acid corrosion-resistant and high temperature-resistant material.

10. The system according to claim 9, characterized in that The number of the bag filters is no less than 2.

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