An improved process for preparing high-purity nickel sulfate from crude nickel sulfate and nickel intermediate products

Abstract

The application discloses a process technical improvement method for preparing high-purity nickel sulfate by taking crude nickel sulfate and nickel intermediate products as main raw materials, and belongs to the technical field of non-ferrous metal compound treatment. After a concentrated sulfuric acid dissolving process in an original process, before chemical purification, a crystallization purification process is added, nickel elements with minimum solubility at the same temperature are precipitated in a large amount by using an existing high-temperature solution. By controlling the temperature, after crystallization and filtration, nickel sulfate heptahydrate crystals with low impurity metal ion content and mother liquor with high impurity metal ion content are obtained. The nickel sulfate heptahydrate crystals are dissolved into a nickel sulfate solution by adding water, the content of impurity metal ions in the solution is reduced by 78% to 96%, and then the solution enters a chemical purification and extraction process to obtain high-purity nickel sulfate. The process technical improvement method can enrich and remove impurity metal ions before the extraction process, greatly reduces auxiliary material and energy consumption, has small nickel loss, high yield, and can obtain high-purity zinc, manganese and nickel compounds from impurities.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal compound processing technology, and in particular relates to an improved process technology for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as the main raw materials. Background Technology

[0002] High-purity nickel sulfate is widely used in industries such as electroplating, automobiles, aerospace, weaponry, metallurgy, and nickel catalysts, and its demand has increased dramatically in recent years. There are two main types of raw materials for producing high-purity nickel sulfate: one is nickel intermediate (MHP) produced by hydrometallurgical processing of laterite deposits (a compound mainly composed of nickel hydroxide, containing 37%-39% nickel, and impurities including 3%-9% manganese, 0.4%-0.8% zinc, 1.5%-4.5% magnesium, and 0.15%-0.25% sodium, etc.); the other is crude nickel sulfate (crude sulfate) produced by metal enterprises after comprehensive gold and silver extraction (containing 13%-14% nickel, and impurities including 4.0%-6.0% zinc, 0.2%-1.8% manganese, 1%-2% magnesium, and 0.05%-0.15% sodium, etc.).

[0003] Currently, the domestic production process for high-purity nickel sulfate is as follows: crude sulfur and MHP are fed in a specific ratio + concentrated sulfuric acid → dissolving solution → chemical purification → solvent extraction → oil removal → evaporation and crystallization → high-purity nickel sulfate solution or high-purity nickel sulfate salt. In this process, after the crude sulfur and MHP are dissolved in concentrated sulfuric acid, acid-soluble impurity elements (such as common elements like manganese, zinc, magnesium, and sodium, hereinafter referred to as impurity metal ions Me) in the raw materials are removed. n+ This will enter the nickel sulfate solution. To obtain high-purity nickel sulfate, chemical purification and extraction separation processes must be performed, and appropriate equipment must be installed to specifically separate and enrich impurity metal ions (Me) from the nickel sulfate solution. n+ .

[0004] The above extraction and impurity removal process, using auxiliary materials such as liquid alkali, hydrochloric acid, and soda ash, as well as energy sources such as water, electricity, and steam, is used to specifically separate and enrich various impurity metal ions (Me). n+ That is, how many impurity metal ions Me enter the solution. n+ The principle is to remove a certain amount of impurity metal ions (Me) through the above process. n+ To meet quality standards, each extraction process requires "over-extraction" in the extraction section, "over-washing" in the washing section, and "over-reverse extraction" in the back-extraction section. The "over" in "over-extraction, over-washing, and over-reverse extraction" means "excessive" or "excessive." Therefore, the amount of auxiliary materials such as liquid alkali, hydrochloric acid, and soda ash added, and the amount of impurity metal ions (Me) are all crucial. n+ The total amount is related to the theoretical reaction amount, and it usually exceeds 1.20-1.50 times, that is, the impurity metal ions Me contained in the nickel sulfate solution. n+The higher the level, the more exponentially the consumption of auxiliary materials increases. The associated equipment investment will also increase exponentially.

[0005] Furthermore, the reaction of crude sulfur and MHP with concentrated sulfuric acid releases a significant amount of heat, raising the solution temperature to 90-95°C. In conventional processes, such high temperatures must be forcibly cooled to below 60°C before proceeding to the next stage to prevent equipment damage. The heat lost during this cooling process is not fully utilized, resulting in substantial energy waste.

[0006] Therefore, there is an urgent need for a new technical solution to address this problem. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide an improved process technology for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials, in order to solve the problem of impurity metal ions Me contained in nickel sulfate solutions in the prior art. n+ Technical problems include high consumption of auxiliary materials and energy, and insufficient utilization of reaction heat in chemical purification, extraction and separation processes.

[0008] The technical solution adopted in this invention is to provide an improved process technology for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials. The process flow includes the following steps:

[0009] a. After crude sulfur and MHP are mixed in the correct ratio, they are reacted with concentrated sulfuric acid to control the total concentration of metal ions in the nickel sulfate solution in the reaction vessel.

[0010] b. Utilize the heat of solution released by the reaction, supplemented by steam heating, to maintain the high temperature of the nickel sulfate solution in the reactor, control the final pH value, so that the slurry is completely dissolved and a crystal film appears on the surface of the solution;

[0011] c. Turn on the cooling water in the jacket of the reactor. After the initial cooling, turn off the cooling water and allow it to cool naturally. Add nickel sulfate crystals as seed crystals according to the solution volume to allow them to nucleate and grow.

[0012] d. After maintaining the temperature for 2 hours and slowly cooling down a second time, solid-liquid separation is performed on the nickel sulfate slurry in the reactor. The produced nickel sulfate heptahydrate solid particles do not need to be dried. After being bagged, they are put into the reactor to dissolve. The nickel sulfate solution then enters the chemical purification → extraction process → oil removal → high-purity nickel sulfate solution → evaporation crystallization → high-purity nickel sulfate solution or high-purity nickel sulfate salt.

[0013] The nickel sulfate mother liquor produced by e is rich in impurity metal ions Me n+ By utilizing the different solubility product rules, appropriate precipitating agents are used to precipitate the impurity metal ions Me in stages. n+The zinc sulfide is separated from the nickel sulfate solution, sodium sulfide is added, and zinc ions precipitate. After plate and frame filtration, zinc sulfide filter cake is produced, and the filtrate enters the next process.

[0014] In the filtrate after zinc removal, manganese sulfide is added to precipitate nickel ions. After plate and frame filtration, nickel sulfide filter cake is produced and put into the dissolution process together with MHP. The filtrate enters the next process.

[0015] Sodium carbonate is added to the filtrate after nickel removal, which precipitates manganese ions. After plate and frame filtration, manganese carbonate filter cake is produced, and the filtrate enters the next process.

[0016] After manganese removal, the filtrate is adjusted to pH 6-9 and then sent to a wastewater treatment plant.

[0017] In step a, the amount of crude sulfur and MHP added is controlled so that the total concentration of metal ions in the nickel sulfate solution in the reactor is 185-195 g / l.

[0018] In step b, the temperature of the nickel sulfate solution in the reactor is maintained at 95-97℃, the final pH value is 2.5±0.5, and a crystalline film appears on the surface of the solution.

[0019] After the initial cooling in step c, the temperature is stabilized at 33±0.5℃ for at least 30 minutes, and the nickel sulfate solution concentration is 40-60 kg / m³. 3 Nickel sulfate grains with a size of 30-40 mesh are added as seed crystals.

[0020] In step d, the secondary cooling rate is 1-2℃ / h. When the temperature of the nickel sulfate slurry in the reactor is in the range of 0-25℃, solid-liquid separation is carried out.

[0021] The nickel sulfide precipitate generated in step f is added together with MHP to the dissolution process to recover valuable nickel metal.

[0022] Through the above design scheme, the present invention can bring the following beneficial effects: based on the impurity metal ions Me in the solution n+ The different solubilities of the components are utilized to achieve evaporation and concentration by taking advantage of the natural exothermic reaction of concentrated sulfuric acid during the dissolution process. Methods such as controlling the final cooling temperature and crystal form (nickel sulfate heptahydrate particle diameter φ > 0.2 mm) are employed to precipitate Ni as nickel sulfate heptahydrate crystals with a purity of over 19%. Impurity metal ions Me in the main raw material are also removed. n+ The zinc, manganese, and nickel-cobalt compounds were concentrated in the mother liquor and then separated into high-purity compounds through chemical purification. After the nickel sulfate heptahydrate crystals dissolved, the impurity metal ions Me... n+ The content is reduced by 78%-96%. The advantages are as follows:

[0023] (1) Low energy consumption. It makes full use of the heat released by the reaction of concentrated sulfuric acid. Only a small amount of steam is needed to complete the temperature control. The heptahydrate nickel sulfate has high purity and can be prepared into a high nickel content solution, which helps to reduce the energy consumption of the evaporation and concentration of nickel sulfate solution.

[0024] (2) Make full use of impurity metal ions such as zinc and manganese Me n+ The inherent solubility characteristics of nickel, when enriched and removed before extraction, make it suitable not only for raw materials with valuable metals as the main component, but also, using the impurity removal method provided by this invention, for removing impurity metal ions such as cobalt and manganese from other raw materials. n+ It has wide applicability;

[0025] (3) Due to the impurity metal ion Me n+ Enrichment and removal before the extraction process reduces the consumption of liquid alkali, hydrochloric acid, sulfuric acid, and hydrogen peroxide, increases the throughput per unit time of the tank, shortens the start-up time, reduces energy consumption, minimizes nickel loss, and achieves a yield of up to 96%.

[0026] (4) This method optimizes and improves the shortcomings of the background technology, does not pollute the environment, reduces carbon emissions, and is friendly to nature. Attached Figure Description

[0027] Figure 1 This is a process flow diagram for producing high-purity nickel sulfate in existing technologies;

[0028] Figure 2 This is a process flow diagram of an improved process technology for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials according to the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0030] This invention adds a crystallization purification step after the concentrated sulfuric acid dissolution process and before chemical purification. Specifically, based on the original process (where crude sulfur and MHP are dissolved in concentrated sulfuric acid at an exothermic temperature exceeding 95°C, then cooled to below 60°C via ventilation for chemical purification), this invention utilizes the existing high-temperature solution to allow nickel, the element with the lowest solubility at the same temperature, to precipitate in large quantities as crystals (due to the dominant content of nickel, sufficient supersaturation is naturally achieved, and impurity metal ions Me...). n+ Due to differences in their solubility, only a small amount precipitates out, while the majority remains in the solution. By controlling the temperature, a slurry mainly composed of nickel sulfate heptahydrate is produced. After filtration, a product containing impurity metal ions Me is obtained. n+ Lower nickel sulfate heptahydrate crystals and impurity metal ions Me n+ The mother liquor has a high concentration of impurity metal ions (Me). This means that during the crystallization process, these impurity metal ions are separated. n+78%-96% of the total (separation amount varies due to impurity metal ions Me) n + (Differences arise due to variations in solubility). The nickel sulfate heptahydrate crystals are then dissolved in water to form a nickel sulfate solution, which subsequently undergoes chemical purification and extraction processes. This process is carried out due to the presence of impurity metal ions (Me). n+ The content is significantly reduced, thereby alleviating the burden of auxiliary materials and energy consumption in each process and reducing costs.

[0031] Control the input of crude sulfur and MHP to keep the total concentration of metal ions in the nickel sulfate solution in the reactor at 185-195 g / l.

[0032] The temperature reached by the heat released from the dissolution of crude sulfur and MHP by concentrated sulfuric acid can also be achieved by passing a small amount of steam to maintain the temperature of the nickel sulfate solution in the reactor at 95-97℃, controlling the final pH value at 2.5±0.5, forming an atmosphere for evaporation and concentration, and causing the solution to form a crystal film.

[0033] Turn on the cooling water in the reactor jacket and quickly cool it to 37±3℃ for the first time, then turn off the cooling water. After the temperature stabilizes at 33±0.5℃ for at least 30 minutes, apply 40-60 kg / m³ of cooling water. 3 Nickel sulfate solution is prepared by adding 30-40 mesh nickel sulfate crystals as seed crystals. The temperature is maintained for 2 hours, then decreased by 1-2°C per hour thereafter. When the temperature of the nickel sulfate slurry in the reactor is within any range of 0-25°C, the bottom valve of the reactor is opened, and the nickel sulfate slurry is placed in a centrifuge for solid-liquid separation. The resulting heptahydrate nickel sulfate solid particles (water content ≤1%) do not require drying; they are bagged and then added to the reactor for dissolution. The resulting nickel sulfate solution undergoes chemical purification → extraction → degreasing → high-purity nickel sulfate solution → evaporation crystallization → high-purity nickel sulfate solution or high-purity nickel sulfate salt. In the extraction process, P204 extractant is used to remove impurities of manganese and zinc from the nickel sulfate solution; P507 extractant is used to initially remove impurities of magnesium; and C272 extractant is used to further remove impurities of magnesium.

[0034] The nickel sulfate mother liquor produced during the centrifugal drying process is rich in impurity metal ions (Me). n+ Elements such as manganese, zinc, magnesium, and sodium are separated from nickel sulfate solution by using appropriate precipitants in stages, taking advantage of their different solubility product rules. Specifically, the pH is adjusted to 3.0±0.5 using lime slurry, and sodium sulfide is used to react with zinc to form zinc sulfide precipitate. After plate and frame filtration, the resulting zinc sulfide filter cake is stored for sale.

[0035] Sulfuric acid is added to the filtrate after zinc removal to adjust the pH to 1-3. Manganese sulfide solution is then added, and the mixture is filtered through a plate and frame filter press to produce a nickel sulfide filter cake. This cake is then fed into the dissolution process along with the MHP (manganese sulfide solution). This effectively recovers valuable nickel.

[0036] Sodium carbonate is added to the filtrate after nickel removal to adjust the pH of the solution to 10.5±0.5. Manganese ions are precipitated as manganese carbonate. After plate and frame filtration, crude manganese carbonate filter cake is produced and stored for sale.

[0037] The pH of the filtrate after manganese removal is adjusted to 6-9 and then sent to the wastewater treatment plant.

[0038] Example 1

[0039] The crude sulfur and MHP produced by a domestic metal materials company after comprehensive gold and silver extraction were used as raw materials.

[0040] 1) Sulfuric acid dissolution

[0041] Add 4.5m to reactor #1 3 Bottom water: 6 tons of crude sulfur and 5 tons of MHP were added to the reactor, followed by the slow addition of 850 liters of concentrated sulfuric acid. The reaction was allowed to proceed for 8 hours, resulting in a relatively complete dissolution of the nickel material. Then, 750 liters of hydrogen peroxide were added to adjust the pH to 2.75, and samples were sent for testing.

[0042]

[0043] 2) Crystallization and purification

[0044] The cooling water in the reactor jacket was turned on, and the first cooling process to 37°C took 1.2 hours. The cooling water was then turned off, and the reactor was allowed to cool naturally for 30 minutes. At 32.7°C, 600 kg of 30-mesh nickel sulfate crystals were added as seed crystals. The temperature was maintained for 2 hours, and then the cooling water in the reactor jacket was turned on again for a second cooling process, which took 7 hours, resulting in a measured temperature of 19.7°C.

[0045] 3) Centrifugal separation

[0046] Open the bottom valve of the reactor and inject the crystal slurry into the No. 1 top-suspended centrifuge through the discharge pipe. Feed at low speed until full, then increase the speed to high and maintain for 2 minutes. Reduce the speed to low and stop the reactor to unload 260 kg of material. A total of 7.03 tons of nickel sulfate heptahydrate crystals were produced, with the following composition:

[0047]

[0048] 4) Crystal dissolution and purification

[0049] Add 14m to reactor #2 3 7.03t of pure water was added to nickel sulfate crystals, which dissolved completely. The solution was then filtered through a two-stage plate and frame filter press. The filtrate was sent to the laboratory to determine the content of each element in the solution.

[0050]

[0051] 5) Extraction and impurity removal

[0052] The second-stage plate and frame filter press filtrate is used as the extraction stock solution. P204 is added for extraction to remove zinc and manganese, with an O / A ratio of 1.2:1. The resulting P204 raffinate is a nickel sulfate solution containing 0.0005 g / L zinc and 0.0008 g / L manganese. This raffinate is then used as the stock solution for extraction with P507 to remove magnesium, with an O / A ratio of 1:1. The resulting P507 raffinate is a nickel sulfate solution containing 0.03 g / L magnesium. This raffinate is then used as the stock solution for extraction with C272 to remove magnesium, with an O / A ratio of 1:1. The resulting raffinate is a nickel sulfate solution.

[0053]

[0054] 6) The high-purity nickel sulfate produced after degreasing, evaporation, crystallization, and packaging has the following content:

[0055]

[0056] 7) Recovery of valuable nickel from centrifuged mother liquor

[0057] Zinc sulfide recovery: Centrifugation yielded 3.61 ml of nickel sulfate mother liquor. 3 Pour the solution into purification reactor #1. Slowly add 0.36 tons of sodium sulfide (concentration 201g / l) solution into the reactor. React for 2 hours, control the final pH value to 3.85, and zinc sulfide precipitate will appear. After two-stage plate and frame filtration, unload the zinc sulfide filter cake into a ton bag, send it for analysis, and store it in the warehouse for sale. Pour the filtrate into purification reactor #2.

[0058]

[0059] Nickel sulfide recovery: Sulfuric acid was added to purification reactor #2 to adjust the pH value to 1.35. 0.63 tons of manganese sulfide were added to the reactor and reacted for 2 hours. The final pH value was controlled at 5.65, and nickel sulfide precipitate appeared. After two-stage plate and frame filtration and washing with tap water, the nickel sulfide filter cake was unloaded into a ton bag, sent for sample analysis, and then stored in the warehouse for later use. The filtrate was poured into purification reactor #3.

[0060]

[0061] Manganese carbonate recovery: Add 0.76 tons of soda ash (concentration 200g / l) to the purification reactor No. 3 and react for 2 hours. Control the final pH value to 9.6. Manganese carbonate precipitate will be produced. After two-stage plate and frame filtration, the sodium carbonate filter cake will be unloaded into a ton bag, sent for sample analysis, and then stored for later use. The filtrate will be sent to the wastewater treatment plant.

[0062]

[0063] The technical and economic indicators are as follows: the direct nickel recovery rate is 97.42%, and the quota for auxiliary materials is 5,500 yuan / tNi.

[0064] Example 2

[0065] The crude sulfur and MHP produced by a domestic metal materials company after comprehensive gold and silver extraction were used as raw materials.

[0066] 1) Sulfuric acid dissolution

[0067] Add 4.2m to reactor #1 3 Bottom water was added, along with 2 tons of crude sulfur and 7 tons of MHP to the reactor. 1190 liters of concentrated sulfuric acid were then slowly added, and the reaction proceeded for 8 hours, allowing the nickel to dissolve relatively completely. 590 liters of hydrogen peroxide were then added to adjust the pH to 2.66, and samples were sent for testing.

[0068]

[0069] 2) Crystallization and purification

[0070] The cooling water in the reactor jacket was turned on, and the first cooling process reached 36.9℃, taking 1.2 hours. The cooling water was then turned off, and the reactor was allowed to cool naturally for 30 minutes. At 32.6℃, 650 kg of 40-mesh nickel sulfate crystals were added as seed crystals. The temperature was maintained for 2 hours, and then the cooling water in the reactor jacket was turned on for a second cooling process, taking 7 hours. The measured temperature at this point was 19.2℃.

[0071] 3) Centrifugal separation

[0072] Open the bottom valve of the reactor and inject the crystal slurry into the No. 1 top-suspended centrifuge through the discharge pipe. Feed at low speed until full, then increase the speed to high and maintain for 2 minutes. Reduce the speed to low and stop the reactor to unload 255 kg of material. A total of 5.87 tons of nickel sulfate heptahydrate crystals were produced, with the following composition:

[0073]

[0074] 4) Crystal dissolution and purification

[0075] Add 12m to reactor #2 3 5.87t of pure water was added to nickel sulfate crystals, which dissolved completely. The solution was then filtered through a two-stage plate and frame filter press. The filtrate was sent to the laboratory to determine the content of each element in the solution.

[0076]

[0077] 5) Extraction and impurity removal

[0078] The second-stage plate and frame filter press filtrate is used as the extraction stock solution. P204 is added for extraction to remove zinc and manganese, with an O / A ratio of 1.2:1. The resulting P204 raffinate is a nickel sulfate solution containing 0.0005 g / L zinc and 0.0008 g / L manganese. This raffinate is then used as the stock solution for extraction with P507 to remove magnesium, with an O / A ratio of 1:1. The resulting P507 raffinate is a nickel sulfate solution containing 0.03 g / L magnesium. This raffinate is then used as the stock solution for extraction with C272 to remove magnesium, with an O / A ratio of 1:1. The resulting raffinate is a nickel sulfate solution.

[0079]

[0080] 6) The high-purity nickel sulfate produced after degreasing, evaporation, crystallization, and packaging has the following content:

[0081]

[0082] 7) Recovery of valuable nickel from centrifuged mother liquor

[0083] Zinc sulfide recovery: Centrifugation yielded 3.02 ml of nickel sulfate mother liquor. 3 Pour the solution into purification reactor #1. Slowly add 0.17 tons of sodium sulfide (concentration 200g / l) solution into the reactor. React for 2 hours, control the final pH value to 3.65, and zinc sulfide precipitate will appear. After two-stage plate and frame filtration, unload the zinc sulfide filter cake into a ton bag, send it for analysis, and store it in the warehouse for sale. Pour the filtrate into purification reactor #2.

[0084]

[0085] Nickel sulfide recovery: Add sulfuric acid to purification reactor #2 to adjust the pH value to 1.30. Add 0.52 tons of manganese sulfide to the reactor and react for 2 hours. Control the final pH value to 5.75. Nickel sulfide precipitate will appear. After two-stage plate and frame filtration and washing with tap water, unload the nickel sulfide filter cake into a ton bag, send it for analysis, and store it in the warehouse for later use. Pour the filtrate into purification reactor #3.

[0086]

[0087] Manganese carbonate recovery: Add 1.06 tons of soda ash (concentration 202g / l) to the purification reactor No. 3 and react for 2 hours. Control the final pH value to 9.75. Manganese carbonate precipitate will be produced. After two-stage plate and frame filtration, the sodium carbonate filter cake will be unloaded into a ton bag, sent for sample analysis, and then stored for later use. The filtrate will be sent to the wastewater treatment plant.

[0088]

[0089] The technical and economic indicators are as follows: the direct nickel recovery rate is 97.68%, and the quota for auxiliary materials is 5,900 yuan / tNi.

[0090] Example 3

[0091] The crude sulfur and MHP produced by a domestic metal materials company after comprehensive gold and silver extraction were used as raw materials.

[0092] 1) Sulfuric acid dissolution

[0093] Add 4.2m to reactor #1 3Bottom water: Add 5 tons of crude sulfur and 5 tons of MHP to the reactor, then slowly add 850 liters of concentrated sulfuric acid. React for 8 hours to allow the nickel material to dissolve relatively completely. Add 650 liters of hydrogen peroxide to adjust the pH to 2.26, and send samples for testing.

[0094]

[0095] 2) Crystallization and purification

[0096] The cooling water in the reactor jacket was turned on, and the first cooling process reached 36.9℃, taking 1.2 hours. The cooling water was then turned off, and the reactor was allowed to cool naturally for 30 minutes. At 32.6℃, 642 kg of 40-mesh nickel sulfate crystals were added as seed crystals. The temperature was maintained for 2 hours, and then the cooling water in the reactor jacket was turned on for a second cooling process, taking 7 hours. The measured temperature at this point was 19.3℃.

[0097] 3) Centrifugal separation

[0098] Open the bottom valve of the reactor and inject the crystal slurry into the No. 1 top-suspended centrifuge through the discharge pipe. Feed at low speed until full, then increase the speed to high and maintain for 2 minutes. Reduce the speed to low and stop the reactor to unload 260 kg of material. A total of 6.41 tons of nickel sulfate heptahydrate crystals were produced, with the following composition:

[0099]

[0100] 4) Crystal dissolution and purification

[0101] Add 12.7m to reactor #2 3 6.41 tons of pure water were added to nickel sulfate crystals, which dissolved completely. The solution was then filtered through a two-stage plate and frame filter press. The filtrate was sent to the laboratory to determine the content of each element in the solution.

[0102]

[0103] 5) Extraction and impurity removal

[0104] The second-stage plate and frame filter press filtrate is used as the extraction stock solution. P204 is added for extraction to remove zinc and manganese, with an O / A ratio of 1.2:1. The resulting P204 raffinate is a nickel sulfate solution containing 0.0005 g / L zinc and 0.0008 g / L manganese. This raffinate is then used as the stock solution for extraction with P507 to remove magnesium, with an O / A ratio of 1:1. The resulting P507 raffinate is a nickel sulfate solution containing 0.03 g / L magnesium. This raffinate is then used as the stock solution for extraction with C272 to remove magnesium, with an O / A ratio of 1:1. The resulting raffinate is a nickel sulfate solution.

[0105]

[0106] 6) The high-purity nickel sulfate produced after degreasing, evaporation, crystallization, and packaging has the following content:

[0107]

[0108] 7) Recovery of valuable nickel from centrifuged mother liquor

[0109] Zinc sulfide recovery: Centrifugation yielded 3.29 ml of nickel sulfate mother liquor. 3 Pour the solution into purification reactor #1. Slowly add 0.31 tons of sodium sulfide (concentration 200g / l) solution into the reactor. React for 2 hours, control the final pH value to 3.60, and zinc sulfide precipitate will appear. After two-stage plate and frame filtration, unload the zinc sulfide filter cake into a ton bag, send it for analysis, and store it in the warehouse for sale. Pour the filtrate into purification reactor #2.

[0110]

[0111] Nickel sulfide recovery: Sulfuric acid was added to purification reactor #2 to adjust the pH value to 1.35. 0.57 tons of manganese sulfide were added to the reactor and reacted for 2 hours. The final pH value was controlled at 5.80, and nickel sulfide precipitate appeared. After two-stage plate and frame filtration and washing with tap water, the nickel sulfide filter cake was unloaded into a ton bag, sent for sample analysis, and then stored in the warehouse for later use. The filtrate was poured into purification reactor #3.

[0112]

[0113] Manganese carbonate recovery: Add soda ash to purification reactor #3 at a dosage of 0.76 tons (concentration 200g / l). React for 2 hours, control the final pH value to 9.69, and manganese carbonate precipitate will be produced. After two-stage plate and frame filtration, the sodium carbonate filter cake will be unloaded into a ton bag, sent for sample analysis, and then stored for later use. The filtrate will be sent to the wastewater treatment plant.

[0114]

[0115] The technical and economic indicators are as follows: the direct nickel recovery rate is 97.86%, and the quota for auxiliary materials is 5,850 yuan / tNi.

[0116] The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. An improved process technology for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials, characterized in that: The process flow includes the following steps: a. After crude sulfur and MHP are mixed in the correct ratio, they are reacted with concentrated sulfuric acid to control the total concentration of metal ions in the nickel sulfate solution in the reaction vessel. b. Utilize the heat of solution released by the reaction, supplemented by steam heating, to maintain the high temperature of the nickel sulfate solution in the reactor, control the final pH value, so that the slurry is completely dissolved and a crystal film appears on the surface of the solution; c. Turn on the cooling water in the jacket of the reactor. After the initial cooling, turn off the cooling water and allow it to cool naturally. Add nickel sulfate crystals as seed crystals according to the solution volume to allow them to nucleate and grow. d. After maintaining the temperature for 2 hours and slowly cooling down a second time, solid-liquid separation is performed on the nickel sulfate slurry in the reactor. The produced nickel sulfate heptahydrate solid particles do not need to be dried. After being bagged, they are put into the reactor to dissolve. The nickel sulfate solution then enters the chemical purification → extraction process → oil removal → high-purity nickel sulfate solution → evaporation crystallization → high-purity nickel sulfate salt. After the secondary cooling in step d, the nickel sulfate slurry in the reactor is placed in a centrifuge for solid-liquid separation. After centrifugation to separate the heptahydrate nickel sulfate solid particles, the remaining solution is the nickel sulfate mother liquor, which is rich in impurity metal ions Me. n+ By utilizing the different solubility product rules, appropriate precipitating agents are used to precipitate the impurity metal ions Me in stages. n+ The zinc sulfide is separated from the nickel sulfate solution, sodium sulfide is added, and zinc ions precipitate. After plate and frame filtration, zinc sulfide filter cake is produced, and the filtrate enters the next process. In the filtrate after zinc removal, manganese sulfide is added to precipitate nickel ions. After plate and frame filtration, nickel sulfide filter cake is produced and put into the dissolution process together with MHP. The filtrate enters the next process. Sodium carbonate is added to the filtrate after nickel removal, which precipitates manganese ions. After plate and frame filtration, manganese carbonate filter cake is produced, and the filtrate enters the next process. After manganese removal, the filtrate is adjusted to pH 6-9 and then sent to a wastewater treatment plant.

2. The improved process technology method for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials according to claim 1, characterized in that: In step a, the amount of crude sulfur and MHP added is controlled so that the total concentration of metal ions in the nickel sulfate solution in the reactor is 185-195 g / l.

3. The improved process technology method for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials according to claim 1, characterized in that: In step b, the temperature of the nickel sulfate solution in the reactor is maintained at 95-97℃, the final pH value is 2.5±0.5, and a crystalline film appears on the surface of the solution.

4. The improved process technology method for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials according to claim 1, characterized in that: After the initial cooling in step c, the temperature is stabilized at 33±0.5℃ for more than 30 minutes. Nickel sulfate crystals with a size of 30-40 mesh are added as seed crystals according to a nickel sulfate solution concentration of 40-60 kg / m³.

5. The improved process technology method for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials according to claim 1, characterized in that: In step d, the secondary cooling rate is 1-2℃ / h. When the temperature of the nickel sulfate slurry in the reactor is in the range of 0-25℃, solid-liquid separation is carried out.

6. The improved process technology method for preparing high-purity nickel sulfate using crude nickel sulfate and nickel intermediates as main raw materials according to claim 1, characterized in that: The nickel sulfide precipitate generated in step f is added together with MHP to the dissolution process to recover valuable nickel metal.

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