Method and system for preparing nickel sulfate products

Abstract

The present disclosure is directed to methods and systems for dissolving elemental nickel in a sulfuric acid solution to produce a nickel sulfate product, and nickel sulfate products suitable for, for example, manufacturing battery materials.

Description

[Technical field]

[0001] This application claims the benefit of European Patent Application No. 21188970.4, filed July 30, 2021, the contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] Nickel sulfate is useful in many applications, for example as an electrode material for nickel metal hydride batteries and lithium ion batteries. These types of batteries are used in hybrid electric vehicles, mobile phones, personal computers, etc. Therefore, there has been an increasing demand for them, especially over the past decade, and this need continues to grow at a high rate.

[0003] One method for producing nickel sulfate is by dissolving elemental nickel in sulfuric acid. This process requires a safe environment because volatile hydrogen gas is evolved during the process, creating a hazardous environment. Furthermore, the process of dissolving elemental nickel in an aqueous solution of acid is often impractically slow for most non-oxidizing acids and even some oxidizing acids under certain conditions.

[0004] For example, US Patent No. 6,554,915 describes a method of dissolving metallic nickel in a non-oxidizing acidic aqueous solution, but in this case, if the nickel used is not in the form of a fine powder, an additional oxidizing agent must be used. However, if the final nickel salt solution contains oxidizing agents such as ozone or hydrogen peroxide, it cannot be used for some applications and additional post-treatment is required to purify the product. Such additional steps increase costs and reduce the efficiency of the process. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 6,554,915 Summary of the Invention [Problem to be solved by the invention]

[0006] Another consideration in producing nickel sulfate is that nickel sulfate used as a raw material in battery manufacturing should have a relatively high pH, ​​e.g., about 4. However, the rate of reaction between elemental nickel and sulfuric acid requires a sufficiently low pH (about 0.5 to about 2) when reacted in the absence of an oxidizing agent.

[0007] Therefore, there is a need for alternative methods and systems for producing nickel sulfate products, such as nickel sulfate products suitable for use as a feedstock in battery manufacturing, in a cost-effective and safe manner. [Means for solving the problem]

[0008] The present disclosure is directed to methods and systems for dissolving elemental nickel in a sulfuric acid solution to produce a nickel sulfate product, such as a nickel sulfate product suitable for battery material manufacturing. In the present disclosure, it has been surprisingly discovered that a two-stage setup using two vessels has the advantage that a pH gradient can be created to produce a nickel sulfate product having a relatively high pH, ​​such as between about 2 and about 4. In the present disclosure, it has also been surprisingly discovered that clean hydrogen gas is produced as an off-gas, which can be further used in the process and system, for example, to generate heat, or can be used in other processes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present disclosure provides a method for preparing a nickel sulfate product. The method can include introducing elemental nickel, sulfuric acid, and water into a primary vessel to form a primary nickel sulfate solution. The primary nickel sulfate solution can be transferred from the primary vessel to a secondary vessel, and additional elemental nickel can be added. The secondary vessel can recover unreacted nickel from the primary vessel and further react the primary nickel sulfate solution with the unreacted nickel to form a secondary nickel sulfate solution.

[0010] The method may include collecting a high purity hydrogen off-gas stream from the primary vessel and / or secondary vessel. The high purity hydrogen off-gas stream may be used to heat water to produce steam to control the temperature of the process in the primary vessel and / or secondary vessel. The process may be free of oxygen, air, and hydrogen peroxide. The method may be carried out at a temperature ranging from about 40° C. to about 200° C. The method may use elemental nickel, which may be in a form selected from pellets, rounds, cathodes, briquettes, powder, and combinations thereof. The method may further include continuously circulating the primary nickel sulfate solution and the secondary nickel sulfate solution in each vessel. The method may be carried out using a dispersion device to minimize foam formation in the primary vessel and / or the secondary vessel. The dispersion device may be selected from a sprinkler, a steamer, a centrifuge, and combinations thereof. The method of the present disclosure may be carried out at pressures above ambient pressure and under an inert atmosphere. The inert atmosphere may be selected from hydrogen, water vapor, nitrogen, argon, and combinations thereof. The method may also be carried out at ambient pressure.

[0011] The primary nickel sulfate solution contains nickel in the range of about 70 g / l to about 200 g / l. 2+ The secondary nickel sulfate solution may have a concentration and a pH in the range of about 0.5 to about 2. The secondary nickel sulfate solution may be filtered to produce a nickel sulfate product, which may be suitable for use without further purification.

[0012] The present disclosure also provides a system for preparing a nickel sulfate product, which may include a primary vessel, a secondary vessel, an off-gas stream line, and a filter.

[0013] The primary vessel may include a settler for mixing elemental nickel, sulfuric acid, and water to form the primary nickel sulfate solution.

[0014] The secondary vessel may include a settler for collecting unreacted nickel particles and the primary nickel sulfate solution and further mixing with additional elemental nickel to form a secondary nickel sulfate solution.

[0015] The primary vessel and / or the secondary vessel may further include one or more circulation devices for circulating the primary and / or secondary nickel sulfate solutions. The circulation devices may be selected from a separator, one or more pumps, and combinations thereof. The primary vessel and / or the secondary vessel may further include a dispersion device for minimizing foam formation therein. The dispersion device may be selected from a sprinkler, a steamer, a centrifuge, and combinations thereof.

[0016] The off-gas flow line may be used to recover high purity hydrogen off-gas from the primary vessel and / or secondary vessel. The off-gas flow line may be connected from the head of the primary vessel and / or the head of the secondary vessel to a burner to heat water to generate steam. Tubes may be included to carry the generated steam to the bottom of the primary vessel and / or the bottom of the secondary vessel and to control the temperature within the primary vessel and / or secondary vessel.

[0017] A filter may be used to filter the secondary nickel sulfate solution to recover the nickel sulfate product. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagrammatic representation showing a comparative example of a one-column configuration for producing a nickel sulfate product. [Diagram 2] FIG. 2 is a diagrammatic representation showing a prophetic example of a two-column configuration for the production of a nickel sulfate product in accordance with one embodiment of the present disclosure.

[0019] As used herein, "a" or "an" entity refers to one or more of that entity; for example, "a container" refers to one or more containers or at least one container, unless otherwise specified. Thus, the terms "a" (or "an"), "one or more," and "at least one" are used interchangeably herein.

[0020] As used herein, the term "about" means approximately, within a region, approximately, or around. When the term "about" is used with a numerical range, it modifies that range by extending the boundaries above and below the stated numerical values. In general, the term "about" is used herein to modify a numerical value above and below the stated numerical value by a variance of 10%. Values ​​modified by the term "about" also include the specific value. For example, "about 5.0" includes 5.0.

[0021] As used herein, the term "ambient pressure" refers to the pressure of the surrounding air and external environment in which the systems and / or methods of the present disclosure are practiced. Ambient pressure is typically atmospheric pressure.

[0022] As used herein, the term "inert atmosphere" refers to a gaseous environment that is non-reactive in the systems and methods of the present disclosure. For example, an inert atmosphere is a substantially oxygen-free environment that is primarily composed of non-reactive gases. Exemplary non-reactive gases include, for example, nitrogen and argon.

[0023] As used herein, the term "vessel" refers to a structure defining a volume suitable for containing one or more process components, including gases, liquids, solids, and mixtures thereof. The vessels of the present disclosure may be constructed of any suitable material, such as, but not limited to, glass, elemental metals, metal alloys, plastics, laminates, ceramics, or any combination thereof. The vessels may be open to the environment or closed to operate under pressure. The vessels described herein are further configured to include one or more inlets and outlets for receiving and / or discharging components of the processes of the present disclosure.

[0024] In this disclosure, nickel leaching to produce nickel sulfate product is carried out in a primary vessel such as a bubble column or trickle bed reactor as depicted in the accompanying drawings (FIGS. 1 and 2). In a bubble column setup, nickel metal is continuously fed into the primary vessel via a handling device, and sulfuric acid and water are dosed into the primary vessel separately or as a solution using a dispersing device to break up any bubbles that may form. In a trickle bed reactor setup, nickel metal is charged into the vessel, and sulfuric acid and water are introduced into the primary vessel and flow through a bed of nickel metal particles, leaching the particles to form a primary nickel sulfate solution. In some embodiments, the nickel metal particles are configured as one large bed in the primary vessel. In some embodiments, the nickel metal particles are configured as multiple beds in respective shells in the primary vessel. In some embodiments, the nickel metal particles are configured as multiple horizontal beds. In some embodiments, the nickel metal particles are configured as multiple parallel packed tubes.

[0025] This process is carried out in the absence of oxygen and under an inert atmosphere at atmospheric pressure and at a temperature of about 50°C to about 120°C.

[0026] An off-gas stream containing primarily hydrogen and water vapor is produced at the top (head) of the primary vessel. The water vapor is condensed in a condenser and returned to the primary vessel, and hydrogen gas can flow through the condenser and may be recovered. The primary nickel sulfate solution produced in the primary vessel is then fed to a secondary vessel for further reaction with unreacted nickel metal recovered from the primary vessel and fresh nickel metal added to the secondary vessel. The secondary vessel may be a bubble column or trickle bed reactor.

[0027] In both the primary and secondary vessels, the nickel sulfate solution is continuously circulated from the bottom to the head of the vessel using one or more pumps. This action helps to maintain dispersion of the nickel particles in the nickel sulfate solution and to prevent settling of the particles.

[0028] The second step of the process produces a secondary nickel sulfate solution having a higher pH and higher nickel concentration than the primary nickel sulfate solution, which is filtered to produce the desired nickel sulfate product of the desired concentration and pH.

[0029] The secondary nickel sulfate solution is passed through a settler which retains the nickel particles in the secondary vessel. Finally, the secondary nickel sulfate solution is cooled, for example, using a heat exchanger (such as an air cooler) to about 50°C, and then passed through a filter, such as a cross-flow filter, to remove any fine particles not separated by the settler. The filtered solution is passed to a storage tank and stored as a nickel sulfate product having the desired nickel concentration and pH specifications. The slurry from the filtration, with the particles concentrated, is discarded. It is also possible to dissolve the particles using about 18 wt% to about 96 wt% sulfuric acid, for example about 18 wt% to about 50 wt% sulfuric acid, and return the resulting solution to the primary vessel. Alternatively, the particles can be recovered from the slurry and returned to the primary vessel as solid particles.

[0030] The process is slightly exothermic, so heat must be introduced into the process. Hydrogen generated as a by-product and from the recovered off-gas stream can be used thermally in a burner to heat a water-filled steam drum used in the process. The steam thus produced can be supplied to the primary and / or secondary vessels as a heat source to control temperature.

[0031] The following description provides various embodiments of different aspects of the disclosed methods and systems for dissolving elemental nickel in a sulfuric acid solution to provide a nickel sulfate product, such as a nickel sulfate product suitable for manufacturing a battery material.

[0032] process The present disclosure provides a method for preparing a nickel sulfate product comprising the steps of: (a) introducing elemental nickel, sulfuric acid, and water into a primary vessel to form a primary nickel sulfate solution; (b) transferring the primary nickel sulfate solution from the primary container to a secondary container and adding additional elemental nickel, the secondary container recovering unreacted nickel and further reacting the primary nickel sulfate solution with the unreacted nickel to form a secondary nickel sulfate solution; (c) recovering the high purity hydrogen off-gas stream from the primary vessel and / or the secondary vessel; and (d) filtering the secondary nickel sulfate solution to recover product nickel sulfate; The present invention provides a method comprising:

[0033] In some embodiments, the method does not include oxygen, in some embodiments, the method does not include air, in some embodiments, the method does not include hydrogen peroxide.

[0034] In some embodiments, the method of the present disclosure produces a high purity hydrogen off-gas. In some embodiments, the high purity hydrogen off-gas is in the range of about 50% to about 100% pure hydrogen. In some embodiments, the hydrogen off-gas is about 50% pure. In some embodiments, the hydrogen off-gas is about 60% pure. In some embodiments, the hydrogen off-gas is about 70% pure. In some embodiments, the hydrogen off-gas is about 80% pure. In some embodiments, the hydrogen off-gas is about 90% pure. In some embodiments, the hydrogen off-gas is about 95% pure. In some embodiments, the hydrogen off-gas is about 100% pure. In some embodiments, the purity of the hydrogen off-gas depends on the inert atmosphere used in the method. In some embodiments, the high purity hydrogen off-gas stream is delivered to a burner and used to heat water to produce steam. In some embodiments, the burner is a porous burner. In some embodiments, the steam is used as a heat source in the method. In some embodiments, the steam produced is returned to the bottom of the primary vessel and fed and used as a heat source to heat the primary nickel sulfate solution. In some embodiments, the generated steam is returned and fed to the bottom of the secondary vessel and used as a heat source to heat the secondary nickel sulfate solution. In some embodiments, the generated steam is returned and fed to the bottom of the primary and secondary vessels and used as a heat source to heat the primary and secondary nickel sulfate solutions.

[0035] In some embodiments, the method is carried out at a temperature ranging from about 40° C. to about 200° C. In some embodiments, the method is carried out at a temperature ranging from about 50° C. to about 180° C. In some embodiments, the method is carried out at a temperature ranging from about 60° C. to about 160° C. In some embodiments, the method is carried out at a temperature ranging from about 70° C. to about 140° C. In some embodiments, the method is carried out at a temperature ranging from about 80° C. to about 120° C. In some embodiments, the method is carried out at a temperature of about 80° C. In some embodiments, the method is carried out at a temperature of about 90° C. In some embodiments, the method is carried out at a temperature of about 100° C. In some embodiments, the method is carried out at a temperature of about 110° C. In some embodiments, the method is carried out at a temperature of about 120° C. In some embodiments, the primary container and secondary container are at the same or different temperatures within the range of about 40° C. to about 200° C.

[0036] In some embodiments, the elemental nickel particles are irregularly shaped and sized. In some embodiments, the elemental nickel particles are uniformly shaped and sized. In some embodiments, the elemental nickel particles are in chunks. In some embodiments, the elemental nickel particles are in the form of turnings. In some embodiments, the elemental nickel particles are in the form of pellets. In some embodiments, the elemental nickel particles are in the form of rounds. In some embodiments, the elemental nickel particles are in the form of cathodes. In some embodiments, the elemental nickel particles are in the form of electrode strips. In some embodiments, the elemental nickel particles are in the form of briquettes. In some embodiments, the elemental nickel particles are in the form of powders. In some embodiments, the elemental nickel particles are in the form of one or more combinations of pellets, rounds, cathodes, briquettes, and powders. In some embodiments, the briquettes are powders and / or pieces combined with a binder to form a briquette. In some embodiments, the nickel particles are introduced in liquid form. In some embodiments, the nickel particles are introduced as a liquid containing the nickel particles. In some embodiments, the nickel particles are introduced as a liquid containing nickel / nickel oxide (Ni / NiO) particles.

[0037] In some embodiments, the elemental nickel powder has an average particle size in the range of about 0.01 mm to about 1 mm. In some embodiments, the elemental nickel powder has an average particle size in the range of about 0.01 mm to about 0.15 mm. In some embodiments, the nickel nuggets have a length, width, and height in the range of about 5 mm to about 10 cm. In some embodiments, the nickel turnings (shavings) have a thickness in the range of about 0.1 mm to about 1 mm, a width in the range of about 1 mm to about 5 mm, and a length in the range of about 1 cm to about 20 cm. In some embodiments, the nickel briquettes have a length in the range of about 2 cm to about 4 cm, and a diameter in the range of about 12 mm to about 14 mm. In some embodiments, the nickel electrode pieces have a thickness in the range of about 0.5 mm to about 7 mm. In some embodiments, the nickel electrode pieces have a thickness in the range of about 1 mm to about 10 mm. In some embodiments, the uncut nickel electrode pieces have a thickness ranging from about 1 mm to about 3 mm and an irregular cross section, a diameter at its widest point not exceeding about 40 mm, and an average diameter ranging from about 10 mm to about 30 mm. In some embodiments, the cut nickel electrodes can have a thickness ranging from about 0.5 mm to about 7 mm. In some embodiments, the nickel electrodes are about 10 cm in size.

[0038] In some embodiments, elemental nickel is continuously fed to a primary vessel. In some embodiments, elemental nickel is continuously fed to a secondary vessel. In some embodiments, elemental nickel is continuously fed to a primary vessel and a secondary vessel.

[0039] In some embodiments, elemental nickel is added to the primary and / or secondary reactor vessels in the form of a powder. For example, crude nickel material can be converted to Ni powder by, for example, thermal spraying (i.e., gas atomization), water atomization (high pressure), carbonyl refinement, hydrometallurgy (i.e., hydrogen reduction). (P. Samal, J. Newkirk, ASM Handbook, Volume 7, Powder Metallurgy, 2015). Thus, in some embodiments, powder nickel material can be provided to the primary and / or secondary vessels by direct spraying.

[0040] In some embodiments, the sulfuric acid used to practice the present method is sulfuric acid containing water, which may be protonated or unprotonated. In some embodiments, the water content of the sulfuric acid can range from about 5% to about 95% by weight based on H2SO4. In some embodiments, the water content of the sulfuric acid can range from about 15% to about 30% by weight based on H2SO4. In some embodiments, the concentration of sulfuric acid selected depends on the concentration of the nickel sulfate product of interest.

[0041] In some embodiments, nickel is placed in a primary vessel and water and sulfuric acid are added to form an acidic primary nickel sulfate solution. In some embodiments, the formed acidic primary nickel sulfate solution is continuously removed and fresh nickel, water and / or sulfuric acid is added. In some embodiments, the sulfuric acid is premixed with water and then added as dilute sulfuric acid. In some embodiments, it is possible to recycle the sulfuric acid from the primary vessel. In some embodiments, the recycled sulfuric acid includes nickel ions from the nickel particles.

[0042] In some embodiments, the method is carried out continuously, with the nickel sulfate solution and / or product being removed and replenished with elemental nickel, water and sulfuric acid as needed, hi some embodiments, the method of the present disclosure is carried out batchwise.

[0043] In some embodiments, the primary vessel comprises one or more circulation devices for circulating the primary nickel sulfate solution. In some embodiments, the secondary vessel comprises one or more circulation devices for circulating the secondary nickel sulfate solution. In some embodiments, the primary and secondary vessels comprise one or more circulation devices for circulating the primary and secondary nickel sulfate solutions.

[0044] In some embodiments, the circulation device comprises a separator and / or one or more pumps. In some embodiments, the separator is a loop separator. In some embodiments, the separator is a cyclone separator. In some embodiments, the circulation device is a pump. In some embodiments, the circulation device is two or more pumps. In some embodiments, the circulation device is a combination of a cyclone separator and one or more pumps. In some embodiments, the circulation device is a combination of a loop separator and one or more pumps. Those skilled in the art will recognize or be able to use, with no more than routine experimentation, many equivalents to the circulation devices described herein. Such equivalents are intended to be encompassed herein.

[0045] In some embodiments, foam formation in the primary vessel is minimized using a dispersion device. In some embodiments, foam formation in the secondary vessel is minimized using a dispersion device. In some embodiments, the dispersion device is a sprinkler. In some embodiments, water and sulfuric acid are introduced into the primary vessel using a sprinkler. In some embodiments, the primary nickel sulfate solution is introduced into the secondary vessel using a sprinkler. In some embodiments, the dispersion device is a steamer. In some embodiments, the dispersion device is a centrifuge. In some embodiments, the dispersion device is selected from one or more of a sprinkler, a steamer, and a centrifuge. Those skilled in the art will recognize or be able to use, with no more than routine experimentation, many equivalents to the dispersion devices described herein. Such equivalents are intended to be encompassed herein.

[0046] In some embodiments, the method is carried out at ambient pressure. In some embodiments, the method is carried out at a pressure greater than ambient pressure. In some embodiments, the method is carried out under an inert atmosphere. In some embodiments, the inert atmosphere is hydrogen. In some embodiments, the inert atmosphere is water vapor. In some embodiments, the inert atmosphere is nitrogen. In some embodiments, the inert atmosphere is argon. In some embodiments, the inert atmosphere is a combination of two or more gases selected from hydrogen, water vapor, nitrogen, and argon.

[0047] In some embodiments, the primary nickel sulfate solution has a Ni content in the range of about 70 g / l to about 200 g / l. 2+ In some embodiments, the primary nickel sulfate solution has a Ni concentration in the range of about 90 g / l to about 150 g / l. 2+ In some embodiments, the primary nickel sulfate solution has a Ni concentration in the range of about 100 g / l to about 140 g / l. 2+ In some embodiments, the primary nickel sulfate solution has a concentration of about 110 g / l Ni 2+ In some embodiments, the primary nickel sulfate solution has a concentration of about 118 g / l Ni 2+ In some embodiments, the primary nickel sulfate solution has a concentration of about 120 g / l Ni 2+ In some embodiments, the primary nickel sulfate solution has a concentration of about 130 g / l Ni 2+ In some embodiments, the primary nickel sulfate solution has a concentration of about 140 g / l Ni 2+ In some embodiments, the primary nickel sulfate solution has a concentration of about 120 g / l Ni 2+ It has a concentration.

[0048] In some embodiments, the primary nickel sulfate solution in the primary container has a pH in the range of about 0 to about 2. In some embodiments, the primary nickel sulfate has a pH less than about 0. In some embodiments, the primary nickel sulfate solution has a pH in the range of about 0 to about 1.5. In some embodiments, the primary nickel sulfate solution has a pH of about 1.2. In some embodiments, the primary nickel sulfate solution has a pH of about 1.4. In some embodiments, the primary nickel sulfate solution has a pH of about 1.6. In some embodiments, the primary nickel sulfate solution has a pH of about 1.8. In some embodiments, the pH depends on the concentration of the administered sulfuric acid. In some embodiments, the pH is measured using a glass electrode. In some embodiments, the pH is measured using a combination electrode.

[0049] In some embodiments, the secondary nickel sulfate solution has a Ni content in the range of about 70 g / l to about 200 g / l. 2+ In some embodiments, the secondary nickel sulfate solution has a Ni concentration in the range of about 90 g / l to about 150 g / l. 2+ In some embodiments, the secondary nickel sulfate solution has a Ni concentration in the range of about 100 g / l to about 140 g / l. 2+ In some embodiments, the secondary nickel sulfate solution has a concentration of about 110 g / l Ni 2+ In some embodiments, the secondary nickel sulfate solution has a concentration of about 118 g / l Ni 2+ In some embodiments, the secondary nickel sulfate solution has a concentration of about 120 g / l Ni 2+ In some embodiments, the secondary nickel sulfate solution has a concentration of about 130 g / l Ni 2+ In some embodiments, the secondary nickel sulfate solution has a concentration of about 140 g / l Ni 2+ In some embodiments, the secondary nickel sulfate solution has a concentration of about 150 g / l Ni 2+ In some embodiments, the secondary nickel sulfate solution has a Ni 2+ The concentration is the Ni of the primary nickel sulfate solution. 2+higher than the concentration.

[0050] In some embodiments, the nickel sulfate product has a Ni content in the range of about 70 g / l to about 200 g / l. 2+ In some embodiments, the nickel sulfate product has a Ni concentration in the range of between about 90 g / l and about 150 g / l. 2+ In some embodiments, the nickel sulfate product has a Ni concentration in the range of about 100 g / l to about 140 g / l. 2+ In some embodiments, the nickel sulfate product has a concentration of about 110 g / l Ni 2+ In some embodiments, the nickel sulfate product has a concentration of about 118 g / l Ni 2+ In some embodiments, the nickel sulfate product has a concentration of about 120 g / l Ni 2+ In some embodiments, the nickel sulfate product has a concentration of about 130 g / l Ni 2+ In some embodiments, the nickel sulfate product has a concentration of about 140 g / l Ni 2+ In some embodiments, the nickel sulfate product has a concentration of about 150 g / l Ni 2+ It has a concentration.

[0051] In some embodiments, the nickel sulfate product has a pH in the range of about 2 to about 4. In some embodiments, the nickel sulfate product has a pH in the range of about 2.2 to about 3.8. In some embodiments, the nickel sulfate product has a pH in the range of about 2.4 to about 3.6. In some embodiments, the nickel sulfate product has a pH in the range of about 2.5 to about 3.5. In some embodiments, the nickel sulfate product has a pH of about 2.5. In some embodiments, the nickel sulfate product has a pH of about 2.6. In some embodiments, the nickel sulfate product has a pH of about 2.7. In some embodiments, the nickel sulfate product has a pH of about 2.8. In some embodiments, the nickel sulfate product has a pH of about 2.9. In some embodiments, the nickel sulfate product has a pH of about 3.0.

[0052] In some embodiments, the nickel sulfate product of the present disclosure is suitable for use without further purification. For example, the process includes: (a) introducing elemental nickel, sulfuric acid, and water into a primary vessel to form a primary nickel sulfate solution; (b) transferring the primary nickel sulfate solution from the primary vessel to a secondary vessel and further adding additional elemental nickel, where the secondary vessel recovers unreacted nickel and the primary nickel sulfate solution further reacts with any unreacted nickel to form a secondary nickel sulfate solution; (d) recovering a high purity hydrogen off-gas stream from the primary vessel and / or the secondary vessel; and (d) filtering the secondary nickel sulfate solution to recover a nickel sulfate product. In some embodiments, the nickel sulfate product is filtered over activated carbon to remove organic compounds. In some embodiments, the organic compounds are binders from the nickel briquettes. After filtering the secondary nickel sulfate solution to recover the nickel sulfate product, no further purification is required. The purification or degree of purification of the nickel sulfate product depends on several factors. For example, the purity of the starting materials, i.e., elemental nickel, sulfuric acid, and water, and the continuity of one or more of these materials flowing into the process. The purity of the nickel sulfate product ranges from about 50% to about 100%. In some embodiments, the purity of the nickel sulfate product ranges from about 95% to about 100%. In some embodiments, the purity of the nickel sulfate product ranges from about 98% to about 100%.

[0053] system The present disclosure also provides a system for preparing a nickel sulfate product, the system comprising: (i) a primary vessel with a settler for mixing elemental nickel, sulfuric acid, and water to form a primary nickel sulfate solution; (ii) a secondary vessel with a settler for recovering unreacted nickel particles and the primary nickel sulfate solution and further mixing with additional elemental nickel to form a secondary nickel sulfate solution; (iii) an off-gas stream line for recovering high purity hydrogen off-gas from the primary vessel and / or the secondary vessel; and (iv) a filter for filtering the secondary nickel sulfate solution to recover a nickel sulfate product.

[0054] In some embodiments, the system includes (i) a primary vessel with a settler for mixing elemental nickel, sulfuric acid, and water to form a primary nickel sulfate solution; and (ii) a secondary vessel with a settler for recovering unreacted nickel particles and the primary nickel sulfate solution for further mixing with additional elemental nickel to form a secondary nickel sulfate solution. In some embodiments, the vessel is made of epoxy resin and is unfilled or filled with fiberglass. In some embodiments, the vessel is a laminated epoxy-fiberglass material. In some embodiments, the vessel is a plastic such as polypropylene, PVC, or PVDF. In some embodiments, the vessel includes a plastic tube introduced into a steel outer. In some embodiments, the vessel is made of lead or a lead alloy. In some embodiments, the vessel is a metal vessel such as steel. In some embodiments, the steel vessel is lined with the above materials.

[0055] In some embodiments, the system includes (iii) an off-gas stream line for collecting high purity hydrogen off-gas from the primary vessel and / or the secondary vessel. In some embodiments, the off-gas stream line further connects from the head of the primary vessel to a burner to heat water for steam generation. In some embodiments, the off-gas stream line further connects from the head of the secondary vessel to a burner to heat water for steam generation. In some embodiments, the off-gas stream line further connects from the heads of the primary and secondary vessels to a burner to heat water for steam generation. In some embodiments, the burner is a porous burner.

[0056] In some embodiments, the system further comprises: (iv) a filter for filtering the secondary nickel sulfate solution to recover the nickel sulfate product, hi some embodiments, the filter is a membrane filter.

[0057] In some embodiments, the system further comprises a pipe to deliver the generated steam to the bottom of the primary vessel and control its temperature. In some embodiments, the system further comprises a pipe to deliver the generated steam to the bottom of the secondary vessel and control its temperature. In some embodiments, the system further comprises a pipe to deliver the generated steam to the bottom of the primary vessel and the secondary vessel to control the temperature therein.

[0058] A claim or description including "or" or "and / or" between at least two members of a group is deemed to be satisfied if one, more than one, or all of the members of the group are present in, employed in, or otherwise relevant to a given product, process, or system, unless indicated to the contrary or otherwise clear from the context. The present disclosure includes embodiments in which only one member in the nature of a group is present in, employed in, or otherwise relevant to a given product, process, or system. The present disclosure includes embodiments in which more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product, process, or system.

[0059] Furthermore, the disclosure encompasses all variations, combinations, and permutations in which at least one limitation, element, clause, and descriptive term from at least one of the claims described is introduced into another claim. For example, a claim that is dependent on another claim can be amended to include at least one limitation found in the other claim that is dependent on the same base claim. When elements are presented as a list, such as in Markush group format, each subgroup of elements is also disclosed, and any element can be removed from the group. In general, when the disclosure or aspects of the disclosure are referred to as consisting of certain elements and / or features, it is to be understood that an embodiment of the disclosure or aspects of the disclosure consists of or consists essentially of such elements and / or features. For the sake of brevity, those embodiments have not been specifically described in haec verba herein. When ranges are given, the endpoints are included. Moreover, unless otherwise indicated or apparent from the context and the understanding of one of ordinary skill in the art, values ​​expressed as ranges can assume, in different embodiments of this disclosure, any specific value or subrange within the stated range, unless the context clearly dictates otherwise.

[0060] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein, which equivalents are intended to be encompassed by the claims.

[0061] Before describing example embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following examples, and that other embodiments are possible and that the present disclosure may be practiced or carried out in various ways. EXAMPLES

[0062] The following examples are intended to be illustrative and in no way limiting of the scope of the disclosure.

[0063] Experimental step-up of the one-column process: As shown in Figure 1, the bubble column vessel (1) is equipped with a gas inlet tube (2) for supplying nitrogen gas from a nitrogen gas supply and a handling device (3) for supplying nickel metal particles. The nitrogen gas is used to create an inert atmosphere in the vessel (1) and to mix the reaction mixture therein using nitrogen gas bubbles. The vessel (1) contains two inlet tubes (4 and 5) at the top of the vessel (1) for introducing sulfuric acid and water, respectively. The sulfuric acid and water are introduced into the vessel (1) through a dispersion device (6) to minimize the formation of bubbles.

[0064] The liquid containing the Ni / NiO particles is continuously pumped by pump (11) from the bottom to the top of the vessel (1), through outlet (7) at the bottom of the vessel (1), through separator (8) and heat exchanger (9), and back to the vessel (1) through inlet (10). As the liquid is returned to the top of the vessel (1), it may be introduced through a dispersion device (6). A sampling point (not shown) is provided between the vessel outlet (7) and the separator (8) to allow sampling of the reaction mixture during production. Off-gas containing hydrogen and water vapor is produced in the process and passes through a condenser (12) above the vessel (1). The water vapor condenses and is returned to the vessel (1) during use, while hydrogen gas (13) passes through the condenser (12) and can be recovered for further use. The pH of the reaction mixture, the amount of sulfuric acid and water input, and the nickel mass and concentration of the recovered nickel sulfate product can be continuously monitored during the process. The nickel sulfate product is transferred from vessel (1) via outlet (14) and through filter (15) to separate the nickel sulfate product (17) from the solid waste (16).

[0065] Steps for one column setup: 6 kg of elemental nickel in the form of briquettes was charged into the vessel, and 3.2 L of 18 wt% aqueous sulfuric acid solution was added to the vessel. Nitrogen gas was bubbled through the reaction mixture at 20 nL / h. In this way, the nickel sulfate solution was continuously circulated. The nickel sulfate solution was heated to 80°C (internal temperature), and the amount of nickel used was replenished by continuous addition of nickel briquettes. As soon as the nickel sulfate solution reached the target nickel concentration of 126 g / L, 18 wt% aqueous sulfuric acid solution was added at a rate of 500 nL / h over 5.3 hours. After equilibration, a pH of 1.4 was achieved, and 3419 g of 126 g / L nickel sulfate solution was obtained. The reaction rate of nickel dissolution was determined to be 60 g / h. Nickel briquettes were not continuously fed into the vessel within the 5.3 hour run time.

[0066] Predictive experimental step-up for a two-column process: As shown in Figure 2, the primary vessel (20) bubble column is equipped with a gas inlet tube (21) for supplying nitrogen gas to the bottom of the primary vessel (20). Similarly, the secondary vessel (22) bubble column is equipped with a gas inlet tube (23) for supplying nitrogen gas to the bottom. The nitrogen gas supply is used to create an inert atmosphere within the vessel and to mix the nickel sulfate solution using nitrogen gas bubbles.

[0067] The primary vessel (20) contains two inlet pipes (24 and 25) at the top for introducing sulfuric acid and water, respectively, above the liquid level in the primary vessel (20), and a handling device (27) for feeding nickel metal particles. The sulfuric acid and water are introduced into the primary vessel (20) via the inlet pipes 24 and 25. They can also be introduced via a dispersion device (26) to minimize foaming. The primary vessel (20) is equipped with a primary overflow drain (28) to maintain a constant liquid level therein. The overflow is collected in the secondary vessel (22).

[0068] The top of the primary vessel (20) is provided with an inlet (29) for introducing liquid containing Ni / NiO particles into the primary vessel (20). The liquid is continuously pumped by pump (33) from the bottom of the primary vessel (20) through outlet (30), separator (31), heat exchanger (32) and to the top of the primary vessel (20). A sampling point (not shown) is provided between the primary vessel (20) and separator (31) to allow sampling of the primary nickel sulfate solution during the process.

[0069] The primary vessel (20) is connected by its primary overflow drain (28) to the secondary vessel (22) which has an outlet (34) for removing the secondary nickel sulfate solution produced therein. This secondary nickel sulfate solution in the secondary vessel (22) is continuously circulated through a pump (35) from the bottom of the secondary vessel (22) via a separator (37) and a heat exchanger (38) to the top of the secondary vessel (22) via an outlet (36). At the bottom of the secondary vessel (22), between the outlet (36) and the separator (37), a sampling point (not shown) is provided for sampling the secondary nickel sulfate solution being produced. The secondary nickel sulfate solution is transferred from an inlet (39) to the secondary vessel (22) via a secondary dispersion device (40) to minimize the formation of bubbles. Additional nickel metal can be introduced into the secondary vessel (22) from a handling device (27).

[0070] Off-gas containing hydrogen and water vapor generated during the process passes from the secondary vessel (22) through a condenser (41). The condensed water vapor is returned to the secondary vessel (22) and hydrogen gas (42) is released and can be recovered for further use. For example, the hydrogen gas (42) can be conveyed to a burner and used to heat water to produce water vapor. The steam produced can be fed to the bottom of the primary and secondary vessels as a heat source to control the temperature in the primary and secondary vessels during use.

[0071] Finally, the outlet (34) of the secondary vessel (22) is connected to a filter (43) that is used to separate the solid components (44) from the nickel sulfate final product (45).

[0072] Predictive Procedure for 2 Row Setup: Elemental nickel particles are fed into the primary vessel, and sulfuric acid and water are added to the primary vessel. Nitrogen gas is bubbled through the primary nickel sulfate solution produced in the primary vessel, and the primary nickel sulfate solution is continuously circulated while being heated to about 40°C to about 200°C (internal temperature). Spent elemental nickel in the primary vessel is replenished by the continuous addition of nickel particles. The nickel concentration of the primary nickel solution is determined by measurement of a sample taken between the primary vessel and the separator, and sulfuric acid is added at the required rate for a predetermined period of time, if necessary. After equilibration, and when the primary nickel sulfate solution reaches a desired pH of between about 0.5 and about 2.0 and a desired concentration of between about 90 g / l and about 200 g / l, the primary nickel sulfate solution is passed through the overflow drain of the primary vessel to the secondary vessel, forming a secondary nickel sulfate solution. Nitrogen gas is bubbled through the secondary nickel sulfate solution in the secondary vessel, and the secondary nickel sulfate solution is continuously circulated in this manner. The secondary nickel sulfate solution is also heated to a desired temperature (internal temperature) between about 40° C. and about 200° C. The amount of spent nickel metal in the secondary vessel is replenished by the continuous addition of nickel metal. During the process, the secondary nickel sulfate solution is constantly measured to determine pH, reaction rate, and concentration.

[0073] During this process, off-gas containing water vapor and hydrogen is generated. The water vapor condenses in a condenser at the top of the vessel and the condensate is returned to the vessel. The hydrogen off-gas is conveyed to a burner where it can be used to heat water to generate steam. The steam produced is then returned to the vessel and fed to the bottom of the primary and secondary vessels where it can be used as a heat source to control the temperature in the primary and secondary vessels during use. The primary and secondary vessels can also be heated using a heat exchanger.

[0074] Once the secondary nickel sulfate solution has reached equilibration, a desired pH between about 2.0 and about 4.0, and a desired concentration, the secondary nickel sulfate solution is transferred to a separation system to separate the solid components and obtain a ready-to-use final nickel sulfate product without the need for additional work-up or purification steps.

[0075] Embodiment "Embodiment 1" 1. A method for preparing a nickel sulfate product comprising the steps of: introducing elemental nickel, sulfuric acid and water into a primary vessel to form a primary nickel sulfate solution; transferring the primary nickel sulfate solution from the primary container to a secondary container and adding additional elemental nickel, the secondary container recovering unreacted nickel and further reacting the primary nickel sulfate solution with the unreacted nickel to form a secondary nickel sulfate solution; recovering a high purity hydrogen off-gas stream from the primary vessel and / or the secondary vessel; and filtering the secondary nickel sulfate solution to recover a nickel sulfate product; The method according to claim 1, further comprising:

[0076] "Embodiment 2" 2. The method of embodiment 1, wherein no oxygen is used.

[0077] "Embodiment 3" 3. The method of embodiment 1 or 2, wherein no air is used.

[0078] "Embodiment 4" 4. The method of any one of embodiments 1 to 3, wherein no hydrogen peroxide is used.

[0079] "Embodiment 5" The method of any one of embodiments 1-4, wherein the high purity hydrogen off-gas stream heats water to produce steam.

[0080] "Embodiment 6" 6. The method of embodiment 5, wherein steam is used to control the process temperature in the primary vessel.

[0081] "Embodiment 7" 7. The method of embodiment 5 or 6, wherein steam is used to control the temperature of the process in the secondary vessel.

[0082] "Embodiment 8" 8. The method of any one of the preceding embodiments, wherein the process is carried out at a temperature ranging from about 40° C. to about 200° C.

[0083] "Embodiment 9" 9. The method of any one of the preceding embodiments, wherein the process is carried out at a temperature ranging from about 60° C. to about 150° C.

[0084] "Embodiment 10" 10. The method of any one of the preceding embodiments, wherein the process is carried out at a temperature ranging from about 80° C. to about 100° C.

[0085] 『Embodiment 11』 11. The method of any one of the preceding embodiments, wherein the process is carried out at a temperature of about 80° C.

[0086] 『Embodiment 12』 12. The method of any one of the preceding claims, wherein the elemental nickel particles have irregular shapes and sizes.

[0087] 『Embodiment 13』 13. The method of any one of the preceding embodiments, wherein the elemental nickel is in a form selected from pellets, rounds, cathodes, briquettes, powder, and combinations thereof.

[0088] 『Embodiment 14』 14. The method of any one of embodiments 1-13, wherein elemental nickel is continuously fed to the primary vessel.

[0089] 『Embodiment 15』 15. The method of any one of the preceding embodiments, wherein elemental nickel is continuously fed to the secondary vessel.

[0090] 『Embodiment 16』 16. The method of any one of the preceding embodiments, wherein the primary vessel comprises one or more circulation devices for circulating the primary nickel sulfate solution.

[0091] 『Embodiment 17』 17. The method of any one of the preceding embodiments, wherein the secondary vessel comprises one or more circulation devices for circulating the secondary nickel sulfate solution.

[0092] 『Embodiment 18』 The process according to embodiment 16 or 17, wherein the circulation device is selected from a particle separator, one or more pumps, and combinations thereof.

[0093] 『Embodiment 19』 19. The method of any one of the preceding embodiments, wherein the primary container is equipped with a dispersion device to minimize foam formation.

[0094] 『Embodiment 20』 19. The method of any one of the preceding embodiments, wherein the secondary container is equipped with a dispersion device to minimize foam formation.

[0095] 『Embodiment 21』 21. The method of embodiment 19 or 20, wherein the dispersion device is selected from a sprinkler, a steamer, a centrifuge, and combinations thereof.

[0096] 『Embodiment 22』 22. The method according to any one of the preceding embodiments, wherein the process is carried out at ambient pressure.

[0097] 『Embodiment 23』 22. The method of any one of the preceding embodiments, wherein the step is carried out at a pressure above ambient pressure.

[0098] 『Embodiment 24』 24. The process of any one of the preceding embodiments, wherein the process is carried out under an inert atmosphere.

[0099] 『Embodiment 25』 25. The method of embodiment 24, wherein the inert atmosphere is selected from hydrogen, water vapor, nitrogen, argon, and combinations thereof.

[0100] 『Embodiment 26』 The primary nickel sulfate solution has a Ni concentration in the range of about 70 g / l to about 200 g / l. 2+ 26. The method of any one of the preceding embodiments, having a concentration.

[0101] 『Embodiment 27』 27. The method of any one of the preceding claims, wherein the primary nickel sulfate solution has a concentration in the range of about 90 g / l to about 150 g / l.

[0102] 『Embodiment 28』 The primary nickel sulfate solution has a Ni content in the range of about 110 g / l to about 140 g / l. 2+ 28. The method of any one of the preceding embodiments, having a concentration.

[0103] 『Embodiment 29』 The primary nickel sulfate solution contains approximately 120 g / l of Ni 2+ 29. The method of any one of the preceding embodiments, having a concentration.

[0104] 『Embodiment 30』 30. The method of any one of the preceding embodiments, wherein the primary nickel sulfate solution in the primary container has a pH in the range of about 0 to about 2.

[0105] 『Embodiment 31』 31. The method of any one of the preceding claims, wherein the primary nickel sulfate solution in the primary container has a pH in the range of about 1.0 to about 2.

[0106] 『Embodiment 32』 32. The method of any one of the preceding claims, wherein the primary nickel sulfate solution in the primary container has a pH of about 1.4.

[0107] 『Embodiment 33』 30. The method of any one of the preceding embodiments, wherein the primary nickel sulfate solution in the primary container has a pH of less than about 0.

[0108] 『Embodiment 34』 34. The method of any one of the preceding embodiments, wherein the pH of the primary nickel sulfate solution in the primary container is controlled by the concentration of sulfuric acid added to the primary nickel sulfate solution.

[0109] 『Embodiment 35』 35. The method of any one of the preceding embodiments, wherein the nickel sulfate product has a pH in the range of about 2 to about 4.

[0110] 『Embodiment 36』 36. The method of any one of the preceding embodiments, wherein the nickel sulfate product has a pH in the range of about 2.2 to about 3.8.

[0111] 『Embodiment 37』 37. The method of any one of the preceding embodiments, wherein the nickel sulfate product has a pH in the range of about 2.4 to about 3.6.

[0112] 『Embodiment 38』 38. The method of any one of the preceding embodiments, wherein the nickel sulfate product has a pH in the range of about 2.5 to about 3.5.

[0113] 『Embodiment 39』 39. The method of any one of the preceding embodiments, wherein the nickel sulfate product has a pH of about 3.0.

[0114] 『Embodiment 40』 40. The method of any one of the preceding embodiments, wherein the pH of the nickel sulfate product can be further adjusted by adding one or more metal hydroxides.

[0115] 『Embodiment 41』 41. The method of embodiment 40, wherein the metal hydroxide is selected from NaOH, KOH, Ni(OH)2, and combinations thereof.

[0116] 『Embodiment 42』 42. The method of any one of the preceding embodiments, wherein the nickel sulfate product is suitable for use without further purification.

[0117] 『Embodiment 43』 43. The method of any one of the preceding embodiments, wherein the nickel sulfate product is filtered over activated carbon.

[0118] 『Embodiment 44』 1. A system for preparing a nickel sulfate product, comprising: a primary vessel equipped with a settler for mixing elemental nickel, sulfuric acid, and water to form a primary nickel sulfate solution; a secondary vessel equipped with a settler for collecting unreacted nickel particles and the primary nickel sulfate solution and mixing it with additional elemental nickel to form a secondary nickel sulfate solution; an off-gas flow path for recovering high purity hydrogen off-gas from the primary vessel and / or the secondary vessel; and a filter for filtering the secondary nickel sulfate solution to produce a nickel sulfate product; A system including:

[0119] 『Embodiment 45』 45. The system of embodiment 44, wherein an off-gas line further connects from the head of the primary vessel to a porous burner for heating water to generate steam.

[0120] 『Embodiment 46』 45. The system of embodiment 44, wherein the off-gas line further connects from the head of the secondary vessel to a porous burner for heating water to generate steam.

[0121] 『Embodiment 47』 46. ​​The system of embodiment 45, further comprising a pipe for conveying generated steam to a bottom of the primary vessel to control the temperature therein.

[0122] 『Embodiment 48』 47. The system of embodiment 46, further comprising a pipe for conveying generated steam to a bottom of the secondary vessel to control the temperature therein.

[0123] 『Embodiment 49』 49. The system of any one of embodiments 44-48, wherein the primary vessel further comprises one or more circulation devices for circulating the primary nickel sulfate solution.

[0124] 『Embodiment 50』 50. The system of any one of embodiments 44-49, wherein the secondary vessel further comprises one or more circulation devices for circulating the secondary nickel sulfate solution.

[0125] 『Embodiment 51』 51. The system of embodiment 49 or 50, wherein the one or more circulation devices are selected from a particle separator, one or more pumps, and combinations thereof.

[0126] 『Embodiment 52』 52. The system of any one of embodiments 44-51, wherein the primary container further comprises a dispersion device to minimize bubble formation therein.

[0127] 『Embodiment 53』 53. The system of any one of embodiments 44-52, wherein the secondary container further comprises a dispersion device for minimizing bubble formation therein.

[0128] 『Embodiment 54』 54. The system of embodiment 52 or 53, wherein the dispersion device is selected from a sprinkler, a steamer, a centrifuge, and combinations thereof.

[0129] 『Embodiment 55』 43. The method of any one of embodiments 1-42, wherein elemental nickel is added to the primary reaction vessel and / or the secondary reaction vessel in the form of nickel powder, and the nickel powder is produced by a process selected from thermal spraying, water atomization, carbonyl smelting, and hydrometallurgy.

[0130] 『Embodiment 56』 56. The method of embodiment 55, wherein the step of introducing elemental nickel is performed by direct spraying into the primary container and / or the secondary container.

Claims

1. 1. A method for preparing a nickel sulfate product, comprising the steps of: introducing elemental nickel, sulfuric acid, and water into a primary vessel to form a primary nickel sulfate solution; transferring the primary nickel sulfate solution from the primary vessel to a secondary vessel and adding additional elemental nickel, the secondary vessel recovering unreacted nickel and further reacting the primary nickel sulfate solution with the unreacted nickel to form a secondary nickel sulfate solution; recovering a high purity hydrogen off-gas stream from the primary vessel and / or secondary vessel; and filtering the secondary nickel sulfate solution to recover a nickel sulfate product; A method comprising:

2. 10. The method of claim 1, wherein the high purity hydrogen off-gas stream is used to heat water to produce steam for controlling the process temperature in the primary vessel and / or the secondary vessel.

3. 2. The method of claim 1, wherein oxygen, air, and hydrogen peroxide are not used.

4. 10. The method of claim 1, carried out at a temperature ranging from about 40°C to about 200°C.

5. 10. The method of claim 1, wherein the elemental nickel is in a form selected from pellets, rounds, cathodes, briquettes, powders, and combinations thereof.

6. 2. The method of claim 1, wherein the primary nickel sulfate solution and the secondary nickel sulfate solution are continuously circulated within each vessel.

7. 10. The method of claim 1, wherein the primary container and / or the secondary container are equipped with a dispersing device to minimize foam formation.

8. 8. The method of claim 7, wherein the dispersing device is selected from a sprinkler, a steamer, a centrifuge, and combinations thereof.

9. 10. The method of claim 1, wherein the method is carried out at a pressure above ambient pressure and under an inert atmosphere.

10. 10. The method of claim 9, wherein the inert atmosphere is selected from hydrogen, water vapor, nitrogen, argon, and combinations thereof.

11. The primary nickel sulfate solution has a Ni content in the range of about 70 g / L to about 200 g / L. ２＋ 10. The method of claim 1, wherein the concentration of the soluble solids is 0.5% or more and the pH is in the range of about 0 to about 2.

12. 10. The method of claim 1, wherein the nickel sulfate product has a pH in the range of about 2 to about 4.

13. The pH of the nickel sulfate product was adjusted by adding NaOH, KOH, Ni(OH) ２ 10. The method of claim 1, further characterized by the addition of one or more metal hydroxides selected from:

14. 10. The method of claim 1, wherein the nickel sulfate product is suitable for use without further purification.

15. 1. A system for preparing a nickel sulfate product, comprising: a primary vessel equipped with a settler for mixing elemental nickel, sulfuric acid, and water to form a primary nickel sulfate solution; a secondary vessel equipped with a settler for collecting unreacted nickel particles and the primary nickel sulfate solution and combining the collected nickel particles with additional elemental nickel to form a secondary nickel sulfate solution; an off-gas stream line for recovering high purity hydrogen off-gas from the primary vessel and / or secondary vessel; and a filter for filtering the secondary nickel sulfate solution to recover the nickel sulfate product; A system comprising:

16. 16. The system of claim 15, further characterized in that an off-gas line connects from the head of the primary vessel and / or the head of the secondary vessel to a burner for heating water to produce steam.

17. 17. The system of claim 15 or 16, further comprising a pipe for conveying the generated steam to the bottom of the primary vessel and / or the bottom of the secondary vessel to control the temperature in the primary vessel and / or the secondary vessel.

18. 16. The system of claim 15, wherein the primary vessel and / or the secondary vessel further comprise one or more circulation devices for circulating the primary nickel sulfate solution and / or the secondary nickel sulfate solution.

19. 20. The system of claim 18, wherein the one or more circulation devices are selected from a separator, one or more pumps, and combinations thereof.

20. 16. The system of claim 15, wherein the primary container and / or the secondary container further comprises a dispersion device to minimize foam formation in the primary container and / or the secondary container.

21. 21. The system of claim 20, wherein the dispersion device is selected from a sprinkler, a steamer, a centrifuge, and combinations thereof.

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