Patent Application
20230227938
The present invention relates to a method for manufacturing a high-purity nickel/cobalt mixed solution for cathode materials by using a two-circuit process. More particularly the present invention relates to a method for manufacturing a high-purity Ni/Co mixed solution for cathode materials by using a two-circuit process that skips the crystallization process unlike the conventional three-circuit process of impurity extraction, cobalt (Co) extraction and nickel (Ni) extraction, adopts a two-circuit process to extract cobalt and nickel in a simultaneous manner, and prepare a Ni/Co mixed solution. Accordingly, the efficiency of site utilization can be maximized by reducing the investment cost for the manufacturing process and downsizing mixer-settler facilities. Further, eco-friendly effects such as reducing the consumption of adjuster solutions and cutting down the process costs and the process wastewater production can be realized. This research was supported by Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (2019M3D1A1079306)
Due to the rapid increase in the use of fossil fuels, the demand for alternative energy or clean energy is on the rise. As part of that, research in the field of electrochemical energy is being actively conducted, and, particularly, the need for lithium secondary battery technology is increasing.
A variety of materials are used as cathode materials for lithium secondary batteries, and among others, LiNixCoyMnzO2 (NCM, x+y+z=1) had the highest market share due to its high energy density. Nickel and cobalt are key raw materials in the fabrication of the NCM cathode material.
Meanwhile, the solvent extraction process consisting of three processing steps of extraction, scrubbing and stripping is widely used in the smelting process for nickel and cobalt. In particular, the solvent extraction process of nickel sulfide and cobalt sulfide generally consists of a three-circuit process of impurity extraction, cobalt extraction and nickel extraction.
The traditional three-circuit process is, however, much problematic to require multi-stage mixer-setter tanks with 45 to 60 stages, resulting in a rise of the required size of the facility site and the initial investment costs for the process, and increase the consumption of the adjuster solution for pH adjustment of each mixer-setter tank, the process consumption cost and the process wastewater production. On top of that, an addition of the crystallization process may incur an additional cost of the process and consequently a rise of the unit product cost.
Accordingly, there is an urgent need to develop techniques that may meet the needs for low-cost, eco-friendly lithium secondary batteries and cathode materials thereof that have rapidly increased in recent years. Disclosures such as KR10-2152923 or KR10-1535250 have been proposed as exemplary techniques, but no disclosure has yet been found to present a solution to the above-mentioned problems.
In an attempt to solve the problems, the inventors of the present invention have completed the present invention that prepares a nickel/cobalt (Ni/Co) mixed solution by skipping a crystallization process and adopting a two-circuit process to extract cobalt and nickel in a simultaneous manner rather than using the traditional three-circuit process of impurity extraction, cobalt extraction and nickel extraction, thereby reducing the investment cost for the manufacturing process, downsizing mixer-settler facilities to maximize the efficiency of site utilization, and realizing eco-friendly effects, such as reducing the consumption of adjuster solutions and cutting down the process costs and the process wastewater production.
It is an object of the present invention to provide a method for manufacturing a high-purity nickel/cobalt mixed solution for a cathode material by using a two-circuit process that involves extracting nickel and cobalt in a simultaneous manner using a two-circuit process to prepare a nickel/cobalt mixed solution, thereby removing the problem with the traditional three-circuit process that requires multi-stage mixer-setter tanks with 45 to 60 stages and leads to an increase in the scale of the facility site and the initial investment cost for the process.
It is another object of the present invention to provide a method for manufacturing a high-purity nickel/cobalt mixed solution for a cathode material by using a two-circuit process that skips the crystallization process and thereby solves the problem of increasing the unit product cost due to the additional process cost.
It is still another object of the present invention to provide a method for manufacturing a high-purity nickel/cobalt mixed solution for a cathode material by using a two-circuit process that prevents an increase in the consumption of the adjuster solution in each mixer-setter tank for pH adjustment and the process costs and realizes eco-friendly effects, such as cutting down the production of the process wastewater.
All the above and other objects of the present invention can be achieved by the present invention given in the following description.
In one aspect of the present invention, there is provided a method for manufacturing a high-purity nickel/cobalt mixed solution for cathode materials by using a two-circuit process, the method comprising: (a) a first circuit extraction process of extracting impurities other than magnesium (Mg) in an organic phase from a sulfide containing nickel, cobalt and magnesium using a first extraction agent at a given value of pH; (b) a first circuit scrubbing process of stirring the extracted organic phase along with distilled water to recover the extracted nickel and cobalt in an aqueous phase; (c) a first circuit stripping process of recovering impurities contained in the first extraction agent in an aqueous phase; (d) a second circuit extraction process of saponifying a second extraction agent for separation of magnesium of the first circuit process and extracting nickel, cobalt and manganese in an organic phase; (e) a second circuit scrubbing process of stirring the organic phase from the second circuit extraction process along with distilled water and recovering the extracted magnesium in an aqueous phase; and (f) a second circuit stripping process of recovering the extracted nickel and cobalt in an aqueous phase and productizing into a mixed liquid form.
In an embodiment, the first circuit extraction process may be performed at pH 3.4 to 3.6, with an organic/aqueous (O/A) ratio being 1.7 to 1.9.
In an embodiment, the first circuit scrubbing process may be performed at pH 2.9 to 3.1, with an organic/aqueous (O/A) ratio being 4.9 to 5.1.
In an embodiment, the first circuit stripping process may be performed using 13 to 17 wt. % of sulfuric acid (H2SO4) in an aqueous phase, with an organic/aqueous (O/A) ratio being 4.9 to 5.1.
In an embodiment, the second circuit extraction process may be performed at pH 6.2 to 6.4, with an organic/aqueous (O/A) ratio being 3.7 to 3.8.
In an embodiment, the second circuit scrubbing process may be performed at pH 6.1 to 6.3, with an organic/aqueous (O/A) ratio being 4.9 to 5.1.
In an embodiment, the second circuit stripping process may be performed using 25 to 35 wt. % of sulfuric acid (H2SO4) in an aqueous phase, with an organic/aqueous (O/A) ratio being 4.9 to 5.1.
In an embodiment, the second circuit stripping process may be performed at a process temperature of 55 to 65° C.
In an embodiment, the first extraction agent may be bis(2-ethylhexyl)phosphate (D2EHPA, di-2-ethylhexyl-phosphoric acid), and the second extraction agent may be versatic acid (VA-10, Versatic Acid-10).
The method for manufacturing a high-purity nickel/cobalt mixed solution for cathode materials by using a two circuit process according to the present invention skips the crystallization process unlike the conventional three-circuit process of impurity extraction, cobalt (Co) extraction and nickel (Ni) extraction and adopts a two-circuit process to extract cobalt and nickel in a simultaneous manner and prepare a nickel/cobalt mixed solution, thereby reducing the investment cost for the manufacturing process, downsizing mixer-settler facilities to maximize the efficiency of site utilization, and realizing eco-friendly effects, such as reducing the consumption of adjuster solutions and cutting down the process costs and the production of the process wastewater.
Hereinafter, embodiments of the present invention will be described in further detail with reference to the accompanying drawings. The technology disclosed in the present invention is not limited to the embodiments described herein and may be embodied in other forms. But, the embodiments disclosed herein are provided so that the disclosed content can be thorough and complete, and so that the spirit of the present invention can be readily conveyed to those skilled in the art. In the drawings, the dimensions such as width and thickness of the components are slightly enlarged in order to clearly express the components of each device.
In addition, although only some of the components are illustrated for convenience of description, those skilled in the art will be able to easily grasp the remaining parts. In the description of the drawings as a whole, it has been described from an observer's point of view. When an element is referred to as being positioned on or under another element, it means that the element is positioned directly on or under another element, or any other element exists between these two elements.
In addition, those of ordinary skill in the art will be able to implement of the spirit of the present invention in various other forms within the scope not departing from the technical spirit of the present invention. In the plurality of drawings, the same reference numerals are assigned to the elements that are substantially the same as each other.
The singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “has” used herein specify the presence of stated feature, number, step, operation, component, element, part, or a combination thereof but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, elements, parts, or combinations thereof.
In addition, in performing the method or the manufacturing method, each process constituting the method may occur differently from the specified order unless the specific order is clearly described in context. In other words, each process may occur in the same order as specified or may be performed substantially in a simultaneous manner or in the reverse order.
Hereinafter, the present invention will be described in further detail.
Referring to
The solvent extraction process of smelting nickel and cobalt separates elements of interest from a mixed solution containing impurities using the difference between separation factors of solvent extraction agents. This process may consist of three processing steps of extraction, scrubbing and stripping and optionally include saponification.
The solvent extraction process uses the distribution coefficient that is the ratio of concentrations of each metal ion in the organic phase (a solvent extraction agent, extractant) and the aqueous phase at thermodynamic equilibrium. The distribution coefficient is different for each metal, so the separation factor that is in proportion to the distribution coefficient can be used to selectively purify a metal of interest in a mixed solution containing a mixture of the metal of interest and impurities.
In the solvent extraction process, the pH is altered to modify the distribution coefficient and the separation factor. The pH adjustment is achieved using an acidic or alkaline pH adjuster, and the consumption of the pH adjuster solution can be minimized through reduction of the degree of pH adjustment.
Using the two-circuit process of the present invention, it is possible to overcome the limitation of the prior inventions, thus downsizing the mixer-setter facilities to maximize the efficiency of site utilization and realizing eco-friendly effects, such as reducing the consumption of adjuster solutions and cutting down the process costs and the production of the process wastewater.
Method for Manufacturing High-Purity Ni/Co Mixed Solution for Cathode Material by Two-Circuit Process
As one aspect of the present invention, the preparation method for a high-purity nickel/cobalt mixed solution for cathode materials by using a two-circuit process consists of a first circuit extraction process, a first circuit scrubbing process, a first circuit stripping process, a second circuit extraction process, a second circuit scrubbing process, and a second circuit stripping process.
Referring to
The second circuit process S200 includes a second circuit extraction process S210 of saponifying a second extraction agent for separation of magnesium of the first circuit process and extracting nickel, cobalt and manganese in an organic phase; a second circuit scrubbing process S220 of stirring the organic phase from the second circuit extraction process along with distilled water and recovering the extracted magnesium in an aqueous phase; and a second circuit stripping process S230 of recovering the extracted nickel and cobalt in an aqueous phase and productizing into a mixed liquid form. A detailed description will be given as follows.
First Circuit Process
The first circuit process S100 is conducted for the purpose of isolating impurities other than magnesium from a feed solution in order to prepare a high-purity Ni/Co mixed solution for cathode materials according to an embodiment of the present invention. Further, it consists of the first circuit extraction process S110, the first circuit scrubbing process S120, and the first circuit stripping process S130.
The first circuit extraction process S110 is for extracting impurities other than magnesium in an organic phase from a sulfide containing nickel, cobalt and magnesium in the presence of a first extraction agent at a given value of pH.
The first circuit extraction process may be performed at pH 3.4 to 3.6 as adjusted by using 35 to 45 wt. % of sodium hydroxide (NaOH), preferably at pH 3.45 to 3.55 as adjusted by using 37 to 43 wt. % of sodium hydroxide (NaOH). The pH value below the range makes it difficult to extract all the impurity elements and reduces the extraction percentages of impurity metals to eventually increase the required number of extraction stages; whereas the pH value above the range causes unintended extraction of the metals of interest in a large quantity, increasing the required number of scrubbing stages in the first circuit scrubbing step.
The first circuit extraction process may be performed at an organic/aqueous (O/A) ratio of 1.7 to 1.9, preferably 1.75 to 1.85. The O/A ratio below the range increases the number of stages required for the removal of impurity elements, especially copper (Cu); whereas the O/A ratio above the range results in consuming the extraction agent in an excessive amount relative to the impurity elements.
The first extraction agent is diluted with a diluent and acts as an organic solvent. Examples of the first extraction agent may include alkyl phosphonic acid esters, such as bis(2-ethylhexyl)phosphate (D2EHPA), or mono-2-ethylhexyl (2-ethylhexyl)phosphonate (common name, PC-88 A). Preferably, the first extraction agent may be bis(2-ethylhexyl)phosphate (D2EHPA, di-2-ethylhexyl-phosphoric acid). On the other hand, the diluent is not specifically limited as long as it is capable of dissolving the extraction agent. Examples of the diluent may include naphthenic solvents or aromatic solvents.
The first circuit scrubbing process S120 is for stirring the extracted organic phase with distilled water to transfer the extracted nickel and cobalt partly loaded along with the impurities on the organic phase back into an aqueous phase.
The first circuit scrubbing process may be performed at pH 2.9 to 3.1 as adjusted by using 25 to 35 wt. % of sulfuric acid (H2SO4), preferably at pH 2.95 to 3.05 as adjusted by using 27 to 32 wt. % of sulfuric acid (H2SO4). The pH value below the range poses a risk of recovering the extracted impurity elements into the aqueous phase and increases the required number of stages; whereas the pH value above the range makes it difficult to completely scrub the metal of interest.
The first circuit scrubbing process may be performed at an organic/aqueous (O/A) ratio of 4.9 to 5.1, preferably 4.95 to 5.05. The O/A ratio below the range increases the production of the process wastewater; whereas the O/A ratio above the range makes it difficult to completely scrub the metal of interest.
The first circuit stripping process S130 is for recovering the impurities loaded on the first extraction agent into an aqueous phase in order for the first extraction agent to be recycled to the extraction operation, thereby making the operation of the process smooth in the later step of reintroducing the first extraction agent to the first circuit extraction process.
The first circuit stripping process may use 13 to 17 wt. % of sulfuric acid (H2SO4) in the aqueous phase, preferably 14 to 16 wt. % of sulfuric acid (H2SO4) in the aqueous phase. The concentration of the sulfuric acid below the range reduces the stripping percentage and increases the required number of stripping stages; whereas the concentration of the sulfuric acid above the range poses a risk of forming precipitates of calcium sulfate to cause problems in the process.
The first circuit stripping process may be performed at an organic/aqueous (O/A) ratio of 4.9 to 5.1, preferably 4.95 to 5.05. The O/A ratio out of the range reduces the overall stripping percentages and incurs formation of precipitates to reduce the concentration of the sulfuric acid, causing problems in the process.
Second Circuit Process
Using the aqueous phase from the first circuit extraction process containing Ni, Co, Mn, and Mg removed of impurities other than Mg as a feed solution, the second circuit process S200 is performed for the purpose of isolating Mg from Ni, Co and Mn in order to prepare a high-purity Ni/Co mixed solution for cathode materials according to an embodiment of the present invention.
The second circuit extraction process S210 is for saponifying a second extraction agent for separation of magnesium of the first circuit process S100 and extracting nickel, cobalt and manganese in an organic phase.
The second circuit extraction process may be performed at pH 6.2 to 6.4 as adjusted by using 35 to 45 wt. % of sodium hydroxide (NaOH), preferably at pH 6.25 to 6.35 as adjusted by using 37 to 43 wt. % of sodium hydroxide (NaOH). The pH value below the range makes it difficult to completely extract the metals of interest; whereas the pH value above the range increases the risk of incurring unintended extraction of magnesium. On top of this, the sodium hydroxide may be used to adjust the pH of the extraction agent.
The second circuit extraction process may be performed at an organic/aqueous (O/A) ratio of 3.7 to 3.8, preferably 3.73 to 3.76. The O/A ratio below the range increases the number of stages necessary to the extraction of the metals of interest, especially cobalt (Co); whereas the O/A ratio above the range results in consuming the extraction agent in an excessive amount relative to the metals of interest.
The second extraction agent may be versatic acid (VA10, Versatic Acid-10), which is characterized by high selectivity for nickel (Ni) extraction through saponification.
The second circuit scrubbing process S220 is for stirring the organic phase from the second circuit extraction process along with distilled water and transferring the extracted magnesium back to the aqueous phase.
The second circuit scrubbing process may be performed at pH 6.1 to 6.3, preferably at pH 6.15 to 6.25. This process is conducted at the initial pH of around 6.2 that is provided by adding no adjuster solution. The pH value out of the range causes the metals of interest to be scrubbed again.
The second circuit scrubbing process may be performed at an organic/aqueous (O/A) ratio of 4.9 to 5.1, preferably 4.95 to 5.05. The O/A ratio below the range increases the production of the process wastewater; whereas the O/A ratio above the range makes it difficult to completely scrub magnesium (Mg).
The second circuit stripping process S230 is not only for recovering the organic phase containing the extracted metals of interest, Ni and Co, to the aqueous phase, but for conducting concentration through adjustment of the O/A ratio to achieve productization into a mixed liquid form. In addition, this process is also performed for the recycling of the second extraction agent through the recovery of the elements loaded on the second extraction agent.
The second circuit stripping process may use 25 to 35 wt. % of sulfuric acid (H2SO4) with an organic/aqueous (O/A) ratio of 4.9 to 5.1. Within the ranges, it is possible to prevent a reduction of stripping percentages and make the process operations smooth.
In the second circuit stripping process, the process temperature may be 55 to 65° C., preferably 57 to 62° C. The process temperature within the defined range has an effect to reduce the formation of reddish brown precipitates that may occur during the process at the room temperature.
As described above, the method for manufacturing a high-purity Ni/Co mixed solution for cathode materials by using a two-circuit process according to an embodiment of the present invention skips a crystallization process unlike the conventional three-circuit process of impurity extraction, cobalt (Co) extraction and nickel (Ni) extraction and adopts a two-circuit process to extract cobalt and nickel in a simultaneous manner and produce a Ni/Co mixed solution, so it is advantageously possible to reduce the investment cost for the manufacturing process, downsize mixer-settler facilities, thus maximizing the efficiency of site utilization, and realize eco-friendly effects, such as reducing the consumption of adjuster solutions and cutting down the process costs and the process wastewater production.
Hereinafter, a further detailed description will be given as to the configurations and functions of the present invention with reference to the preferred embodiments of the present invention, which are given for illustration of the preferable examples of the present invention and should be construed to not limit the scope of the present invention.
Contents not described in this disclosure can be technically inferred sufficiently by those skilled in the art and the description thereof will be omitted.
In the first circuit extraction process, D2EHPA as an extraction agent was diluted with ISD-159 to a concentration of 21% in order to extract impurities such as Fe, Cu, Ca, Zn, and Al other than Mg in the organic phase. The pH was adjusted to approximately 3.5 using 40 wt. % of NaOH as a pH adjuster solution. In this regard, the process had an organic/aqueous (O/A) ratio of approximately 1.8 and consisted of four stages, i.e., three theoretical stages as determined by the McCabe-Thiele diagram plus one experimental extra stage.
Subsequently, in the first circuit scrubbing process, the organic phase containing the metals of interest (Ni and Co) extracted in the first circuit extraction process was stirred along with distilled water to recover the metals of interest in an aqueous phase. The pH was adjusted to approximately 3 using 30 wt. % of sulfuric acid as a pH adjuster solution. The process had an organic/aqueous (O/A) ratio of approximately 5 and consisted of two stages, i.e., one theoretical stage as determined by the McCabe-Thiele diagram plus one experimental extra stage.
In the first circuit stripping process, impurity elements contained in the extraction agent were recovered in the aqueous phase in order to allow the extraction agent to be recycled later. The stripping process used 15 wt. % of sulfuric acid for the aqueous phase and consisted of two stages with an O/A ratio of 5.
In the second circuit extraction process, VA-10 as an extraction agent was diluted with ISD-159 to a concentration of 40% and saponified to extract Ni, Co, and Mn in the organic phase, in order to isolate Mg that was not separated in the first circuit process. The pH was adjusted to approximately 6.3 using 40 wt. % of NaOH as a pH adjuster solution. The process had an organic/aqueous (O/A) ratio of approximately 3.75 and consisted of four stages, i.e., three theoretical stages as determined by the McCabe-Thiele diagram plus one experimental extra stage.
Subsequently, in the second circuit scrubbing process, the organic phase after extraction was stirred along with distilled water to recover Mg extracted during the second circuit extraction process into the aqueous phase. The process was performed without using any pH adjuster solution and hence operated at the initial pH of 6.2. The process had an organic/aqueous (O/A) ratio of approximately 5 and consisted of two theoretical stages as determined by the McCabe-Thiele diagram.
In the second circuit stripping process, the extracted metals of interest were recovered to the aqueous phase and productized into a mixed liquid form. The stripping process used 30 wt. % of sulfuric acid for the aqueous phase and consisted of one to two stages with an O/A ratio of around 5. In this regard, the process temperature was about 60° C. The final product thus obtained was the high-purity nickel/cobalt mixed solution for cathode materials prepared by a two-circuit process according to an embodiment of the present invention.
The procedures were performed in the same manner as described in Example 1, excepting that the first circuit stripping process had an O/A ratio of around 10, to prepare a high-purity nickel/cobalt mixed solution for cathode materials.
The high-purity nickel/cobalt mixed solution for cathode materials using a two-circuit process was prepared according to an embodiment of the present invention as described above. The results, including the yields, are presented in Tables 1, 2 and 3 and
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As described above, the method for manufacturing a high-purity nickel/cobalt mixed solution for cathode materials by using a two-circuit process that skips the crystallization process unlike the conventional three-circuit process of impurity extraction, cobalt (Co) extraction and nickel (Ni) extraction and adopts a two-circuit process to extract cobalt and nickel in a simultaneous manner and prepare a nickel/cobalt mixed solution, thereby reducing the investment cost for the manufacturing process, downsizing mixer-settler facilities to maximize the efficiency of site utilization, and realizing eco-friendly effects, such as reducing the consumption of adjuster solutions and cutting down the process costs and the production of process wastewater.
Although the exemplary embodiments of the present invention have been described with reference to limited embodiments and drawings, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art.
Accordingly, the scope of the present invention should not be defined by these embodiments but by the following claims and equivalents to the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0008271 | Jan 2022 | KR | national |
