DESC:FORM 2

THE PATENTS ACT, 1970

(39 of 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION

[See Section 10 and Rule 13]

TITLE:

“A METHOD FOR RECOVERY OF METALS FROM CATHODE MATERIAL OF SPENT LITHIUM TITANIUM OXIDE BATTERY”

APPLICANT:

ATTERO RECYCLING PVT. LTD.
a company incorporated under Indian companies Act, 1956,
having address at
173, Raipur Industrial Area, Bhagwanpur, Roorkee, Haridwar Uttarakhand 247661, India

PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it is to be performed:
FIELD OF THE INVENTION
The present invention relates to the field of recycling of spent batteries. More particularly, the present invention relates to an environment friendly and commercially feasible method for recovery of metals from cathode material of spent lithium titanium oxide (LTO) battery.

BACKGROUND OF THE INVENTION
A lithium-titanate or lithium titanium oxide battery is an improved version of lithium ion battery (LiB) that comprises of lithium-titanate nanocrystals instead of carbon on the surface of the anode. Lithium-titanate nanocrystals allow the anode to gain a surface area of around 100 square meters per gram against 3 square meters per gram for carbon that permits the electrons to enter and exit the anode quickly. The ability to donate or accept electrons in the electrolytic solutions of lithium ions with titanium oxide allows for fast charging capacity. Lithium-titanate battery offers fast charging, long battery life and low-temperature resistance. Lithium-titanate batteries can provide a high charging and discharging rate, making them worthwhile for applications requiring quick charging and a high current. Another benefit of lithium-titanate batteries is their increased resistance to high temperatures.
However, one of the drawback of the lithium-titanate batteries is the high cost of production. Further, when the lithium-titanate batteries are used over a period of time, a small amount of gas is produced within the battery pack. Even though there are enough of batteries, collection of these spent batteries is one of the biggest challenge for recycling industry. With different recycling processes, each of the elements including lithium, copper, aluminum, cobalt, nickel and manganese can be extracted in different forms. The degree of recovery of different elements vary with recycling process and chemical compositions of battery.
CN111254294 discloses a method for selectively extracting lithium from waste lithium ion battery powder and recovering manganese dioxide through electrolytic separation. The method comprises the steps as follows: concentrated sulfuric acid is added to waste lithium ion battery powder and the mixture is fully stirred and mixed; the acid stirred-and-mixed battery powder is placed in an electric furnace for being roasted at a certain temperature; the roasted battery powder is mechanically stirred and leached with pure water at a predetermined temperature; slurry is subjected to liquid-solid separation, filter residue is fed to a wet method nickel cobalt-manganese recovery system, and impurities of a lithium-containing leaching solution are removed by sulfide precipitation and oxidation neutralization precipitation; a lithium-containing purification solution electrolyzes to produce manganese dioxide powder. However, the method is inefficient and complex where the selective extraction is done by using chemicals such as treatment with concentrated sulfuric acid and sulphide precipitation, which is considered to be harmful.
CN115986248 discloses about a lithium titanate battery recovery processing method. The method comprises the following steps: controlling the discharge voltage of the waste lithium titanate battery, and disassembling the waste lithium titanate battery to obtain lithium-deficient waste lithium titanate; and supplementing the waste lithium titanate in the lithium-deficient state into a lithium source, a sodium source or a potassium source, uniformly mixing, and roasting to obtain the regenerated titanate electrode material. However, the method is tedious and expensive as it involves two stage roasting upto the temperature of 900°C with lithium source.
US10156017 discloses a method of simultaneously recovering cobalt and manganese from lithium based battery. The method includes roasting that is performed in presence of inert gas at a temperature of 500°C, multistage leaching with sulphuric acid and peroxide at high temperature. However, the method is complex as the PC-88A solvent is employed to concentrate before electrolysis and also, hydrometallurgical process is done with solvent extraction. Hence, the method is also non-eco-friendly.
WO202345331 discloses about a method for selectively recovering valuable metal in waste lithium battery. The method comprises the following steps of: adding a sulphur containing compound to a waste lithium battery for roasting and water leaching to obtain a lithium carbonate solution and filter residues; adding sulfuric acid and an iron containing compound to the filter residues for leaching, performing solid-liquid separation, and taking a solid phase to obtain manganese dioxide and graphite slag; taking a liquid phase obtained after the solid-liquid separation for extraction and reverse extraction to obtain a nickel-cobalt sulfate solution and a manganese sulfate solution. However, the method provides impure products and multiple process steps with multiple chemical addition.
Ordonez et al, in Renewable and sustainable energy reviews 60 (2016) 195-205; doi: http://dx.doi.org/10.1016/j.rser.2015.12.363, is a review article that discloses about various processes and technologies for the recycling and recovery of spent lithium-ion batteries. However, further research is needed to provide an efficient method of recycling.
Barik et al, in Waste Management (2015); doi: http://dx.doi.org/10.1016/j.wasman.2015.11.004, discloses an innovative approach to recover the metal values from spent lithium-ion batteries that involves time-consuming processes. However, the method requires further studies and method to provide optimum conditions about the process.
In view of above, the state of art discloses chemical, mechanical, hydrometallurgical or pyrometallurgical process for recovering valuable metals from spent battery. Mechanical process involves dismantling of the battery and separation of different components. Hydrometallurgical process includes leaching, precipitation, refining and other processes. However, high energy consumption and emission of gas are the major challenges for pyrometallurgical based recycling processes. Some other challenges include impure products obtained, expensive and inefficient method, and use of harsh chemicals that are harmful for nature, less recovery rate and non-feasibility at large scale.
Therefore, there is a need to explore an easy to operate, environment friendly, commercially feasible and economically viable method for recycling of metals from lithium battery with better recovery and purity.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a method for recovery of metals from spent lithium titanium oxide battery.
Another object of the present invention is to provide a method for recovery of metals from cathode material of spent lithium titanium oxide (LTO) battery.
Yet another object of the present invention is to provide an environment friendly and commercially feasible method for recovery of metals from spent lithium titanium oxide battery.
Yet another object of the present invention is to provide a simple and easy to operate method for recovery of metals from spent lithium titanium oxide battery.
Still another object of the present invention is to provide an efficient method for recovery of metals from spent lithium titanium oxide battery that recovers metals with high purity.

SUMMARY OF THE INVENTION
The present invention relates to an environment friendly and commercially feasible method for recovery of metals from cathode material of spent lithium-titanium-oxide (LTO) battery that involves processes of roasting, sonication, filtration, leaching, precipitation and electrolysis.
In an embodiment, the present invention provides a method for recovery of metals from spent lithium titanium oxide (LTO) battery, comprising the steps of: (a) roasting cathode material of spent LTO batteries for a duration followed by cooling at room temperature to obtain a roasted mass; (b) sonicating the roasted mass obtained in step (a) in water to detach the black mass from aluminum foil to obtain a slurry; (c) filtering the slurry after removing aluminum foil in step (b) to obtain a black mass and a filtrate; (d) leaching the black mass obtained in step (c) with a leaching solution by maintaining a pH range under agitation for 4-6 hours at a pulp density of 20-30% (w/v) to obtain a leach liquor; (e) precipitating the leach liquor obtained in step (d) with a precipitating agent at a pH in a range of 5-6 under agitation for 1-3 hour followed by filtration to obtain a purified liquor and an aluminum carbonate cake; (f) feeding the purified liquor obtained in step (e) into an electrolytic cell to obtain a spent electrolyte and a plurality of recovered metals; and (g) recovering lithium from the spent electrolyte obtained in step (f).
Here, said roasting in step (a) is performed at a temperature range of 300-500°C for said duration of 2-4 hours and sonication in step (b) is achieved with a power capacity of 200-300 watt and operational frequency ranging from 25-35 kHz for 3-5 minutes; said electrolysis in step (f) is done by passing a current of 6 ampere at a temperature of 90-100°C and a current density of 200 A/m2; and said plurality of recovered metals in step (f) includes cobalt (Co) and electrolytic manganese dioxide (EMD).
The present invention relates to a simple, easy to operate and environmentally friendly method of recovery of 97-98% of cobalt and manganese with % purity ranging from 98.5-99.9%. Further, the present invention provides the limited use of chemicals wherein the filtrate obtained after obtaining the black mass is reemployed for the next batch.
The above objects and advantages of the present invention will become apparent from the hereinafter set forth brief description of the drawings, detailed description of the invention, and claims appended herewith.

BRIEF DESCRIPTION OF THE DRAWINGS
An understanding of the method for recovery of metals from spent lithium titanium oxide battery of the present invention may be obtained by reference to the following drawings:
Figure 1 is a schematic representation of a method for recovery of metals from spent lithium titanium oxide battery, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art.
The present invention now will be described hereinafter with reference to the detailed description, in which some, but not all embodiments of the invention are indicated. Indeed, the invention may be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. The present invention is described fully herein with non-limiting embodiments and exemplary experimentation.
The present invention provides an environment friendly and commercially feasible method for recovery of metals from cathode material of spent lithium-titanium-oxide (LTO) battery that involves processes of roasting, sonication, filtration, leaching, precipitation and electrolysis.
In a preferred embodiment, the present invention provides a method for recovery of metals from spent lithium titanium oxide (LTO) battery, comprising the steps of: (a) roasting cathode material of spent LTO batteries for a duration followed by cooling at room temperature to obtain a roasted mass; (b) sonicating the roasted mass obtained in step (a) in water to detach the black mass from aluminum foil to obtain a slurry; (c) filtering the slurry after removing aluminum foil in step (b) to obtain a black mass and a filtrate; (d) leaching the black mass obtained in step (c) with a leaching solution by maintaining a pH range under agitation for 4-6 hours at a pulp density of 20-30% (w/v) to obtain a leach liquor; (e) precipitating the leach liquor obtained in step (d) with a precipitating agent at a pH in a range of 5-6 under agitation for 1-3 hour followed by filtration to obtain a purified liquor and an aluminum carbonate cake; (f) feeding the purified liquor obtained in step (e) into an electrolytic cell to obtain a spent electrolyte and a plurality of recovered metals; and (g) recovering lithium from the spent electrolyte obtained in step (f).
Here, said roasting in step (a) is performed at a temperature range of 300-500°C for said duration of 2-4 hours and sonication in step (b) is achieved with a power capacity of 200-300 watt and operational frequency ranging from 25-35 kHz for 3-5 minutes; said electrolysis in step (f) is done by passing a current of 6 ampere at a temperature of 90-100°C and a current density of 200 A/m2; and said plurality of recovered metals in step (f) includes cobalt (Co) and electrolytic manganese dioxide (EMD).
Further, said filtrate obtained in step (c) is again employed in next batch of recovery of metals from spent lithium titanium oxide battery; said leaching solution in step (d) is a mixture of 15-20% v/v of sulphuric acid and 4-8% w/v of hydrogen peroxide; said pH in step (d) is in a range of 0.5-1.0; and said precipitating agent in step (e) is a solution including 25% w/v of soda ash, calcium hydroxide, sodium hydroxides or ammonium hydroxide.
As the filtrate obtained in step (c) contains water with traces of lithum, additional water consumption gets avoided and it prevents the loss of lithium in short for better recovery of lithium, maintains water balance and dust free environment. Further, in step (c), press filter, rotary drum filter, centrifuge or belt filter is used for filtration.
The sulphuric acid used is having assay above 98% wt/wt and added to maintain the pH. The concentration of acid in the slurry is different from the assay.
Additionally, said electrolytic cell in step (f) includes two lead sheets as anode and one sheet of stainless steel of SS-316 grade as cathode and said electrolysis in step (f) is performed for 6-20 hours.
Moreover, said method of the present invention recovers 97-98% of cobalt metal with % purity from 99.8-99.9%. Further, method recovers 97-98% of EMD through the electrolysis with % purity ranging from 98.5-99%. The spent electrolyte obtained in step (g) is a solution free of cobalt and manganese that contains lithium metal in a range of 2.97-3.1 g/L.
Referring to Figure 1, a schematic representation of a method for recovery of metals from spent lithium titanium oxide battery, is illustrated. The method involves the step by step processes that includes processes of roasting, sonication, filtration, leaching, precipitation and electrolysis.

EXAMPLE 1
For Experimentation Data
A method for recovery of metals from cathode material of spent lithium titanium oxide battery
Batch 1
0.150 Kg cathode material was roasted at 400°C for 2 hours. The roasted cathode material was allowed to cool at room temperature and sonicated with 1.5 L of water for 5 minutes. 0.041 Kg of Al-foil was collected and the slurry was filtered to get the black mass (0.1 Kg). The black mass was leached by agitating with 0.5 L of water, 0.05 L of H2SO4, and 0.04 L of H2O2 for 4 hours by maintaining pH in the range of 0.8-1. Next, 0.500 L of the leach liquor was agitated with 0.048 L of soda ash solution (25%, w/v) to precipitate the aluminum in the pH range of 5.5-6. The slurry was filtered to get the purified liquor (0.480 L) and the aluminum cake (0.07 Kg). The analysis of input for chemical process, process liquor and after impurity removal of the black mass, leach liquor and purified liquor are presented in Table 1. The purified liquor (0.480 L) was fed into electrolysis cell (containing two lead sheets as the anode and one SS-316 as the cathode) and a current of 6 amperes was passed at a temperature ranging from 90-100°C for 6 hours. After 6 hours of electrolysis process, 0.006 Kg of cobalt metal and 0.038 Kg of MnO2 (EMD) were recovered. In case of MnO2, impurities to subtract from 100 to get purity and only major impurity is lead which is around 1-1.5 %. The analysis of cobalt metal, MnO2 (EMD) and spent electrolyte are presented in Table 2.
Table 1: Analysis of the black mass, leach liquor & purified liquor of batch 1
Sample Unit Elements
Co Li Al Mn Fe
Black mass % 6.7 1.6 2 27 0.3
Leach liquor g/L 13.4 3.2 4 54 0.6
Purified liquor g/L 13.2 3.1 0.01 53.8 0.001

Table 2: Analysis of cobalt metal, MnO2 (EMD) & spent electrolyte of batch 1
Sample Unit Co Mn Al Pb Li Fe
Co metal % 99.9 0.001 0.0001 0.0005 0.0001 0.0005
MnO2 % 0.015 62.01 0.0001 1.01 0.0001 0.0001
Spent electrolyte g/L 0.6 3 0.0001 0.0001 3.1 0.0001

Batch 2
0.450 Kg cathode material was roasted at 400°C for 2 hours. The roasted cathode material was allowed to cool at room temperature and sonicated with 3.5 L of water for 5 minutes. 0.12 Kg of Al-foil was collected and the slurry was filtered to get the black mass (0.3 Kg). The black mass was leached by agitating with 1.5 L of water, 0.15 L of H2SO4, and 0.12 L of H2O2 for 5 hours by maintaining pH in the range of 0.8-1. Next, 1500 L of the obtained leach liquor was agitated with 0.15 L of soda ash solution (25% w/v) to precipitate aluminum in the pH range of 5.5-6. The slurry was filtered to get the purified liquor (1.5 L) and the aluminum cake (0.23 Kg). The analysis of the black mass, leach liquor, and purified liquor are presented in Table 3. The purified liquor (1.5 L) was fed into electrolysis cell (containing two lead sheets as the anode and one SS-316 as the cathode) and a current of 6 amperes was passed at 90-100°C for 20 hours. After 20 hours of electrolysis process, 0.018 Kg of cobalt metal and 0.12 Kg of MnO2 (EMD) were recovered. The analysis of cobalt metal, MnO2 (EMD) and spent electrolyte are presented in Table 4.
Table 3: Analysis of the black mass, leach liquor & purified liquor of batch 2
Sample Unit Elements
Co Li Al Mn Fe
Black mass % 6.7 1.6 2 27 0.3
Leach liquor g/L 13.4 3.1 3.9 54.2 0.53
Purified liquor g/L 13.1 3 0.01 53.9 0.001

Table 4: Analysis of cobalt metal, MnO2 (EMD) & spent electrolyte of batch 2
Sample Unit Co Mn Al Pb Li Fe
Co metal % 99.90 0.001 0.0001 0.0005 0.0001 0.0005
MnO2 % 0.011 62.32 0.0001 1.21 0.0001 0.0001
Spent electrolyte g/L 0.58 2.9 0.0001 0.0001 2.97 0.0001

Batch 3
0.450 Kg cathode material was roasted at 400°C for 2 hours. The roasted cathode material was allowed to cool at room temperature and sonicated with 3.5 L of water for 5 minutes. 0.11 Kg of Al-foil was collected and the slurry was filtered to get the black mass (0.28 Kg). The black mass was leached by agitating with 1.5 L of water, 0.15 L of H2SO4, and 0.12 L of H2O2 for 6 hours by maintaining pH in the range of 0.8-1. Next, the leach liquor (1.480 L) was agitated with 0.15 L of soda ash solution (25% w/v) to precipitate aluminum at a pH ranging from 5.5-6. The slurry was filtered to get the purified liquor (1.5 L) and the aluminum cake (0.2 Kg). The analysis of the black mass, leach liquor, and purified liquor are presented in Table 5. The purified liquor (1.5 L) was fed into electrolysis cell (containing two lead sheets as the anode and one SS-316 as the cathode) and a current of 6 amperes was passed at 90-100°C for 19 hours. After 19 hours of electrowinning process, 0.019 Kg of cobalt metal and 0.13 Kg of MnO2 (EMD) were recovered. The analysis of cobalt metal, MnO2 (EMD) and spent electrolyte are presented in Table 6.
Table 5: Analysis of the black mass, leach liquor & purified liquor of batch 3
Sample Unit Elements
Co Li Al Mn Fe
Black mass % 6.7 1.6 2 27 0.3
Leach liquor g/L 13.2 3.22 3.95 54.1 0.51
Purified liquor g/L 13.1 3 0.01 53.9 0.001

Table 6: Analysis of cobalt metal, MnO2 (EMD) & spent electrolyte of batch 3
Sample Unit Co Mn Al Pb Li Fe
Co metal % 99.89 0.001 0.0001 0.0005 0.0001 0.0005
MnO2 % 0.011 62.29 0.0001 1.18 0.0001 0.0001
Spent electrolyte g/L 0.61 2.32 0.0001 0.0001 3.1 0.0001

Therefore, the present invention provides a simple, easy to operate, environment friendly and commercially feasible method for recovery of metals from cathode material of spent lithium-titanium-oxide (LTO) battery.
Many modifications and other embodiments of the invention set forth herein will readily occur to one skilled in the art to which the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
,CLAIMS:CLAIMS

We claim:
1. A method for recovery of metals from spent lithium titanium oxide (LTO) battery, comprising the steps of:
(a) roasting cathode material of spent LTO batteries for a duration followed by cooling at room temperature to obtain a roasted mass;
(b) sonicating the roasted mass obtained in step (a) in water to detach the black mass from aluminum foil to obtain a slurry;
(c) filtering the slurry after removing aluminum foil in step (b) to obtain a black mass and a filtrate;
(d) leaching the black mass obtained in step (c) with a leaching solution by maintaining a pH range under agitation for 4-6 hours at a pulp density of 20-30% (w/v) to obtain a leach liquor;
(e) precipitating the leach liquor obtained in step (d) with a precipitating agent at a pH in a range of 5-6 under agitation for 1-3 hour followed by filtration to obtain a purified liquor and an aluminum carbonate cake;
(f) feeding the purified liquor obtained in step (e) into an electrolytic cell to obtain a spent electrolyte and recover a plurality of metals through electrolysis; and
(g) recovering lithium from the spent electrolyte obtained in step (f);
wherein,
said filtrate obtained in step (c) is again employed in next batch of recovery of metals from spent lithium titanium oxide battery;
said plurality of metals recovered in step (f) includes cobalt (Co) and electrolytic manganese dioxide (EMD);
said method recovers 97-98% of cobalt metal with % purity from 99.8-99.9%; and
said method recovers 97-98% of EMD through the electrolysis with % purity ranging from 98.5-99%.
2. The method as claimed in claim 1, wherein said roasting in step (a) is performed at a temperature range of 300-500°C for said duration of 2-4 hours and sonication in step (b) is achieved with a power capacity of 200-300 watt and operational frequency ranging from 25-35 kHz for 3-5 minutes.
3. The method as claimed in claim 1, wherein said electrolysis in step (f) is done by passing a current of 6 ampere at a temperature of 90-100°C and a current density of 200 A/m2.
4. The method as claimed in claim 1, wherein said leaching solution in step (d) is a mixture of 15-20% v/v of sulphuric acid and 4-8% w/v of hydrogen peroxide.
5. The method as claimed in claim 1, wherein said pH in step (d) is in a range of 0.5-1.0.
6. The method as claimed in claim 1, wherein said precipitating agent in step (e) is a solution including 25% w/v of soda ash, calcium hydroxide, sodium hydroxides or ammonium hydroxide.
7. The method as claimed in claim 1, wherein said electrolytic cell in step (f) includes two lead sheets as anode and one sheet of stainless steel as cathode.
8. The method as claimed in claim 1, wherein said electrolysis in step (f) is performed for 6-20 hours.
9. The method as claimed in claim 1, wherein said spent electrolyte obtained in step (g) is a solution free of cobalt and manganese that contains lithium metal in a range of 2.97-3.1 g/L.