DESC:FORM 2

THE PATENTS ACT, 1970

(39 of 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION

[See Section 10 and Rule 13]

TITLE:

“METHOD FOR REMOVAL OF ALUMINIUM FROM LEACH LIQUOR OF SPENT LITHIUM-ION BATTERIES”

APPLICANT:

ATTERO RECYCLING PVT. LTD.
A company incorporated under the 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 removal of aluminium from spent lithium-ion batteries. More particularly, the present invention relates to a method for removal of aluminium from leach liquor of spent lithium-ion batteries. The present invention provides an environmentally friendly and commercially feasible process for recovery of aluminium as aluminium phosphate from the spent lithium-ion batteries.

BACKGROUND OF THE INVENTION
A lithium-ion battery is an advanced battery technology that uses lithium ions as a key component of its electrochemistry. During a discharge cycle, lithium atoms in the anode are ionized and separated from their electrons. The lithium ions move from the anode and pass through the electrolyte until they reach the cathode, where they recombine with their electrons and electrically neutralize. The lithium ions are small enough to be able to move through a micro-permeable separator between the anode and cathode. Lithium-ion batteries are capable of having a very high voltage and charge storage per unit mass and unit volume because of lithium’s small size. Lithium-ion batteries have displaced Ni-Cd batteries as the market leader. The vast majority of commercial Lithium-ion batteries are used in consumer electronics and electric vehicles. Such devices include portable devices (such as mobile phones, laptops), power tools (such as cordless drills, saws) and electric vehicles. Hence, the use of lithium-ion batteries is witnessing tremendous market growth. Consequently, along with an increase in the use of lithium-ion batteries, a system for recycling and regenerating waste lithium ion batteries should be developed to solve the problems of contamination and risks associated with the use of lithium ion batteries. Accumulation of battery waste presents technical challenges and health hazards. Since, the environmental impact of electric cars is heavily affected by the production of lithium-ion batteries, the development of efficient ways to repurpose waste is crucial from the viewpoints of environmental preservation and recovery of valuable resources, the recycling of spent lithium ion batteries is highly desirable. The method of recovering aluminium from spent lithium-ion batteries has been taken into account by many prior arts.
IN202117027011 A discloses battery recovery process useful for the recovery of value metals from spent Li-ion batteries as high purity sulphates. This is achieved by way of an acidic leach, followed by sequential metal recovery steps using solvent extraction techniques.
JP6587861 B2 discloses about a method of processing a lithium-ion battery encapsulated by a casing containing aluminium and proposes a technique that can contribute to an improvement in the recovery rate of valuable metals contained in the lithium-ion battery. The method provides the teachings for separation of aluminium foil by roasting at low temperature.
US20220136079 A1 discloses a method of obtaining metal ions from a battery, the method involves adding a crushed battery to a leaching solution comprising fruit and organic acid, thereby obtaining a leachate comprising metal ions, wherein the method is performed at a temperature above 80°C.
Ferreira D A et al, https://doi.org/10.1016/j.jpowsour.2008.10.077, in 2009 evaluated a hydrometallurgical route based on leaching-crystallization steps for the separation of metals Al, Co, Cu and Li from spent Li-ion batteries.
Saneie et al, https://link.springer.com/article/10.1007/s40831-022-00493-0, in 2022 presented an approach for separating copper, aluminium, and plastic content from spent LIBs by froth flotation.
But, the cited prior arts disclosed above are the general process for recycling spent lithium-ion batteries and not specific over the process for the removal of aluminium in the form of aluminium phosphate from spent lithium-ion batteries.
Therefore, there is a need for an approach to provide a process which is clean, green, environmentally friendly, and commercially feasible. The method disclosed in the present invention is specific for aluminium removal. The aluminium precipitates as aluminium phosphate at low pH which minimizes the cobalt loss in the process. The method is attractive as it reduces the loss of major target metals in lithium –ion batteries such as Co, Ni, and Mn along with Li and thus, increases the efficiency of the process.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a method for removal of aluminium from spent lithium-ion batteries.
Another object of the present invention is to provide a method for removal of aluminium as aluminium phosphate from leach liquor of spent lithium-ion batteries.
Yet another object of the present invention is to provide a method for removal of aluminium by tri-sodium phosphate.
Yet another object of the present invention is to provide a method which is commercially feasible.
Still another object of the present invention is to provide a method which is simple, clean, green and environment friendly.

SUMMARY OF THE INVENTION
The present invention relates to a method of removal of aluminium from leach liquor of spent lithium-ion batteries. The present invention provides an environmentally friendly and commercially feasible process for recovery of aluminium as aluminium phosphate from the spent lithium ion batteries.
In an embodiment, the present invention provides a method for removal of aluminium from leach liquor of spent lithium ion batteries, comprising the steps of: (a) wet shredding of spent lithium ion batteries followed by floatation to obtain a shredded material; (b) sieving the shredded material obtained in step (a) followed by filtration to obtain a dry cake (black mass) and a mixture of aluminium, copper and steel; (c) removing steel from the mixture obtained in step (b) by magnetic separation; (d) separating the remaining mixture to separate aluminium and copper by density separation; (e) leaching the dry cake (black mass) obtained in step (b) at a pre-determined pH to obtain a slurry; (f) filtering the slurry obtained in step (e) to obtain a leach liquor-I (filtrate) and a dried residue; (g) removing copper from the leach liquor-I (filtrate) obtained in step (f) by electrolysis by using SS316 cathode and lead as an anode to obtain a copper free leach liquor-II; (h) removing aluminum as aluminium phosphate from the copper -free leach liquor-II obtained in step (g); (i) filtering the slurry to obtain an aluminium phosphate cake; and (j) washing the aluminium phosphate cake obtained in step (i) with distilled water and drying the cake to obtain an aluminium phosphate dried cake and an aluminium-free leach liquor-III; wherein, said leaching of step (e) is done with water and sulphuric acid by maintaining pH in a range of 0.8-1.2; said aluminium is removed as aluminium phosphate from the copper-free leach liquor-II obtained in step (g) at pH in a range of 2.5-3.5 by agitating with trisodium phosphate (50% Na3PO4) solution for 1 hour at a temperature in a range of 50-80°C.
The present invention relates to the method for removing aluminium from spent lithium ion battery in the form of aluminium phosphate at low pH. As the precipitation pH is of low range, therefore, loss of cobalt is low, the Aluminum phosphate cake act as a scavenger and takes away the other impurity iron, which is in ppm level in the leach liquor, and further the excess free phosphate is useful in reducing consumption of tri-sodium phosphate to precipitate lithium as lithium phosphate.
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 of removal of aluminium from leach liquor of the spent lithium-ion batteries of the present invention may be obtained by reference to the following drawing:
Figure 1 is a process flow for the removal of aluminium from the leach liquor of spent lithium-ion battery according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
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 should not 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 a method of removal of aluminium from leach liquor of spent lithium-ion batteries. The present invention provides an environmentally friendly and commercially feasible process for recovery of aluminium as aluminium phosphate from the spent lithium ion batteries.
In a preferred embodiment, the present invention provides a method for removal of aluminium from leach liquor of spent lithium ion batteries, comprising the steps of: (a) wet shredding of spent lithium ion batteries followed by floatation to obtain a shredded material; (b) sieving the shredded material obtained in step (a) followed by filtration to obtain a dry cake (black mass) and a mixture of aluminium, copper and steel; (c) removing steel from the mixture obtained in step (b) by magnetic separation; (d) separating the remaining mixture to separate aluminium and copper by density separation; (e) leaching the dry cake (black mass) obtained in step (b) at a pre-determined pH to obtain a slurry; (f) filtering the slurry obtained in step (e) to obtain a leach liquor-I (filtrate) and a dried residue; (g) removing copper from the leach liquor-I (filtrate) obtained in step (f) by electrolysis by using SS316 cathode and lead as an anode to obtain a copper free leach liquor-II; (h) removing aluminum as aluminium phosphate from the copper -free leach liquor-II obtained in step (g); (i) filtering the slurry to obtain an aluminium phosphate cake; and (j) washing the aluminium phosphate cake obtained in step (i) with distilled water and drying the cake to obtain an aluminium phosphate dried cake and an aluminium-free leach liquor-III; wherein, said leaching of step (e) is done with water and sulphuric acid by maintaining pH in a range of 0.8-1.2; said aluminium is removed as aluminium phosphate from the copper-free leach liquor-II obtained in step (g) at pH in a range of 2.5-3.5 by agitating with trisodium phosphate (50% Na3PO4) solution for 1 hour at a temperature in a range of 50-80°C.
Here, the shredded material obtained in step (a) is free of plastic and polymer materials and is sieved through a mesh with mesh no. 50 to obtain a shredded material with particle size below 300 µm. The trisodium phosphate is added in 1.1-1.6 times of stoichiometry to the leach liquor.
Additionally, said aluminium phosphate cake acts as a scavenger and said scavenger removes iron as an impurity in 0-50 ppm level in the leach liquor.
Further, the aluminium phosphate cake obtained in step (i) is 99-99.3% pure and the method is clean, green and environment friendly.
In another embodiment, the present invention provides a method for the removal of aluminium as aluminium phosphate consisting the steps of: adding tri-sodium phosphate to leach liquor, adjusting the pH followed by heating and agitation.
Figure 1 illustrates the process flow for the removal of aluminium from leach liquor of spent lithium-ion battery.
The invention will now be illustrated by the following non-limiting examples.
EXAMPLE 1
DETAILS OF THE PROCESS STEPS
BATCH 1:
In a 100 kg batch of spent lithium-ion batteries (mixed), the process was tested. Shredding of the batteries was carried out using a shredder having a twin shaft with a water-spraying and shearing type cutting facility. Wet shredding of the batteries followed by floatation lead to the removal of 17.6 kg of plastics and polymer materials. Then by sieving through a mesh less than 300µm followed by filtration, 46.5 kg of cake (dry wt.) and 33.09 kg mixture of aluminum, copper, and steel were collected. Magnetic separation of the mixture containing aluminum, copper, and steel led to the removal of 1.09 kg of steel. Density separation of the remaining 32 kg of aluminum and copper by air led to separating aluminum (18.7 kg) and copper (13 kg) selectively. From the dry cake (46.5 kg), 10 kg was taken for leaching with 40 L of water and 1.8 L of sulphuric acid in the first batch by maintaining the pH of 0.8-1.2. Table 1 presents the chemical composition of the dried powder.

Table 1
Chemical composition of dried powder
Elements Co Li Mn Ni Cu Al
% 7.17 1.74 3.74 2.73 2.25 1.11

The above slurry was filtered and both filtrate (leach liquor-1 = 45 L) and the dried residue (graphite = 2.2 kg) were collected. The analysis of the leach liquor-1 is presented in Table 2.
Table 2
Chemical analysis of leach liquor-1
Elements Co Li Mn Ni Cu Al
g/L 15.9 3.8 8.3 6 5 2.45

From the above leach liquor, copper was removed as copper powder by well-known electrolysis using SS316 cathode and lead (Pb) anode and the weight of copper powder collected was 222 g.
From the copper-free leach liquor-2, aluminum (Al) was removed as aluminum phosphate (0. 647kg) at a pH of 3.4 by agitation with 50% trisodium phosphate (Na3PO4) of solution (3.5 L-1.76kg) for 1 h at 50-80oC. The slurry was filtered and the cake was washed with distilled water and dried. The analysis of 50 L of the aluminum-free liquor (leach liquor-3) is presented in Table 3. The analysis of dried cake (Aluminum phosphate-99% pure) was presented in Table 4.

Table 3
Chemical analysis of leach liquor-3
Elements Co Li Mn Ni Cu Al
g/L 14.31 3.42 7.47 5.4 0.03 0.02

Table 4
Chemical analysis of aluminum phosphate
Elements Co Li Mn Ni Cu Al
% 0.2 0.01 0.05 0.001 0.0001 17

BATCH 2:
In a 100 kg batch of spent lithium-ion batteries (mixed), the process was tested. Shredding of the batteries was carried out using a shredder having a twin shaft with a water spraying and shearing type cutting facility. Wet shredding of the batteries followed by floatation lead to the removal of 17.7 kg of plastics and polymer materials. Then by sieving through a mesh less than 300µm followed by filtration, 46.6 kg of cake (dry wt.) and 33.09 kg mixture of aluminum, copper, and steel were collected. Magnetic separation of the mixture containing aluminum, copper, and steel led to the removal of 1.1 kg of steel. Density separation of the remaining 32 kg of aluminum and copper by air led to separating aluminum (18.8 kg) and copper (13.1 kg) selectively. From the dry cake (46.6 kg), 10 kg was taken for leaching with 40 L of water and 1.8 L of sulphuric acid in the first batch by maintaining the pH of 0.8-1.2. Table 5 presents the chemical composition of the dried powder.

Table 5
Chemical composition of dried powder
Elements Co Li Mn Ni Cu Al
% 7.16 1.73 3.72 2.72 2.23 1.1

The above slurry was filtered and both filtrate (leach liquor-1 = 46 L) and the dried residue (graphite = 2.3 kg) were collected. The analysis of the leach liquor-1 is presented in Table 6.
Table 6
Chemical analysis of leach liquor-1
Elements Co Li Mn Ni Cu Al
g/L 15.8 3.78 8.2 5.9 5.1 2.45

From the above leach liquor, copper was removed as copper powder by well-known electrolysis using SS316 cathode and lead (Pb) anode and the weight of copper powder collected was 227g.
From the copper-free leach liquor-2, aluminum (Al) was removed as aluminum phosphate (0. 646kg) at a pH of 3.5 by agitation with 50% Na3PO4 of solution (3.55 L-1.77 kg) for 1 h at 50-80oC. The slurry was filtered and the cake was washed with distilled water and dried. The analysis of 50 L of the aluminum-free liquor (leach liquor-3) is presented in Table 7. The analysis of dried cake (Aluminum phosphate >99% pure) was presented in Table 8
Table 7
Chemical analysis of leach liquor-3
Elements Co Li Mn Ni Cu Al
g/L 14.32 3.41 7.42 5.3 0.02 0.022

Table 8
Chemical analysis of Aluminum phosphate
Elements Co Li Mn Ni Cu Al
% 0.19 0.01 0.05 0.001 0.0001 17

The purified leach liquor of both the batch together is taken for cobalt recovery.
Therefore, the present invention provides a simple, clean, easy to approach, environmentally friendly and commercially feasible method for the removal of aluminium from the spent lithium ion batteries in the form of aluminium phosphate. The aluminium precipitates as aluminium phosphate at low pH which minimizes the cobalt loss in the process. The method is attractive as it reduces the loss of major target metals in lithium –ion batteries such as Co, Ni, and Mn along with Li and thus, increases the efficiency of the process.
Many modifications and other embodiments of the invention set forth herein will readily occur to one skilled in the art to which the invention pertains 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 removal of aluminium from leach liquor of spent lithium ion batteries, comprising the steps of:
a) wet shredding of spent lithium ion batteries followed by floatation to obtain a shredded material;
b) sieving the shredded material obtained in step (a) followed by filtration to obtain a dry cake (black mass) and a mixture of aluminium, copper and steel;
c) removing steel from the mixture obtained in step (b) by magnetic separation;
d) separating the remaining mixture to separate aluminium and copper by density separation;
e) leaching the dry cake (black mass) obtained in step (b) at a pre-determined pH to obtain a slurry;
f) filtering the slurry obtained in step (e) to obtain a leach liquor-I (filtrate) and a dried residue;
g) removing copper from the leach liquor-I (filtrate) obtained in step (f) by electrolysis by using SS316 cathode and lead as an anode to obtain a copper free leach liquor-II;
h) removing aluminum as aluminium phosphate from the copper -free leach liquor-II obtained in step (g);
i) filtering the slurry to obtain an aluminium phosphate cake; and
j) washing the aluminium phosphate cake obtained in step (i) with distilled water and drying the cake to obtain an aluminium phosphate dried cake and an aluminium-free leach liquor-III;
wherein,
said leaching of step (e) is done with water and sulphuric acid by maintaining pH in a range of 0.8-1.2;
said aluminium is removed as aluminium phosphate from the copper-free leach liquor-II obtained in step (g) at pH in a range of 2.5-3.5 by agitating with trisodium phosphate (50% Na3PO4) solution for 1 hour at a temperature in a range of 50-80°C.

2. The method as claimed in claim 1, wherein the shredded material obtained in step (a) is free of plastic and polymer materials.

3. The method as claimed in claim 1, wherein the shredded material obtained in step (a) is sieved through a mesh to obtain a shredded material with particle size below 300 µm.

4. The method as claimed in claim 1, wherein the trisodium phosphate is added in 1.1-1.6 times of stoichiometry to the leach liquor.

5. The method as claimed in claim 1, wherein said aluminium phosphate cake acts as a scavenger and said scavenger removes iron as an impurity in 0-50 ppm level in the leach liquor.

6. The method as claimed in claim 1, wherein the aluminium phosphate cake obtained in step (i) is 99-99.3% pure.

7. The method as claimed in claim 1, wherein said method is clean, green, environmental friendly and commercially feasible.