TWI726033B - Process for recovering metal values from spent lithium ion batteries with high manganese content - Google Patents

Abstract

The present invention relates to an improved process and method of recovering metals of value from used Lithium batteries (hereinafter LiBs). More particularly, the invention provides a method for recovering cobalt, lithium, manganese along with other metals of value from used LiBs rich in manganese content. The method includes combination of chemical and physical processes for separation, limiting the use of chemical for removing minor impurities. The invention provides for a cost effective, economic and environmental friendly process for recovering metals of value. The method comprises the following major steps of wet shredding, filtration followed by electrolysis in preferred conditions, density and magnetic separation procedures. The purity of metals obtained by using the proposed process is more than 99%.

Description

Method for recovering valuable metals from waste lithium ion batteries with high manganese content

The present invention relates to an improved treatment and method for recovering valuable metals from used lithium batteries (hereinafter referred to as LiB). In particular, the present invention provides a method for recovering cobalt, lithium, manganese and other valuable metals from used LiB rich in manganese content. The method involves a combination of chemical treatment and physical treatment to separate and limit the chemicals used to remove small amounts of impurities. The present invention provides a cost-effective, economical and environmentally friendly method for recovering valuable metals.

Lithium-ion batteries are commonly referred to as Li-ion batteries or LiB, and are a member of a family of rechargeable batteries in which lithium ions move from the negative electrode to the positive electrode during discharge and return during charging. Compared with metallic lithium used in non-rechargeable lithium batteries, Li-ion batteries use intercalated lithium compounds as an electrode material. The electrolyte that allows the movement of ions and the two electrodes are the components of a lithium-ion battery.

Lithium-ion batteries are commonly seen in consumer electronics. They are the most popular type of rechargeable batteries used in portable electronic products, with It has high energy density, no memory effect and only slowly loses power when not in use. In addition to consumer electronics, LiB is also increasingly popular in military, battery-electric vehicles, and aerospace applications. For example, lithium-ion batteries are becoming a common alternative to lead-acid batteries traditionally used in golf and utility vehicles. Instead of heavy lead plates and acid electrolyte, the trend is to use lightweight lithium-ion battery components that can provide the same voltage as lead-acid batteries, so there is no need to modify the vehicle's drive system. Due to the advantages of lithium-ion batteries, such as high power density, high working voltage, long cycle life, and no memory effect, lithium-ion batteries have been recognized as a battery system with high development potential. Therefore, the use of lithium-ion batteries is witnessing huge market growth. Therefore, as the use of lithium ion batteries increases, a system for recycling and regenerating waste lithium ion batteries should be developed to solve the pollution and risk problems associated with the use of lithium ion batteries.

Currently, there are two main types of recycling processes used for lithium-ion batteries.

1) These batteries together with separators and fluxes are fed into an electronic incinerator that already contains molten steel and anode-reduced carbon to be enriched in cobalt, nickel and/or manganese to form a stainless steel alloy. Lithium is melted into the slag and can be recovered with several additional processing steps at a high cost. This is called Umicore processing.

2) The battery is processed by a hammer mill and the -25 mesh slurry is filtered and packaged. This slurry contains about 30% metal and carbon from the cathode. This metal-rich mixture is transported to an electric smelter to make steel. Copper and aluminum foil are recovered separately from this process.

Although valuable cobalt and nickel are recycled together with manganese at the price of scrap metal, it is detrimental The full value of the lithium metal oxide cathode material is lost and the lithium metal oxide is usually not recovered. If the full value of lithium metal oxide cathode materials is realized through complete recycling and regeneration to be directly reused in new lithium-ion batteries, this will be the main improvement for recycling strategic materials. In addition, almost all lithium will also be recovered in the cathode material and used as part of the lithium metal oxide cathode because it is regenerated and used in new batteries.

The recovery and reuse of cathode materials can reduce the pressure of supplying lithium cathode materials such as cobalt and nickel.

US Patent No. 8616475 discloses a processing method for recovering copper, aluminum, carbon and cathode materials from waste lithium-ion batteries with lithium metal oxide cathode materials. The main disadvantages of the disclosed method are its limited recycling properties and the low efficiency of recycling metals in their purest form. This method ignores other recyclable materials of lithium-ion batteries, including those present in the protective circuit board. Therefore, a single universal solution is needed to recover all valuable materials that exist in waste lithium-ion batteries in the purest form of metal.

Chinese Patent No. 101988156 discloses a method for recovering metal components from waste lithium-ion batteries, in which the metal components are recovered in a pH-controlled environment. In addition, the method includes the use of an organic solution to maintain the pH of the processing environment. pH-sensitive solutions require special attention and work effectively at a specific pH, which leads to incomplete metal recovery, especially when the pH deviates from a specific range. This solution is considered to be less efficient because of incomplete processing, which also affects the quality and quantity of recovered metal.

Chinese Patent No. 1601805A discloses a method for recovering and disposing of worn-out lithium ion batteries to recover cobalt, copper and precious metal elements. Generic elements such as lithium. In this method, the battery components are first crushed, and then the metal is recovered using a chemical scheme according to the metal to be recovered. This method produces hydrogen fluoride, which can be immediately converted to hydrofluoric acid, which is highly corrosive and toxic and has serious health effects under exposure. In addition, the recovered metal has a concern of low purity.

US Publication No. 20130302226A1 discloses a method and equipment for extracting useful elements such as cobalt, nickel, manganese, lithium and iron from waste lithium-ion batteries to produce active cathode materials for new batteries. The disclosed method lacks versatility to recover the metal content of waste lithium-ion batteries. In addition, the disclosed method concerns mixed cathode chemistries and does not pay much attention to the purity of the cathode extracts in their purest form.

In addition, most of the known treatment methods in the prior art use harmful chemicals to recover metals in large amounts. On the other hand, the prior art physical treatment methods cannot lead to satisfactory metal recovery in terms of quantity and quality. Therefore, there is a need for an eco-friendly and cost-effective method to recover valuable metals in large quantities without sacrificing quality. The recovery and reuse of cathode materials can reduce the pressure of supplying lithium cathode materials such as nickel and cobalt.

Most of the processes known in the prior art use hazardous chemicals to recover metals in large quantities. On the other hand, the physical treatment of the prior art cannot lead to satisfactory metal recovery in terms of quantity and quality.

Therefore, there is a need for an eco-friendly and cost-effective method to recover valuable metals in large quantities without sacrificing quality.

Therefore, the main objective of the present invention is to provide an improved treatment and method for recovering valuable metals such as nickel, cobalt, manganese, copper, iron and aluminum from used LiB.

Another object of the present invention is to provide a method for recovering valuable metals in a highly purified form of the metals.

Another object of the present invention is to provide a method that utilizes the smallest amount of chemical reactants in the overall recovery process.

Another object of the present invention is to provide a method for recovering valuable metals in a highly purified form of metals in an in-situ resource utilization scheme.

Another object of the present invention is to provide a method for recovering valuable metals from a lithium ion battery, which mainly includes a physical treatment method for separation, and limits the use of chemicals for removing a small amount of impurities.

Another object of the present invention is to provide a cost-effective, economical and environmentally friendly method for recovering valuable metals.

Another object of the present invention is to provide an eco-friendly and cost-effective method to recover valuable metals in large quantities without sacrificing quality.

The present invention relates to a method for recovering valuable metals from used lithium batteries with high manganese content. Valuable metals include nickel, cobalt, manganese, copper, iron, aluminum and so on. In this method, lithium ion batteries are used as raw materials, which undergo unit operations such as crushing, sieving, washing, filtering, precipitation, leaching, electrolytic separation, density separation, and magnetic separation to recover nickel, cobalt, manganese, copper, Valuable metals such as iron and aluminum. The benefits provided by the method of the present invention include low processing costs, high recovery rates of copper and nickel-cobalt-manganese, resulting in greater social and economic benefits beneficial.

In an embodiment of the present invention, the method for recovering valuable metals from a used lithium battery includes the following main steps.

i) Wet crush the battery.

ii) Flotation followed by wet sieving.

iii) Filter the mixed metal powder separated from the lithium ion.

iv) Electrolytic treatment of dissolved cobalt.

v) Remove aluminum from leach liquor.

vi) Electrolytic treatment for recovery of pure cobalt metal and manganese dioxide.

vii) Used to remove the magnetic separation of PCB, copper and aluminum substrates.

viii) The washing solution in the precipitation step (iii) is recovered as lithium as lithium carbonate.

In the embodiment of the present invention, the maximum amount of elements is separated by physical methods rather than chemical methods, which is beneficial to save costs in the chemical treatment methods of liquid and solid effluents. Only chemicals are used to dissolve small amounts of impurities from the electrolyte, which makes this treatment method economically attractive. Therefore, this treatment method is different from those commonly used in which chemicals are used to dissolve the main elements and then used to separate the main elements from other impurities. This makes the method of recovering valuable metals environmentally friendly.

The system and method of the present invention can be fully understood by referring to the following drawings.

Fig. 1 is a flowchart illustrating a process according to an embodiment of the present invention.

The invention will now be described below with reference to the accompanying drawings, in which some but not all embodiments of the invention are shown. Although the present invention can be implemented in many different forms, it should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be careful and will fully convey the scope of the present invention to those having ordinary knowledge in the art.

Figure 1 illustrates the process and method for recovering valuable metals from used lithium-ion batteries, which essentially do not use chemical solutions. The treatment method mainly depends on the physical separation of the metal and does not sacrifice the quality of the recovered products and by-products. The method of the present invention includes the following steps:

i) Wet crush the battery.

ii) Flotation followed by wet screening.

iii) Filter the mixed metal powder separated from the lithium ion.

iv) Electrolytic treatment of dissolved cobalt.

v) Remove aluminum from the leachate.

vi) Electrolytic treatment for recovery of pure cobalt metal and manganese dioxide.

vii) Used to remove the magnetic separation of PCB, copper and aluminum substrates.

viii) The washing solution in the precipitation step (iii) is recovered as lithium as lithium carbonate.

Lithium batteries are crushed and sieved in a wet environment. The content considered to be too large is further sent to the density separation step, which depends on the density of the plastic and metal content causing their separation. On the other hand, particles that are too small are washed and filtered separately. The obtained filtrate and residue are treated separately for recovery Collect valuable metals. The lithium, copper, aluminum, and PCB obtained by precipitation from the washing liquid using a saturated sodium carbonate solution are separated by magnetic separation followed by density separation.

The residue obtained after filtration is then sent to electrolytic treatment for cobalt leaching and separation of cobalt and manganese. In the final step of electrolysis, manganese dioxide and cobalt are obtained in pure form.

The main steps of the processing method are described in detail below.

i) Wet pulverized battery: In this step, the waste battery is fed into a pulverizer with a water level higher than the battery level so that the water will act as a detergent and also a temperature control agent. The crusher is designed in such a way that the size of the crushed (battery) is less than 10mm.

ii) Flotation followed by wet screening: In this step, the slurry is output from the pulverizer, the plastic/Teflon matrix floating on the water level is removed and then the slurry particles with a size of less than 600 microns are passed through a sieve. From the above screening, metals such as copper foil, aluminum shell and PCB are collected.

iii) Filtering the mixed metal powder separated from lithium ions: In this step, the slurry containing particles with a size of less than 600 microns is filtered through a pressure filter. The filtrate contains dissolved lithium ions. The filter cake contains cobalt ions with some metallic impurities and an organic matrix.

iv) Electrolysis treatment for dissolved cobalt: the filter cake obtained from step (iii) is put into the anode compartment of the electrolysis chamber. The electrolysis chamber consists of a cathode made of SS-316 and a lead anode separated by a filter cloth. In the first cycle, the electrolyte is a mixture of 10% sulfuric acid. After the second cycle, the spent electrolyte (ie, leachate) is further processed to remove aluminum. The final pH of the electrolyte Is maintained at 1.2. The deposited copper powder is stripped from the cathode.

v) Remove aluminum from the leachate: increase the pH to 5.5 by using sodium hydroxide and purify the above-mentioned leachate by removing traces of aluminum.

vi) Electrolytic treatment for recovering pure cobalt metal and manganese dioxide: the purified leachate of step (v) is fed into the cathode compartment of another chamber. The anolyte of this chamber is pumped out and fed into chamber 1 (the acid produced by depositing cobalt on the anode and manganese dioxide on the cathode is used to leaching the metal content of the mixed metal powder of the battery). The temperature of the chamber is maintained above 95°C to deposit manganese as manganese dioxide.

vii) The washing liquid of the precipitation step (iii) is used as lithium recovery of lithium carbonate: In this step, the washing liquid obtained from step (iii) is treated with a saturated solution of soda ash to increase the pH value and reduce the pH to 90 ℃ to 100 ℃ maintain the pH value between 11-11.5 for 4 hours.

viii) Removing and separating the PCB, copper and aluminum substrate of step (ii): In this step, the floating substrate of the mixture of PCB, copper and aluminum obtained from step (iii) is collected. Using density separation in water, plastic materials float and are removed, and higher density particles including PCB particles, copper, iron, and aluminum are separated by using a magnetic separator. The magnetic part contains iron-containing particles and PCB gold-containing particles. The non-magnetic part is rich in copper and aluminum. The non-magnetic particles have once again undergone the density separation method used to separate copper and aluminum.

In a preferred embodiment, the present invention provides a processing method for recovering metals from waste lithium batteries including the following steps.

a) The lithium battery is crushed into the preferred size of particles in the water, so that the water level is higher than the level of the battery to obtain crushed particles and Slurry for floating plastic and Teflon matrix.

b) Remove the floating plastic and Teflon matrix of step a).

c) Wet sieving the slurry obtained in step a) through a sieve of at least 30 mesh size to separate particles of different sizes; the coarser pieces containing copper, aluminum and protective circuit modules are retained and collected by the sieve , And the finer particles containing lithium, manganese and cobalt are aggregated in the slurry.

d) Filtering the aggregates containing lithium, manganese and cobalt in step c) through a pressure filter to obtain a washing solution containing lithium and residues containing cobalt, manganese, metal impurities and organic matrix.

e) Electrolyze the residue of step d) using concentrated sulfuric acid as the electrolyte at the preferred pH to obtain copper and leachate at the anode.

f) Treat the leachate obtained in step e) with a sodium hydroxide solution to obtain a treated slurry.

g) Filter the treated slurry of step f) to obtain a metal compound filter cake and a filtrate.

h) Electrolyze the filtrate of step g) to obtain metal at the anode, metal oxide at the cathode, and acid.

i) Treat the washing solution of step d) with a saturated solution of soda ash at a pH range of 11 to 11.5 and a temperature range of 80°C to 120°C for 3 to 6 hours to obtain a lithium carbonate precipitate and an overlying liquid.

j) Use a magnetic separation process to separate magnetic particles and non-magnetic particles from the coarser pieces obtained in step c).

In the embodiment, the processing method of the present invention provides several advantages over the techniques available in the prior art, that is, the processing method of the present invention does not use high temperature. Exposure, the organic matrix is decomposed by electrolytic oxidation at the anode, and the nascent oxygen generated at the anode is used as an oxidant to dissolve the cobalt content in the sulfuric acid medium. In this way, the initial oxygen generated in the environment is utilized as an oxidant and therefore an in-situ resource utilization scheme is set up in the metal recovery process. In addition, the use of sulfuric acid as the electrolyte system is used for batch processing of initial circulation. In subsequent cycles, the electrolyte from the previous batch can be reused.

The purity of the product obtained during this treatment was analyzed by Microwave Plasma Atomic Emission Spectrometer (MP-AES). The purity of the obtained cobalt metal was about 99% and the purity of lithium carbonate was 98%.

The invention will now be illustrated by the following non-limiting examples.

Example 1

The treatment is to test 100Kg batches of (mixed) waste lithium-ion batteries. Initially, the battery was crushed using a shredder, which had dual-shaft and water-jet and shear-type cutting equipment. Flotation after wet crushing of the battery resulted in the removal of 16.4 Kg of plastic and polymer materials. After that, the content is screened through a sieve (less than 600 μm) and then filtered. Collect about 47.2 Kg of filter cake (dry weight) and 33.9 Kg of a mixture of aluminum, copper, and steel containing PCB.

The mixture containing aluminum, copper, and steel containing PCB undergoes a magnetic separation step, which results in the removal of 1.09 Kg of PCB for gold recovery processing. The remaining mixture (about 32Kg of aluminum and copper) is separated through a density separation step, in which aluminum (18.7Kg) and copper (13Kg) are selectively separated. By maintaining a pH of 1-1.2, electrochemical leaching is a continuous process to process the dry cake (47.2Kg). Table 1 shows the chemical composition of the dry powder.

Example 2

Electrochemical leaching of the dry cake was carried out in a rectangular chamber (54L capacity) containing anodes (5 pcs, made of lead, 240x100mm) and cathodes (4 pcs, made of SS-316, 330x100mm). The 5 anodes are covered with polypropylene bags, each bag contains 2Kg of dry filter cake, and the 4 cathodes are placed in staggered positions with the help of copper hanging posts, and the inside of the chamber is kept containing 35L water and 7.75 L of concentrated sulfuric acid. For the electrolysis chamber, a current of 50 amperes was passed for 3 hours to leached the material. During leaching, copper powder (0.5 Kg) was stripped from the cathode in the first cycle. The composition of the leachate is shown in Table 2 below.

Example 3

The leachate was used with a pH 5.5 sodium hydroxide solution (40% w/v, 3L) and stirred for 1 hour to remove aluminum. The aluminum hydroxide filter cake (1.2Kg) was removed by filtering the slurry with washing and drying. The above-mentioned filtrate (42Lt) is placed in another electrolysis chamber (containing 5 lead anodes and 4 SS-316 cathodes) to recover copper and manganese. After passing a current of 100 amperes at 90°C to 100°C for 4 hours, 0.336Kg of copper and 0.168Kg of manganese dioxide were stripped from the cathode and the anode, respectively. The acid produced by the manganese dioxide deposited at the anode and the cobalt deposited at the cathode is fed into the leaching chamber. Group of feed and waste electrolyte The results are presented in Table 3 below.

Example 4

Starting from the second cycle, waste electrolyte leaching is used instead of water and sulfuric acid. Follow the same procedure to remove aluminum and use the aluminum-free solution recovered by the above-mentioned electrolysis method of cobalt and manganese dioxide. By maintaining the concentration of cobalt and manganese in the electrolyte after 4 cycles, the total recovered cobalt metal and manganese dioxide are 1.34Kg and 0.67Kg, respectively. The purity of the recovered cobalt metal and manganese dioxide are 99.3% and 96.5%, respectively. The chemical analysis of the recovered cobalt metal and manganese dioxide (MnO ₂ ; EMD) is shown in Table 4 below.

BDL=below detection level

Claims (10)

A method for metal recovery, used to recover metal from waste lithium batteries, includes the following steps: a) crushing lithium batteries in water to particles of a preferred size so that the water level is higher than the level of the battery to obtain crushed particles, floating plastics, and iron Flon matrix slurry; b) remove the floating plastic and the Teflon matrix of step a); c) wet screen the slurry obtained in step a) through a sieve of at least 30 mesh size to separate different sizes of Particles; the coarser pieces containing copper, aluminum and protective circuit modules are retained and collected by the sieve, and the finer particles containing lithium, manganese and cobalt in the slurry are aggregated; d) Pass through a pressure filter Filtering the lithium, manganese and cobalt aggregates of step c) to obtain a washing solution containing lithium and residues containing cobalt, manganese, metal impurities and organic matrix; e) using concentrated sulfuric acid as an electrolyte at a preferred pH for the electrolysis step The residue of d) is to obtain copper at the anode and the leachate; f) the leachate obtained in step e) is treated with a sodium hydroxide solution to obtain a treated slurry; g) the treated slurry of step f) is filtered H) electrolyzing the filtrate of step g) to obtain metal at the anode, metal oxide and acid at the cathode; i) Treat the washing solution of step d) with a saturated solution of soda ash at a pH range of 11-11.5 and a temperature range from 80°C to 120°C for 3 to 6 hours to obtain a lithium carbonate precipitate and an upper liquid; and j) Use a magnetic separation process to separate magnetic particles and non-magnetic particles from the coarser pieces obtained in step c). The method for recovering metals as described in claim 1, wherein the preferred size of the particles obtained after pulverization is 10 mm. The method for recovering metals as described in claim 1, wherein the preferred pH of the concentrated sulfuric acid used for electrolysis is maintained in the range of pH 1-1.2. The method for recovering metals as described in claim 1, wherein the obtained metal compound filter cake is washed and dried to obtain aluminum hydroxide. The method for recovering metals as described in claim 1, wherein the leachate is treated with a 40% w/v sodium hydroxide solution at pH 5.5 and agitation for 1 hour. The method for recovering metal as described in claim 1, wherein the metal obtained at the anode is cobalt with a purity higher than 99%. The method for recovering metals as described in claim 1, wherein the metal oxide obtained at the cathode is manganese oxide having a metal content higher than 60%. The method for recovering metal as described in claim 1, wherein the thicker piece of step c) is treated with a magnetic separator to separate the magnetic particles including the protective circuit module including steel from the non-magnetic particles including copper and aluminum, The non-magnetic particles further use a density separation process to separate aluminum and copper. The method for recovering metals as described in claim 1, wherein the acid obtained in step h) forms a preferred electrolyte in the subsequent electrolysis cycle in the subsequent batch processing. The method for recovering metals as described in claim 1, wherein the lithium carbonate has a purity of 98%, wherein the lithium content is greater than 18% and the impurity level is less than 0.5%.

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