CN1287481C - Method for recovering valuable metals from waste secondary batteries - Google Patents

Abstract

The invention relates to a new technology for recovering metal and valuable resources from waste lithium ion/nickel-hydrogen/nickel-cadmium batteries. The method of the invention is to roast the used waste lithium ion/nickel-hydrogen/nickel-cadmium battery in a high temperature furnace and sieve the battery to produce fine powder containing metal and metal oxide. The fine powder is dissolved and filtered in two stages, cadmium sulfate is crystallized and separated out from the filtrate obtained by the first stage dissolution and filtration, and iron, aluminum and rare earth metals are precipitated and recovered by hydroxide by adjusting the pH value of the filtrate obtained by the second stage dissolution and filtration. The remaining filtrate is subjected to extraction and back extraction procedures to obtain two aqueous solutions containing cobalt and nickel, which are then electrolyzed to separate out high-purity cobalt and nickel metals. The residual aqueous solution after nickel metal electrolysis is added with a water-soluble carbonate to precipitate lithium ions in the aqueous solution as carbonate.

Description

Method for recovering valuable metals from waste secondary batteries

Technical field

The invention relates to a method for recovering valuable metals from waste lithium-ion/nickel-hydrogen/nickel-cadmium batteries.

Background technique

Due to its high energy density, high working voltage, long cycle life and no memory effect, lithium-ion batteries have been recognized as the battery system with the most development potential. At present, in addition to being widely used in various The 3C products are on the market, and are expected to replace nickel-cadmium and nickel-metal hydride secondary batteries as the power source of electric vehicles in the future. Even so, NiCd and NiMH batteries are still widely used in some specific applications. Therefore, a large number of nickel-cadmium and nickel-metal hydride batteries can still be found mixed in the waste lithium-ion batteries in the actual recovered waste secondary batteries. Therefore, there is a need to develop an efficient recovery method for valuable metals from mixed spent secondary batteries.

The applicant of this case discloses a method for recovering valuable metals from waste lithium-ion batteries in the invention patent application number CN01130735.8 (parallel U.S. Patent No. 6514311), including roasting the used waste lithium-ion batteries in a high-temperature furnace , decompose and remove the organic electrolyte, sieve after crushing, and then use magnetic separation and eddy current sorting to separate the broken iron shell, copper foil and aluminum foil, etc. With the control of pH value and electrolysis conditions, metal copper and cobalt are electrolyzed by diaphragm electrolysis, and the acid generated on the cathode side during the electrolysis process can be recovered through diffusion dialysis and recycled to the dissolution step, forming a closed process . And the solution rich in lithium ions after electrolysis, after adjusting the pH value to precipitate metal impurities, can add carbonate to form high-purity carbonate of lithium to recover lithium. The content of that case is incorporated by reference into this case.

Contents of Invention

The object of the present invention is to disclose a method for recovering valuable metals from waste secondary batteries including lithium-ion batteries, nickel-hydrogen batteries and nickel-cadmium batteries, wherein the waste secondary batteries produce a Ashes containing metals and metal oxides, the method comprises the following steps:

a) Dissolving the ashes with a sulfuric acid aqueous solution of 2 to 6 molar concentrations containing hydrogen peroxide;

b) adding an alkali to the corrosion solution produced in step a), so that the cadmium and rare earth metal ions therein are crystallized;

c) the mixture of solid-liquid separation step b);

d) extracting the aqueous solution obtained in step c) with the first organic extractant to produce an aqueous layer rich in nickel and cobalt ions and an organic layer rich in cadmium, iron and zinc ions;

e) extracting the aqueous layer obtained in step d) with a second organic extractant to produce an organic layer rich in cobalt ions and an aqueous layer rich in nickel ions;

f) back-extracting the organic layer rich in cobalt ions with aqueous sulfuric acid to produce an aqueous layer rich in cobalt ions;

g) using the nickel-ion-rich water layer obtained in step e) as an electrolytic solution to perform electrolysis at a voltage of 1.5-4.0 volts, so that nickel metal is reduced on a cathode;

h) using the water layer rich in cobalt ions obtained in step f) as an electrolyte to perform electrolysis at a voltage of 1.5-4.0 volts, so that cobalt metal is reduced on a cathode; and

i) adding a water-soluble carbonate to the electrolytic solution after electrolysis in step g) to form a lithium carbonate precipitate.

Preferably, steps a) and b) are combined to include:

a1) Dissolving the ashes with an aqueous sulfuric acid solution of 2 to 6 molar concentrations;

a2) the mixture of the solid-liquid separation step a1);

a3) dissolving the solid produced in step a2) with an aqueous sulfuric acid solution of 4 to 12 NM containing hydrogen peroxide;

b1) evaporating part of the water in the corrosion solution produced in step a2) to obtain a precipitate with cadmium sulfate crystals as its main part;

b2) adding a base to the corrosion solution produced in step a3) to obtain a precipitate with rare earth metal hydroxides, Fe(OH ₎ and Al(OH ₎ as the main parts,

Wherein the mixture produced in step b2) is taken as the mixture of solid-liquid separation in step c).

More preferably, the mixture produced in step b1) is separated from the solid-liquid, and the liquid obtained by the solid-liquid separation is used as a part of the aqueous solution of sulfuric acid from 4 NM to 12 NM in step a3), and the precipitate About 85% by weight is cadmium sulfate.

More preferably, the alkali in step b2) is sodium hydroxide, and the amount of sodium hydroxide is such that the pH value of the solution is about 6.

Preferably, the water-soluble carbonate in step i) of the method of the present invention is sodium carbonate.

Preferably, the method of the present invention further comprises back-extracting the organic layer rich in cadmium, iron and zinc ions in step d) with sulfuric acid aqueous solution to obtain an aqueous layer rich in cadmium, iron and zinc ions; Cadmium, iron and zinc ions in the water layer are removed.

Preferably, the method of the present invention further comprises crushing the calcined product, and collecting the crushed product with a 20-5 mesh screen during the crushing process. More preferably, the method of the present invention further comprises separating the crushed product with a sieve whose mesh size is between 10 and 5 meshes, so as to obtain an ashes containing metal and metal oxides passing through the sieve and an ash that cannot pass through the sieve. of the sieve.

Preferably, the method of the present invention further comprises separating iron from the oversize by magnetic separation. More preferably, the method of the present invention further includes separating copper and aluminum in the residue produced after the aforementioned magnetic separation by means of eddy current separation.

The present invention uses a complete physical separation unit and a chemical purification system designed with the characteristics of each metal to perform perfect treatment and recovery of all metals in lithium-ion/nickel-metal hydride/nickel-cadmium batteries, and can greatly improve the recovery of metals rate and quality of recovered metal.

Implementation

At present, commercial lithium-ion batteries, nickel-hydrogen batteries and nickel-cadmium batteries can be mainly divided into two types according to their application characteristics: cylindrical and square. Or the aluminum foil is used as the positive plate, and the metal alloy or graphite is coated on the copper foil as the negative plate. The separator is placed between the two plates, and the electrolyte is filled and then crimped and compressed to the required specifications, and then connected to the conductive handle. , Pressure relief safety valve and end cover and other parts, seal the iron or aluminum tank body and put it on the plastic shell to form. Therefore, when dealing with waste lithium-ion/nickel-metal hydride/nickel-cadmium batteries, the types of metals faced are nothing more than iron, cobalt, nickel, cadmium, aluminum, copper, lithium and rare earth metal elements, and the non-metallic parts are mainly plastics , carbon or graphite.

Looking at the currently published technologies, it can be found that each technology only studies and discusses the treatment and recycling of one secondary battery. Cadmium... There is considerable difficulty in effectively classifying it. If only one type of battery treatment process is considered, once other batteries are mixed in to cause interference from impurities, it is likely to exceed the tolerance of the original manufacturing process.

The present invention is a new technology for recovering metals and valuable resources from waste lithium-ion/nickel-metal hydride/nickel-cadmium batteries. rate increased substantially. However, the method of the present invention is still mainly to roast the used waste lithium-ion/nickel-hydrogen/nickel-cadmium battery in a high-temperature furnace, decompose and remove the organic matter, and then pulverize it, and then use the purpose of sieving to obtain pulverized bodies of different particle sizes. For coarse-grained pulverized objects, the broken iron shell can be separated and recovered by magnetic separation, and copper foil and aluminum foil can be recovered by eddy current separation. The fine powder part containing plate metal and metal oxide is subjected to two-stage dissolution and filtration treatment. Crystallize cadmium sulfate or electrolytically separate cadmium metal from the filtrate obtained from the first stage of dissolution and filtration, and adjust the pH value of the filtrate obtained from the second stage of dissolution and filtration to separately precipitate and recover iron, aluminum and rare earth metals as hydroxides . The remaining filtrate is subjected to a series of extraction and back extraction to obtain two aqueous solutions rich in cobalt and nickel respectively. They are then electrolyzed to separate cobalt and nickel metals, respectively. After the electrolysis of nickel metal, the remaining aqueous solution is added with a water-soluble carbonate to precipitate lithium ions in the form of carbonate.

Compared with the currently published technology, the present invention not only has a relatively high metal recovery rate and metal quality, but also can process the most widely used lithium-ion, nickel-metal hydride, and nickel-cadmium secondary batteries on the market with a set of systems. In addition to greatly improving the tolerance of the processing and recycling system for material sources, it can also greatly reduce equipment costs.

A preferred embodiment of the present invention will be described as follows in conjunction with the flowchart of FIG. 1 . The discarded (or defective products in the manufacturing process) lithium-ion, nickel-metal hydride, and nickel-cadmium batteries (1) are cracked and punched with a shell breaker (2), and then placed in a high-temperature furnace at 250 ° C to 350 ° C (3) The roasting temperature should not exceed 350C. Excessively high roasting temperature will cause a large amount of cadmium metal to form cadmium vapor and volatilize and escape. The organic matter (4) in the battery will decompose due to high temperature to form carbon dioxide/carbon monoxide and escape, and part of the oxide in the battery will be reduced, or coke will be deposited in the battery. The roasted waste secondary battery raw materials are sent to the crushing system (5). During the crushing process, the mesh size is preferably 5-20 mesh. Because iron, copper, and aluminum have better ductility, they usually have larger particles after crushing. After the pulverized material is sieved through a 5-200 mesh screen (6), a coarse-grained pulverized body part (7) and a fine powder part (11) mainly consisting of iron and a small amount of copper foil and aluminum foil are obtained. The particle size of the iron-nickel alloy plate in the nickel-hydrogen/nickel-cadmium battery, the positive electrode coating material and the positive electrode active material of the lithium ion battery is small after pulverization, and this part belongs to the fine powder (11).

The coarse-grained pulverized body part (7) can easily separate the iron shell scraps (9) and non-magnetic materials (10) with the help of the magnetic separation unit (8) under a magnetic field of 500-1500G, and the non-magnetic material part can be According to the content of copper foil and aluminum foil, eddy current sorting equipment is used for sorting.

The fine powder (11) obtained through sieving (6) can directly enter the first-stage corrosion system (13), the corrosion condition is 3-9N sulfuric acid (12), and the liquid-solid ratio is 20-5. It is the dissolution of cadmium metal. The filtered cadmium ion solution (14) can be used to remove the alkali gold and alkaline earth metal ions in the ion exchange resin unit, and then evaporate the water in the purified aqueous solution at 80° C. to obtain cadmium sulfate (16) crystals (15). The cadmium (16) sulphate crystals are separated from the concentrated solution by filtration, and the concentrated solution is used as part of the sulfuric acid (19) used in the second stage of erosion (20) below.

The residue (17) after the first-stage corrosion (13) enters the second-stage corrosion (20) to dissolve metals such as nickel and cobalt. The conditions for dissolution are 4-12N sulfuric acid (19), and the liquid-solid ratio is 20-5 is better. Hydrogen peroxide (18) can be added during corrosion at this stage to increase its redox potential value and improve the corrosion capacity of the system. Insoluble matter (22) such as carbon is removed by filtration (21). In the presence of hydrogen peroxide, it can be ensured that iron and aluminum ions exist in the trivalent state in the filtrate. Therefore, before entering the electrolysis system, the iron and aluminum can be separated into hydrogen by adjusting the pH value (23) to more than 3 Species of iron oxide (24) and aluminum hydroxide (25) were precipitated and isolated to fairly low concentrations. In the present invention, sodium hydroxide and sulfuric acid are used as regulators of the pH value, so that the sodium sulfate component required for the subsequent cobalt/nickel electrolysis can be produced at the same time. In the precipitation process of adjusting the pH value, the rare earth metal elements will first form a precipitate and be effectively recovered at a relatively low pH value, which is quite distinct from iron hydroxide (24) and aluminum hydroxide (25).

After removing most of the iron and aluminum impurities, the metal ion solution rich in nickel and cobalt can be extracted with 20-40% (in kerosene) alkyl or aromatic substituted phosphoric acid extractant (such as bis(-2-ethylhexyl) ) Phosphoric acid (di-2-ethylhexylphosphoric acid referred to as D2EHPA), which can be purchased from Japan's DAIHACHI company) carries out the first-stage extraction (27) in the pH range of 0 to 4, and removes cadmium, iron, and zinc doped therein in advance And manganese metal ion ion (28). After extraction, the aqueous phase containing nickel and cobalt is then replaced with 20-40% (in kerosene) alkyl or aryl-based extractant of phosphoric acid, phosphonic acid, phosphinic acid or pyrophosphoric acid (such as bis(-2- Ethylhexyl) phosphate (D2EHPA), bis-2-ethylhexyl phosphonic acid (bis-2-ethylhexyl phosphonic acid) (PC88A ^TM , available from Japan's DAIHACHI company) or bis (2,4,4- Trimethylphenyl) phosphate (bis (2,4,4-trimethylphenyl) phosphinic acid) (Cyanex272 ^TM , available from CYANAMID company) in the pH environment of 3 ~ 9, the second stage of extraction (29) will Cobalt/nickel separation. The cobalt present in the organic phase is stripped before electrolysis. The stripping agent used for the stripping is 0.4-2.0N sulfuric acid.

After adjusting the pH value of the purified cobalt/nickel sulfuric acid aqueous solution to 2-7, electrolytic units (30, 32) are used to recover high monovalent cobalt/nickel in metal form (31, 33). The optimal operating conditions of the electrolysis unit are shown in the table below. Metal Electrolyte composition (g/L) Current density mA/cm ² Tank voltage Volt Operating temperature °C Current efficiency (%) cobalt Cobalt sulfate (150~200) Sodium sulfate (100~150) Sodium chloride (15~20) Boric acid (10~30) 15～20 1.5～4.0 60 ~80 nickel Nickel sulfate (150~200) sodium chloride (15~20) boric acid (10~30) 15～20 1.5～4.0 60 ~98

The electrolyte solution after electrolysis of nickel is an aqueous solution rich in lithium ions, and carbonate can be directly added to form lithium carbonate to effectively recover lithium. The organic phase containing metal ions of cadmium, iron, zinc and manganese produced in the first stage extraction (27) is back-extracted with 0.2-1.0N sulfuric acid or hydrochloric acid aqueous solution, and the acid aqueous solution after the back-extraction is passed through ion exchange resin or Precipitation (38) can be used to remove the metal ions and discharge (39).

Description of drawings

FIG. 1 is a flow block diagram of a preferred embodiment of the method of the present invention.

Detailed ways

Example

Take 1 kg of lithium-ion battery, nickel-metal hydride battery and nickel-cadmium battery each, and the metal composition of each battery is shown in Table 1. Non-metallic substances include carbon, plastic packaging, anion parts in metal compounds, organic matter, and water.

Table 1 Metal component content of various batteries (g) metal composition Lithium Ion Battery NiMH batteries Nickel-cadmium batteries cadmium 0 0 200.1 cobalt 199.3 23.6 17.4 lithium 22.6 0 0 copper 65.4 0 0 aluminum 52.2 4.4 0 iron 214.4 205.2 304.4 manganese 0.7 25.2 0 nickel 7.0 244.3 152.4 zinc 0 2.8 0 rare earth 0 87.8 0 non-metal 438.4 406.7 325.7

After these batteries were mixed, holes were drilled to avoid explosion due to excessive internal pressure during firing. The organic substances in the mixed batteries were decomposed by roasting at 350°C (4Hr), and a total of 426 grams of organic substances and water were lost. The battery was crushed with a 5-mesh pulverizer and the pulverized body was sieved with a 20-mesh sieve. During the pulverization and sieving process, the mixed battery lost a total of 58 grams of powder. After sieving, 1096 grams of oversize (coarse-grained pulverized body) and 1420 grams of undersize (fine powder) can be obtained. After analysis, the main components of each part can be obtained as follows (Table 2):

Table 2 Composition of each part of crushed body after sieving metal composition Coarse-grained pulverized body fine powder cadmium 12.76 161.55 cobalt 20.23 193.15 lithium 7.17 14.98 copper 58.67 4.43 aluminum 49.02 5.49 iron 652.16 26.69 manganese 3.39 23.45 nickel 73.14 272.61 zinc 0.14 2.32 Nd 0 40.80 lanthanum 0 45.15 non-metal 219.25 629.40

The coarse-grained pulverized body is sorted by a magnetic separator under a magnetic force of 1100G, and 780 grams of iron with a quality of more than 80% mainly composed of iron shells can be recovered. The composition of 296 grams of non-magnetic material after magnetic separation is mainly 54% carbon, 18.7% copper foil and 15.5% aluminum foil. The copper/aluminum metal can be further separated from the carbonaceous part by gravity separation, and the obtained copper-aluminum foil mixture can be separated and recycled by an eddy current separator to obtain high-grade copper foil and aluminum foil.

As for the fine powder part, 1M 9L sulfuric acid is used for the first stage of selective dissolution, and the dissolution time is about 10 minutes for filtration. The dissolution rate of each metal in this stage is shown in Table 3. The obtained filtrate rich in cadmium sulfate is evaporated to remove water at 80° C. after removing alkali gold and alkaline earth metal ions therein through an ion exchange resin unit, and can obtain cadmium sulfate crystals and concentrated sulfuric acid aqueous solution (volume It is about 40% of the filtrate before water evaporation).

After the first stage of selective dissolution and dissolution of metal cadmium, the main metals in the powder are dissolved with 4M 6L sulfuric acid and 3% hydrogen peroxide (0.5L) (the time is about 1 hour), and the dissolution of each metal The effect is shown in Table 3. After filtering, the pH value of the solution is adjusted to 2 with sodium hydroxide, and the rare earth metals in the solution can be completely (98%) recovered by forming hydroxide precipitates. Continue to increase the acidity and alkalinity of the solution to 6, which is beneficial to the subsequent extraction and purification, and secondly, some iron ions (20%) and most (99%) aluminum ions in the solution can form hydroxide precipitates and be separated. achieve the effect of purification.

Table 3 Dissolution effect of main metals metal composition The dissolution rate of the first stage The second stage dissolution rate cadmium 93.36% 100.00% cobalt 8.11% 93.16% lithium 27.84% 100.00% copper 7.45% 2.03% aluminum 44.37% 81.25% iron 14.40% 72.09% manganese 46.24% 74.00% nickel 5.56% 88.82% zinc 49.30% 20.93% lanthanum 10.19% 93.56% Nd 10.06% 100.00%

Then, the sulfuric acid solution rich in cobalt, nickel and a small amount of cadmium is separated and purified by extraction. First use kerosene to make D2EHPA extractant into an extract with a concentration of 25%, and adjust the pH of the solution to 3 under the condition of O/A ratio of 1, so that cadmium, iron, zinc and manganese can be extracted into the organic phase and Separated from the aqueous phase rich in cobalt and nickel ions. Then, the aqueous phase rich in cobalt and nickel ions is extracted with Cyanex272 extractant in kerosene at a concentration of 0.5M, and the O/A ratio is 1, and the pH of the aqueous solution is adjusted to 6.7 with NaOH for extraction. Cobalt (organic phase)/nickel (aqueous phase) separation. The organic phase containing cobalt is back-extracted with 0.5M sulfuric acid to obtain an aqueous solution of sulfuric acid containing cobalt ions. The composition of the cobalt and nickel aqueous solution obtained after cobalt/nickel separation is shown in Table 4.

Table 4 Composition of cobalt and nickel aqueous solution after extraction and separation metal composition Cobalt aqueous solution (%) Nickel aqueous solution (%) cadmium 1.3 0.3 cobalt 94.4 1.3 iron 1.3 0 manganese 0.9 0 nickel 2.1 98.4

Add 2% boric acid to the obtained cobalt and nickel aqueous solutions respectively, control the pH value above 4, and carry out lithographic electrolysis at an electrolysis voltage of 3.5 volts. When the metal concentration of the aqueous solution is reduced to below 500ppm, in order to improve the current efficiency of electrolysis, the aqueous solution is introduced into a fluidized electrolytic cell to continue electrolysis, and the cobalt/nickel can be completely recovered. In this example, about 204 grams of metallic nickel and about 154 grams of cobalt can be recovered.

Claims (6)

1. method that reclaims valuable metal from useless secondary cell, should comprise lithium ion battery, Ni-MH battery and nickel-cadmium cell by useless secondary cell, wherein should useless secondary cell produce the grey shape thing of a containing metal and metal oxide via roasting and screening, this method comprises the following step:

A) should ash shape thing with 2 equivalent molar concentration to the 6 equivalent molar concentration aqueous sulfuric acid corrosions that contain hydrogen peroxide;

B) alkali is added the corrosion solution that step a) produced, and make wherein cadmium, rare earth ion produce crystallization;

C) mixture solid-liquid separation step b);

D) with first organic extractant resulting aqueous solution of step c) is extracted, and produce the organic layer that is rich in the water layer of nickel and cobalt ions and is rich in cadmium, iron and zinc ion;

E) with second organic extractant resulting water layer of step d) is extracted, and produce the water layer that is rich in the organic layer of cobalt ions and is rich in nickel ion;

F) this is rich in the organic layer of cobalt ions with the aqueous sulfuric acid back extraction, and produces the water layer that is rich in cobalt ions;

G) use one to carry out electrolysis with the resulting water layer that is rich in nickel ion of step e) as electrolyte, so on a negative electrode, restore the nickel metal between 1.5～4.0 volts voltage;

H) use one to carry out electrolysis with the resulting water layer that is rich in cobalt ions of step f) as electrolyte, so on a negative electrode, restore the cobalt metal between 1.5～4.0 volts voltage; And

I) carbonate of a water soluble is incorporated in electrolyte after the step g) electrolysis, and forms the precipitation of lithium carbonate;

Wherein:

First organic extractant is the phosphoric acid extraction agent that alkyl or aromatic radical replace; Second organic extractant is the extractant of phosphoric acid, phosphonic acids, phosphinic acids or the pyrophosphoric acid of alkyl or aromatic radical replacement.

2. the method for claim 1, wherein step a) and b) merge and comprise:

A1) should ash shape thing with the aqueous sulfuric acid corrosion of 2 equivalent molar concentration to 6 equivalent molar concentrations;

A2) mixture solid-liquid separation step a1);

A3) to contain 4 equivalent molar concentration to 12 equivalent molar concentration aqueous sulfuric acid corrosion step a2 of hydrogen peroxide) solid that produced;

B1) with step a2) a part of water evaporation in the corrosion solution that produced removes, has the cadmium sulfate crystallization and is its main sediment partly and obtain one;

B2) alkali is added step a3) the corrosion solution that produced, have rare earth metal hydroxide, Fe (OH) and obtain one ₃And Al (OH) ₃Be main sediment partly,

Step b2 wherein) mixture that is produced is used as the mixture of step c) Separation of Solid and Liquid.

3. method as claimed in claim 2, wherein step b2) alkali be NaOH, and the consumption of this NaOH makes that the pH value of solution value is 6.

4. method as claimed in claim 2, wherein step b1) mixture that produced is by Separation of Solid and Liquid, and the liquid that Separation of Solid and Liquid obtained is used as step a3) the part of 4 equivalent molar concentration to 12 equivalent molar concentration aqueous sulfuric acids.

5. the method for claim 1, wherein step I) water soluble carbonate be sodium carbonate.

6. the method for claim 1, it further comprises with the organic layer that is rich in cadmium, iron and zinc ion in the aqueous sulfuric acid back extraction step d), and obtains being rich in the water layer of cadmium, iron and zinc ion; And remove cadmium, iron and zinc ion in this water layer with ion exchange resin.

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