Dong-Hyo Yang

Recycling of spent lithium-ion battery cathode materials by ammoniacal leaching.

As the production and consumption of lithium ion batteries (LIBs) increase, the recycling of spent LIBs appears inevitable from an environmental, economic and health viewpoint. The leaching behavior of Ni, Mn, Co, Al and Cu from treated cathode active materials, which are separated from a commercial LIB pack in hybrid electric vehicles, is investigated with ammoniacal leaching agents based on ammonia, ammonium carbonate and ammonium sulfite. Ammonium sulfite as a reductant is necessary to enhance leaching kinetics particularly in the ammoniacal leaching of Ni and Co. Ammonium carbonate can act as a pH buffer so that the pH of leaching solution changes little during leaching. Co and Cu can be fully leached out whereas Mn and Al are hardly leached and Ni shows a moderate leaching efficiency. It is confirmed that the cathode active materials are a composite of LiMn2O4, LiCoxMnyNizO2, Al2O3 and C while the leach residue is composed of LiNixMnyCozO2, LiMn2O4, Al2O3, MnCO3 and Mn oxides. Co recovery via the ammoniacal leaching is believed to gain a competitive edge on convenitonal acid leaching both by reducing the sodium hydroxide expense for increasing the pH of leaching solution and by removing the separation steps of Mn and Al.

Resynthesis of LiCo1−xMnxO2 as a cathode material for lithium secondary batteries

A recycling process involving chemical, mechanical, and electrochemical steps has been applied to recover cobalt from spent lithium ion batteries and resynthesize cathode active materials. LiCo1−xMnxO2 powders using Co salt including Mn from the leach liquor were resynthesized by solid-state reaction as cathode active materials. When the powder mixture with added Li salt was calcined at 950 °C for 8 hours, well crystallined LiCo1−xMnxO2 was successfully obtained. The LiCo1−xMnxO2 powders with a ratio of Co:Mn=10:1 has a discharge capacity of 156.3 mAh/g at a rate of 20 mA/g with no perceptible capacity loss, in sharp contrast to the pure LiCoO2 as active materials. The resynthesized LiCo1−xMnxO2 was proven to have good characteristics as cathode active materials in charge/discharge capacity and cyclic performance.

Comparison of Acid and Alkaline Leaching for Recovery of Valuable Metals from Spent Zinc-carbon Battery

ABSTRACT The spent zinc-carbon batteries are composed of approximately 20% of Mn, 20% of Zn, magnetic materials and small amounts of carbon, plastics and electrolyte. Some of zinc metals in the spent battery reacted into zinc oxides and some of MnO2 reduced into Mn2O3 after discharging reaction. In this study, acid and alkaline processes of spent zinc-carbon battery are proposed and there performances are compared. In case of H2SO4, the results of zinc and manganese dissolution rates obtained by adding H2O2 were 93.3% and 82.2%, respectively at 100g/L solid/liquid ratio, 2.0M H2SO4, 60 °C and 200 rpm. In case of NaOH, the results of zinc and manganese dissolution rates obtained at 100g/L solid/liquid ratio, 4M NaOH, 80 °C and 200 r.p.m. were 82% and below 0.1% respectively. Therefore, the efficiency of selective extraction of Zn was very high.

Recovery of Cobalt in Sulfuric Acid Leaching Solution Using Oxalic Acid

ABSTRACT Oxalic acid was used for recovering cobalt from leaching solution of spent lithium ion battery by precipitation method. Crushed powders containing LiCoO2 of spent lithium ion battery were obtained by crushing, magnetic separation and screening process. These powders were dissolved in 2 M H2SO4 solution with H2O2 as a reducing agent. After dissolving Co and Li components, the solution of oxalic acid was added. Co(II) in leaching solution could be removed in the form of insoluble oxalates. The precipitate formed was crystalline, compact and easily filtered. With the increase in oxalic acid, the rate of cobalt precipitate increased to 90% at 1:4 mole ratio of Co(II) and oxalic acid concentration. When cobalt ion was precipitated into cobalt oxalate, nickel and copper ions were co-precipitated but there were no co-precipitates of Li, Al and Fe. The amounts of Ni and Cu in the solutions were below 1%. After heat treatment of precipitates at above 250°C, cobalt oxalate was changed into cobalt oxide.

Comparison of Two Acidic Leaching Processes for Selecting the Effective Recycle Process of Spent Lithium ion Battery

ABSTRACT Physical treatment and chemical treatment of spent lithium-ion battery were studied in our research team. Especially we developed two types of acidic leaching for crushed powders containing LiCoO2 of spent lithium ion battery. One of them is sulfuric acid leaching with H2O2 as a reducing agent. The leaching rates of cobalt, lithium and the other metals were above 99 % at the condition of 2 M H2SO4, 10 vol. % H2O2, 75°C, 300 rpm agitation speed, 250 g/5L solid liquid ratio and 75 minutes reaction time. And the other leaching process is the oxalic acid leaching. In this process more than 99% of Li and less than 1% of Co were dissolved at the condition of 3M oxalic acid, 80°C reaction temperature, 300rpm agitation speed, 50g/L initial solid/liquid ratio and 90min extraction time. Each process has its advantage and disadvantage. In sulfuric acid leaching, leaching reagent is very cheap and cobalt could be recovered into cobalt hydroxide. On the other hand, oxalic acid is more expensive than sulfuric acid but lithium could be dissolved selectively. Also cobalt could be recovered into cobalt oxalate and it could be changed into cobalt oxide after heat treatment. In order to select the effective recycling process, recovery rate and purity of cobalt hydroxide and cobalt oxalate were compared and it was investigated which process was more environment-friendly and economical.

Efficient recycling of WC-Co hardmetal sludge by oxidation followed by alkali and sulfuric acid treatments

We present a process to recycle strategic metals, viz. tungsten and cobalt, from a WC-Co hardmetal sludge (WCHS) via oxidation followed by a two-step hydrometallurgical treatment with alkali and acid solutions. The oxidation of WCHS was investigated in the temperature range of 500 to 1000 °C and optimized at 600 °C to transform the maximum WC into an alkali-soluble WO3. The conditions for the selective dissolution of WO3 in stage-I were optimized as follows: 4.0 M NaOH, pulp density of 175 g/L, and temperature of 100 °C for 1 h, yielding maximum efficacy. Subsequently, in the second step, the optimal conditions for cobalt leaching from the alkali-treated residue were established as follows: 2.0 M H2SO4, 25 g/L pulp density, and 75 °C temperature for 30 min. Downstream processing of the obtained metal ions in solutions was also easier, as the only impurity of dicobaltite ions with the Na2WO4 solution was precipitated as Co(OH)3 under atmospheric O2; meanwhile, the CoSO4 solution obtained through the second step of processing can be treated via electrolysis to recover the metallic cobalt. The present process is simpler in operation, and the efficient use of eco-friendly lixiviants eliminates the previously reported disadvantage.

A new approach to the recycling of gold mine tailings using red mud and waste limestone as melting fluxes

Gold mine tailing, red mud and waste limestone cause very serious problems to the environment. Due to their abundant amount of waste as well as difficulties with disposal, an appropriate recycling technology of this waste is necessary to mine and smelting industries. As a prospective process for treating a large volume of the waste, slag atomizing technology is developed. Slag composition is the most important factor in manufacturing slag granules. The waste was mixed with the ratio of 26 wt% of tailing, 38 wt% of red mud and 36 wt% of waste limestone for a better melting operation regarding product property, viscosity and melting temperature. After pelletizing the above mixture, the pellets were dried in an oven for 2 days and were melted in an electric arc furnace at 1500(C for 2 hours. Separated slag was atomized under air gas surrounding with the velocity of 75 m/second. The final obtained precious slag balls might have good physical properties, such as highly spherical shape and narrow size distribution for application in abrasives, roofing granules, polymer concrete and road paving materials.

Production of Ceramic Balls by High Temperature Atomization of Mine Wastes

Gold tailing, red mud and waste limestones are industrial wastes that are mostly landfilled near the process plants. These increase the environmental risks as well as the necessity of waste management. Recycling of materials has been limited due to the fine particle sizes, heavy metals and unique oxide compositions. The authors investigated the potential utilization of these industrial wastes by melting and granulation technique. As quartz, hematite, alumina and lime consist more than 90wt% of mine wastes, CaO-FetO-Al2O3-SiO2 quaternary oxide system was applied to the thermodynamic calculations. Compositions of molten oxides were designed considering the lowest melting temperature and the adequate viscosity for atomization. Samples were melted by high frequency induction furnace then the atomization was carried out by air blowing technique. Viscosities of the melts were measured to quantify the optimum melting and atomization condition. Size distribution of the produced ceramic balls was investigated to estimate potential of the product to be used as abrasive materials.

Study of Physical Treatment of Spent Military Use Lithium Primary Batteries for Recycling

ABSTRACT Physical treatment of lithium primary batteries without explosion is required to recycle the lithium primary batteries which could be exploded by heating too much or crushing. The safe dismantlement method of the spent lithium primary batteries has been required to recycle the batteries because the batteries contain lithium metal although the batteries are discharged. In the present study, safe dismantlement of the spent batteries was investigated, and then feasibility study was performed to recycle scraps of the spent batteries. As written above, the batteries were safely crushed, and metals such as nickel were recovered. Further study was required to increase recovery ratio and purity of metal.