MMIJ & EARTH 2017

政翰

Recovery of high-purity lithium carbonate from lithium-ion batteries cathode material

In nowadays, in response to current market having the high requirement and application level for lithium-ion batteries, the demands of lithium carbonate are rising increasingly. Now, lithium carbonate are mainly used in the glass and ceramics manufacture process as fluxing agent, additive agent and also used as preparation of various lithium compound. With the current research and development, high-purity lithium carbonate which purity over than 99.9% are applied to preparation of lithium-ion batteries cathode material and electrolyte raw material. In the aim of achieving material recycling, in this study, we will focus on recovery of lithium which is leached in sulfuric acid and trying to prepare lithium carbonate by chemical precipitation and promote it’s purity to obtain high-purity lithium carbonate. Finally, high-purity lithium carbonate can be used to preparation of lithium-ion batteries again.

弼程

Using ion-exchange resin to recovery of germanium from waste optical fibers

Germanium tetrachloride and germanium dioxide which used in optical fiber demand rises significantly due to the rapid development of optical fiber communication in recent years. It has 3% germanium in the optical fiber that is enough high to recycle them. In this study, we use ion-exchange to separate germanium (IV) from high concentration of silicate ion selectively which is 30 times more than germanium. Germanium in solution was recovered on an anion-exchange resin after complexation with catechol. Experiment investigations were undertaken using quaternary ammonium resins: IRA-900 and IRA-958. The influence of pH, time and amounts of resin and catechol on the sorption capacity were investigated. We also compare the germanium adsorption efficiency without catechol because germanium in high pH value would turn to anion that the pk1 and pk2 of germanium acid is 9.01 and 12.3. According to the adsorption efficiency and leaching process, the operation at low pH value is better and more selective. And using hydrochloric acid eluted the germanium ions. The best condition of solution is at pH=6, 5 times as high as the germanium molarity of catechol, flow rate=35ml/h and use 0.1M hydrochloric acid to elute, then we can separate 99% germanium from silicate effectively. Obviously, it indicated that process was very a powerful technique for recovering germanium. Germanium (IV) is the lack of resources in the world, and it is also the scattered precious metal. Therefore, the waste optic fiber cable has recovered economic benefits and necessities.

星融

Recovery of valuable metals from lithium-ion batteries cathode material by leaching and solvent extraction

With the use and application of lithium-ion batteries (LIBs) are increasing constantly and widely, the wastes and adverse influence are generated and cause the environmental pollution. In recent years, the research about recovery of LIBs mainly focus on lithium cobalt oxide batteries and lithium manganese oxide batteries. However, those types of batteries are gradually replaced by lithium nickel manganese cobalt oxide batteries (NMC batteries). In this study, we will concentrate on dealing with waste cathode material produced during the manufacture of NMC batteries. The hydrometallurgical process will be used to recovery of valuable metals in LIBs. In leaching step, the effects of H₂SO₄ concentration, H₂O₂ concentration, leaching time, liquid-solid mass ratio and reaction temperature with leaching percentage are investigated. After leaching process is completed, the solvent extraction process, which is carried out using Cyanex 272 diluted with kerosene will separate cobalt, manganese, nickel and lithium. The factors affecting the extraction process are the effect of equilibrium pH and extractant concentration, O/A ratio, temperature. Finally, stripping of cobalt and manganese will be achieved by sulfuric acid.

振堯

Neodymium Resources Recycling from Spent Magnets Slurry

Since permanent magnet, the demand of permanent increase year by year. Permanent magnet have applied in multiple area, like wind turbine, magnetic resonance imaging (MRI), DVD players and voice coil motor (VCM). In Taiwan, the process of VCM product over 10 tons of Nd-contained slurry per year without suitable treatment. In this study, the analysis of raw material by ICP contained 24.5 wt% Nd, 71.5% Fe, 1% B. After leaching process, we will discuss the initial pH value, extractant, organic-aqua ratio and extractant concentration to get the optimal parameters to separate Fe and Nd. Next, the stripping process discuss the type of stripping agent and the concentration. In the last step, the purification process will be investigated. Using oxalic acid to obtain oxalic neodymium and after calcination process to get neodymium oxide. Finally, we could obtain over 90% recovery rate of Nd.

文誠

Leaching molybdenum from ferro-molybdenum slag

Ferro-molybdenum slags are by-product from ferro-molybdenum smelting industry. However, ferro-molybdenum slags include about 1 wt% molybdenum. Recycling ferro-molybdenum slags not only is valuable but reduces environment impact.

This study focus on physical separation methods such as crushing for screening, grinding (ball mill) for classification and attrition scrubbing for concentration and expects to increase to 2 wt% molybdenum in slags. To find out the optima parameter (different particle sizes, leaching agents, contact time and liquid to solid (L/S) ratio) for leaching and to expect molybdenum leaching rate 95%(or more). In the future, depends on this study to develop a series of ferro-molybdenum slags recycling system.

立霖

Leaching behavior of metal-organic chemical vapor deposition (MOCVD) waste of GaN

In this study , a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acid leaching. The laureates of the Nobel Prize in Physics, Nakamura Shuji, Isamu Akasaki and Hiroshi Amano, did the research about gallium nitride (GaN) doping indium and aluminum and invented the efficient blue light-emitting diodes (Blue LED). This invention was also called as the second lighting revolution because it enabled bright and energy-saving white light sources. As the research of blue LED increased in recent years, the development of white LED has become no longer dreaming. For the adaptation of this great impact and the market variation, the resources of gallium and indium will become a major issue of this lighting revolution. This study will focus on the leaching behavior of GaN-containing wastes by using different acids. Various leaching process parameters like effect of acidity, solid-liquid ratio, temperature and concentration of acids on the leaching efficiency of gallium and indium are investigated. Because the refractory GaN phase is hard to leach, using pyrometallurgy like high temperature oxidative roasting and thermal diffusion for the pre-treatment of the wastes. Combined with hydrometallurgy, such as acid leaching and the process is optimized by ICP-AES analysis. The effective optimum condition for quantitative leaching of gallium and indium is investigated.