Recovery of Gallium and Indium from Waste Light Emitting Diodes

Recovery of gallium and indium from waste light emitting diodes has been emphasized gradually owing to high content of gallium and indium. This study was established the recovery of gallium (Ga³⁺) and indium (In³⁺) from waste gallium nitride was contained in waste light-emitting diodes. The procedure was divided into the following steps; characteristic analysis, alkaline roasting, and leaching. In characteristic analysis part, the results were used as a theoretical basis for the acid leaching part, and the chemical composition of waste light emitting diodes is 70.32% Ga, 5.31% Si, 2.27% Al and 2.07% In. Secondly, with reduction of non-metallic components by alkaline roasting, gallium nitride was reacted into sodium gallium oxide, in this section, the optimal condition of alkaline roasting is that the furnace was soaked at 900℃ for 3 hours with mixing Na₂CO₃. Next, leaching of waste light emitting diodes was extremely important in the process of recovery of gallium and indium. The result of leaching efficiency was investigated on the optimal condition accounting for the acid agent, concentration of acid, the ratio of liquid and solid, and reaction time. The optimal condition of leaching procedures was carried out for 2.0M of HCl liquid-solid mass ratio of 30 ml/g in 32minutes at 25℃ and about 96.88% Ga and 96.61% In were leached.

발광다이오드는 많은 양의 갈륨과 인듐을 함유하고 있어, 폐발광다이오드로부터 이들 원소의 회수는 최근 많은 관심을 받은 연구 분야이다. 본 연구에서는 폐발광다이오드에 포함된 질화갈륨으로부터 갈륨과 인듐을 회수하고자 시도하였다. 전체 공정은 물성분석, 알칼리배소, 침출의 세 단계로 구성되었다. 화학성분 분석결과 폐발광다이오드의 경우, 70.32% 갈륨, 5.31% 규소, 2.27% 알루미늄 및 2.07% 인듐이 함유됨을 확인하였다. 두 번째 단계인 알칼리배소 공정은 탄산나트륨과 함께, 900℃하에서 3시간의 반응이 최적 조건인 것으로 확인되었고, 이 공정을 통해 질화갈륨이 질화산화물로 변화되었다. 마지막은 침출 단계로서, 산의 종류 및 농도, 고액비, 반응시간에 따른 변화를 조사하여, 최적조건을 확립하였다. 최적조건은 반응온도 25℃ 및 2.0 M의 염산 환경에서 30 ml/g의 고액비와 반응시간 32분으로 나타났으며, 그 때의 침출 효율은 갈륨 96.88%와 인듐 96.61%로 나타났다.