A REVIEW OF GOLD BIORECOVERY FROM ELECTRONIC WASTES

• Main Author: Akbar Prabowo, Billy
• Format: Final Project
• Language: Indonesia
• Subjects: Metalurgi
• Online Access: https://digilib.itb.ac.id/gdl/view/51434
• Institution: Institut Teknologi Bandung

Electronic equipment's revolutionary use gained some negative impacts, such as the massive amounts of electronic waste every year. Waste Electrical and Electronic Waste, also known as e-wastes, has great potential because it contains valuable metals, especially gold. The gold content in the e-wastes, especially in printed circuit boards (PCB), is higher than landfill gold mining. Therefore, gold recycling can reduce waste and utilize the economic value of e-wastes. Also, the environmentally friendly method of gold recycling through the biohydrometallurgical process continues to advance. Biohydrometallurgical studies will answer the challenge of reducing hazardous waste in conventional processes. The gold bioleaching study aims to learn further about several objects, namely the microorganisms involved in the leaching process, the leaching mechanisms, the leaching parameters, and the overall processes. Simultaneously, copper bioleaching was also studied because copper is the base metal in e-wastes. Copper can consume reagents during gold leaching and reduce gold purity, which is undesirable in the gold leaching process. This final project's writing process began by looking for related papers and books containing the following keywords: bioleaching, printed circuit board (PCB), e-wastes, and recycling. The research for data and information sources is limited to the literature that only discusses PCB and the copper and gold bioleaching process. After that, the next process is reading, concluding literature sources, and writing the literature studies results in this final project. Based on the literature study, copper bioleaching from PCB can use several microorganisms, namely autotrophic bacteria (iron and sulfur-oxidizing bacteria), heterotrophic bacteria, and fungi. In general, the extraction of copper happened because of several metal mobilization mechanisms, namely acidolysis, complexolysis, and redoxolysis. The copper bioleaching process can be carried out at optimum temperatures (20-45 °C) to high temperatures (45-122 °C) according to the type of microorganism used in the process. After that, the gold is extracted by cyanide producing bacteria to form gold cyanide complexes. Generally, bioleaching of copper and gold using cyanogenic bacteria occurs at 30 °C and pH 7-10.5. Bioleaching of copper using non-cyanogenic bacteria is carried out at pH 1-4. The highest recovery recorded in the copper bioleaching (99.99%) was obtained using a mixed culture of A. thiooxidans + A. ferrooxidans. In comparison, the highest recovery in gold bioleaching (73.17%) was obtained by using a mixed culture of P. aeruginosa + C. violaceum.