STUDY OF ZN AND FE EXTRACTION ON SULFIDE GOLD ORE BIOOXIDATION USING SULFUR- AND IRON-OXIDIZING BACTERIA

• Main Author: Wahyudi, Ridho
• Format: Final Project
• Language: Indonesia
• Subjects: Metalurgi
• Online Access: https://digilib.itb.ac.id/gdl/view/32357
• Institution: Institut Teknologi Bandung

Gold is one of the most well-known precious metal in our daily live. Most of gold was extracted via hydrometallurgy approaches such as cyanidation and cementation. Since the gangue minerals contained in the low grade gold ore such as sulfide is required to be eliminated, hydrometallurgy approaches might sound complicated. One of the most common method to solve this problem is by a pretreatment to the ores. In this research, biooxidation process by using Kluyvera georgina and Aeromonas schubertii were performed to evaluate the amount of gangue elements released from the ores, e.g., zinc (Zn) and iron (Fe). In the process, biooxidation followed by cyanidation were applied to the ores and residue, respectively. Series of biooxidation experiment have been carried out to investigate the profile of Fe and Zn extraction throughout the process. The experiment was started with the ore preparation by comminution. Biooxidation was conducted in 250 ml erlenmeyer flask in a rotary shaker (180 rpm; 4 days; 25oC). Several pulp densities, inoculum percentages, two bacterial species and NaCl concentrations were tested. Samples were withdrawn periodically (once every 24 hours) for analysis. Sampling parameters were pH, Eh, and total dissolved Zn and Fe. The residue obtained from biooxidation was used further for cyanidation process. Cyanidation was conducted in 250 ml beaker glass on a hot plate (500 rpm; 1 day; 25oC; pH 10-11; DO 7-10 mg/l). According to the ore characterization it was revealed that the ore was dominated by pyrite and sphalerite. The highest recovery of Zn and Fe was 38.63% and 3.989% for Zn dan Fe, respectively, achieved at 10% solid, 10% v/v Aeromonas schubertii with 30g/l NaCl addition. Low Fe recovery was due to the presence of arsenic (As) which might inhibit the activity of the bacteria. Cyanidation process has shown that biooxidation using Kluyvera georgiana resulted slight increase in gold extraction from 43.78% to 52.94%. This reasearch need more investigation to get better result before applied in industrial scale.