BIOOXIDATION EFFECT OF BANYUWANGI GOLD ORE ON GOLD RECOVERY THROUGH CYANIDATION USING THE BACTERIUM Comamonas testosteroni STRAIN SKC/SAA-1

• Main Author: Denny Saputra, Rachmat
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40163
• Institution: Institut Teknologi Bandung

Gold is one metal that has many uses in everyday life. The utilization of gold includes the manufacture of jewelry, electronic goods, and as an investment because of its increasing value. Not all gold ores can be directly processed economically. Refractory gold ore requires a pre-treatment process beforehand so that it can be processed economically. Biooxidation is an alternative pre-treatment for refractory gold ore which has been proven to be more economical and environmentally friendly. In this study, biooxidation experiment was conducted on gold ore originating from Banyuwangi using iron-and sulfur-oxidizing bacteria. A series of experiments have been carried out to investigate the effect of the biooxidation process, started with the ore preparation which included crushing and grinding to obtain the particle size of 200 mesh (75 ?m). The ore was homogenized and sampling was performed for characterization and biooxidation experiments. Characterizations were XRD, XRF, mineragraphy, head grade analysis, diagnostic leaching analysis, and FTIR. Prior to biooxidation experiments, the bacterial growth curve was constructed to determine the optimum incubation time of bacteria, followed by a preliminary biooxidation experiment to decide the most optimum iron-and sulfur-oxidizing bacterium for the main biooxidation experiments. In parallel, direct cyanidation was also performed to the ore without biooxidation as a comparison. The main biooxidation experiments were carried out with several variations: biooxidation medium, bacterial inoculum concentration, and biooxidation time. Subsequently, cyanidation of the residual biooxidation process was conducted by using 1000 ppm NaCN solution at 30% pulp density for 24 hours and followed by aqua regia of the residual cyanidation process. The analysis showed that gold ore from Banyuwangi was refractory gold ore with direct cyanidation extraction of 27.32%, while impurities were found as quartz (SiO2), galena (PbS), and siderite (FeCO3). It was observed that the optimum incubation time of bacteria was approximately 19.2 hours. The most optimum iron-and sulfur-oxidizing bacterium in the preliminary biooxidation process was Comamonas testosteroni strain SKC/SAA-1. Under the most optimum biooxidation conditions, gold extraction was able to enhance significantly up to 57.42% by using modified SKC-broth medium with the composition of seawater, 4 g/l molasses, 2 g/l FeSO4.7H2O, and 9 g/l pyrite (FeS2), pH adjustment to 1, 10% (v/v) bacterial inoculum, and 7 days of biooxidation process.