STUDY OF THE EFFECT OF BIOOXIDATION OF GOLD WASTE MINERAL ON GOLD RECOVERY THROUGH CYANIDATION USING IRON AND SULFUR OXIDIZING BACTERIA

• Main Author: ANUGRAH (NIM : 12514005), NURAH
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29760
• Institution: Institut Teknologi Bandung

Waste mineral is ore or mineral part of overburden precisely in the core soil layer which is still considered to contain valuable minerals but at very low level. The waste mineral used in this study is still contain gold. However, the gold content is very small and the presence of impurity minerals such as carbonate minerals, clay minerals and sulfide minerals can be obstacle in processing the ore. The biooxidation pre-treatment method has been an alternative method of refractory gold ore pre-treatment because it has been technically proven to be an economical and environmentally friendly method. In this study, biooxidation experiment on gold waste mineral were carried out using iron and sulfur oxidizing bacteria. <br /> <br /> The series of experiments were begun with ore preparation with grinding then proceed with sieving to obtain ore with 200 mesh size (-200 #) or 75 microns (-75 &#956;m). Furthermore, the ore is homogenized and sampled by riffle splitter and coning-quartering methods for the purpose of ore sample characterization and also biooxidation experiments. The characterization of the ore carried out are XRD, XRF, mineragraphy analysis, head grade analysis and testing of preg-robbing properties. Then the preliminary biooxidation experiment was carried out on ore with iron and sulfur oxidizing bacteria which aims to determine the best bacteria in the experiment and conduct cyanidation experiments directly on ore without biooxidation treatment which aims to determine how much influence the biooxidation step on increasing the percentage of gold extraction. After obtaining the best bacteria, a core biooxidation experiment will be carried out using the best bacteria with several variations in the biooxidation process which include variations in the addition of iron sulfate, molasses and percent padatans. Then, cyanidation experiments were carried out on each biooxidation residue using agitation leaching with 30% Padatan, 1000 ppm NaCN concentration, pH 10.45-10.5, dissolved oxygen concentration 7-10 ppm for 24 hours. <br /> <br /> The results of the analysis showed that the gold ore contained carbonate minerals and the ore has preg-robbing properties with medium category. The best iron and sulfur oxidizing mixotrof bacteria according to the experiment is Pantoea Septica with percentage of gold extraction is 45.52%. The result of gold recovery of direct cyanidation is 30.60%. Variations in the addition of reagents showed the highest percentage of gold extraction was obtained with the addition of 20 g/l iron sulfate, 4 g/l molasses, and 5% padatan with an extraction percentage of 49.82%.