CHARACTERIZATION OF GOLD ORE FROM POBOYA BLOCK CENTER SULAWESI AND STUDY OF EXTRACTION BEHAVIOR ON CYANIDATION PROCESS

• Main Author: Yoseva Purba, Janres
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62070
• Institution: Institut Teknologi Bandung

Indonesia has gold deposit that spread in various areas which has been mined or not yet. Characteristics of the gold ore varies from one place to others depends on genesis of the gold deposit and it has strong correlation with its suitable processing route. In this research, characterization of gold ore from Poboya block provided by PT. Citra Palu Minerals and cyanidation experiments with variatons of gold ore domain and grade, concentrations of cyanide (NaCN) and dissolved oxygen (DO) as well as ore size was performed. Series of Carbon-in Leach (CIL) test were also conducted by using granular activated carbon. This investigation began with sample preparation by size reduction through crushing and grinding. Ore characterization is done by assaying gold headgrade using Fire Assay method, chemical composition analysis by ICP, carbon and sulphur content measurement by LECO analysis, and gold size-by-size assay to determine gold particle size distribution. Mineral identification was done by XRD and mineragraphic analysis. Investigations for preg-robbing potential measurement of the gold ore refer to Goodal et.al. experiment. Cyanidation testworks were carried out at variations of the ore domain namely Wall Rock (WR), Mein Vein (MV), and Dilution (DIL) and ore grade namely High Grade (HG), Medium Grade (MG), and Low Grade (LG) as well as the composite of those six ore sample types. Cyanide concentration was varied at 1000 and 2000ppm, while DO concentration was varied at the range of 7-9 ppm and 15-20 ppm. Ore size was varied at p80 200# and 325#. CIL testwork uses cactivated carbon dosage of 10 gram per litre slurry. Ore characterization revealed that gold from Poboya Block, Central Sulawesi is low sulfide type epithermal vein with most dominant mineral of Quartz. The ore has low content of sulfide mineral in the forms of chalcopyrite, sphalerite, and pyrite. The ore has low potential of preg-robbing with the average of 7.4% during 24 hour of cyanidation test. The composite ore has the highest gold fraction of 0- 50 micron (41%), followed by >150 micron (27%), and <20 micron (6%). Result of cyanidation test indicated that the gold ore from Poboya Block with domain of Mein Vein (MV), and High Grade (HG) is a free-milling type that demonstrates gold extraction level of >90% at NaCN concentration of 1000 ppm, DO 7-9 ppm, and ore size of p80 200#. Ore size reduction from 200# to 325# enhanced gold extraction of composite ore from 90.25% to 92.48%. Results of CIL test showed the adsorption and total recovery percentages of 99%, respectively that indicates CIL method is suitable to treat the gold ore from Poboya block, Palu.