STUDY OF FLUORIDE CHARACTERISTIC ON PORPHYRY - SKARN CU-AU, DMLZ UNDERGROUND MINES, PAPUA, INDONESIA

• Main Author: Wulandari, Asri
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/79574
• Institution: Institut Teknologi Bandung

The Deep Mill Level Zone (DMLZ) is part of the East Ersberg Skarn System (EESS) ore deposit. The alteration types developed in this prospect area are porphyry and skarn types with copper grades of 0.85%and gold of 0.72g/ton . The porphyry deposits are characterized by the multiple intrusion of quartz diorite and monzodiorite. The contact metamorphism process also occurs due to intrusions that breakthrough limestone and dolomite. It is characterized by the presence of siliciclastic minerals in the surrounding area. Skarn deposits also formed in this area, characterized by the presence of skarn minerals such as anhydrite and magnetite. This study was conducted to identify the characteristics and distribution of fluoride in the DMLZ. The presence of high content fluoride should be problems during Cu-Au concentrate ore processing and selective separation by flotation. This study utilized 467 drill data and 11 rock samples from the DMLZ underground mine. The analytical methods used consisted of fire assay, X-ray Dif raction (XRD), and Ion Selective Electrode (ISE) methods. The analytical results of the samples from the underground mine were then correlated with the borehole data that had been validated in advance to obtain more accurate correlation results. Based on the analysis, the highest fluoride levels are associated with lithological contact and skarn alteration. The highest fluoride content was found at the lithological contacts between diorite intrusion and dolomite of 1730-2070 ppm. Meanwhile, the highest fluoride also found in chlorite-garnet-anhydrite (exoskarn) alteration zone with average fluoride content of 2170 ppm, and 1270 ppm at the diopsid-garnet-epidote alteration zone. On the other hand, the correlation limit for fluoride with base metals is between -0,3 and 0,4. Therefore, the recommendation before processing Cu-Au ore, it is best to separate the type of skarn alteration material first because it is likely to produce quite high levels of fluoride.