OPTIMIZATION OF GOLD ORE PROCESSING BASED ON STUDY OF MINERALOGICAL AND METALLURGICAL CHARACTERISTICS, CASE STUDY: PASIR SUUNG PROSPECT, CIBEBER DISTRICT, LEBAK REGENCY, BANTEN

• Main Author: Yurniadi, Feddy
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57943
• Institution: Institut Teknologi Bandung

Gold ore processing at Pasir Suung Prospect has been conducted intensively by PT Multi Utama Kreasindo (PT MUK) using carbon-in-leach (CIL) method but comprehensive study about mineralogical and metallurgical characteristics of gold ore and its effects on processing hasn’t been conducted yet. Purposes of this research are to determine the mineralogical characteristics and extraction capabilities of gold ore and to determine the optimization steps which could be implemented on gold ore processing. This research is conducted on four phases i.e., data collection, laboratory analyses, metallurgical tests, and data processing and interpretation. Collected data are gold ore samples from open pit mining at Pasir Suung Prospect, taken from quartz veins which are differentiated by vein textures. Laboratory analyses are gold assay by Fire Assay and Aqua Regia, X-Ray Fluorescence (XRF), X-Ray Diffractometry (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), and Particle Size Distribution (PSD). Metallurgical tests are Gravity Separation, Bottle Roll Leach Test (BRLT), and Diagnostic Leach Test (DLT). Gold ore from Pasir Suung Prospect is classified as quartz vein ore which is divided to two types based on dominant vein texture, i.e., massive and lattice-bladed quartz vein. Gangue minerals are dominated by quartz with minor silicate minerals such as clay minerals (illite and kaolin) and riebeckite. Ore minerals occurred as iron oxide minerals (goethite and hematite) and sulphide mineral (pyrite). Gold occurred as microscopic gold (visible gold) i.e., native gold, electrum, and kustelite. Microscopic gold is very fine to fine-grained (18-93 ?m) and generally liberated, unattached to other minerals. Another gold specimen occurred within gold ore are submicroscopic gold and coarse gold. Based on DLT result, submicroscopic gold (invisible gold) is interpreted to be associated with iron oxide minerals (goethite and hematite), sulphide mineral (pyrite), and silicate minerals (quartz and clay minerals). Coarse gold is not observed by megascopic observation, but presence of coarse gold is indicated from SEM-EDS and Gravity Separation results. Based on cyanide leaching test by BRLT method, gold ore from Pasir Suung Prospect is classified as free-milling ore with maximum gold extraction up to 82-94%. This result indicated that gold ore from Pasir Suung Prospect can be processed directly (without pre-treatment) by cyanide leaching. Mineralogical and metallurgical characteristics of gold ore that can affect processing by cyanide leaching are gold mineralogy, liberation of gold grains, and gold grain size. Other factors that could affect gold ore processing by cyanide leaching are occurrence of gangue minerals that could interfere cyanide leaching process such as cyanide consumer, preg-robber, and deleterious mineral. Those minerals are not present in this research but could be potentially present at field/mine site. Quartz vein gold ore from Pasir Suung Prospect could be processed by using series of processing tanks. PT MUK has been used CIL method to process this type of gold ore. Based on study of mineralogical and metallurgical characteristics of gold ore from Pasir Suung Prospect, we proposed four optimization steps to be implemented on processing of gold ore by cyanide leaching, i.e., grind size determination, addition of gravity concentration method, cyanide concentration control, and residence time determination. Those steps are suited to processing method used and availability of processing facility at PT MUK. Implementation of those steps in cyanide leaching test by BRLT method can increase average gold extraction at 12th hours of leaching by 14%, compared to processing result conducted by PT MUK. Further investigations to determine more detailed mineralogical and metallurgical characteristics of gold ore by more advanced analytical methods and tools and larger scale of metallurgical tests will expand and strengthen the result of this research.