CHARACTERIZATION STUDY OF ALLUVIAL GOLD ORE CONTAINING HIGH IRON FROM MIMIKA DISTRICT PAPUA BY DIAGNOSTIC LEACHING AND PULVERIZED BOTTLE ROLL TEST METHODS

• Main Author: RANU SIRSYAH (NIM : 12514025), HANAJIT
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/27669
• Institution: Institut Teknologi Bandung

The decline of free milling gold ore reserve in Indonesia has encouraged mining and processing companies to treat another types of gold ore. Alluvial gold deposit is one of alternative gold ore types that can be processed. PT Papua Fajar Timur is a gold mining company which has a mining concession in Mimika District, Papua, and currently is conducting a study to develop processing route of the ore deposit in it’s consession area. This stage is carried out to find out the type and characteristic of gold ore that will be treated and determining the best processing route based on metallurgical testing in laboratory. In this research characterization study was conducted for alluvial gold ore containing high iron recieved from Pt PFT through a series of diagnostic leaching, size by size assay and pulverized bottle roll test. <br /> <br /> The experiments began with preparation ore sample which includes drying, homogenization, pulverizing and sampling by using rotary splitter. Determination of gold grade (head grade) is done by fire assay, while ore chemical composition was determined by ICP analysis. Size by size assay was then carried out to find out gold size distribution in the ore. Mineral characterization was conducted by SEM+EDX and XRD analyses. Diagnostic leaching test consists of several leaching stages which include cyanide leaching (24 hours), cyanide washing (30 minutes), acid leaching by HCl and HF (8 and 6 hours). Pulverized bottle roll test was carried out by varying ore particle size distribution at P80 74&#956;m (-200 mesh) and P80 37&#956;m (-400 mesh), slurry density at 33.33% and 40% solid, cyanide concentration at 750 and 2000 ppm, and dissolved oxygen concentration at 7-9 and 15-20 ppm. <br /> <br /> The XRD analysis, head assay, and ore chemical composition analysis results showed that gold ore type recieved from Mimika District, Papua use in this study is alluvial oxides which contains mostly iron of 58.68%, silica of 5.48%, and gold content of 6,46 g/ton. Diagnostic leaching test results indicated that 62,716% of total gold is free gold, 8.287% is within the iron oxide minerals, 7.630% is within silica, and 21.366% fine gold in complex oxide minerals. Size by size assay result showed that 28.29% of total gold has size fraction of 149 &#956;m (+100 mesh), 19.10% has size fraction of 74 &#956;m (+200 mesh) and 48.39% has finer sizes (-200 mesh). The pulverized bottle roll test resulted in the highest gold extraction of 77.03% and 76.79%, which were obtained at P80 37 &#956;m (P80 400 mesh) and P80 74 &#956;m (P80 200 mesh), respectively.