STUDY OF MAGNETIZING ROASTING OF PYRITE AS A PRE-TREATMENT METHOD FOR GOLD REFRACTORY ORE: A CRITICAL REVIEW

• Main Author: Fajar Asri, Muhammad
• Format: Final Project
• Language: Indonesia
• Subjects: Metalurgi
• Online Access: https://digilib.itb.ac.id/gdl/view/51127
• Institution: Institut Teknologi Bandung

Gold refractory ore is the largest gold mineral sources for gold production. It is estimated that around 38% gold ore in the world is in the form of gold refractory ore. Pretreatment is commonly performed on this type of gold ore to increase the extraction of gold during the subsequent leaching step. One of the common pretreatment methods mostly used by the gold industries is the oxidative roasting. Although this method has been applied for many years, there are still some downsides which need to be rectified. Those problems are some sulfide/sulphate minerals that are associated with gold minerals are difficult to be oxidized and encapsulation of gold inside product calcine. One of many solutions for this problem is oxidative roasting followed by magnetic separation to separate the magnetic products from the non-magnetic gangue minerals. The aim of this research is to have a deeper understanding for the mechanism of magnetizing roasting as a pre-treatment method for gold refractory sulfide ore by analyzing the effect of roasting parameter and magnetic properties of the calcine products. The first step of this research is to gather data from journal and other type of publications to provide general information about gold ore and gold mineral, oxidative pre-treatment for gold refractory ore, thermodynamics of pyrite roasting, kinetics of pyrite roasting, and magnetic theory. The next step is to discuss about factors which can affect pyrite roasting and magnetic properties of the product calcine. Then, a comprehensive discussion is provided in relation to magnetizing roasting mechanism as pre-treatment method for refractory gold ore is discussed. The critical review indicates that various roasting parameter can affect type of iron sulfide/oxide phase and magnetic properties of calcine. FactSage simulation results show that magnetite phase could form by performing roasting with excess CO2 addition at 300 grams per grams of pyrite, or by performing roasting with controlled/limited air addition at 2 grams per grams of pyrite. From previous lab-scale experimental results, the optimal condition for magnetizing roasting have been found to be roasting at 750-950ºC in CO2 atmosphere. This calcine has high porosity which facilitates a good contact between leaching medium and gold mineral and has strong magnetic properties to separate gold-bearing mineral from its gangue, such as SiO2 and sulfide/sulphate minerals which cannot be oxidized in oxidative roasting.