Fika Rofiek Mufakhir, Virga Bagus Prayoga, Soesaptri Oediyani, Widi Astuti, Slamet Sumardi, Sudibyo, La Ode Arham
One of the Tanggamus gold ore types in Lampung Province is a refractory sulfide dominated by quartz (SiO2) and pyrite (FeS2) minerals with a 10.58% sulfur (S) content. The gold recovery will be less efficient without pretreatment and if only using the conventional method (direct cyanide leaching). An alternative method is introduced by combining physical and chemical routes to gain a preferable gold dissolution rate. This study aimed to determine the effect of pH, temperature, and percent solids on the weight of dissolved gold from various types of leaching feed. First, the gold ore was crushed and ground until the particle size was under 74 microns. Then, the two-stage pretreatment was introduced: the roasting process was conducted to form hematite (F2O3) mineral, which has high magnetic properties with a 1.301% sulfur trace-followed by low wet magnetic separation to separate ore with magnetic and non-magnetic minerals. Next, the gold ore with pretreatment was leached using thiourea solution and iron (III) as an oxidation agent in a 1000 ml reactor, completed with a hotplate-magnetic stirrer and condensing system. The highest gold dissolution was obtained from a magnetic concentrate at pH 1, the temperature of 50°C, thiourea concentration of 0.013 M, iron (III) concentration of 0.0195 M, a solid percentage of 20%, and stirring speed of 600 rpm for 10 hours. This study concluded that gold is more easily dissolved if gold is present in hematite matrices rather than quartz matrices. At low pH, thiourea could be used as an alternative to gold dissolution reagents. © 2024 Author(s).
Research Center for Mining Technology, National Research and Innovation Agency, Jl. Ir. Sutami KM. 15 Tanjung Bintang, South Lampung, 35361, Indonesia; Metallurgical Engineering Department, Sultan Ageng Tirtayasa University, Jl. Sudirman Km 3, Banten, Cilegon, 42435, Indonesia; Mining Engineering Department, Institut Teknologi Sumatera (ITERA), South Lampung, 35365, Indonesia