Mineralogical characteristic and environment-friendly leaching tests for a lateritic gold ore

A systematic process mineralogy study and non-cyanide leaching tests were conducted on a lateritic gold ore. Process mineralogy analysis shows that the iron content in the ore reaches 42.60%, with a gold grade of 21.20 g/t. Gold occurs mainly as free and semi-exposed native gold (76.46%) and limonite-encapsulated gold (23.18%). The disseminated grain size of gold is fine. Gold is predominantly encapsulated by limonite and associated with pyrite, with only a small portion hosted in pyrite. Although the ore contains a high proportion of free and semi exposed gold, it exhibits poor leachability under conventional leaching conditions, as the fine gold particles are embedded and encapsulated within limonite. In consideration of the ore properties and green environmental protection requirements, a clean gold extraction process—fine grinding–ethylenediaminetetraacetic acid (EDTA) pretreatment leaching–environmentally friendly leaching agent Jinchan (JC) leaching–activated carbon adsorption—was developed. Through system optimization, the optimal process parameters were determined: grinding fineness of 85% at −0.074 mm, 0.25 g/L EDTA pretreatment for 12 h, JC leaching agent dosage of 5 g/L, 2.5 g/L CaO to adjust the pH to 12, and leaching time of 36 h. Under these conditions, the gold leaching rate increased to 97.17%, and the gold grade of the tailings decreased to 0.60 g/t. This study provides a reliable technical scheme and theoretical foundation for the efficient and environmentally friendly leaching of lateritic refractory gold deposits, as well as the green and economic development of similar mineral resources.