Development and implementation of a gravity-cyanidation technology for processing of highly preg-robbing gold ore with the subsequent transfer to a gravity-flotation-cyanidation flowsheet

This paper is devoted to development and implementation of a gravity + cyanidation technology for processing of highly preg-robbing gold ore from one of the Russian deposit with the subsequent transition to gravity + flotation + cyanidation technology. The ore contains 0.4 % of sulfide sulfur and 0.4 % of organic carbon. The main component of economical interest is gold 0.9-1.2 g/t. There is 81-87 % of cyanidable gold in ore according to a diagnostic leaching results. However, gold recovery decreases to54-61 % under plant conditions due to the extremely high ore preg-robbing activity. Since 2011, Irgiredmethas conducted laboratory studies of more than 50 laboratory ore samples. It was shown that gravity is efficient method of gold concentration with generation of non-refractory gravity concentrates with low pregrobbing. For 6 bulk samples (from 5 to 90 tons mass), a extensive R&D program was performed, including semi-industrial and pilot tests for several process flowshit options: direct cyanidation, gravity + cyanidation scheme with separate cyanidation of gravity concentrate and gravity tailings, and gravity-flotation-cyanidation with cyanidation of concentrates and high-temperature treatment of cyanidation tailings. The gravity-cyanidation scheme with a concentrate mass yield of 1.2 % provided an increase in total gold recovery by an average of 9 % compared to the direct cyanidation technology (recovery 63-69 %. The gravity-flotation-cyanidation scheme provided an increase of gold recovery up to 77.2-77.4 %. In 2023-2024, Irgiredmet developed technological regulations for the gravity-cyanidation flowsheet and a project design for the modernization of the mill. The introduced gravity-cyanidation flowsheet is a “springboard” for a more in-depth modernization of the plant with its transfer to the gravity-flotation-cyanidation flowsheet.