Intensification of gravity concentration of refractory gold-bearing ores

As high-grade gold-bearing ore reserves rapidly become depleted, there is a growing shift towards processing lower-grade refractory ores. These ores contain gold that is finely dispersed, making it more challenging to extract. Gravity beneficiation is a common initial processing method used for these ores. However, due to the extremely small size of the gold particles, significant amounts of gold are lost during this process. This study explores methods to improve gravity beneficiation of refractory gold-bearing ores from the Vasilkovskoye deposit. Physicochemical and particle size distribution analyses have shown that gold particles in the ore samples are very small, ranging from 0.01 mm to 0.074 mm in size. Most of these particles are either dust-like or flaky and are smaller than 0.074 mm. In order to optimize the recovery of fine particles of heavy native gold and gold-bearing minerals, the design of the centrifugal hydroconcentrator was refined and a closed-cycle multi-stage concentration process was developed, which improved the recovery of gold from the Vasilkovskoye deposit ore to 56.7 %. Comparative concentration experiments for various gold-bearing ores, including tailings and waste from several processing plants, have demonstrated that the newly developed gravity beneficiation technology can improve gold concentration efficiency by a factor of 2.38. This advanced technology enables the almost complete recovery of gold particles up to 0.074 mm in size and improves the recovery of very fine, dust-like, plate-like, and flaky gold particles by approximately 15–20 %. The resulting concentrate grades meet the current requirements of gold plants.