Comminution environment and gold particle morphology: Effects on gravity concentration

► Different comminution machines are used to prepare gold ores for gravity separation. ► The comminution environment influences the shape of the gold particle liberated. ► Different equipment produced various shapes of gold particles. ► Subsequent gravity separation of gold was affected by the morphology. In many laboratories and processing plants, different comminution equipment are used in preparing gold ores for gravity concentration. For malleable metals such as gold, particle shape changes in response to the forces applied during comminution, and these shapes can influence gravity concentration. In this study, the morphology of gold particles milled in different equipment was investigated. The disc and hammer mills generated cigar-shaped and globular particles respectively. The vibratory pulveriser created flaky particles while the ball mill formed a mix of flaky, folded and irregularly shaped particles. Gravity concentration produced enrichment ratios of 28.3, 24.0, 23.6 and 21.7 for the hammer mill, disc mill, ball mill and vibratory pulveriser respectively. The results show that the comminution equipment utilized should be taken into consideration in decisions regarding gravity gold recovery.