Kimberlite weathering : effects of organic reagents

Abstract

Kimberlite material is one of the primary sources of diamonds. Accelerated weathering that leads to a physical breakdown of the material over a short period of time has possible benefits in diamond processing such as reduction in the energy consumption when used as a pre-comminution stage. This study investigated accelerated weathering by utilising organic reagents; acetic acid, ethanol, formamide, n-hexane, oxalic acid, and urea, in comparison to the use of Cu2+ solution that was previously shown to be very effective in weathering kimberlite. Oxalic acid was the organic agent that showed promising weathering capabilities. However, the use of organic solutions was not as efficient as with Cu2+ solutions. Results showed that 67% of the particles passed 12 mm screen size in Cu2+ weathering compared to 48% in oxalic acid. It was also found that time of exposure had a small effect on weathering. Increasing the organic chemical concentration twofold, from 0.025 M to 0.5 M, improved weathering by 20% points. Different weathering mechanisms were observed at different solution concentration between oxalic acid (1st to 2nd order) and Cu2+ (2nd to 3rd order).