The contributions of geometallurgy to the recovery of lithified heavy mineral resources at the Namakwa Sands mine, West Coast of South Africa

The Namakwa Sands heavy mineral deposit is located at Brand-se-Baai along the West Coast of South Africa and is a world class producer of premium quality zircon (ZrSiO4), ilmenite (FeTiO3) and rutile (TiO2) concentrates from mainly aeolian sands. Superimposed on the coastal clastic Cainozoic ore-bearing sequence is a calcium–magnesium-rich pseudo-stratigraphy locally referred to as cemented hard layers that effectively lithify the mineralised sands to various degrees of hardness, rendering it unsuitable for routine treatment by wet spirals. Namakwa Sands has recently completed an expansion programme, inclusive of a SAG mill and screen installation, which allows the processing of the cemented hard layers, the first ever in the mineral sands industry. Operationally, the SAG mill and screen are performing well in tandem and are helping to improve mineral resource utilisation to levels not previously possible. Contained zircon output has increased, but at the cost of marginally lower recoveries as predicted from pilot studies. This paper reports on the systematic geometallurgical approach to improve mineral resource utilisation by successfully processing lithified ore.

► The Namakwa Sands Ti–Zr mine contains lithified, cemented ore.
► A SAG mill and control screen were installed to accomplish comminution.
► Ore minerals are effectively liberated for subsequent recovery.
► Applied geometallurgy assisted the mill design, commissioning and optimisation.
► Mineral resource utilisation increased to levels not previously possible.