Impacts of Pulp Chemistry on Gold Particle Surface Chemistry and Floatability

Eric Aminarety Agorhom, Samuel Nkrum Asare-Asher, Yvonne Owus-Ansah


Pulp chemical changes and surface chemistry play a crucial role in collector adsorption onto gold and copper minerals for an improved flotation. The expected recovery of gold is not always the same as copper minerals recovery due to the differences in mineralogy and surface chemistry. The current study investigates the surface behaviour of gold particles in a typical porphyry copper-gold ore flotation pulp. Due to the trace nature of gold in the ore, the surface behaviour was stimulated with a pure gold substrate. The surface chemistry changes before and after exposing the gold substrate to the pulp conditioned with air, XD5002, MIBC, and DETA were assessed using XPS and contact angle measurements. The substrate contained 92.3% Au and 7.7% O. Exposure to the pulp showed a drastic decrease in gold to 18% with an increase in oxygen to 42.3% and appearance of 3% S, 3.2% Fe, 2.1% Cu, 23.4% C, 6.6% Si and 1.2% Zn. The presence of these hydrophilic loadings decreased the contact angle of the pure gold substrate from 84° to 47° and subsequently increased to 59° and 74° after re-exposing the contaminated gold surface to EDTA extraction and XD5002 collector solution, respectively. The study showed that the observed contamination for pure Au substrates exposed to the pulp may be more extensive on “in-ore” surface as they would be expected to contain more reactive sites and might be a contributing factor to Au losses encountered during copper-gold flotation, especially at the finer grind size.


Pulp Chemistry, Contact Angle, DETA, Collector, XPS

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