The Depressing Effect of Clay Minerals on the Floatability of Chalcopyrite

ABSTRACT

In this work, the depressing effect of clay minerals on the floatability of chalcopyrite using PAX as collector was assessed through induction time and settling-turbidity measurements. The data obtained using these two techniques were correlated with the results of micro-flotation tests carried out to study the effect of kaolinite and smectite particles on the floatability of chalcopyrite at pH 9 and 10. The results indicate that these techniques can be confidently used to examine interactions between clay minerals and chalcopyrite, and their possible consequences on the flotation process. In particular, the use of settling-turbidity measurements to evaluate slime coating seems to be a useful technique that could be applied to study heterocoagulation in other mineral systems. It was found that the depressing effect of clay minerals was stronger at pH 10, which was correlated to a possible effect of Ca²⁺ from lime on the process of coagulation between clay minerals and chalcopyrite. Coating of bubbles with clays was detected in this work by visual observations and it is proposed as a mechanism that might explain the depressing effect of clays on the floatability of chalcopyrite. Further research is needed to propose a mechanism that explains this phenomenon.

KEYWORDS:

• Chalcopyrite
• clay minerals
• flotation
• induction time
• slime coating

Acknowledgments

The authors want to thank Dr. Janusz Laskowski for his valuable comments that allowed them to improve this manuscript. The authors also want to thank Mr. Cristian Melipichun and Mr. Roberto Vazquez for their valuable contributions during the experimental program.

Funding

Support from the National Fund for Scientific and Technological Development (FONDECYT) of Chile under the project initiation into research no. 11140184, Centro CRHIAM Proyecto Conicyt Fondap no. 15130015, and Universidad de Concepcion under Project VRID no. 214.095.089-1.0 is gratefully acknowledged. Lina Uribe wants to acknowledge the support from Conicyt Scholarship for Doctoral Studies in Chile 2015 (Folio postulación 21150151).