AN INVESTIGATION OF COPPER RECOVERY FROM A SULPHIDE OXIDE ORE WITH A MIXED COLLECTOR SYSTEM by Morgan Sarah Davidson A thesis submitted to the Department of Mining Engineering in conformity with the requirements for the degree of Master of Science in Engineering Queen’s University Kingston, Ontario, Canada (August , 2009) Copyright ©Morgan Sarah Davidson, 2009 For Daddy. ii Abstract Current copper deposits contain significant amounts of secondary non-sulphide minerals and newly discovered deposits are increasingly complex. As a result, research into the improvement of sulphide-oxide copper ores processing through the use of mixed collector systems has surged. The flotation of a natural porphyry copper ore with bornite and malachite was investigated via fundamental work with pure minerals and a bench-scale testing regime. The processing of the test ore was problematic due to a mineral assemblage that caused prevalent slime generation. Fundamental adsorption, micro-flotation and Eh-pH tests were conducted on pure minerals to investigate mineral-collector behaviours. PAX and hydroxamate form multiple collector layers on malachite and bornite, with malachite and hydroxamate exhibiting the highest adsorption density. The effective pH range of the collectors was pH 8-10 where the collector species, according to equilibrium species distribution diagrams, were Cu(HXM)2 (aq) and CuEX (s) for hydroxamate and xanthate respectively. A Box-Behnken response surface design was used to determine collector dosages that provide an optimum flotation response for the natural ore. The collectors were: potassium amyl xanthate (PAX), Cytec Promoter 6494 hydroxamate and DETA. The copper recovery, malachite recovery, minor copper recovery and copper grade responses were optimized using JMP statistical software. Indicators of model inadequacies were noted but since the models predicted sensible solutions, inaccurate test ratios and un-modeled effects were hypothesized to be the source of the inadequacies. The model predicted 98 % copper recovery using 202.7g/t PAX, 674.99 g/t hydroxamate and 61.9 g/t DETA. The copper grade model predicted an the overall copper grade of 19% using with 0 g/t PAX, 167 g/t hydroxamate and 101 g/t DETA . iii Acknowledgements I would like to thank my supervisor, Dr. Sadan Kelebek, for his help throughout my time as a graduate student. Both as my professor and my supervisor, his knowledge, expertise and hours spent during this study were greatly appreciated. Thank you to Coban Resources for generously providing the test ore used in this thesis. I would like to say a big thank you to Maritza Bailey. She allowed me to draw on her experience to develop solutions to problems both in and out of the laboratory. Tina, Kate and Wanda in the office also deserve a special thank you. Their guidance and gossip were critical to keeping a good attitude while working through the stress of a tight deadline. I am grateful to Peter Auchincloss and Ayman. Without them, this thesis would have remained in softcopy format. My friends Aynsley, Allison, Jesse, Sarah, Lauren and Adrienne supported me through all parts of my undergraduate and graduate education. Alisa, Natalie, Tom, Mallory, Bryce and everyone else at Clark Hall Pub were a source of professional and non-professional direction. Ryan, Mark, Mike, Tina, Kristen, Erin and many others that have been here through my post graduate work were fellow commiserates, and celebrators of the joys and struggles of being a Master’s student. I could count on all these friends whenever I needed them, for this, I offer them a great many thanks and a debt of gratitude. I must thank my Mother, and acknowledge the direction she has given me from the beginning until now. She has a unique ability to put things into perspective; though, it can be as frustrating as it is fulfilling. Finally, thank you Mikhail. For everything else. iv Table of Contents Abstract ........................................................................................................................................... iii Acknowledgements ......................................................................................................................... iv List of Figures ................................................................................................................................ vii List of Tables ................................................................................................................................. xii Chapter 1 Introduction ..................................................................................................................... 1 Chapter 2 Literature Review ............................................................................................................ 6 2.1 Geology ............................................................................................................................ 9 2.2 Sulphidization ................................................................................................................ 12 2.2.1 Kinetics .................................................................................................................. 16 2.2.2 pH ........................................................................................................................... 17 2.2.3 Dosage.................................................................................................................... 19 2.2.4 Oxidization Reactions ............................................................................................ 20 2.3 Chelating Agents ............................................................................................................ 21 2.3.1 pH ........................................................................................................................... 25 2.3.2 Substituents ............................................................................................................ 26 2.3.3 Octyl Hydoxamate ................................................................................................. 27 2.4 Summary ........................................................................................................................ 33 Chapter 3 Materials and Methods .................................................................................................. 34 3.1 Adsorption...................................................................................................................... 34 3.2 Micro-flotation and Eh-pH............................................................................................. 36 3.3 Bench Scale Flotation .................................................................................................... 38 4.3.1 Exploratory Work .................................................................................................. 42 4.3.2 Preliminary Testing ................................................................................................ 42 4.3.3 Box-Behnken Design ............................................................................................. 43 3.3.4 N-phenylbenzohydroxamic acid ............................................................................ 47 Chapter 4 Results and Analysis ..................................................................................................... 49 4.1 Adsorption...................................................................................................................... 49 4.1.1 Malachite-PAX ...................................................................................................... 49 4.1.2 Malachite-Hydroxamate......................................................................................... 52 4.1.3 Bornite-PAX .......................................................................................................... 54 v 4.1.4 Bornite-Hydroxamate ............................................................................................ 56 4.2 Micro-flotation and Eh-pH............................................................................................. 58 4.2.1 PAX Micro-flotation .............................................................................................. 59 4.2.2 Hydroxamate Micro-flotation ................................................................................ 61 4.2.3 N-benzoyl Micro-flotation ..................................................................................... 62 4.2.4 Bornite Micro-flotation .......................................................................................... 64 4.2.5 Eh-pH ..................................................................................................................... 65 4.3 Bench Scale Flotation .................................................................................................... 71 4.3.1 Exploratory Work .................................................................................................. 75 4.3.2 Preliminary Investigation ....................................................................................... 76 4.3.3 Box-Behnken ......................................................................................................... 82 4.3.3.1 Copper Recovery .................................................................................................... 84 4.3.3.2 Malachite Recovery................................................................................................ 96 4.3.3.3 Minor Copper ......................................................................................................