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23rd November 2023

Signature Series - Emeritus Professor Cyril O'Connor, Uni. of Cape Town (South Africa) 29 Nov 2023 'Review of important developments in flotation chemistry.... and challenges and opportunities for the future'

COEMinerals Signature Series Lecture Recording:


Review of important developments in flotation chemistry since the 1st International Mineral Processing Congress in 1952 and challenges and opportunities for the future

Presenter: Prof Cyril O’Connor

Emeritus Professor and Senior Research Scholar, Chemical Engineering 

University of Cape Town, South Africa


Since the 1st IMPC took place in London in 1952 there have been many significant developments in our understanding of flotation both in terms of chemical and physical factors influencing the process. Many of these developments have been captured in the Proceedings of the Congresses that have taken place since that first event as well as in numerous journal papers and special volumes dedicated to flotation. This paper highlights the contributions which many eminent researchers have made over the past 70 years towards extending our understanding of especially the effects of chemical factors on flotation. Although the focus is mainly on more fundamental aspects it is clear that much research has focused on attempting to understand many empirical observations made by operators. The paper begins with the early seminal relationship that was demonstrated between zeta potential, pH, contact angle, surface coverage and flotation recovery. Then developments in the areas of hemi-micelles, the hydrophobic force, the development of modern analytical techniques, the progressive understanding of the surface reactions between minerals often using electrochemical measurements, the developments of new collectors especially for sulphide and silicate mineral types and the ever-increasing appreciation of the critical role which frothers play in the flotation process. Finally challenges for the future are proposed including the supply of adequately trained mineral processors, the need for a closed water cycle on concentrators, the use of molecular modelling to design new environmentally compliant reagents, the use of AI and machine learning in modelling flotation behaviour and lastly the complexities associated with efficiently transferring new knowledge to operations.


Cyril O’Connor is a registered chemical engineer with a Ph.D. from the University of Cape Town and a Senior Doctorate (D.Eng.) in Metallurgical Engineering from Stellenbosch University. He is the immediate past Director of the Centre for Minerals Research and was the founder Director of the Centre for Catalysis Research, both of which are located in the Department of Chemical Engineering at the University of Cape Town. He was President of the International Mineral Processing Council (20062020), held the Anglo-American Platinum Chair in Minerals Processing (20082012), was Vice-President of the International Zeolite Association (19982004), was a member of the Executive of the Academy of Engineering of South Africa (20122019) and is CEO of the South African Minerals to Metals Research Institute. He has chaired numerous scientific panels and boards and has served from time to time on various international scientific committees and review panels, has chaired the Organizing Committees of a number of major international conferences and is presently the Chair of the International Advisory Panel for a major Australian research centre. He has published over 300 papers in international journals and international refereed conference proceedings, has supervised more than 80 PhD and MSc graduates and at his retirement was a National Research Foundation A rated researcher. Prior to his retirement at the end of 2009, he was Head of the Department of Chemical Engineering (8 years), Dean of the Faculty of Engineering & the Built Environment (10 years) and served as an Acting Deputy Vice-Chancellor in 20089. He is a Hon. Fellow and Fellow of the South African Institute of Mining and Metallurgy, a Fellow of, respectively, the Royal Society of South Africa, the University of Cape Town, the South African Academy of Engineering, the South African Institution of Chemical Engineering, IUPAC and is a founder member of the Academy of Science of South Africa. In 2017 he was elected as an International Member of the US National Academy of Engineering and in 2023 was awarded the Antoine M Gaudin Award by the US SME/AIME which is their highest award in the field of mineral and metallurgical processing.