Research Focus

The current and standard ways of minerals separation recovery has been largely performed by the traditional reagents based on past discoveries, and our future prosperity will depend to a large extent on the fruits of contemporary research into novel and green reagents for a wide range of minerals with efficient flotation performance.

Research within the MMP Group is carried out in close collaboration with leading national and international experimental and theoretical groups in the field. Below are the three main group of minerals of our research activities.

Overview

Practically reactions in nature that involve minerals are surface or interface reactions. Whether it is crystal growth, adsorption reactions, mineral extraction and dissolution, or redox reactions, the actual reactions always occur at mineral surfaces. To understand and influence these processes, it is desirable to obtain a detailed insight into the surface and interface interactions at the molecular level. Molecular simulations provide mechanistic insights into the adsorption process and accurately predict the structures and properties of adsorption complexes of reagents onto mineral surfaces, which are critical for quantifying the adsorption.

Minerals are essential components in many of today’s rapidly growing demand for precious metals and critical minerals for energy technologies. Froth flotation is the most versatile physicochemical process in mineral processing, extensively used to concentrate a wide range of minerals. This process involves the adsorption of both organic and inorganic reagents at the mineral-water interface, selectively rendering the target mineral(s) hydrophobic and thereby recovering them in the froth phase. Collectors, which contain a polar group and a non-polar aliphatic chain, can be adapted in terms of chain length, unsaturation, and ramification, as well as functionalized polar groups. Depressants are essential in rendering the gangue minerals hydrophilic resulting in their suppressionn and reporting to the tailings. Moreover, all these reagents can be combined to improve flotation performance (selectivity or target mineral recovery). All these optimizations are challenging to investigate using purely experimental methods, and molecular modeling is a powerful tool for gaining a detailed, atomic-level understanding of the adsorption mechanisms of flotation reagents at mineral-water interfaces. The research focus aims to develop robust theoretical models and employ atomistic simulations (DFT, AIMD and MD simulations) to describe the mineral-water interface and the adsorption mechanisms of reagents molecules at finite temperatures in the froth flotation process. We are particularly interested in developing a theoretical framework to gain a deeper fundamental understanding of the structure-property relationship and the underlying adsorption mechanisms of green flotation reagents. The derived atomic-level insights are expected to motivate rational design and selection of future reagents molecules for enhanced recovery of precious and critical energy minerals.

1. Base Metal Sulphides Minerals: Surface Interactions and Flotation

Base metal sulphides (BMSs) are the most common minerals in the Bushveld complex of South Africa. They are the major host of the platinum group minerals, in particular pentlandite which host large quantities of platinum group elements (PGEs). There are number of well known BMSs along the pentlandite mineral such as pyrite, chalcopyrite, galena and sphalerite to name a few. These are commonly found in association with silicates minerals that are the most common gangue minerals. BMSs such as pyrite are considered as gangue mineral and is usually depressed in the flotation process. Understanding of the reactivity of these minerals, in particular from computational simulations provide significant information for their recovery and depression. In particular understanding pentlandite unlocks the recovery of PGMs. In the current age metals such as nickel, zinc and copper are critical for utilisation in energy industry such as batteries which are currently driving the electric vehicle growing demand. This research theme employs cutting-edge materials theory and simulation to predict novel reagents molecules interactions with BMSs mineral surfaces and to validate from microflotation experiment to improve their recoveries. Recurring themes here include understanding the formation of these minerals to establish new knowledge on the mineralogy.

2. Platinum Group Minerals (PGMs): Surface Interactions and Flotation

Platinum group minerals (PGMs) are largely found in large quantities (around 70%) in the Bushveld complex of South Africa. Other quantities are found in the Stillwater complex in USA, the Great Dyke in Zimbabwe and the Noril’sk-Talnakh complex in Russia. They are the major host of the platinum group elements (PGEs). These are usually found in association with base metal sulphide (BMSs) such pentlandite, pyrite, chalcopyrite, galena and sphalerite and other silicates minerals that are the most common gangue minerals. Understanding of the reactivity of these minerals, in particular from computational simulations provide significant information for their recovery separation from the gangue. In particular understanding pentlandite unlocks the recovery of PGMs. There is a current drive for beneficiation of the precious metals such platinum for hydrogen fuel energy as a catalyst. This research theme employs cutting-edge materials theory and simulation to predict novel reagents molecules interactions with PGMs mineral surfaces and to validate from microflotation and microcalorimetry experiments to improve their recoveries. Recurring themes here include understanding the formation of these minerals to establish new knowledge on the mineralogy.

3. Critical Energy Minerals (CEMs): Surface Interactions and Flotation

Critical energy minerals (CEMs) are the current significant minerals that are driving the high demand for energy storage and electric vehicles. The most common critical elements are lithium, manganese, nickel, cobalt and rare earths. The minerals of interest are spodumene, petalite, graphene and pyrolusite. These are commonly found in association with silicates gangue minerals such as quartz, calcite and feldspar. Understanding of the reactivity of these minerals, in particular from computational simulations provides significant information for their recovery separation. This research theme employs cutting-edge materials theory and simulation to predict novel reagents molecules interactions with CEMs surfaces to improve their recoveries. Recurring themes here include understanding the formation of these minerals to establish new knowledge on the mineralogy.

Research Collaborations and Partnerships

The MMP Group is always very keen to collaborate with leading experimental and theoretical groups.

Theoretical Collaborators

Professor Phuti E. Ngoepe, University of Limpopo, SA
Professor Nelson Dzade, Pennsylvania State University, US

Experimental Collaborators

Professor Xingrong Zhang, Qingdao University of Science and Technology, CN
Professor Belinda McFadzean, University of Cape Town, SA
Dr. Chongjun Liu, BGRIMM Technology Group, CN

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