The Pertraction Metal Refinery
Solvent extraction (SX) is one of the major separation and purification unit operations in hydrometallurgy. Its power lies in the many highly selective solvents that are commercially available. Mixer-settlers and extraction columns are the conventional process configurations. In SX, the aqueous pregnant leach solution (PLS) containing the metal solutes is contacted with an immiscible organic phase (solvent) containing a reagent that selectively removes one of the two or more metals from the PLS into the solvent. However, the dispersion of the one phase within the other often leads to technical and economical problems, including emulsification and third phase formation. An alternative technology that addresses these problems while offering substantially more contact area than mixer-settlers is the combination of SX and membrane contactors also referred to as pertraction (PX). In the extraction step, metals are selectively transferred from the aqueous to the organic phase via the membrane contactor without mixing of both phases. In scrubbing or stripping, the transfer is, again selectively, done in the reverse direction. The combination of these three steps provides a process for the beneficiation of metals (or other products) by ultra-purification.
The PX markets are in the recovery and purification of a range of metals: platinum group metals (PGM's), cobalt-nickel-copper, zinc, lithium, zirconium-hafnium, vanadium and rare earth elements(REE's). Also in the food industry, for example, the purification of phosphoric acid and acetic acid. These industries are mainly widely located, inclusive of in South Africa, DRC, Namibia, Zambia, China, Australia, USA, Canada, Europe, Russia and Chili. The exact sizes of these industries in terms of volume and economic value are difficult to estimate. A more recent application is in the recovery and recycling of valuable metals from electronic waste (E-waste)
The PX metal refinery will be a cost-effective new way to add value to South Africa’s many mineral resources. Although the focus will in the first instance be on mineral processing, spin-offs are to be expected in the environmental, (petro)chemical, pharmaceutical, food and beauty & health sectors. The applied science in PX focusses on mass transfer via the porous membrane and transport phenomena at both sides of the contactor and how to translate this to an efficient design of the PX module. PX technology has a number of innovative advantages over mixer-settlers and SX coulombs, including process flexibility, design, intensification, economy and reliability, as well as improved product quality control, safety and environmental advantages.
Solvent Extraction (SX) is one of the major separation and purification operations in hydrometallurgy. Its power lies in the many highly selective solvents that are commercially available. Mixer-settlers and extraction columns are the conventional process configurations. More recently pertraction technology using a liquid-liquid contractor has been introduced laboratory scale.
PX technology is SX using membrane contactors without mixing both phases. For example, during the extraction step, metals are selectively transferred from the aqueous to the organic phase via the membrane contactor without mixing of both phases. In scrubbing or stripping, the transfer is again selectively done in the reverse direction. The combination of these three steps provides an intensified process for the beneficiation of metals (or other products).
Pertraction (PX) is a combined process of solvent extraction (SX) and membrane technology. SX is one of the major separation and purification unit operations in hydrometallurgy due to the many highly selective solvents that are commercially available. For SX mixer-settlers and extraction columns are the conventional process configurations. More recently, PX technology has been introduced at laboratory scale.
Dolf Bruinsma - PhD at the University of Amsterdam (NL, 1987), was staff member of the Laboratory of Process Equipment of TU Delft (NL, 1987-2000), research director at North-West University (RSA, 2001-2007), ChemEng professor at North-West University (RSA, 2001-2008), program manager energy efficiency at the Energy research Centre of the Netherlands (NL, 2008-2012), program coordinator separation technology at the Institute for Sustainable Process Technology (NL, 2009-2012). Currently, he is Director and owner of Bruinsma solutions (RSA, 2013), Executive Consultant at the Technology Transfer Office of North-West University (RSA, 2014) and CTO of PX Technologies (RSA, 2017). His expertise is in separation equipment and separation processes for applications in hydrometallurgy, bioprocessing, distillation, melt crystallization, precipitation, drying and filtration. He published ± 100 papers in refereed international journals and ± 50 usually confidential industrial reports. He was a mentor of about 80 postgraduate students in NL and RSA.
Peter Cole - a world-renowned hydrometallurgist with 35 years’ experience in the processing of base and precious metals and uranium. He has specialist knowledge of solvent extraction (SX) and ion exchange technologies and is expert in separation processes and their integration with up and down-stream process steps. He is experienced in R&D, engineering design and costing, project evaluation and process optimisation. As Group Leader of the Separation Processes Group at Mintek, Peter managed a portfolio of hydrometallurgy research programmes for some of the major global mining houses. His partnership responsibilities with Matomo Projects included project management from process design to installation of SX plants for copper (Dukwe Copper Project) and cobalt and nickel (Tati Nickel Demo Project) separations. He gained extensive operations experience on the commissioning teams of various SX projects around the world and optimization of copper SX operations while Technical Manager at Cytec Industries.
Jaco du Toit - more than 15 years’ collective metallurgical research, development and engineering experience, focused primarily on hydrometallurgy and process engineering, but also includes pyrometallurgy and minerals processing. This includes 6 years Engineering Design exposure focusing on Sulphuric Acid, Gold, Uranium and Base Metal processing plant design, and technical mineral processing, hydrometallurgical plant audits & development and review of alternative energy