“Pyrometallurgy
is an essential
and beautiful part
of sustaining society.”

ABOUT

Company Profile

OUR STORY

Ex Mente is a process engineering consulting and systems company, focused on pyrometallurgy. We guide our clients by means of expert consulting and training services as well as the deployment of software systems to improve their operations. The company was founded in 2001 and is based in Pretoria, South Africa.

OUR BRAND

Our brand was developed
on the concept of mutualism.

Our logo illustrates the greater honeyguide, which exists in a mutually beneficial relationship with humans, where both parties guide each other to success. The honeyguide leads humans to beehives for honey and reciprocally, humans clear the hives of bees allowing the honeyguide to eat beeswax. This relationship of mutualism symbolises how we guide our clients to solutions which allow them to unlock maximum value from their resources.

OUR VISION

Our vision is to develop a thriving pyrometallurgical industry by unlocking value with our clients, through deeper insight into their materials, processes and equipment.  We strive to forge meaningful long-term partnerships with our clients.

OUR FOCUS

We are fascinated by pyrometallurgy and believe it has a key role to play in the advancement of society. We have developed a unique set of skills and tools to assist our clients in improving their pyrometallurgical operations.

OUR TEAM

OUR TEAM

DR Johan Zietsman

CEO

Researchgate Linkedin-in

Marius Schoeman

Chairman of the Board

Linkedin-in

Dr Willem van Niekerk

Non-executive Board Member

Linkedin-in

Dr Alfred Bogaers

PRINCIPAL MECHANICAL ENGINEER

Researchgate

Megan Boshoff

Intern Business Administration

Linkedin-in

Roger Bosman

Research Engineer

Researchgate Linkedin-in

Rita de Villiers

Administrative Officer

Linkedin-in

Stefan Koning

Computational Chemist

Researchgate Linkedin-in

Tumelo Makgoale

PROCESS ENGINEER

Researchgate Linkedin-in

Dr Callie Marais

Process Engineer

Researchgate Linkedin-in

Edna Monyepao

OFFICE ASSISTANT

Hanno Muire

Materials Engineer

Researchgate Linkedin-in

Dr Johan Nell

Strategic Research Advisor

Linkedin-in

Thys Nortjé

Digital Engineer

Linkedin-in

Myren Rajh

Mechanical Engineer in training

Linkedin-in

Albertus Richter

Digital Engineer

Researchgate Linkedin-in

Coetzee Richter

Project Manager

Linkedin-in

Dr Willem Roos

SENIOR MECHANICAL ENGINEER

Researchgate Linkedin-in

Dr Jaco Swanepoel

Senior Process Engineer

Researchgate Linkedin-in

Zartius Swart

Project Manager

Linkedin-in

Stefan van der Merwe

Digital Engineer

Researchgate Linkedin-in

Heine Weitz

MANAGING DIRECTOR - EX MENTE EUROPE

Researchgate Linkedin-in

Stefan Zaaiman

Research Scientist

Researchgate Linkedin-in

Dr Mengyi Zhu

Computational Engineer

Researchgate Linkedin-in

Marinda Zietsman

COO

Linkedin-in

PROCESS ENGINEERING TEAM

FROM LEFT TO RIGHT:
Dr Johan Zietsman, Tumelo Makgoale, Dr Callie Marais,
Dr Johan Nell, Dr Jaco Swanepoel, Heine Weitz

MULTIPHYSICS TEAM

FROM LEFT TO RIGHT:
Dr Johan Zietsman, Dr Alfred Bogaers, Roger Bosman,
Myren Rajh, Dr Willem Roos

Digital Team

FROM LEFT TO RIGHT:
Dr Johan Zietsman, Thys Nortjé, Albertus Richter,
Stefan van der Merwe

Materials Science Team

FROM LEFT TO RIGHT:
Dr Johan Zietsman, Stefan Koning, Hanno Muire,
Stefan Zaaiman, Dr Mengyi Zhu

OPERATIONS TEAM

FROM LEFT TO RIGHT:
Dr Johan Zietsman, Megan Boshoff, Rita de Villiers,
Edna Monyepao, Coetzee Richter, Zartius Swart,
Marinda Zietsman

EX MENTE EUROPE

FROM LEFT TO RIGHT:
Dr Johan Zietsman, Heine Weitz

DR Johan Zietsman

CEO

Johan is an experienced metallurgical engineer, skilled in pyrometallurgy, thermochemistry, computational modelling and consulting in a wide range of commodities such as iron and steel, high-titania slag, ferrochrome, ferromanganese and platinum group metals. Through his software engineering skills and experience, he contributes to system design and implementation solutions for clients.

Johan leads the Ex Mente team and supervises a number of postgraduate students at the University of Pretoria.

Marius Schoeman

Chairman of the Board

Marius is a qualified Chartered Accountant (SA) and Chartered Director CD(SA)® with more than 35 years’ experience across the Audit Profession, Oil & Gas, ICT and Financial Services sectors.

He has served in various senior level executive roles, among others, a Chief Audit Executive, Group Risk Officer, Ethics Officer as well as Group CFO of a JSE listed entity.
He is founder and CEO of Ujasiri Consulting and advises a number of corporate clients on governance, risk and compliance (GRC), assurance and contracted services as a Compliance Officer, Information Officer and Head of Legal and Business Support. With his wealth of experience, Marius is an invaluable member of the Ex Mente board.

Dr Willem van Niekerk

Non-executive Board Member

Willem is an experienced senior executive with nearly 40 years of experience in the minerals, mining and chemical industries. He holds a PhD from the University of Pretoria, a BCom from UNISA, an MBA from Henley Management College (UK) and has published/presented nearly 30 papers globally.

Willem’s skills range from innovative technological developments to leading chemical and mining operations globally. He has served on numerous boards and has extensive corporate governance experience, which he now offers to Ex Mente as a board member of the company. Aside from his involvement at Ex Mente, Willem is an independent consultant since retiring from Tronox (NYSE listed) in 2021.

Dr Alfred Bogaers

PRINCIPAL MECHANICAL ENGINEER

Alfred is a mechanical engineer specialising in computational mechanics and numerical methods. His focus is primarily on Multiphysics modelling of problems related to conjugate heat transfer and fluid-structure interactions. Throughout his career, he has received various awards including best PhD (Faculty of Engineering and the Built Environment, UCT), best Masters (Department of Mechanical and Aeronautical Engineering, UP), best paper awards at both local and international conferences as well as a number of emerging researcher awards.

Megan Boshoff

INTERN BUSINESS ADMINISTRATION

Megan is an Administrative Intern and is part of our daily operations, providing support across various functions. She is pursuing her BCom in Management Accounting.

Roger Bosman

Research Engineer

Roger completed his Master’s in Chemical Engineering and is now pursuing PhD studies in Metallurgical Engineering. While his Master’s focused on the digital control of hydroponic systems, he has pivoted towards the study of high-temperature, thermochemical systems for PhD. It is hoped that Roger’s research will help clients by lending greater insight into pyrometallurgical processes.

Rita de Villiers

Administrative Officer

Rita is dedicated to supporting the team and the organisation to function more effectively.
She is responsible for supplier relations and administration, organising conferences, and keeping the office running on a day-to-day basis.

Stefan Koning

Computational Chemist

Stefan holds a master’s degree in Computational Chemistry from the University of Pretoria. He has a multifunctional role within Ex Mente and forms part of the Material Science and Software Engineering groups.

Tumelo Makgoale

PROCESS ENGINEER

Tumelo is a metallurgical engineer, who recently completed his master’s degree in the field of Pyrometallurgy. He helps clients to improve their processes with tools such as thermochemistry and process models.

Dr Callie Marais

Process Engineer

Callie is a process engineer. He completed his PhD in Chemical Engineering at the North-West University, which focused on extrusion, pyrolysis, and gasification. Callie is part of the Process Engineering team who helps clients understand their thermochemical processes through advanced modelling. He is also constantly involved in identifying opportunities, strengthening relationships, and driving future growth as part of the business development function.

Edna Monyepao

OFFICE ASSISTANT

Edna is the Ex Mente team’s administration assistant. She is a friendly, helpful person and her main responsibility is to support and care for the team in any way possible.

Hanno Muire

Materials Engineer

Hanno is completing a master’s degree at the Department of Chemical Engineering at the University of Pretoria. He holds a Bachelor’s and an Honours degree in Chemical Engineering from the same institution. His role at Ex Mente is as a materials engineer, where he applies his knowledge and skills to research, model, and simulate material properties for pyrometallurgy processes.

Dr Johan Nell

Strategic Research Advisor

Johan has more than 40 years’ experience working in the metallurgical industry. He holds a PhD in geosciences from Northwestern University (Evanston, Illinois), a M.Sc. in geology from the University of Pretoria and has done post-doctoral research at the University of Bristol and at the Bayerisches Geoinstitut für experimentelle Geochemie und Geophysik (Bayreuth, Germany) with an Alexander von Humbold fellowship. He has published and presented more than 40 papers globally.

Johan’s university training in igneous and metamorphic petrology provided him with unique perspective on high-temperature metallurgical operations that he successfully applied to trouble-shooting of under-performing metallurgical operations, optimisation of slag composition, slag cooling, roasting, pre-reduction and refractory corrosion, working for a broad base of clients in the base metal and ferroalloy industries. Apart from technical studies he has also undertaken many technology- and due diligence-reviews. Johan joins the Process Engineering group at Ex Mente.

Thys Nortjé

Digital Engineer

Thys holds a Bachelor’s degree in Computer Engineering from the University of Pretoria. As a Software Engineer in the Digital Team at Ex Mente, he focuses on developing high-quality software solutions. Driven by a passion for well-designed and well-implemented systems, he contributes to building robust tools that support both the organization and its clients.

Myren Rajh

Mechanical Engineer in training

As a Mechanical Engineer, Myren is passionate about computational mechanics and programming, with a strong interest in solving complex physics problems through code development. He enjoys diving deep into challenging problems, exploring multiple solutions, and iterating toward the best outcome.

Albertus Richter

Digital Engineer

Albertus holds a Master’s degree in Electronic Engineering from the University of Pretoria, specialising in Control Systems, with a focus on advanced process control and optimisation. His career in the mineral processing industry began through his postgraduate research, which focused on advanced process control in this field. Albertus is part of the Digital Team at Ex Mente, where he contributes to developing software solutions to support the broader organisation and its clients.

Coetzee Richter

Project Manager

Coetzee Richter is a dedicated Project Manager and forms part of the operations team. He earned a Bachelor of Commerce degree in Human Resource Management from the University of Pretoria, providing a solid foundation for understanding team dynamics and individual potential.

Dr Willem Roos

SENIOR MECHANICAL ENGINEER

Willem is a mechanical engineer with a newfound interest in thermochemistry and its inclusion into multiphysics and process models.
He is part of the Multiphysics team at Ex Mente where he contributes to the solvers and models that are developed to investigate large, complex, high-temperature systems.
Through his PhD research at the University of Pretoria, he developed, implemented, and tested an acceleration algorithm that would allow a large number of multi-component, multi-phase, high-temperature thermochemical equilibrium calculations to be included into multiphysics and process models more efficiently.
This will allow our multiphysics and process models to provide additional insight into industrial processes and equipment.

Dr Jaco Swanepoel

SENIOR PROCESS ENGINEER

Jaco is a Chemical Engineer with twelve years of experience in projects that range from reactive metals handling, reactive metal powder production in molten salt slurry reactors, extractive metallurgy to microwave-assisted gas-solid materials processing.
Jaco contributed to three process patents and obtained a PhD degree in Chemical Engineering. Jaco also completed the KTP Management and Leadership Study Program at Ashorne Hill Management College, England.

Zartius Swart

Project Manager

Zartius is dedicated to supporting the team and ultimately to add more value to our clients. He is a member of the operations team at Ex Mente, with a dedicated focus on developing and enhancing business processes to improve our efficiency.

Stefan van der Merwe

Digital Engineer

Stefan’s greatest passion is to enable people. By combining his greatest passion with his love for technology, he finds joy in making computing infrastructure accessible to the non-technical, and developing software that uncomplicates tasks. As a software engineer with qualifications in electronic engineering and bioengineering, Stefan is responsible for software development, enabling the team and clients to advance through insight.

Heine Weitz

MANAGING DIRECTOR - EX MENTE EUROPE

As a metallurgical engineer by training, Heine has invested the majority of his career in the pyrometallurgical industry, serving in different roles in operations, design and consulting companies. He has had the privilege of working with numerous commodities across the globe including Africa, North America, Europe, the Middle East and Asia.

His professional interests include operational and process analysis, thermochemistry, computational modelling and process development and improvement.

Heine leads Ex Mente Europe as managing director. In this role he is responsible for growing the team in Europe and to ensure that we make a meaningful contribution in the region’s pyrometallurgical industry.

Stefan Zaaiman

Research Scientist

Stéfan is a computational chemist who recently completed his master’s degree in Theoretical Chemistry at the University of Pretoria and is currently busy with his PhD studies. Stéfan is part of the Materials Science team who assists the Process Engineering and Multiphysics teams with material properties.

Dr Mengyi Zhu

Computational Engineer

Mengyi is a computational scientist at Ex Mente, specialising in slag science and engineering. He received his Bachelor’s degree in Metallurgical Engineering from the University of Science and Technology Beijing, his master’s from RWTH Aachen University, and his Ph.D. from the Norwegian University of Science and Technology. Driven by a passion for discovery, he continues his journey at Ex Mente engaged in advancing the continuous growth of the pyrometallurgy community.

Marinda Zietsman

COO

Marinda has been with Ex Mente for the past 20 years, supporting operations management to create an environment in which the Ex Mente team can do great things. Her main areas of responsibility are finance, human resources, legal, business management and software sales.