Geochemical Modelling Workshop – Using PHREEQC for laboratory and industrial applications.

Presenters:  Julien Declercq, Mike Herrell and Rob Bowell, SRK Consulting Limited

This two-day workshop will provide an overview of geochemical modelling and the use USGS geochemical / thermodynamic modelling code PHREEQC (PH, REdox, EQuilibrium, Code). PHREEQC is a free, well-supported software code and one of the most widely used codes in academia and the mining industry for thermodynamic modelling applications.   

During the two-day workshop, we will present the different geochemical modelling steps, from the development of a conceptual model and formalization of a modelling scenario to geochemical calculations using PHREEQC. We will also present exercises drawn from the presenters’ experiences, both in a laboratory setting and applied industrial setting.

The workshop will take place in four sessions split over the two days.

The first day will include an introductory session to PHREEQC covering the essential concepts of geochemical modelling, conceptualisation of model problems, an overview of the thermodynamics that govern PHREEQC and thermodynamic database definitions. We will explore issues with available PHREEQC thermodynamic databases and possible ways to overcome these. We will also provide the basic skills needed to use PHREEQC, including the definition of inputs and outputs, solid and aqueous solutions, and the reactions and equilibrium calculations. As the day progresses, we will introduce more advanced notions of kinetic reactions through a series of examples using experimental data.

The second day will provide a more in-depth look at the possibilities offered by PHREEQC in terms of predictive calculations and interpretation of the results relating to transport, exchange, isotope exchanges and sorption calculations. Based on our experience in mining, water, energy and chemical industries related applications of numerical predictive calculations, we will demonstrate how to use sorption experiments to define attenuation equations and sorption blocks. Furthermore, we will introduce exchange calculations and their application to water treatment and finally, we will bring all the elements seen in the workshop together in transport simulations.

The workshop will finish with a general discussion.

Intended Audience:

This course is intended for students, researchers, and professionals planning to use or expand their knowledge of PHREEQC for modelling and predicting results of geochemical operations, from simulation of laboratory experiments to natural settings (such as groundwater interaction with bedrock, simulating field data and predicting water quality).

Attendees are encouraged to bring with them their own examples of natural or laboratory systems that they wish to model for discussion with the session tutors.

Presenters’ biography

Julien Declercq, FGS, MSc. (Geology), PhD (Geochemistry)

Julien is a Senior Consultant with over ten years’ experience in environmental geochemistry, applied primarily to environmental mine impact assessment. Julien’s PhD and subsequent postdoctoral research focused on using PHREEQC to define the reactivity of minerals (mainly forsterite) in the conditions necessary for CO2 storage in aquifers, predict the conditions of the experiments and to model the experimental results. His consulting expertise includes characterisation of mine wastes for assessment of Acid Rock Drainage and Metal Leaching (ARDML), contaminate transport models and water quality prediction, field and laboratory based analytical geochemistry, laboratory experiments, numerical geochemical modelling including thermodynamic, kinetic and reactive transport, mineralogy and geochemical data analysis. Julien has also undertaken a revision of the MinteqA2 database and build a mineral dissolution kinetics database for PHREEQC.

Eur. Geol. R. J. Bowell PhD, C.Chem MRSC, C.Geol FGS FIMMM  P.Geo

Rob is a Geochemist, Professor and Corporate Consultant, with 34 years’ experience and a background in applied geology in tropical and deeply weathered terrain. His mining consulting experience is extensive in the fields of due diligence, financial and technical audits, including process chemistry, environmental geochemistry, environmental engineering and mineralogy all over the globe. With 278 publications in the field of mineralogy, process chemistry, and applied geochemistry, ARD, contaminated land and water treatment Rob is an internationally recognised expert in the application of geochemistry to the challenges of the mining industry.  He is currently also an adjunct professor at Department of Earth Sciences, Queen’s University, Kingston, Ontario, Canada.

Michael Herrell, MSc, P.Geo

Michael Herrell is a Principal Consultant (Geochemistry) based in SRK’s Vancouver office. He has 20 years of experience working on geochemical investigations. His main area of focus is conducting geochemical characterization studies for proposed, operating and closed mine site facilities.  These studies involve assessing the acid rock drainage (ARD) potential and metal mobility from mine materials (i.e. waste rock, tailings and marginal ore, etc.) and evaluating the results of the geochemical characterization in the context of mine water management strategies to predict site effluent and receiving environment water quality. The latter requires development of predictive models, which Michael often develops in PHREEQC. He predominantly uses PHREEQC to perform mixing calculations, speciation, mineral precipitation and sorption reactions to evaluate mineralogical controls on mine site facility drainage water quality or in pit lake water quality at closure. Michael has also used PHREEQC to inform treatment design studies, including an evaluation of influent sources to prevent scaling in a treatment system and lime treatment of acidic water ponds.

Materials Provided

Each participant will receive: (1) paper and electronic versions of the hand-outs used for the lecture part of the workshop; and (2) an electronic copy of the model inputs used during the course of the workshop.

Materials Required

Laptop equipped with a version of Microsoft windows with PHREEQC interactive (current build: v3.7.3-15968) downloaded and installed. The latest version can be found at:

Useful links:

SRK Consulting (UK) Ltd

PHREEQC manual, available here:

PHREEQC abstract:

Tony Appelo’s web page for introductory exercises:

PHEEQC frequently asked questions:

Contact:+44 (0) 2920 348 150 SRK Consulting (UK) Ltd; 5th Floor, Churchill House 17 Churchill Way; Cardiff, CF10 2HH United Kingdom