Corrensstr. 24 48149 Münster, Germany
Tel.: +49 251 83-33464
Fax: +49 251 83-38397


The DELTA-MIN Research Training Project

Project Overview

The scientific objective of Δ-MIN is to significantly advance the understanding of fluid induced mineral transformation mechanisms, by assembling a group of European industrial and academic experts working in different environments but in related fields. The project will be the first time such a range of diverse phenomena will be explored from a unified point of view. The project will combine observations from natural rocks, experimental studies of mineral-fluid interaction and fundamental theory to understand dissolution, precipitation and mass transport. Observation will range from the mega- to the nano-scale: from estimating the extent of metasomatism in rocks, to high resolution transmission electron microscopy of reaction interfaces.

The project will make significant breakthroughs in both the fundamental mechanism of fluid-mediated mineral transformations and their application to industrial problems. The newly-defined concept of interface-coupled dissolution-reprecipitation will be used to explain how reactive fluids transform initially impermeable minerals. The same formalism will be applied to the individual projects. Experimental studies on minerals with varying solubility, from halide salts to phosphates, silicates and oxides will be used to identify the rate-limiting steps of the overall fluid-mediated transformation process. The mechanisms of this process will be identified by using high resolution analytical and imaging techniques.

The network as a whole will provide a minimum of 480 person-months of Early Stage and Experienced Researchers whose appointment will be financed by the contract.

The training objectives are to provide the participating young researchers with an innovative multidisciplinary training for careers either in industry or in academia. The broad applicability of the Δ-MIN training will ensure that all trainees will not only be aware of the other possible applications of their personal projects but will be qualified for further positions in diverse fields.

Concept of the Project

The fundamental issues of how minerals (and solids in general) equilibrate in the presence of a fluid phase are poorly understood, and despite the wide-ranging applications in both industry and basic research, training in this area remains fragmentary. The principles which connect problems such as the interaction of minerals with CO2-saturated water, the durability of nuclear waste materials, the remediation of contaminated ground water, and the mineral replacement reactions which can destroy our stone-based cultural heritage, are not being taught in any single earth sciences, chemistry or chemical engineering program. This need is addressed by the Δ-MIN research and training program through the combination of industrial and academic training at all levels: from university-industry linked studentships, to co-direction of specific research projects designed so that they can be of greatest benefit to solving such industrial, environmental, cultural and scientific problems.

Understanding the mechanism of the transformation of one solid phase to another is fundamental to natural and industrial processes. Almost every substance can exist in two or more structurally different phases, depending on the temperature and pressure. The study of phase transformations is well established and focuses on determining the thermodynamics (which phase is more stable under which conditions), and the kinetics (why metastable phases exist outside their stability field) of changes from one structure to another. While the thermodynamic parameters of most phases are comparatively straightforward to determine either experimentally or by computation, determining the kinetics is more problematic and requires detailed information on the reaction mechanisms.

There are two main routes for phase changes between solid structures. In the first, the less stable solid undergoes an internal rearrangement of molecules or atoms such that the transformation occurs in the solid state. Solid state phase transformations have been widely studied, due to the historical interest in metals, alloys and refractory ceramics. However, in the presence of a solvent, a second mechanism is available, whereby the less stable phase dissolves and the more stable phase nucleates and grows from solution. Such solvent-mediated phase transformations may seem intrinsically simpler to understand, but they are currently very poorly understood because the process involves the intimate coupling of the thermodynamics and kinetics of a variety of distinct reactions occurring in both the solid and the fluid phases.

The most common fluid phases in the crust of the Earth are aqueous solutions whose chemical composition may be quite complex. Examples include sea-water, organic-rich or polluted ground-water or acid rain. The interaction of such solutions with solids can induce a change in their structure and chemistry such that a new solid phase is produced which is more stable than the parent phase.

What’s new in phase transformations? – Interface-coupled dissolution-precipitation reactions.

Interface-coupled dissolution-reprecipitation reactions are fundamentally different from solid-state phase transformations. Although the start and end products may be the same, as defined by the thermodynamics, the rates of interface-coupled dissolution-reprecipitation may be orders of magnitude faster and very importantly, the mechanism generates a transient porosity in the product while preserving the external solid volume of the system. This mechanism, only very recently defined, is applicable not only to polymorphic systems  but is a general mechanism of reequilibration of solids in the presence of a fluid phase and allows interpretation of many diverse textural observations made in natural rocks and chemical systems. The generation of porosity explains rapid fluid and mass transport through impermeable solids and provides a new basis for understanding the role of fluids in phase transformations.

Understanding these mechanisms requires an interdisciplinary approach, bringing together all aspects of fluid-solid interaction – thermodynamics of the solids and fluids, kinetics of dissolution and precipitation, properties and reactivity of surfaces, epitaxial growth and crystallographic relations, reaction induced permeability in solids, fluid flow through porous media etc. The broad applications of this mechanism, and the opportunities for a better understanding of a wide range of related processes, will provide a challenging and highly stimulating research and training environment for the Δ-MIN ITN.

Overall Approaches and Methodology

Scientific approach

Δ-MIN is concerned with mechanisms of reequilibration of minerals under changing physical and chemical conditions, primarily in the presence of an aqueous fluid phase. As such it includes research projects which cover a broad range of complementary methodologies: experimental work on fluidmineral interaction, field-based studies of fluidmineral interaction in nature, thermodynamic and kinetic modeling.

The central feature of Δ-MIN is that a common principle unites a wide range of phenomena in different interdisciplinary fields and the primary aim of the whole project is to provide a central framework to describe and explain the mechanisms underlying these phenomena.

Training approach

Network level training courses and industrial secondments will provide the young researchers with a wide multi-faceted training to underpin their professional development: from ensuring the basic theoretical background and hands-on training on analytical equipment, to experience in problem-solving. An appreciation of the different requirements of industry and academia as a career will also be a recurrent theme reinforced by training contributions from industry partners related to their sub-projects. ESR and ER mobility between participating teams will be required by the design of the individual projects, with a choice of training options on the whole range of state-of-the-art equipment available within the network. The young researchers will be given opportunities for network level and externally provided complementary training in project management, proposal writing, publication techniques and oral presentations, as well as an awareness of the importance of IPR management in collaborative projects. Presentation of results at annual international conferences will be an essential part of the training, and will identify Δ-MIN participants as a coherent group.

Research Facilities available to all Δ-MIN participants and fellows:

The combined experimental facilities available for Δ-MIN include a wide range of apparatus for fluid-induced mineral reactions at temperatures from ambient to 12000C as well as dissolution-precipitation cells where observations can be made in situ from a microscopic scale to the atomic scale. In situ high-magnification analysis of the dissolution-precipitation reactions will also be performed using Environmental Scanning Electron Microscopy (ESEM) equipped with heating and cooling stages.

State-of-the-art facilities exist in the network for characterising both reactive fluids as well as solid reaction products. For fluids: Atomic Absorption Spectrometry, Inductively coupled plasma optical emission spectrometry, Mass spectrometry, Ion Chromatography and Electroanalytical methods. For solids: Standard X-ray diffraction methods, electron probe microanalysis (EPMA), and scanning electron microscopy (SEM), the most advanced transmission electron microscopes (TEM) with in column energy filters. FIB (Focussed Ion Beam) methods will be used for TEM preparation. Mercury intrusion porosimetry and N2 adsorption are available to study pore systems. Changes in the trace element and isotope chemistry across reaction interfaces will be studied by Laser ablation ICP-Mass spectrometry.

Imprint | © 2008 DELTA-MIN
Corrensstr. 24 · 48149 Münster, Germany
Tel.: +49 251 83-33464 · Fax: +49 251 83-38397