Crystallization, Particle Design and Hydrometallurgy

Environmental Engineering and Reactor Technology

Crystallization, Particle Design and Hydrometallurgy

Our research group focuses on both fundamental and applied research in the fields of crystallization and hydrometallurgy. By strengthening our fundamental understanding in these areas, we aim to contribute to the advancement of sustainable technologies such as recycling of raw materials, waste treatment and water management; as well as functional material design for a wide array of applications.

 

Hydrometallurgy

We are a partner in the HYDROMET project that aims to develop hydrometallurgical education and research in Norway. It is financed by The Norwegian Research Council and Norwegian industry, and is a collaboration between research institutions NTNU, UiO, IFE and SINTEF, and industrial partners. Our focus in this project is to enhance product quality in hydrometallurgical zinc and nickel production by impurity removal. The main tasks for the project include removal of impurities by iron hydroxide and nickel sulfate precipitation, and filtration. By simulating the industrial process conditions in a continuous reactor set-up, we have shown that supersaturation and temperature have significant effect on the crystal growth and hence the filtration performance of iron hydroxide precipitates. Uptake potential of various impurities in nickel sulfate is studied by cooling crystallization, in order to understand the effects of different impurities on the crystal growth and the mechanism of incorporation.

Hydrometallurgical processes for Lithium Battery Recycling (LIBRES)

Norway has the highest electrical vehicle (EV) fraction of new car sales in the world. Lithium ion batteries (LIBs) have a long lifetime, in many cases above ten years, but eventually the batteries will reach end of life. Proper recycling is then required. There are already companies in Europe, USA and Asia that process end-of-life LIBs. Only a couple are large players, and these process LIBs in existing processes designed for other purposes or in only slightly modified processes. The problem with these processes is that material recovery is low, below 50%, and energy consumption and manual labor intensity is high. Most importantly, in the current state of the art processes, lithium is not recovered. Norway is in a special position to develop and commercialize the next generation LIB recycling process.

The LIBRES project at Department of Chemical Engineering (IKP), NTNU aims to develop and commercialize a new LIB recycling process that shall be suitable for the large future volumes and have a much higher material recovery rate than today's state-of-the-art. Research within our group is focussed on hydrometallurgical routes to extract valuable metals, such as cobalt, lithium, nickel, copper, and manganese in addition to graphite and iron from spent LIBs using unit operations such as liquid-liquid extraction, leaching and so on. The project further aims to develop methods for chemical processing of the active cell materials in order to ensure high recovery rate, high value of recovered products and low cost. The project owner is Norsk Hydro ASA, other commercial partners include Batteriretur, Glencore Nikkelverk and Keliber OY all of whom have separate interests along the LIB recycling value chain. R&D partners include Elkem Technology, IME RWTH Aachen (Germany), Agder University and NTNU.

This project also kicks off activities under the recently established HYPROS Gemini Centre between NTNU, University in Oslo and SINTEF.

 

Biomineralization - Calcium phosphate mineralization

Mineral formation in biological systems is a complex process, which involves organic and inorganic molecules to regulate the nucleation, growth, morphology and organization of biogenic minerals. The comprehensive control mechanisms in natural biomineralization processes result in advanced materials with high functionality and offer a valuable insight and inspiration for synthetic material design. Thus, a subsistent step in the field of biomineralization studies has been the use of extended knowledge on organic matrix- mineral interactions to design smart materials with well-defined, function-oriented structures.

We have been investigating crystallization of calcium phosphate (CaP) systems in the presence of alginate-based organic matrix molecules, in relation to biomaterial design in collaboration with the Departments of Physics and Biotechnology. CaP precipitation is a complex process that depends on various parameters, and due to the high number of variables, it is difficult to predict the exact mechanism of CaP formation in any given matrix. Our studies have focused on understanding fundamental mechanisms of nucleation, growth and phase transformations of calcium phosphates by coupling solution chemistry analyses with advanced characterization techniques. This work has provided quantitative data on reaction kinetics as well as a qualitative understanding on the acting mechanisms of alginate additives via a systematic evaluation of the intermolecular interactions between the alginate molecules and inorganic phases, where the active roles of the functional groups have been evaluated. This feature can be employed to construct complex, highly hierarchical biomaterials with controlled properties such as mineralization potential and mechanical performance.

Synthesis, Characterization, Functionalization and Applications of Metallic and Polymeric Nanomaterials

Several projects are currently undergoing within this thematic area.

DNA based Hydrological Tracers for Water Management

Societal demand for water safety is continuously increasing, being it resilient against flood/droughts, clean water for ecosystems, recreation or safe drinking water. Robust methods to measure temporal and spatial patterns of water and contaminant pathways are still lacking. The project aims to develop and apply inert, robust, environmentally friendly DNA-tracers in water resources practice and an innovative coupled model approach to capture dynamics in hydrological pathways and their effects on water quality. Together, DNA-tracers and travel time-based modelling will improve protection of water resources and drinking water production sites and help safely closing water and substance cycles and use of alternative water sources.

The project owner is TU Delft and the research is driven through a strong consortium including several academic and industrial partners in Netherlands and Norway. Our group’s main role in the project is to develop DNA based magnetic nanoparticles that will be used as hydrological tracers.

Understanding Growth of Anisotropic Nanoparticles

Au nanoparticles exhibit localized surface plasmon resonance (LSPR) that provide wide applications in photothermal therapy, imaging and other theranostic processes. Although the properties improve when anisotropy sets in, their growth mechanisms are not fully understood owing to different synthesis conditions used across various labs and challenges to explicitly characterize their synthesis and growth using nucleation and growth theories. However, these materials find advanced applications upon functionalization with various moieties that make them interesting candidates for synthesis and application.

In this project, several solution–based methods are being used to synthesize anisotropic gold nanostructures with an aim to understand their growth mechanisms. The effect of supersaturation, pH, temperature, additives among other factors is being investigated to control growth. These are being characterized using standard techniques available at NTNU Nanolab, Crystallization Lab and Ugelstad Lab that include TEM, DLS, UV-Vis, FTIR, Raman, Nanosight among others. The growth mechanisms will also be investigated using molecular modelling techniques. The project is being run in collaboration with Ugelstad Laboratory and NTNU NanoLab.

Multifunctional Nanomaterials for Biomedical Applications

Recent years have seen an increasing demand of smart nanomaterials in diagnosis, therapy, quality control, resource management among others that are capable of carrying out several functions simultaneously with precision and accuracy. In most such applications, integrating several functionalities into a single nanoconstruct is desired, leading to the formation of smart materials. In essence, a single nanoconstruct might be able to remain in circulation for long, possess optically detectable properties (tracking), bind to a specific molecule, undergo a detectable change in properties and so on. Majority of such constructs require optimization of synthesis and encapsulation steps to achieve unprecedented functions.

In this project, several methods are being used to form stimuli-responsive nanogels coupled with inorganic NPs that can be triggered to release a cargo of interest in a controlled manner. Primary focus is on optimization of system parameters in order to modify the physicochemical properties of the constructs. Following an optimized synthesis protocol with detailed understanding of the growth mechanisms, different biomolecules like DNA, proteins will be encapsulated to estimate loading properties of these nanoconstructs. In the final part of the project, the multifunctional NPs will be evaluated for different biomedical applications such as drug delivery, bioimaging and so on. The project runs in collaboration with Ugelstad Laboratory, NTNU NanoLab and Department of Materials Science and Engineering, NTNU.

Investigations of spherulitic growth in solutions – a mechanism for polycrystalline particles

According to the classical theory of crystallization, crystal growth occurs via continual addition of building units on the crystal surfaces and their incorporation into the lattice sites. In the last decades, revelation of complex morphologies and surface features with nanosized subunits with advanced characterization techniques have evoked alternative hypotheses to classical growth mechanisms that employ particle aggregation models. Meanwhile, same observations are elucidated within the classical models by extending the fundamental approach of classical theory to explain the formation of dendritic and spherulitic morphologies along with polyhedral crystals. Since the fundamental frameworks behind the classical and aggregation-based pathways are divergent, the effective parameters they define for growth kinetics and mechanism also varies.

We have collected experimental proof for spherulitic growth from solutions in contrast to literature claims of nano-aggregation as responsible for the same type of particles. Spherulitic growth is usually associated with melt crystallization but our findings show that it is a general mechanism in solid material formation. The time-dependent evolution of spherulitic growth is shown for calcium carbonate and supporting evidence for classical growth mechanism is provided by seeded experiments of gold spherulites. Further work is in progress to prove the validity of this growth process for numerous crystalline compounds, irrespective of the chemical nature of the constituents.

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