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Fourth International Conference on Accelerated Carbonation for Environmental and Materials Engineering (ACEME 2013)
The KU Leuven recently hosted the 4th Edition of the International Conference on Accelerated Carbonation for Environmental and Materials Engineering. ACEME 2013 followed the three successful previous editions held in: London/UK (Jun-2006), Rome/Italy (Oct-2008), and Turku/Finland (Nov-2010). The ACEME conferences aim at promoting research and development activities on accelerated carbonation at an international level, favoring knowledge sharing and critically discussing future development and implementation in the field.
The objectives of the 4th Edition were to communicate and discuss the latest advances in the field of theoretical and applied research on accelerated carbonation of various types of natural materials and industrial residues. Processing conditions, product properties and (on-line) analysis at lab-, pilot- and full-scale were the key focus themes of the conference. The conference also aimed at promoting mineral carbonation in the context of Carbon Capture and Storage (CCS) and Carbon Capture and Utilization (CCU).
A total of 115 participants from twenty-three countries were represented. Obviously Belgium had the largest delegation (24), followed by Italy and the UK (12 each). Participants came from as far away as Australia, Brazil, Mexico, South-Africa, South-Korea, Taiwan and the US, making it the most international edition to date. There was also a great blend of participants from academia, research institutes, and a fair share of industrial delegates (17%). Attendants had the opportunity to view 42 oral presentations, of which 3 keynote lectures, and 20 poster presentations. The conference was kindly sponsored by Arcelor Mittal, Lhoist, Redco and Solvay.
The conference kicked off with an evening reception on the 9th of April. About 50 people took the time to come over and wander through the engines and other mechanical devices that are exhibited in the Machine Room of the Thermotechnical Institute of the KU Leuven.
On the 10th of April the lectures focused on the principles and analysis of mineral carbonation. The keynote lecture of the day was given by Carlos Rodriguez-Navarro from the University of Granada. Carlos discussed the intricacies of calcium hydroxide carbonation. Although this appears to be a very simple reaction, there are still a number of complications especially regarding the environment in which the carbonation takes place. In solution, the reaction proceeds via prenucleation clusters from amorphous precipitated carbonate to calcite. In the solid state the portlandite crystals are pseudomorphically replaced via a coupled dissolution/precipitation mechanism. These reaction paths have implications for the rate and conversion of the reaction. In a second lecture Alan Maries et al. moved on to study a large number of potential catalysts to accelerate the reaction. Hypochlorite appeared to give the best results. Further on there were a number of presentations that highlighted the use of biological catalysts (Cizer et al.; Swanson et al.; Oliver et al.; Bundeleva et al.) such as enzymes and bacteria, a rather new development compared to the previous conferences. Throughout the day, other lectures focused process conditions such as relative humidity (Wilson et al.; Highfield et al.; Montes-Hernandez et al.), additives (Hassan et al.; Santos et al.), temperature and carbon dioxide pressure (Oskierski et al.; Hassan et al.; Montes-Hernandez et al.), either in the case of natural carbonation or industrially accelerated carbonation. Boone et al. showed results on the use of X-ray tomography to link the progress of the carbonation reaction with the porosity. The day ended with a progress report on a pilot-scale installation in the US to carbonate coal combustion fly ashes using flue gas from the same power plant facility (Reddy et al.), and with a critical view of Hills et al. on the feasibility of carbonation technology scale-up and the need for a market-driven approach. At this moment, the market pushes carbonation more towards the benefit of new materials than towards that of CO2 sequestration.
On April 11, the keynote lecture of Mercedes Marato-Valer from Heriot-Watt University followed up on that feasibility. A decentralized scheme for the carbonation of waste materials with flue gases from nearby industrial plants is an attractive approach to kick-start the uptake of carbonation technologies by the industry at large, although the capacities for potential CO2 sequestration should be carefully determined. It becomes clear that mineral carbonation has its place in the portfolio of CO2 sequestration technologies, with high-value but low-output products being produced for niche markets, while applications such as land/mine reclamation for low-value but high-throughput products potentially arising for large-scale sequestration projects. After this keynote lecture, the poster presenters were given the opportunity to highlight their work with two-minute ‘intensified’ presentations. These rapid poster presentation pitches appeared to be very successful, given the large crowd near the poster panels during the coffee break immediately after this session. Further on during the day and also the following day, kinetic, mineralogical and leaching studies were presented for a variety of materials such as serpentine (Boschi et al.; Ghoorah et al.; Hariharan et al.), hydrated cement (Kinoshita et al.), asbestos (Gadikota et al.), oil shale ash (Uibu et al.), metallurgical slags (Baciocchi et al.; Costa et al.; Dri et al.) and mining residues (Assima et al.; Bodenan et al.), as well as synthetically produced reference materials (Bodor et al.). More details were given on appropriate process conditions, which was the main theme of the day.
At the end of the day, Koen Van Balen and Jan Elsen guided the participants through the Beguinage, a UNESCO-protected world heritage site in the centre of Leuven. This tour was followed by an exquisite dinner in the Faculty Club, where, following the tradition of the conferences in Rome and Turku, Rein Kuusik of the Tallinn University of Technology honored the guests with some folk tales and a beautiful Estonian song. It was also revealed that the next conference will be held in 2015 in New York, USA.
The last day of the conference was dedicated to applications. The keynote lecture was given by Sigurdur Gislason (University of Iceland) who coordinates the CarbFix project on mineral CO2 storage in basalt layers underground. Studies of the trapping system (solubility–mineral) are essential to assess the long-term storage potential of the underground layers. Lab experiments and geochemical modeling studies are now being complemented with field injection studies, which have started early 2012. As is the case for ex-situ mineral carbonation, the capture step is the most expensive. However, this might prove to be an advantage for ex-situ mineral carbonation processes, where capture and separation are less crucial. In the following session a number of applications were described such as the production of construction blocks (Monkman et al.; Salman et al.), aggregates (Baciocchi et al.; Araizi et al.) precipitated calcium or magnesium carbonate (Velts et al.; Zevenhoven et al.) silica for paper coating (Teir et al.) and sorbents (Chiang et al.). Throughout the conference, also some novel technologies were presented as well, e.g. rotating packed bed (Pan et al.), ultrasound processing (Santos et al.) and a gravity pressure vessel (Knops et al.). More work on these intensified technologies should be performed, as they may provide the technological leap needed to make mineral carbonation industrially feasible.
After a full three days of lectures and discussions, a number of trends that are becoming clear can be identified: the rise of biotechnology in studies related to mineral carbonation, the emergence of (successful) commercial technologies, the need to combine the benefits of materials valorization with flue gas utilization. For the next conference in New York, focus will have to be given to economical and ecological assessment, interaction with decision makers, and further technology intensification.
For those who missed the conference but are still interested in its domain, copies of the proceedings (551 pages!) are still available for purchase (email@example.com) and information on the conference in 2015 will be made available on the ACEME 2013 website: cit.kuleuven.be/aceme13. Select papers reporting novel research from ACEME 2013 will be published in an upcoming special issue of Minerals Engineering.
Tom Van Gerven & Rafael Santos
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