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Pen-chi Chiang – 1st expert on this subject based on the ideXlab platform
deployment of Accelerated Carbonation using alkaline solid wastes for carbon mineralization and utilization toward a circular economyACS Sustainable Chemistry & Engineering, 2017Co-Authors: Kinjal J Shah, Yi Hung Chen, Minghuang Wang, Pen-chi ChiangAbstract:
This study suggests that the waste-to-resource supply chain can offer an approach to address simultaneously the issues of waste management and CO2 emissions toward a circular economy. Alkaline solid wastes can be used to mineralize CO2 through an Accelerated Carbonation reaction, especially if the wastes are generated near the point source of CO2, to achieve environmental and economic benefits. To enhance the performance of Accelerated Carbonation, a high-gravity Carbonation process using a rotating packed bed reactor was developed and deployed. Due to additional energy consumption in high-gravity Carbonation, the environmental benefits and economic costs should be critically assessed from a life-cycle perspective. In this study, the resource potential of alkaline solid wastes in Taiwan was first determined for CO2 mineralization and utilization using the high-gravity Carbonation process. Then, the performances of the process from engineering, environmental, and economic perspectives were evaluated and ex…
Principles of Accelerated Carbonation ReactionCarbon Dioxide Mineralization and Utilization, 2017Co-Authors: Pen-chi ChiangAbstract:
Industrial alkaline solid wastes are ideal Accelerated Carbonation materials due to their availability and low cost. These materials are generally rich in calcium content and often associated with CO2 point source emissions so no mining is needed and the consumption of raw materials is avoidable. This chapter provides the principles and definitions of Accelerated Carbonation reaction using alkaline solid wastes. Two types of Carbonation processes, i.e., direct and indirect Carbonation, are briefly discussed from the theoretical considerations, including process chemistry and key performance indicators. The performance and application of both direct and indirect Carbonation processes can be found in detail in Chap. 8.
integrated and innovative steel slag utilization for iron reclamation green material production and co2 fixation via Accelerated CarbonationJournal of Cleaner Production, 2016Co-Authors: Rahul Adhikari, Pen-chi Chiang, Yi Hung Chen, Ping LiAbstract:
Abstract Huge amounts of iron and steel slags are generated annually worldwide from integrated manufacturing processes and/or the electric arc furnace. However, conventional uses of untreated iron and steel slags in civil engineering have encountered several technological barriers, such as fatal volume expansion, heavy metal leaching and low cementitious property of slag. In this study, the physico-chemical properties of four different types of slag, blast furnace slag, basic oxygen furnace slag, electric arc furnace slag and ladle refining furnace slag, are illustrated. The challenges and barriers in direct use of steel slags in civil engineering are comprehensively summarized. To overcome the barriers of slag utilization, an Accelerated Carbonation process is proposed and reviewed in terms of theoretical perspectives and practical considerations. Since diluted CO2 in flue gas can be directly introduced for Carbonation, additional environmental and economic benefits such as CO2 emission reduction are obtained. In addition, the performance of various new carbonated slags or products is systematically reviewed, in terms of changes in the physico-chemical properties of carbonated slag. To facilitate the industrialization of Accelerated Carbonation, several suggestions are made regarding future research directions.
Paula Carey – 2nd expert on this subject based on the ideXlab platform
Accelerated Carbonation treatment of industrial wastesWaste Management, 2010Co-Authors: Peter John Gunning, Colin Hills, Paula CareyAbstract:
The disposal of industrial waste presents major logistical, financial and environmental issues. Technologies that can reduce the hazardous properties of wastes are urgently required. In the present work, a number of industrial wastes arising from the cement, metallurgical, paper, waste disposal and energy industries were treated with Accelerated Carbonation. In this process Carbonation was effected by exposing the waste to pure carbon dioxide gas. The paper and cement wastes chemically combined with up to 25% by weight of gas. The reactivity of the wastes to carbon dioxide was controlled by their constituent minerals, and not by their elemental composition, as previously postulated. Similarly, microstructural alteration upon Carbonation was primarily influenced by mineralogy. Many of the thermal wastes tested were classified as hazardous, based upon regulated metal content and pH. Treatment by Accelerated Carbonation reduced the leaching of certain metals, aiding the disposal of many as stable non-reactive wastes. Significant volumes of carbon dioxide were sequestrated into the Accelerated carbonated treated wastes.
Accelerated Carbonation for the treatment of landfilled cement kiln dust, 2008Co-Authors: Aurora Antemir, Peter Gunning, Colin Hills, Paula CareyAbstract:
Accelerated Carbonation Technology (ACT) can be used to treat a wide range of alkaline wastes and metal-contaminated soils by exposing them to a carbon dioxide rich atmosphere in a way that promotes the massive precipitation of calcium carbonate. The material obtained has improved physical and chemical characteristics. This work presents the characterisation of historically deposited cement kiln dust (CKD) and its potential reactivity with carbon dioxide gas. The CKD investigated originated from a landfill, up to one hundred years old. The bulk chemical composition was determined by X-ray Fluorescence (XRF), the mineralogy of the untreated and carbonated CKD by X-ray Diffractometry (XRD) and the change in microstructure upon Carbonation was examined by Scanning Electron Microscopy (SEM/EDS). Key characteristics of treated and untreated CKD such as carbon dioxide uptake, pH, and moisture content are presented and discussed.
Accelerated Carbonation of municipal solid waste incineration fly ashesWaste Management, 2007Co-Authors: Xiaomin Li, Paula Carey, Colin Hills, Marta Fernandez Bertos, Stef SimonAbstract:
As a result of the EU Landfill Directive, the disposal of municipal solid waste incineration (MSWI) fly ash is restricted to only a few landfill sites in the UK. Alternative options for the management of fly ash, such as sintering, vitrification or stabilization/solidification, are either costly or not fully developed. In this paper an Accelerated Carbonation step is investigated for use with fly ash. The Carbonation reaction involving fly ash was found to be optimum at a water/solid ratio of 0.3 under ambient temperature conditions. The study of ash mineralogy showed the disappearance of lime/portlandite/calcium chloride hydroxide and the formation of calcite as Carbonation proceeded. The leaching properties of carbonated ash were examined. Release of soluble salts, such as SO4, Cl, was reduced after Carbonation, but is still higher than the landfill acceptance limits for hazardous waste. It was also found that Carbonation had a significant influence on lead leachability. The lead release from carbonated ash, with the exception of one of the fly ashes studied, was reduced by 2–3 orders of magnitude.
Colin Hills – 3rd expert on this subject based on the ideXlab platform
Enhancement of Accelerated Carbonation of alkaline waste residues by ultrasound.Waste Management, 2016Co-Authors: Paris Araizi, Colin Hills, Alan Maries, Peter Gunning, David WrayAbstract:
Abstract The continuous growth of anthropogenic CO2 emissions into the atmosphere and the disposal of hazardous wastes into landfills present serious economic and environmental issues. Reaction of CO2 with alkaline residues or cementitius materials, known as Accelerated Carbonation, occurs rapidly under ambient temperature and pressure and is a proven and effective process of sequestering the gas. Moreover, further improvement of the reaction efficiency would increase the amount of CO2 that could be permanently sequestered into solid products. This paper examines the potential of enhancing the Accelerated Carbonation of air pollution control residues, cement bypass dust and ladle slag by applying ultrasound at various water-to-solid (w/s) ratios. Experimental results showed that application of ultrasound increased the CO2 uptake by up to four times at high w/s ratios, whereas the reactivity at low water content showed little change compared with controls. Upon sonication, the particle size of the waste residues decreased and the amount of calcite precipitates increased. Finally, the sonicated particles exhibited a rounded morphology when observed by scanning electron microscopy.
Ultra-rapid hardening of cement by Accelerated Carbonation – Past, present and future, 2015Co-Authors: Alan Maries, Colin HillsAbstract:
The ancient Greeks and Egyptians may have unwittingly employed Accelerated Carbonation with the polishing technique that they used to achieve seamless crack-free linings in lime-based pipe and stucco work. However, it was not until the advent of Portland cement in the mid-19th century that Carbonation with gaseous CO2at atmospheric pressure was proposed as a means of accelerating the setting and hardening of mortar and concrete.
In the 1970s the first attempts were made to achieve a more thorough scientific understanding of the process, most notably in the USA by Berger and colleagues, but also by researchers in the USSR, Israel and Sweden.
The authors’ own development of a Carbonation process to accelerate the hardening of precast concrete dates from over 30 years ago, when lowering atmospheric emissions of CO2 by sequestration was not yet an issue. But today, with global cement production increasing relentlessly at around 8% per annum to a current total of 4 Gtonnes and releasing a similar mass of CO2, emission reduction is now a pressing concern in the cement and concrete sector.
This paper will report on current commercial operations involving Accelerated Carbonation of concrete and will look forward to challenges and opportunities in a low-carbon future.
Carbon negative: First commercial application of Accelerated Carbonation technology, 2014Co-Authors: Peter Guning, Colin HillsAbstract:
Carbon dioxide gas can be used as a resource to rapidly harden cementitious materials and manage the risks associated with hazardous waste and contaminated soil. The process is known as Accelerated Carbonation Technology or ACT. Carbon dioxide primarily combines with calcium and/or magnesium minerals present in many industrial thermal residues to form carbonates; this reaction can also be promoted by the addition of, for example, Portland cement. Carbon8 Systems Ltd. was formed in 2006 as spinout-company of the University of Greenwich to commercialise ACT. Carbon8 has applied ACT to hazardous wastes in the production of non-hazardous construction products.By using the Carbon8 process, industrial thermal residues are solidified and stabilised in a hardened pellet form. The pelleted product is a direct substitute for natural aggregate, and can be used in the production of concrete construction blocks. From 2009 to 2012, a series of pilot and full-scale demonstrations of the technology were carried out. The aggregates produced were rigorously tested and given ‘end-of-waste’ designation by the Environment Agency. In early 2012, a bespoke commercial plant was commissioned at Brandon in Suffolk, UK, operated by Carbon8 Aggregates Ltd. This plant, the first of its kind anywhere in the world, produced 24,000 tonnes of aggregate from municipal solid waste incineration (MSWI) air pollution control residues (APCr) in its first year. In 2014, a second production line was added to the Brandon facility, increasing its capacity to 50,000 tonnes per year. The aggregate is supplied to Lignacite, the UK’s largest independent concrete block manufacturer, and other companies. The ACT-produced aggregate is carbon negative as it contains more imbibed carbon than is generated by its production. Consequently, the concrete construction blocks produced by Lignacite are also carbon negative, and are marketed under the name: ‘Carbon Buster’. Plans are at an advanced stage for the construction of a second and third production facility in the UK. These are scheduled to be operational by mid-2015 and will increase aggregate production to 200,000 tonnes per year. The present work discusses the development of the Carbon8 process and describes the commercial application of Accelerated Carbonation technology for the production of sustainable carbon-negative construction materials.