Removal of chloride from MSWI fly ash
Journal
Journal of Hazardous Materials
Journal Volume
237-238
Pages
116-120
Date Issued
2012
Author(s)
Abstract
The high levels of alkali chloride and soluble metal salts present in MSWI fly ash is worth noting for their impact on the environment. In addition, the recycling or reuse of fly ash has become an issue because of limited landfill space. The chloride content in fly ash limits its application as basis for construction materials. Water-soluble chlorides such as potassium chloride (KCl), sodium chloride (NaCl), and calcium chloride hydrate (CaCl2·2H2O) in fly ash are easily washed away. However, calcium chloride hydroxide (Ca(OH)Cl) might not be easy to leach away at room temperature. The roasting and washing-flushing processes were applied to remove chloride content in this study. Additionally, air and CO2 were introduced into the washing process to neutralize the hazardous nature of chlorides. In comparison with the water flushing process, the roasting process is more efficient in reducing the process of solid-liquid separation and drying for the reuse of Cl-removed fly ash particles. In several roasting experiments, the removal of chloride content from fly ash at 1050°C for 3h showed the best results (83% chloride removal efficiency). At a solid to liquid ratio of 1:10 the water-flushing process can almost totally remove water-soluble chloride (97% chloride removal efficiency). Analyses of mineralogical change also prove the efficiency of the fly ash roasting and washing mechanisms for chloride removal. © 2012 Elsevier B.V.
Subjects
Aeration; Carbonation; Chloride; MSWI fly ash; Roasting; Water-flushing
Other Subjects
Alkali chlorides; Ash particles; Chloride; Chloride contents; Chloride removal; Impact on the environment; Mineralogical changes; MSWI fly ash; Potassium chloride; Removal of chloride; Roasting; Roasting experiments; Roasting process; Room temperature; Solid-liquid separation; Solid-to-liquid ratio; Soluble metals; Washing process; Water-flushing; Calcination; Calcium chloride; Carbon dioxide; Carbonation; Hydrates; Leaching; Sodium chloride; Washing; Water aeration; Water conservation; Fly ash; calcium carbonate; calcium chloride; calcium oxide; calcium silicate; carbon dioxide; chloride; potassium chloride; sodium chloride; aeration; alkalinity; carbon dioxide; chloride; construction material; environmental impact; flushing; fly ash; landfill; pollutant removal; potassium chloride; recycling; separation; sodium chloride; aeration; article; fly ash; hazardous waste; incineration; mineralogy; MSWI fly ash; municipal solid waste; recycling; room temperature; X ray diffraction; Chlorides; Coal Ash; Incineration; Industrial Waste; Recycling; Waste Management
Type
journal article