Improvement of environmental quality of coal fly ash by applying forced leaching

✍ Scribed by H.W. Nugteren; M. Janssen-Jurkovı́cová; B. Scarlett

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 80 KB
• Volume: 80
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/s0016-2361(00)00163-0

✦ Synopsis

A coal ¯y ash containing leachable trace elements in amounts higher than allowed by Dutch law for its free application as granular building material was subjected to forced leaching using water, citrate-, oxalate-, EDTA-and carbonate-solutions. With water only, the free lime and substantial amounts of Mo (30%), Se (20±40%) and SO 22 4 (40±50%) are removed. Using the extraction agents, these percentages increase to 60±90% and in addition 15±20% Cr, V and Sb are removed. The environmental quality of the washed ¯y ash was checked with the Dutch standard leaching test (NEN7343). Leachability of Mo, Se and S decreased by a factor of 2±4 after washing with water and a factor 2±18 (including Cr) after washing with the extracting agents. Removing extractants and metals remaining in the moisture after ®ltration will further decrease leaching. For a feasible process reduction of reagent consumption and simple methods for process-water recycling are needed.