Long-term leaching characteristic study of coal processing waste streams. (June 2020)

• Record Type: Journal Article
• Authors: Rezaee, Mohammad; Honaker, Rick. Q.
• Is Part Of: Chemosphere. Volume 249(2020)
• Publication Date: 2020-06
• Subjects: Coal waste disposal -- Refuse -- Leaching -- Pyrite oxidation -- Trace elements; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.126081
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: A study of the mobility of major and potentially hazardous trace elements from coal processing waste materials was conducted using two types of leaching tests. The baseline leaching test simulates stable waste storage under water, whereas the kinetic test models the storage of waste under more variable conditions including intermittent exposure to air and variations in humidity. Coarse and fine refuse materials were obtained from three commercial coal preparation plants that were being used to upgrade US bituminous run-of-mine coal containing low-to-high amounts of pyritic sulfur. X-ray diffraction analyses revealed a large variation in mineralogy between the coarse and fine refuse streams due to the mineral fractionation that occurs in the processing units and plant. The coarse refuse samples contained higher pyrite contents while the fine refuse samples had high clay content and a minor amount of calcite. This variation in mineralogy resulted in relatively large difference in the leaching characteristics of the waste streams. The most acidic pH and highest release of trace elements were observed in the leachate of coarse refuse containing medium-to-high amounts of coal pyrite, while the fine refuse samples released lower amounts of trace elements in their circumneutral leachate. The least amount of trace elements was observed in the leachate of low pyritic refuse streams. The test data suggested that the most effective disposal practice for coal waste material is segregation and isolation of the coal pyrite and co-disposal of the coarse and fine refuse streams. Highlights: Mobility of major and trace elements from coal processing waste materials was studied. Detailed characterization, baseline and kinetic column leaching tests were performed. A large difference in mineralogy and leaching characteristics of the waste streams was found. The most effective disposal practice for coal waste stream was formulated.