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3422es_e.htm at mend20WIrcan.gc.ca • Page 1 of 4 <br /> Characterization and Stability of Acid Mine Drainage Tratment Sludge <br /> MEND Report 3.42.2 <br /> May 1997 <br /> SUMMARY <br /> Acid mine drainage (AMD) and other acidic metalliferous effluents are commonly <br /> treated by the mining and metallurgical industries by lime neutralization. Upon <br /> neutralization, metals precipitate out of the effluent as hydroxides. This neutralization <br /> produces voluminous hydroxide sludges with low solids content (frequently < 5%). <br /> Despite recent improvements to the traditional neutralization method, it is estimated <br /> that as much as 6.7 million cubic metres of sludge are produced annually in Canada. In <br /> addition, the Canadian mineral industry is faced with questions related to the long term <br /> stability of AND treatment sludges, and their environmentally acceptable disposal. <br /> There is a need to develop standard sampling, handling and characterization protocols <br /> for AMD treatment sludges. A systematic method of assessing sludges with respect to <br /> their chemical, physical and leaching characteristics is necessary for estimating the <br /> sludge stability and for making informed decisions for disposal. <br /> • This report summarizes work that has been carried out in three areas: <br /> • a site survey and sampling campaign of AMD treatment sludges at 11 Canadian <br /> mine sites; <br /> • a detailed characterization of the collected sludges including physical, chemical, <br /> mineralogical and thermal analyses; and <br /> • the leaching of the sludge samples using two distinct tests in association with a <br /> review of current hazardous waste regulations. <br /> This report provides a data bank of lime treatment sludge characteristics which has <br /> been applied here in the discussion of sludge stability. Furthermore, this information <br /> may be used to assist operators, researchers and regulators in the development of <br /> improved treatment processes, effective disposal methods and appropriate regulatory <br /> tests for lime treatment sludges. These data may also be used to compare treatment <br /> operations and to forecast sludge related issues arising at treatment plants. <br /> Sludge sampling <br /> Sludge samples were collected from 11 Canadian mine sites (seven base metal, two <br /> uranium, one gold and one coal) from December 1995 to March 1996. Background <br /> information on AMD production, sludge production and disposal as well as the overall <br /> . treatment process was compiled for all sites. Wherever possible, both fresh (i.e., end <br /> of pipe) and aged (i.e., pond core samples at depth) sludge samples were collected to <br /> http://mend2000.nrcan.gc.ca/reports/3422es_e.htm 1/18/99 <br />