A Comparative Study of Tailings Analysis Using Acid/Base Accounting, Cells, Columns and Soxhlets

Abstract

The overburden analytical techniques involving acid/base accounting, weathering cells, columns and soxhlet reactors were tested and compared using several tailings samples having a variety of NPIS ratios. Tailings were used to normalize the effect that particle size has on leachate quality and were characterized by acid/base accounting data. The results showed that samples with high NP's and high S percentage gave similar results in all testing procedures. For the weathering cells and soxhlet tests it was shown that the leaching technique, in addition to producing a unique quality leachate, modified the sample chemistry that caused shifts in acid/alkaline production. The fine-grained nature of the tailings afforded high specific retention of fluid, creating airlocks within the columns that skewed the results. When the leachate quality predicted and obtained by the various tests was compared to the actual drainage quality emanating from the sites from which the samples were collected, the least accurate were the column tests, next were the acid/base accounting projections, then the soxhlets, with the weathering cell tests being most accurate. Additional Key Words: Acid mine drainage, overburden analyses, mine drainage quality prediction.