Abstract: Low permeability coefficient is one of the main problems in dump leaching in China, and fine content and compactness are the important factors influencing the permeability coefficient of a dump site. Laboratory tests were made to study the permeability coefficient of samples at different fine contents and compaction conditions and to study theoretically the compaction and crushing effect of mechanical compaction on the leaching dump. The results show that with the fine content increasing from 10% to 35%, the permeability coefficient of the sample was decreased by one order of magnitude and the sample was turned from a permeable layer into a semi-permeable layer. With the increase of the compactness, the permeability coefficient was rapidly reduced. Under the test conditions, when the compactness is 84.74%, the permeability coefficient of the sample is only 4.49% of that at its natural state. Therefore, the improvement of stacking technology for reducing the mechanical compaction is an effective way to raise the permeability coefficient of the dump leaching pile.

Key words: Mechanical compaction, Dump site, Dump leaching, Permeability coefficient