Research into percolation leaching of copper and silver from aged tailings

Abstract

This paper investigates the extraction of silver by percolation leaching of a pelletized sample of aged tailings with organic binder Alcotac® CB6. Laboratory studies of percolation leaching were conducted using a column with a height of 0.5 m and an internal diameter of 56 mm. Pelletization was performed in a drum-type pelletizer with the consumption of Alcotac® CB6 (BASF, Germany) of 800 g/t and the pellet moisture content of 8–10% and size of 8–10 mm. The sample composition was analyzed taking into account the data obtained by optical tests, electron microscopy, X-ray diffraction, local X-ray spectrometry, X-ray fluorescence analysis, and inductively coupled plasma mass spectrometry. The research object was aged tailings of the Zhezkazgan processing plant (Ulytau region, the Republic of Kazakhstan), where copper is mostly represented by oxidized minerals (78.47%) and sulfide minerals (21.53%). The results of physical and chemical analyses conducted to determine the material composition of samples are presented, along with observations over percolation leaching of copper and silver from Zhezkazgan aged tailings. The copper leaching studies included two stages using a sulfuric acid solution as a solvent. The subsequent stage was silver dissolution by cyanide leaching. Copper extraction into the solution comprised 88.55% with a sulfuric acid consumption of 80.0 kg/t; silver extraction comprised 75.31% with a sodium cyanide consumption of 0.55 kg/t. The conducted studies showed the efficiency of using Alcotac® CB6 for percolation leaching of pre-pelletized aged tailings. During leaching, the pelletized material exhibits sufficient porosity and permeability, thus providing access of cyanic solutions to the surface of precious metals.