RECLAMATION OF THE REJECTS OF PRIMARY BALL MILLS IN CONSTRUCTION OF ORE LEACHING HEAP

摘要

Heap leaching of oxide ores is the first step in hydrometallurgical extraction of copper at Sarcheshmeh Copper Complex in which sulfuric acid is distributed over the surface of the heap that dissolves copper to produce pregnant leach solution. The ore heap is constructed from several layers. The bottom layer is made of compacted impermeable clay on which a cushion layer is built Above these layers a liner made of HDPE (high-density polyethylene) is installed and another fine-grained cushion layer is made over this layer. The cushion layers are intended to increase the resistance to sliding of the geomembrane liner. A granular drainage layer and a filter layer are built on these layers and the oxide ore layer is placed on top over which acid solution is distributed. The granular layer also increases the frictional resistance of the cushion layer. In this investigation the rejects of the primary ball mills are tested to survey the possibility of replacement of gravel with these rejects. Wear resistance, uniformity, chemical and mineralogical analysis, solubility in sulfuric acid, density, etc. are measured for both the gravel and the rejects and the results are compared. The results show that the rejects are more suitable than gravel in all the necessary expected specifications. Economical analysis of the project shows a reduction of about two million US dollars in capital costs.