Heap leach modeling employing CFD technology: A ‘process’ heap model

Abstract

Industrial mining through the process of heap leaching of low grade ores can be employed in the extraction of a range of base and precious metals, such as copper, gold, silver, nickel, zinc and uranium. The process involves the percolation of a leaching solution, typically cyanide, sulfuric acid or acidic ferric sulfate, through crushed ore interacting with a range of oxide and sulfide minerals. These systems involve a complex suite of interrelated fluid, gas, thermal and chemical reactions. A comprehensive computational model needs to account for variably saturated liquid and gas flow in porous media together with the transport of many species through a continually growing geometry, plus multi-phase heat and mass transfer arising from a range of phase change and gas–liquid–solid chemical reaction processes. A number of computational modeling tools employing CFD technology have been developed for the analysis of metals recovery through stockpile leaching. This contribution describes some of the technologies developed particularly to address the key challenges of modeling a full scale industrial heap. Specifically, a ‘process’ heap model is detailed which captures all the key phenomena of a full 3D heap but with significantly reduced simulation times, and so enables rapid analysis by engineers in an operating environment for evaluating a range of ‘what if’ scenarios in production planning.