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Modelling the transport of thiocarbonyl catalysts through a bed of ore Krishnamoorthy, Prashanth

Abstract

Catalytic solutes have been reported to significantly enhance dissolution rates of copper from chalcopyrite. Ethylene thiourea (ETu), a thiocarbonyl compound which has been shown to have such a catalytic effect, is used as a model solute to study the distribution of solute in a column of crushed ore under a point source to simulate the effects of a single drip emitter. To best understand the transport of solutes the transport of water in a column should be quantified first. Using breakthrough curve analysis and a 2-D axisymmetric model for water transport the hydrology parameters are estimated and validated. Further, steady state infiltration tests of ETu solution are performed to generate ETu breakthrough curves which are compared with curves from metal ions such as copper and lithium to estimate solute transport properties such as adsorption and reaction. In the case of adsorption, the Redlich-Peterson isotherm is used successfully to describe the adsorption behavior of ETu in a column of crushed ore. Further, the kinetics of homogeneous reactions of ETu with other solutes in the leaching solution such as Cu²⁺, Fe³⁺ and O₂ are estimated by analyzing the sensitivity of model breakthrough curves and comparing them to experimental results. Thus, a parameterized model for ETu transport though a bed of ore is obtained which is used to estimate ETu breakthrough curves resulting from varying input concentrations, column heights and infiltration rates. The catalytic effect of ETu in the leaching of copper from chalcopyrite ore is analyzed from the perspective of the amount of ETu used to achieve the outcome defined as consumption index (CI). The apparent increase of copper extraction resulting from the doubling the feed concentration of ETu was found to be less efficient than doubling the irrigation flux with half the ETu concentration. Thus, the model is useful tool in providing insight and run what-if scenarios.

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