A comparative analysis of the dissolution kinetics of lead from low grade oxide ores in HCl, H₂SO₄, HNO₃and citric acid solutions

A comprehensive study of the leaching behavior and dissolution kinetics of copper oxide ore in sulfuric acid lixiviant

“…In heterogeneous reaction systems, most reactions follow a shrinking core model (SCM) which approximates the dissolution of real particles [31]. According to this model, it can be concluded that the leaching process in H 2 SO 4 solution involves: (i) transport of H 2 SO 4 from the bulk solution to the particle surface, (ii) diffusion of H 2 SO 4 through the solid residual layer from the particle surface to the surface of unreacted core, (iii) reaction between H 2 SO 4 and oxide ore on the surface of the unreacted core, (iv) diffusion of the resultants through the solid residual layer from the reaction interface to the particle surface, and (v) transport of the resultants from the particle surface to the bulk solution [28,29,32]. Generally, this model expressed by below described equations [11,19,31].…”

“…A 5 mL samples were accurately withdrawn at regular intervals during the reaction and were immediately filtered. Then the solution was analyzed using a unicam atomic absorption spectrometry (AAS) [28,29]. The amounts of copper leached was calculated via the following equation:…”

Modelling of Lead Corrosion in Contact with an Anaerobic HCl Solution, Influence of the Corrosion Product Presence

“…During the dissolution, Azizi et al showed that three steps are considered to occur in succession: (1) transport of the reactant through the solution to the surface of the solid (H + , anions), (2) reaction on the surface between the reactant and the solid, and (3) formation of the products on the surface layer of the reaction zone and their transport from the interface into the bulk of solution [21]. Moreover, when HCl was used as a leaching reagent, the leaching rate of lead in the HCl solution is not only a diffusioncontrolled process or only a chemically controlled process; rather, both processes of the fluid film diffusion and chemical reaction act as a rate-controlling step [13,21]. A dependence on temperature is shown by Baba et al, who suggested a diffusion control mechanism at lower temperatures and a surface chemical reaction controlled mechanism at higher temperatures [22].…”