Comparative Kinetics of Iron Ore Dissolution in Aqueous HCl-HNO₃ System

Onyedika Gerald, Nwoko Christopher, Oguarah Ayebatonworio, Ogwuegbu Martin

Mineral Processing Unit, Department of Chemistry, Federal University of Technology, Owerri, Nigeria.

DOI: 10.4236/jmmce.2013.14026                

Abstract

The dissolution kinetics of the dissolution of iron ore in aqueous HCl/HNO3solution was studied. The elemental composition of the ore was carried out using the inductively coupled plasma-optical emission spectrophotometer (ICP-OES). The result showed that the iron ore contain; Fe (62.1%), O (21.7%), Cu (11.1%), Mg (2.39%), Na (1.51%), Mn (1.47%), K (0.78%), Ca (0.58%) and Zn (0.01%). It was determined that the dissolution rate increased with increased solution concentration, temperature, time and decreased particle size of the ore. The optimum conditions for effective dissolution of 88% of the iron ore were found to be 8 Mof the solution, 353 K, 100 min and ore particle size of less than 75 μm. The kinetic evaluation of the dissolution process was studied using three different shrinking core models (SCM); Film diffusion: k_ft =X_B; interfacial chemical reaction k_rt = 1－(1－X_B)^1/3 and ash/product layer diffusion :  for spherical materials was performed. The results obtained showed that the rate determining step for the dissolution process was the product layer diffusion and therefore, the reaction followed this mechanism. The apparent activation energy (Ea) and the order of reaction were found to be 20.48 kJ/mol and 0.7 respectively.

Keywords

Kinetics; Dissolution; Iron Ore; Shrinkage Core Model

Conflicts of Interest

The authors declare no conflicts of interest.

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