Abstract
Leaching of iron from ilmenite ore using a binary solution (HCl-NaNO3) was investigated. The raw ilmenite ore sample was characterized using Scanning Electron Microscopy (SEM), X-ray diffraction spectroscopy (XRD) and X-ray Flourescence (XRF) techniques. The influence of acid concentration, oxidant concentration, particle size, solution temperature, stirring speed and liquid-to-solid ratios on the extent of dissolution was examined. The experimental data obtained at various process parameter conditions were tested in six kinetics models: shrinking core model’s diffusion through liquid film model(DTLF), diffusion through product layer model (DTPL), surface chemical reaction model (SCR)); mixed kinetics model (MKM), Jander (three dimensional) model and Kröger and Ziegler model. The crystalline morphology of the sample was displayed by the SEM micrograph. XRF result revealed the dominance of titanium and iron in ilmenite while XRD confirmed that ilmenite exist mainly as FeTiO2. The results of the leaching studies showed that ilmenite dissolution in the binary solution increases with increasing acid concentration, oxidant concentration, reaction temperature, stirring speed and liquid-to-solid ratio; while it decreases with particle size. The study showed that 94.77% iron was dissolved by 1MHCl-0.6M NaNO3 at 75μm particle size, 75˚C reaction temperature, 300rpm stirring speed and 30L/g liquid-to-solid ratio. The kinetics of the leaching process was best described by Kröger and Ziegler model with diffusion through the product layer as rate controlling step. The activation energy, Ea, was calculated to be 6.42kJ/mol. The results indicate that HCl-NaNO3 binary solution can be used as an effective lixiviant for extracting iron from ilmenite ores.
Highlights
Ilmenite or Titanic iron ore (FeTiO3), is widespread in igneous rocks as an accessory mineral, but is seldom concentrated or found in large crystals except in pegmatites and large bodies of plutonic rock
From the results presented in this study, the following conclusions can be drawn: 1. The XRF characterization result show the dominance of titanium and iron for Ilmenite from Egon mine in Egon Local Government Area, Nigeria
The dissolution rate of ilmenite in HCl-NaNO3 binary solution is dependent on the process variables
Summary
Ilmenite or Titanic iron ore (FeTiO3), is widespread in igneous rocks as an accessory mineral, but is seldom concentrated or found in large crystals except in pegmatites and large bodies of plutonic rock. The presence of iron poses a challenge in the production of TiO2 pigment from ilmenite ore. Beneficiation of ilmenite into synthetic rutile has drawn the attention of many researchers considering the increasing scarcity of natural rutile. Reference [1] reported that metal production from any metal source, like ore, concentrate, and secondary sources (various industrial wastes containing metals and scrap metals, etc.) is performed by one of the pyrometallurgical and hydrometallurgical methods, or by a combination of them. The increased depletion of high grade ores and timely need for a shift from conventional pyrometallurgy’s high temperature processing have spurred research interest
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