Studies on the Three-Stage Dilute Hydrochloric Acid Oven Leaching of a Low Grade Iron Ore
Abstract
Iron ore for use in the blast furnace are required to contain at least 63% Fe. The -63 µm fraction of Itakpe iron ore having 34.70% Fe was leached with dilute hydrochloric acid in single and multiple stages (with intermediate water washing) in the sequences H2O-HCl-H2O and HCl-H2O-H2O. The ore as-received and as-leached were also subjected to X-ray fluorescence analysis, while the efficiency of the concentration process was evaluated semi-quantitatively and quantitatively by weight loss % and changes in the chemical compositions obtained. The results obtained showed that the three-stage leaching of the iron ore in the sequence H2O-HCl-H2O at 0.375M dilute hydrochloric acid concentration produced the highest weight loss and yielded iron ore concentrate with 64.5% Fe, indicating a 85.9% upgrading of the Fe content. Similarly, the Si, Al, Ti, Ca, Na, Mg, K and P were reduced by 66.7, 75.8, 40, 96.6, 89.7, 90.1, 89.1 and 94.7 percents, respectively. The Fe content of the concentrate exceeds the 63% specification for the blast furnace use and is only 2.5% below the 67% required for Midrex direct reduction process. The very high reductions in the alkali oxides, phosphorous/sulphur are significant because of their negative roles in iron and steel making.
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