Quantitative Leaching of a Nigerian Iron Ore in Hydrochloric Acid

A study on the quantitative leaching of iron ore in hydrochloric acid solution has been undertaken. The elemental composition of the iron ore was also carried out using ICP-MS technique. The major elements in the iron ore include: Fe(66.7%); Al (0.2%); Si (5.2%); Ti (0.02%) and O (28.0%). Some traces of V, Ni, Zn, Ce, Cr, La, Y and Zr were also found. The effects of contact time, acid concentration, temperature, particle size and, the stirring speed on the dissolution of the iron ore have been investigated. The dissolution rate depends on the hydrogen ion concentration and temperature of the reaction system. The mechanism of dissolution appears to follow an exothermic pathway. The activation energy for the dissolution reaction was 13.63 kJmol About 92% of the total iron in the ore was dissolved within 120 min. by 12M HCl solution and 80C using 0.1mm particle size. The optimum stirring speed was 300rpm. @JASEM Nigeria is one of the richest countries of the world as far as mineral resources are concerned including iron ores. The estimates of workable iron ore deposits stand in excess of 2.5 billion tones most of which belong to hematite, hematite-magnetite, hematitegeothite and siderite-geothite grades are found in Itakpe. However, Agbaja iron ore deposit (proven reserve – 1 billion metric tonnes) is the largest in Nigeria. However, its high phosphorus (1.4 – 2.0%) and how silicon modulus (SiO2/Al2O3 = 0.89) and fine-grained texture constitute a major problem for utilization in the blast furnace or direct reduction process (NMS Proceedings, 1999). Iron is the sixth most abundant element in the universe and the most abundant metal in the earth’s crust after aluminum (Encycl. Americana, 1992). On the surface of the earth, iron occurs native (uncombined with other elements) in very small quantities, but with other elements, it is found in a number of ores which include haematite (Fe2O3), magnetite (Fe2O4), limonite (2Fe2O3.3H2O), goethite (HFeO2), turgite – [Fe4O5(OH)2], siderite (FeCO3), pyrite (FeS2), chalcopyrite (CuFeS2) and iron silicate that may include chloropal (H6Fe2Si3O12.2H2O) (Encycl. Sc. & Tech., 1997). In Nigeria, extensive high grade iron ore deposits are found in Itakpe and Ajabanoko hills between Okene and Lokoja in Kogi State (Min. & Ind. in Nigeria, 1987). A summary of the important iron ore reserves in Nigeria is given in Table 1. Table 1: Estimated Iron Ore Reserves in Mt. (NMS Proceedings, 1999) S/No Location Indicated Inferred 1. Itakpe 95.0 309.9 2. Oshokoshoko 10.0 85.2 3. Ajabanoko 25.0 65.0 4. Agbaja 962.