Mineralogical Characterization of Dilband Iron Ore Deposits of Balochistan, Pakistan

Abstract

Dilband iron ore deposits, recently discovered in 1997 by Geological Survey of Pakistan (GSP) in Kalat Division Balochistan, Pakistan, is of major importance from a socio-economical point of view among the indigenous iron ore deposits discovered so far in Pakistan. In order to meet the requirements of Pakistan Steel Mills ore specification (i.e. 57–60 % Fe (min), 8.5 % SiO2 (max), 0.5 % Al2O3 (max), 0.1 %P (max), and 0.05 % S), the ore requires an adequate concentration method. This calls for detailed characterization of process relevant minerals and their intergrowth. For this reason mineralogical, petrographic, and elemental analysis were performed using XRD, thin section and SEM with EDS, and XRF and Atomic Absorption Spectrometer techniques, respectively. Mineralogical study revealed that Dilband iron ore is mainly composed of 46.27 % hematite, 17.41 % quartz 14.47 % calcite, 9.24 % chlinochlore, 10.5 % kaolinite, and 1.75 % fluorapatite minerals. Atomic absorption analysis of different size fractions ranging from −600 µm down to −38 µm indicated that Dilband iron ore contains on average of 40.18 % Fe, 18.34 % SiO2, 5.32 % Ca, and 2.262 % Al. Whereas average analysis of different size fractions on XRF indicated 44.3 % Fe, 20.4 % SiO2, 8.8 % CaO, 6.35 % Al2O3, 1.08 % P2O5, and 0.065 % SO3. Three types of iron stones namely hematiteooides, hematite-peloids, and hematite biosparite were identified from petrographic study. From the mineralogical and elemental analysis data finely dissemination of impurities specially quartz, alumina and phosphorous in hematite phase is conceived, suggesting that Dilband iron ore is not amenable to upgrade with conventional techniques.