Quality Assessment and Reserve Estimation of the Egnaeja Iron Ore Deposit, North-Central Nigeria using Integrated Approach

Abstract

Field, Geochemical and Airborne Geophysical data were integrated in mapping the iron ore deposit around Egnaeja and environs. This research aimed at providing detail geological information that would help in the exploitation of the iron ore deposit in the area through the identification of its precise location, determination of its quality and estimation of its probable reserve. From the aeromagnetic data, strong magnetic signatures that are associated with Iron ore mineralization are well-spread within the study area. The SPI depth estimate to the magnetic sources in the area varies between 20 and 100 m. Areas with high magnetic intensity were observed to have high Thorium (Th) and Uranium (U) counts but low Potassium (K) count. Detailed geological mapping carried out indicates that pisolitic and oolithic ironstones outcrop in more than two-thirds of the study area. From field observation, the thickness of the deposits varied between 2 and 16 m with an average of 9 m while the specific gravity varies from 3.13 to 3.97 with an average of 3.54. The overburden thickness varies from 0 to 10m indicating a high possibility of near-surface exploitation of this resource at a profit. Geochemical analyses of twelve representative samples from the study area reported that the percentage of Iron oxide (Fe 2 O 3) in the samples ranges from 89.83 to 96.91% with an average of 93.04% while the phosphorus content varies from 0.53% to 1.75% with an average of 1.208% indicating high-grade iron ore deposit. An inferred reserve estimate of about 250 million tons of mineable ironstone deposit was calculated for the area. Although this inferred reserve of mineable iron ore deposit is quite encouraging, core drilling is recommended to inform adequate modelling of the reserve to make assurance a double sure prior to exploitation.

Analysis of aeromagnetic filtering techniques in locating the primary target in sedimentary terrain: A review

“…The majority of the authors used Geosoft Oasis Montaj commercial software tools to delineate edges of buried magnetic bodies and compute sedimentary thickness from their aeromagnetic data. Some of the tools in this software were applied to the investigation of deep magnetic sources identified in sedimentary terrains [9] to identify long-wavelength signatures on the TMI, while noise or shallow magnetic sources were identified by short-wavelength signatures. AS has been used to delineate the edges of iron ore bodies, near low magnetic latitude, which occasionally renders map analysis more complicated.…”

“…AS has been used to delineate the edges of iron ore bodies, near low magnetic latitude, which occasionally renders map analysis more complicated. The magnetic SPI depth estimates were determined ranging from 20 to 100 m near the surface [9].…”