In-situ Online Measurement of Rhombic Distortion in Billets
Prabal Patra,
Ashish Tiwari,
Punit Rathore
Issue:
Volume 5, Issue 2, June 2020
Pages:
10-16
Received:
5 July 2019
Accepted:
26 July 2019
Published:
28 May 2020
Abstract: DD (diagonal-difference) is considered as measure of rhombic distortion, aka Rhomboidity, which is a shape related defect in square cross-section billets. Rhomboidity in billets starts with non-uniform shell solidification in the mold primarily due to inconsistent cooling causing irregular heat transfer. The higher diagonal difference greatly impacts the quality of billets to be rolled at various mills. Rhomboidity at or over 4% leads to billet twisting in the roughing stands of the rolling mill. Currently, billet rhomboidity is measured manually at end of casting operation. The presented work describes an optical, online & real-time image processing based method to determine the rhomboidity induced in each strand and alerts the operator to take corrective actions. The online Rhomboidity Measurement System employs sophisticated image acquisition & processing techniques to determine face contours of the billet with sub-pixel accuracy. The key features of RMS are the construction of a gaussian penalty function for selection of suitable 4-lines combination that precisely fits the billet face and use of a highly efficient and accurate statistical indicator, based on KL-Divergence measure, to estimate the rhomboidity even in presence of partial occlusion of billet face by scales. The expected savings are to the tune of 0.27 Million USD.
Abstract: DD (diagonal-difference) is considered as measure of rhombic distortion, aka Rhomboidity, which is a shape related defect in square cross-section billets. Rhomboidity in billets starts with non-uniform shell solidification in the mold primarily due to inconsistent cooling causing irregular heat transfer. The higher diagonal difference greatly impac...
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Structural and Geochemical Characterization of Gold Mineralized Quartz Veins in Belikombone Gold Prospect, Betare-oya Gold District, East Cameroon
Melvin Tamnta Nforba,
Suka Joe Chi,
Tangko Tangko Emmanuel,
Arnaud Patrice Kouske
Issue:
Volume 5, Issue 2, June 2020
Pages:
17-26
Received:
21 August 2019
Accepted:
17 September 2019
Published:
28 May 2020
Abstract: Au-bearing quartz veins in the Belikombone area are confined to major NW-SE orientations in schists and N-S and ENE – WSW in other host rocks. The objectives of this work were to study field, mineralogy and geochemical characteristics of gold mineralised quartz veins. Schists (chlorite rich) and gneisses (moderately magnetic) are the dominant rock types in the area with granite occurring as intrusions within the gneisses. Gold-bearing quartz veins occur in association with metamorphosed rocks ranging in composition from quartz ± gold to those that contain quartz ± gold ± sulphides ± iron-oxides ± sericite and mafic minerals. The mineralized veins contain Au from 0.50 to 25 ppm, while the quartz veins considered barren contain 0.20 ppm Au. The concentration of As in the quartz veins ranges from 0.30ppm to 10.70 ppm and it show positive correlation with Au in samples with high Au concentration. The ΣREE varies from 5.79 to 173.64 in the quartz veins. The investigated veins show evidence of multiphase deformation and it is associated with D2 deformation in the area. This structural setting suggest that the emplacement of gold mineralization occurred during the late Pan African orogeny. The main alteration types are silification, sericitization and sulphidation processes.
Abstract: Au-bearing quartz veins in the Belikombone area are confined to major NW-SE orientations in schists and N-S and ENE – WSW in other host rocks. The objectives of this work were to study field, mineralogy and geochemical characteristics of gold mineralised quartz veins. Schists (chlorite rich) and gneisses (moderately magnetic) are the dominant rock ...
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