RESUMO
Dual and multi energy X-ray transmission imaging (DE-/ME-XRT) are powerful tools to acquire quantitative material characteristics of diverse samples without destruction. As those X-ray imaging techniques are based on the projection onto the imaging plane, only two-dimensional data can be obtained. To acquire three-dimensional information and a complete examination on topology and spatial trends of materials, computed tomography (CT) can be used. In combination, these methods may offer a robust non-destructive testing technique for research and industrial applications. For example, the iron ore mining and processing industry requires the ratio of economic iron minerals to siliceous waste material for resource and reserve estimations, and for efficient sorting prior to beneficiation, to avoid equipment destruction due to highly abrasive quartz. While XRT provides information concerning the thickness, areal density and mass fraction of iron and the respective background material, CT may deliver size, distribution and orientation of internal structures. Our study shows that the data provided by XRT and CT is reliable and, together with data processing, can be successfully applied for distinguishing iron oxide rich parts from waste. Furthermore, heavy element bearing minerals such as baryte, uraninite, galena and monazite can be detected.
RESUMO
In iron ore processing plants, different tailing streams are usually transferred to the tailings thickener for partial dewatering and finally transferred to the tailings dam as a single stream. Therefore, the mixing of different tailings streams happens. This way can challenge the process of reprocessing the tailings in the tailings dam since the mixing of different tailings streams causes more complexity in the mineralogical composition as well as the chemical composition of the tailings in the tailings dam. To solve this problem, the idea of separate characterization and separate upgradation of different tailings streams of an iron ore processing plant was carried out and a comparison was made between the results of magnetic upgradation of each tailings streams with the total tailings (i.e., the tailings in the tailings dam, which is a mixture of different tailings streams of the plant). Hence, the different tailings streams of an iron ore processing plant were sampled and characterize for total iron, FeO content, particle size distribution, mineralogical composition by X-ray diffraction (XRD), magnetic behavior by Davis tube tests, and dry solid tonnage rate. The characterization results showed that the iron grade and dominant iron ore mineral vary from one stream to another tailings stream of the iron ore processing plant. For instance, the total iron content of different tailings streams varies in the range of 18.46 to 64.68% and the dominate iron ore mineral in the Cobber tailings was hematite, but in the other tailings streams it was magnetite. The magnetic upgradation of the Cobber and Rougher tailings and also the total tailings were performed separately by the wet magnetic separation at different magnetic field intensities of 2000, 3500, 5000, and 15,000 Gauss. A concentrate with the highest iron grade of 61.79% and yield of 52.15% was produced from magnetic upgradation of the Rougher tailings, but magnetic upgradation of the total tailings produced a concentrate with the iron grade of 37% and yield of 15.2%. A comparison between the magnetic upgradation of the total tailings and the Cobber and Rougher tailings revealed that the upgradation of Rougher tailings results in a concentrate with higher iron grade and yield than the total tailings.