RESEARCH METHODS OF IRON ORE SINTERS:IMPROVEMENT IN THEIR QUALITY ASSESSMENT

摘要

Iron ore sinters are the main burden of blast furnaces for pig iron production. The evaluationof these agglomerates is very important due to their properties affect indirectly theproductivity and costs of production of the steel industry. In the sintering plants, the standardprocedure of sinter assessment has been carried out by particle size control, bulk chemicalanalyses, tumbler and/or shatter tests and determination of reduction degradation andreducibility indexes. Microscopy techniques have just been applied to characterize sintersproduced in pilot conditions, however, these techniques, the classical ones and the lesstraditional, allow enhancing the industrial sintering process assessment. For investigation ofthe phases, microstructures and fabric, reflected-light and scanning electron microscopy(backscattered electrons images) were used; for microanalytical chemical examination,energy-dispersive X-ray spectrometry; for Kikuchi patterns registers, electron backscatteringdiffraction. In addition to the microscopy techniques, the magnetic behavior was depicted bymeans of magnetic susceptibility measurements. Iron ore sinters are made up by hematite,magnetite, silicoferrite of calcium and aluminium and silicates. These phases develop eitherduring sintering or, in some proportion, represent remnants of ores and fluxes; this is the caseof some hematite and Mg-bearing silicate, respectively. From the magnetic susceptibilityresults, three different behaviors were determined, which are directly related to the magnetiteproportion in the samples. The phase association and proportion, the sintering conditions andthe quality assessment are some features appraised by such procedures, which reveal themagnitude of this proposal in sintering plants.