Effect of briquetted material temperature on strength of hot-briquetted iron

Abstract

In the process of hot-briquetted iron (HBI) transportation and utilization, a secondary oxidation of the reduced iron takes place, resulting in decreasing its metallurgical value. The studies carried our earlier showed, that oxidation intensity of the metal iron depends on the surface of contact of pure iron with the oxygen, that is to a great extent stipulated by the briquette integrity degree. To elaborate methods of the briquettes strength properties increasing, the mechanism of the porous granules plastic deformation was studied. It was determined, that to obtain stronger briquettes, it is necessary to increase the plasticity of the pressed metallized pellets. A possibility to increase the granules plasticity by increasing the material heating degree considered. Results of experiments on porous granules of reduced iron pressing presented, dependence of the granules heating degree on the result of the pressing loading considered. Chemical and the grain-size compositions of the reduced pellets, used in the experiment, quoted. The dependence of the briquettes porosity on the briquetting temperature determined. It was revealed, that at the briquetting temperature 720 о С and higher, due to “plastic flow”, the material consolidation takes place without load, the briquettes porosity decreases and HBI strength is higher 1.2-fold and more, comparing with that of briquettes, obtained at the pressing temperature 680 о С . The tests of the briquettes strength by throwing them down from a height showed, that the briquettes obtained at the briquetting temperature higher 720 о С , were practically solid, only chipping-off of small surface particles was observed.