S. Ferreira

Iron ores, fluxes and tuyere injected coals used in the blast furnace

Abstract Iron ores, fluxes and tuyere injected coals used as burden materials in the blast furnace have been characterised by chemical and granulometric analysis, moisture, density and porosity, softening and melting temperatures, reductibility, X-ray diffraction, electronic microscopy and thermoanalysis. Theoretical calculations on the influence of both the chemical composition and ash content of coals on some aspects of the blast furnace operation have been carried out. The combustion behaviour of pulverised coals in a pilot plant equipped with a combustion chamber has been studied to indicate what the behaviour of each type of coal will be, when injected in blast furnace tuyeres.

Relationship between sinter properties and iron ore granulation index

Abstract A range of iron ores were used in varying proportions to prepare 28 different ore mixtures. Each mixture was classified according to its granulation index and sintered in a pilot plant. The resulting sinters were characterised by chemical analysis, degradation during reduction in the blast furnace (reduction degradation index test), cold strength (tumbler test), coke consumption and process productivity. Sinter quality was assessed in relation to the granulation index of the ore mixture.

Racionalización de mezclas de minerales de hierro para la obtención de sinterizados de calidad optima

Various iron ores, fluxes and coke, were used to prepare four ore mixtures with different proportions of these minerals. With each mixtures a series of sinters were produced in the pilot plant. Each one of the sinters was characterised by: chemical and granulometric analysis; degradation test on the sinter during reduction in the blast furnace, (RDI test); cold resistance test, (Tumbler Test); reducibility test; determining of softening and melting temperatures; and the determination of the structure of the sinter by electron microscopy. T he conditions of the mixtures and the operational parameters for obtaining the optimum quality of the sinters were established.

Cinética de carbocloruración de los pentóxidos de tantalio y de niobio

The carbochlorination kinetics of puré Nb205 and Ta205 by gas mixture (C12 + CO + N2) between 380 and 1,000 °C is studied. A calculation of the standard free energy of the carbochlorination reactions is made. A diagram of the phases stability is drawn. The influence of the gas flow, temperature and the pardal pressure of Cl2 and CO at temperatures below 650 °C on the reaction rate is studied. The apparent activation energy is approximately 75 and 110 kJ/mol for Nb2Os and Ta205, respectively. At temperatures above 650 °C the Arrhenius diagram presents an anomaly which may be attributed to the decomposition of the COCl2 formed in situ. The apparent reaction order of the carbochlorination of these oxides against Cl2+CO is approximately 2. The carbochlorination rates of these oxides are much greater than those of chlorination by Cl2 + N2. The carbochlorination kinetics of tin furnace slag leaching concentrates containing tantalum and niobium compounds are also studied and compared with the carbochlorination kinetics of the puré oxides.