Ingeniero

BEHAVIOR OF THE PELLETS REDUCTION USING COAL AS A REDUCING AGENT

Sandra Patricia Pérez Velásquez.[1]
Alfonso López Díaz1.

ABSTRACT

The obtaining of steel is made from the iron mineral or from the scrap iron. In the first case, the process takes place via high furnace - converter, in the second one, via electrical arc furnace. Nevertheless, it is also possible to load the electricalfurnace with the pre-reduced pellets of iron minerals, metallic materials that can be obtained from fines of iron mineral (which carries the metallic load), fines of coal (reducing agent), fines of lime (desulphurization agent) and bentonite (coal binder), which take the form of a ovoid by using a pelletizer disc. This project shows the characterization made to the raw materials, the conductedtests of reducibility to pellets loaded in a Furnace Linder type, made from two Colombian iron mineral deposits and the design and construction of a Furnace to evaluate the behavior of pellets during the reduction. It also describes the equipment and it analyzes its results, which permits to observe, that indeed, the studied pellets of iron minerals can be pre-reduced, getting metallization ranks ofaround 84% to 90%.



KEY WORDS

Scrap Iron, Iron and Steel Industry, Iron Mineral, Pre-reduced, Direct Reduction.



COMPORTAMIENTO DE LA REDUCCIÓN DE PELETS
UTILIZANDO CARBÓN COMO AGENTE REDUCTOR



Sandra Patricia Pérez Velásquez.1
Alfonso López Díaz1.
RESUMEN

La obtención del acero se realiza, a partir del mineral de hierro o de la chatarra. En el primer caso el procesotiene lugar vía alto horno - convertidor, en el segundo vía homo eléctrico de arco. Sin embargo, al horno eléctrico se pueden cargar, también, los denominados pelets prerreducidos de minerales de hierro, materiales metálicos que pueden ser obtenidos a partir de finos de mineral de hierro (portador de la carga metálica), finos de carbón (agente reductor), finos de cal (agente desulfurante) y bentonita(aglomerante), los cuales toman una forma ovoide mediante el empleo de un disco peletizador. El trabajo muestra la caracterización realizada a las materias primas utilizadas, los ensayos de reducibilidad efectuados a pelets cargados en un Horno tipo Linder, fabricados a partir de dos yacimientos de minerales de hierro colombianos y el diseño y construcción de un Horno para evaluar elcomportamiento de los pelets durante la reducción. Describe los equipos y analiza sus resultados, que dejan ver que efectivamente los pelets de minerales de hierro estudiados pueden ser prerreducidos, obteniendo grados de metalización del orden del 84% al 90%.


PALABRAS CLAVES

Chatarra, Siderurgia, Mineral de hierro, Prerreducido, Reducción directa.
1. INTRODUCTION


One of the alternatives tocontrol the price of the scrap iron is to replace it or to replace it partially, giving rise to the processes of direct iron mineral reduction whose product is called “Direct Reduction Iron” (HRD) or (DRI) [1]. This project is oriented to the obtaining of pre-reduced pellets, with the purpose of using the fines that are generated in the operation and transportation as well as in the mineralpreparation, and which are unusable at the present time [2]. The development of the processes of iron direct mineral reduction in the world has had a permanent increase replacing gradually the processes of cast iron production in the high furnace because some reactors of relatively small sizes and low cost are used; and in addition, it does not require coke industries, expensive factories, and even, moredemanding features from the environmental point of view.


In this project the characterization of each one of iron minerals is described, which is the object of study, in front of the reduction process, as well as the one of the coal, lime, bentonite, and the process of pelletization of the raw material. Later, the degree of pellets reduction is analyzed guaranteeing their good performance...