Kolbin N. Rational cjnditions of iron-ore pellets metallization at reduction by gas in layer conditions

Dissertation is devoted to the investigation of processes occure during the indirect reduction of iron-ore pellet in layer condition. On the grounds of thermodynamic and stochiometric calculations the structure of reducion process in the layer was determined. The reduction zones arising in the layer at reduction by hydrogen were determined and three temperature areas in the range of 500-1100°C were found, which differ by the quantity and kind of reaction zones, as well as the limiting link of the reduction process in the layer. The methodology for investigation of processes occur in the layer at reduction by gas. It makes possible to detailize of reduction process along the layer height. The experimental data that confirm the correctness of theoretical calculation were received. Experiments on studying of technology factors effect on parameters of reaction zones were made. It is received for one type of ferrous pellet, that the speed of reaction zones movement along a layer height is uniquely determined by speed of a supply and equilibrium characteristics of reduction gas. The equation for calculation of speed of reaction zone progress was developed. Research of reduction gas consumption effect on temperature and dimensions of reaction zone was carried out. The analytic formula allowing calculating of reaction zone dimensions was constructed. Data were received by complete factorial mathematic model are in good coincidence with experimental ones. The experiments serie allowing to estimate of changes of ferrous pellet durability on layer height of reduction process. It is shown, that change of durability and volume of pellets are in antibasis dependence. The connection of volume changes and reduction degree of the pellets was shown. It is proved by calculation ther are variuos value of static loads depend of type of pellets laying in the layer. The dependence of static load from layer height was found. Static loadings arising in the layer are not great, and pellets durability is defined not by initial strenght of pellets but by processes occurу at reduction. Key word: reduction, layer structure, linear layer, reaction zone, parameters of reaction zone, strenght, volume change, static load, mathematic model.