Hydrogen reduction kinetics of electrometallurgical slime

The interaction of hydrogen with the zinc-containing electrometallurgical slime of the Severstal’ metallurgical works has been studied. The sequence of transformations in the slime heated to 1100°C in hydrogen or air has been established. The experimental and calculated weight losses coincide. Some of the carbonates are shown to decompose in the temperature range 300–700°C, and most iron and zinc oxides are reduced to a metal. In the temperature range 650–850°C, zinc is almost completely sublimated. At temperatures above 800°C, complex oxides are reduced and calcium and magnesium carbonates and sulfates are likely to decompose. Experimental digital data on the zinc sublimation rate are processed by the least squares method with approximating equations used in thermal analysis. The kinetics of nonisothermal zinc sublimation is comprehensively analyzed using a unique procedure developed for taking into account the background of a peak and the effect of accompanying processes. An equation for the calculation of the zinc sublimation rate under experimental conditions (fluidized bed) is given and tested.     

Influence of Oxygen Dissociation on the Oxidation of Iron

Kinetics of the oxidation of iron in fluxes of atomic and molecular oxygen have been studied over a wide temperature range from 573 to 1273 K. The influence of oxygen pre-dissociation on the oxidation rate was found negligible at 573–1073 K. At temperatures above 1073 K, when only FeO is formed, the rate of iron oxidation in atomic oxygen is substantially higher than that in molecular oxygen. Decarburization occurs during the first stage of oxidation of iron containing carbon. The rate of carbon elimination in atomic oxygen exceeds that in molecular oxygen due to the higher chemical potential of atomic gas.     

Synthesis of wideband matching devices using harmonic-mean power conversion coefficient

Analytically strict expressions for calculation of the parameters of elementary two-ports in the (L, C) element basis are obtained in the case of wideband matching of arbitrary immittances of the signal source and the load whose information is used without an approximation error. The efficiency of application of the harmonic-meanpower conversion coefficient in the matching objective functions is demonstrated. Algorithms for optimization of parameters of a matching device comprised of elementary twoports that use the cascade synthesis and the method of reference sections are proposed. Examples of calculation are given.