Mathematical modelling of the thermal regime of a ladle- furnace unit considering internal heat sources

We apply mathematical modelling to study heat transfer processes during fire refining of blister copper in a ladle-furnace unit. A ladle-furnace unit was designed to test the refining technology using bottom blowing in a bubble mode by gaseous reducing agents (hydrocarbons) and an oxidiser. Mathematical modelling allows the properties of a real process to be described based on mathematical formalisation of physical laws and regularities. It was proposed to use gaseous reducing agents, rather than expensive residual fuel, as a liquid-reducing agent. The use of gaseous reducing agents in the bottom blowing mode produces higher technical and economic indicators of the process. In addition, some technological operations were transferred directly to the ladle, thereby eliminating the need for re-melting and heating of refined copper. One of the identified problems was the need to maintain the predetermined thermal regime, which provides the very possibility of both performing refining operations and introducing a gaseous reagent (determining the hydro-gas-dynamic parameters) into the melt during bottom blowing. An original method for considering the thermal effects of chemical reactions in mathematical models was presented using an example of exothermic reactions during oxidative refining. The use of two different methods of analysis allowed a comprehensive assessment of the influence of the main exothermic reactions on the thermal regime of the refining process. The presented mathematical models can be used for determining the specific effect of various technological parameters (composition and fuel consumption, temperature and degree of blast enrichment, lining design, etc.) on the dynamics of changes in the temperature field of the melt and the technical and economic parameters of melting as a whole.

Study Results of the Electrical Parameters of the High-Power "Ladle-Furnace" Unit and its Impact on the Power Supply Network

The steel refinement and its chemical composition and temperature finalization processes in a pouring ladle carried out by heating the metal with electric arc have received wide use at modern metallurgical enterprises. The article considers the electrical operating conditions of the ladle furnace unit (LFU) equipped with a 40 MVA electric furnace transformer. It was expected that the LFU load would vary insignificantly, because the electric arc burns between the electrodes and the surface of already molten metal, without the occurrence of short circuits. However, the accomplished studies testify that the LFU load is abruptly variable and nonlinear in nature, and gives rise to significant voltage fluctuations and harmonic distortions in the power supply network. The flicker intensity (severity) factor has been estimated, and the level of current harmonic components generated due to LFU operation has been determined. By using the obtained results, it becomes possible to predict the influence of LFU electric operating conditions on the levels of electric power quality indicators in changing the power supply network parameters, and to adopt circuit engineering solutions for assuring the electric power quality in the plant electric power supply system.

Prospects for the Use of Hollow Electrodes for Deep Desulfurization of Steel in the Ladle-Furnace Unit

The article discusses the possibilities of intensifying the process of desulfurization of molten steel in the process of after-furnace treatment of molten steel in the ladle-kiln unit. As one of the techniques, it was proposed to heat the melt with the help of hollow electrodes with argon feed during the operation of the electric arc plant. Comparative thermal balances of the installation in the basic and experimental versions and on the basis of the proposed mathematical model for calculating the mass-average temperature of the melt are given, and graphs of temperature changes during processing are plotted. To assess the efficiency of the desulfurization process, arrays of heats were processed in the basic and experimental mode and original three-parameter graphs were built, allowing to estimate the degree of desulfurization in both modes as a function of processing parameters.

Energy analysis of an electric furnace with a vibration hearth for roasting vermiculite concentrates

An energy analysis of an electric furnace with a vibration hearth using previously obtained analytical absorption models and a new, refined model of vermiculite heat assimilation is presented. The temperature-time equation, the formulas of the productivity of the furnace unit and the specific energy intensity of the calcination of vermiculite concentrates are obtained. It is shown that the new concept furnaces have a specific energy intensity of not more than 77.8 mJ/m3, which is more than three times lower than the energy intensity of fiery furnaces for roasting vermiculite. Ill. 4. Ref. 14.