Complex of methodologies and laboratory equipment for determination of coke and slags properties in smelting zone of blast furnace

Abstract

Information about character of burden materials behavior inside a blast furnace at its different horizons enables to increase control efficiency of BF heat running. The elaborated complex of methodologies for carbon materials and iron ore raw materials properties study enables to simulate their behavior at the horizon of iron ore materials reducing, in the viscoplastic zone, at the horizon of iron ore raw materials smelting and its interaction with coke filling. A vertical electric resistance shaft furnace with a tube carbon heater was used as a base equipment for simulation of burden behavior in the reduction zone and smelting zone, as well as for simulation of iron ore burden melt outflow through coke filling. Burden materials preparation to the experiment concluded in crushing of iron ore component followed by 3–5 mm fraction extraction and a mixing it with 3–5 mm fraction of brown coal semi-coke in relation 2:1 for further heating-reduction treatment. The heating-reduction treatment of the mixture charged in the electric furnace simulates the reducing zone and is carried out by a slow heating of the iron ore component and reducing agent mixture from 20 up to 980–1020 ºС. The methodology of determination of lump carbon materials combustibility in the highly heated air blast flow was developed for the complex of equipment based on the shaft electric resistance furnace and aimed at testing of burning process of carbon samples of technological fuels. The combustibility was determined under conditions of burnt sample heating in the temperature range from 500 up to 1500 °C with an accuracy of ±10 °С. The temperature of air blast flow (21 % vol. of oxygen at natural moisture) was set in the range from 120 up to 1200 °С and was kept with an accuracy of ±12 °С. The burnt sample mass, volume of air blast and its velocity was correlated to obtaining of complex non-dimensional Re factor (Reinolds number) more than 100, that guaranteed a reliable process running in the combustion area with no risk of transferring to gasification process. Based on GOST 26517–85 (“Iron ores, sinter and pellets”) a methodology was elaborated for determining of parameters of iron ore materials status in the viscoplastic zone. The methodology comprises heating of preliminary reduced sample of a tested iron ore material in an inert gas and determination of softening temperature and smelting end by a hard rod sinking into the material layer under external pressure action. The temperature at which the layer shrinkage reaches level of 2% during heating, was taken as the softening temperature of the iron ore material. The sinking of the rod into the material by 80% was taken as the temperature of the beginning of the material melting. The interval softening-melting was determined as the difference between melting temperature and softening temperature (at sample shrinkage by 2 %).