Suppression of decarbonization and resource characteristics of carbonated spinel-corundum refractories in steel-ladle lining

Experimental studies of changes in the pore structure and physical and technical properties of carbonated spinel-corundum refractories under different conditions of decarbonization and the formation of a protective regulatory layer on their hot surface, suppressing decarbonization of the refractory material and mass transfer between the lining and the flow of slag melt, are presented. The results of industrial tests of carbonated spinel-corundum refractories in the working layer of the lining of a 400-ton steel-ladle lining, as well as the topography and consumption specific coefficients of refractories for the functional zones of the ladle lining, the amount of refractory destruction products of the lining during its operation are considered.

Migration and Enrichment Behaviors of Ca and Mg Elements during Cooling and Crystallization of Boron-Bearing Titanium Slag Melt

Synthetic rutile was prepared from titanium slag melt with low energy consumption and a small amount of additive (B2O3) in our previous work. The modification mechanism of titanium slag was not clear enough. The migration and enrichment behaviors of Ca and Mg elements during cooling and crystallization of boron-bearing titanium slag melt were characterized by XRF, FESEM, EMPA, and XPS. Results show that when additive (B2O3) is added, Ti elements are migrated and enriched in the area to generate rutile, while Ca, Mg, and B elements are migrated and enriched in another area to generate borate. With the additive (B2O3) amount increased, Ca and Mg element migration is complete and more thorough. Additive (B2O3) promotes rutile formation and inhibits the formation of anosovite during cooling and crystallization of titanium slag melt. With the additive (B2O3) amount increasing from 0% to 6%, the proportion of Ti3+ in the modified titanium slag reduces from 9.15% to 0%, and the proportion of Ti4+ increases from 90.85% to 100% under the same cooling and crystallization condition. The result will lay the foundation for the efficient preparation of synthetic rutile by adding B2O3 to the titanium slag melt.

Strusky z redukční tavby pelosideritové železné rudy realizované na hradě Buchlově (jv. Chřiby) v roce 2019: extrémní variabilita fázového složení a chemismu jednotlivých fází

During experimental smelting of iron in a replica of historical shaft furnace, which was held at the Buchlov Castle in 2019, charcoal and fresh pelosiderite iron ore from the locality Moravany near Kyjov were used. The obtained furnace slag is practically completely formed by glass phase; only rare small domains contain also crystalline phases, whose occurrence is very irregular. A detailed study of chemical composition showed extreme heterogeneity in composition of glass and most crystalline phases. The glass phase contains variable, but often high amounts of Mn, Ca, Mg and sometimes P and/or K. The composition of olivine ranges widely among fayalite, dicalciumsilicate and tephroite (Fa1-91 Fo3-28Te2-45DCS1-52), as well as those of calcic pyroxene (Wo37-60Tsch1-13Ka8-22Fs4-30En14-36). Feldspars showed compositions between orthoclase and anorthite (Or2-82An9-91Ab5-19Cn0-2Slw0-2), which are unknown from natural systems. Minor components include wüstite, melilite (åkermanite with 1 - 6 mol. % gehlenite), leucite, kalsilite, locally also apatite and an unnamed phase with composition close to Ca2Al2Si3O11. The produced metallic iron is also compositionally heterogeneous and rich in phosphorus. The phase composition of slag differs significantly from those of typical iron slags. The reason can be seen in anomalous chemical composition of used ore, in too high temperatures during smelting (phase relations in metallic iron suggest temperatures around 1500 °C) in combination with rapid cooling of the furnace content after finishing of smelting, and probably also higher viscosity of slag melt. Both phase composition of slag as well as chemical composition of individual slag phases and metallic iron are significantly different from those of local historical artefacts from the period of usage of technology of direct production of iron. These findings do not support the idea that local pelosiderite iron ores were used for production of iron already during this early period.

Development of the model complex of the expert system of control and management of the slag mode in modern mixed blast furnace conditions

The aim of the work is to develop physicochemical bases for predicting the technological properties of finite blast furnace slags, algorithmic and software for the subsystem for diagnosing the slag regime of blast furnace smelting. Based on experimental data on the properties of natural finite blast furnace slags, predictive models for calculating the viscosity of the final slag at a temperature of 1400-1550 °C were improved by including in the model structure an integrated slag melt index of the parameter Δe, which reflects the individual effect. Using the integral parameters of the slag melt characterizing the charge state of the system Δe and the structure of the slag ρ, an equation was developed to determine the viscosity of the slag at any temperature corresponding to the slag temperature at the cast iron outlet. As a result of analytical research, a predictive model for determining the enthalpy of slag depending on the integral parameters Δe and ρ and the temperature of the melt has been developed. It is shown that the viscosity characterizes the fluidity of the slag and provides desulfurizing and drainage properties. The calculation of the viscosity for the specified production of pig iron by the chemical composition of the slag is carried out according to the basic model of slag in a conditionally "homogeneous" state and taking into account its heterogeneity. This takes into account the presence of macroheterogeneous inclusions formed when using coke with low strength characteristics and due to incomplete combustion of pulverized coal fuel in the blast furnace. The improved models for evaluating the viscosity and enthalpy of the final slag are software implemented in the new version of the «Slag» system for operational control of the slag mode of blast furnaces in Ukraine. Rapid assessment of the slag mode using the «Slag» system as part of the DCS allows you to effectively and at a modern level solve the problems of optimizing the slag mode and the quality of pig iron in modern conditions of blast furnace smelting.