Sharandin K.M. Development and implementation of a resource-saving technology for increasing the stability of the converter lining using magnesium materials based on domestic raw materials
The thesis for the degree of Doctor of Philosophy (Ph.D) by specialty 05.16.02 - "Metallurgy of ferrous and non-ferrous metals and special alloys". Institute of industrial and business technologies Ukrainian state university of science and technologies, Dnipro, 2024.
The dissertation work is devoted to the study and development of scientific ideas about the features of BOF process under the condition of periodic application of slag splashing on the working layer of the lining, the dynamics of the formation of working skull based on magnesite waste, as well as periodic hot repair with self-flowing magnesium masses.
The work is a complex study based on the use of developed unique methods of physical modeling and modern methods of mathematical modeling. The adequacy of the created models is confirmed by the correlation of the results of mathematical, physical modeling and theoretical studies with industrial experiments of applying slag splashing technology and hot repair the places of local wear of the converter lining.
It was established that with an increase in the amount of dispersed solid (insoluble) phase in the slag, its viscosity increases. When a concentration of 7-9% of the "grain" phase is reached, the slag has a "satisfactory" viscosity for the splashing operation. And with an increase in the number of "grains" up to 10% or more, a sharp increase in viscosity is observed due to intense heterogenization of the melt.
For the first time, a conceptual approach to the chemical and granulometric parameters of the modifiers was formulated, allowing to provide purposeful management of the physical and chemical properties of the final converter slag. The presence of poorly soluble components in the magnesium briquette in the amount of 60 - 65% (by weight), of which at least 80% have a fraction of 2-6 mm, provide the necessary volume of "grain" filler and the formation of the reinforcing "skeleton" in the cooled skull. At the same time, the easily soluble, finely dispersed, magnesium component, taken in the amount of 40-45% (by mass), saturates the slag with magnesium oxide to the level of 7-8%, already in the first seconds of the splashing process.
The recommendations proposed and implemented in the technological process regarding the selection of fluxes for the formation of skull for applying to the working surface of the converter lining and the parameters of applying the skull, as well as the selection of flux components, including from waste magnesium products, are of practical importance.
The use of the developed fluxes makes it possible to increase the stability of the converter lining, minimize the specific costs of imported refractories based on magnesite, and also increase the performance of the converter.
The developed technological recommendations provide an increase in the stability of the working layer of the converter lining and, accordingly, reduce the specific consumption of refractories by an average of 1.2 - 3.5 kg/t of steel.
The recommendations proposed and implemented in the technological process regarding the selection of magnesium, self-flowing hot repair masses for local wear of the converter lining are of practical importance.
The use of developed domestic self-spreading compounds allows almost completely minimizing the dependence of enterprises on imported analogues, increasing the stability of the lining of units and their productivity, as well as reducing the specific consumption of refractories by 0.003 - 0.01 kg/ton of steel.
Key words: BOF, refractory lining, local wear, hot repair, slag splashing, magnesium flux modifiers, self-flowing hot repair mass, specific costs.
