I. V. Nekrasov

Stabilization of Refining Slag by Adjusting Its Phase Composition and Giving It the Properties of Mineral Binders

Refining slag used in out-of-furnace metal processing units, due to significant content in it of the unstable phase—dicalcium silicate, is prone to decay due to its polymorphous transformations, accompanied by an increase in the volume of the crystal lattice. Getting into cracks of the furnace lining, the slag can cause its destruction. The results of investigating the mechanism of stabilizing the refining slag by introducing alumina flux to it, while giving it the properties of mineral binders, are presented here.

Production of mineral binder from steel-smelting slag

The phase composition of steel-smelting slag may be processed to obtain mineral binder. Gypsumbased binder has been produced on the basis of refining slag from the ladle–furnace unit. Hydraulic-binder clinker may be obtained on the basis of steel-smelting slag. The possibility of processing such slag to obtain mineral binder is demonstrated.

Effect of Refining Slag Phase Composition on Ladle Furnace Unit Lining Life1

The working layer of a ladle furnace unit (LFU) lining made from periclase-graphite refractory is most strongly subjected to the effect of corrosion factors that concern thermal, mechanical, and chemical action. The strongest destructive effect on a lining is the chemical factor. This article provides results of studying the effect slag phase composition on chemical breakdown of a LFU periclase-graphite lining.

Extending the lining life in circulatory vacuum units at OAO EVRAZ NTMK

Practical methods for extending the life of submersible tubes in vacuum chambers are considered. The structure of periclase-chromite components is studied. Refractories corresponding to optimal vacuum-chamber operation in the converter shop at OAO EVRAZ NTMK are selected.

Improving the durability and reliability of vacuum-chamber linings

Several practical methods of improving the durability of vacuum-chamber linings in the converter shop at OAO Nizhnetagil’skii Metallurgicheskii Kombinat are considered.

Assessing the viscosity of industrial slags

Predicting the physicochemical properties of slag is important in order to develop metallurgical technolo� gies. A significant property of slag is its viscosity, since many metallurgical processes depend on heat and mass transfer in slag. In practice, slag is heteroge� neous, as a rule, and therefore the required viscosity is obtained by regulating its composition. For this pur� pose, specialists rely on empirical formulas that only qualitative reflect the process. Difficulties in describ� ing the properties of heterogeneous slag hinder the development and use of reliable quantitative formulas. Obviously, this limits the controllability and efficiency of the technology. The mean chemical composition of heterogeneous slag does not fully characterize its properties. The development of adequate models calls for a method of calculating the phase distribution of the components and the number of phases in the slag. In that case, the effective viscosity could be estimated from the mean chemical composition and temperature on the basis of formulas for the viscosity of suspensions [1]. The possibility of applying a version of the Einstein formula to slag was discussed in [2–4] (1)

Influence of intensified electrosmelting on the lining life of the DSP-135 arc furnace at OAO Severskii Trubnyi Zavod

The wear topography of the lining of the DSP-135 arc furnace at OAO Severskii Trubnyi Zavod is analyzed. The difference in effectiveness of magnesia slag-forming agents in converters and electrofurnaces is discussed. Means of extending the lining life in superpowerful arc furnaces are considered.

Automatic monitoring of slag composition during steel treatment in a Ladle-Furnace unit

847 As metallurgists know, requirements on product quality are high and likely to increase. A complicating factor is that the quality of raw materials is deteriorating. In particular, the content of harmful impurities is increasing, which increases the importance of refining processes in steel smelting. The quality of metal products is largely established in the smelting process and especially in the ladle–furnace unit, where nonmetallic inclusions, sulfur, and oxygen are removed. The effectiveness of these refining processes depends on the oxidizing properties of the refining slag. In practice, optimal slag characteristics cannot always be ensured. Often, the transfer of furnace slag to the ladle means that refining in the ladle–furnace unit begins in the presence of slag containing 3–8% FeO; higher values are also possible. Given the need for appropriate preparation of the steel for continuous casting and for steel quality, the operators of the ladle–furnace unit must take ongoing and judicious action to reduce the refining slag. This calls for timely and precise data regarding the content of ferrous oxide in the ladle slag. The monitoring method used in practice— which involves taking samples, sending them to the laboratory for analysis, and waiting for the results—is unhelpful, on account of its lack of flexibility. Specialists from the Institute of Metallurgy, Ural Branch, Russian Academy of Sciences, and Ural State Technical University–Ural Polytechnic Institute have investigated the possibility of continuous monitoring of the slag composition on the basis of electrical parameters of steel treatment in the ladle–furnace unit and in an ac arc smelting furnace. An electrical parameter that is sensitive to change in slag properties is the constant component of the ac arc voltage ( U cc ). In the present work, we consider the influence of the chemical composition of refining slag on U cc . An important aspect of an ac arc is that the breakdown conditions of the gas gap are not the same in successive half-periods when the cathode is the graphitized electrode or the steel. As a result of the difference in electroemissive properties of the graphitized electrode and the steel, the curves of the arc current and voltage will be asymmetric with respect to the time axis. In the half-period when the metal bath is the cathode, greater voltage is required to maintain the arc current than in the half-period when the graphitized electrode is the cathode. The difference in these voltages results in asymmetry of the voltage curves and the appearance of U cc ; U cc is assumed to be positive in the direction from the electrode to the steel. The following factors permit monitoring of the slag composition on the basis of U cc . Over the period, the ac arc is twice extinguished and reignited [1]. In fact, over the period, there are two different arcs, burning at two different cathodes. Besides the emissivity of the metal, the presence of slag will affect the arc characteristics in the half-period when the steel is the cathode. Therefore, in some way, the slag properties are reflected by the characteristics of the arc discharge in that half-period. The discharge characteristics may be recorded by special apparatus, and the corresponding electrical signals may be converted to information regarding the slag composition, given that the emissive properties of the graphitized electrode and the metal remain practically unchanged in the course of treatment with relatively stable temperature in the ladle–furnace unit. Laboratory and industrial research is conducted to establish the relation between slag composition and U cc . A method of determining the dependence of U cc on the slag’s chemical composition is developed, on special laboratory apparatus (Fig. 1). In a series of experiments, the dependence of U cc on the concentration of some slag components may be determined (Fig. 2). The experiments are conducted in molybdenum crucibles, at an arc voltage of 33 V, constant basicity (1.5) of the three-component slag, and a temperature of 1600 ° C. The content of the third slag components is varied in the experiments by adding a pure component to the CaO– SiO 2 system. The results indicate that different slag components have different effects on U cc : WO 3 , FeO, and MnO increase U cc ; MgO and TiO 2 have practically no influence; V 2 O 5 and Al 2 O 3 reduce U cc . This may be due to the participation of these oxides in arc ignition in the half-period when the metallic bath is the cathode. Literature data show that the arc voltage and current in a specific half-period will be determined by the proAutomatic Monitoring of Slag Composition during Steel Treatment in a Ladle–Furnace Unit

The opportunity of silicate product manufacturing with simultaneous pig iron reduction from slag technogenic formations

There are two main kinds of slag in modern steelmaking industry: the electric arc furnace slag (EAF slag) and ladle furnace slag (LF slag). The all known slag processing schemes provide the iron-containing component reduction while silicate component stays unprocessed. On the contrary, the silicate processing schemes doesn’t provide the utilization of the iron-containing component. The present-day situation doesn’t solve the problem of total slag utilization. The aim of this work is to investigate the opportunity of silicate product obtaining with simultaneous pig iron reduction from EAF and LF slags. The tests are conducted by the method of simplex-lattice design. The test samples are heated and melted under reductive conditions, slowly cooled and then analyzed by XRD methods. The experiment results prove the opportunity: the Portland clinker and pig iron can be simultaneously produced on the basis of these slags with a limestone addition.There are two main kinds of slag in modern steelmaking industry: the electric arc furnace slag (EAF slag) and ladle furnace slag (LF slag). The all known slag processing schemes provide the iron-containing component reduction while silicate component stays unprocessed. On the contrary, the silicate processing schemes doesn’t provide the utilization of the iron-containing component. The present-day situation doesn’t solve the problem of total slag utilization. The aim of this work is to investigate the opportunity of silicate product obtaining with simultaneous pig iron reduction from EAF and LF slags. The tests are conducted by the method of simplex-lattice design. The test samples are heated and melted under reductive conditions, slowly cooled and then analyzed by XRD methods. The experiment results prove the opportunity: the Portland clinker and pig iron can be simultaneously produced on the basis of these slags with a limestone addition.

Stabilization of refining slags by correction of their phase composition

The stabilization of refining slags in ladle treatment with alumina fluxes is studied. In refining, the slag is stabilized in the presence of alumina fluxes thanks to isomorphic replacement of a calcium ion by alkali-metal ions and to decrease in the dicalcium-silicate content in the melt as a result of its replacement by aluminum-bearing phases.