Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 3. The picture of bath blowing at application two-level oxygen lances

Further increase of resources- and energy-saving efficiency of BOF processes is unthinkable without development of new methods of blowing and designs of blowing devices. It requires information on the real physicochemical phenomena in the converter cavity accompanying the blowing of the converter bath using new designs of oxygen lances in order to assess the possible risks in the mastering of the proposed developments in industrial conditions. The paper presents the results of video filming of the top blowing of a 80-kg converter bath by groups of multi-pulse supersonic and sonic oxygen jets formed, respectively, by Laval and cylindrical two-level nozzles of two designs equipped with double-row tips with a circular arrangement of Laval nozzles and cylindrical ones and upper block with cylindrical nozzles. Previously unknown information was obtained on the picture of the bath blowing with the formation of a reaction zone of interaction of supersonic and sonic oxygen jets with a metal melt with a flow of carbon monoxide going out the bath and afterburning of CO to CO2 under conditions of a counter-directed double curtain of sonic oxygen jets at different levels of location of the foamed slag-metal emulsions. It was established that in the initial period of blowing during slag formation most of the thermal energy of CO to CO2 combustion flares is transferred to the surface of the bath with lumps of added lime, and the rest is transferred by forced convection to the converter walls and gases escaping from the bath to the neck. In the case of the location of the foamed slag level at the upper tier of the cylindrical nozzles of the lance, heat transfer from high-temperature flares of localized afterburning of CO to CO2 within a limited in size near-lance flow of exhaust gases from the reaction zone is carried out according to the laws of submerged combustion and is completed completely in foamed slag-metal emulsion with the prevention of aggressive action of afterburning flares and volumes of overheated slag on the converter lining. Revealed and recorded by video recording modes of blowing the converter bath, contributing to the development of such undesirable phenomena during smelting as the appearance of intense emissions of slag-metal suspension from the facility, coagulation of the slag with the cessation of dephosphorization of the metal melt, the development of intense dust formation and the removal of small metal particles and slag with the formation of crust on the lance barrel. A variant of the final stage of blowing with a transition to supplying nitrogen instead of oxygen through cylindrical nozzles of two-level lances was experimentally tested, which provides an effective reduction in the level of foamed slag-metal emulsion before the converter turning down. The data obtained were used in the development of an industrial design of a two-level lance with a double-row tip, blowing and slag modes of blowing a converter bath with its use.

Selection of a rational formulation of lightened concretes on combined aggregates

In the difficult conditions of modern construction, the use of concretes with a combined aggregate, if the composition is rational and the formulation and technological factors act rationally, will allow solving many existing problems. In this paper, studies were carried out on the choice of a rational formulation of lightened concrete based on foamed slag, natural crushed stone and granulated blast furnace slag by varying the volume content of a porous coarse aggregate and a fine aggregate in relation to the volume of the mixture. In total, 9 series of prototypes and 1 series of control samples were manufactured and tested. One series of samples includes three cubes with dimensions of 10x10x10 cm. All samples are tested for density, compressive strength and the coefficient of constructional quality. According to the results of the study, it was concluded that the introduction of foamed slag into the composition of heavy concrete instead of a part of a dense coarse aggregate and the replacement of a fine dense aggregate with granulated blast furnace slag leads to an increase in the coefficient of constructional quality, that is, the decrease in compressive strength of concrete is compensated by an even more significant decrease in the density of the material, and therefore a decrease in mass. The increase in the coefficient of constructional quality of concrete based on foamed slag, natural crushed stone and granulated blast furnace slag in comparison with the control composition was 14%.

Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 1. Facility and methodology of the study

Interaction of the upper oxygen jets with the BOF bath considerably effects the hot metal refining flow. To optimize the lances designs and methods of BOF bath blowing, information is needed on the actual physical and technical phenomena taking place during top blowing of BOF bath by groups of ultrasonic and sonic oxygen jets. It was shown that obtaining the information is possible at high temperature simulation of the BOF bath blowing by application oxygen lances of various designs and video registration. Results of previous studies by filming of the blowing in a BOF and OHF presented. Description of modern facilities of high temperature simulation within a multi-purpose 160 and 60‒80 kg BOFs, equipped by special manholes for observation and registration by video camera the physicochemical processes taking place on the surface of the bath presented. In particular the manholes made it possible to observe the processes taking place at various methods of top and combined blowing of the BOF bath by application regular, two-circuit and double-flow oxygen lances. A methodology of test heats carrying out presented, which ensured obtaining important practical information on forming and variation of dimensions of the reaction zone. In particular, information was obtained about the interaction of ultrasonic and sonic oxygen jets with the metal melt, development of afterburning, emission out of reaction zone C to CO2 in the subsonic and sonic oxygen jets with forming high temperature flares directed on the BOF bath surface or penetrated in the foamed slag, emissions of slag-metal suspension out the BOF, forming of metal-slag sculls on the lance tube during the blowing with various level of foamed slag-metal emulsion.

Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 2. The picture of bath blowing at application two-circuit lances

To elaborate blowing and slag modes, a clear picture of BOF bath blowing in various periods of heat is needed. It can be obtained by video registration of physicochemical processes in a BOF cavity. Results of video filming of BOF bath blowing with application two-circuit oxygen lances of five designs presented. Reliable information was obtained on rational form of organization of reaction zone of interaction of ultrasonic and sonic oxygen jets with BOF bath. The picture of physicochemical processes within the reaction zone of interaction of oxygen jets with metal, slag and gas phases of the cavity, preceded to a stable “ignition” of a heat and in the process of the whole heat. A possibility was revealed to accelerate the processes of lime dissolving and slag formation and phosphor removal intensification. The intensification can be accomplished by increase of the number of reaction zones of interaction of ultrasonic and sonic oxygen jets on bath surface and forming of foamed slag-metal emulsion, being stable within the basic part of blowing time. It was shown that at initial period of a heat, it is necessary to ensure consolidation of supersonic oxygen jets, coming out of different reaction zones of interaction. It will enable to oncoming jets to create a curtain on the way of metal and slag drops taking away, to form a flare of CO afterburning to CO2 and ensure heat energy transfer from them to mainly the bath surface. It was established that at the location of the foamed slag-metal emulsion level higher the head end of the lance, the high-temperature products of CO to CO2 afterburning reaction transfer the heat of CO surrounding macro bubble to the shell of slag-metal emulsion. An additional control effect of “hard” supersonic oxygen jets on the bath was also established when replacing the subsonic and sonic oxygen jets by nitrogen ones. At that the flow rate of nitrogen should be big enough to prevent the sealing of cylinder nozzles of the lance head by metal and slag drops during final stage of blowing. The variant of the final stage of blowing was checked experimentally by transfer to the “hard” supersonic oxygen blow, contributing to final metal and slag oxidation decrease.

Research Concerning Reducing the Polluation Degrees in the Sectors of Production of Metal Materials

This paper contains the results of researches and experimentations on the reduction of the concentration of gaseous emissions and powders in the manufacture of ferrous alloys in aggregates of electric arc furnaces (EBT) coupled with a treatment plant (LF) located at Mechel Targoviste using new technology. Experiments have shown that using the new technology one achieves a reduction in pollutant gaseous emissions by about 30% and in dust content by about 25% compared to the use of classical technology, with particularly beneficial effects on the environment. The results have confirmed the validity of the new technology that used iron sponge in the loading phase, foamed slag in the melting phase and long electric arc in the production phase. The paper presents the results of the experiments using both technologies, as well as the equipment established and used in the experiments for the measurement and recording of the gaseous emissions and powders content, which ensured an accurate evaluation of the obtained results.

Investigation of the Raw Materials' Composition and Ratio Influence on the Structure and Properties of the Foamed Slag Glass

The composition of the foam glass based on thermal power plant’s ash-slag waste – foamed slag glass – was developed. The synthesis of the samples based on the most widespread foaming agents was conducted at various temperatures. The structure and properties of the obtained samples were defined, the relationship between the type and amount of the introduced foaming agents and changes in the structure and properties of the samples were established. The best type of foaming agent for the synthesis of foamed slag glass has been selected. The production technology for products based on foamed slag glass was developed.