Physical and Numerical Modeling of the Slag Splashing Process

The influence of technological factors on the process of slag splashing was analyzed in the paper. The problems were solved in several stages using our own and commercial calculation programs and laboratory tests. Based on the performed calculations and simulations, factors affecting the slag splashing were determined. It was observed that the high efficiency of the process can be achieved by optimizing numerous technological parameters, e.g., flow parameters, pressure, and temperature of the nitrogen stream, height and angle of the lance position, as well as slag height into which the gas stream enters and MgO consumption. In addition, the chemical and mineralogical composition of the slag and its physicochemical parameters should be also considered. The obtained results of numerical simulations of slag splashing in the oxygen converter coincide with the results of experiments carried out using the physical model of oxygen converter. This means that the simulations well represent the real course of the slag splashing process for the studied variants.

The investigation on the middle period dephosphorization in 70t converter

An experimental test is carried out on the 70t converter in Masteel to study the law of middle period dephosphorization in the smelting period. It is found that the dephosphorization rate is slow in the early and middle period of smelting and the content of the final P in steel cannot reach the standard due to the low oxidation of slag. The content of the final P in steel can be controlled within 0.02% by adding ore to the molten bath in the middle period and raising the lance position. The experimental test shows that the dephosphorization can still be achieved by a large margin if appropriate slag conditions are maintained in the middle period when the C and O reactions are strong. By theoretical calculation, it is concluded that the slag content should be controlled between 15 and 23%, and the basicity of slag should be between 2.5 and 2.8 in the middle period of production. Through the observation of experimental slag by SEM, it is found that the limiting factor of dephosphorization in the middle period under the test conditions is that the dephosphorization speed is too slow due to the low oxidation, rather than the solidification of phosphorus.

Study of the interrelations of blowing parameters, options of electric influence and nature of liquid spraying by physical modeling

The main and decisive factor of blowing in oxygen converters is interaction of high-speed oxygen jet with a molten bath. The features of this interaction determine hydrodynamics and level of metal losses with slopping and spitting. Their study is most accessible with cold modeling. The paper presents results of laboratory studies on the physical model of a 160 ton converter manufactured at a scale of 1:30 to study the influence of blowing modes on character of liquid spraying. It is blown through a lance with five nozzle tips at 10 horizons in model height on three zones of working volume of converter model: area near lance, area near the wall and out-of-model area. That in practice corresponds to intensity of formation of skull on the lance, on converter mouth and on elements of the fume gas collecting system. It was found that the total amount of liquid sprays carried out of the model is extreme and depends on level of lance position, with a noticeable decrease in the amount of sprays at zero height above the liquid, and above certain values. The possibility of reducing of the intensity of splashing formation and the level of liquid loss within the investigated zones was determined by applying a low-voltage electric potential: with negative polarity in the area near the lance and near the walls, and with positive polarity – out of the model. It was revealed that beginning of practical influence of the potential and the maximum value of “useful” power allocated in the sublance zone is determined by specific combination of pressure before the nozzle and the level of tip of the lance: the higher the pressure in front of the nozzle is, the higher lance position is needed to reach maximum values of “useful” power. The experiments, conducted on physical model during blowing of saline solutions with gases at using of electric potentials, have shown possibility of extending the scope of developed method to processes not related to metallurgy.

Investigation of electric potential difference during the top oxygen blowing in converter

Purpose: of this paper is to investigate the method of monitoring the course of the main oxidation-reduction processes and dust depression during the top oxygen blowing, based on the registration of natural electric potential difference on the lance-metal melt site during the blowing. Design/methodology/approach: Exchange processes in the converter bath take place with exchange of electrons and ions between metal and slag melts and gas phase. Since the processes are far from equilibrium, if to complete the circuit it will be possible to register the potential difference. Investigation was conducted in industrial converters of 60-t capacity at medium-carbon steel smelting. During the blowing the potential difference in the lancemetal bath site, the position of the lance and the dust level after gas cleaning were recorded. Findings: It was revealed that the level and sign of variation of the potential difference in the lance-metal bath site reflects the course of the main oxidation-reduction processes in the sub lance area during melting periods: oxidation of silicon, carbon and iron. The probable course of gaseous oxygen interaction with the metal fusion was discussed. Practical implications: In order to reduce the dust level without slowing down the carbon oxidation process, it was recommended to place the lance at a level corresponded to the potential difference during the active carbon oxidation period 30 % lower than 200-210 mV. The results of heats, conducted with the proposed mode of lance position, showed that the level of dust emission was 16% lower than on the comparative melting. Originality/value: The level and sign of the potential difference is possible to use to select the lance position during the blowing for longer slag foamed state without overflow that ensures a lower level of dust emission.

Study on Applied Technology with Soft Measurement for Lance Position Based on MLR and PCR

Because the lance position of oxygen-enriched air and top-blown furnace is affected by lance pressure, melt temperature, melt furface,the type of slag and other factors, it is difficult accurately measured. Firstly, processing informations(excluding data,analysis correlation) to the production data.Then identified the main auxiliary variables of soft measurement model and established MLR and PCR soft prediction model of the lance position.Secondly,according to production data,through fitting and forecasting of these models, the results show that the PCR model's forecasting ability is better than the MLR model.Finally, the obtained model is embedded in WinCC software platform and further verify the feasibility of the model.The research may guide the production and lay theoretical foundations for the lance position control

Research on High Efficiency Blowing Technology of 200t BOF

In the early stage of commissioning, in order to solve the problem of bad metallurgical effect and serious lining erosion during steelmaking, oxygen supply strength is improved and lance position is adjusted as well. In addition, technology of “remaining slag and charging dolomitic lime” is applied to reduce the erosion velocity of lining. Results show that metallurgical effect of BOF is better after oxygen supply strength is improved, and which ensure the high efficiency production and smooth operation of BOF.