Optimization Model of Hot Metal Desulphurization Process in Pansteel
|Keywords||hot metal desulphurization desulfurizer desulphurization slag optimizationmodel|
Desulfurization is the basic requirement and technology of the modern steelmakingprocess. To improve the competitveness and quality of products, iron and steelenterprises increased to research the high value-added of low-sulfur and ultra low-sulfursteel production process. The current blast furnace of Pansteel smelted vanadiumtitanium magnetite with low silicon titanium operation principle, the characteristic ofhot metal containing vanadium titanium was low silicon content and temperature.Due to vanadium extraction technology limited, the production rhythm of hot metaldesulphurization process at Pansteel was tension, and the desulphurization effect wasnot stable when the desulfurization of automatic control model was used, so high unitconsumption of desulfurizer and long desulfurization time, serious iron loss problemwere resulted, and the improvement of production efficiency and automation productionprocess was affected. The process characteristics of hot metal containing V and Tidesulphurization in Pansteel were investigated, the desulfuration feature of magnesiumcompound desulfurizer and calcium compound desulfurizer were studied in this paper.Based on the reaction thermodynamic analysis of hot metal elements and the phasestructure test of slag, influence laws and mechanism of the composition of hot metal andtop slag on desulphurization were studied. Combined with the field actual situation ofinjection desulfurization, contaning characteristics of the desulfurization agents, theinjection process parameters and hot metal conditions of desulfurization process modelwas constructed, and the influence laws of hot metal desulfurization process conditionsand parameters in Pansteel on desulfurization effect were analysed, the optimizedprocess parameters were obtained and applied to the site control model, and achievedgood results. The main research results were as follows:①The deulfurization characteristics of magnesium composite and calciumcomposite desulfurization agents were studied with using the simulation injectionexperiment device and thermal analysis, the injection experiment results were followedthat the desulphurization effect of Magnesium compound desulfurizer was better thanthat of calcium compound desulfurizer, the desulphurization rate was4%5%higherthan calcium compound desulfurizer. The reaction time of two desulfurizers were2025minutes, the unit consumption of desulfurizer should be controlled from6g/kg·Fe to11g/kg·Fe. The total heat changes of hot metal caused by reaction heat effect of Magnesium compound desulfurizer and calcium compound desulfurizer in hot metaldesulphurization were2.64105kJ and9.77105kJ, the temperature of hot metal wereincreased by2.1℃and8.1℃。②The effect of [S],[Si],[Ti] elements in hot metal on desulfurization weresimulate studied with the characteristics of hot metal desulphurization in Pansteel.Thea s,L s, swere improved in the segment of high sulfur （[S]=0.12%0.16%）. Theelement of [Si] in hot metal was played a contradictory role on desulphurization, fsandaswere improved by [Si], but high melting slag shells of2CaO·SiO2or3CaO·SiO2weregenerated by [Si] reacted with CaO of desuiphurization agents, which hindereddesulphurization reaction. The element of [Ti] in hot metal was played an adverse roleon desulphurization, fsand aswere reduced by [Ti], and the high melting CaO·TiO2slagshell hiddered desulphurization reaction.③Based on the composition, phase and structure of top slag on desulfurizationeffect, the research results were as follows that the basicity and w（TiO2） of slag beforedesulphurization had different impacts on hot metal desulphurizaton. When basicitychangeing from0.6to1.2and w（TiO2） changing from12%to24%, thedesulphurization rate was increased with basicity rising, but reduced with w（TiO2） rising.The main phases of powdery slag after deulphurization were CaO and CaS, and themain minerals of spherical slag after desulphurization were2CaO·SiO2, CaO·TiO2,3CaO·Al2O3,2CaO·Al2O3·SiO2,3CaO·MgO·SiO2and Ti（C,N）. Iron phase of slag afterdesulphurization were parceled in CaO·TiO2and TiC, which lead to iron not be broughttogether and settle down.④The process optimization models of magnesium compound desulfurizer andcalcium compound desulfurizer were established with desulfurization theory and sceneprocess. The calculation results were as follow: the powder particle size of twodeulfurizers were0.050.10mm, the injection speed was controlled from50kg/min to60kg/min, and the nozzle depth was4.0m, the effect of desulphurization would be better.After optimization of process parameters using, the unit consumption of desulfurizer inthe low and high sulfur segments were reduced0.86g/kg·Fe and0.92g/kg·Fe, theinjection time of hot metal desulphurization was shorten35minutes.