Dephosphorization Research Of Baotou Converter Slag By Microwave Heating And Carbon Thermal Reduction

In recent years, with the rapid development of China’s iron and steel industry and the rapidrise of steel production, the steel-making slag has increased dramatically. Converter slag is akind of by product, which is difficult to deal with than blast furnace slag. Withoutcomprehensive utilization, large amounts of steel slag not only take a lot of land but also pollutethe soil, water, air, and even threaten human’s health. The fact that new slag is growingcontinuously when the old slag is not available has been affecting sustainable development ofiron and steel industry in China even in world. So the comprehensive utilization of steel slag hasbecome a priority in the utilization of byproducts of iron and steel industry. This paper usesmicrowave technology to make the converter slag carbothermal reduction, and studied on thedephosphorization thermodynamics and kinetics and the effect on dephosphorization and underdifferentconditions. Thisthesisconsistsofthreeparts:Using the thermodynamic software Factsage6.2, the reaction thermodynamics ofdephosphorizatio:5C+Ca3(PO4)2=3CaO+1/2P4+5CO is calculated under the condition ofwhether adding SiO2.The minimum reaction temperature and the Gibbs free energy under thecondition of different pressure are calculated. The reaction is identified as the endothermicreaction and the urodynamic conditions of dephosphorization reaction are found. The resultsshow that under microwave heating of the field, the temperature setting in1100~1350℃, thevacuum degree under0.01atm, the reaction of gasification dephosphorization can be smoothrealizationand it’s solid-solidphasereaction.On the basis of thermodynamic calculation, steel slag dephosphorization is studied underthe different carbon equivalent, soaking time, granularity, temperature, pressure conditions. Theresults show that the dephosphorization rate increased with the increase of temperature. Thefirst steelmaking slag as briquetting,the vacuum degree under0.01atm, at a temperature of1100℃dephosphorization rate is up to31%and at1350℃the dephosphorization rate increasedto35.68%. The dephosphorization rate increases with the increasing of carbon equivalent. Withtheincreaseofratio ofcarbonequivalent, dephosphorusfirst increased, thendecreased, thereis a peak dephosphorus rate, show that there is an optimum ratio of carbon equivalent; Thefirst steelmaking slag as briquetting,the vacuum degree under0.01atm, the carbon equivalent is2~3times, dephosphorus rate is higher, about34%;The low granularity, low pressure,increasing holding time are conducive to the reduction reaction and dephosphorization rate. Atparticle size of0.075mm,3Ceq, temperature1300C, holding30mints,the vacuum degreeunder0.01atm and the dephosphorization rate of the first steelmaking slag could up to34.31%.And take the pressure, powdery of converter steel slag block two (under the sameconditionas a steelslag tested).On the basis of thermodynamic calculation, kinetic experiments of dephosphorizationreaction are conducted. To analysis the experimental data, the fact that the dephosphorizationreaction is two order reactions is found and the reaction activation energy is55.516KJ/mol.Therefore,therestrictiveaspectsofthis reactionarethechemical reactioninterface.The results of this paper can provide theoretical guidance for the converter slag recyclingutilizationandachievingzero emissionsofbyproduct.