Basic Research On Granulation Of Stainless Steel AOD Slag By Air Quenching

The output of stainless steel slag in China is increasing day by day,but the effective utilization rate is low because of its easy pulverization characteristics.Therefore,for the sustainable development of the stainless steel industry,stainless steel slag must be effectively treated and used efficiently.Promoting the comprehensive utilization and green development of stainless steel slag can significantly improve the economic benefits of environmental resources,and play an important role in alleviating part of the energy shortage in China and improving the quality of the ecological environment.In this study,AOD stainless steel slag was used as the experimental research object.The viscosity,surface tension and density of the slag before and after modification with different binary basicity were separately measured,and the AOD stainless steel slag was granulated by air quenching to analyze the effect of the composition of the slag and quenching process on slag granulation results.The main conclusions are as follows:Changing the basicity of the slag and adding modifiers will affect the physical parameters of the slag,and then affect the granulation effect of the air-quenched slag.Before and after the modification,the viscosity of the slag gradually decreases and then increases,and surface tension of the slag showed a downward trend and the density of the slag decreased and then gradually increased as the basicity of the slag decreased;correspondingly,the mean diameter of the granulated slag decreased and then gradually increased with the decrease of the basicity of the slag.After modification,the viscosity,surface tension and density of the slag at the same temperature and basicity are all reduced compared to before modification,while the mean diameter of the granulated slag after modification is reduced at the same temperature and basicity compared to before modification,and the granulation rate is slightly improved compared to before modification.The granulation effect of the granulated slag will also change according to the adjustment of the air quenching process parameters.As the temperature of the slag increases,the viscosity and surface tension of the slag under different basicity before and after modification gradually decreases,and the mean diameter and granulation rate of the granulated slag increase.With the increase of flow velocity,the mean diameter of the granulated slag gradually decreases,and the granulation rate first increases and then decreases.As the injection angle decreases,the mean diameter of the granulated slag gradually decreases,and the granulation rate first decreases and then gradually increases.The phase and morphology of the slag samples before and after air quenching are analyzed.The results showed that the main phases of the slag particles after air quenching were bredigite(Ca₇Mg Si₄O₁₆),calcium silicate(Ca₂Si O₄),a small amount of cuspidine(Ca₄Si₂O₇F₂)and periclase(Mg O).As the basicity decreases,the diffraction peak intensity of each crystal phase of the slag particles gradually weakens,the shape of the slag particles gradually changes into a spherical shape,and the color of the slag particles changes from grayish green to dark green.After the modification,the diffraction peak intensity of each crystal phase of the slag particles weakens more obviously.As the slag temperature increases,the crystalline phase content of the granulated slag decreases,and the slag particles are round and uniform in size.As the flow velocity increases,the proportion of cylindrical slag particles increases,and thin strips of slag particles appear.Reducing the injection angle has little effect on the morphology of the slag particles.As the mean diameter of slag decreases,its crystal phase content decreases,and the slag particles gradually become rounder and more uniform in size.