Experimental Study On Corrosion Mechanism Of Refractory Materials And Lance Materials In The WEEE Smelting Slag

Top blown smelting processes are the promising technology for the treatment of waste electric&electronic equipment（E-scrap）.E-scrap smelting is usually accompanied by the formation of high-Al₂O₃-content slag.However,this slag can cause problems,such as refractory and oxygen lance materials wear and even accelerated failure,which seriously restricts the development of electronic waste top blowing smelting technology.Therefore,it is of great significance to study the corrosion mechanism of lance materials and refractory materials in the E-scrap smelting slag.In this research,the corrosion mechanism of magnesia-chrome and alumina-chrome refractory materials,and the 3 series stainless steel materials in the Fe O_x-Si O₂-Ca O-Al₂O₃ slag was experimentally studied in the range of1300-1400°C,in air(p_O2=2.1×10⁴ Pa)and at p_O2=10^-2Pa.The obtained results show that:（1）Refractory-component dissolution and new phases formation were the major causes of refractory degradation.Adding Cr and Zr content in the refractory material could enhance its stability in the smelting system.The dissolution of the refractory components increased along with both increasing temperature and decreasing Al₂O₃ concentration in the initial slag.When decreasing the p_O2,the dissolution of Mg O and Al₂O₃ into the slag slowed down.New phases such as forsterite,anorthite,and spinel were detected at the interface between the slag and the bulk refractory.The formation of forsterite accelerated the refractory wear,whereas the newly formed（Mg O,Fe O）（Cr₂O₃,Fe₂O₃,Al₂O₃）spinel phase acted as a protective layer against further corrosion.A lower Al₂O₃ concentration in the slag and a higher smelting temperature both densified the formed spinel layer.Additionally,a high oxygen partial pressure was beneficial to the formation of spinel in the magnesia-chrome refractory corrosion experiments.However,a low oxygen partial pressure was favorable for the formation of spinel on the surface of the alumina-chrome refractory materials.（2）The oxidation and dissolution of steel components,and the formation of（Ni,Fe）（Fe,Cr,Al）₂O₄ spinel phases caused steel degradation.Fe and Cr from the stainless steels were firstly oxidized and reacted with the slag components.The newly formed chrome oxide layers protected the stainless steel from further corrosion at high oxygen partial pressures.When the reaction temperature was low,adding some Ti could be a favor to the formation of chrome oxide layer and help protect the inner alloy from further corrosion in a high oxygen partial pressure.Increasing temperature and decreasing oxygen partial pressure decreased the stability of 316L and321 stainless steels,while increasing temperature and oxygen partial pressure decreased the stability of 304 and 310S stainless steels.Increasing Cr and Ni contents in stainless steel could slow down the corrosion process,however adding Mo and Ti could promote the formation of spinel phases and accelerate degradation at high temperature in low p_O2.This study provides useful information for designing refractory materials and optimizing the processing parameters of E-scrap smelting.27 Figures,23 Tables and 124 References...