Study On The Occurrence State And Distribution Behavior Of Chromium In The Preparation Of Chromium Containing Glass Ceramics

Stainless steel slag is a toxic waste containing heavy metal chromium.At present,its harmless utilization is the bottleneck of the sustainable development of stainless steel industry,and also a worldwide problem.The results show that chromium is the most stable in the form of spinel,at the same time,as the crystal nucleus of the nucleation stage of glass ceramics,chromite spinel can promote the precipitation of diopside phase,Using stainless steel slag to make glass ceramics is an effective way to realize its harmless and high value utilization.In view of the lack of research on the effective control of chromium spinel nucleation in the nucleation stage and the migration and distribution of chromium elements in the nucleation and crystallization process in the preparation of microcrystalline glass at present,this paper focuses on the influence of basic glass components on the formation of chromium spinel in the nucleation stage and the migration and distribution of chromium elements in the crystallization process.The research result is to realize the innocuity of chromium containing stainless steel slag and high value reuse provides experimental data and theoretical basis,which has positive economic and theoretical significance.The main research contents are as follows:In this paper,the suitable composition range is found by the calculation of thermodynamic factage 7.1 and the phase diagram of CaO-MgO-Al₂O₃-SiO₂quaternary system.The CaO-MgO-Al₂O₃-SiO₂?CMAS?system glass ceramics is prepared by the traditional melting method and the nucleation crystallization two-step heat treatment system.The best heat treatment system of glass ceramics was studied by DTA,the growth process of glass nucleation,the number of crystal nuclei and the distribution of Cr element in nucleated glass were studied by density measurement and FESEM,and the types of chromite spinel nucleation in glass nucleation were studied by fesem-eds and detoxification experiment of nucleated glass Mechanism of chromium fixation during nucleation.In the process of crystallization,XRD was used to study the types of devitrification of glass ceramics;density measurement and FESEM were used to study the effect of composition on the growth process,devitrification quantity and distribution of Cr element in the crystallized glass;universal testing machine and Vickers hardness tester were used to test the conventional mechanical properties of the product;toxic leaching test was used to test the chemical stability of the glass;and devitrification was used to test the chemical stability of the glass The crystallization kinetics of glass was studied.The results show that Cr₂O₃ nucleating agent forms chromite spinel with MgO,Fe₂O₃ and other oxides in the glass during the nucleation process,and the number of crystal nuclei increases with the increase of composition.The surface scanning results show that the distribution of chromium element in the glass is uniform.During the crystallization process,diopside grows on the basis of spinel,and the number of crystals increases with the increase of composition.XRD results show that the glass crystal phase is diopside and aluminum diopside.When the composition of S3 is used,the effect of nucleation and chemical stability of glass is the best,its compressive strength is 691.4MPa,Vickers hardness is 996.7HV,and chromium leaching is only0.0159mg/L.At the same time,the kinetic study shows that the crystallization process of this formula is the whole crystallization,its crystal growth index is n=4.11,and the crystallization activation energy is 208KJ/mol.