Study On Magnesia Structure And Impurity Regulation Based On Flotation Magnesite

With the continuous exploitation and utilization of mineral resources,high-grade magnesite resources are becoming more and more scarce,while low-grade magnesite cannot be directly used as a raw material for the production of high-quality refractory materials.In order to better develop and utilize low-grade magnesite,domestic and foreign scholars have carried out in-depth research on the purification and beneficiation of low-grade magnesite.As a widely used beneficiation method,flotation method can effectively reduce the content of impurities such as Caand Si.However,when magnesite is prepared from magnesite flotation powder,it is found that its sinterability is poor and its microstructure is not compact.It is found that there are residual flotation reagents in magnesite flotation powder,and the calcium-silicon ratio of magnesite flotation powder has changed greatly.Therefore,this thesis focuses on the above three aspects to study the crystal structure and impurity regulation of magnesia prepared by magnesite flotation powder.The microstructure and impurity distribution of magnesite prepared by magnesite and magnesite flotation powder were studied.The effect of flotation reagent residue on the microstructure and impurity distribution of magnesia was investigated.The impurity distribution of Caand Siwas controlled by changing the Ca/Siby using analytically pure reagents to simulate the oxide content in magnesia.The results show that:1.When magnesite flotation powder was used as raw material to prepare light-burned magnesium oxide,the activity of light-burned magnesium oxide was the highest when the raw material particle size was 325 mesh and the calcination condition was 750℃for 1h.2.There is no obvious difference in crystal structure between magnesite and magnesite flotation powder;the periclase grains in the magnesia made from magnesite are evenly distributed and the structure is dense.Caand Siimpurities appear at the same time and are evenly distributed.Caand Siimpurities are distributed between the periclase grains in the form of CMS.The particle size of magnesia prepared by flotation powder is small,and the combination between crystals is not close.Caand Siimpurities are concentrated in pores or crystal defects.Caimpurities exist in the forms of CaO,C₂S and C₃S,respectively.Sigenerally coexists with Caimpurities to form C₂S and C₃S.3.The residual amount of flotation reagents has no effect on the crystal structure of magnesia,in which the distribution of Caimpurities is irregular,Siimpurities generally exist at the same time as Caimpurities.Due to the surface tension of the liquid,some Caand Siimpurities are concentrated in the pores,microcracks and crystal defects with the flotation reagents.4.The content of CaO and SiO₂has little effect on the crystal structure of magnesia and the distribution of Caand Siimpurities.The ratio of calcium to silicon has a great influence on the crystal structure of magnesia and the distribution of Caand Siimpurities.The smaller the ratio of calcium to silicon,the better the development of periclase crystal,the less the intercrystal gap,the more uniform the distribution of Caand Siimpurities,and the best ratio of calcium to silicon is 0.5.