Study On Magnesium Slag Desulfurizer Modified By Additives In Quenching Hydration

The desulfurization performance of the magnesium slag has been improved by hydration activation,steam activation and hydration with mixing fly ash.However,it is still unable to realize the industrialized production.More effective method is urgent to be studied to improve the desulfurization performance.Based on the previous research results such as methods of quenching slag and modification study of additives to calcium based sorbents,NaCl,CaCl2,Na2SO4,CaSO4,Na2CO3,K2CO3,acetic acid,adipic acid and calcium lignosulfonate were used to modify quenching magnesium slag in the thesis.The effect of hydration temperature and hydration time on the desulfurization performance of modified desulfurizer was studied by setting different hydration temperature and selecting different hydration time.Under the conditions of laboratory,the desulfurization performance of modified desulfurizers was tested by TGA,elemental composition of magnesium slag was determined by ICP-AES,and SEM,EDS,XRD and BET were used to study the apparent morphology,composition and microstructure parameters of the modified desulfurizers.The principles of modification of different additives were obtained.The main results of this thesis are as follows:（1）Quenching hydration can significantly enhance the desulfurization performance of magnesium slag.（2）Under the experimental conditions of this thesis,the optimal working conditions of each additive are: 1% NaCl,1% CaCl2,2% Na2SO4,2% CaSO4,4% Na2CO3,4% K2CO3,1% acetic acid,1% adipic acid and 2% CLS.The calcium conversion rate of 16# which is modified by 2% Na2SO4 reaches to 40.16%.The optimal hydration temperature is 80℃.（3）It was found that there is a critical hydration time of 4# which is modified by 1% NaCl after hydrated 6h.When the organic acid additive is added in hydration,the conversion rate of the modified desulfurizer decreases with the increase of hydration time.And 8h is the optimal hydration time of other additive modified desulfurizers.（4）The adsorption isotherms of quenching hydrated magnesium slag desulfurizer modified by different additives are all similar to the type II isotherm.The results indicate that the pore type of Cl-modified desulfurizer and CaSO4 modified desulfurizer mainly belongs to flat plate pore because their hysteresis loop is class B.While the pore type of Na2SO4 modified desulfurizer and CLS modified desulfurizer is mainly the slit pore due to their class H3 hysteresis loop,indicating that them.（5）Cl-and SO₄^2-are mainly used to improve the microstructure of quenching hydrated magnesium slag such as specific surface area and pore volume,consequently promoting the desulfurization efficiency of modified desulfurizer.The microscopic parameters of Na2SO4 modified desulfurizer is best,whose specific surface area and pore volume can reach 27.052 m2·g-1and 0.00785 cm3·g-1,respectively.（6）CO₃^2-can react with Ca（OH）2 which is the product of quenching hydrated magnesium slag and generate CaCO3.CaCO3 crystallizes on the surface of the magnesium slag,and thus the desulfurization performance of CO₃^2-modified desulfurizer is improved.（7）The addition of organic acid can increase the concentration of H+ in hydrated slurry,which can promote the dissolution of Ca2SiO4 in the magnesium slag in the liquid phase.（8）In the process of hydration,the addition of CLS has effect on the dispersion of magnesium slag to some extent,which makes magnesium slag become fine particles.Even though it can improve the desulfurization capacity of CLS modified desulfurizer,the effect of improving desulfurization capacity is small.