Effect Of Typical Components On Sulfur Migration In Refining Waste Slag Of Electric Field Enhanced

As a by-product of secondary refining sulfur-containing refining waste slag has an annual output of tens of millions of tons.Effective recycling of these by-products is essential to improve the sustainable development of the steel industry.However,the recycling of refining waste slag for road construction,cement production,pelletizing,steel making slagging agent,preparation of protective slag and other recycling methods are limited because of the high sulfur content of refining waste slag to the environment and smelting.It is difficult to remove sulfur by general oxidation and hydrothermal methods because of the complex form of sulfur in refining waste residue.In view of this,sulfur migration between slag and metal is an electrochemical reaction process,which provides a theoretical basis for the control of sulfur migration by applied electric field.Therefore,the structure and properties of refined slag（Ca O/Al₂O₃（C/A）=1.2-2.0,Ca O/Si O₂（C/A）=2.3-3.2,w（Mg O）=4-8 wt.%and w（F^-）=3-7 wt.%）are tested by spectroscopic experiment,X-ray diffraction,rotary viscometer,four-probe method and hemisphere point method.Then,the effects of different components（C/A=1.2,1.6,2.0and w（Mg O）=4 wt.%,8 wt.%,12 wt.%）and electric field conditions（U=0V,2V,4V,6V）on the transfer efficiency of sulfur from slag to molten iron are studied,and the effect of electrochemical conditions on the properties of slag itself is obtained.The structure and performance analysis of the refining slag shows that with theincrease of C/A ratio in the range of 1.2-2.0,the slag network structure depolymerization and high melting point ore phase disappeare,resulting in a monotonically decreasing viscosity and a monotonically increasing electrical conductivity.With the increase of basicity in the range of 2.3-3.2,the slag network structure depolymerization-polymerization-depolymerization.The viscosity shows a decreasing-increasing-decreasing trend,while the electrical conductivity shows an opposite trend.With the increase of w（Mg O）in the range of 4-12 wt.%,the viscosity decreases first and then increases,and the conductivity increases first and then decreases under the influence of slag network depolymerization and high melting point ore precipitation.With the increase of w（F^-）in the range of 3-7 wt.%,due to the influence of slag network structure,the viscosity decreases first and then increases,and the trend of electrical conductivity is opposite.The experimental results of applying electric field on refining slag to enhance sulfur migration show that when the electric field is not applied,the sulfur element migrates to molten iron within 1 h,the higher the C/A ratio is,the more the sulfur element migrates to molten iron,and the sulfur element gradually return to the slag with time.Under the two experimental conditions of electric field is applied within 0.5 h for slag-metal reaction and slag-metal reaction after 0.5 h,the sulfur content in slag decreases gradually with the increase of slag C/A ratio when the voltage is 0-4 V,and the sulfur content in slag increases gradually when the voltage is 6 V,and the former method has a higher sulfur migration efficiency in slag.When the voltage is 0-4 V,the sulfur content in slag decreases first and then increases with the increase of Mg O content;when the voltage is 6 V,the sulfur content in slag increases first and then decreases.The electric field experiment results of slag system with C/A ratio and Mg O content are changed that in the range of voltage U=0-4V,the electric field and the simplification of slag network structure had obvious promoting effect on sulfur removal from slag.The effect of electric field applied to refining slag on slag structure and properties show that with the increase of voltage,the slag network structure depolymerizes.Combining the electric field experiment results of changing the C/A ratio and Mg O content slag system,it is found that increasing the voltage can depolymerize the slag structure,reduce the melting point,the electrical conductivity of the slag increase first and then decrease,and the structure,melting point and electrical conductivity of the slag change significantly with the decrease of the viscosity and the increase of the voltage.