Mineralogical characteristics,metallurgical properties and phase structure evolution of Ca-rich hematite sintering

In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.

Analysis of Thermal-Fluid-Structure Coupling and Resonance Forecast for Link Butterfly Valve Under Small Opening

When the link butterfly valve operates at a small opening degree in high temperature working conditions,it is prone to the problem that the valve is stuck,the strength is insufficient and the butterfly plate is violently vibrating.This paper shows simulation experiments of both thermal-fluid-structure coupling and resonance forecast about DN600 link butterfly valve in the working conditions of 250℃and 0.5 MPa by ANSYS software.The medium is mixed with compressed air and flue gas.Flow field characteristics of the valve and stress deformation,modal and flow-induced vibration of butterfly plate are analyzed when the valve opening is less than 30%.The results indicate that,when the valve opening is less than 30%,fluid flow is relatively smooth in front of butterfly plate,a large number of vortexes are found behind the butterfly plate,and fluid flow is greatly chaotic in this position.The equivalent maximum stress and deformation of butterfly plate are relatively large when the valve locates in openings between 10%and 30%;the intensity of the butterfly plate is enough;the axial deformation does not impact opening and closing of the valve.The butterfly plate is likely resonant when the valve opening is less than 10%.The research of this paper provides a crucial reference for flow field characteristics of link butterfly valve,an analysis of intensity and rigidity of butterfly plate,and a resonance forecast of butterfly plate when the valve works in small opening.