Reaction behavior of MgO refractory with high-Mn and high-Al steel

To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were investigated.It was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al_(2)O_(3) spinel and(Mn,Mg)O solid solution.The formation mechanism of the spinel and solid solution is as follows.The Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al_(2)O_(3) spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al_(2)O_(3) spinel.Finally,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid solution.In addition,only(Mn,Mg)O·Al_(2)O_(3) spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.

Influence of crucible material on inclusions in 95Cr saw-wire steel deoxidized by Si–Mn

To investigate the interaction mechanism between 95 Cr saw-wire steel and different refractories,we conducted laboratory experiments at 1873 K.Five crucible materials(SiO2,Al2 O3,MgO·Al2 O3,MgO,and MgO-CaO)were used.The results indicate that SiO2,Al2 O3,and MgO·Al2 O3 are not suitable for smelting low-oxygen,low-[Al]s 95 Cr saw-wire steel,mainly because they react with the elements in the molten steel and pollute the steel samples.By contrast,MgO-CaO is an ideal choice to produce 95 Cr saw-wire steel.It offers three advantages:(ⅰ)It does not decompose by itself at the steelmaking temperature of 1873 K because it exhibits good thermal stability;(ⅱ)[C],[Si],and[Mn]in molten steel cannot react with it to increase the[O]content;and(ⅲ)it not only desulfurizes and dephosphorizes but also removes Al2 O3 inclusions from the steel simultaneously.As a result,the contents of the main elements([C],[Si],[Mn],[Cr],N,T.O(total oxygen))in the steel are not affected and the content of impurity elements([Al]s,P,and S)can be perfectly controlled within the target range.Furthermore,the number and size of inclusions in the steel samples decrease sharply when the MgO-CaO crucible is used.

Effect of High Coal Injection on Low Silicon Ironmaking Process

The effects of Fe 2O 3 addition in MgO CaO refractory on desulfurization of liquid iron were studied by SEM, EDA and chemical analysis. Fe 2O 3 of 1 % and 4 % were added to MgO CaO refractory as the lining of graphite crucible in which 150 g iron powder with sulfur of 0 15 % was charged. It is found that when the sample is heated at 1 600 ℃ for 40 min, 60 min and 90 min, the addition with Fe 2O 3 of 1 % improves desulfurization greatly. However, the desulfurization ratio of the refractory with Fe 2O 3 addition of 4 % is less than that with Fe 2O 3 addition of 1 %. For the soaking time of 90 min, the desulfurization ratio is less than those of 40 min and 60 min. These phenomena were explained by the contrary roles of O 2- and Fe 2+ formed by reaction between liquid iron and Fe 2O 3 on desulfurization.

Wetting and corrosion behavior between magnesia-carbon refractory and converter slags with different MgO contents

The influence of MgO content in slag on wetting and corrosion behavior between slag and MgO–C refractory was investigated.It can be known from the high-temperature wetting experiment that as the MgO content in the slag increases,the final contact angle between the slag and the MgO–C refractory gradually increases and the penetration depth of the slag into the refractory gradually decreases from 60.54μm(when the MgO content is 8%)to 28.11μm(when the MgO content is 12%).The CaO and SiO_(2)in the slag penetrate into the MgO–C refractory along the pores or surface cracks formed by carbon oxidation and react with MgO to generate a large amount of low-melting compound CaO–MgO–SiO_(2),which accelerates the corrosion of the refractory.As the MgO content in slag increases,the viscosity of the slag increases and the fluidity becomes worse,so that the mass transfer and diffusion of molecules or ions in the slag are weakened.In addition,the increase in MgO reduces the activity of FeO in the slag,which inhibits the interfacial chemical reaction,thereby weakening the wetting effect caused by the reaction.

Enhanced oxidation resistance of low-carbon MgO-C refractories with ternary carbides:a review

The demand for low-carbon MgO–C refractories is ever growing to meet the development of advanced steelmaking technologies and efficient energy conservation.Meanwhile,to improve the oxidation resistance and inhibit the weakness of low-carbon MgO–C refractories,antioxidants are necessary.The application of ternary carbides that focused on improving the oxidation performance of MgO–C refractories has been explored,and the ternary carbides including Al_(4)O_(4)C,Al8B_(4)C_(7),Al_(4)SiC_(4),Ti_(2)AlC,Ti_(3)AlC_(2),and Ti_(3)SiC_(2)have been proved effective.The crystal structure,physical properties,oxidation behavior,and synthesis of these ternary carbides were summarized,and their oxidation mechanism in assisting antioxidation of MgO–C refractories was discussed.In addition,the potential aspects related to the usage and development of ternary carbides in low-carbon MgO–C refractories were proposed.

Influence of pre-synthesized Al_(2)O_(3)-SiC composite powder from clay on properties of low-carbon MgO-C refractories

To improve the properties of low-carbonization of MgO–C refractories,the introduction of composite additives is an effective strategy.Al_(2)O_(3)–SiC composite powder was prepared from clay using electromagnetic induction heating and carbon embedded methods.Further,the Al_(2)O_(3)–SiC composite powder synthesized by electromagnetic induction heating at 600 A was added into low-carbon MgO–C refractories(4 wt.%)to improve their properties.The results showed that when the addition amount of Al_(2)O_(3)–SiC composite powder is within the range of 2.5–5.0 wt.%,the properties of low-carbon MgO–C samples were significantly improved,e.g.,the apparent porosity of 7.58%–8.04%,the bulk density of 2.98–2.99 g cm-3,the cold compressive strength of 55.72–57.93 MPa,the residual strength after three air quenching at 1100°C of 74.86%–78.04%,and the decarburized layer depth after oxidized at 1400°C for 2 h of 14.03–14.87 mm.Consequently,the idea for the rapid synthesis of Al_(2)O_(3)–SiC composite powder provides an alternative low-carbon MgO–C refractories performance optimization strategy.