Slag attack evaluation of in situ spinel-containing refractory castables via experimental tests and thermodynamic simulations

Although the in situ spinel formation in alumina-magnesia refractory castables induces an expansive behavior, many investigations highlight its positive role in the corrosion resistance of such materials. Thus, this work addresses the slag attack evaluation of four designed in situ spinel-containing castables (containing hydratable alumina or calcium aluminate cement as a binder source and 0 or 1 wt% of silica fume) when in contact with a Fe_xO rich industrial slag. Corrosion cup-tests, microstructural characterization and a two-step thermodynamic simulation model were used in order to investigate the reactions taking place during the slag-refractory interactions. According to the attained results, hydratable alumina seems to be a suitable binder to improve the corrosion resistance of such castables, as it induces densification and the formation of an alumina-rich spinel phase at the slag-matrix interface. Moreover, the thermodynamic calculations matched to the experimental observations, attesting the efficiency of the proposed simulation model for the evaluation of the in situ spinel-containing castable corrosion behavior.     

计算机分析Al2O3-SiO2系耐火材料的抗FeO侵蚀性能

采用C Builder编制程序绘制了 16 0 0℃下FeO -Al2 O3-SiO2 三元系等温截面图 ,在此基础上 ,判断不同组分的Al2 O3-SiO2 系材料抗FeO侵蚀能力的优劣。该程序具有界面好、使用便捷、准确的特点。     

含钒渣对铝碳材料的侵蚀

为了探讨含矾渣对铝碳材料的侵蚀机制,用动态感应抗渣法研究了w(V2O5)=10%、碱度2.8,w(V2O5)=6%、碱度2.8,w(V2O5)=6%、碱度1.44的3种含钒渣对铝碳材料的侵蚀。结果表明:随着V2O5含量(w)由6%增加到10%,铝碳材料的熔损指数增加;随着碱度的增加,铝碳材料的熔损指数也增加;添加电熔镁砂有助于提高铝碳材料的抗侵蚀性能。显微分析表明:V、Ti元素渗透能力强,渗透深,而尖晶石可固溶少量V2O5、MnO及FeO。     

Thermodynamic evaluation of spinel containing refractory castables corrosion by secondary metallurgy slag

This work addresses the thermodynamic evaluation of different spinel-containing refractory castable compositions in contact with a basic steel ladle slag (CaO/SiO₂ ∼ 9). The main differences among the castable compositions were the amount of silica fume (0 or 1 wt%), the binder source (calcium aluminate cement or hydratable alumina) and the spinel incorporation route (in situ or pre-formed). The interaction of the liquid slag with the refractory was carried out with the help of thermodynamic software (FactSage) and the applied methodology considered the changes in the slag composition due to the interaction with the castable. The theoretical results were compared with the experimental data attained by corrosion cup-tests, pointing out that the thermodynamic calculations were suitable for predicting various aspects observed in the corroded samples by SEM. Therefore, the equilibrium simulations led to parameters that indicated the corrosion resistance trends, complementing the experimental evaluation and reducing further experimental testing.     

Al2O3-C-TiC质耐火材料的侵蚀行为

模拟铁浴式熔融还原工艺,采用固定床预还原法对铁矿石进行预还原、在矿热电炉上进行终还原熔炼试验,研究和测试了Al2O3-C-TiC质耐火材料的侵蚀特征和侵蚀机理,分析了熔体组成与性质对耐火材料侵蚀过程的影响及熔体侵蚀过程中耐火材料的物相组成和结构变化规律.     

Effects of La2O3 on the viscosity of copper smelting slag and corrosion resistance of magnesia refractory bricks

The rotating method is carried out to investigate the effects of La₂O₃ content (0–4 wt%) on the viscosity of copper smelting slag at high temperatures, the apparent activation energy is evaluated according to the Arrhenius equation and the structural characterization of this quenched slag is characterized by Raman spectroscopy. Meanwhile, the corrosion resistance of copper smelting slag with different content of La₂O₃ on magnesia refractory bricks is researched by employing a static crucible method. The experimental results show that the viscosity of copper smelting slag decreased with the La₂O₃ ratio increases from 0 to 3 wt% in a certain temperature range, which is because La₂O₃ simplifies the structural units of [SiO₄] tetrahedral groups. However, the melt viscosity increases after add 4 wt% La₂O₃, the reason is that more La₂O₃ addition improves the structural compactness of [SiO₄] tetrahedral groups in the molten slag due to the strong accumulation effect of La³⁺. Observation of the corroded samples found that the corroded magnesia refractory brick has a lower penetration index when the copper smelting slag with the content of 4 wt% La₂O₃. Therefore, the copper smelting slag containing 4 wt% La₂O₃ has a higher viscosity, and thus impeded the penetration behavior of copper smelting slag on magnesia refractory bricks.     

电熔锆刚玉对Al_2O_3-SiO_2系浇注料抗铅渣侵蚀性的影响

以特级高铝矾土(粒度为8～5、5～3、3～1和≤1 mm)为骨料,电熔棕刚玉粉(≤0.044 mm)、α-Al2O3微粉(≤5 μm)和SiO2微粉(≤1μm)为细粉,铝酸钙水泥(Secar 71)为结合剂制备了卡尔多炉直升烟道用Al2O3-SiO2系浇注料.用电熔锆刚玉粉(≤0.044 mm)部分替代棕刚玉粉,采用静态坩埚法(1 300℃5 h,空气气氛)研究了添加物电熔锆刚玉的加入量(质量分数分别为4%、8%、12%、16%)对Al2O3-SiO2系浇注料抗铅渣性的影响,对抗渣前后试样的显微结构进行了分析.结果表明:加入锆刚玉后,浇注料的抗铅渣性能得到明显改善,其适宜加入量为8%;显微结构分析表明,铅渣对Al2O3-SiO2系浇注料的侵蚀主要表现为铅渣中的PbO与Al2O3-SiO2系浇注料中的SiO2、CaO反应,生成硅酸铅或铅酸钙等低熔物而导致浇注料的损毁;而浇注料的添加物锆刚玉中的ZrO2未与PbO反应,从而使浇注料表现出良好的抗铅渣侵蚀性.     

镁铝钛耐火材料的Al2O3含量与其性能的关系

分别以79.3%~85.3%(质量分数,下同)的电熔镁砂、10%的电熔尖晶石、电熔白刚玉(2.5%~8.5%)和钛白粉(2.2%和5.5%)为原料制备了2组镁铝钛试样,研究了镁铝钛材料中Al2O3含量(分别约为7%、10%和13%)对其烧结、抗热震性以及抗炉外精炼渣侵蚀性的影响,并借助SEM、EDS分析了侵蚀后试样的显微结构。结果表明:随着镁铝钛试样中Al2O3含量的增加,试样更易烧结,烧后显气孔率降低,体积密度升高,抗渣性能提高;Al2O3含量的增加,使试样中的尖晶石数量增多,而尖晶石和方镁石热膨胀系数的差异形成的微裂纹,使试样的耐压强度降低,抗热震性提高;显微结构分析显示,随着Al2O3含量的增加,试样中析出的晶间尖晶石增多,有助于提高试样中的固-固结合率,从而增强其抗侵蚀能力。     

Al2O3-SiC-C耐火材料抗CaO-SiO2-K2O渣侵蚀性能研究

研究了Al2O3-SiC-C耐火材料的抗CaO-SiO2-K2O渣侵蚀性能,以及添加Cr2O3对Al2O3-SiC-C材料抗渣侵蚀性能的影响.研究结果表明CaO-SiO2-K2O熔渣对Al2O3-SiC-C材料具有明显的侵蚀作用;在Al2O3-SiC-C材料中添加适量的Cr2O3可以有效地抑制CaO-SiO2-K2O熔渣向耐火材料内部的渗透,降低耐火材料的侵蚀速度.     

连铸保护渣对O’－Sialon－ZrO_2复合材料侵蚀的研究

研究了保护渣对Ｏ’－Ｓｉａｌｏｎ－ＺｒＯ２复合材料的侵蚀情况，并与ｔ－ＺｒＯ２材料对比。结果表明．保护渣对ｔ－ＺｒＯ２的侵蚀小于Ｏ’－Ｓｉａｌｏｎ－ＺｒＯ２材料；ＺｒＯ２引入量的增多，有利于Ｏ’－Ｓｉａｌｏｎ－ＺｒＯ２制品抗渣性能的提高。这可能是由于ＺｒＯ２在保护渣中的溶解度较小，渣中ＣＯ与Ｏ’－Ｓｉａｌｏｎ的反应及渣中多元成分与Ｏ’－Ｓｉａｌｏｎ共同作用的结果。     

Comparison study on effect of nano-sized Al2O3 addition on the corrosion resistance of microporous magnesia aggregates against tundish slag

The microporous magnesia aggregates show a promising application prospect as tundish lining, due to the excellent thermal insulation. In this study, the effect of nano-sized Al₂O₃ addition on the corrosion resistance of microporous magnesia aggregates against tundish slag is explored. The results show that the addition of nano-sized Al₂O₃ deteriorates the slag resistance of microporous magnesia aggregates, which is mainly because that the apparent porosity of aggregates increases with the addition of nano-sized Al₂O₃. Furthermore, MgO·Al₂O₃ spinel is formed in situ at the grain boundaries of Al₂O₃-bearing aggregates and the dissolution of MgO·Al₂O₃ spinel into molten slag damages the structure of aggregates. For the Al₂O₃-free microporous magnesia aggregates, as expected, the penetration of high basicity slag (CaO/SiO₂ = 9, mass ratio) into refractory is slighter than that of low basicity slag (CaO/SiO₂ = 4, mass ratio). But, for the Al₂O₃-bearing microporous magnesia aggregates, the corrosion of refractory by high basicity slag is severer. This is mainly because that MgO·Al₂O₃ spinel is more unstable in high basicity slag. Therefore, it is not suitable to add nano-sized Al₂O₃ for the preparation of microporous magnesia as tundish lining.     

Corrosion behavior of carbon,Al2O3, and MgO refractories during the preparation of a Ti–Si–Al alloy via the aluminothermic reduction of a Ti-bearing blast-furnace slag

The extraction of Ti from Ti-bearing blast-furnace slag (TBFS) via aluminothermic reduction to prepare Ti–Si–Al alloy has several promising applications. However, the refractories of the furnace lining can dissolve into the molten slag and change the composition of the slag, not only shortening the life of the refractories, but also influencing the preparation of Ti–Si–Al alloys for industrial applications. The main purpose of this study was to explore the corrosion behavior of refractories (carbon, alumina, and magnesia bricks) and determine the most suitable refractories for the aluminothermic reduction of TBFS. Herein, for the first time, the dissolution equilibrium of refractories during the aluminothermic reduction of TBFS and its effect on aluminothermic reduction were revealed. The results revealed that the alumina and magnesia bricks were more effective for obtaining bulk Ti–Si–Al alloy and avoiding high mass loss of the Ti–Si–Al alloy compared to the carbon bricks. Furthermore, the corrosion of alumina and magnesia bricks increased with an increase in the content of the added CaO; however, the corrosion of the alumina bricks was more severe compared to the magnesia bricks. In addition, the largest extraction ratio of Ti (maximum value: 99.85%) was achieved when magnesia bricks were employed. The results of this study indicate that magnesia bricks are the optimal refractory for the preparation of Ti–Si–Al alloy via the aluminothermic reduction of TBFS. This work provides important experimental information for the industrial application of the aluminothermic reduction of TBFS in the preparation of Ti–Si–Al alloys.     

添加铝铬渣的钢包水口座砖的研制和应用

为降低钢包水口座砖的生产成本,在0#浇注料配方(w):电熔白刚玉骨料70%、电熔白刚玉细粉10%、α-Al2O3微粉+镁铝尖晶石+氧化铬微粉15%、铝酸钙水泥5%的基础上,以等粒度铝铬渣骨料全部取代电熔白刚玉骨料(1#配方),再在1#配方的基础上以铝铬渣细粉全部取代电熔白刚玉细粉(2#配方),配制成3种浇注料,经搅拌、振动浇注成型、养护、干燥以及1 100和1 550℃热处理后,检测试样的体积密度、强度、抗热震性和抗侵蚀性等性能。结果表明:1)110℃烘干后,与0#试样相比,1#试样的体积密度变化不大,显气孔率略有升高,抗折强度略有降低,耐压强度显著提高;而2#试样的各项性能均有不同程度的下降。2)1 100和1 550℃热处理后,1#试样的各项性能指标均有比较明显的改善,高温抗折强度明显提高,抗渣侵蚀性优良,但抗热震性下降;而2#试样除高温抗折强度外其余各项性能下降明显。按综合性能最佳的1#配方制备的钢包水口上座砖在某钢厂60 t钢包上使用,1次寿命达80~90炉次,修补后寿命达110~120炉次,与钢包寿命同步。     

Al_2O_3－SiC－C质浇注料抗热震性和抗渣铁侵蚀性的研究

对新研制的Ａｌ２Ｏ３－ＳｉＣ－Ｃ质浇注料和现用出铁沟料的抗热震性和抗渣铁侵蚀性进行了研究、结果表明，该材料具有较高的抗渣铁侵蚀能力和较好的抗热震稳定性。调节Ｓｉ与Ｃ的比例可生成高强度、耐渣蚀的纤维状ＳｉＣ。     

硅溶胶结合Al2O3-SiC-C浇注料的抗侵蚀性能

以致密刚玉、碳化硅、炭素材料、氧化铝微粉、刚玉微粉等为原料,以硅溶胶为结合剂制备了Al2O3-SiC-C浇注料,与高炉出铁场应用的主沟铁线料、渣线料以及脱Si用摆动流嘴料对比进行了抗高炉水渣、脱Si渣和脱P渣侵蚀试验研究,侵蚀试验采用静态坩埚法(氧化气氛,1450℃3h)和动态旋转法(1500℃,转速为60r.min-1,试验旋转时间10min)两种方法进行。另外,对所研制的浇注料又进行了静态坩埚强化侵蚀试验:1500℃3h抗渣侵蚀试验和2次1450℃3h抗渣侵蚀试验。结果表明:所研制的硅溶胶结合Al2O3-SiC-C浇注料对3种渣的抗侵蚀性能均比目前高炉出铁场使用的主沟铁线料、渣线料以及脱Si用摆动流嘴料要好;在3种铁水预处理渣中,脱Si渣和脱P渣对材料的侵蚀较严重。     

纯铝酸钙水泥对镁铝钛系浇注料性能的影响

以镁铝钛电熔合成料颗粒和细粉(w(MgO)76.09%,w(Al2O3)15.67%,w(TiO2)5.05%)、镁砂细粉(w(MgO)>97.1%)、纯铝酸钙水泥(Secar71)、SiO2微粉、SiC细粉(≤0.074mm)及活性氧化铝微粉为原料制成镁铝钛系浇注料,研究了纯铝酸钙水泥含量(分别为2%、4%、6%)对镁铝钛系浇注料性能的影响,结果表明(1)水泥结合的镁铝钛浇注料具有较好的常温物理性能和抗水泥熟料侵蚀的性能,本试验条件下水泥加入量以<4%为宜;(2)高温下镁铝钛电熔合成料存在TiO2的脱溶现象,而脱溶可能对浇注料的理化性能产生影响;(3)在水泥结合镁铝钛系浇注料中加入SiC,对于抑制浇注料收缩是有益的。     

含TiO2高炉渣对Sialon结合SiC材料的侵蚀行为

实验考察了含TiO2 高炉渣对Sialon结合SiC耐火材料的侵蚀行为。结果发现 ,渣中TiO2含量仅为 1 .0 5%时 ,耐火材料中将形成Ti(C、N) ,并积聚于工作带 ,阻止熔渣的进一步侵入 ,从而延长了SiC材料的使用寿命     

高铝粉煤灰加入量对Al2O3-SiC-C浇注料抗高炉渣性能的影响

以棕刚玉(w(Al_2O_3)≥95.00%,粒度8~1mm,≤1mm),SiC(w(SiC)≥90.00%,粒度≤0.088mm),铝酸盐水泥,α-Al_2O_3微粉,SiO_2微粉,高温沥青等为原料,研究了高铝粉煤灰加入量(质量分数,下同)分别为0、3%、6%、9%和12%时对Al_2O_3-SiC-C质浇注料物理性能和抗渣性能的影响。结果表明随着高铝粉煤灰加入量的增加并达到9%时,Al_2O_3-SiC-C质浇注料的线变化率略有增大,抗渣性能与未添加粉煤灰的浇注料的相当;当高铝粉煤灰添加量增加并达到12%时,试样的抗高炉渣侵蚀的能力开始较明显下降。     

The phase conversions and properties of refractories based on the MgO-Al2O3-Cr2O3system

Conclusions An investigation of the phase conversions in the MgO-Al₂O₃-Cr₂O₃ system at a below-unity ratio MgO/R₂O₃ and varied content of sesquioxides showed that the magnesiochromite initially being formed in all mixtures interacts with the Al₂O₃ at temperatures above 1000°C with the result that two kinds of solid solutions are formed, viz., a spinel one Mg(Cr_xAl)_1–x)₂O₄ and (Al_xCr_1–x)₂O₃. The predominance of a given component in the original composition remains preserved in both phases.The presence was established of a solid solution of Al₂O₃ in the spinel phase which contained a signficant amount of MgAl₂O₄. No solid solutions of R₂O₃ are formed in the spinel when the chromite component predominates in both phases.The changes in the properties of the specimens correspond to the phase conversions. After high-temperature firing materials of the type Mg(Al, Cr)₂O₄-(Al, Cr)₂O₃ possess adequate property indices.The analysis is concerned with that part of the system for which MgO/(Al₂O₃ + Cr₂O₃) is less than unity.Translated from Ogneupory, No. 8, pp. 48–53, August, 1976.     

Optimization of corrosion resistance and mechanical properties of Al2O3-Cr2O3 refractories for waste incinerator

The corrosion resistance and mechanical properties directly affects the operation and service life of Al₂O₃-Cr₂O₃ refractories used in waste incinerators. In this study, ZrO₂ particles were introduced via vacuum impregnation to adjust microstructure and properties of Al₂O₃-Cr₂O₃ refractories. The results showed that the impregnated ZrO₂ particles and increasing impregnation times resulted in the decreased median pore size and increased compactness, and mechanical strengths of refractories were elevated from the inhibited cracks propagation by ZrO₂ particles. The decreased amounts of large pores and increased amounts of small pores from the filled ZrO₂ particles inhibited penetration of low melting point phases, and the formed CaZrO₃ phase from the reactions between corrosion reagent and ZrO₂ particles increased the viscosity of penetrated corrosion reagent, resulting in the decreased penetration index from 8.57% to 2.58%. Meanwhile, the filled ZrO₂ particles around alumina particles prevented reactions between molten corrosion reagent and alumina, leading to the decreased corrosion index from 3.78% to .74%. The decreased pore size and formation of CaZrO₃ phase were primary factors that enhanced the penetration resistance. And formation of wrapped layers from ZrO₂ particles around alumina particles presented prominent effects on the strengthened corrosion resistance of Al₂O₃-Cr₂O₃ refractories.