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.     

铁浴式熔融还原渣对镁铬材料侵蚀的研究

以市售w(Cr2O3)=26.02%的电熔再结合镁铬砖和自制预合成的不同FeO含量的铁浴式熔融还原渣为研究对象,采用旋转圆柱法,研究了铁浴式熔融还原渣中FeO含量(其质量分数分别为0、5%、10%和15%)和试验温度(1 450、1 500、1 550和1 600℃)对镁铬砖试样侵蚀量、显微结构的影响。结果表明:(1)不含FeO的渣对镁铬试样的侵蚀量大于FeO含量(w)为5%的渣,渣中FeO含量(w)为5%~15%时,随着FeO含量的增加,镁铬试样的侵蚀量增大,侵蚀加剧;(2)温度是影响镁铬材料抗渣性能的重要因素之一,温度提高,熔融还原渣对耐火材料的侵蚀加剧。     

铝铬砖和镁铬砖抗艾萨炉炉渣蚀损的模拟研究

采用回转抗渣法模拟研究了试验温度、保温时间和熔渣加入量等因素对铝铬砖和镁铬砖抗艾萨炉炉渣侵蚀能力的影响。用SEM、EDAX及XRD等方法,对抗渣试样的显微结构和矿物组成进行了分析研究。结果表明:随着侵蚀温度的升高、保温时间的延长及炉渣加入量的增加,铝铬砖和镁铬砖的侵蚀面积增大;熔渣渗入铝铬砖后,形成铁铝尖晶石和铁铬尖晶石保护层,阻止了熔渣的侵蚀;三种耐火材料抗艾萨炉炉渣侵蚀能力由强到弱为:铝铬砖>电熔再结合镁铬砖>直接结合镁铬砖。     

Influence of chrome-bearing sols vacuum impregnation on the properties of magnesia-chrome refractory

Two kinds of nanosized chrome-bearing sols, i.e. Cr₂O₃ precursor sol and MgCr₂O₄ spinel precursor sol, were obtained by homogeneous precipitation. Properties of the sol vacuum impregnated magnesia-chrome refractory, such as bulk density, cold crushing strength, pore distribution, and chemical composition, etc., are superior to those of the un-impregnated sample. SEM micrographs show a different microstructure of the impregnated sample as compared to the un-impregnated one. The influence of vacuum impregnation on copper slag corrosion resistance of magnesia-chrome refractories has also been evaluated. The results show that both sols could improve the magnesia-chrome bricks corrosion resistance in impregnation.     

炼铜诺兰达炉用镁铬砖损毁机理的探讨

简要介绍了诺兰达炉用耐火材料的现状,并以风口区使用后的镁铬残砖为试样,采用化学分析、SEM和EDAX等手段对其侵蚀机理进行了分析研究。结果表明:铜渣对镁铬耐火材料的侵蚀,在工作面以熔蚀为主;在砖体内部主要以锍渗透为主。锍渗透的主要途径为开口气孔、晶界及微裂纹。     

水煤浆气化炉用Cr2O3-ZrO2-Al2O3砖的蚀变过程

利用扫描电镜及能谱仪对水煤浆气化炉用进口铬锆铝砖的蚀变过程进行了显微观察与分析.结果表明此砖在水煤浆气化炉环境条件下的侵蚀主要由熔渣中的SiO2、CaO和P2O5引起;Cr2O3对这种渣蚀表现出很强的化学惰性,溶蚀很小,其使用过程中的主要变化是高温蒸发和在砖内蚀变液相作用下的溶蚀、溶析;而氧化锆蚀变生成的系列产物不仅在蚀变初期有利于保持砖结构致密,并且对蚀变后期基质连续网络结构的形成和保持也起了重要的作用.     

LF炉精炼渣对烧成镁钙砖的侵蚀机制研究

采用静态坩埚法研究了LF炉精炼渣对w(CaO)≈34%的烧成镁钙砖的侵蚀作用,并借助扫描电镜、能谱分析和X射线衍射分析了其对镁钙砖的侵蚀机制。研究结果表明:镁钙砖对LF炉精炼渣具有很强的抗侵蚀性能,但几乎不耐渗透;反应层中(Mg.Fe)O富氏体的氧化产生体积膨胀,从而造成镁钙砖开裂;渣中2CaO.Fe2O3(C2F)向砖内的渗透导致其内部液相增加,蚀损加速;2CaO.SiO2(C2S)能在反应界面形成保护层,能在一定程度上阻碍C2F向砖内的渗透。     

镁锆砖和镁铬砖的抗RH炉渣侵蚀性对比

为取代RH炉用镁铬材料,以电熔镁砂为主原料,分别加入单斜锆、脱硅锆、单斜锆与脱硅锆的混合粉、锆英石制备了ZrO2质量分数分别为15%和20%的镁锆砖,并利用静态坩埚法对比研究了镁锆砖和镁铬砖的抗RH炉渣侵蚀性。结果表明:对于Al2O3含量高且碱度(CaO/SiO2比)大的RH炉渣,镁锆砖抗侵蚀性能优于镁铬砖的;镁锆砖的侵蚀机理是砖中的ZrO2与渣中的CaO迅速反应,形成高熔点物相CaZrO3,能堵塞砖中的孔隙而形成致密保护层,从而阻止钢渣对镁锆砖的进一步侵蚀;而镁铬砖的侵蚀机理是渣中的Al2O3、Fe2O3等R3 和镁铬尖晶石中Cr3 交换,渣与砖反应生成的镁铝尖晶石和镁铁尖晶石使得材料变性,同时由于体积效应使镁铬材料鼓胀开裂,从而导致镁铬砖的严重侵蚀。     

含钛熔渣对镁炭质耐火材料的侵蚀

采用静态浸渍法和动态浸渍法研究了TiO2 含量在 2 .4%～ 30 %之间的含钛熔渣对镁炭质耐火材料的侵蚀 ,对侵蚀后试样进行了SEM、XRD和能谱分析 ,提出了含钛熔渣对镁炭质耐火材料的侵蚀机理 :熔渣与耐火材料接触并发生作用 ,熔渣中的TiO2 、FeO等氧化物使耐火材料氧化脱碳并且形成低熔物 ;脱碳及低熔物的熔出使耐火材料孔隙和通道增多 ,这反过来又使熔渣渗入耐火材料内部的速度加快 ,加速了对耐火材料的侵蚀     

钙长石结合莫来石轻质耐火砖的研究

研究了以蓝晶石作主要原料,以白水泥作结合剂生产钙长石结合莫来石轻质耐火砖的可行性。实验表明：蓝晶石从１２００℃开始莫来石化,到１３００℃基本完成,并与白水泥发生反应生成钙长石。钙长石结合莫来石轻质耐火砖体积密度为０．５ｇ·ｃｍ－３时的耐压强度超过３．５ＭＰａ,最高使用温度超过１４００℃,而３５０℃时的热导率只有０．１５Ｗ·（ｍ·Ｋ）－１。     

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.     

Corrosion behavior of silicon nitride bonded silicon carbide refractory material by molten copper and copper slag

Silicon Carbide refractories may be used in contact with copper and copper slags. The object for the investigation of corrosion by the melt of copper and the copper slag was SiC siphon block of the slag collector in the runner of the cathode shaft furnace. It is exposed to the permanent flow of copper with small amount of slag. Slag on the surface of the melt is stopped by siphon block and it suffers the most extensive corrosion wear, but the same time it is a good object for investigation, because different parts of this plate are exposed to intensive corrosion by different corrosive agents.General observations show, that the corrosion of Si₃N₄-SiC by slag is sufficiently more extensive and the wear is about 3 mm per month, while the wear by the flowing copper is below 1 mm per month.The observation of the cross section of the exposed Si₃N₄-SiC plate on macro level shows 4–5 zones of different color. Microstructural observations show almost no changes of the material in direct contact with molten copper without exposure of air, that suggests slow dissolution of Silicon Carbide and Silicon Nitride in the flowing melt of copper (physical dissolution in case of permanent removal of reactants). The most severe wear of Si₃N₄-SiC refractory is by slag, because the chemical erosion takes place.     

Enhanced corrosion resistance of magnesia-chrome refractories impregnated with zirconia sol

In order to enhance the corrosion resistance to molten vanadates and silicates of middle and upper checker bricks in glass furnace regenerator with petroleum coke as fuel, the present research improved the microstructure, compactness and corrosion resistance of magnesia-chrome refractories by vacuum impregnation with zirconia sol. The results show that the vacuum impregnation of zirconia sol and the increased impregnation times led to the significant increase in the bulk density and decrease in the apparent porosity of refractories, and the impregnated zirconia particles enhanced the corrosion and penetration resistance. The penetrated zirconia particles in the pores decreased the porosity and pore size of refractories, resulting in the inhibited penetration of vanadate and silicate liquid phases during the corrosion process. In addition, the zirconia particles around periclase particles also prevented the reaction between molten corrosion reagent and periclase, thus enhancing the corrosion resistance of refractories. The present study provides an effective method for improving the corrosion resistance of magnesia-chrome checker bricks in regenerator of glass furnace with petroleum coke as fuel.     

水煤浆气化炉耐火砖损蚀量的灰色预测

针对水煤浆气化炉中耐火砖存在损蚀的特点,采用灰色预测理论建立了耐火砖损蚀量的不等时距GM(1,1)预测模型,并提出了模型的优化方法。通过预测值与实际值比较得出,GM(1,1)模型用于水煤浆气化炉中耐火砖损蚀量的预测是可行的;优化后的预测模型与实际值吻合较好。在模型优化过程中还发现,模型优化后平均相对误差由4.41%降为3.73%,最大相对误差也由14.36%降到9.09%,验证了优化方法的有效性。预测结果可为水煤浆气化炉耐火砖的研制及检修提供依据和指导。     

Degradation mechanism of high alumina refractory bricks by reaction with deposits in a rotary kiln for fluxed iron ore pellets production

The formed deposits wear out of refractory wall linings in the rotary kiln and may cause production disturbances. This study describes the chemical composition and mineralogical phase components at the deposit/refractory interface in the rotary kiln for fluxed iron ore pellets production. The main phases of refractory bricks are corundum and mullite, while the deposits mainly contain hematite and silicates. The main phases in the deposit/refractory brick contact zone are hematite, anorthite (CaAl₂Si₂O₈), mullite, corundum, and silicates. Moreover, the hematite phases in the deposit/brick interface averagely contain 6.98 wt% Al and 1.38 wt% Ti. The silicates in the contact zone contain higher aluminium content and lower iron content than the silicates in the deposits. Finally, the thermodynamic analysis indicates that the main phases in the deposits can react with the refractory to form Al₂Fe₂O₆, CaAl₂Si₂O₈, feldspar, and liquid phases lead to the degradation of bricks in the kiln during the iron ore pellets production.     

Corrosion of high chromia refractory materials by basic coal slag under simulated coal gasification atmosphere

In this paper, dynamic corrosion experiment of a high chromia refractory interaction with basic coal slag under slagging gasifier conditions was conducted by using rotary drum corrosion test with the FactSage thermodynamic analysis. The microstructures and chemical compositions of the corroded samples were analyzed by scanning electron microscopy (BEI and EDS), and the corrosion mechanism was investigated by combining thermodynamic simulation and SEM analysis. The results show that the simulation results were consistent with the results of corrosion test. Reaction layer and penetration layer are formed from the surface to the interior of the sample after corrosion. The (Mg, Fe) (Al, Cr)₂O₄ spinel solution was formed in the reaction layer, which make the matrix structure become dense and change the overall structure of the particles’ uniformity. Corrosion of Cr₂O₃ aggregate is relatively weak by slag. The Cr₂O₃ dissolves into the slag through the formed spinel solution layer on the surface of aggregates. While, Cr₂O₃ and Al₂O₃ dissolve into molten slag through the spinel solution layer formed in the matrix. ZrO₂ in the matrix directly dissolved into molten slag and penetrates inner the matrix with the penetration of the slag to form a ZrO₂-free region. The liquid sintering of the matrix has happened in the melt, causes the structure of the penetration layer become dense, which is different from that of the original sample.     

Functionalization of nano-MgCr2O4 additives by silanol groups: a new approach to the development of magnesia-chrome refractories

This work describes a novel approach to improve the dispersion of a nanoparticle MgCr₂O₄ additive in the matrix of magnesia-chrome refractories by functionalizing the nanoparticle surfaces with silanol groups. The effect of the silanol groups on the nanoparticles within the refractory matrix was shown by FTIR spectroscopy, zeta potential measurements, UV–visible spectroscopy, Dynamic Light Scattering (DLS) and TEM to result in a decrease of the average particle size of the MgCr₂O₄ additive by about 50% due to de-agglomeration of the nano particles by the silanol groups. Silanol functionalization of the nano-additives in the magnesia-chrome refractories fired at 1600 °C resulted in a 65 Kgf/cm² increase in their compressive strength, while the hot modulus of rupture and corrosion resistance values of these refractories fired at 1400 °C were similar to those containing unfunctionalized nano-additives fired at 1600 °C. XRD and SEM results suggest the improvement in corrosion resistance is related to the formation of spinel phases in the refractories containing silanol-modified nano-additives.     

锆英石对铝铬锆砖抗侵蚀性能及六价铬形成的影响

铝铬锆砖因具有优异的抗渣侵蚀性能,被作为炉衬材料广泛应用于工作环境恶劣的危废焚烧炉。然而,铝铬锆砖在制备和服役过程中可能形成有毒的水溶性Cr(VI),相关研究工作却未见报道。本研究分别以单斜氧化锆和锆英石为氧化锆源制备了两种铝铬锆砖,研究了铝铬锆砖在四种不同组成危废焚烧炉渣中的侵蚀行为及熔渣侵蚀前后砖中Cr(VI)的含量。结果表明,锆英石高温下分解形成单斜氧化锆和无定形的二氧化硅,促进化学稳定性较好的(Al,Cr)₂O₃固溶体的形成,提高了铝铬锆砖的致密化程度,同时改善了铝铬锆砖的抗渣侵蚀性能。此外,生成的二氧化硅可以还原砖中Cr(VI)化合物,降低铝铬锆砖中的Cr(VI)含量。熔渣侵蚀后,铝铬锆砖渗透层中Cr(VI)含量与熔渣成分密切相关。在被高碱性氧化物含量的熔渣侵蚀后,铝铬锆砖渗透层中的Cr(VI)含量较高,但锆英石作为氧化锆源的铝铬锆砖在不同熔渣中侵蚀前后的原砖层和渗透层内的Cr(VI)含量均低于欧盟限制标准。     

氧化铬加入量对出钢口填充料性能的影响

在填充料的常规配方中,分别添加质量分数为0、1％、2％、4％氧化铬,研究了不同氧化铬加入量对材料性能的影响。结果表明：氧化铬的引入明显提高了材料抗渣性能,但同时导致材料体积密度和强度略微降低,加入2％的氧化铬时,材料综合性能最好。     

Al2O3-SiC复相粉对Al2O3-SiC-C材料性能的影响

以电熔白刚玉(3～1、≤1、≤0.044 mm)、Al2O3-SiC复相粉(d50≤5μm)、α-Al2O3微粉(d50=1.2μm)、SiC粉(≤0.044 mm)、鳞片石墨(≤0.088 mm)、Si粉(d50=42.8μm)和B4C(d50≤10μm)为主要原料,热固酚醛树脂为结合剂,研究了分别用4%、8%、12%、16%质量分数的Al2O3-SiC复相粉等比例取代α-Al2O3微粉和SiC细粉对Al2O3-SiC-C试样在180℃固化后和1 000、1 500℃埋焦炭热处理后的显气孔率、体积密度、常温抗折强度、常温耐压强度、高温抗折强度(1 400℃)、抗热震性(1 100℃,水冷)以及抗氧化性(1 000、1 500℃)的影响。结果表明:随Al2O3-SiC复相粉加入量的增加,试样经180℃固化后常温性能下降,1 000℃热处理后常温性能变化不大,1 500℃热处理后除耐压强度显著提高外,其余各项常温性能变化不大;而高温抗折强度下降,抗热震性明显提高,试样经1 500℃氧化后的抗氧化性以加入4%质量分数复相粉的最佳。其原因可能是由于该复相粉的粒度更细,反应活性更高,其氧化层中更易生成莫来石,形成表面致密层从而有效地阻碍氧气向材料内部扩散。