掺铬铁渣的铝镁系浇注料的制备与性能研究

为了综合利用生产高碳铬铁合金时产生的铬铁废渣,采用50%(w)的电熔镁砂颗粒、41%(w)的电熔镁砂粉+铬铁渣粉、5%(w)的高铝水泥、4%(w)的硅微粉制备了掺加铬铁渣的铝镁系浇注料,并研究了掺加不同量铬铁渣粉(镁砂粉与铬铁渣粉的质量比分别为0 10、1 10、2 10和3 10)的该浇注料经1 200℃3 h烧后的线变化率、体积密度、显气孔率、常温抗折强度、常温耐压强度、抗热震性和抗渣性。结果表明:掺加41%(w)铬铁渣的铝镁系浇注料经1 200℃3 h烧后的综合性能最佳,其常温耐压强度可达55 MPa,抗热震性和抗渣性良好。     

利用炭素铬铁渣制造锰铁包衬用耐火材料

以相图为理论依据,在炭素铬铁渣中加入烧结镁砂研制出碱性耐火材料,用于砌筑锰铁包衬,使用寿命是原镁砖内衬的两倍     

耐火原料及其产品的化学成分研究

本文选取辽宁省本地生产的96个耐火材料样品进行研究,分析了耐火原料轻烧氧化镁、电熔镁砂和烧结镁砂及成品镁钙砖和镁铬砖的化学组分,为新型耐火材料的生产和应用研究打下理论基础.     

影响镁碳耐火材料表面MgO致密层形成的因素

研究了镁碳耐火材料中镁砂原料的种类和碳含量 ,渣剂的有无及碱度 ,炉内气氛以及是否加铝脱氧等因素对镁碳耐火材料表面MgO致密层形成的影响。结果表明 :(1)在w(C) =10 %～ 2 0 %范围内 ,随着碳含量的降低 ,形成的MgO致密层越完整 ,且厚度增加 ;(2 )Mg(g)氧化形成MgO致密层的氧是由熔渣通过熔融金属提供的 ,凡是影响熔渣和熔融金属中氧活度的因素 ,都会对MgO致密层的形成产生影响 ;(3)炉内气氛对MgO致密层的形成没有明显的影响 ;(4)与电熔镁砂相比 ,使用烧结镁砂为原料时 ,耐火材料表面更容易形成MgO致密层。     

沥青结合镁炭砖的生产

为了降低炼钢用耐火材料的成本，目前钢铁工业以探求两种耐火材料选用方案，一是选用价格较低、寿命较短的耐火材料；二是选用高价格、长寿命的耐火材料。本文所论述的以沥青为主要结合剂的镁炭砖正是从第一方面着手。1原料选择镁砂：镁砂中MgO含量对镁砂颗粒在熔渣中及有熔渣渗入时的熔损行为有很大影响。从镁砂的质量与成本这两方面综合考虑，选用镁砂MS91。其中MgO＞gi％，SIO。＜4．5％，CaO＜1．6％，灼烧减量＜0．3％，真密度23．549·cm‘。石墨：石墨的纯度直接影响着砖的抗渣性，纯度较低的石墨，灰分中大量存在SIOZ，这降低…     

镁砂加入量及粒度对铬渣砖性能的影响

为了改善以铝热法冶炼金属铬所得的铝铬渣为主原料所制铬渣砖的抗热震性,研究了高纯镁砂的加入量和粒度对铬渣砖的常温性能和抗热震性的影响。结果表明:与不加高纯镁砂的铬渣砖相比,在铬渣砖中引入高纯镁砂,可以提高试样的抗热震性,当高纯镁砂以2~1 mm的形式引入,且加入量为3%(w)时,经1 450℃烧后铝铬砖的抗热震性最好,而且常温耐压强度不会大幅降低。     

Cr_2O_3对方镁石－尖晶石耐火材料抗渣性的影响

采用电熔镁砂及预合成电熔ＭＡ砂为原料，在高温下烧成方镁石－尖晶石试样，当加入少量铬矿时可提高其热震稳定性及抗渣性。用坩埚法作富ＣａＯ转炉渣对方镁石－尖晶石系耐火材料的侵蚀试验后，采用ＸＲＤ、ＳＥＭ、ＥＤＡＸ、岩相分析等方法分析Ｃｒ_２Ｏ_３对方镁石－尖晶石耐火材料抗渣性的影响。     

利用差热分析法预测镁碳质耐火材料的使用寿命

马格尼托哥尔斯克钢铁股份有限公司在生产洁净钢时,采用不烧的镁碳质耐火材料砌筑转炉车间的盛钢桶内衬。作为此种耐火材料的原料,采用低硅的烧结镁砂或电熔镁砂。通常采用各种牌号的石墨(坩埚石     

轻量化耐火材料的研制与应用

基于"骨料微孔化、基质紧密化"的研究思路,采用显气孔率低、闭口气孔率高、热导率比普通耐火材料低20％～50％、抗渣性能与普通原料相当的具有微纳米尺度晶内气孔的微孔刚玉和矾土以及镁砂为原料,根据颗粒紧密堆积理论,对Dinger-Funk方程进行修正,建立轻量耐火材料基质堆积密度预测模型,制备了轻量铝镁浇注料.结果表明:此...     

生产含MgO92%～95%镁砂的资源保护性工艺

简要叙述了萨特卡矿床镁石的性能，以及利用原料二步煅烧生产的镁砂的工艺，列举了关于煅烧产品的质量及生产碱性耐火材料用镁砂的经济技术指标的数据，列举了煅烧产品的ＭｇＯ提纯结果及苛性镁砂的元素分析，在降低向大气中排放废物及降低生产制品用原料单位消耗的前提下，原则上在萨特卡公司有可能实施二步煅烧法。     

Degradation of low‐carbon MgO‐C refractory by high‐alumina stainless steel slags in VOD ladle slagline

A new type of low‐carbon magnesia carbon refractory (LCMCR) substituting for MgO‐Cr₂O₃ refractory was successfully used in vacuum oxygen decarburization (VOD) ladle slagline, and the composition and microstructure of the used LCMCR were investigated. The results indicated that the decarburizing reaction (MgO‐C reaction) in the LCMCR under the VOD refining condition (high temperature, low pressure) was inhibited due to the low carbon content in the MgO‐C refractory and the dense layer formed between slag and original layer. The dense layer prevented the penetration of the external O₂ into the LCMCR inside because of the lower permeability of this layer, and thus, the direct burnout of the C in the LCMCR was substantially restrained. On the other hand, the large size crystal and the ultra‐low inclusions (SiO₂ and Fe₂O₃) content of the fused magnesia in the LCMCR made the magnesia more slag resistance, because the grain boundary in magnesia had higher slag penetration resistance and the contact area between the slag and the magnesia was reduced. The two aspects of the inhibited decarburizing reaction and the high quality magnesia synthetically contributed to the high slag resistance of the LCMCR.     

TiO_2对镁铬砖抗渣蚀性的影响

利用XRD分析和光学显微镜等测试手段 ,研究了添加TiO2 对镁铬砖抗渣蚀性的影响。结果表明 :炉渣中的CaO能分解镁铬砖中的二次尖晶石而使镁铬砖损毁 ,但加入TiO2 后 ,TiO2 能优先于尖晶石中的Cr2 O3与渣中CaO反应 ,生成高熔点的CaTiO3,从而抑制CaO对砖中镁铬尖晶石的分解 ,提高了镁铬砖的抗高钙渣渣蚀能力     

Investigation of slag-refractory interactions for the Ruhrstahl Heraeus (RH) vacuum degassing process in steelmaking

In order to determine the effect of slag composition during the RH process on refractory wear, magnesia–carbon and magnesia–chromite refractories were immersed for 10 min at 1600 °C in a ladle slag, two FeO-rich slags (20 and 40 wt% FeO) and two CaO–Al₂O₃ slags. Corrosion of magnesia–carbon refractory by the ladle and CaO–Al₂O₃ slags was limited as the refractory carbon phase efficiently prevented slag infiltration. Severe degradation was observed in contact with FeO-rich slags. FeO oxidized the carbon phase with formation of Fe droplets at the hot face. Regarding magnesia–chromite refractory, the corrosion mechanism consisted of severe slag infiltration, high temperature inactivation of the secondary chromite and primary chromite dissolution in the infiltrating slag. The FeO-rich slags seem to have generated more severe conditions as the infiltrating slag pushed apart the periclase grains, leading to severe refractory erosion. The degradation mechanisms are discussed by combining experimental results and thermodynamic calculations.     

Corrosion Resistance Mechanism of Magnesia Zirconia Brick to RH Furnace Slag

Magnesia zirconia brick containing 11 wt% zirconia was prepared with magnesia and monoclinic zirconia as starting materials in order to replace the chrome-containing materials for RH furnace.The corrosion resistance of magnesia zirconia brick and fused rebonded magnesia chrome brick (short for magnesia chrome brick) to high and low basicity slag of RH furnace was comparatively researched by rotary slag method and their slag resistance mechanisms were analyzed.The results show that:(1) because the reaction l...     

Three bond modes of basic refractories used for Ruhrstahl Heraeus degassing process

Magnesia–spinel brick and unburnt periclase–spinel–Al brick are being employed as a substitution of traditional magnesia–chrome brick in the chromium-free campaign of lining materials in Ruhrstahl Heraeus (RH) degasser. These three materials are investigated, in terms of physical properties, corrosion resistance and flexibility by wedge splitting test. Tracking their physical alterations and chemical reactions through burning or heating, three bond modes are discovered. Magnesia–chrome brick is subject to a series of phase transformation with rising temperature to yield a liquid envelop around chromite-ore particles, to further form porous rim while liquid is gradually absorbed by surrounding magnesia and eventually to precipitate secondary chromite spinel lied between magnesia particles by thoroughly dissociating chrome ore. The precipitated chromite spinel functions as the featured bond that enhances hot strength and corrosion resistance to slag, and additionally liquid coexistence improves the flexibility. The direct bond mode of magnesia particles in magnesia–spinel brick endures slag penetration by immanent character of MgO. Spinel incorporation in magnesia effectively improves thermal shock resistance. Due to minor negative value of permanent linear change after reheating, further sintering (densifying) in using at high temperature would bring a risk of loosening and open joints of magnesia–spinel lining. While used in RH degasser, unburnt periclase–spinel–Al bricks undergo a miraculous process of metallic Al melting, gaseous AlN and AlON formation, MgAlON whiskers germination combined with gaseous Mg reduced, and micron-size whisker network bond domination in their matrix. Such a whisker-network bond renders the material a successful eco-friendly alternative to magnesia–chrome refractory.     

Slag Resistance of Refractories for Direct Reduction of Laterite Nickel Ores in Rotary Kilns

Aiming at prolonging the service life of refractories for direct reduction of laterite nickel ores in rotary kilns, the slag resistance of ten materials(corundum bricks, chrome corundum bricks, silicon nitride bonded silicon carbide bricks, high alumina silicon carbide bricks, high alumina bricks, magnesia chrome bricks, magnesium aluminate spinel bricks, spinel chrome corundum bricks, chrome corundum castables and magnesia alumina chrome composite spinel bricks) was evaluated by rotary slag tests, which simulate the service conditions in rotary kilns. The corroded residual bricks were analyzed by SEM and EDS. The results show that the magnesia alumina chrome composite spinel brick possesses the advantages of magnesium aluminate spinel bricks and chrome corundum bricks; MgO-rich spinel can absorb the penetrated ferric oxide, and forms a dense zeylanite layer, which prevents the penetration of the molten laterite nickel ores; therefore, it is an ideal lining of rotary kilns for direct reduction of laterite nickel ores.     

Improvement of Durability of Purging Plugs Using MgO Micropowder for Refining Ladles

To modulate the matrix of purging plugs, MgO micropowder was introduced as a replacement to magnesia powder in alumina–magnesia castables, and the effect of MgO micropowder on the properties of alumina–magnesia castables and the possibility of developing chrome‐free castables were investigated. Experimental results showed that the introduction of MgO micropowder resulted in an improvement in the volume stability, strength, and thermal shock resistance of alumina–magnesia castables due to its high surface energy and small particle size. However, excessive amounts of MgO micropowder led to a lower densification, and there was a slight degradation in the performance of the alumina–magnesia castables. The slag resistance of the prepared alumina–magnesia castables was significantly better than that of the alumina–chrome castables. Microstructure and energy spectrum analysis showed that the formation of a solidified reaction layer, mainly consisting of spinel and CaAl₁₂O₁₉, was the major cause of the observed difference in slag resistance. In addition, the alumina–magnesia castables had a lower linear thermal expansion coefficient than that of the alumina–chrome castables at each experimental temperature, which effectively decreased the thermal stress during its service period, thus exhibiting good thermal shock resistance.     

Investigation of shaped alumina based refractories used in slagging gasifiers

Gasifiers are containment vessels used to react a carbon feedstock with oxygen and water in order to produce synthetic gas. During the gasification process the refractory liner protects the gasifier shell from high temperatures and pressures, corrosive slag, thermal shock and thermal cycling. However the performance of the currently used high chrome oxide materials does not meet the service requirements of industry, so there is a demand of new chrome oxide free materials. Compared to the sintering atmosphere the mechanical properties, phase formation as well as the resistance against thermal shock and alkali-corrosion of shaped alumina based refractories have been evaluated. According to the results potential candidates for further studies including reducing sintered β-alumina, spinel, hibonite and slag-stone.     

Investigation of slag containing refractory materials for gasification processes

In gasification processes the reaction of carbon feedstocks with oxygen and water leads to production of synthetic gas. The development of a new gasification technique reduces the temperature at the liner wall in the range of 1300 °C. Thus, the currently used high chrome oxide based materials can be replaced by new chrome oxide free materials fulfilling economical as well as ecological aspects. In this contribution the performance of alumina castables with different brown coal ash-contents (slag containing refractory materials) and sintered in different atmospheres have been investigated according to their thermo-mechanical properties, phase formation as well as resistance against thermal shock and corrosion attack under gasification-similar conditions. The slag containing refractory material with 11 wt.% brown coal ash sintered in reducing atmosphere has shown the best results with regard to mechanical properties and corrosion resistance and will be a promising liner material for gasification processes up to 1400 °C.