包钢低硅烧结矿铁酸钙生成特性的影响因素

 为了探明白云鄂博低硅烧结矿中铁酸钙生成特性的影响因素，在红外烧结炉中，通过改变最高烧结温度、烧结配料的碱度、MgO含量、CaF2含量、SiO2含量、铝硅比，对以自产精矿为主要含铁原料的烧结试样，进行了单因素多水平正交微型烧结试验。研究结果表明，不同因素对烧结试样粘结相强度的影响存在不同趋势：随着最高烧结温度、碱度、wSiO2的提高，烧结试样的粘结相强度呈现增加趋势；随着wMgO、wCaF2、wAl2O3/wSiO2的降低，烧结试样的粘结相强度呈现出开始变化不明显，之后又下降的趋势。当最高烧结温度为1280℃、碱度为28、MgO含量(质量分数，下同)为10%、CaF2含量为08%、SiO2含量为44%及铝硅比为015时，微型烧结试样的粘结相强度最高。各影响因素中粘结相强度最佳的烧结矿矿相组成中赤铁矿和复合铁酸钙(SFCA)所占比例不完全一致，但二者之和均较高；SFCA通常为针柱状、片状或颗粒状，并与赤铁矿、玻璃相或磁铁矿交织成网络结构。     

Formation Characteristics of Calcium Ferrite in Low Silicon Sinter

 Influence of sintering temperature, basicity and MgO content on the formation characteristics of calcium ferrite in low silicon sinter of Baotou Iron and Steel Company was studied by means of mini-sintering test and mineralographic microscope analysis. In addition, the suitable sintering parameters such as temperature and basicity were explored. The results found that optimum temperature for the formation of calcium ferrite is 1280 ℃, the basicity of 25-28 is helpful to the development of acicular or columnar calcium ferrite, and MgO content in the low silicon sintering raw materials should be lower than 28% because MgO can intensively inhibit the formation of calcium ferrite. And calcium ferrite in the sinter belongs to calcium ferrite with low calcium, which is different from that in ordinary sinter at home and abroad. So, it provided theoretical basis for promoting formation of calcium ferrite in low silicon sinter and improving properties of sinter.     

Effect of Nickel on Formation Mechanisms of Silico-ferrite of Calcium and Aluminum (SFCA)

Under the pressures of both the decrease of high-grade high-quality iron ore resources and the increase of raw material costs,the iron and steel enterprises in China turn to adopt iron ores which contain special elements such as nickel,manganese,etc.in the sintering blend.Analytical reagents were used for sintering experiments,and the sinters were analyzed with X-ray diffraction,scanning electron microscopy and mineralogical microscopy to study the effect of nickel on the silico-ferrite of calcium and aluminum(SFCA)bonding phase formation during sintering.The results indicated that SFCA was divided into nickel-containing and nickel-free areas due to the presence of nickel.The increasing content of nickel would greatly reduce the content of SFCA and promote the formation of calcium aluminum silicate.A great deal of Fe2O3 participated in the crystal transition to Fe3O4,reducing the amount of Fe2O3 involved in the formation of calcium ferrite.When the blending ratio of NiO,which is used to provide the nickel in the sintering process,is less than 3%,the calcium ferrite is in substantially interleaving corrosion with hematite and magnetite.Both the porosity and silicate glass phase content are low,which contributes to the sintering production.     

Effects of Compound Silicate Gangue on Formation of Complex Calcium Ferrite During Sintering Process

 In order to improve the quality of sinter produced by Baiyunebo iron ore concentrate, the effects of compound silicate gangue containing kalium and natrium on formation of complex calcium ferrite were studied using mini-sintering test device, optical microscope (OM) analysis and scanning electron microscope (SEM)/energy dispersive X-ray spectroscopy (EDX) analysis. The results show that with the increasing of K2O and Na2O content in sintering samples, K2O and Na2O highly enriched in the glassy phases, the contents of complex calcium ferrite and hematite in sinter decreased and the porosity increased; the mineral microstructure exhibited large cavities and thin framework and became inhomogeneous. The compound silicate gangue containing kalium and natrium significantly inhibited the generation of complex calcium ferrite (SFCA). When the content of K2O and Na2O was higher in samples, a part of K2O and Na2O entered into complex calcium ferrite, which caused the fine grains of SFCA with acicular and columnar to agglomerate into coarse grains, and its bonding effect to iron oxides reduced. The content of K2O and Na2O in sinter had effects on quantity, composition and morphology of complex calcium ferrite.     

准化学平衡条件下MgO对多元铁酸钙生成的影响

 研究了不同碱度、不同SiO2与Al2O3含量条件下MgO对铁酸钙生成的影响以及Fe2O3 SiO2 CaO Al2O3 MgO系内烧结矿的成矿过程,通过模拟高碱度烧结矿配料在空气气氛、1220 ℃准化学平衡条件下进行烧结实验,利用XRD QAMS法进行矿物定量、显微镜下观察矿相结构等方法进行分析。实验结果表明：R=2.0、不含Al2O3时增加MgO含量铁酸钙生成量明显增多,加入质量分数为25%的Al2O3后,MgO促进铁酸钙生成的作用减弱,Al2O3改变了MgO对铁酸钙生成的影响规律;随着碱度从1.8增加到2.3,铁酸钙生成量呈上升趋势,但是MgO对铁酸钙生成的促进作用减弱;实验还发现,随着MgO含量增加,不含Al2O3时铁酸钙晶形有“柱状”向“针状”变化趋势;加入质量分数为2.5%的Al2O3后,MgO含量增加对铁酸钙晶形影响减小。     

高铁低硅烧结技术研究

高铁低硅烧结矿固结机理与普通高碱度烧结矿不同,它是铁酸钙液相固结与铁氧化物再结晶或重结晶固相固结并存.采用一整套与高铁低硅烧结矿相适应的技术,如理想的碱度制度、合理的料层高度、较低的配碳量、添加优质活性石灰及调整烧结矿中的MgO和Al2O3等,在保证利用系数的情况下,获得了高强度、高还原性的烧结矿.     

Al_2O_3、MgO交互作用对复合铁酸钙生成影响机理

为了探索复合铁酸钙的生成机制以优化烧结工艺,提高烧结矿质量,采用相平衡法研究了准化学平衡条件下Al_2O_3与MgO在烧结中的行为。结果表明,Al_2O_3和MgO的共同存在有利于复合铁酸钙(silico-ferrite of calcium and alminum,简称SFCA)的生成,但存在着交互作用,MgO促进赤铁矿分解生成磁铁矿,Al_2O_3的存在可抑制MgO的作用,减少磁铁矿生成,尤其在Al_2O_3质量分数较高时,MgO促进磁铁矿生成能力降低,促进SFCA生成作用增强。当MgO质量分数为2%时,添加质量分数2%的Al_2O_3矿相中磁铁矿质量分数快速降低,SFCA质量分数快速增加;随着Al_2O_3质量分数升高,SFCA晶面间距减小,晶体结构稳定性增强,有利于SFCA的生成;Al_2O_3质量分数超过3%后,孔洞结构增多,SFCA质量分数增加变缓,磁铁矿质量分数呈降低趋势,赤铁矿质量分数有升高趋势。     

Effects of Temperature and Atmosphere on Sintering Process of Iron Ores

 The relationship of time to minerals composition in sinters is investigated by mineragraphy are claritied observation and component analysis, and the effects of temperature and atmosphere on mineralization process. Results are obtained as follows. The initial melt forms below the eutectic temperature of CaO·Fe2O3 and CaO·2Fe2O3, which is complex substance containing Ca, Fe, Si and Al, rather than the binary calcium ferrite melt. Minerals composition of binding phase is related to local content of silica in melt, which is influenced by temperature. Appearance of the melt promotes the transition from hematite to magnetite, which then alters the mechanism of calcium ferrite formation. Before the formation of magnetite, the contents of Fe and Ca within the multiple calcium ferrite decrease with temperature, but in the case of magnetite presence, the content of Fe increases solely with increase of temperature and decrease of oxygen potential. Temperature and atmosphere determine minerals composition together, and bring influence on sintering process in different ways. It can be deduced that temperature affects kinetics of the mineralization process, but atmosphere just plays a role in thermodynamics.     

碱度对烧结矿液相形成性能和微观结构特性的影响

摘要：采用Factsage 7.1热力学软件模拟计算了碱度对烧结矿液相形成性能和微观结构特性的影响,并开展了不同碱度的烧结杯试验研究。研究表明：随着碱度增加,烧结矿理论液相生成量增加,液相黏度降低,液相中Fe2O3/CaO增加,铁酸钙形成条件改善。当碱度为1.95时,铁酸钙含量最高,CaO与Fe2O3结合形成稳定的铁酸钙粘结相,有利于减少Fe2O3发生还原粉化现象;而继续提高碱度至2.05时,颗粒较粗的褐铁矿和赤铁矿与CaO进一步接触、矿化,使烧结矿赤铁矿含量升高,铁酸钙和磁铁矿含量减少,液相黏度降低,孔隙率增大,烧结矿结构均匀性变差,导致烧结矿基体组织结构抵抗还原过程中产生的晶格畸变能力变差,粉化严重。综合考虑碱度对烧结矿转鼓强度和低温还原粉化性能的影响,在试验所用烧结原料条件下,烧结矿适宜碱度应控制为1.95。     

焊剂碱度对管线钢埋弧焊熔敷金属显微组织和韧性的影响

研究了焊剂碱度对管线钢时弧焊熔敷金属显微组织和韧性的影响。结果表明：随焊剂碱度的提高,焊缝中锰、钛含量产加,而氧、硅含量降低,同时具有有利于针状铁素体形核的夹杂物尺寸和分布,促进了奥氏体晶粒内针状铁素体的形成,提高了熔敷金属的低温冲击韧性。     

Al-Ti�����Էǵ��ʸ���MnS������Ϊ����֯��Ӱ��

The morphology, composition and sizes of MnS containing inclusions in a non-quenched and tempered steel containing 0. 35% of carbon deoxidized with different contents of aluminium and titanium were investigated. The generation of acicular ferrite in austenite grain for the samples with different carbon content was observed on line with a cooling speed of 2??/s after 10min heating at 1350?? by a confocal laser high temperature scanning microscope. The results show that aluminum content in the steel more than 0. 04% is not beneficial to the formation of fine, disperse and spherical MnS. Adding 0. 02% Ti to steel could form the complex inclusions of MgO-Al2O3-TiOx-SiO2-MnS which is fine, dispersed and spherical when the aluminum content in the steel is low. The complex inclusions of MgO-Al2O3-TiOx-SiO2-MnS are beneficial to the generation of acicular ferrite in the non-quenched and tempered steel. Carbon content effects the generation of acicular ferrite in Ti-deoxidized non-quenched and tempered steel, after C-addition, the ration of acicular ferrite would decrease in Ti-deoxidized steel.     

铝硅比对烧结成矿特性及冶金性能的影响

Al2O3和SiO2是复合铁酸钙的重要组分,适宜的铝硅比是获得良好烧结成矿特性和冶金性能的重要条件.基于某钢厂现场烧结原料结构,运用FactSage理论计算了烧结体系的平衡物相组成及液相组分变化规律,随着铝硅比由0.41降至0.34,烧结矿中液相、铁氧化物等优质物相含量增加,尖晶石等劣质物相含量下降,且液相中析出复合铁...     

添加水化铁酸钙拜耳法新工艺溶出规律及机理研究

在添加水化铁酸钙的条件下系统进行了溶出中低品位铝土矿试验,结果表明,随水化铁酸钙添加量增多,溶出赤泥铝硅比、钠硅比降低;随配矿量减少、溶出温度升高、溶出时间延长,溶出赤泥铝硅比降低。在温度260℃,时间60 min,使用水化铁酸钙添加剂,得到了赤泥铝硅比为0.74、钠硅比为0.24的较好溶出结果。通过对溶出赤泥进行衍射、扫描电镜和能谱分析,表明赤泥中硅矿物以铁取代铝的水化石榴石为主,Al2O3的饱和系数为0.2左右,Fe2O3的饱和系数为0.7左右,SiO2饱和系数接近1,硅矿物组成改变是赤泥铝硅比和钠硅比降低的原因。     

铁酸钙的形态对烧结矿抗断裂性能的影响

采用维氏压痕试验法,研究了含有不同形态铁酸钙的烧结矿中裂纹的萌生与扩展,考察了铁酸钙的形态对烧结矿抗断裂性能的影响.结果表明:铁酸钙尺寸较大时,烧结矿的抗断裂性能由铁酸钙本体的断裂韧性决定,它的尺寸较小时由其形态决定;铁酸钙的晶粒越细,致使裂纹萌生的临界载荷越大,烧结矿的抗断裂性能越好.烧结生产中生成细晶粒铁酸钙有利于提高烧结矿的抗断裂性能.     

Al_2O_3/SiO_2对低温烧结成矿规律的影响

研究了混合料 Al2 O3/Si O2 对低温烧结时烧结矿成矿规律的影响 ,揭示了低温烧结时铁酸盐的矿物含量、化学成分、结晶状态、成矿特性等的内在变化规律 ,指出调整混合料 Al2 O3/Si O2 是钒钛磁铁精矿实现低温烧结的前提条件     

Effect of Magnesium on Inclusion Formation in TiKilled Steels and Microstructural Evolution in Welding Induced CoarseGrained Heat Affected Zone

 Effects of Mg on the chemical component and size distribution of Ti bearing inclusions favored grain refinement of the welding induced coarse grained heat affected zone (CGHAZ), with enhanced impact toughness in Ti killed steels, which were examined based on experimental observations and thermodynamic calculations. The results indicated that the chemical constituents of the inclusions gradually varied from the Ti O+Ti Mg O compound oxide to the Ti Mg O+MgO compound oxide and the single phase MgO, as the Mg content increased from 0002 3% to 0006%. A trace addition of Mg (approximately 0002%) led to the refinement of Ti bearing inclusions by creating the Ti Mg O compound oxide and provided favorable size distribution of the inclusions for acicular ferrite transformation with a high nucleation rate in the CGHAZ, and a high volume fraction of acicular ferrite was obtained in the CGHAZ with enhanced impact toughness. Otherwise, a high content of Mg (approximately 0006%) produced a single phase MgO, which was impotent to nucleate an acicular ferrite, and a microstructure comprised of a ferrite side plate and a grain boundary ferrite developed in the CGHAZ. The experimental results were confirmed by thermodynamic calculations.     

12CaO·7Al2O3炉渣与合金钢液的反应

 12CaO·7Al2O3炉渣组成为w(SiO2)=6%,w(Al2O3)=46%,w(CaO)=48%,与合金结构钢钢液进行了实验室试验。结果表明,该渣具有很高的碱度,90 min反应结束后钢中w(TO)=0000 6%~0001 3%,w(S)=0000 4%~0001 0%。同时得出为控制钢中总氧含量应将炉渣碱度控制在9左右,钢中生成的夹杂物大都是低熔点、球状、尺寸很小的钙镁铝硅酸盐类夹杂物,这类夹杂物能够避免钢材产生各向异性,并且在轧制时能够稍许变形,能够提高钢材的抗疲劳性能。     

化学成分对铁酸盐烧结液相流动性的影响

铁酸盐液相是高碱度烧结矿固结的基础,适宜的流动性有利于烧结液相有效黏结和保证料层透气性。为了明晰化学成分对其液相流动性的影响,采用微型烧结法研究了Fe2O3与CaO的摩尔比为1.0、1.5和2.0时铁酸盐的液相流动特征,以及SiO2对这3类铁酸盐液相流动性的影响规律,在此基础上,探讨了促使高流动性铁酸盐生成条件下烧结原料中黏附粉化学成分的选取原则。结果表明,铁酸盐液相流动性随其中CaO量的增加而升高;随着SiO2含量的增加,摩尔比为1.0的铁酸盐液相流动性呈现先增加后降低的趋势,且在高硅低碱度下仍具有较高的流动性;摩尔比为1.5的铁酸盐液相流动性变化规律与高钙铁酸盐相似,但SiO2的质量分数大于5.5%、二元碱度低于3.26时,液相流动性则降低;摩尔比为2.0的铁酸盐液相流动性随SiO2含量的增加呈单调降低趋势。     

含铝铁酸钙CFA的生成行为

 含铝铁酸钙(CFA)是生成复合铁酸钙(SFCA)的一种重要前驱化合物,为了揭示CFA的生成路径和反应机理,采用压块-焙烧法并结合XRD和SEM-EDS等检测方法,研究不同烧结温度下CaO-Al₂O₃-Fe₂O₃三元系中的矿相生成和元素迁移规律。CFA生成行为研究结果表明,首先在低温条件下(＜750 ℃)生成铁酸二钙(C₂F),升温至800~950 ℃时C₂F与Fe₂O₃反应生成铁酸一钙(CF),然后在900~950 ℃的烧结温度区间内Al₂O₃与CaO反应生成铝酸半钙(CA₂),并在CF-CA₂-Fe₂O₃三元界面处开始生成CFA,最终对CA₂形成了具有针状结构的CFA产物包裹层。     

奥氏体化温度对Ti–Zr处理钢中针状铁素体转变的影响

Ti、Zr的复合氧化物可以有效诱导针状铁素体形核,从而细化晶粒。为了研究Ti–Zr处理钢中针状铁素体转变机理,使用25 kg真空感应炉中熔炼试验所需钢种,向低合金钢中添加了质量分数为0.038%钛和0.008%锆。利用高温激光共聚焦显微镜原位观察了奥氏体化温度对针状铁素体转变行为的变化,使用扫描电镜观察了Ti–Zr处理钢种的夹杂物成分和针状铁素体在夹杂物表面形核,使用光学显微镜观察不同奥氏体化温度下的微观组织变化差异。结果表明,随着奥氏体化温度从1250 ℃增加至1400 ℃,奥氏体晶粒尺寸从125.6 μm 增加至279.8 μm,针状铁素体开始转变温度和侧板条铁素体开始转变温度先增加,在1350 ℃条件下达到最大值,后又降低,针状铁素体的体积分数由39.6%增加至83.6%;Ti–Zr处理钢中核心为Zr–Ti–O,外部为Al–Ti–Zr–O的氧化物为核心表面析出MnS的复合氧化物主要集中在1.5～3 μm,可以有效促进针状铁素体形核,贫Mn区和夹杂物与铁素体之间的良好晶格关系为该型夹杂物能够促进针状铁素体形核机理。奥氏体晶粒尺寸的增加导致多边形铁素形核位点的减少和针状铁素体的形核空间的增加,钛锆复合处理形成大量的有效诱发针状铁素体形核的夹杂物,这共同导致了针状铁素体体积分数增加。