铁水预处理温度下CaO—SiO2—FeO—P2O5—CaF2渣系中CaO饱和溶解量

对１３００℃和１３５０℃的铁水预处理温度下ＣａＯ－ＳｉＯ２－ＦｅＯ－Ｐ２Ｏ５－ＣａＦ２渣系中ＣａＯ饱和溶解量进行了测定。实验结果表明，温度升高对提高ＣａＯ饱和溶解量有利，渣中ＣａＦ２，ＦｅＯ含量增加，ＣａＯ饱和溶解减少，当渣组成们于ＣａＯ＋Ｌ和Ｌ交界上时，与其它区域相比，ＣａＯ达到饱和所需溶解时间最短。     

铁水预处理温度下CaO－SiO_2－FeO－P_2O_5－CaF_2渣系中Ca

对１３００℃和１３５０℃的铁水预处理温度下ＣａＯ－ＳｉＯ＿２－ＦｅＯ－Ｐ＿２Ｏ＿５－ＣａＦ＿２渣系中ＣａＯ饱和溶解量进行了测定。实验结果表明，温度升高对提高ＣａＯ饱和溶解量有利；渣中ＣａＦ＿２、ＦｅＯ含量增加，ＣａＯ饱和溶解量减少；当渣组成位于ＣａＯ＋Ｌ和Ｌ交界上时，与其它区域相比，ＣａＯ达到饱和所需溶解时间最短。     

复合脱硫剂中钙的物相分析

利用脱硫剂试样与水反应生产的乙炔通过氧燃烧，生成的ＣＯ２用碱石棉吸收，重量法测定碳量，计算ＣａＣ２含量；用丙三醇－乙二醇－蔗糖－水混合浸取剂浸取游离ＣａＯ和ＣａＣ２，用ＥＧ－ＴＡ在ｐＨ大于１２时测定ＣａＯ和ＣａＣ２合量，将合量减去ＣａＣ２量计算游离ＣａＯ含量；浸取后残渣用乙酸浸取ＣａＣＯ３，用ＥＧＴＡ络合滴定法测定钙量计算出ＣａＣＯ３含量；最后的残渣用硫酸－盐酸－硼酸－水浸取分析ＣａＦ２。     

CaO—CaF2—SiO2渣系碳酸盐容量和硫化物容量的关系

根据文献报道１４７３－１７７３Ｋ的ＣａＯ－ＣａＦ２－ＳｉＯ２渣系碳酸盐容量和１４７３－１６２３Ｋ硫化物容量的数值，考查了ＸＣａＯ、ＸＣａＯ／ＸＳｉＯ２、ＸＣａＯ／（ＸＳｉＯ２＋ＸＣａＦ２）、（ＸＣａＯ＋ＸＣａＦ２）／ＸＳｉＯ２及光学碱度五种表达炉渣成分的参数与碳酸盐和硫化物容量的关系，研究了该渣系碳酸盐容理和硫化物容量的关系，结果表明：碳酸盐容量与ＸＣａＯ／ＸＳｉＯ２，（ＸＣａＯ＋ＸＣａＦ２）／Ｘ     

磷在CaO—BaO—CaF2渣系与锰铁熔体间的平衡

通过ＣａＯ－ＢａＯ－ＣａＦ２渣系和Ｆｅ－Ｍｎ－Ｃ－Ｐ熔体间的平衡分配实验，研究了ＢａＯ、ＣａＦ２、温度及锰铁中碳、锰含量对磷、锰平衡分配的影响，并计算了ＣａＯ－ＢａＯ－ＣａＦ２渣系的磷酸盐容量及Ｐ２Ｏ５的活度系数。     

BaO—CaO—Na2O—CaF2—Cr2O3渣系的不锈钢脱磷

测定了１５００℃时磷在ＢａＯ－ＣａＯ－Ｎａ２Ｏ－ＣａＦ２－Ｃｒ２Ｏ３渣子和０．１２Ｃ－０．７１Ｓｉ－１８Ｃｒ不锈钢熔体之间的分配比，试验结果表明，该渣系的不锈钢脱磷能力比ＣａＯ基渣好，与ＢａＯ基渣相当。     

磷在CaO－BaO－CaF_2渣系与锰铁熔体间的平衡

通过ＣａＯ－ＢａＯ－ＣａＦ２渣系和Ｆｅ－Ｍｎ－Ｃ－Ｐ熔体间的平衡分配实验，研究了ＢａＯ、ＣａＦ２、温度及锰铁中碳、锰含量对磷、锰平衡分配的影响，并计算了ＣａＯ－ＢａＯ－ＣａＦ２渣系的磷酸盐容量及Ｐ２Ｏ５的活度系数．     

高速钢W6Mo5Cr4V2的脱磷试验

在３０ｋｇ感应炉上用ＣａＯ－Ｎａ２ＣＯ３－ＣａＦ２－ＦｅｘＯ（ＭｏＯ３）渣、ＭｏＣｌ６粉剂和Ａｌ－Ｃａ合金作脱磷剂对高速钢Ｗ６Ｍｏ５Ｃｒ４Ｖ２进行脱磷试验。结果表明，ＣａＯ－Ｎａ２ＣＯ３－ＣａＦ２－ＦｅｘＯ渣的脱磷效果最好，一般脱磷率可达２６％￣５６％。     

CaCO3在钢铁冶金过程中作用方式探讨

本文结合ＣａＣＯ３在钢铁冶金过程中应用的典型技术与工艺，对ＣａＣＯ３作用机理进行了分析，认为ＣａＣＯ３分解形成ＣＯ２穿过界面层形成搅拌是其有别于一般喷粉冶金的一个重要方面。     

β—2CaO·SiO2的水化及与CO2的反应

研究了β－２ＣａＯ·ＳｉＯ２于稀碱液水热条件下的水化及与ＣＯ２的反应，最终反应产物为ＣａＣＯ３，ＳｉＯ２ｎＨ２Ｏ。当溶液中ＳｉＯ２浓度处于上升阶段所形成的ＣａＣＯ３包裹ＳｉＯ２·ｎＨ２Ｏ的团粒结构，其料浆的流动性最佳。     

Preparation and Metallurgical Analysis of High Activity Burnt Lime for Steelmaking

Burnt lime is an important material in steelmaking and its activity degree is a key factor for liquid steel quality.The burnt lime was made by the calcination of limestone in a high pressure electric furnace.The burnt lime mineralogical phases and micro-morphologies were characterized by X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM).The burnt lime activity degree was determined by acid-base titration,the burnt lime pore distribution was measured by mercury intrusion porosimetry(MIP),and the thermal effect of a mixture of burnt lime and slag was measured by differential scanning calorimetry(DSC).The results showed that the CaO grain size and pore size of burnt lime made under high pressure were larger than those of burnt lime made under atmospheric pressure.The CaO grain size and pore size increased and the laminate phenomenon also occurred clearly under high pressure.The activity degree of burnt lime made under high pressure was greater than that made under atmospheric pressure.The maximum activity degree was 437 mL for burnt lime made under a pressure of 0.4 MPa.For the same ratio of CaO to SiO_2,the melting temperature,hemisphere temperature and fluidity temperature of slag decreased with increasing burnt lime activity degree.The higher the activity degree the burnt lime had,the better the slag forming occurred.It was advantageous for 2CaO·SiO_2and 3CaO·SiO_2 forming at lower temperatures if the burnt lime activity degree was increased.     

石灰质量对炼钢的影响及其质量控制

简述了石灰质量对炼钢的影响并探讨了其质量控制措施。活性度和CaO含量高而硫含量、杂质含量和灼减低的石灰可降低炼钢用的石灰消耗并提高钢水质量以及冶炼水平。通过选用优质原料并控制合理的粒度、长径比，采用气体燃料和采用水洗料等措施可以获得高质量石灰。     

微波煅烧石灰的活性度及显微结构

 试验选取3个不同产地的石灰石为原料,研究了微波加热以及不同结构的石灰石对石灰活性度的影响,并对活性石灰的微观形貌进行了观察。试验结果表明,利用微波加热可在较低的加热温度和较短的保温时间条件下得到高活性的石灰,所得石灰的活性度均达到了400 mL以上,最高可达435 mL,比传统生产石灰的方法活性度要高25 mL;当石灰石的结构致密且晶粒大小分布不均匀时,所得石灰的活性度偏低;通过扫描电子显微镜对石灰的观察可以更清楚了解到活性石灰的微观形貌为多孔结构,由细小的氧化钙晶粒组成。     

铁水预处理低成本生产实践

为了降低铁水预处理成本,对铁水预处理过程参数进行优化,包括喷粉速率、喷枪插入深度等参数,并且在不影响脱硫效率的前提下,采用低CaO含量的钝化石灰粉替代高CaO含量的钝化石灰粉进行喷吹脱硫尝试。结果表明,钝化石灰粉消耗减少0.963 kg/t铁,镁粉脱硫效率提高6.9%,低CaO含量的钝化石灰粉不影响脱硫率。     

Dissolution of Lime in Synthetic ‘FeO’‐SiO2 and CaO‐‘FeO’‐SiO2 Slags

Dissolution of different CaO samples into molten synthetic ‘FeO’‐SiO₂ and ‘FeO’‐SiO₂‐CaO slags was carried out in a closed tube furnace at 1873 K. The slag was kept stagnant. It was found that the dissolution rate was very fast when CaO rod was dipped into ‘FeO’‐SiO₂ slag. In the case of ‘FeO’‐SiO₂‐CaO slag, the dissolution of CaO rod in the stagnant slag was retarded after the initial period (2 minutes). Only less than 16 percent CaO reacted with the slag, irrespective of the type of lime. Three phase‐regions were identified in the reacted part of the lime rod by SEM‐EDS analysis. The formation of these regions was explained thermodynamically. A dense layer of 2CaO · SiO₂ was found to be responsible for the total stop of the dissolution. It could be concluded that constant removal of the 2CaO · SiO₂ layer would be of essence to obtain a high dissolution rate of lime. In this connection, it was found necessary to study the dissolution of lime in moving slag to reach a reliable conclusion regarding the relevance of the reactivity obtained by water ATSM test to the real reactivity of lime in high temperature slag.     

残留CO2对石灰在转炉初渣中溶解的影响

 在转炉炼钢过程中,石灰快速溶解对转炉高效脱磷具有十分重要的意义,石灰溶解过程中熔渣/石灰界面处形成的2CaO·SiO₂产物层被认为是阻碍石灰溶解的关键因素。制备了具有两种不同CO₂含量的部分煅烧石灰石,采用浸泡法研究了部分煅烧石灰石在转炉初渣中的溶解行为,并与纯石灰、石灰石的溶解行为进行比较。结果表明,石灰石溶解时在液态熔渣中CaO的传质系数为石灰的2.1倍,残留CO₂质量分数为10%的部分煅烧石灰石的传质系数高达石灰石的6.7倍。在CO₂质量分数为0～43.5%时,石灰的溶解速率先增大后减小。石灰溶解过程中形成的2CaO·SiO₂层严重阻碍了FeO_x的扩散,从而减缓了石灰的溶解。与石灰不同,石灰石分解产生的CO₂能够破坏2CaO·SiO₂层并破坏自身结构,有利于熔渣的渗透,这也适用于残留CO₂的部分煅烧石灰石。制备纯石灰的过程中为了确保石灰芯部完全煅烧,因此极易导致石灰外表面发生过烧,而制备部分煅烧石灰石能在一定程度上解决表面过烧的问题。此外,与石灰石相比,部分煅烧石灰石由于表面是石灰外壳,溶解初期其表面附近的炉渣温降相对更低,能够避免溶解初期出现停滞阶段。在转炉富余热量有限的情况下,部分煅烧石灰石的石灰替换比高于石灰石,这取决于部分煅烧石灰石中的CO₂残留量。     

脱硫剂粒度对铁水脱硫的影响试验

 通过不同粒度脱硫剂的铁水脱硫试验,结合实际生产中脱硫渣微观结构的分析,探讨了脱硫剂粒度对铁水脱硫的影响。结果表明,随着脱硫剂粒度的减小,铁水脱硫量、脱硫率和脱硫速率常数均随之增大。脱硫渣结构分为3层：外层主要为脱硫产物CaS,厚度为10~50μm;中间层主要为2CaO·SiO2;内核为未反应的CaO。粒度越小,石灰颗粒利用率越高。为保证较好的脱硫效果和提高利用率,建议将脱硫剂粒度控制为0.5~1.5mm。     

Production and properties of burnt lime coated with dicalcium ferrite

Abstract

Ferruginous lime is the term applied to burnt lime (CaO) coated with dicalcium ferrite (2CaO.Fe₂O₃). Its high degradation strength, its resistance to hydration, and its capacity for fast and complete solution of fluxes in the basic oxygen and electric arc furnaces make it extremely attractive as a steelmaking flux. The objectives of the present work were to assess the feasibility of producing ferruginous lime in a rotary kiln type reactor, and to determine the operating conditions favourable for both the formation of a hydration resistant product and the minimisation of problems such as accretions and agglomerations within the reactor. With respect to processing conditions, the trials suggested that ferruginous lime be generated using a peak reaction temperature of 1260°C and allowing 45 min at greater than 1200°C. The optimal oxide addition is 10% by weight of the limestone charge to the rotary lime kiln. When subjected to short duration hydrating conditions, i.e. 30 min in contact with steam at 100°C (according to ASTM specification X6), the ferruginous lime product exhibited good resistance to hydration (relative to pure CaO) and moderate physical degradation. Laboratory tests demonstrated the significantly enhanced rate and degree of dissolution of ferruginous lime (compared with uncoated lime) in a steelmaking slag.     

A Dynamic Flux Dissolution Model for Oxygen Steelmaking

A modified model for prediction of flux dissolution in oxygen steelmaking process is presented in this study. The aim of this paper is to introduce a procedure for simulating the amount of dissolved lime with respect to the saturation concentration of CaO by coupling the existing thermodynamic and kinetic models simultaneously. The procedure is developed to calculate the saturation concentrations/solubility of CaO in slag using thermodynamic models namely FactSage?, Cell Model, and Thermo-Calc?. Total amount of dissolved lime is evaluated by integrating solubility values in the rate equation of lime dissolution over time taking into account the effects of physical properties and temperature of slag and particle size of flux additions and validated against industrial data available in literature. Comparison between measured and calculated undissolved lime shows a good agreement between them using any thermodynamic models even though there are some differences in the predictions of saturation concentration of CaO in slag. It has been shown that two distinct control mechanisms for lime dissolution in BOF slags exist and consideration of the free lime-controlled mechanism is essential for accurate prediction of dissolution rate of lime in slag.