返回转炉钢渣对铁水脱硅、脱磷的影响

在实验室条件下，模拟转炉钢渣的组成，利用CaO-SiO2-Fe2O3-MnO2-MgO-P2O5-Al2O3-CaF2系熔剂对铁水进行预处理，研究了转炉钢渣组成和渣中添加BaO对铁水脱硅和脱磷的影响。结果表明，通过控制转炉钢渣的组成可获得约75％的脱硅率和80％左右的脱磷率。脱硅过程伴随有铁水的回磷反应。随Fe2O3含量增加，回磷率提高，最大回磷率可达22．5％。此外，分析了铁水回磷原因和防止回磷的，发现使用添加BaO的转炉钢渣对脱硅后的铁水进行脱磷处理，当BaO添加量控制在15％－20％范围内时，可明显提高铁水的脱磷率。     

用预熔渣对铁水脱磷的试验研究

以铁水和脱磷粉剂为研究体系,应用CaO-Fe2O3-CaF2渣系的脱磷粉剂和其预熔渣对铁水脱磷,研究结果表明,用Al2O3和白云石部分替代萤石,预熔后的脱磷渣都比未预熔渣的脱磷速度快,且二者的处理过程结果基本相似,脱磷粉剂经过预熔处理,成渣迅速,预处理时间缩短,温降小,脱磷率高。     

转炉渣用于铁水脱磷的试验研究

在实验室利用转炉渣配制的铁水脱磷剂进行铁水预脱磷试验，测定了脱磷剂组成等因素对脱磷率的影响。结果表明：在铁水脱磷前[Si]≤0．15％条件下，当脱磷剂中转炉渣配比为80％时，相应铁水脱磷率约为78％；Fe2O3和BaCO3代替转炉渣的合适替代量分别约为5％和10％；脱磷剂中（P2O5）含量的增加会导致脱磷率的显著降低，其影响关系式为：ηp（％）=84．01—4．60（P2O5％）。     

转炉渣用于铁水预脱磷的工艺实验

 研究了转炉渣剂的组成及相关工艺因素对铁水脱磷率的影响。结果表明：为降低转炉渣的熔化温度以适应铁水预处理温度的要求，转炉渣的CaF2添加量应控制在15%~20%；采用80%的转炉渣和20%的CaF2配制的转炉渣剂对铁水进行脱磷处理时，脱磷率可达到78%左右；另外，转炉渣剂中的P2O5能显著降低铁水脱磷率。     

利用转炉渣对铁水脱磷的动力学

在实验室条件下，模拟转炉渣组成，利用CaO-SiQ-Fe2O3-MnO2-MgO-P2O5-Al2O3-CaF2系熔剂对铁水进行脱磷预处理。实验发现：随着预处理时间的延长，铁水发生回磷反应。在铁水回磷状态下，测定了磷在渣中的传质系数。讨论了回磷原因和抑制铁水回磷反应的措施。在此基础上，确定了合适的铁水脱磷预处理时间和转炉渣的优化组成。     

梅钢中磷铁水低磷钢冶炼问题的探讨

 梅钢铁水中磷含量偏高,冶炼低磷钢种有困难,通过对国内外降磷方法所采用的“铁水炉外预脱磷”、“SRP法”及“转炉双渣法脱磷方法”的比较分析,摸索出适合梅钢自身特点的方法——转炉同炉铁水脱磷炼钢工艺。通过在冶炼中采用前期造渣、中途倒渣的方法,将磷的质量分数降到≤0.01％,满足了生产低磷钢的要求。     

转炉渣在铁水脱硅领域的应用研究

在实验室及工业大牛产条件下采用宝钢转炉渣作熔剂配制脱硅剂进行铁水脱硅实验。结果表明：用转炉渣替代石灰作熔剂生产脱硅剂脱硅效果更佳;脱硅剂中转炉渣(质量分数)在15％～30％的范围内时,脱硅剂具有良好的脱硅效果和经济效益。     

低碱度渣铁水预处理脱磷研究

低碱度渣铁水预处理脱磷的一个主要特点是形成高氧势、低碱度炉渣.实验选用炉渣碱度1.3～1.8,(ω)(TFe)为20%～25%,底搅强度大于0.20 m3/(min·t),对4.0%(ω)(C)-(0.1%～0.3%)(ω)(P)-0.4%(ω)(Si)的铁水进行铁水脱磷预处理.实验表明,低碱度渣能稳定获得200左右的脱磷分配比,脱磷率大于90%.同时对供氧参数和底吹强度对低碱度渣脱磷的影响进行了相应的讨论.     

Investigation on Dephosphorization of Stainless Steel

In the scale of ironmaking and steelmaking, the dephosphorization can be divided into four classes. The first level which is known very well by metallurgists is the dephosphorization for carbon steels and low alloy steels. The second level is that included in the pretreatment process of hot metal. It differs from the first level as it must consider how to treat the selective oxidation of ［P］ and ［C］. Furthermore, The contradictory of dephosphorization and desulphurization has to be harmonized. The third level is that for high alloy steels and the fourth is that for ferroalloys. In these cases, two technical ways either oxidizing dephosphorization or reducing dephosphorization can be selected. Whether which one is chosen, the key problem is to lower down phosphorous content efficiently meanwhile to keep the concentration of Cr and/or Mn almost lossless. 　　The cheapest raw materials for the production of high alloy steel are the returning scrap of that steel. Raising the proportion of the returning scraps in the total amount of raw materials is a very important measure to decrease the production cost. In order to avoid an obvious oxidation of Cr, Mn and so on during that melting process it is impossible to adopt the oxidational dephosphorization procedures which is generally carried out in the production of low alloy steel. In this case, after returning several times the phosphorous content in the scraps is accumulated. And then it gradually approaches to the level specified in the standard of the steel. Finally, it will become a waste. It was estimated that the market demand on high alloy steels as stainless steels would rapidly grow. So the scraps containing low phosphorous is urgently needed in a great deal. 　　On the other hand, the standards of some high alloy steels, which are designated for extremely severe environment only, allow a very low phosphorous content. For example, it is claimed that W［P］<0.015 %—0.020 % if the stainless steel products will contact with urea or nitric acid. If the resistance to corrosive fatigue and welding crack is highlighted the phosphorous content should be decreased to less than (100—50)×10－4 %. And Koros P J et al estimated that dephosphorous to 14×10－4 % will be wanted［1］. 　　So far no technology for dephosphorization of stainless steels can be widely adopted in industrial scale. This will be one of the major research projects in the coming century. This paper devotes to a discussion on the strategy of oxidational dephosphorization and the improvement of the reductional dephosphorization.     

Double Slag Operation Dephosphorization in BOF for Producing Low Phosphorus Steel

A study on the production of low phosphorus steel by double slag operation in 210 t converter was carried out. A phosphorus content of less than 0.005% (mass percent) was obtained before tapping. About 80% phosphorus could be removed by the first slag after 5 min. High Fe³⁺ content and high basicity in the first slag were in favor of dephosphorization. On the other hand, Fe³⁺ content had less effect on dephosphorization during second slag treatment. In the second slag period, the fraction of dephosphorization increased with the increase of basicity up to a basicity of 6. Further increase of basicity of the second slag had very little effect on dephosphorization. The tapping temperature had great impact on dephosphorization. It was impossible to get phosphorus less that 0. 005% when the tapping temperature was higher than 1 943 K. The optimum operation conditions were suggested. On the basis of these conditions, the amount of the second slag and the effect of the remaining first slag were estimated.     

转炉渣中氧化磷对铁水脱磷影响的研究

以转炉渣为基础渣,在实验室测定了CaF2、P2O5质量分数变化对转炉渣熔点的影响。依据测定结果,利用转炉渣配制适合铁水脱磷要求的脱磷剂进行了铁水预脱磷实验,结合相关的转炉脱磷研究结果,分析了脱磷剂中P2O5对脱磷的影响,提出了对最终外排炉渣中的质量分数要求。在1350 ℃温度条件下,w（P2O5）＝166％转炉渣为基础的脱磷剂,对预脱硅处理后的铁水,脱磷剂加入10％时可取得约77％的脱磷率。脱磷剂中w（P2O5）＜75％时可取得60％以上的脱磷率。     

Utilization of Multiphase Fluxes for the Dephosphorization of Hot Metal

Although steelmaking slags have been usually treated and studied as homogeneous liquids, they are actually mixtures of a liquid and solids in practical processes. CaO‐based refining flux that does not contain fluxing agents such as CaF₂ inevitably forms a heterogeneous slag in normal cases, and hence, it is defined as a “multiphase flux.” Efficient utilization of this type of flux would decrease the consumption of resources and the emission of CO₂, and thus, would reduce the load on the environment. Metallurgical studies on multiphase fluxes are limited, however, the physical chemistry and reaction kinetics of the same are important for the development of advanced refining processes. The reaction mechanism of dephosphorization using a multiphase flux at hot metal temperatures was investigated in this study. The reaction of a P₂O₅‐containing slag with solid CaO was studied by immersing a CaO disc in the slag. A CaO‐FeO layer was formed near the interface, and a solid solution of Ca₂SiO₄‐Ca₃P₂O₈ was observed in this layer. The Fe‐P‐Si alloy reacted with calcium ferrites at 1673 K, and the samples were analysed by XMA. The same solid solution (Ca₂SiO₄‐Ca₃P₂O₈) was observed near the slag‐metal interface, which suggests that the phosphorus removed from the metal gets concentrated in the solid phase. The experimental results were reproduced with a kinetic simulation model. The simulation program was also applied to the reaction of the CaO‐FeO droplet in a hot‐metal bath.     

Effect of Modification Treatment for Reduction of Dephosphorization Slag in Hot Metal Bath

To extract the valuable elements from the steel slag, a novel approach has been proposed by modification treatment to provide the stronger driving forces and accelerate the reduction. Three types of dephosphorization steel slags were reduced using carbon-saturated iron bath to extract iron and phosphorus simultaneously. During the process of reduction, slag composition, temperature, and original P2O5 content were investigated respectively. Slag modification treatment, adding either silica or alumina to vary the slag composition, was proven to accelerate the reduction of dephosphorization slag. The equilibrium time can be shortened from 60 to 30 min. Slag modification also allowed the reduction reaction to occur at lower temperature. After slag modification, the original P2O5 content in slag presents a slight difference on reduction process. Almost half of the reduced phosphorus was vaporized within 5 and 20 min. As more and more FeO was reduced, CO gas generation decreased, and evaporation amount of phosphorus therefore decreases.     

液渣成分和硅酸二钙颗粒含量对铁水预处理非均相脱磷剂脱磷能力的影响简

 高磷铁水预处理脱磷的难题是脱磷剂用量太大、温降太多，急需研究脱磷能力强的脱磷剂。含有固体颗粒和液渣的非均相脱磷剂比仅含液渣的均相脱磷剂的脱磷能力强很多。为此，针对磷的质量分数为0. 5%的高磷铁水，应用FactSageTM热力学软件优选出脱磷能力强的3种液渣，添加不同数量的硅酸二钙颗粒配制非均相脱磷剂试样，脱磷剂和熔铁在1560℃下反应6h，测定熔铁中的平衡磷含量，用以评价其脱磷能力，然后在1400℃下进行了铁水脱磷预处理试验。研究结果表明，随着硅酸二钙颗粒含量的增加，非均相脱磷剂的脱磷能力明显改善；采用非均相脱磷剂有助于减少渣量和控制反应器内衬的侵蚀；采用非均相脱磷剂对铁水脱磷，仍然需要控制较高的渣铁界面FetO浓度。     

铁水包脱磷工艺研究

研究在铁水包内喷吹CaO粉剂、顶加氧化铁皮及同时喷吹氧气的铁水脱磷反应。通过测定实际生产过程中脱磷渣的磷平衡分配比及其它组成物成份和相关工艺参数,计算出脱磷渣的磷容量,进而分析了铁水硅含量、温度、脱磷渣碱度及氧化铁等成份对该脱磷工艺的影响。     

Study on Kinetic Model for Dephosphorization of High-Phosphorus Hot Metal Pretreatment

Focused on the hot metal pretreatment process in the torpedo-car and based on the powder injection metallurgy principle, a kinetic model for dephosphorization of high-phosphorus hot metal pretreatment was developed. The validity of this model was verified by comparison between the experimental results in laboratory and the calculated results. The influences of dephosphorization capacity of molten slag and technological conditions on the dephosphorization efficiency were calculated by applying the model. The results show that lower temperatures are favorable to dephosphorization, CaO content in slag should be controlled at about 50%, suitable initial phosphorus content in the hot metal with higher phosphorus contents is about 0.35% by comprehensively considering various factors, slag systems of higher iron oxide content and higher basicity have higher capacity of dephosphorization.     

Vacuum Treatment for Simultaneous Desulphurization and Dephosphorization of Hot Metal and Molten Steel

The vacuum treatment for simultaneous desulphurization and dephosphorization of hot metal and molten steel with pre-melted CaO-based slag was carried out. For pre-treatment of hot metal, both desulphurization and dephosphorization are improved with the increase of CaO in slag, but deteriorated with the increase of CaF2 in slag. The average desulphurization and dephosphorization rate is 68.83% and 78.46 %, respectively. For molten steel, the sub-stitution of BaO for CaO in slag has minor effect on simultaneous desulphurization and dephosphorization. The desulphurization and dephosphorization rate is higher than 90 % and 50% respectively with the lowest final sulfur and phosphorus mass percent being 0. 001 2 % and 0. 010%, respectively. The overall effect of simultaneous desulphurization and dephosphorization of molten steel is better than that of hot metal.     

含转炉渣的预熔脱磷剂进行铁水脱磷实验

在实验室条件下,用部分转炉渣代替预熔脱磷剂中纯化学试剂原料进行铁水预处理脱磷实验研究,研究发现,含有转炉渣的预熔脱磷剂能实现较好的脱磷效果;在1350℃,加入量为10％的条件下,含转炉渣45.73％的预熔脱磷剂能将铁水中的磷由0.21％降低到0.011％,脱磷率可达到94.76％。     

酒钢转炉改造过程中铁水脱硅工艺的设计

酒钢为满足不锈钢冶炼时铁水脱磷的工艺要求,在其转炉大型化改造过程中,采用了高炉铁水沟机械式投撒脱硅剂的方法进行铁水预脱硅。介绍了酒钢铁水预脱硅工艺的设计、主要设备及控制方法等。     

320t鱼雷罐脱硫工艺铁水回硫因素控制

为改善转入炉铁水回硫现状，结合320t鱼雷罐铁水脱硫生产工艺，就鱼雷罐铁水温度，鱼雷罐二次出铁，鱼雷罐内口粘渣，铁水装入量，脱硫喷吹时间，脱硫后铁水等待时间等相关因素进行系统全面分析，提出合理的控制措施，旨在不断完善脱硫工艺操作参数，减轻转炉的冶炼压力。