High Efficient Technology of Steelmaking With Low Silicon Hot Metal on Large Converter

To resolve the difficulty in slag formation during steelmaking with low silicon hot metal and to increase productivity, a new 5-hole lance was developed by increasing oxygen flow from 50 000 m^3/h to 60 000 m^3/h. Synthetic slag was added to adjust the slag composition. The problems such as difficulty in dephosphorization and slag adhesion to oxygen lance and hood were settled. Steel production and metal yield were increased and the nozzle life was prolonged through these techniques.

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 substitution 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.

Thermodynamic Study on BaO－BaF_2－Fe_xO Slags Used for Dephosphorization of Chromium－Containing Hot Metal

Electrochemical measurements of the solid-oxide galvanic cell, Mo|Mo+MoO2|ZrO2 (MgO)| Fe+ (FexO)+Ag| Fe, have been made at temperatures of 1473K and 1573K in order to obtain the activities of FexO in BaO-BaF2-FexO slags used for dephosphorization of chromium-containing hot metal. The FexO activities show a significant dependence upon the molar ratio of BaO/BaF2. Within the homogeneous liquid region, the substitution of BaF2 for BaO has an effect of raising the FexO activity. From these activity data, the phase diagrams of the system BaO -BaF2-FexO are drawn at 1473K and 1573K. The temperature dependence of the activity coefficient of FexO at a fixed BaO/ BaF2 molar ratio can be expressed by formula RTlnγ(FexO)=constant.

Distribution of Phosphorus between CaO-CaF2 Slag and Fe-C-P Melt

The equilibrium distribution ratio of phosphorus between CaO-CaF2 molten slag and Fe-C-P melt at 1450 ℃ was measured.The phosphate capacity of slag and the activity coefficient of phosphorus oxide were calculated.

Investigation on Steelmaking with Hot Metal Containing Low Silicon Content in Large Converter

There are some problems in steelmaking with hot metal containing low silicon content such as difficulty in slag formation, less slag for dephosphorization and slag adhesion on oxygen lance and hood. To overcome these problems, experiments wcrc conducted and some improvements were obtained, such as adding appropriate flux, increasing the lance position slightly during steelmaking and using effective multi-outlet nozzle. Moreover, to keep normal heating rate, the ore and scrap charge should be reduced due to less chemical heat input in steelmaking.

Wettability of Molten Steel/Na2O-Li2O-SiO2-B2O3 Slag System

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 CaF 2 in slag. The average desulphurization and dephosphorization rate is 68 83 % and 78 46 %, respectively. For molten steel, the substitution 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.

A Novel Technique for Determination of Flow Characteristics of Blast Furnace Slag

A study of flow characteristics of blast furnace slag helps determine its softening and flow (liquid-mobility) temperatures. The slag with a narrow difference between the two temperatures is termed a “Short Slag”. Its formation ensures higher rates of slag-metal reactions with the trickle of the slag soon after its formation exposing fresh mass for faster reactions, the trickling slag, creating fresh interfaces facilitating slag-metal exchanges. In the present work, a novel technique is adopted to determine the flow characteristics of blast furnace slag obtained from different industrial blast furnaces. It is seen that the results so obtained agree very closely with the values obtained from adopting conventional methods of determining the liquidus temperature using “slag atlas”. It is observed that under the range of compositions studied a high C/S ratio combined with a high MgO content in the slag is beneficial to the B.F. process as it renders a “short slag”.

Thermodynamic Behaviors of Nb and P in Dephosphorization of Niobium-bearing Hot Metal with BaO-based Slag

The Bayan Obo iron ore contains valuable metallic elements such as niobium and rare earth elements. However, developing appropriate metallurgical processes to achieve effective dephosphorization of Nb-bearing hot metal meanwhile retaining Nb in the steel products remains a challenge. We carried out a thermodynamic study on dephosphorization of Nbbearing hot metal and investigated the effects of the initial [C] content and the dephosphorization temperature on oxidation behaviors of [Nb] and [P]. In particular, we focused on thermodynamic analysis of dephosphorization of Nb-bearing hot metal with highly basic BaO-based slag. The results showed that the highly basic BaO-based slag system is more suitable for dephosphorization under oxidative conditions, and increasing the [C] content favors dephosphorization of Nb-bearing hot metal without oxidizing [Nb]. Moreover, the values of equilibrium oxygen activity for oxidation reactions of [Nb] and [P] are increased as the dephosphorization temperature increases. Considering the hot metal containing 0.02% of [Nb] in Baotou Steel, thermodynamic calculations indicated that the content of [P] can be reduced to 0.02%–0.05% and [Nb] remains unoxidized when dephosphorization occurs at the cconditions of T=1573–1673 K, [C]=4.0%, [Nb]=0.02%, aP2O5=10-24, aNb2O5=10-10.

Practice of Hot Metal Full Pretreatment and Less-slag Steelmaking in ShouGangJingTang

The hot metal full pretreatment and less-slag steelmaking process constituted a platform to produce clean steel with low cost and rapid pace and also realized a professional production line. The w[P] can be less than 0.030% at the end of De-P converter and 0.006% at the end of De-C converter. The w[N] in steel can be less than 15×10-6 at the stirring station. This production line can make clean steel steadily used for auto sheet or pipeline, for example X65 MS. The De-C slag was left in the converter for the next heat and recycled to De-P converter to reduce lime consumption, which has a great benefit for the cost saving.

Dephosphorization stability of hot metal by double slag operation in basic oxygen furnace

Double slag process was adopted to produce low-phosphorus steel from middle-phosphorus hot metal.To achieve a stable dephosphorization operation,conventional process was modified as follows：the blowing time was extended by approximately 1min by reducing the oxygen supply flow rate;calcium ferrite pellets were added to adjust the slag composition and viscosity;the dumping temperature was lowered by 30-50°C by the addition of calcium ferrite pellets during the double slag process to prevent phosphorus in the slag from returning to the molten steel;and the bottom-blown gas flow was increased during the blowing process.For 40 heats of comparative experiments,the rate of dephosphorization reached 91% and ranged between 87% and 95%;the phosphorus,sulfur,manganese,and oxygen contents calculated according to the compositions of molten steel and slag as well as the temperature of molten steel at the end-point of the basic oxygen furnace process were similar to the equilibrium values for the reaction between the slag and the steel.Less free calcium oxide and metallic iron were present in the final slag,and the surface of the slag mineral phase was smooth,clear,and well developed,which showed that the slag exhibited better melting effects than that produced using the conventional slag process.A steady phosphorus capacity in the slag and stable dephosphorization effects were achieved.

Performance of Low Fluoride Dephosphorization Slag of Hot Metal

The purpose of the study is to decrease content of CaF2 in dephosphorization slag. The dephosphorization effects of CaF2 replaced by B2O3 were investigated. The dephosphorization experiments were carried out at 1 450 ℃ in air atmosphere. The results show that the melting points and dephosphorization ratios change little when CaF2 was replaced by B2O3. The dephosphorization ratios are all greater than 80% and melting points can meet the requirement of hot metal pretreatment. Because of the change of alkalinity caused by B2 03, the oxidation of slag increases with increasing of B2 Oa contents. It is beneficial to pre-dephosphorization. As a result, for decreasing its pollution, CaF2 can be replaced by B2Oa to dispose fluoride-free pre-dephosphorization slag.

日钢大型高炉经济炼铁技术的应用效果

经济炼铁是基于系统集成的炼铁技术,运用经营理念指导炼铁生产实践,从而实现炼铁的经营目标。日钢根据自身的原燃料条件和技术经验,在新建3000m高炉时,对炉型设计充分优化,并创新性地把各系统先进技术进行集成应用,为高炉经济开炉及经济运行打下了良好基础。通过采取保障原燃料质量、控制合理的煤气流分布、活跃炉缸、优化渣相等措施,高炉实现了经济冶炼条件下炉况长期稳定顺行,生铁成本优势明显。2023年1-8月,对比沿江沿海25家钢企同类高炉综合生铁成本,日钢大型高炉生铁成本领先82元/t。

宝钢BRP技术的研究与开发

介绍了宝山钢铁股份公司开发BRP技术的背景,阐述了宝钢BRP技术开发的试验条件和试验结果,分析了脱磷与炉渣碱度、底吹强度、停吹温度的关系,并讨论了底吹、渣中全铁、铁水硅的质量分数对脱磷的影响。宝钢BRP技术的生产实绩表明,脱磷炉的脱磷率达到84%以上,磷的质量分数平均低于0 015%,脱碳炉的脱磷率达到58%以上,平均停吹磷的质量分数低于0 006%。

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措施,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。

1600℃高碱性渣与钢液间磷的分配比

在实验室电阻炉的条件下,对复吹转炉在吹炼含中高磷铁水时冶炼终点最佳炉渣成分进行了研究.研究结果表明,炉渣的氧化铁质量分数在15%左右,炉渣碱度在4 4,其他成分具有一定配比时,炉渣的脱磷能力较强.讨论了光学碱度对中高磷铁水脱磷的影响,回归出如下的1600℃终渣磷分配比的计算公式:lgLp=0 52Λ-0 0027w(FeO)+0 49.式中,Lp为磷在渣与金属中的分配比;Λ为多元渣系的平均光学碱度;w(FeO)为渣中FeO的质量分数.

大型转炉低硅铁水炼钢研究

针对转炉低硅铁水炼钢成渣困难,渣量少不利于脱磷,容易产生粘枪、粘烟罩等问题,在吹炼过程中加入适量熔剂,枪位稍高于正常含硅铁水炼钢,设计化渣效果好、喷溅少的多孔喷头。低硅铁水炼钢化学热减少,可减少矿石、废钢用量,保证熔池金属正常的升温速度。低硅铁水炼钢可以实现少渣炼钢,有利于减少石灰消耗和提高金属收得率。

非均相铁水脱磷剂研究现状

对铁水预处理非均相脱磷剂的研究现状进行了文献综述。为了弄清CaO为基体的非均相渣的热力学性质,运用电子探针微量分析技术、电化学技术测定了CaO-P2O5-FexO三元系及FexO-CaO-SiO2-P2O5和CaO-P2O5-CaF2-FexO四元系中液固共存区液相的化学组成与P2O5和FexO的活度,计算了铁水中磷的平衡浓度。发现了采用非均相脱磷剂降低渣量和CaF2用量的可能性。讨论了开展非均相脱磷剂等高效铁水脱磷剂研究的重要意义。

大型转炉低硅铁水高效吹炼的研究

为了解决转炉低硅铁水炼钢化渣困难和提高转炉钢产量,设计了新的5孔喷头并使氧流量由5万m3/h提高到6万m3/h。在炼钢过程中加入合成渣,调整炉渣成分。解决了低硅铁水炼钢粘枪、粘烟罩、脱磷困难等问题。增加了钢产量,提高了金属收得率,延长了喷头寿命。

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。

鞍钢铁水脱硫扒渣发展综述

为了满足生产低硫高附加值产品的需要,铁水预处理作为钢铁冶金生产工艺的一个重要手段,越来越得到业内人士的认同,特别是铁水炉外脱硫扒渣近年来发展较快。介绍鞍钢铁水脱硫扒渣发展的3个阶段及扒渣工艺设备的优化与改进情况;对国产脱硫工艺设备、美国ESM复合喷粉脱硫工艺设备以及德国POLYSUIS复合喷粉脱硫工艺进行了全面的对比分析。鞍钢铁水脱硫扒渣发展过程充分实践了鞍钢“高起点、少投入、快产出、高效益”的技改方针。