RH真空处理过程中钢中氧含量预测模型

针对３００ｔ钢包ＲＨ真空处理低碳铝镇静钢的多次试验数据，建立了ＲＨ处理过程中钢中氧含量的定量预测模型，得到了钢中氧含量的预测公式，模型综合考虑了纯脱气时间，真空室吹氩流量，钢水环流量，钢包渣中ＦｅＯ＋ＭｎＯ含量，钢包内衬材质等因素的影响，并对改进ＲＨ操作进行了讨论。     

[C]、[O]和真空度对RH真空脱C的影响

ＲＨ装置上的脱Ｃ可分为表面脱Ｃ(即在钢液自由表面生成ＣＯ的反应 )、气泡脱Ｃ(即钢液环流用Ａｒ气泡吸收ＣＯ的反应 )和内部脱Ｃ(即钢液内部产生ＣＯ气泡的反应 )等三部分。在炼钢炉中将钢液粗脱Ｃ至 [Ｃ] =0 .0 2 5%～0 .0 6 5%后 ,不脱氧出钢至 2 50ｔ钢包并进行ＲＨ真空脱Ｃ处理。过程中除取样分析外 ,还记录了真空槽内压力 (即真空度 )随时间的变化。ＲＨ的相关参数为 :浸渍管径 0 .6ｍ ,下部槽内径 3.2ｍ ,到达真空度 1 33Ｐａ、环流恒定Ａｒ气流量 0 .0 5ｍ3 ｓ。从ＲＨ脱Ｃ处理中钢包钢液Ｃ浓度 (ＣＬ)随时间的变化得知 ,在初期和…     

连铸钢的可浇铸性和质量的改进

Ｆｅ－Ａｌ－Ｏ和Ｆｅ－Ａｌ－Ｃａ－Ｓ－Ｏ系的热力学基本原理对冶炼钙处理铝镇静钢是重要的,对此作了分析和讨论。为改善钙处理铝镇静钢的可浇铸性,要求脱氧产物的液态钙铝氧化物。对“液窗”进行了理论分析和试验研究,无论是否经过ＲＨ处理,出钢后保护渣的成分几乎没有变化。不过经脱气处理后渣的含氧量比未脱气的要低。发现在钢包处理时存在着一个“夹杂物途径”经过ＲＨ处理的炉次,其夹杂物途径明显区别于不作ＲＨ处理的炉次,并极大地影响钙处理效果。     

WF705在RH真空处理控制系统中的应用

攀钢于１９９８年初建成一套年处理钢水能力为５０万ｔ的ＲＨ真空处理装置。它的主要功能是：将从转炉出来的钢水进行脱氢、脱氧、脱碳及合金化。经过ＲＨ真空处理的钢水性能得到极大提高,从而可以提高攀钢冷轧薄板的产品质量。１控制系统的组成攀钢ＲＨ真空处理基础自动化控制系统采用西门子Ｓ５１５５ＵＰＬＣ,整个控制系统由ＰＬＣ１、ＰＬＣ２、ＯＭＳ１、ＯＭＳ２、ＬＥＶＥＬ２（二级计算机）、ＰＧ７６０构成,系统通过ＳＩＮＥＣＨ１网连接成一个整体。ＰＬＣ１控制真空处理部分,ＰＬＣ２控制合金加料部分。ＯＭＳ１、ＯＭＳ２…     

利用冶金废气生产碳化铁的热力学分析

根据热力学计算与分析，探讨气体成分，温度，压力以及析碳反应等对ＣＯ＋ＣＯ２＋Ｈ２＋Ｈ２Ｏ混合气体还原铁矿生经铁的影响，确定了利用冶金废气生产碳化铁的可能性。     

真空吹氧条件下RH传质的特点

在传输现象和能量平衡的基础上，建立了ＲＨ中流体循环流量与操作因素的关系式，描述了ＲＨ真空处理钢水循环流量的变化，为ＲＨ真空处理工艺实践提供了必要的技术依据。研究了真空条件下ＲＨ传质的特点，指出它的控制环节是液相传质，容量传质系数受反应气体分压、顶吹枪位、循环流量的影响，并且得出了它们之间的定量关系。     

宝钢一炼钢新建2RH真空脱气设施简介

简要说明了宝钢一炼钢新建２ＲＨ真空脱气设施的必要性,重点介绍了２ＲＨ采用的顶枪技术、真空系统、纯水闭路循环机械冷却水系统及ＥＩＣ三电一体化控制系统。新建的２ＲＨ真空脱气设施不仅脱碳、脱氢速度快,而且具有化学加热钢水、喷粉脱硫、喂丝吹氩等功能,真空槽可保持较高的温度,大大减少了槽内结冷钢的可能性。     

RH真空脱气槽下部用MgO-C砖的改进

作为在高温、减压操作条件下ＲＨ真空室下部所使用的内衬耐火材料而言 ,一般都是采用超高温烧成的直接结合镁铬砖 ,因而 ,要想大幅度提高其使用寿命确有困难。日本川崎炉衬耐火材料公司从节能、环保和提高ＲＨ脱气槽下部内衬使用寿命的目的出发 ,决定以ＭｇＯ -Ｃ砖取代原来所用的镁铬砖 ,收到了很好的效果。通过对传统ＭｇＯ -Ｃ砖的成分进行改进 (增加ＭｇＯ含量 ,降低Ｃ含量 ) ,提高了砖的抗热震性、抗氧化性以及抗渣性。实际使用结果表明 ,改进后的ＭｇＯ -Ｃ砖损耗速度仅为 0 6ｍｍ炉 ,使用寿命比原来的镁铬砖提高了 15 %RH真空脱…     

RH顶部喷粉工艺技术的开发

ＲＨ－ＰＢ（ＲＨ顶部喷粉）法是通过安装在ＲＨ中的顶部水冷喷枪，将粉状材料喷入到钢液中的一种新的精炼法。用这种方法，可以实现下列新的精炼功能：（１）喷吹ＣａＯ基助熔剂进行脱硫；（２）当钢中的碳＜２０ｐｐｍ时，向钢液内喷吹Ｆｅ２Ｏ３进行加速脱碳。     

氧化镧碳化行为的研究

用ＸＲＤ法对氧化镧与石墨粉在不同温度条件下反应产物的物相组成进行了鉴定，探讨了Ｌａ２Ｏ３与Ｃ作用生成稀土碳化物的反应历程。实验结果表明，在本实验条件下，Ｃ还原Ｌａ２Ｏ３要经历Ｌａ２Ｏ３→ＬａＣＯ→Ｌａ２Ｃ２Ｏ２→ＬａＣ３等反应阶段。同时，体系中ＣＯ分压的大小对反应产物的物相组成有较大的影响。     

真空条件下钢液脱气过程的模拟研究

基于相似的动力学机理,利用水溶液中溶解氧的去除过程模拟了钢液的真空脱气行为. 在负压25 kPa条件下发现,容器壁面或测氧探头表面会析出大量细小气泡,这一现象与以往脱气数学模型假设的内部脱气反应非常类似;为了验证内部脱气位点的存在,通过引入机械搅拌,对溶池表面和内部脱气速率进行了分析计算. 实验结果表明,在整个脱气过程中溶池表面脱气速率很低,内部脱气位点析出的气泡会极大地提高溶解氧的去除速率,尤其当真空压力为25 kPa时,其脱气速率约为自由表面的脱气速率的10倍,但内部反应仅局限于脱气的初始阶段,即高溶解氧浓度范围内. 另外,水溶液中溶解氧的去除为一级反应过程,其体积传质系数（k · A · V?1）为常数,因此可以利用溶解氧在水溶液中的去除过程模拟钢液的真空脱气行为. 为了描述真空压力和吹氩流量对k · A · V?1的影响,引入搅拌动能密度（ε）的概念,通过线性回归得到了lg (k · A · V?1)与lg ε之间的函数关系,并与以往的模拟研究进行了对比.      

Nitrogen Desorption in Molten Stainless Steel during Immersion Argon Blowing

The behavior of nitrogen desorption reaction in molten stainless steel for AISI 304 and 316 during immersion argon blowing through an immersed alumina nozzle with 3 mm in I.D. has been investigated by sampling method. Some kinetic parameters such as reaction order, rate constant and apparent activation energy of nitrogen desorption reaction for AISI 304 and 316 have been obtained. Results show that nitrogen desorption reaction from molten stainless steel for AISI 304 and 316 is the second order reaction. The rate constant at 1550 ℃ and 1580 ℃ for AISI 316 is 0.08407%-1·min-1 and 0.82370%-1·min-1, respectively. The rate constant at 1550 ℃ for AISI 304 is 0.4166%-1·min-1. The apparent activation energy Ea of nitrogen desorption reaction for AISI 316 is 2136.47 kJ/mol. This huge value of apparent activation energy verifies that the nitrogen desorption reaction has a complex and multistep reaction mechanism. The rate of nitrogen desorption reaction from molten stainless steel is mixed controlled by the desorption reaction of diatomic molecule nitrogen or of monatomic nitrogen from molten metal at the gas-metal interface and the mass transfer of nitrogen in molten metal. The rate equation of process for nitrogen desorption has been deduced.     

超纯轴承钢的精炼工艺

通过控制电炉(供氧强度、渣中氧化铁比例、出钢挡渣率、出钢钢液的氧活度)、钢包炉(精炼渣系、脱氧剂、钢液温度、精炼时间、底吹氩压力、精炼钢包耐火材料的选择、铁合金种类的选择)、真空脱气(真空度、真空时间、底吹氩压力)的工艺参数以及真空后的软吹氩搅拌、并采用IPAS系统和控制钢液浇铸速度,使超纯轴承钢(SFGCr15)的w(S)、w(Ti)、w(O)分别达到0.003%、0.001 2%和0.000 7%以下,钢中非金属夹杂物也处于较好水平,满足了国际顶尖轴承厂家对轴承钢的超纯要求.     

Modeling of gas-liquid reactions in ladle metallurgy: Part I. Physical modeling

A physical model of a ladle degassing operation was developed to simulate the reactions at rising bubbles and at the free surface. Carbon dioxide desorption from a sodium hydroxide solution was used to simulate the liquid-phase diffusion-controlled decarburization of liquid steel. It was found that under reduced pressure, the reactions were faster than attributable to solely the increase in volumetric flow rate. It was possible to separate the reactions with the bubbles from the free surface reactions; 20 to 40 pct of the reactions occurred at the free surface, depending on injection conditions. The free surface desorption rate depended on the gas flow rate and the number of injectors. The mass transfer coefficients to the bubbles were in reasonable agreement with previous work. Plume bending was observed when small bubbles were influenced by the bulk liquid flow patterns.     

Rate of nitrogen desorption from CaO-Al2O3 melts to gas phase

There is a limit to lowering the nitrogen level in steel, because of pickup from the atmosphere during and after degassing. Therefore, the nitride capacity of various fluxes has been measured in order to examine the possibility of nitrogen removal by using slag. It is necessary to take into account the nitrogen reaction rate between the gas and slag phases for the efficient removal of nitrogen in practical steelmaking processes. In this study, the nitrogen desorption rate from CaO-Al₂O₃ melts to gas phase has been examined at 1873 K. The mass-transfer coefficient of nitrogen in the melts increases as the CaO content increases, and the dependence is related to the viscosity of the melts. The reaction-rate constant of nitrogen desorption is found to be proportional to the 3/2 power of the oxygen partial pressure and increases as the CaO content increases under constant oxygen partial pressure.     

100 t单咀真空精炼炉底吹位置的优化

结合钢厂100 t单咀真空精炼炉相关参数,运用数值模拟的方法对脱气时单咀炉内的钢液流场进行了仿真计算,分析单咀炉内钢液流动的基本特征,研究了距底部圆心0.1～0.424 m吹气位置对钢液流场、钢液循环流量和混匀时间的影响。结果表明,原吹氩位置(距底部中心0.424 m),大部分氩气没有进入浸渍管,为避免氩气逸出,吹气孔距圆心应≤0.3 m;随吹气位置至圆心距离增大,钢水混匀时间减小,综合考虑钢液脱气效果和浸渍管寿命,最佳吹气位置应为距底部中心0.25～0.3 m处。     

Removal of hydrogen in the vacuum treatment of steel

The degassing of 09Г2C steel produced in an arc furnace and treated in a ladle–furnace unit at AO Uralskaya Stal is analyzed. The vacuum-treatment parameters that determine the effectiveness of hydrogen removal from the steel are identified: the depth and duration of vacuum treatment; the argon flow rate; the steel temperature; the thickness of the slag layer; and the free board in the vacuum chamber. The hydrogen content changes most significantly when the degassing time is increased to 20 min. Longer treatment is not recommended. The greatest effect of the residual pressure in degassing is observed with simultaneous decrease in the minimum pressure to 2 mbar. Vacuum treatment of the steel is considerably impaired with increase in the residual pressure. Hydrogen removal is improved with increase in the steel temperature to 1600–1620°C, but slows considerably at higher temperatures. The influence of the vacuum-treatment parameters is established quantitatively, and a regression equation is derived for predicting the results of hydrogen removal and selecting the parameter values corresponding to specified hydrogen content in the steel. Vacuum-treatment parameters that permit the economical production of steel with 2.1 ppm are determined: steel heating before vacuum treatment by 100–110°C; vacuum treatment for 20 min at a pressure no higher than 1.5 mbar in the vacuum chamber; argon flow rate 0.05 m³/t. The temperature losses of the metal are determined by the total treatment time, consisting of the active degassing time and the auxiliary time (the preliminary evacuation time), which depends on the capabilities of the equipment and the organization of the process. The minimum residual hydrogen content in the steel for the given equipment (1.6 ppm) is ensured by vacuum treatment for 40 min at a pressure no higher than 1 mbar in the vacuum chamber, with preliminary heating of the steel by 120–125 °C and with an argon flow rate up to 0.072 m³/t.     

Physicochemical grounds for the substitution of nitrogen for argon during out-of-furnace treatment of high-carbon steel

Physicochemical grounds for the possibility of replacing of argon with nitrogen during blowing a metal in the course of degassing and in a ladle-furnace unit are obtained using a mathematical model of degassing steel for out-of-furnace treatment. According to the data of examining the model for adequacy, the calculation error does not exceed 1%. A numerical experiment demonstrates that the replacement of argon with nitrogen during degassing of steel does not lead to any increase in the nitrogen content in it. Blowing in a ladle-furnace unit can be performed using an argon-nitrogen mixture taken in the proportion (2–3): 1. The replacement of argon with nitrogen allows the cost of the out-of-furnace treatment of steel to be decreased.     

Change of Nitrogen Content in the Molten Steel during CaO Powder Blowing

The rates of nitrogen desorption from molten steel were measured with the blow of CaO powder or argon gas onto the melts under reduced pressure. 15kg of electrolytic iron was melted in a MgO crucible by a high frequency induction furnace and the temperature of the melt was held at 1873 K. A mathematical model was developed with the consideration of the chemical reaction between sulphur in molten steel and CaO powder and the desorption of nitrogen at gas‐metal interface. The calculated results were in good agreement with the measured ones. The apparent rate constant of nitrogen desorption and the rate controlling step were examined.     

Rate of nitrogen desorption from liquid iron-carbon and iron-chromium alloys with argon

The rate of nitrogen desorption from inductively stirred liquid iron, iron-carbon, and iron-chromium alloys with argon carrier gas has been measured by the sampling method for a wide range of nitrogen, carbon, and chromium contents mainly at 1600 °C. The results obtained by the present work and other data of previous investigators are used to clarify the reaction mechanism of nitrogen desorption from liquid iron. The rate of nitrogen desorption from liquid iron and iron alloys is second order with respect to nitrogen content in the metal under the present condition, and mutual relationships among interfacial chemical reaction, liquid-phase mass transfer, and gas-phase mass transfer are elucidated. The effects of oxygen and sulfur on the rate of nitrogen desorption are given byk _' ^{c ’} = 3.15?_N ² [1/(1 + 300a₀ + 130a_s)]. Carbon dissolved in iron increases the rate of nitrogen desorption, and chromium decreases it. The effects of these alloying elements can be explained by the change of the nitrogen activity in the metal.