复吹转炉炼钢过程机理模型

在分析复吹转炉冶炼过程机理的基础上，应用冶金热力学、动力学、传输原理和反应工程学理论，建立了描述冶炼过程的动力学模型，确定了模型的有关参数。模型的关键在于正确找出转炉冶炼过程中各氧化反应的限制环节，建立氧化反应速度与限制环节速度的联系，从而得到转炉中各氧化反应的速度方程。     

复吹转炉炼钢过程脱碳模型

通过分析复吹转炉脱碳过程的冶金机理,应用冶金热力学、动力学和传输理论,建立描述转炉脱碳过程的动力学模型,确定了模型的有关参数.模型的关键在于正确计算并比较钢液中[C]和[O]的传质速度,找到转炉冶炼脱碳过程的限制环节,并通过一系列热力学计算得到进入钢液的氧在各元素间的分配比例,从而得到转炉中脱碳反应的速度方程.将模型应用于本钢150 t转炉冶炼过程,模型在不同时刻的计算结果与现场实测值吻合较好.     

三氧化二铋碳热还原反应的动力学

由于铋元素密度较大,在工业硅碳热还原冶炼过程中容易沉淀,导致冶炼所得工业硅中杂质分布不均,质量下降,因此研究铋在碳热还原反应中的动力学行为,为工业硅冶炼中铋含量的控制提供理论指导具有重要意义。通过热重分析方法研究了不同碳质还原剂对铋氧化物（三氧化二铋）碳热还原的影响。结果表明,石油焦相较于石墨活性更高,石油焦作还原剂具有更好的还原性能。对不同温度下三氧化二铋还原熔炼产物进行了物相分析,其还原反应产物物相转变顺序为：Bi2O3→Bi2O2.5→Bi。通过热重分析法研究了不同升温速率下三氧化二铋碳热还原反应动力学,应用等转化率法、Kissinger法和?atava-?esták法进行动力学分析,得到三氧化二铋碳热还原反应平均表观活化能E0=142.41 kJ/mol,指前因子A0=2.96×109 s-1;反应机理属于相边界反应,对应的动力学方程微分形式为3(1—α)2/3。     

转炉冶炼脱磷过程数学模型

在对复吹转炉脱磷过程的机理分析的基础上,应用冶金热力学、动力学、传输原理和反应工程学理论,建立了转炉冶炼脱磷过程数学模型,确定了模型的有关参数.模型的     

转炉吹炼过程中耗氧比模型

通过对转炉冶炼过程中耗氧比模型的比较及Mn,Si,P氧化机理的分析,应用冶金热力学和动力学建立了耗氧比模型,并根据生产数据的检验结果与模型预测结果的一致性,得出如下结论:供氧强度决定Mn,Si,P的氧化速率;Mn,Si,P在熔池中扩散系数和初始含量的大小将决定各自耗氧比的起始大小;温度通过反应平衡常数影响耗氧比.     

含钒磷铁提钒冶炼试验研究北大核心

本文详细分析了含钒磷铁的物相,根据含钒磷铁中各元素对氧的亲和力不同,采用高温熔体吹氧—选择性氧化的冶炼工艺技术。试验研究了冶炼过程中温度、耗氧量等因素对钒、磷、铁等元素氧化率的影响。试验结果表明:吹氧冶炼温度控制在1350~1400℃、耗氧量为140~160 L/kg时分离效果最为理想,钒的氧化率可以达到95%以上,铁的氧化率控制在45%以下。     

含钒磷铁提钒冶炼试验研究

本文详细分析了含钒磷铁的物相,根据含钒磷铁中各元素对氧的亲和力不同,采用高温熔体吹氧—选择性氧化的冶炼工艺技术。试验研究了冶炼过程中温度、耗氧量等因素对钒、磷、铁等元素氧化率的影响。试验结果表明:吹氧冶炼温度控制在1350~1400℃、耗氧量为140~160 L/kg时分离效果最为理想,钒的氧化率可以达到95%以上,铁的氧化率控制在45%以下。     

高浓度有色金属冶炼烟气脱硫方法研究

在对高浓度有色金属冶炼过程中,烟气是重要的污染元素,为了达到环境保护和有用元素的循环利用要求,相关专家学者对高浓度有色金属冶炼过程中的烟气脱硫进行了研究。传统的脱硫方法使用的是臭氧氧化控制技术,只能脱去烟气中的硫元素,但是产生的二氧化硫和氧化氮无法消除,产生二次污染。为此,提出一种氨法烟气脱硫法,在对高浓度有色金属冶炼烟气脱硫过程中,结合臭氧氧化工艺,通过间歇式密闭均相反应装置对烟气氧化动力进行催化搅拌,采用鼓泡反应对催化氧化烟气进行脱硫,及确定操作参数。仿真实验表明,提出的氨法高浓度有色金属冶炼能够实现有效脱硫,达到环保和金属元素循环使用的双重要求。     

电弧炉冶炼过程强化用氧特点分析

通过电弧炉冶炼过程的分析,提出利用氧气助熔方式降低冶炼过程能耗。利用基本的高温冶金物理化学反应,结合实际冶炼过程,定量计算元素氧化烧损对熔池放热的影响程度。研究发现,在45#钢的电炉冶炼过程中,吨钢吹入10.1 m3氧气能够获得84.308 k W·h的能量补偿。     

金属Cu还原MoO42-的动力学研究

本文对铜还原钼酸盐动力学进行了初步研究.通过还原反应的动力学模型,绘制出其氧化-还原反应机理示意图.同时为了进一步明确其反应机理及动力学过程,采用初始速率法研究还原反应的级数,计算还原反应的活化能,并研究了温度对速率系数的影响.     

铜闪速熔炼过程操作参数预测模型及应用

基于某厂实际铜闪速熔炼工艺和控制过程,对神经网络模型在铜闪速熔炼过程在线控制进行了研究。在分析影响溶剂率、熔炼氧单耗、反应塔总风量操作参数因素的基础上,提出一种基于BP神经网络的操作参数的预测方法,分别建立了输入向量只包含主要元素和考虑杂质元素的BP神经网络模型。网络的训练和测试结果表明,两种神经网络的输出值与实际值的最大相对误差均小于1.0%,输出值与实际样本值吻合得较好,模型输入参数中包括杂质元素时具有更高的计算精度。     

非平衡态热力学分析

为了研究非平衡态热力学理论在具体的冶金过程中的应用,本文用该理论模拟计算了转炉的炼钢过程,并建立了该过程的数学模型。得到了转炉冶炼过程的脱碳速度表达式、钢液中硅锰含量变化表达式、氧含量变化表达式以及温度变化表达式。用C语言对整个冶炼过程进行模拟,结果表明非平衡态热力学模型能够描述整个冶炼过程主要元素的成分变化和熔池温度变化,对转炉炼钢生产实际的过程控制提供了新的理论和方法。     

Performance of a Modified Skapski Model for the Surface Tension of Liquid Metallic Elements at Their Melting-Point Temperatures

From the standpoint of materials process science, the performances of two models for melting-point surface tensions were evaluated by comparing experimental values for 60 liquid metallic elements with those calculated from these models, using a relative standard deviation as a yardstick: One is the Skapski model and the other is a modified Skapski model presented by the authors. The modified Skapski model includes a dimensionless parameter ξ _E ^1/2 characterizing the atomic states of liquid metallic elements. The inclusion of this common parameter to all liquid metallic elements usually makes a noticeable improvement over the Skapski model. With the exception of a dozen or so metallic elements, the calculated values for a large number of liquid metals on the basis of the modified Skapski model are close to experimental values, variations being in the order of ±2 to ±10 pct around the mean. In particular, the modified Skapski model performs very well for most transition and rare earth metals, with few exceptions. Calculated values for these metals fall, or almost fall, within the range of uncertainties associated with experimental measurements of these metals. Finally, it was shown that the values of the numerical factor of the respective liquid metallic elements in the modified Skapski model vary periodically with the atomic number.     

Performance of a Modified Schytil Model for the Surface Tension of Liquid Metallic Elements at Their Melting Point Temperatures

From the standpoint of materials process science, the performances of two models for the melting point surface tension were evaluated by comparing experimental values for 66 liquid metallic elements with those calculated from these models using a relative standard deviation as a yardstick: One is the Schytil model, and the other is a modified Schytil model now presented by the authors. The performance of the Schytil model for a large number of liquid metallic elements, in respect of the accuracy of calculations, is not satisfactory. In contrast, the modified Schytil model incorporating a common parameter denoted by x_T^1/2 \xi_{\rm T}^{1/2} makes a noticeable improvement over the Schytil model. With the exception of some 12 metallic elements, the modified Schytil model performs well for many metallic elements, although the predicted values of x_T^1/2 \xi_{\rm T}^{1/2} were used for calculating the surface tension of 32 (pure metals) of 66 liquid metallic elements; the calculated values fall, or almost fall, within the range of uncertainties associated with experimental measurements. Finally, it was shown that the values of the respective numeric factor for liquid metallic elements, which appear in the modified Schytil model, vary periodically with atomic number.     

An adaptive neuro-fuzzy inference system-based modelling to predict mechanical properties of hot-rolled TRIP steel

A model based on adaptive neural network formalism coupled with fuzzy inference system has been developed to predict mechanical properties of hot-rolled TRIP steel. The developed model incorporates a wide range of data containing chemical compositions, thermo-mechanical processing parameters and mechanical properties of hot-rolled TRIP steel. A compact set of process variables has been selected as the model inputs for predicting tensile strength, yield strength, elongation and retained austenite under a given operating condition. The model predictions show that carbon, silicon and manganese content have a significant effect on the retained austenite which increases with the increased amount of these elements. The microalloying elements such as niobium and molybdenum have a little effect on the volume fraction of retained austenite. The present model provides a predictive platform for possible application of these artificial intelligence-based tools for automation, real-time process control and operator guidance in plant operation.     

Dynamic Spar Elements and Discrete Element Methods in Two Dimensions for the Modeling of Soil-Inclusion Problems

Discrete element methods (DEMs) provide new numerical means to study the behavior of soil-inclusion systems. In some cases, however, the classic DEM fails to model specific aspects of the inclusions. That is why a model based on spar elements is introduced, designed specifically for inclusions. In this model, the movement of the inclusion is considered as a dynamic process and is computed step by step in the same way as in the DEM. The model can be coupled with a DEM code, thus enabling one to simulate the interaction between an inclusion and a disk assembly. Contact laws at the contacts between disks and spar elements describe the interface constitutive behavior. Finally, the results obtained by simulating a geosynthetic anchorage in two different ways are reported. In the first case the inclusion is represented by disks, while in the last case it is represented by spar elements. The comparison shows that spar elements are much more versatile and can simplify the calibration of the discrete models used to simulate soil-inclusion systems.     

单机架冷轧机全干扰耦合模型的建立与分析

在高品质薄板冷轧带钢生产中,板形、板厚和张力之间的耦合关系是近年来的重要研究课题。运用轧制理论系统地分析了单机架冷轧机轧制过程中所有控制量和干扰量对板形、板厚和张力的影响,并由此建立了单机架冷轧机全干扰耦合模型,而后采用Matlab/Simulink工具对该模型的耦合特性及干扰响应特性进行了仿真分析。该模型能够定量计算各因素对控制目标量的影响,较好地反映出单机架冷轧机的控制特性。在对模型分析的基础上指出了单机架冷轧机完全解耦设计和抗干扰设计的必要性。     

Stream Surface Strip Element Method and Simulation of Three-Dimensional Deformation of Continuous Hot Rolled Strip

A new method, the stream surface strip element method, for simulating the three-dimensional deformation of plate and strip rolling process was proposed. The rolling deformation zone was divided into a number of stream surface (curved surface) strip elements along metal flow traces, and the stream surface strip elements were mapped into the corresponding plane strip elements for analysis and computation. The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal were respectively constructed to be a quartic curve and a quadratic curve, of which the lateral distributions were expressed as the third-power spline function, and the altitudinal distributions were fitted in the quadratic curve. From the flow theory of plastic mechanics, the mathematical models of the three-dimensional deformations and stresses of the deformation zone were constructed. Compared with the streamline strip element method proposed hy the first author of this paper, the stream surface strip element method takes into account the uneven distributions of stresses and deformations along altitudinal direction, and realizes the precise three-dimensional analysis and computation. The simulation example of continuous hot rolled strip indicates that the method and the model accord with facts and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process.     

Mathematical modeling of the argon-oxygen decarburization refining process of stainless steel: Part II. Application of the model to industrial practice

The mathematical model proposed and presented in Part I of the present work has been used to deal with and analyze the austenitic stainless steel making (including ultralow-carbon steel) and has been tested on data of 32 heats obtained in producing 18Cr9Ni-grade steel in an 18-t argon-oxygen decarburization (AOD) vessel. The results indicated that the carbon concentrations and bath temperatures at the endpoints of blowing periods, calculated by the model, are in excellent agreement with the determined data, and the Cr content after the predeoxidization, obtained from the model predictions, also agrees very well with the observed value. The Gibbs free energies of the oxidation reactions of elements can be used to characterize fully the competitive oxidation among the elements during the refining process and to determine reasonably the corresponding distribution ratios of oxygen. The critical carbon concentration of decarburization (after which the decarburization changes to become controlled by the mass transfer of carbon in molten steel) for the AOD refining process of austenitic stainless steel in an 18-t AOD vessel is in the range of 0.25 to 0.40 mass pct. The model can provide some very useful information and a reliable basis for optimization of the technology of the AOD refining process of stainless steel and control of the process in real time and online.