Monolithic Lining for Steel-Pouring Ladles

The increasing amount of steel being treated outside the furnace and the increase in the quantity of molten metal being transported by rail in ladles are making it necessary to tighten standards on the durability and service life of the ladle linings. Plans developed for a new department at the Chelyabinsk Metallurgical Combine to line steel-pouring ladles will make it possible to replace the traditional brick lining by cast linings composed of refractory concrete. This change will make the lining considerably more durable, decrease accidents, and sharply reduce the amount of manul labor required in the lining operation. This article describes the process and equipment used to make the new monolithic linings.__________Translated from Metallurg, No. 3, pp. 39–40, March, 2005.     

Dynamic monitoring of slag oxidation and thickness in the ladle-furnace unit

Methods are proposed for ongoing monitoring of the slag oxidation and the depth of the electrical arcs in slag at the converter shop of OAO EVRAZ NTMK. Such monitoring is expected to increase the rate of metal heating, reduce the ferroalloy and power consumption, and increase the lining life in casting ladles.     

Modernization of the Equipment of the Continuous Strip Caster of a Hot-Rolling Mill

To reduce metal consumption and improve the quality of the finished rolled product, ISPAT-Karmet has begun to modernize the equipment of its 1700 hot-strip mill. The modernization will include the following: automation of control of the thermal and temperature regimes for heating slabs in the continuous furnaces used with the mill; installation of newly designed manifolds in the hydraulic scale-removal system, with Lechler nozzles, to increase pressure in the hydraulic system from 120 to 160 atm; installation of heat-absorbing shields, designed by the Novokramatorsk Machine Plant (NKMZ), on the intermediate roller table between the roughing and finishing trains of the mill; use of rolls made of high-chromium cast iron in the finishing stands; modernization of the automatic process control system, with replacement of the existing equipment by Siemens programmable controllers and the installation of new Klek width gages after the final finishing stand; installation of a new NKMZ-made combination system for laminar cooling of the strip on the runout table of the mill; installation of a closed hydraulic system to control the configuration of the strip (the system was designed by the company Mess) on finishing stands 6–12; installation of a system to automatically regulate the speed regime during coiling. The results obtained from the initial modernization of the equipment on the 1700 hot-strip mill have already eliminated rolled-in scale on the strip surface, reduced metal consumption by 8.7 kg/ton through a reduction in the width tolerance for the strip, increased the service life of the work rolls in the finishing stands from 175,000 to 350,000 tons, expanded the product mix, reduced electric power consumption by 7.0 kWh, and reduced the consumption of comparison fuel by 0.8 kg/ton.     

Simulation of thermal history of work rolls of finishing stand in hot strip mill: a numerical approach

Abstract

The work rolls in the finishing stands of any hot strip mill (HSM) experiences thermal shock owing to changes in temperature from initial boundary conditions. The thermal expansion owing to the change of temperature is a major contributing factor to the final shape or the profile of the strip generated at different stands of finishing stands of the HSM. A mathematical model has been developed for the prediction of temperature profile for the surface and the inner depth of the roll in the finishing stand of a HSM. The numerical result from the model calculates the temperature profile in each stand of six finishing stands of the HSM and the corresponding thermal expansion at different stands. The temperature profile and the thermal expansion of the work rolls for a complete rolling schedule have been found from this model. The measurement of the thermal expansion has been found to match closely with the calculated one.     

回转窑烘窑新工艺的应用

回转窑作为高温煅烧物料的主要设备,被广泛应用在铝用阳极石油焦的煅烧过程中.为确保回转窑内衬修理后的质量,在内衬修理后的启动升温过程中,根据耐火材料的理、化特性及浇筑后水分溢出的情况,制定了严格的烘窑制度,烘窑制度制定的合理与否,直接影响到回转窑内衬的使用寿命.本文从升温曲线测温点的选择及不同内衬修理位置升温曲线的细分等方面,就烘窑制度的优化进行探讨.     

Role of silicon in the formation of the corrosion resistance of austenitic materials for cryogenic engineering

The effect of silicon on the operational efficiency and corrosion resistance of low-temperature equipment made of 12Kh18N12T chromium-nickel steel has been studied. The specific features of the cryogenic equipment consist in high-temperature heating procedures between operation periods. Equipment for gas liquefaction and cleaning aimed at the restoration of the operational efficiency of filtration and catalysis systems serves as an example. The heating temperature of this equipment can reach 800°C. Experimental steels containing 0.09–1.03 wt % Si are subjected to intercrystalline corrosion tests. Upon heating to 550–600°C, silicon is found to increase the corrosion resistance of the steel, and, upon heating at higher temperatures, silicon plays a negative role. This is caused by the distribution of silicon atoms along grain boundaries, namely, a nonuniform silicon distribution with the formation of high-and low-concentration regions, i.e., the formation of clusters of silicon-phase preprecipitates.     

鞍钢2号酸洗—冷轧联合机组设计方案浅析

鞍钢新轧钢股份有限公司将原１２００ｍｍ和１７００ｍｍ单机架可逆轧机拆除，以新建的５机架冷连轧机与现有的盐酸酸洗机组联合，形成鞍钢２号酸洗－冷轧联合机组，其生产能力为１００万ｔ。该机组是我国首次２自己设计和制造的大型冷轧设备。意义深远。本文从设备选型、工艺、电气及控制系统等方面对该机组的设计进行了分析。     

武钢CSP加热炉内衬的优化设计

武钢CSP加热炉炉衬较薄,使用全纤维模块砌筑,其隔热性能好,但使用寿命较短。在保证炉衬厚度不增加、隔热效果不降低的前提下,通过传热计算对炉衬材料进行了优化设计。耐火层选用浇注料延长使用寿命,分析了隔热层分别采用纤维毡、纳米隔热板、超级憎水隔热板等不同隔热材料对外表温度与散热量的影响,确定了合理的材料组成,达到了既能延长使用寿命,又能降低成本的目的。     

一种双机架六辊 UCM 平整兼二次冷轧机组

针对传统双机架平整兼二次冷轧机的系列问题,开发了一套双机架六辊UCM平整兼二次冷轧机组。该机组相对传统机型增加中间辊窜辊、中间辊弯辊等板形调节手段,更好地改善板形;该机型采用1＃机架乳化液直喷辊缝润滑、1＃机架配置双辊系,大幅度降低轧制力、提高轧制稳定性;该机型开发乳化液阻隔及防结露装置、辊缝吸尘装置及支承辊擦拭器等装置,降低板面乳化液残留、消除金属粉尘,提高产品质量,减少环境污染。     

Technology for chemical preheating of automotive-grade and tube steels in the ladle

The converter shop at the Severstal’ Metallurgical Combine has developed and introduced a unit for the chemical preheating of steel in pouring ladles. When the filled ladle arrives at the steel-finishing unit, the steel is blown with argon in accordance with existing procedures. Measurements of temperature are then used to evaluate the need for chemical heating of the steel. The mass of aluminum to be used for this purpose and the total consumption of oxygen are calculated based on the steel’s temperature and aluminum content. The chemical heating technology can be used in the production of ordinary steels, automobile sheet 08Yu, and tube steel 22GYu. When IF-type automobile sheet is being made, the amount of oxygen used for chemical preheating should be limited to 100 m³. __________ Translated from Metallurg, No. 2, pp. 45–47, February, 2007.     

提高加盖钢包自开率的研究与实践

首钢京唐300t钢包加盖后自开率明显下降，分析了加盖钢包自开率下降的机理，确定了主要原因是包衬温度升高后造成的液态渣回流。通过对引流砂的流动性、密度和渗钢性研究，设计了一种适用于加盖钢包的引流砂成分配比，并通过控制Al2O3和MgO含量，保证铬矿砂纯度。改进了钢包热修工艺，设计了针对加盖钢包的投砂操作和防钢渣回流措施。研究结果经推广使用后，钢包月不自开炉数由8～9炉降低至2炉以内，综合自开率达99.9%，双精炼工艺自开率达100%。     

基于ANSYS有限元法的型钢轧机机架分析

利用ANSYS有限元法对南京钢铁公司中型厂850轧机机架的变形及分布进行分析,结果表明,最大应力出现在压下螺母孔圆角处,并用实测值对模拟计算结果进行修正,得到轧机的力学性能理论结果,为现场工艺的制定和设备的维护和使用提供了理论依据。     

Study of the sintering of bronze granules by the method of high temperature metallography

Summary A procedure has been developed for the direct observation of the sintering of uncompacted metal powders in the IMASH-1 high-temperature installation. The mechanism by which metallic contacts between tinned bronze granules are initiated and propagated during heating has been established. It was found that, with increasing rate of heating, the temperature of metal contact formation and granule surface melting decreases, as a result of which it is possible to produce filters with a relatively high tin content of the surface layers of granules.     

Use of a heat-insulating mixture to reduce heat loss from pig iron during its transport and reduce the size of the salamander in hot-metal-car ladles

Commercial trials have been conducted on a new heat-insulating mixture designed to lengthen the period between repairs to refractories, reduce heat losses during the transport of pig iron, and alleviate salamander formation in the ladles used for transport. The use of mixture TIS-1 has in fact decreased the amount of heat lost during the transport operation, raised the temperature at which the pig iron is delivered to the customer, and lengthened the time the pig can remain in the ladle before solidifying. However, the mixture has not alleviated the salamander problem, due to the 11–12-h ladle turnaround that currently exists.     

Durability of Brick Lined Steel Ladles from a Mechanical Point of View

The refractory lining in steel ladles is exposed to chemical and mechanical loads during the heats. Mechanical loads develop from the thermal expansion of the refractories which is confined either by the steel construction or by regions of different temperature within the refractory material. The aim of this work was the investigation of factors influencing the mechanical durability of refractory steel ladle linings and the clarification of failure mechanisms. Especially irreversible strains at the hot face of the working lining caused by compressive stresses induce an opening of joints at the hot face. The irreversible strains reduce the compressive stresses in circumferential direction and increase the probability of tensile failure. A further effect of the irreversible strains is a reduced stability of the working lining. Of special interest in this context is a possible controlled expansion of bricks to counterbalance the irreversible compressive strains.     

Chromium-bearing starting mixture for filling the steel-discharge channel of casting ladles

A chromium-bearing starting mixture has been developed, put into production on an industrial scale, and introduced in steel-casting ladles at converter and electrosmelting shops.     

热连轧精轧宽度自动控制

为了提高热连轧带钢成材率和宽度精度，国外一些钢厂开发了精轧宽度自动控制系统，在精轧机架间设置了测宽仪，利用机架间张力动态调整带钢宽度，实际应用表明，带钢宽度偏差有明显减少。     

A study on the mechanism of reaction between refractory materials and aluminium deoxidised molten steel

The conditions of formation of inclusions in steel during ladle refining in MgO-C lined ladles have been investigated in laboratory experiments at 1873 K in MgO-C crucibles with 50 g iron. From both the experimental results as well those of a thermodynamic study conducted in parallel, the following conclusions can be made about the reaction mechanism between the MgO-C refractory and aluminium deoxidised molten steel: At steelmaking temperature an internal oxidation-reduction occurs in the MgO-C refractory. The formation of a thin oxide layer at the interface is due to the reaction between magnesium vapour and aluminium dissolved into the molten steel and the CO(g) generated by the reaction between MgO and C in the crucible walls. The oxide inclusions formed in the steel have been shown mainly to consist of MgO, Al₂O₃ or mixture of them. Some of the finest inclusions are considered to be formed as secondary inclusions during cooling and solidification of the steel and they are connected only with the diffusion of magnesium from the crucible to the molten steel. The thermodynamic calculations indicate that during vacuum refining, as the pressure decreases, the chemical compatibility of carbon-bonded magnesia for ladle lining decreases.     

包钢炼钢厂3#LF炉改进渣系的研究

为了进一步降低生产成本、优化工艺操作,转炉车间从减少造渣剂用量、优化精炼渣系和抓操作工操作技能入手,通过深入细致的探索攻关、多次的试验、逐步规范操作等途径,成功地实现了3#LF炉精炼渣系的调整.不仅使工艺流程更加顺畅,而且吨钢生产成本降低12.33元.     

自动化技术在宝钢钢管轧机改造中的应用

在宝钢分公司140mm无缝钢管厂的改造中,使用了一些先进的自动化控制技术.文章以张减机控制系统为例,介绍了自动化控制技术在钢管厂轧机控制系统改造中的应用,包括切头控制(CEC)、平均壁厚控制(WTCA)等.开发了可由任意个机架参与控制的CEC技术取代原来固定使用12个机架参与的CEC控制,扩大了CEC覆盖的产品范围;开发了4种机架组合参与控制的8条WTCA张力控制曲线,取代原来由固定6个机架参与的一条控制曲线,增加了参与WTCA控制的机架数量,提高了WTCA的控制效果;利用检测到的钢管壁厚和当前使用的控制参数,采用控制算法在线修正张减机的轧制参数,不断地优化控制参数.