Monitoring the wear of the refractory lining in the blast-furnace hearth

Abstract

A blast furnace is a metallurgical system of shaft type. Its internal working space is bounded by a refrac tory lining, which is intended to protect the furnace's metal structures from high temperatures and to main tain the initial geometric configuration of the working space for a long time. Numerous factors break down the lining: impacts (when the charge is introduced in the furnace); abrasion (as the batch descends in the shaft); wear by the hot metal and slag; and the penetra tion of soot, zinc, and alkalis into the lining seams. The destructive effect is greatest in the lower part of the furnace: the lining of the well and the hearth. There fore, appropriate measures are taken in the design of the refractory lining and the cooling systems in the well and the hearth, so as to minimize the need for major repairs and ensure reliable furnace operation for 15-20 years.Considerable losses of production occur when large capacity blast furnaces are shut down for lining repair, which may take 2-3 months. The factors responsible for wear and measures for its limitation were considered in [1]. The selection of the cooling system and the refractories and the furnace design are of primary importance here. The hot metal fluxes associated with the hearth design and the quality of the coke employed also have some influence on hearth and hence furnace life. The influence of the produc tivity on furnace life was discussed in [1].At present, Russian and non Russian researchers are interested in the analysis of hearth operation and prediction of its wear, so as to prevent penetration of the hot metal through the lining, which would be cat astrophic. The creation of adequate systems for such analysis and prediction calls for complex mathemati cal software, information regarding the latest achieve ments in blast furnace technology, thermal calcula tions, and computer simulation.At present, the lining thickness may be monitored by measuring the flow rate and temperature difference of the water entering and leaving the cooled furnace section and by means of thermosensors in the lower furnace lining. Other methods are based on ultra sound, radioactive isotopes, elastic shock waves, mea surements of the resistance of electrofurnaces, and so on [2-13].The most promising approach is measurement of the lining temperature and corresponding calculation of the remaining lining thickness on the basis of math ematical models.Existing diagnostic methods based on direct and indirect measurements involve solving nonsteady heat conduction problems and the analysis of huge quantities of data-for example, in formulating a set of possible characteristic states of metallurgical sys tems or their components. The agreement between the models and the actual blast furnace processes depends on the stability of the thermal and geometric charac teristics on which the mathematical models of the refractory lining are based. Monitoring the Wear of the Refractory

Thermophysics – Research Base of Energy- And Resource-Saving Metallurgical Technologies

“…Имет УрО РАН совместно с АО «ЕВРАЗ КГОК» и ОАО «ЕВРАЗ НТМК» выполнены работы по повышению качества агломерата и снижению расхода кокса в доменной плавке [60], а совместно с ОАО «Уралмеханобр» предложена технология переработки титаномагнетитовых руд Тебинбулакского месторождения (Республика Узбекистан) по схеме «доменная печь -конвертер» [61]. Успешно на пяти доменных печах Китая работает разработанная в институте система мониторинга состояния огнеупорной футеровки горна доменной печи [62], которую планируется внедрить и на одной из доменных печей ОАО «ММК».…”

Blast Furnace Hearth Lining: Post Mortem Analysis

“…The non-milled samples were conducted to Scanning Electronic Microscopy (SEM) with X-ray Spectrometry (EDS) 6,7,8,9,10,11 .…”

“…The determination of wear mechanism is fundamental to better understand what happens into the refractory lining during the hot metal production, and it is the basis to decide the better option to protect this refractory layer to improve the furnace campaign. In this way it is possible reduce both the total cost of production and the refractory consumption of this important industrial activity 5,6,7 .…”

“…Both the liquid penetration and the hot gaseous infiltration are allowed through the open porosity this refractory material 5,6,7 . The #2 blast furnace hearth lining of Companhia Siderurgica Nacional (CSN) are composed graphite refractory blocks.…”

Fundamental Investigations as the Basis of Creation of New Materials and Technologies in Metallurgy. Part 1

“…В ИМЕТ УрО РАН разработано аппаратурное оформление и программное обеспечение постоянного контроля разгара огнеупорной футеровки в любой точке горна доменной печи [77], что позволяет увеличить кампанию печи до 20 и более лет, не допуская аварийных ситуаций -прорывов жидкого чугуна. Внедрена разработка на ряде доменных печей Китая по заказу китайской стороны [78].…”