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The process technology of iron and steel making is undergoing rapid changes throughout the world. Larger capacity blast furnaces and taller coke ovens are the order of the day. Basic oxygen steelmaking processes are replacing the conventional method of steel making in open hearth furnace. Vacuum degassing, continuous casting, slide gate valves etc are also gaining popularity.The service conditions required to be met by refractories in the modern iron and steel making units are very much severe demanding improved quality of materials.In India, some of the existing steel plants are on the threshold of expansion and a few mini steel plants are also being put up. All these units are expected to adopt some of the latest techniques in iron and steel making requiring improved quality of refractories which are not available in our country at present. The quality of refractories that would be required in future are reviewed in this paper with a view to focusing on the possibilities of manufacturing them indigenously.

Currently, the stoves of blast furnaces are operated at a higher temperature for increasing productivity. Consequently, the demand on the quality of checker bricks has increased. In TISCO, the blast furnaces are operated at a hot blast temperature of 900°C. An attempt has been made to evaluate the refractories available from indigenous sources. Various physical and chemical properties of the bricks have been analysed along with their mineralogical constituents. Compressive creep characteristics have also been evaluated.

In Tisco, the stopper rod sleeves used are of moderate heat duty quality. During the teeming of low carbon highly oxidised steels, severe erosion of sleeves, resulting in stopper rod failures, posed a problem. A coating material was developed and tried on the sleeves which gave encouraging results. Coating of sleeves has been adopted as a regular shop practice.

In recent years, sand slinging process is being used for lining ladles in steel plants. The slung mixes are made from naturally occurring sands or mixture of synthetic grains with suitable binders.In our country, ladle bricks constitute a major tonnage of fireclay bricks in the steel plants. An attempt was made to use sand as lining material in steel ladles to reduce the consumption of refractories and also to save time in relining.Work was undertaken to develop sand slinging mixes of proper composition utilizing indigenous sand. The mixes were tried in steel ladles, used for transferring blown metal from bessemer shop and hot metal from mixer to open hearth furnaces.

In the past, there were a few major refractory failures in blast furnaces of TISCO, viz. hearth break-outs, damage to the throat lining, etc. These furnaces were repaired and put back to operation. Premature failures also were experienced in the hot blast stoves, particularly in the checkers. In this communication, a few such occurrences and the details of repair work done, have been discussed.

During the dismantling of coke ovens, large quantity of silica waste was recovered and an investigation was undertaken to find out suitable means to utilize these materials. The use of silica grog for making brick was restricted due to its high grain porosity and inversion of cristobalite at lower temperature which seriously affects the bond strength.Work was undertaken to develop proper composition with suitable binders for making bricks utilizing the silica waste. The bricks were made and tried in the ladles used for transferring blown metal from Bessemer Shop to Open Hearth furnace. Encouraging results were obtained in the initial trials.

Performance of ladle refractories has a considerable influence on the production and productivity of any steel making unit. Poor quality of refractories reduces the ladle life, leading to increase in consumption and cost. Such situations can be avoided by improving the ladle life.Trials were undertaken with bloating type, 37% alumina and 42% alumina bricks and results were studied. Initial trials indicated that about 15 to 20% life could be increased with the use of 42% alumina ladle bricks. Intensive trials done recently also confirmed the increase in life of about 20 per cent. Physico-chemical changes of these bricks during service have also been discussed.

Soluble silicate (sodium silicate) has been used as bond in ceramic and refractories industry for a long time. The versatile nature of this material resulting from alkali silica reaction offered several advantages in many fields of refractory application. Additional advantages with respect to strength and rapid setting can be obtained by incorporating foreign ions, which reacted with colloidal micelles of silica in solution. Studies were undertaken with different additives for finding out the effect on strength and setting characteristics with aluminous and siliceous base materials. The mixtures were fired at various temperatures and their properties were evaluated.

During the last two decades, several developments have taken place in the field of iron production. Necessary design changes were made in the blast furnaces to suit the demands. The furnaces are driven harder for increased productivity by incorporating the sinter in the burden, increasing the hot blast temperature, etc. These improvements in the field of metallurgy naturally demand better refractories and construction methods. This article reviews some of the latest developments in the refractory construction and other improvements incorporated in the blast furnaces of the Tata Iron & Steel Company.

Conventional repairing practices of the worn out portions of the furnace with the bricks require longer time and sometimes a perfect job cannot be done due to inaccessibility of places. These problems of repair are overcome by the ‘Gunniting’ technique. In this article gunniting technique and various types of materials used are discussed and a review of the published work has been made. Application of the technique as practised in various parts of the authors' plant has been described.

During the last one decade considerable developments have taken place both in the design and the operation of Blast Furnaces. To suit these demands corresponding changes and developments have taken place in the field of refractories fjr Blast Furnaces as well. Many new types of refractories have found their way in this field in place of Alumino-silicate refractories.The changes and developments in the qualities of the refractories used in the various zones of Blast Furnaces have been reviewed.

The rate of teeming steel as obtained with various types of nozzles was studied. Heats of approximately 140 tons and 230 tons were considered. Low-fusible or bloating type clays give an uneven rate of pouring, undesirable from the metallurgists' point of view. Magnesite nozzles which do not wear out, give too slow a rate of teeming at the end. Tar-impregnated clay nozzles of medium refractoriness give a more uniform rate of pouring.

Productivity of a Bessemer Shop depends on the availability of the vessels, which in turn largely depends on the life of the bottoms. Properties of the material used in the bottom, procedure of preparing the ramming mass and ramming of the bottom have been described. Study was undertaken in the plant for finding out various factors that affect the life of the bottom. Results of the trials undertaken in the plant have been described.

High alumina monolithic with phosphoric acid as a binder are being used extensively in metallurgical furnaces. Development work was undertaken in the range of 60 to 90% aluminous material with indigenous raw material, e.g. bauxite, kyanite and diaspore. Phosphate bond was developed with certain additives without being detrimental to the physical properties.

Roof Cleaning is one of the means adopted by different steel plants throughout the world for increasing the roof life of open hearth furnaces. With the adoption of basic roof in TISCO, it was observed that the roof was getting over-heated and the tabs holding the bricks were getting cut. This resulted in premature failure of roof requiring frequent hot repairs. It was presumed that the dust accumulation in the roof was acting as insulation altering the thermal gradient and enhancing the liquid migration deeper in the brick. Laboratory investigation confirmed this assumption. In TISCO, roof cleaning has been undertaken regularly to overcome this problem which has resulted in improving the roof life considerably. The practice has been extended to the silica roof also with considerable success.

Silica bricks are used in oven walls, regenerator division walls, roof covers and sole of coke ovens. Specifications followed in different countries are discussed. Data on iron oxide and lime bonded bricks obtained from indigenous sources have been given. Causes of refractory failure of the ovens and maintenance procedure that are followed in Tata Iron and Steel Co have been discussed.

Investigations were made on premature failure of refractories of Blast Furnace Stove. It was found that holes of the checkers were clogged due to dust accumulation. Brick surface became glazed and top few courses of t bricks were completely vitrified and deformed.Samples were collected from different zones of the stove and laboratory investigations were made. The chemical analysis and the fusion point of dust and glazed portion of brick, indicated that high dust content of blast furnace gas and prolonged dome temperature of 1250°C and the chocking of the holes were the factors that caused failure of refractories of the stove. It is suggested that for longer life of refractories the gas should be cleaner. If the temperature of the stove is required to be raised in order to increase the temperature of hot blast, the top few feet of checkers, combustion chamber walls and dome should be relined with high alumina refractories.

Eiffciency and productivity of Blast Furnace depends on the performance of Hot Blast Stoves. Recent trend is to operate the Blast Furnaces with a hot blast temperature of 1000°C and above. Various modifications are necessary in the design and the quality of refractories used in the stoves to obtain the hot blast temperature in that range. Problem is more aggravated when changing the existing stoves to high temperature operation which is designed originally for low temperature operation. Various refractory problems associated with the changing over to high temperature operation of stoves that are faced in Tisco have been discussed.

A new mechanism for striking of colour in copper ruby glass was recently suggested: 2 Cu-O-Si≡ (chilled glass) striking → Cu2O (red colourant) −+≡Si-O-Si≡. It does not need tin, considered essential as per the earlier mechanism. The actual role of tin has therefore been investigated. A copper ruby glass melted without tin became amber indicating the presence of Cuo. For confirmation, its low temperature viscosity has been studied. Viscosity of chilled glass remains unchanged on annealing. This indicates presence of Cuo in chilled glass rather than of Cu+ which, on annealing, would have increased the viscosity several fold due to formation of bigger structural linkages. Hence in absence of tin the reduction of Cu+ to Cuo is almost instantaneous in the melt and the latter makes the glass amber. Cu+ being absent, formation of Cu2O (red colourant) is not possible on striking. But when tin is used, availability of Cu+ is prolonged. It is likely that tin acts as a protector for Cu+ in molten glass. Probably rea...