BY KAVIT PASSARY, Passary Minerals Limited
Refractory materials for lining metallurgical vessels have always played an important part in crude steel production. Although their function used to be almost exclusively one of protecting the steel casings of the vessels, they must today be regarded as an intrinsic component of metallurgical process.
Modern refractory technology is not based on the properties of the materials alone any more. It has rather grown into a technology including heat engineering, monitoring techniques, furnace design, lining installation and furnace operation. The refractory technology developed with advancements in technological innovations of iron and steel making processes.
While the definition correctly identifies the fundamental characteristic of refractories, which is their ability to provide containment of substances at high temperatures, refractories comprise of a broad class of materials having that characteristic to varying degrees, under varying periods of time and conditions of use. Refractory compositions are wide ranging, fabricated in various shapes and forms, and have been adapted in a broad range of applications. The common factor is that they will be subjected to temperatures above 1000°F (538°C) when in service.
Refractory products fall under two categories:
a. Brick or fire shaped refractories and
b. Specialties or monolithic refractories
Refractory linings are made from these bricks or from specialties such as plastics, castables, gunning mixes or ramming mixes, or from a combination of both.
Refractory materials have a crucial impact on the cost and quality of steel products. The diversification of steel products and their purity requirements in recent years have increased the demand for high quality refractory. Steelmaking requires high temperatures of the order of 1600 degree centigrade. In addition, steelmaking involves chemically reactive high temper phases like molten steel, slag and hot gases, which necessitates the use of refractories. Since the cost of refractory adds into the cost of the product, high quality refractory at a cheaper cost is the main requirement.
Refractories have the potential to make or spoil. Every high temperature operation needs an assurance system of energy saving. The right quality, quantity and engineering of refractories can save energy and prevent loss of money.
|Refractories need repairs: Good quality refractories need lesser times of repair, thus resulting in less downtime. The cost saved by reducing downtime is higher than the cost of refractories.
Refractories contain heat: Its failure can cause accidents that can result in loss of lives. Therefore, for safe and employee friendly operations, refractories must be rightly chosen and applied.
Refractories erode: Refractories erode over time. The eroded particles mingle in the system and add impurities in the product. Good quality refractories erode lesser, resulting in lesser impurities and give more value for money.
Refractories evolve: New technologies appear from time to time, which contribute to easier, safer and speedier applications. The variety of refractory materials available today makes it possible to combine different kinds of refractories and customize them. This ability to be customized is a unique feature and makes refractories more interesting and attractive to the customers.
In comparison to other industries, the refractory industry is small. It is yet to receive due recognition because of its negligible size in comparison to the key user industries like steel, cement, aluminum etc. However, it is a highly specialized industry and its contribution to the Indian economy cannot be overlooked.
Source: Steel 360 Magazine July’16 Issue