Expansion Joints for Steel Plants

Introduction

It is impossible to imagine a world without steel. Humans have been making iron and steel for centuries. Steel drove the industrial revolution and remains the backbone of modern industrialised economies.

Steel, in terms of its composition and properties, its strength-to-weight ratio and its ability to be infinitely versatile in new products, distinguishes it from other materials and has been fundamental to its success.

Steel is produced from iron ore or scrap. Iron ore is a mineral aggregate that can be converted into iron. The quality of iron ore is mainly determined by its composition; high iron content and low sulphur and phosphorus content are favourable. Iron ore is found all over the world, but its iron content varies.

A valuable raw material for steel production is scrap, which has been collected and recycled for decades.

In steel production, the following stages are categorized: production of pig iron, production of liquid steel, hot rolling and cold rolling, application of a metallic and/or organic coating.

There are two main processes for producing steel: by means of a blast furnace (Indirect Reduction) in combination with a converter, or by means of an Electric Furnace. In the blast furnace process, iron ore is the main raw material. In an electric furnace, scrap iron is used and occasionally also sponge iron. Sponge is an intermediate product, which is produced from iron ore by means of direct reduction (DRI or directly reduced iron) and that is then further reduced and smelted in an electric furnace.

Before iron ore can be used, oxygen must be removed from it. Known as ‘reducing’, this can be done either in the blast furnace, where hot air is injected into a continuous feed of coke, sinter and lime, or by the direct reduced iron (DRI) process. The result from both is liquid iron, which is then transported to the basic oxygen furnace. The blast furnace process also produces two important by-products: carbon dioxide (CO2), and slag (a mixture of minerals).

MACOGA supplies customized Expansion Joints for Midrex ironmaking process, developed for the production of direct-reduced iron (DRI) from iron ores and primarily natural gas. Midrex is a gas-based shaft furnace process that converts iron oxides, in the form of pellets or lump ore, into direct reduced iron (DRI).