Metallurgy

Article

July 5, 2022

Metallurgy is a complex science dealing with the extraction of iron and other metals from their ores, refining, alloying, casting, plastic shaping, heat treatment, examination of their structure and properties, and the mechanical equipment used.

Iron and metallurgy

Metallurgy in the narrower sense is metallurgy, which deals with the extraction of metals from ores, and can be grouped according to the nature of the technology used: fire metallurgy (pyrometallurgy), hydrometallurgy, electrometallurgy. Grouping according to metals: iron metallurgy (this includes the production of iron and steel), metallurgy (production of all "non-ferrous metals").

Iron metallurgy

The two main areas of iron metallurgy are: pig iron production and steel production.

Pig iron production

The task of iron metallurgy is to extract pig iron from iron ores and then further process it into cast iron and steel. The essence of the fire metallurgy of iron is that oxygen is removed from the iron ore, which is essentially a mixture of oxide iron compounds, by reduction. Reduction is carried out with coal, mostly in the form of coke. In addition to reduction, the task of coke is to ensure the appropriate temperature. Pig iron production takes place in a blast furnace in a special shaft furnace. The ore, coke and limestone are poured into the upper part (throat) of the blast furnace. The impurities removed from the ore must be slag, which is usually achieved by adding limestone. In order to ensure the correct temperature, a significant amount of air is blown into the oven through nozzles designed for this purpose. Pig iron is produced during the process. The reduced and melted iron collects in the basin at the bottom of the smelter, separated from the also melted slag based on specific gravity. Both can be tapped from here.

Steelmaking

Steel is produced from pig iron and/or steel waste (scrap). The purpose of steel production is to remove impurities from the raw material and to ensure the desired chemical composition by adding alloying substances. Steel production processes: converter steel production, electric steel production. Siemens-Martin steel production, which was considered to be dominant for a long time, has now practically been pushed out of production, its place has been taken over by converter and electro processes. These methods can also process pig iron and scrap iron. Several methods of the converter process are known (Bessemer and Thomas processes), but today the most common is the LD process (the abbreviation LD refers to the place where the process was developed: Linz-Donawitz). In this method, a so-called they blow oxygen through an oxygen lance. As a result of this, the contaminants on the surface of the metal bath - and due to the continuous internal flows of the metal bath throughout its mass - oxidize (burn out) and become slag. Alloying agents are added separately to the metal. The electric furnaces can also be started with a pure scrap insert.

Metallurgy

Metallurgy is the collective term for the science and practical technology dealing with the production (metallurgy) of "non-ferrous" ores. Within metallurgy, the metallurgy of light and heavy or non-ferrous metals is separated (the names heavy and non-ferrous metals are used synonymously in practice). The dividing line between light and heavy metals is usually drawn at a density of 4.5 g/cm³. From the point of view of practice, the most important light metals are aluminum, magnesium and titanium. Among the non-ferrous metals, copper, nickel, lead and zinc are the most important. The first metal most likely known to man was gold. The golden nuggets soon f