I. Ferrous Metal Smelting and Rolling Processing

Ferrous metal smelting generally refers to smelting iron ore into pig iron, or smelting pig iron into steel billets. Rolling processing is a type of processing that involves rolling steel billets into steel plates or various section steels, where pressure is applied to the metal to stretch it into a specific shape.

II. Ferrous Metals

Ferrous metals mainly refer to iron and its alloys, such as steel, pig iron, ferroalloys, cast iron, etc.

1、Steel

Steel is a general term for iron-carbon alloys with a carbon content (by mass percentage) ranging from 0.02% to 2.11%. The chemical composition of steel can vary significantly; steel containing only carbon is called carbon steel or plain steel.

2、Pig Iron

Pig iron is an iron-carbon alloy with a carbon content exceeding 2%. Industrial pig iron typically has a carbon content of 2.11% to 4.3% and contains elements such as C, Si, Mn, S, and P. It is a product obtained by smelting iron ore in a blast furnace. Based on the different forms of carbon present in pig iron, it can be further divided into several types, including steelmaking pig iron, foundry pig iron, and ductile iron.

3、Ferroalloys

Ferroalloys (English: Ferroalloys) — in a broad sense, ferroalloys refer to a type of product added to molten iron during steelmaking as deoxidizers, element additives, etc., to endow steel with specific properties or meet specific requirements. They are intermediate alloys composed of iron and one or more elements, mainly used in iron and steel smelting.

In the iron and steel industry, generally, all intermediate alloys used for steelmaking, regardless of whether they contain iron (e.g., calcium-silicon alloys), are also called "ferroalloys". Customarily, certain pure metal additives and oxide additives are also included in this category.

4、Cast Iron

Cast iron is a general term for alloys mainly composed of iron, carbon, and silicon. In these alloys, the carbon content exceeds the amount that can be retained in the austenite solid solution at the eutectic temperature.

Classification of Smelting Methods

1、Pyrometallurgy

Also known as dry metallurgy, this method involves heating ore together with necessary additives in a furnace to a high temperature, melting them into a liquid state, and triggering the required chemical reactions to separate crude metal, which is then refined.

2.Hydrometallurgy

Hydrometallurgy is a metallurgical process that uses aqueous solutions of acids, alkalis, or salts to extract the required metal components from ore through chemical methods, followed by producing metals using various techniques such as aqueous electrolysis.

This method is mainly applied to low-grade, refractory, or fine-powdered ores. Currently, 75% of the world’s zinc and cadmium are produced using the roasting-leaching-aqueous electrolysis method, which has largely replaced the traditional pyrometallurgical zinc smelting process. For other metals that are difficult to separate (e.g., nickel-cobalt, zirconium-hafnium, tantalum-niobium, and rare earth metals), new hydrometallurgical technologies such as solvent extraction or ion exchange are used for separation, achieving significant results.

3、Chemical Reaction (Metallurgy)

It refers to a metallurgical process that uses a specific solvent to extract and separate metals from raw materials through chemical reactions (including oxidation, reduction, neutralization, hydrolysis, complexation, etc.).

Hydrometallurgy plays an important role in industries such as zinc, aluminum, copper, and uranium. All of the world’s aluminum oxide and uranium oxide, most of the zinc, and part of the copper are produced using hydrometallurgical methods.

The advantages of hydrometallurgy include its applicability to very low-grade ores (e.g., gold, uranium) and to scenarios where similar metals (e.g., hafnium and zirconium) are difficult to separate. Compared with pyrometallurgy, it involves a simpler material circulation process, a higher degree of comprehensive recovery of valuable metals from raw materials, is more conducive to environmental protection, and its production process is easier to achieve continuity and automation.