Editorial Feature

An Introduction to Metallurgy: Mining Fundamentals

Metallurgy involves extracting valuable metals from their ores and refining the extracted metals to a purer, more commercially viable form. This article will examine the fundamentals of metallurgy.

metallurgy mining fundamentals

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Metals occur in either their free or combined state. For example, non-reactive metals, such as gold, platinum, and silver, are usually found in their free state, while more chemically reactive metals, such as iron, copper, or aluminum, are found in their combined state. Minerals from which these metals are extracted are called ores.

Metallurgy typically refers to commercial methods, which are different from laboratory methods. The science of metallurgy also includes the principles of making alloys by combining metals and the atomic, physical, and chemical properties of metals.

Classification of Ores

Ores are classified based on the type of compound that the metal forms, as below:

  • Native Ores: Those that contain metals in their free state
  • Sulphurised and Arsenical Ores: These contain metals such as sulfides or arsenides
  • Oxide Ores – These ores contain the oxide form of metals
  • Halide Ores – These ores consist of metallic halides

Metallurgical Processes

There are three general steps in metallurgical processes:

  1. Mining and removing the ore from the ground
  2. Separating and concentrating the metal or compound
  3. Reduction of the ore to produce the final metallic product

The chief metallurgical processes are described below.

Mining and Extracting Ore

Mining is one of the oldest economic activities in human history. While the principles of mining and extracting ore for concentration and metal extraction have remained mainly unchanged for millennia, technological progress means that today's methods vastly differ from those used in ancient times.

Metal-containing ores are extracted from surface or deep underground mines. They are then transported to locations where the concentration and purification processes occur. This complex process involves drills, ore trucks, and conveyor belts.

Concentration of Ore

The concentration of ore involves the removal of impurities and other physical processes, such as magnetic separation, hydraulic washing, and froth floatation.

Conversion of Ore Concentrate to Oxide

The concentrated ore is then converted into its oxide form through roasting, calcination, and reduction.

Metal Refining

The metal is refined via liquidation, electrolysis, and distillation.

Extractive Metallurgy

Metallic compounds are complex mixtures and cannot usually be extracted via simple processes. Before extractive metallurgy can commence, the compound must typically be converted into a more easily treatable form. Once this conversion has been performed, the metallic constituents of the compound can be separated from the other constituent materials.

In this process, metal sulfides are converted into oxides, chlorides, or sulfides; oxides are converted to chlorides or sulfides; carbonates are converted to oxides.

This stage of the metal extraction process employs several processes, including hydrometallurgical and pyrometallurgical practices. Pyrometallurgy includes smelting and roasting, whereas methods such as electrowinning (which applies an electric current to the compound solution) and leaching (selective diffusion using an aqueous solution) are used in hydrometallurgy.

Pyrometallurgy

Oxidation and reduction are two of the most common pyrometallurgical processes. In oxidation, metallic oxides are formed due to metals' affinity for oxygen, which are then further treated to separate pure metals from waste products. Reduction involves feeding a metallic oxide into a furnace along with a reducing agent, releasing combined oxygen and leaving a carbonaceous oxide and uncombined metal.

Roasting involves specialized roasters such as rotary kilns and blast, flash, and fluidized-bed roasters. Different types of specialized roasts include chloridizing roasts, volatilizing roasts, oxidizing roasts, and calcination. Roasting can be exothermic or endothermic.

Reduction and matte smelting are the two main types employed in pyrometallurgy. Blast furnaces reduce smelting to produce oxides from the metallic charge and slag. Matte smelting produces matte, a homogenous metallic sulfide, and the slag produced is in its oxide form.

Blast furnaces are universally employed in reduction smelting, differing slightly in construction depending on which type of metal is produced. Matte smelting uses equipment such as reverberatory furnaces and electric furnaces. As well as reduction and matte smelting, flash smelting has emerged in recent years and is becoming widely accepted in commercial metallurgy. Electrolytic smelting is also used.

Hydrometallurgy

Hydrometallurgical processes are employed for low-grade ores, which would make more expensive extraction processes less economically viable. A solution is formed from which the pure metal can be extracted and refined. Leaching usually involves preliminary processes such as controlled roasting to reduce the ore and produce a calcine that can easily dissolve in the leaching solution.

Pressure oxidation is a common treatment for sulfides. This involves preheating a concentrated slurry, which is then pumped into agitator-containing compartments in an autoclave with gaseous oxygen added to it. Oxidation typically takes about two hours.

Different solvents are used depending on the metallic compound being leached. For instance, sodium carbonate or sulfuric acid is used to leach oxides, whereas sulfuric acid or water is used for sulfinates. Precious metals are leached using a cyanide solvent.

Physical Metallurgy

Physical metallurgy involves the production of commercial products from metals, producing metal parts with various desired electrical, physical, chemical, structural, and aesthetic properties. Depending on the desired product, various forming methods are used, such as sheet metal for automotive fenders or powder metallurgy for small parts.

All You Need To Know About Metallurgy | iKen | iKen Edu | iKen App

Video Credit: Iken Edu/YouTube.com

In Summary

Metallurgy is a complex, interdisciplinary field encompassing various processes, from the extraction of ores to the production of refined metals.

Understanding the principles and techniques of metallurgy, such as pyrometallurgy, hydrometallurgy, and physical metallurgy, provides insight into how raw materials are converted into essential components for modern life. From the initial mining of ores to the complex techniques used to refine and shape metals, metallurgy remains a crucial foundation for numerous industries, powering technological advancements and economic growth worldwide.

Continue Reading: How Has Mining Changed Over Time?

References and Further Reading

Encyclopedia Britannica (2024) Metallurgy [online] Available at: https://www.britannica.com/science/metallurgy

Knight, J (2024) Metallurgy through the ages [online] Encyclopedia.com. Available at: https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/metallurgy-through-ages

Jiang, L.Y (2017) Chapter 1 – Metallurgy: Importance, Processes, and Development Status Membrane-Based Separations in Metallurgy pp. 3-18. [online] Available at: https://www.sciencedirect.com/science/article/abs/pii/B9780128034101000013

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Article Revisions

  • Nov 8 2024 - An informative video was added to the article to provide readers with more insight into the topic.
  • Nov 8 2024 - Meta description changed from "Metallurgy may be described as the process of working metal into tools and artifacts. Metals are less commonly found in their pure form;in most of the cases they are found as their ores. Copper and iron were the first used metals by early man." to "Understanding metallurgy involves exploring ore extraction, metal refining, and the principles of alloy creation, which are essential for modern industrial applications."
  • Nov 8 2024 - This article was fully rewritten to ensure the most up-to-date information and a more thorough look at the subject was provided. References and images were consequently changed and updated.
  • Nov 8 2024 - Title was changed from "Metallurgy - Mining Fundamentals" to "An Introduction to Metallurgy: Mining Fundamentals"
Reginald Davey

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Reginald Davey

Reg Davey is a freelance copywriter and editor based in Nottingham in the United Kingdom. Writing for AZoNetwork represents the coming together of various interests and fields he has been interested and involved in over the years, including Microbiology, Biomedical Sciences, and Environmental Science.

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