Production and Properties of Metals

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Production and Properties of Metals

Mr J E Chuter, Cert Ed 2012 En No 20100292

Introduction

I have decided to produce a project based on the production and properties of metals, as although I have worked as a welder for over 30 years, and a welding teacher for the last 2 years on apart-time basis, I felt I didn’t know enough information on the material that I work on, on a daily basis.

If I can gain knowledge on this subject, not only will it enhance my subject specialism, but will also give me added confidence when teaching, as any questions that arise relating directly to the material itself, such as, “why does it do this?” or “what happens when ? “ I can give a more direct answer so making me appear more professional and encourage students to seek more information.

The following project looks at the way metals are formed, from the raw materials, right through to the end products and finishing treatments, with some technical info in between.

Information has been extracted from various sources, books, both old and modern, the internet and general companies that process steel, that I have come across in my working environment.

Production and Properties of Metals

The term metal production refers to all of the processes involved in the conversion of a raw material, such as a metallic ore, to a final form in which the metal can be used for some commercial or industrial purpose. In some instances, metal production involves relatively few steps since the metal already occurs in an elemental form in nature. Such is the case with gold, silver, platinum, and other so-called noble metals. These metals normally occur in nature uncombined with other elements and can therefore be put to some commercial use with comparatively little additional treatment.

In the majority of cases, however, metals occur in nature as compounds, such as the oxide or the sulphide, and must first be converted to their normal state. They may then be treated in a wide variety of ways in order to make them usable for specific applications.

Metals always occur in their oxidized state in ores, often as the oxide or sulphide of the metal. In order to convert an ore to its elemental state, therefore, it must be reduced. Reduction is a chemical reaction that is the opposite of oxidation. Metals can be reduced in a variety of different ways.

With ores of iron, for example, reduction can be accomplished by reacting oxides of iron with carbon and carbon monoxide. One of the common devices used for this purpose is the blast furnace. The blast furnace is a tall cylindrical vessel into which is fed iron ore (consisting of oxides of iron), coke (nearly pure carbon) and limestone. The temperature in the blast furnace is then raised to more than 1,832°F (1,000°C). At this temperature, carbon reacts with oxygen to form carbon monoxide, which in turn, reacts with oxides of iron to form pure iron metal. The limestone in the original mixture added to the blast furnace reacts with and removes silicon dioxide (sand), an impurity commonly found with iron ore.

Some metallic oxides do not readily yield to chemical reduction reactions like those in the blast furnace process described above. The reduction of aluminium oxide to aluminium metal is an example. Until 1886, no economically satisfactory method for carrying out this process had been discovered. Then a young college chemistry student, Charles Martin Hall, invented an electrical method for reducing aluminium oxide.

Von Zeerleder (1946), The Technology of Aluminium and its Light Alloys, Third Edition, Slough Bucks, High Duty Alloys Ltd

In the first step in this process, aluminium oxide is separated from other oxides (such as oxides of iron) with which it also occurs by the Bayer process. In the Bayer process, the naturally occurring oxide mixture is added to sodium hydroxide,...
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