Man's physical universe

xanabras

UNIT IX

SECTION 2

METALLURGICAL PROCESSES HAVE MADE POSSIBLE

THIS AGE OF METALS

Introduction.

The use of coal to replace charcoal in

the smelting of iron and the

invention of the steam engine inaugurated the industrial revolution.

Our modern industrial civilization is still based on iron, and every

year has witnessed new methods of producing harder, tougher, and

stronger iron alloys (steels). Up until recent times the corrosion of

iron nearly kept pace with its extraction from ores, but modern

research has developed many corrosion-resistant alloys and other

methods of combating corrosion.

New metals and alloys have entered industry in competition with

steel. Chief among these new metals is aluminum, the most widely

distributed and most abundant metal, though practically unknown

until the twentieth century because of the highly specialized means

required for its extraction. Suitably alloyed and treated, aluminum

One of the trends in mod-

has properties rivaling those of mild steel.

ern metallurgy is toward lighter alloys.

Every year sees fresh progress in the field of metallurgy, and there

is hardly any branch of the history of civilization more fascinating

than that which traces the development of man from the Stone Age

to the Metal Age of today.

Progress in Metallurgy Has Depended on the Widespread Use of

Metals.

Metallurgy is the science and art of preparing metals for use from

their ores. The metallurgical processes depend upon the nature of the

ore and the metal to be separated. The metallurgy of the heavy

metals differs in general from that of lighter ones.

The metallurgical operations (often called smelting) of the heavy

metals fall into four groups: (1) The ore is separated from useless

foreign material by various concentration methods. This is done by

hand selection, sifting, washing with a stream of water, and froth

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