Chemistry Reference
In-Depth Information
Ancient Metallurgy
The extraction of the common metals from their ores in antiquity was based
mainly on relatively simple equipment and processes. Lumps of copper or
iron ore, for example, that may have formed part of a ring of stones around
an ancient domestic fire and become embedded in its embers, could have
been reduced to metal. It is quite reasonable to conjecture, therefore, that
some prehistoric campfire became, quite accidentally, the first metallurgical
furnace. All that is needed to convert a campfire into a smelting furnace is
a small depression in the ground to receive the molten metal. A furnace of
this type is illustrated in Figure 42 (Gowland 1912; Killick 2001).
The study of slags from copper-smelting sites in Wadi Arabah in south-
ern Israel provides an interesting insight into the technology of ancient
copper smelting used there at the time. Some slags, as old as 4000 years, and
others from later times, have remained undisturbed since the time when they
were first made. The ores used for smelting at Wady Arabah were locally
mined malachite, azurite, and/or chalcocite. After mining and ore dressing,
the minerals were apparently crushed into fine granules and mixed with ores
composed mainly of iron oxide or manganese oxide (a reducing agent) as
well as with dolomite or limestone (a flux) and charcoal or wood (the fuel).
FIGURE 42
Ancient smelting furnace.
A simulated ancient smelting furnace used
to replicate ancient metallurgical processes;
(a)
plan;
(b)
cross section.
