Development of Metallurgy

When were the various metals discovered?

The various metals we know today we discovered over a long time span, though these discoveries also accelerated greatly with the development of Chemistry.

Metals Known to Antiquity

	Antiquity		Before 1700		18^th Cent.
Metal	Discovery	Metal	Discovery	Metal	Discovery
Gold	c. 6000BC	Arsenic	1200AD	Cobalt	1735
Copper	c. 4200BC	Zinc	1400AD	Nickel	1751
Silver	c. 4000BC	Platinum	1500AD	Manganese	1781
Lead	c. 3500BC	Antimony	1560AD	Tellurium	1782
Tin	c. 1750BC	Bismuth	1595AD	Tungsten	1783
Iron(smelted)	c. 1500BC			Uranium	1789
Mercury	c. 750BC			Zirconium	1789
				Yttrium	1794
				Beryllium	1797
				Chromium	1797

In the Nineteenth Century

Date	Metal	Date	Metal	Date	Metal
1801	Niobium	1817	Cadmium	1878-85	Holmium
1802	Tantalum	1817	Selenium	1878-85	Thulium
1803	Iridium	1823	Silicon	1878-85	Scandium
1803	Palladium	1827	Aluminum	1878-85	Samarium
1803	Rhodium	1828	Thorium	1878-85	Gadalinium
1807	Potassium	1830	Vanadium	1878-85	Praeseodynium
1808	Boron	1843	Lanthanum	1878-85	Neodynium
1808	Barium	1844	Ruthenium	1878-85	Dysprosium
1808	Calcium	1860	Cesium	1886	Germanium
1808	Magnesium	1860	Rubidium	1898	Polonium
1808	Strontium	1861	Thallium	1898	Radium
1814	Cerium	1863	Indium	1899	Actinium
1817	Lithium	1875	Gallium

In the Twentieth Century

Date	Metal	Date	Metal	Date	Metal
1901	Europium	1945	Promethium	1940-61	Einsteinium
1907	Lutetium	1940-61	Neptunium	1940-61	Fermium
1917	Protactinium	1940-61	Plutonium	1940-61	Mendelevium
1923	Hafnium	1940-61	Curium	1940-61	Nobelium
1924	Rhenium	1940-61	Americum	1940-61	Lawrencium
1937	Technetium	1940-61	Berkelium
1939	Francium	1940-61	Californium

Stages of Development

1. Native Metals

These include gold, silver, copper and iron. The first three are found in rocks and as placer deposits (i.e., in stream gravels). Native iron only occurs in meteorites as a nickel-iron alloy.

Were hammered into the desired shape.

B. First Ores Used

Ores are naturally occurring chemical compounds. They are mostly oxides and suphides, though other more complex molecules also occur (e.g., silicates, carbonates, sulphates).

First ore used was malachite Cu₂CO₃(OH)_2. It can be easily ground into a green power and was originally sought for cosmetics (i.e., eye liner). If thrown into a fire it reduces to a globule of copper.

The presence of carbon in charcoal results in a reducing chemical environment and expels CO₂ or SO₂ leaving the metal behind. Of course, the ancients didn’t know that.

C. Hammering native metals made them denser while heating them made them pliable. The alternation of heating and hammering allowed native metals to be shaped into whatever shape needed (e.g., jewelry, wires, bowls, weapons).

D. Gold and Placer Recovery

Stream water, having gold particles in its sediments, was passed over wool. The gold particles clung to the wool while the remainder was taken away by stream currents. This may be the origin of the Golden Fleece in ancient Greek mythology. The center of gold mining was Egypt, where there were more than 100 gold mines in the Sahara.

E. Silver mining centered in Anatolia during the Hittite Empire. Lead was also

Found with silver either as an alloy or as an adjacent layer beneath it.

F. Cupellation

Galena PbS contains a fraction of silver in the form of an alloy. Galena was

Placed in a baked ceramic pot or crucible. It was melted in the crucible.

This occurred in a reducing chemical environment (the ancients didn’t know

that). A blast of air blown over the molten galena suddenly causes a sudden

oxidizing environment. The sulphide becomes SO2 gas, the lead becomes

PbO dust and blows away. The silver being harder to oxidize remains

Attached to the crucible.

G. Copper was taken in large quantities from Cyprus, which is what its name means. Through use of native copper but mostly from refined ore, copper was hammered into tools and weapons, replacing stone tools.

8. Ancient Mines. Mining evolved by first clearing dirt from rocks where a vein of ore was seen. The miners dug deeper into the earth (40-60 feet down) by digging shafts up to 150 feet diameter. A second shaft was added parallel to the first to provide ventilation and ore was hoisted to the surface by a bucket and rope or by the use of a windlass. Fires were set by the rock face and, once hot, dosed with cold water to induce cracking. The fragments were hoisted aloft.
9. Bronze. Copper was too soft for most uses. But the smelting of ores was not always fastidious. Different ores were mixed together and smelted together. If there was cassiterite (SnS) mixed in with the malachite, bronze resulted. Bronze is an alloy of tin and copper. This was much harder than than copper and shortly replaced copper in tools and weapons. We call the time the Bronze Age. Ultimately, people recognize cassiterite for what it was, a ore of tin, and consciously mixed proportions of tin ore and copper ore to manufacture bronze.
10. Casting. Bronze, copper, gold and silver had low enough melting points to be rendered molten by the furnaces of the ancients. Once liquid it could be pored into molds and be cast. This could make more complicated and detailed features (i.e., filigree, repoussé, and cloisonné). This brought about lots of aesthetic objects.

K. Iron and the Greco-Roman Iron Age

Iron ores were known to the ancients (pyrite FeS and hematite Fe₂O₃). But it took a temperature of 1535^oC to melt iron. The furnaces needed to reach that temperature were not be be made until the Middle Ages. But the ancients had wrought iron. Iron ore under several bouts of hammering causes its impurities and anions to be driven off. The repeated heating and hammering rested in iron which was very strong but which could not be made very sharp. The Chalybes, a subject tribe to the Hittites in 1400 B.C., found away of heating iron ore in contact with charcoal, then hammering it, and repeating the process several times.This drove the carbon into the iron. This is the product known as steel (i.e., .15 to 1.5% carbon in iron). Steel can be wrought to a very sharp edge. This kind of iron replaced bronze tools and weapons in the time of the Greeks and then the Romans.

L. Mercury was discovered around 750 BC. This brought about a new metallurgical process, distillation. Cinnabar (HgS) was smelted in a furnace and mercury vapors rose concentrating at the top of the furnace where it formed, of all things, drops of metal. Mercury was a liquid metal and called quicksilver after its color and physical state. It was discovered that when gold is place in contact with mercury, the gold forms and alloy with the mercury, called an amalgam. This alloy, when subject to a blast, resulted in HgO dust while the gold was left behind in a very pure state. This method of gold refinement received widespread use after this. The result of this method was the contamination of the surrounding environment by mercury.

Repercussions of Metallurgy

1. The readily available native metals and ores were soon consumed. Material had to be drawn from further and further away. This resulted in the development of trade in the ancient world. When the tin in spain was consumed, more was brought in from Cornwall in England.
2. The people who experimented with mixing and melting metals require a specialized knowledge and specialized equipment. Agriculture freed individuals or even tribes so that they could specialize in metallurgy (mining, smelting, hammering and smithing). They discovered ores, found ways of recover them from the earth and developed furnaces, even blast furnaces, to ply their trade. The Chalybes and Cassiterites were such tribes. These artisans were prized by the various empires of the ancient world.
3. The development of furnaces and forges required fuel. The one most common used was charcoal made from trees. The more metallurgy, the more need for fuel, and the more deforestation occurred.
4. Roman operations, while similar to earlier activities, was on a much larger scale. Some mines had as many as 2000 shafts going down as deep as 350 feet. By so doing, ground water leaked into these mines. Pumps were needed to draw the water out so that the mine would not be flooded. Bellows pumps were developed for this purpose. Furnaces were enlarged an supplied with bellows for creating the blast. In addition, pumps were used to rectify the ventilation problems that arouse in these deep mines. Gases were emitted from the rocks and carbon dioxide was given off by the miners. This was part of the ventilation problem. At first, slave labor was used to work Rome’s mines. But eventually there were enough people derive income from mining, that it became a respectable industry operated by individual entrepreneurs. You needed to know something about mine construction to avoid cave-ins and about lever and wheels to hoist the ore out of the mines. Thus mining became a skilled and specialized industry.
5. In medieval times the Stuckofen developed which could raise temperatures high enough to cast iron. This removed impurities better than before but caused more sulfur and phosphorus to be kept in the iron. Farm tools made of stell still made on a small scale.
6. The use of charcoal resulted in whole regions becoming uneconomical because of the need to get wood from further and further away. Centers of iron production shifted to new areas of Europe. More and more national governments needed iron for weaponry. It price rose.
7. Coal was adapted for furnace use in England in the 18^th century. It was also found that coal was useful in making larger quantities of good quality steel.
8. Sir Henry Bessemer develops a method for the rapid, inexpensive way to produce high quality steel in 1855. Buildings now can get taller, ships can be made of steel, etc. the industrial revolution accelerates.
9. Hall Process, an electrochemical means of producing commercial quantities of aluminum (1886).
10. High temperature alloy manufacturing develops (1950’s) produces material for the construction of advanced jet and rocket engines.
11. Silicon chip developed as its manufacture is able to make smaller and smaller chips (1960’s)
12. Finally, the expansion of natural resource exploitation by the discovery of more and newer resources throughout the world increases metal productivity.
13. The environmental costs involved in mineral exploitation

1. Creation of barren regions where extraction occurred.

2. Further development of barren areas where the overburden and spoils piles accumulated.

3. Liberation of soot, sulfur dioxide and carbon dioxide in the regions around smelters and foundaries.

4. Alteration of groundwater flow patterns as ground water seeped into porosity formed by underground mining and open pit mining.

5. Deforestation in the past as wood was cut for charcoal to power furnaces.

6. Erosion of surrounding areas with deforestation.

7. Contamination of soil and water by concentration of toxic metals in spoil piles.

8. Contamination of water by mercury from gold refining.

9. Negative impact on public health by contact with dust and exposure to more refined toxic metals.

Questions About Current Use of Metals

1.) What commodities do we need to import in large quantities? From what unreliable countries do we import them?

2.) What trends in employment and salary have there been in productivity of each of these commodities? What are the implications of these trends toward reliance on other countries? (Table 1)

3.) What economic trends are seen in the productivity figures? (Table2)

4.) If we continue to rely on other countries for commodities, which states will be affected? (Table 3 & Maps)