Views: 0 Author: Site Editor Publish Time: 2023-02-10 Origin: Site
In the Old World, the first metals to be smelted were tin and lead.The earliest known cast lead beads were found at the site of (Turkey) and date to around 6500 BC,but the metal may have been known earlier.Since this discovery occurred thousands of years before the invention of writing, there are no written records of how it was made.However, tin and lead can be smelted by placing the ores in a wood fire,which makes it possible that the discovery may have happened by accident.Lead is a common metal,but its discovery had relatively little impact in the ancient world.It is too soft to be used in structural elements or weapons, although its high density relative to other metals makes it ideal for sling projectiles.However, due to its ease of casting and shaping,it was widely used by workers in the classical world of ancient Greece and Rome to transport and store water.They also used it as a mortar in stone buildings.Tin is far less common than lead, just slightly harder,and has less of an effect on its own.
Copper and bronze
After tin and lead, the next metal to be smelted appears to be copper.How this discovery came about is debated.The campfires were about 200 °C cooler than needed, so it has been suggested that the first smelting of copper may have occurred in pottery kilns.(It is believed that the development of copper smelting in the Andes independently of the Old World probably occurred in the same way.The earliest known evidence of copper smelting dates back to 5500-5000 BC at Pločnik and Belovode in Serbia.Mace heads found in Turkey dating back to 5000 BC,once thought to be the oldest evidence,now appear to have been hammered from natural copper.Combining copper with tin and/or arsenic in the correct proportions produces bronze,an alloy that is much harder than copper. The first copper/arsenic bronzes date from Asia Minor around 4200 BC.Inca bronze alloys are also of this type.Arsenic is often an impurity in copper ores,so the discovery may have been made by accident.Ultimately,arsenic-containing minerals were intentionally added during the smelting process.Harder and more durable copper-tin bronzes also appeared in Asia Minor around 3500 BC.How the blacksmiths learned to produce copper/tin bronzes is not known.The first such bronzes were probably a lucky accident from tin-contaminated copper ore.However, by 2000 BC, tin was being intentionally mined to produce bronze remarkable because tin is a semi-rare metal, and even cassiterite-rich ores contain only 5% tin. However,early people knew about tin, and they learned how to use it to make bronze by 2000 BC.The discovery of copper and bronze manufacturing had a major impact on the history of the Old World.Metal is hard enough to create weapons that are heavier, stronger,and more resistant to impact damage than their wood, bone, or stone equivalents.For thousands of years,bronze was the material of choice for weapons such as swords,daggers,battle axes, spears and arrow points, as well as protective gear such as shields,helmets,greaves (metal shin guards) and other body armor.Bronze also replaced stone,wood, and organic materials in tools and household utensils such as chisels,saws, adzes,nails, blade scissors, knives, sewing needles and pins, jugs, cooking utensils and cauldrons, mirrors, and horse tack.Tin and copper also helped create trade networks that spanned large swaths of Europe and Asia and had a major impact on the distribution of wealth among individuals and nations.
Early iron smelting
The earliest evidence of ironmaking is a mixture of small iron fragments and modest amounts of carbon found in the original Hittite formations of Kaman,dating to 2200-2000 BC.Souckova(2001) shows that ironware was made in central Anatolia around 1800 BC,in very limited quantities,during the Neo-Hittite Empire (1400-1200 BC), although not by civilians , but commonly used by elites.
Archaeologists have found signs of iron working in ancient Egypt, between the Third Intermediate Period and the 23rd Dynasty (c. 1100-750 BC).Remarkably, however, they found no evidence of iron ore smelting in any (pre-modern) period. In addition, an early instance of carbon steel was produced in northwestern Tanzania around 2000 years ago (around the first century AD), based on a complex preheating principle.These discoveries have significant implications for the history of metallurgy.Most early processes in Europe and Africa involved smelting iron ore in smelters,where temperatures were kept low enough that the iron did not melt.This creates spongy slabs of iron, called billets,which must then be strengthened with hammers to produce wrought iron.The earliest evidence to date of iron smelting is found at Tell Hammeh in Jordan, dating to 930 BC (14th century AD).
Later iron smelting
From the Middle Ages, an indirect process began to replace the direct reduction of the bloomers.It uses a blast furnace to create pig iron, which must then undergo further processing to create malleable iron bars.The second stage of crafting involves refining in ornate forges.Blast furnaces were introduced from China in the 13th century during the High Middle Ages and were used as early as 200 BC during the Qin Dynasty.Puddles were also introduced during the Industrial Revolution.Both processes are now obsolete, and wrought iron is rarely made these days.Instead, low carbon steel is produced by Bessemer converters or other means, including smelting reduction processes such as the Corex process.