The Fruits of Civilization (23-4-3) Metallurgy


Europe was never naturally rich with precious metals, though more ordinary ores were relatively abundant.

Silver mining was well-established in the Middle Ages. It hit a boom in the early 16th century with the discovery of the mercury amalgamation process which concentrated silver ore. The rather obvious toxicity of mercury went largely unappreciated.

Copper, iron, lead, and zinc were found in many areas of Europe, and have been mined since prehistoric times. Tin was more localized, found most abundantly near Cornwall. Tin had been an item of commerce before the Romans conquered Britain.

Responding to demand, mining techniques improved in the 16th–17th centuries: deeper shafts, better ventilation, and pumping machinery. Most mining innovations came from Germany. The technology spread as German miners went abroad. In the 1560s, the British government granted monopolies to brass and copper companies which then hired in German engineers.

In medieval times, iron was wrought from various types of bloomeries. The iron was heated using charcoal until it became a pasty bloom, whereupon it was alternately hammered and heated to drive the impurities out. Output was small, owing to a slow, laborious, inefficient, and costly process in terms of ore and fuel.

The blast furnace was invented in China in the 1st century, and incrementally reinvented in Europe, beginning in the late 14th century, with the height of furnaces progressively increasing. The same fuel – charcoal – was used, but the process was different.

Fuel, ore, and a flux to remove impurities – typically limestone – go in from the top. A blast of air from a bellows increases the heat. Chemical reactions take place as the material flows down the furnace. Metal and slag emerge at the bottom while flue gases escape from the top. Thus, in the 16th century, the blast furnace evolved.

Numerous innovations occurred to facilitate the blast furnace, including water-powered bellows, tilt hammers, and stamping mills for crushing ore. Other related inventions followed, including rolling and slitting mills, and wire-drawing machines. While more efficient, blast furnaces were also more capital-intensive, though much of that went to maintaining inventories of ore and charcoal.

The Low Countries, particularly the southeast region around Liège and Wallonia, were involved with metallurgy during the Middle Ages. At the beginning of the 16th century, this region led Europe in iron-making innovation. Germany, northern Italy, and northern Spain were also major centers, with Germany accounting for around half the production by volume.

Metallurgy technology spread over the next 100 years. England especially embraced iron. By 1625 it had 100 furnaces producing 23,000 tonnes per year.

The iron industry was a voracious consumer of fuel. In the 17th century, the high price of charcoal hindered expansion. In a larger context, energy resources became a limitation to industrial growth throughout Europe.