Copper Casting Methods

People have been mining copper and refining it for several thousand years already. In fact, some historians estimate that copper was first used for creating copper castings in or around 9,000 BC. Ever since then, different ethnic groups have been using copper to make weapons, jewelry, and of course, drinking vessels.

Not only is copper a good conductor of heat and electricity, but it can also easily be worked and added to other various metals in order to form alloys such as bronze or brass for example.

During the Bronze Age, it became extremely popular to mix copper with zinc or tin in order to make bronze or brass. Because these alloys are noticeably stronger and harder than copper, countries that were able to develop these alloys inevitably became more powerful than their neighbors. Interestingly enough, copper castings and alloy castings were already popular in the time of the ancient Egyptians. Brass on the other hand first became popular with the early Greeks and it was soon adopted by the Romans as well.

The most common process to reduce the copper ore to pure copper ingots was by using heat; the oldest method was to dig a hole about 12 inches deep, line it with heat resistant rock or clay, put the crushed copper ore in and add a layer of charcoal, which was then set on fire. The addition of air pumped from a bellows kept the heat at the proper temperature.

At the end of the process, you would be left with a large clump of slag, with the refined copper in the center. As civilizations became more adept at refining copper they began to use a special pottery vessel to reduce the copper ore even further in order to obtain copper of a superior grade, and of course this purer form of copper was easier to use for making copper castings.

At a later stage in history, a different method was also employed. This would involve allowing water to run across to the surface of the copper ore, which in turn resulted in a large amount of copper. At that point, iron would be added in order to induce evaporation, at which point the copper would replace the iron. Interestingly enough, Christopher Columbus had the hulls of his ships coated with copper in order to resist corrosion and other marine relegated damage.

Ores which contain sulfur and copper are often smelted using a method known as "flash smelting". This method which was originally developed in Finland and it’s considered to be more environmentally safe than most other methods. During this process, the copper ore is dried out and ground down into a powder. The powder is then sprayed over a special reactor in order to reduce it to a molten state. Because the sulfur is reduced to a solid form, it poses less of a risk as far as toxicity is concerned.

Nowadays, copper is for the most part refined by using state-of-the-art electric furnaces. Just as in the past, there is still a huge demand for copper in the world. Not only is it used for making copper castings, but it’s also widely used in the manufacturing of electrical wiring and many other electrical components. A large amount of the world’s copper is still being used to make bronze and brass, and of course, alloy castings remain incredibly popular even today.

Mark Smith is Manager of AA Alloy Foundry, a Copper Castings Company located in the East Rand, South Africa. To get more information on Copper Castings, click on Copper Castings This article, Copper Casting Methods is available for free reprint.