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Copper smelting separates copper from rock through various steps. The process involves grinding the ore into a powder, processing it with chemicals and air, melting it in a high-temperature furnace, and refining it to remove impurities. The process produces waste and sulfur dioxide gas, which can be harmful to the environment. Copper smelting originated in western Asia and is found worldwide, except in Antarctica.
Copper smelting is the process of separating copper metal from the rock into which it is naturally incorporated by smelting. This is achieved through a number of different processing steps. The term copper smelting may refer specifically to this smelting step or it may refer somewhat less formally to the entire process as a whole.
In nature, copper, like many other metals, is found embedded in rock. Such a combination of metal and rock is known as ore. In order for copper to be used in a practical way, it must be separated from rock and other metals and refined to an acceptable purity. Each copper smelting operation has its own unique process, yet many share similar basic steps.
A typical process might begin with grinding the ore into a powder. This powder is processed with chemicals and air to separate some of the unwanted material and concentrate the copper. The unwanted material from this step is referred to as tailings. The tailings are typically disposed of in a tailings pond.
The concentrated material of this stage is then dried and fed into a high temperature melting furnace. As the concentrate is heated, different materials within it separate into layers. A layer of copper-containing molten material, known as the opaque layer, sinks to the bottom. The waste solids, called slag, float to the top. Slag gases and sulfur dioxide are removed and discarded or sold while the opaque layer moves on to the next stage.
Matte is then poured into a converter where it reacts with air, lime and silica to separate the copper from the iron slag. The copper resulting from this step is known as blister copper. The blister copper undergoes further firing and purification to remove any residual impurities.
One of the major side effects of the copper smelting process is the production of waste. Copper refining produces three and a half times more waste than the amount of copper produced. This waste is not only in the form of solids that need to be disposed of or recycled, but also sulfur dioxide gas. Sulfur dioxide is a major air pollutant, particularly known as a precursor to the production of acid rain. Some countries require remediation steps in copper smelting and other industrial operations to mitigate the negative environmental impact of the process.
The earliest copper smelting is thought to have originated in western Asia between 4000 and 4300 BC. Many historians believe ancient potters were probably the first to discover this process. Their open-fire ovens would have been able to reach the high temperature needed. Simple campfires wouldn’t burn enough to melt copper.
Most copper reserves are largely concentrated in a few regions, including parts of the United States and Canada, Zambia and the Andes. Modern copper smelting operations, however, are found worldwide on every continent except Antarctica. Although Antarctica is also a source of copper ore deposits, a long-term moratorium on mining in Antarctica was instituted in 1991 to preserve the area.
