Mining and Smelting

In today's lesson, we take a look at some of the vocabulary surrounding the mining and smelting industries. Let’s look first at some key vocabulary. Prospecting: Prospecting is often the very first stage in the search for mineral deposits. Drill sampling: A small hole is pierced into the ground and a sample of rock is brought to the surface. Ore: a mineral that has a high concentration of a certain element, typically a metal. By the way, an ore is always a mineral, but a mineral is not always an ore. Surface mining: This is a broad category of mining in which soil and rock lying on top of the mineral deposit are removed. Sub-surface mining: consists of digging tunnels or shafts into the earth to reach buried ore deposits. Ore milling: a process to crush rock and separate ore from waste material. Smelting: A process that uses heat or chemicals to separate the metal from the ore. Mining is a very important industry and key player in the economies of certain countries. For example, mining is a very important industry in my adoptive home of Peru. The principal metals mined here are copper, gold, zinc, and silver. Mining exports are one of the most important drivers of the economy. The first step in the mining process is prospecting. This is when geologists and other professionals search for mineral deposits hidden underground. Once they discover a location likely to contain minerals, they take the exploration process one step further and conduct drill sampling, where they extract ore samples from underground. If the concentration of a valuable metal within the ore sample is high enough to make mining profitable, they look for investors to develop the mine.  Exploration is a risky business though: Less than one per cent of exploration projects typically progress to establishing a mine. Mines come in many different shapes and sizes, and I am no expert, but for the sake of this podcast lesson, let’s break them up into two main categories: surface mining and sub-surface mining. With surface mining, the miners dig and remove the soil on rock that sits on top of the mineral deposits. This can leave massive holes in the ground. With sub-surface mines, on the other hand, the mineral is reached through a system of tunnels and shafts. Probably for most of you, this is what you imagine when you think about mining. Men –– and it is almost always men –– in hard hats going down deep into the earth to access the minerals. When mines are operated without proper safety standards, this can still be a very dangerous job. Now, once the ore is removed from the mine, it needs to be processed to separate the minerals from the waste material. Processing the minerals is first done at an ore mill where the ore is broken and crushed into smaller pieces and washed. This can involve large amounts of water. Ore mills generate large amounts of waste, called tailings. For example, 99 tons of waste are generated per ton of copper, with even higher ratios in gold mining – because only 5.3 g of gold is extracted per ton of ore, a ton of gold produces 200,000 tons of tailings. Once the milling is finished, the final step is smelting, where the valuable metal is extracted from its ore by a process involving heating and melting. This process uses a lot of electricity, and smelters have been known to produce water and air pollution, especially at older smelters.