 Copper is a valuable metal and has been extensively mined for thousands of years. Some of the uses of copper metal include piping, heat sinks in computers to stop them from overheating, cabling, ship building and as roof coverings. Pure copper metal is rarely found. Usually the copper is found in an ore. Ores contain copper metal but also other minerals. If the ore contains lots of copper metal it is a high grade ore. If it contains low amounts of copper metal it is a low grade ore. There is more low grade ore than high grade ore. But low grade ores can contain less than 1% of copper metal. Unfortunately, due to the extensive mining of copper ore, what you think is happening to the amount of copper metal that's available for making the previously mentioned products. Pause, think and continue when ready. The answer is the amount of copper metal being produced from ores is decreasing. We need ways of extracting copper from any type of ore, whether it's low grade or not. There are two extraction methods that are being used and that we will continue to use in the future. These include wire leaching and phyto mining. Wire leaching is a method of extracting copper metal using bacteria. Some bacteria can live off the energy provided by breaking weak copper sulfur bonds found in ores and replacing them with stronger bonds. When the bacteria break the bond between the copper metal and the ore, what do you think happens? Pause, think and continue. The correct answer is that when the copper sulfur bond is broken, it releases copper metal. The key advantage to this process of producing copper is that it's very energy efficient. Traditionally, copper can be extracted from their ores using electrolysis or by heating them. This requires huge amounts of energy and also releases greenhouse gases like carbon dioxide. The main disadvantage of this method of producing copper is that it's very slow. The other method is phyto mining. Some plants have the ability to extract the copper by growing them on soils that contain a low grade ore. The plants take up the copper and store it inside. Once plants do this, the copper is locked up in the plant. Here's a challenge. How might we unlock the metal from the plants once they are harvested? Pause, think and continue when ready. If you burn the plant, you are left with ashes. Burning adds oxygen to the plant, so all of the carbon and hydrogen are converted to carbon dioxide gas and water vapor, leaving the metallic minerals as solid oxides in the ash, which is where you'll find the copper. Did you get it right? The advantage of this process is that any land that is contaminated with low grade copper can have plants grown on them to extract the copper compounds from the ash. The key disadvantage of this process is that copper produced still isn't pure. This means it needs electrolysis to purify it, and that's not an energy efficient process.