Why is it too expensive to extract copper from contaminated land?

Answer 1

It takes a lot energy to extract some metals from their ores.

It can be done by smelting or by electrolysis, both of which require lots of energy.

In smelting this comes in the form of carbon (coal or similar), while in electrolysis it comes in the form of electricity.

Another reason for the cost is because you need to look for, and then dig up the original ore which is expensive, and finally transport the ore or the copper to its final destination.

However copper is not THE most expensive metal to extract. The more reactive the metal, the more expensive it is to extract.

Metals like lead, do not really react much and are require less energy to extract. Copper is nearer to this end - not too reactive. In fact gold does not react at all and is found in its pure state.

At the other end are metals like sodium, potassium and aluminum which would really much rather stay in their ore. These take a lot of energy to extract and can only be done by electrolysis.

Answer 2

The cost of the process is proportional to how much material (rock, dirt, whatever) you have to process. The more material to be processed, the bigger the equipment, or the longer you have to run it, and the more power and other other materials you need.

You might hope to pay for the process by selling the copper you get, since copper is a valuable metal. But if the amount of copper you get is only a small fraction of the amount of material you have to process, you might not get enough copper to sell to cover your expenses. That's probably what you mean by it being "expensive."

Consider the extreme case: what if there is no copper at all? In that case, you spend a ton of money grinding up a lot of rock, reacting it with acids, running electric current through it, etc

-- and end up with a lot of slag (waste). That would certainly be a foolish proposition!

Or the other extreme: what if the material was 100% copper already? In that case, all you need to do is gather it together into one spot, melt it into convenient ingots, and put up a "Copper For Sale" sign. That would be very profitable!

Reality lies in between, usually. Good copper ore is about 1% copper by weight, and the value of the copper is enough to compensate for the cost of extracting it. But for less than perhaps 0.2% copper, you will spend more getting the copper out than you can sell the copper for.

Answer 3

It's too expensive to extract copper from land using traditional method because the quarrying and heating of the metal would result in an energy expenditure that would make mining copper counterproductive.

Answer 4

Copper is often found in thin veins within the surrounding rock. This means that the ore bearing rock must be mined as a whole, the ore is then processed, and the waste deposited, while the copper is processed into pure copper.

Answer 5

because it is mined from caves.