Finding ways to make our limited supply of mineral resources last depends on our understanding how much we have and how fast we’re using it. then we can begin to work on ways to use these resources at their sustainable yield. let’s look at the example of uranium.

uranium is mined to use as fuel in nuclear power plants. it is found in various concentrations, but generally a high-grade uranium ore has 2% uranium while a low-grade ore has 0.1% uranium. the estimated accessible uranium resources in the world add up to 4,743,000 metric tons. the united states has about 7% of that, which amounts to 332,000 metric tons.

1. given that the current worldwide usage of uranium is roughly 66,500 metric tons per year, how long will the world’s recoverable resources last? (note that 1 metric ton = 1000 kg =1.1 tons)
2. assume us usage is about 25% of the world’s usage. if the us were to rely only on its domestic supplies of uranium, how long would they last, assuming a 100% recovery rate?
3. assume that most us ore bodies contain high-grade uranium ore and that recovery rates of minerals form the ore average 65%. how many metric tons of ore will have to be mined to meet us needs?