Syllabus Coverage: NFC1.1, NFC1.2
Uranium is the 48th most common element in the Earth’s crust. Although not particularly uncommon, economically viable deposits are rather scarce. Some key facts about uranium abundance:
- Average concentration in the Earth’s crust: ~2-4 ppm (parts per million)
- Granite (which forms ~60% of the Earth’s crust): ~4 ppm
- Minable surface deposits: ~1,000 ppm (equivalent to 0.1 wt%)
- Richest known deposits (deep underground): up to 20 wt%
- Seawater: ~3 ppb (parts per billion), totalling approximately 4 billion tonnes of U in the world’s oceans
Historical Note: Japan developed a method to recover uranium from seawater in 1986, extracting 5.3 kg at a cost of $1,940/kgU (compared to a spot price of $44/kgU at the time). This was clearly uneconomical and was quickly abandoned.
The four main methods of uranium mining, and their approximate shares of world production, are:
| Method | Share of World Production | Typical Application |
|---|---|---|
| Underground mining | ~41% | Deposits too deep for open pit; requires high-grade ore |
| In situ leaching (ISL) | ~26% | Sandstone deposits below the water table |
| Open pit mining | ~24% | Shallow deposits |
| By-product recovery | ~9% | Uranium recovered during mining of other minerals |