I am trying to make sense of the mining process of minerals or metals.
- I found two measures related to waste: the stripping ratio (which is usually larger than 3:1 for copper, i.e. 3 tonnes of waste for one tonne of copper ore) and the ore grade (which is <5% for copper, i.e. out of a tonne of copper, you can extract only 50kg copper). Is my interpretation correct?
- How do they stack up in the mining process? Using a 1% ore grade and 3:1 stripping ratio, does that mean that to get 1 tonne of copper, we need to move 400 tonnes of earth, as we need 100 copper ore that comes along with 300 tonnes of waste?
- Does the same logic apply to rare earth mining as well? I found the following numbers for the Bayan Obo mining district in China (see ):
- Neodymium content: 18.5%
- REO(rare earth oxide) grade: 4.1%
- Recovery rate: 50%
- Tonne mined/tonne REO: 49
So according to my understanding, to get one tonne of neodymium, we need 49/(18.5%*4.1%*50%) = 12920 tonnes. Is that correct? That would be a lot of mining for a tonne of neodymium.
Ultimately, I am interested in the amount of earth that has to be moved/mined to get one tonne of copper/other metals (which of course depend of course on the mine and the ore grade).
Thanks a lot :-). I am trying to make sense of the numbers to get a better understanding of the footprint of certain technologies (e.g. given that there are 2 tonnes of neodymium in a modern wind generator, we need to remove 26,000 tonnes of earth to get the neodymium for this (if my numbers are correct).
Best regards, ProGeologist.
 Rare Earth mining: https://ui.adsabs.harvard.edu/abs/2013JOM....65j1327T/abstract - tables on page 1329 and 1331