This is a hard question to have an exact number on because it would have to be decided how do we know a death was caused by a coal mine? Are we referring to dramatic death caused by collapse or explosion? Are we referring to those who die of "black lung" disease or other ailments? And how do we know that all the deaths are being reported and recorded?
As you can see, it is not easy to get a true number, but you can get a pretty good estimate.
Not all nations have data that they make available, so the true number is going to be higher, but take a look at this statistics from the US and China:
US: 2000-2010 = 365
China: 2000-2010= 52,785
As you can see, China is a lot more dangerous place to be a miner! Still, you have to ask yourself:
1. What type of deaths are we including?
2. How is the data collected?
3. What can we guess about countries that don't report this data?
Add in the rest of the world and these numbers are likely to be a lot higher.