Resourcebull.Try this link, it provides a good explanation of...

Resourcebull.

Try this link, it provides a good explanation of the JORC code in the coal mining industry.

http://www.jorc.org/pdf/jorc_code_coal_Hunter_AusIMM.pdf

The coal loss is subject to loss and dilution during coal recovery from pit, and also during processing. The processing or washing will be subject to the coal's ash content. Given these factors I would doubt that you would lose more than 50% of the coal.

I am a senior mining engineer in the coal industry, and given my experience, 200 to 300m would be quite a deep opencut even with high quality coking coal.

Hope this helps you.