The diverse deposit factors means that the mining technical conditions are various, so there is no single mining method that can be applied universally. Two different mining methods have formed through the long-term mining practice: open pit mining and underground mining.

Open pit mining refers to ground mining preparation and stripping by excavating open trenches. Underground mining is to reach and explore the ore body through a number of underground shafts and tunnels.

Selection of mining method:

Despite the vast difference among deposits, there are some objective laws for selecting the mining method.

a. If the deposit occurrence and extension are shallow, open pit mining should be adopted.

b. If the deposit occurs deeply, underground mining should be adopted.

c. If the upper deposit occurrence is shallow and the extension is deep, open pit mining and underground mining should be adopted for the upper deposit and lower deposit respectively. In this situation, there should be a transitional period in the midterm of production.

d. If the upper deposit occurrence is deep and the extension is shallow, both methods can be adopted for the deposit.

The first two situations can be easily identified. In the third and fourth cases, comprehensive techno-economic analysis should be conducted to determine the boundary between open pit mining and underground mining and to decide the appropriate method.