| mining. |
stone drivages; primary development (SME Mining Engineering Handbook, 3rd Ed., 2011:
"Two types of development exist in mining: primary and secondary. The main difference between these two types is the life expectancy of the development.
Primary implies long life and includes such items as shafts, declines, and other mine accesses; main tunnels, haulages, crosscuts, ore- and waste passes, crusher chambers, and other large chambers. Thus primary development is the development of the more permanent features of a mine. These do not have to be developed early in a mine life, but they need to have a relatively long life span.
Secondary development is more temporary in nature and tends to be associated with the needs of a particular production unit or units. In many cases this type of development is consumed as production proceeds. Thus a typical lifetime for this type of development is 1 or 2 years and is often less than this." masizonenko) |
