Barrons AP Environmental Science

Samples are taken from the area to determine the quality and quantity of the
minerals in a location and, if the site meets the criteria above, the site is prepared
for extraction (e.g., access roads, utilities, preparation of waste dumps and waste
ponds, etc.).

2. EXTRACTION

Three main methods of extraction exist:

I.  Surface mining

II. Underground mining

III.    In  situ    (in place)  leaching

I.  SURFACE MINING: Surface mining, including   strip   mining, open-pit    mining,

and mountaintop removal mining, is  a   broad   category    of  mining  in  which

the soil    and rock    overlying   the mineral deposit (the    overburden) are

removed.    Surface mining  is  used    where   deposits    of  commercially    useful

minerals    are found   near    the surface and where   the overburden  is  relatively

thin    or  the area    is  unsuitable  for tunneling.  Surface mines   are typically

enlarged    until   either  the mineral deposit is  exhausted   or  the cost    of

removing    larger  volumes of  overburden  makes   further mining

impractical.

There   are four    main    forms   of  surface mining:

1. STRIP MINING is the most commonly used method to mine coal or tar
   sand. It is the practice of mining a seam of mineral by first removing a
   long strip of overburden.
   Area stripping is used on fairly flat terrain to extract deposits over a
   large area. As each long strip is excavated, the overburden is placed in
   the excavation produced by the previous strip.
   Contour stripping involves removing the overburden above the
   mineral seam, near the outcrop in hilly terrain, where the mineral
   outcrop usually follows the contour of the land. This method
   commonly leaves behind terraces in mountainsides.


2. OPEN-PIT MINING refers to a method of extracting rocks or minerals
   from the earth by removing them from an open pit.


3. MOUNTAINTOP REMOVAL MINING is used where coal seam outcrops all