Once an ore has been taken from the earth, it still must undergo
refining in order to be able to be used. Ore taken straight from the
ground usually consists of only a small percentage of the desired
material. This must be seperated out, through sintering, or some other
method. This purifies the ore. Some ore deposits may require several
refining steps in order to draw out enough impurities to be able to work 
with the material successfully. The higher quality the ore, after
refining, the higher quality material that can be produced from it.
Usage: use refining at <material type> in <work bench>