text: The average grade of copper ores in the 21st century is below 0.6% copper, with a proportion of economic ore minerals being less than 2% of the total volume of the ore rock. Thus, all mining operations, the ore must usually be beneficiated (concentrated). The concentrate is typically sold to distant smelters, although some large mines have smelters located nearby. Such colocation of mines and smelters was more typical in the 19th and early 20th centuries, when smaller smelters could be economic. The subsequent processing techniques depend on the nature of the ore.
  In the usual case when it is primarily sulfide copper minerals (such as chalcopyrite, FeCuS), the ore is treated by comminution, where the rock is crushed to produce small particles (<100 μm) consisting of individual mineral phases. These particles are then ready to be separated to remove gangue (silicate rocks residues) using froth flotation.