Acid mine drainage where the ore is a sulfide mineral or is associated with pyrite. In these cases the predominant metal ion may not be iron but rather zinc, copper, or nickel. The most commonly mined ore of copper, chalcopyrite, is itself a copper-iron-sulfide and occurs with a range of other sulfides. Thus, copper mines are often major culprits of acid mine drainage. At some mines, acidic drainage is detected within 2–5 years after mining begins, whereas at other mines, it is not detected for several decades. In addition, acidic drainage may be generated for decades or centuries after it is first detected.
Mining in North Korea handle 10 million tons of zinc ore. Conventional flotation methods are adopted to extract lead and zinc concentrates. Other products from the mine are sphalerite, chalcopyrite, and galena. In gold alone the nation is estimated to hold around 2,000 metric tonnes of reserves, which at a gold value of $1,200/ounce, would give a total worth of $84.6 billion. Other available resources include iron, with 5 billion tonnes of 50% iron-content ore in reserve, nickel, with 36,000 tonnes of the pure metal, and zinc metal, with around 21,100,000 tonnes. The Daebong Mine, located on the border of Gapsan and Woonheung in