摘要 |
Sulfidic minerals containing metal values such as copper, silver, nickel, cobalt, molybdenum, zinc, iron, or mixtures thereof are leached in two stages. In the second stage, preleached minerals are oxidized with nitrogen dioxide to enable the metal values to be solubilized in the aqueous acidic leach liquor in that stage. During the reaction, the nitrogen dioxide is reduced to nitric oxide. The nitric oxide is oxidized to nitrogen dioxide by oxygen. The acidic metal bearing liquor from the second stage flows to a first stage where it preleaches fresh minerals. The metal bearing liquor is delivered from the first stage to metal recovery while preleached minerals are delivered to the second stage.
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