Abstract: 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.

Abstract: An energy efficient process is disclosed for the hydrometallurgical oxidation of sulfidic minerals containing copper, silver, nickel, cobalt, molybdenum, or zinc values. A high density slurry, e.g., 67% by weight solids, is prepared from a particulate sulfide mineral and water. Nitrogen dioxide and preferably also oxygen are added to the slurry to oxidize the sulfidic minerals and to produce solubilized cations and nitric oxide. The nitric oxide is oxidized to nitrogen dioxide, thereby regenerating the principal oxidant. If oxygen is added to the slurry along with NO.sub.2, then the regeneration occurs in-situ.

Abstract: Sulfidic minerals containing metal values such as copper, silver, nickel, cobalt, molybdenum, zinc, iron, or mixtures thereof are oxidized with nitrogen dioxide to enable the metal values to be solubilized in an aqueous acidic leach liquor. In practicing the invention, the minerals are added to an aqueous acidic leach liquor and a nitrogen dioxide containing gas is sparged through the slurry to oxidize the metal values. During the reaction, the nitrogen dioxide is reduced to nitric oxide. The nitric oxide is oxidized to nitrogen dioxide by oxygen, either in-situ, or in a separate off-gas oxidizer.

Abstract: A process in which copper, nickel, cobalt and molybdenum are recovered by reducing comminuted raw manganese nodules with an aqueous solution containing cuprous ions. An improvement is disclosed in which copper is oxidized to provide a starting solution of cuprous ions for the process. In one important embodiment of the invention wet copper cement is added to a solution of carbon dioxide and ammonia and ground manganese nodules are then added to the mixture. As a result, a starting solution containing cuprous ions is produced. A major advantage gained from utilizing manganese nodules as an oxidizing agent is that the manganese nodule is itself reduced and its metal values are added to the reaction solution.

Abstract: A process for selectively removing ammonia from an organic solution containing ammonia and an oxime-metal chelate which comprises countercurrently contacting the organic solution with an aqueous solution of ammonium carbonate, ammonium bicarbonate, alkali metal bicarbonate or mixtures thereof. The mole ratio of ammonia, in organic solution prior to contact with the carbonate solution, to carbonate and/or bicarbonate in the fresh aqueous scrub solution is maintained so that ammonia transfer is effected from the organic solution to the aqueous solution. In the fresh scrub solution, the carbonate or bicarbonate concentration is maintained sufficiently high to prevent substantial emulsification of aqueous phase in the organic solution and the ammonia concentration is less than the ammonia concentration in equilibrium with 50 mg/l ammonia in the organic solution.

Abstract: A metal recovery process in which copper, nickel, cobalt and molybdenum are recovered by reducing comminuted raw manganese nodules and leaching the reduced nodules with an aqueous ammoniacal solution to obtain a leach solution containing these metal values. In order to recover copper from leach solutions by techniques such as ion exchange extraction, it is desirable to oxidize the copper to the cupric state.In another embodiment, oxidation is required to bring about the solution of reduced metallic metal values of copper, nickel and cobalt or to convert lower valence ions of these metals to a more highly oxidized state. The present invention is an improvement in the foregoing metal recovery processes. In the present invention manganese nodules are used as the oxidizing agent to oxidize slurries containing pre-reduced manganese nodules which have lower valence ions of metals such as copper or the metal itself.

Abstract: Sodium ions are added to manganese nodules to convert the montmorillonite clay naturally occurring in the nodule material into a bonding agent for pelletization into spherical agglomerates.The addition of coking coal to provide bonding stength after reduction, during which the clay bond is destroyed, is also disclosed.