Process for the selective removal of copper compounds and other impurities with respect to molybdenum and rhenium, from molybdenite concentrates

An industrially scalable process for the selective removal of copper compounds and other impurities with respect to molybdenum and rhenium from a molybdenite (MoS2) concentrate with a copper content of more than 0.5% by dry weight, comprising the following steps:

• (a) mixing a concentrate of impure MoS2 (1) with process water and/or a leaching solution of dilute sulfuric acid in water (2), in which the concentration of sulfuric acid is up to 20 g/l, in a repulping stage (3), to obtain a first pulp (4) with a solid content in the pulp of 50% to 20% by weight, maintaining a ratio of liquid to solid in the range of 1/1 to 4/1, volume/weight;
• (b) leaching the first pulp (4) inside a pressure reactor, in a pressurized leaching stage (6) under an oxidizing atmosphere, with an oxygen-bearing gas (5), at a leaching temperature between 110° C.-180° C. with a partial pressure for the oxidizing gas inside the reactor between 20-150 psig (0.1-1.0 MPa) to obtain a second pulp (7) containing a cleaned molybdenite concentrate and a mother liquor containing dissolved impurities, including sulfuric acid that was generated in situ by the selective oxidation of sulfur contained in the sulfides that initially comprised the impurities in the molybdenite concentrate;
• (c) carrying the second pulp (7) to a cooling tank (8), to obtain a third pulp (7a) with a temperature of at most 60° C.;
• and
• (d) carrying the third pulp (7a) to a solid/liquid separation stage (9) to obtain a clean molybdenite concentrate (10) with a percentage of copper of less than 0.5% by weight and a liquor (11) containing the copper and impurities in solution produced by chemical reactions in the pressurized leaching stage (6).