Method for producing copper metal from copper concentrates without generating waste

A process for producing copper metal from copper concentrates without generating waste comprising at least the following steps:

• a. conducting an oxidation reaction by feeding a dry, or wet copper concentrate up to 12% of humidity, to a fluidized bed roasting reactor at 650-900° C. using air or oxygen-enriched air between 21 to 100% by volume of oxygen and an excess of oxygen with respect to a required stoichiometric amount for oxidation between 0.001 to 200%, and with a reaction time of 2-12 h;
• b. conducting cleaning and cooling steps by cooling gases generated in the roasting reactor to 400-450° C. in a boiler and cleaning in cyclones and then cooling to 300-320° C. in an evaporative chamber, cleaning outlet gases in an electrostatic precipitator, wherein dust of the precipitator is returned to the roasting reactor and clean gases are washed in a gas washer, and finally sent to an acid plant to produce sulfuric acid;
• c. feeding to a reduction reactor oxidized calcine from the roasting reactor and together with dust generated in the boiler and in the cyclones, are joined and fed to the reduction reactor, adding a reduction agent in an amount equal to or up to 200% excess of the stoichiometric amount required for the reduction reactions, operating at 500-950° C. with a reaction time between 2 to 6 h, using gas containing hydrogen between 10 to 20% volume or coke coal or carbon monoxide with an excess between 0.001 to 200% with respect to the stoichiometric amount required for the reduction reactions;
• d. the entrained dust in the gases from the reduction reactor is separated in cyclones and the dust collected in the cyclones is combined with the calcines of the reduction reactor;
• e. the calcines and dusts of the reduction reactor are mixed with water to form a pulp in a stirred tank operating at a temperature between 20 to 60° C., where the fracturing and release of metallic copper particles trapped in magnetite occurs, wherein the pulp generated in the stirred tank, optionally, is ground in a mill to complete the release of any metallic copper particles trapped in a matrix of magnetite formed during the reduction reaction;
• f. conducting magnetic separation by having the pulp of calcine, dust, and water generated in the stirred tank or from the mill brought to a magnetic separation system in wet drums of one or more stages and with a field density between 18,000 to 20,000 Gauss in which the magnetite is separated from the non-magnetic rest, obtaining a magnetite concentrate
• g. thickening and filtering the magnetic concentrate by having the magnetite concentrate is sent to a thickening step, wherein a underflow of a thickener is fed to a filtering step to obtain a final cake of magnetite concentrate;
• and wherein an overflow of the thickener and filtering of the filter are recirculated to the stirred tank;
• h. conducting flotation of silica and inerts by having the non-magnetic fraction containing the copper and other non-magnetic materials sent to a flotation step, where the silica and inerts are floated at pH between 10 to 10.5 employing collectors and foaming agents with a flotation time of 5 to 8 minutes to generate a pulp with the silica and inerts, and another pulp with the copper;
• i. conducting thickening and filtration of silica and inerts by having the pulp with the silica and inerts thickened in a thickener, wherein the underflow is brought to a filtering step to generate a sterile silica concentrate;
• j. conducting thickening and filtration of a final concentrate containing the copper metal and noble metals by having the pulp with of copper generated in the flotation step thickened in a thickener and the underflow sent to a filtering step, and wherein a metallic copper cake is washed with fresh water in a filter, and a final cake of copper and noble metals is brought to stockpile;
• k. smelting of the final cake of copper and noble metals by loading the stockpile to a smelting furnace in order to obtain metallic copper together with the noble metals dissolved therein, for subsequent electrolytic refining;
• l. recirculating a ground smelting slag to the roasting reactor by having the slag, formed in the smelting stage, cooled and ground in a milling equipment and recirculated to the roasting reactor to recover the copper contained therein.