Method for stepwise recovery of copper and cobalt from high-copper cobalt dolomite under ammonia system

Abstract

This invention relates to the field of hydrometallurgy, specifically to a method for the stepwise recovery of copper and cobalt from high-copper-cobalt dolomite under an ammonia-based system. The method includes: desulfurization treatment of the high-copper-cobalt dolomite to obtain desulfurized high-copper-cobalt dolomite; ammonia leaching with an ammonia leaching agent to obtain ammonia leaching residue and ammonia leaching solution; ammonium salt co-calcination of the ammonia leaching residue with a roasting agent and additives to obtain roasted copper-cobalt slag; and water leaching of the roasted copper-cobalt slag to obtain water-leached residue and water-leached solution. This invention provides a stepwise recovery process for cobalt-containing dolomite; under mild ammonia leaching conditions, easily leached copper in the ore is preferentially recovered; the ammonium salt co-calcination disrupts the dolomite lattice, converting residual cobalt into soluble chlorides; and cobalt is then recovered through water leaching. The process is short, with low reagent consumption, high metal recovery rate, and environmental friendliness; the use of ammonium bifluoride and potassium chloride as co-calcination additives achieves efficient release and separation of cobalt; it significantly reduces cobalt loss in tailings and improves the comprehensive utilization rate of resources.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgy, specifically to a method for recovering copper and cobalt from high-copper-cobalt dolomite under an ammonia-based system. Background Technology

[0002] Cobalt (Co) is widely used in high-tech fields such as defense, aerospace, and new energy power batteries. Global cobalt resources are highly concentrated, with the Democratic Republic of Congo (DRC) alone accounting for over 55% of global reserves. Meanwhile, in the DRC's metallogenic belt, the proportion of dolomite-type and chlorite-type cobalt deposits has risen to approximately 45%, with a corresponding increase in the proportion of high-calcium and magnesium refractory ores. Cobalt-bearing dolomite has become a key focus and challenge for cobalt resource recovery. In cobalt-bearing dolomite, cobalt often replaces magnesium ions in the dolomite lattice in an isomorphous manner, forming a cobalt-bearing dolomite solid solution. This structural characteristic results in cobalt being uniformly dispersed at the atomic level within the dolomite crystal framework, making effective enrichment through physical beneficiation methods impossible. Chemical means must be used to completely destroy the mineral lattice to release the cobalt.

[0003] Current processing techniques for cobalt-containing dolomite have significant limitations. In the wet leaching stage, while direct acid leaching can dissolve carbonate minerals, the high calcium and magnesium content in dolomite consumes large amounts of acid, resulting in poor economic efficiency. Furthermore, the coexistence of large amounts of calcium and magnesium ions in the leachate increases the difficulty of subsequent cobalt separation and purification. Traditional processes such as ammonium salt roasting-water leaching and reduction roasting-ammonia leaching are ineffective in processing the aforementioned cobalt-containing dolomite, exhibiting low Co leaching rates and high energy consumption. Currently, there is still a lack of efficient and low-cost recovery processes for difficult-to-process ores where cobalt is present in an isomorphic form. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide an efficient method for recovering copper and cobalt from high copper and cobalt dolomite in an ammonia-based system.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammonia-based system, comprising: desulfurizing the high-copper-cobalt dolomite to obtain desulfurized high-copper-cobalt dolomite; adding an ammonia leaching agent and water to the desulfurized high-copper-cobalt dolomite for ammonia leaching to obtain low-copper-cobalt ammonia leaching residue and ammonia leaching solution; adding a roasting agent and additives to the low-copper-cobalt ammonia leaching residue for ammonium salt co-roasting to obtain roasted copper-cobalt slag; adding a reducing agent to the roasted copper-cobalt slag for water leaching to obtain water leaching residue and water leaching solution; copper and cobalt elements are enriched in the ammonia leaching solution and water leaching solution; The ammonia leaching agent includes ammonium sulfate; the mass ratio of ammonium sulfate to the desulfurized high-copper-cobalt dolomite is 1.5~2:1; the ammonia leaching temperature is above 85℃; The calcining agent includes ammonium chloride; the mass ratio of ammonium chloride to the desulfurized high-copper-cobalt dolomite is 1.5~2.5:1; The additives include ammonium bifluoride and potassium chloride; the amount of potassium chloride used is 10wt% to 20wt% of the mass of desulfurized high-copper-cobalt dolomite; the amount of ammonium bifluoride used is 10wt% to 20wt% of the mass of desulfurized high-copper-cobalt dolomite.

[0006] Preferably, the mass ratio of water added during ammonia leaching to the desulfurized high-copper-cobalt dolomite is 2~5:1.

[0007] Preferably, before roasting, the low-copper, high-cobalt ammonia leaching residue is co-ground with the roasting agent and additives.

[0008] Preferably, the temperature for the co-calcination of the ammonium salt is 400~450℃.

[0009] Preferably, the reducing agent includes sodium sulfite; the amount of sodium sulfite used is 1wt% to 5wt% of the mass of the desulfurized high copper-cobalt dolomite.

[0010] Preferably, the water immersion temperature is 70~90℃.

[0011] Preferably, the mass ratio of water used for leaching to desulfurized high-copper-cobalt dolomite is 5~12:1.

[0012] Preferably, the desulfurization treatment employs desulfurization flotation.

[0013] Preferably, the collector used in desulfurization flotation includes n-butyl sodium xanthate.

[0014] Preferably, the frother used in desulfurization flotation includes pine oil.

[0015] Preferably, before desulfurization, high-copper-cobalt dolomite is prepared into a slurry, wherein the content of particles with a particle size of less than 0.074 mm is more than 60 wt%, and the slurry concentration is 50 wt% to 70 wt%.

[0016] Preferably, the desulfurization flotation includes one or more flotation processes.

[0017] Preferably, the flotation time for each stage is 1 to 5 minutes.

[0018] Preferably, the desulfurization flotation includes three stages: the collector dosage in the first stage is 80~160g / t; the frother dosage in the first stage is 10~40g / t; the collector dosage in the second stage is 40~80g / t; the frother dosage in the second stage is 5~20g / t; the collector dosage in the third stage is 5~20g / t; and the frother dosage in the third stage is 1~10g / t.

[0019] The present invention has the following beneficial effects: (1) This invention addresses the differences in the occurrence state and leaching characteristics of copper and cobalt in cobalt-containing dolomite by providing a segmented recovery process of "ammonia leaching - ammonium salt co-roasting - water leaching". First, under mild ammonia leaching conditions, copper that is easily leached from the ore is recovered first, achieving "early recovery" of copper. Then, the ammonia leaching residue is co-roasted with ammonium salts to destroy the dolomite lattice and convert the residual cobalt into soluble chlorides. Finally, cobalt is recovered by water leaching. This process has the advantages of short process, low reagent consumption, high metal recovery rate, and environmental friendliness. (2) Ammonium bifluoride and potassium chloride were used as synergistic roasting additives to achieve efficient release and separation of cobalt. Experimental results showed that after roasting by the method of this invention, the cobalt grade in cobalt-containing dolomite was significantly reduced from about 0.5% in the original ore to about 0.06%, a reduction of about 90%. This data directly proves that the dolomite lattice was effectively destroyed during the roasting process, and the Co in the lattice was released. 2+ By fully exposing and transforming it into a leaching form, this invention significantly reduces cobalt loss in tailings and improves the comprehensive utilization rate of resources. Detailed Implementation

[0020] To make the objectives, solutions, and beneficial technologies of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be noted that the embodiments described in this specification are merely illustrative of the invention and are not intended to limit the invention.

[0021] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0022] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, "multiple" in "one or more" means two or more, and "more than" in "one or more" means two or more.

[0023] Embodiments of the present invention provide a method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammonia-based system, comprising: desulfurizing the high-copper-cobalt dolomite to obtain desulfurized high-copper-cobalt dolomite; leaching the desulfurized high-copper-cobalt dolomite with an ammonia leaching agent and water to obtain low-copper-cobalt ammonia leaching residue and ammonia leaching solution; calcining the low-copper-cobalt ammonia leaching residue with a roasting agent and additives for ammonium salt co-calcination to obtain roasted copper-cobalt slag; leaching the roasted copper-cobalt slag with a reducing agent to obtain water leaching residue and water leaching solution; and enriching copper and cobalt elements in the ammonia leaching solution and water leaching solution. The ammonia leaching agent includes ammonium sulfate; the mass ratio of ammonium sulfate to the desulfurized high-copper-cobalt dolomite is 1.5~2:1; the ammonia leaching temperature is above 85℃; The calcining agent includes ammonium chloride; the mass ratio of ammonium chloride to the desulfurized high-copper-cobalt dolomite is 1.5~2.5:1; The additives include ammonium bifluoride and potassium chloride; the amount of potassium chloride used is 10wt% to 20wt% of the mass of desulfurized high-copper-cobalt dolomite; the amount of ammonium bifluoride used is 10wt% to 20wt% of the mass of desulfurized high-copper-cobalt dolomite.

[0024] This invention employs a "easy-to-recover, early-harvest, segmented recovery" strategy to achieve efficient synergistic extraction of copper and cobalt resources. Addressing the differences in the occurrence states and leaching characteristics of copper and cobalt in cobalt-containing dolomite, it provides a segmented recovery process of "ammonia leaching—ammonium salt co-roasting—water leaching." First, under mild ammonia leaching conditions, easily leached copper from the ore is preferentially recovered, achieving "early copper recovery." Subsequently, the ammonia leaching residue undergoes ammonium salt co-roasting to disrupt the dolomite crystal lattice, converting residual cobalt into soluble chlorides. Finally, cobalt is recovered through water leaching. This "segmented recovery" strategy has the following significant advantages: (1) It can avoid metal interference: Copper may form difficult-to-leach cuprates or react with cobalt in solid solution during subsequent roasting. Prioritizing the recovery of copper can prevent it from being "locked up" in the high-temperature roasting stage and improve the overall recovery rate. (2) It reduces the load of subsequent processing: The early removal of copper greatly simplifies the composition of cobalt leachate and reduces the pressure of impurity separation in the cobalt extraction and purification stage. (3) It achieves "early recovery": The most suitable extraction method is adopted according to the physicochemical characteristics of different metals to avoid the waste of resources or excessive consumption of reagents caused by "one-size-fits-all" processing. It reflects the technical concept of refined and step-by-step utilization of resources.

[0025] This invention significantly improves cobalt extraction efficiency and greatly reduces tailings loss. For the cobalt remaining in the ammonia leaching residue and present in the dolomite lattice in an isomorphic form, this invention uses ammonium bifluoride and potassium chloride as synergistic roasting additives, achieving efficient release and separation of cobalt. Experimental results show that after roasting using the method of this invention, the cobalt grade in cobalt-containing dolomite is significantly reduced from approximately 0.5% in the original ore to approximately 0.06%, a reduction of approximately 90%. This data directly proves that the dolomite lattice is effectively destroyed during roasting, and the Co in the lattice is released. 2+ By fully exposing and transforming it into a leaching form, this invention significantly reduces cobalt loss in tailings and improves the comprehensive utilization rate of resources.

[0026] Fluoride ions (F) - This substance is highly toxic, and related agents should be used with caution. The abundant calcium ions (Ca) in cobalt-containing dolomite... 2+ During the roasting process, it can actively react with F produced by the decomposition of ammonium bifluoride. - The reaction produces highly stable, high-melting-point calcium fluoride (CaF2), achieving in-situ solid fluoride fixation; simultaneously, F - The calcium ions Ca in cobalt-containing dolomite were consumed. 2+ This reduces the difficulty of subsequent purification. In addition, it can (1) reduce equipment corrosion: after fluoride ions are effectively "anchored" by calcium, the corrosion of free hydrogen fluoride (HF) on the roasting reactor, pipeline and tail gas treatment system is reduced, the equipment life is extended and the maintenance cost is reduced; (2) reduce tail gas treatment load: fluoride is fixed in roasting slag, which reduces the emission of toxic fluoride in tail gas, simplifies the tail gas purification process and improves the environmental friendliness of the process; (3) do not consume external fluoride fixation agents: the present invention makes full use of the ore's own components to achieve fluoride fixation, without the need to add additional fluoride fixation agents such as calcium carbonate, which reduces reagent costs and avoids the introduction of unnecessary impurities.

[0027] While ammonium bifluoride disrupts the dolomite lattice, potassium chloride (KCl), acting as a chlorinating agent, provides highly reactive chloride ions (Cl-). - The released cobalt is converted into cobalt chloride (CoCl2), which is easily soluble in water. Ammonium bifluoride and potassium chloride form a synergistic chain of "lattice destruction-chlorination conversion", and neither can be dispensed with. The calcination system is in a chlorination-active atmosphere, which provides favorable conditions for subsequent water leaching extraction.

[0028] This invention organically combines the two-stage process of "heated ammonia leaching" with "ammonium salt co-roasting-water leaching," forming a highly efficient processing flow for copper-cobalt dolomite. Each unit operates under mild conditions (ammonia leaching temperature ≤95℃, roasting temperature 400~450℃), requiring no high-pressure equipment and ensuring controllable energy consumption. The roasting stage uses conventional water leaching to extract cobalt, resulting in a streamlined process. The overall process requires low equipment investment and is easily industrialized, making it particularly suitable for the resource utilization of high-calcium, magnesium, copper-cobalt, and other difficult-to-process oxide ores from regions such as the Democratic Republic of Congo.

[0029] In some embodiments of the present invention, the mass ratio of water added during ammonia leaching to the desulfurized high-copper-cobalt dolomite is 2-5:1.

[0030] In some embodiments of the present invention, the ammonia leaching process is characterized by stirring at 350-400 r / min.

[0031] In some embodiments of the present invention, the ammonia immersion time is 7-9 hours.

[0032] In some embodiments of the present invention, the low-copper, high-cobalt ammonia leaching residue is co-ground with the calcining agent and additives before calcination.

[0033] In some embodiments of the present invention, the co-grinding time is 20-40 minutes.

[0034] In some embodiments of the present invention, the temperature for the co-calcination of the ammonium salt is 400~450°C.

[0035] In some embodiments of the present invention, the synergistic calcination time of the ammonium salt is 50-100 min.

[0036] In some embodiments of the present invention, the reducing agent includes sodium sulfite; the amount of sodium sulfite used is 1wt% to 5wt% of the mass of desulfurized high copper-cobalt dolomite.

[0037] In some embodiments of the present invention, the temperature of the water immersion is 70~90°C.

[0038] In some embodiments of the present invention, stirring at 350-400 r / min is performed during the water immersion process.

[0039] In some embodiments of the present invention, the immersion time is 3 to 6 hours.

[0040] In some embodiments of the present invention, the mass ratio of water used for water immersion to desulfurized high-copper-cobalt dolomite is 5~12:1.

[0041] In some embodiments of the present invention, the desulfurization treatment employs desulfurization flotation.

[0042] In some embodiments of the present invention, the collector used in desulfurization flotation includes n-butylsodium xanthate.

[0043] In some embodiments of the present invention, the frother used in desulfurization flotation includes pine oil.

[0044] In some embodiments of the present invention, high-copper-cobalt dolomite is prepared into a slurry before desulfurization treatment, wherein the content of particles with a particle size of less than 0.074 mm is more than 60 wt% (preferably 70 wt% to 85 wt%), and the slurry concentration is 50 wt% to 70 wt%.

[0045] In some embodiments of the present invention, the desulfurization flotation includes one or more flotation processes.

[0046] In some embodiments of the present invention, the flotation time for each segment is 1 to 5 minutes.

[0047] In some embodiments of the present invention, the desulfurization flotation includes three stages: the collector dosage in the first stage is 80~160 g / t; the frother dosage in the first stage is 10~40 g / t; the collector dosage in the second stage is 40~80 g / t; the frother dosage in the second stage is 5~20 g / t; the collector dosage in the third stage is 5~20 g / t; and the frother dosage in the third stage is 1~10 g / t.

[0048] In some embodiments of the present invention, the Cu content of the high-copper-cobalt dolomite is 2wt%~3wt%.

[0049] In some embodiments of the present invention, the Co content of the high-copper-cobalt dolomite is 0.5wt%~1wt%.

[0050] In some embodiments of the present invention, the Fe grade of the high copper-cobalt dolomite is 1wt%~2wt%.

[0051] In some embodiments of the present invention, the Mn grade of the high copper-cobalt dolomite is less than 0.1 wt%.

[0052] In some embodiments of the present invention, the Mg content of the high copper-cobalt dolomite is 5wt%~10wt%.

[0053] In some embodiments of the present invention, the Ca content of the high copper-cobalt dolomite is 5wt%~15wt%.

[0054] In some embodiments of the present invention, the Al content of the high copper-cobalt dolomite is 3wt%~8wt%.

[0055] In some embodiments of the present invention, the SiO2 content of the high copper-cobalt dolomite is 5wt%~15wt%.

[0056] Example The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.

[0057] The elemental contents of the high-copper-cobalt dolomite in each embodiment and comparative example are as follows: Cu grade 2.3wt%; Co grade 0.764wt%; Fe grade 1.52wt%; Mn grade 0.039wt%; Mg grade 6.68wt%; Ca grade 9.52wt%; Al grade 5.02wt%; SiO2 content 8.08wt%.

[0058] Example 1 The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite under an ammoniacal system in this embodiment includes the following steps: (1) Desulfurization flotation: Take 1000g of the high copper-cobalt dolomite, add 600mL of water, grind and prepare a slurry. The content of particles with a diameter less than 0.074mm in the slurry is 84wt%. The collector used in the desulfurization flotation is n-butyl sodium xanthate and the frother is pine oil. The desulfurization flotation includes three flotation processes: the collector dosage in the first stage is 120g / t, the frother dosage in the first stage is 25g / t, and the flotation time in the first stage is 3min; the collector dosage in the second stage is 60g / t, the frother dosage in the second stage is 10g / t, and the flotation time in the second stage is 2min; the collector dosage in the third stage is 10g / t, the frother dosage in the third stage is 5g / t, and the flotation time in the third stage is 3min. The tailings slurry obtained from the desulfurization flotation is dewatered to obtain desulfurized high copper-cobalt dolomite. (2) Ammonia leaching: Take 10g of desulfurized high copper cobalt dolomite and place it in a beaker. Add 15g of ammonium sulfate and 30g of water. Control the leaching temperature at 90℃, control the stirring speed at 390r / min, and the leaching time at 7h to obtain low copper high cobalt ammonia leaching residue and ammonia leaching solution. (3) Co-calcination of ammonium salts: Take the obtained low copper and high cobalt ammonia leaching residue, add 1.5g ammonium fluoride, 1.5g potassium chloride and 20g ammonium chloride and mix them together. Grind for 35min. The ground sample is then calcined at 430℃ for 70min to obtain calcined copper-cobalt residue. (4) Water leaching: Place the roasted copper-cobalt slag in a beaker, add 90g of water and 0.3g of sodium sulfite, control the leaching temperature at 85℃, control the stirring speed at 390r / min, and the leaching time at 5h to obtain water leaching residue and water leaching liquid; Copper and cobalt are enriched in ammonia leaching solution and water leaching solution; they can be sent to a smelting system for further recovery of copper and cobalt.

[0059] Testing revealed that the Cu content in the desulfurized high-copper-cobalt dolomite was 0.84 wt% and the Co content was 0.591 wt%; the Cu content in the low-copper-high-cobalt ammonia leaching residue was 0.38 wt% and the Co content was 0.522 wt%; and the Cu content in the water leaching residue was 0.12 wt% and the Co content was 0.064 wt%. The overall Cu leaching rate in the desulfurized high-copper-cobalt dolomite was 88.23%, and the overall Co leaching rate was 90.9%, further realizing the comprehensive recovery and utilization of copper and cobalt in the high-copper-cobalt dolomite.

[0060] Example 2 The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite under an ammoniacal system in this embodiment includes the following steps: (1) Desulfurization flotation: Take 1000g of the high copper-cobalt dolomite, add 600mL of water, grind and prepare a slurry. The content of particles with a diameter less than 0.074mm in the slurry is 84wt%. The collector used in the desulfurization flotation is n-butyl sodium xanthate and the frother is pine oil. The desulfurization flotation includes three flotation processes: the collector dosage in the first stage is 120g / t, the frother dosage in the first stage is 25g / t, and the flotation time in the first stage is 3min; the collector dosage in the second stage is 60g / t, the frother dosage in the second stage is 10g / t, and the flotation time in the second stage is 2min; the collector dosage in the third stage is 10g / t, the frother dosage in the third stage is 5g / t, and the flotation time in the third stage is 3min. The tailings slurry obtained from the desulfurization flotation is dewatered to obtain desulfurized high copper-cobalt dolomite. (2) Ammonia leaching: Take 10g of desulfurized high copper cobalt dolomite and place it in a beaker. Add 17g of ammonium sulfate and 35g of water. Control the leaching temperature at 88℃, control the stirring speed at 370r / min, and the leaching time at 8h to obtain low copper high cobalt ammonia leaching residue and ammonia leaching solution. (3) Co-calcination of ammonium salts: Take the obtained low copper and high cobalt ammonia leaching residue, add 1.3g ammonium fluoride, 1.3g potassium chloride and 17.5g ammonium chloride and mix them together. Grind for 25min. The ground sample is then calcined at 440℃ for 80min to obtain calcined copper-cobalt residue. (4) Water leaching: Place the roasted copper-cobalt slag in a beaker, add 80g of water and 0.2g of sodium sulfite, control the leaching temperature at 75℃, control the stirring speed at 360r / min, and the leaching time at 5.5h to obtain water leaching residue and water leaching liquid; Copper and cobalt are enriched in ammonia leaching solution and water leaching solution; they can be sent to a smelting system for further recovery of copper and cobalt.

[0061] Testing revealed that the Cu content in the desulfurized high-copper-cobalt dolomite was 0.84 wt% and the Co content was 0.591 wt%; the Cu content in the low-copper-high-cobalt ammonia leaching residue was 0.35 wt% and the Co content was 0.512 wt%; and the Cu content in the water leaching residue was 0.14 wt% and the Co content was 0.075 wt%. The overall Cu leaching rate in the desulfurized high-copper-cobalt dolomite was 87.53%, and the overall Co leaching rate was 89.87%, further realizing the comprehensive recovery and utilization of copper and cobalt in the high-copper-cobalt dolomite.

[0062] Example 3 The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite under an ammoniacal system in this embodiment includes the following steps: (1) Desulfurization flotation: Take 1000g of the high copper-cobalt dolomite, add 600mL of water, grind and prepare a slurry. The content of particles with a diameter less than 0.074mm in the slurry is 84wt%. The collector used in the desulfurization flotation is n-butyl sodium xanthate and the frother is pine oil. The desulfurization flotation includes three flotation processes: the collector dosage in the first stage is 120g / t, the frother dosage in the first stage is 25g / t, and the flotation time in the first stage is 3min; the collector dosage in the second stage is 60g / t, the frother dosage in the second stage is 10g / t, and the flotation time in the second stage is 2min; the collector dosage in the third stage is 10g / t, the frother dosage in the third stage is 5g / t, and the flotation time in the third stage is 3min. The tailings slurry obtained from the desulfurization flotation is dewatered to obtain desulfurized high copper-cobalt dolomite. (2) Ammonia leaching: Take 10g of desulfurized high copper cobalt dolomite and place it in a beaker. Add 19g of ammonium sulfate and 40g of water. Control the leaching temperature at 92℃, control the stirring speed at 360r / min, and the leaching time at 7.5h to obtain low copper high cobalt ammonia leaching residue and ammonia leaching solution. (3) Co-calcination of ammonium salts: Take the obtained low copper and high cobalt ammonia leaching residue, add 1.7g ammonium fluoride, 1.7g potassium chloride and 22.5g ammonium chloride and mix them together. Grind them together for 30min. The ground sample is then calcined at 410℃ for 90min to obtain calcined copper-cobalt residue. (4) Water leaching: Place the roasted copper-cobalt slag in a beaker, add 100g of water and 0.4g of sodium sulfite, control the leaching temperature at 80℃, control the stirring speed at 375r / min, and the leaching time at 4.5h to obtain water leaching residue and water leaching liquid; Copper and cobalt are enriched in ammonia leaching solution and water leaching solution; they can be sent to a smelting system for further recovery of copper and cobalt.

[0063] Testing revealed that the Cu content in the desulfurized high-copper-cobalt dolomite was 0.84 wt% and the Co content was 0.591 wt%; the Cu content in the low-copper-high-cobalt ammonia leaching residue was 0.34 wt% and the Co content was 0.506 wt%; and the Cu content in the water leaching residue was 0.11 wt% and the Co content was 0.056 wt%. The overall Cu leaching rate in the desulfurized high-copper-cobalt dolomite was 88.92%, and the overall Co leaching rate was 92.44%, further realizing the comprehensive recovery and utilization of copper and cobalt in the high-copper-cobalt dolomite.

[0064] Comparative Example 1 Compared with Example 1, this comparative example does not add potassium chloride during the ammonium salt roasting process, but the other processes are basically the same as in Example 1. Specifically, it includes the following steps: (1) Ammonia leaching: Take 10g of the desulfurized high copper-cobalt dolomite obtained in Example 1 and place it in a beaker. Add 15g of ammonium sulfate and 30g of water. Control the leaching temperature at 90℃, control the stirring speed at 390r / min, and control the leaching time at 7h to obtain low copper-cobalt ammonia leaching residue and ammonia leaching solution. (2) Co-calcination of ammonium salts: Take the obtained low copper and high cobalt ammonia leaching residue, add 1.5g ammonium bifluoride and 20g ammonium chloride, mix and grind for 35min. The ground sample is then calcined at 430℃ for 70min to obtain calcined copper-cobalt residue. (3) Water leaching: Place the roasted copper-cobalt slag in a beaker, add 90g of water and 0.3g of sodium sulfite, control the leaching temperature at 85℃, control the stirring speed at 390r / min, and the leaching time at 5h to obtain water leaching residue and water leaching liquid; Copper and cobalt are enriched in ammonia leaching solution and water leaching solution; they can be sent to a smelting system for further recovery of copper and cobalt.

[0065] Testing revealed that the Cu content in the desulfurized high-copper-cobalt dolomite was 0.84 wt% and the Co content was 0.591 wt%; the Cu content in the low-copper-high-cobalt ammonia leaching residue was 0.37 wt% and the Co content was 0.523 wt%; the Cu content in the water leaching residue was 0.14 wt% and the Co content was 0.1 wt%; the overall Cu leaching rate in the desulfurized high-copper-cobalt dolomite was 86.83%, and the overall Co leaching rate was 86.47%.

[0066] Comparing Comparative Example 1 with Example 1, it can be seen that no potassium chloride was added during the ammonium salt co-calcination process, and the combined leaching rates of copper and cobalt in the desulfurized copper-cobalt dolomite were reduced.

[0067] Comparative Example 2 Compared with Example 1, this comparative example does not add potassium chloride and ammonium bifluoride during the ammonium salt roasting process; other processes are basically the same as in Example 1. Specifically, it includes the following steps: (1) Ammonia leaching: Take 10g of the desulfurized high copper-cobalt dolomite obtained in Example 1 and place it in a beaker. Add 15g of ammonium sulfate and 30g of water. Control the leaching temperature at 90℃, control the stirring speed at 390r / min, and control the leaching time at 7h to obtain low copper-cobalt ammonia leaching residue and ammonia leaching solution. (2) Co-calcination of ammonium salts: Take the obtained low copper and high cobalt ammonia leaching residue, add 20g of ammonium chloride and mix, grind for 35min, and then calcinate the ground sample at 430℃ for 70min to obtain calcined copper-cobalt residue; (3) Water leaching: Place the roasted copper-cobalt slag in a beaker, add 90g of water and 0.3g of sodium sulfite, control the leaching temperature at 85℃, control the stirring speed at 390r / min, and the leaching time at 5h to obtain water leaching residue and water leaching liquid; Copper and cobalt are enriched in ammonia leaching solution and water leaching solution; they can be sent to a smelting system for further recovery of copper and cobalt.

[0068] Testing revealed that the Cu content in the desulfurized high-copper-cobalt dolomite was 0.84 wt%, and the Co content was 0.591 wt%; the Cu content in the low-copper-high-cobalt ammonia leaching residue was 0.37 wt%, and the Co content was 0.521 wt%; the Cu content in the water leaching residue was 0.35 wt%, and the Co content was 0.527 wt%; the overall Cu leaching rate in the desulfurized high-copper-cobalt dolomite was 74.43%, and the overall Co leaching rate was 44.62%.

[0069] Compared with Example 1, this comparative example shows that the ammonium salt roasting process did not add potassium chloride and ammonium bifluoride, which resulted in the copper and cobalt not being leached out in the subsequent water leaching, and the overall leaching rate of copper and cobalt was low.

[0070] Comparative Example 3 This comparative example uses a conventional process of "one-stage ammonia leaching, reduction roasting, and two-stage ammonia leaching," including the following steps: (1) Ammonia leaching: Take 10g of the desulfurized high copper-cobalt dolomite obtained in Example 1 and place it in a beaker. Add 15g of ammonium sulfate and 30g of water. Control the leaching temperature at 90℃, control the stirring speed at 390r / min, and the leaching time at 7h to obtain low copper-cobalt ammonia leaching residue a and ammonia leaching solution b. (2) Reduction roasting: Take the obtained low copper and high cobalt ammonia leaching residue, add 0.5g sodium chloride and 0.5g carbon powder and mix. Roast the sample at 950℃ for 60min to obtain roasted copper-cobalt residue. (3) Two-stage ammonia leaching: Place the roasted copper-cobalt slag in a beaker, add 100g of water and 1g of sodium sulfite, control the leaching temperature at 70℃, control the stirring speed at 390r / min, and the leaching time at 4h. Obtain ammonia leaching residue c and ammonia leaching solution d; Ammonia leaching solution b and ammonia leaching solution d can be sent to the smelting system for further recovery of copper and cobalt.

[0071] Tests showed that the Cu content in low-copper, high-cobalt ammonia leaching residue a was 0.37 wt%, and the Co content was 0.51 wt%; the Cu content in ammonia leaching residue c was 0.40 wt%, and the Co content was 0.491 wt%; and the overall Cu leaching rate in desulfurized high-copper, high-cobalt dolomite was 63.11%, and the overall Cobalt leaching rate was 34.87%.

[0072] Comparing this comparative example with Example 1, it can be seen that the conventional process of adding "one-stage ammonia leaching, reduction roasting, and two-stage ammonia leaching" results in low copper leaching rate and unsatisfactory cobalt leaching effect.

Claims

1. A method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system, characterized in that, include: The high-copper-cobalt dolomite is desulfurized to obtain desulfurized high-copper-cobalt dolomite; the desulfurized high-copper-cobalt dolomite is then leached with ammonia leaching agent and water to obtain low-copper-cobalt ammonia leaching residue and ammonia leaching solution; the low-copper-cobalt ammonia leaching residue is then calcined with roasting agent and additives to obtain calcined copper-cobalt residue; the calcined copper-cobalt residue is then leached with water with a reducing agent to obtain water-leached residue and water-leached solution; copper and cobalt elements are enriched in the ammonia leaching solution and water-leached solution. The ammonia leaching agent includes ammonium sulfate; the mass ratio of ammonium sulfate to the desulfurized high-copper-cobalt dolomite is 1.5~2:1; the ammonia leaching temperature is above 85℃; The calcining agent includes ammonium chloride; The mass ratio of ammonium chloride to the desulfurized high-copper-cobalt dolomite is 1.5~2.5:1; The additives include ammonium bifluoride and potassium chloride; the amount of potassium chloride used is 10wt% to 20wt% of the mass of desulfurized high-copper-cobalt dolomite; the amount of ammonium bifluoride used is 10wt% to 20wt% of the mass of desulfurized high-copper-cobalt dolomite.

2. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1, characterized in that, The mass ratio of water added during ammonia leaching to the desulfurized high-copper-cobalt dolomite is 2~5:

1.

3. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1, characterized in that, Before roasting, the low-copper, high-cobalt ammonia leaching residue is ground together with the roasting agent and additives.

4. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1 or 3, characterized in that, The temperature for the co-calcination of the ammonium salt is 400~450℃.

5. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1, characterized in that, The reducing agent includes sodium sulfite; the amount of sodium sulfite used is 1wt% to 5wt% of the mass of the desulfurized high-copper-cobalt dolomite; the water immersion temperature is 70 to 90°C.

6. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1 or 5, characterized in that, The mass ratio of water used for immersion to desulfurized high-copper-cobalt dolomite is 5~12:

1.

7. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1, characterized in that, The desulfurization treatment employs desulfurization flotation; the collector used in the desulfurization flotation includes sodium n-butyl xanthate; the frother used in the desulfurization flotation includes pine oil.

8. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 1 or 7, characterized in that, Before desulfurization, high-copper-cobalt dolomite is prepared into a slurry, in which the content of particles with a diameter of less than 0.074 mm is more than 60 wt%, and the slurry concentration is 50 wt% to 70 wt%.

9. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 7, characterized in that, The desulfurization flotation includes one or more flotation stages, with each stage having a flotation time of 1 to 5 minutes.

10. The method for stepwise recovery of copper and cobalt from high-copper-cobalt dolomite in an ammoniacal system according to claim 7 or 9, characterized in that, The desulfurization flotation includes three stages: the collector dosage in the first stage is 80~160g / t; the frother dosage in the first stage is 10~40g / t; the collector dosage in the second stage is 40~80g / t; the frother dosage in the second stage is 5~20g / t; the collector dosage in the third stage is 5~20g / t; and the frother dosage in the third stage is 1~10g / t.