Copper-zinc synergistic efficient leaching method for copper oxide ore

Abstract

This invention provides a highly efficient copper-zinc leaching method for copper oxide ores, belonging to the field of hydrometallurgical technology. The invention employs a segmented grinding and leaching design. The first stage, using -2mm coarse-grained leaching, preferentially dissolves easily leached copper oxide and zinc oxide. The second stage involves grinding the ore to -165μm before leaching, utilizing the oxidizing properties of ferric sulfate to dissolve difficult-to-leach sulfides, significantly improving the copper and zinc leaching rates. The total copper leaching rate reaches 79.09%, and the total zinc leaching rate reaches 93.14%. This invention features strong process stability, adapting to the processing needs of copper oxide ores of different grades. The process flow is simple, eliminating the need for complex gravity separation and flotation stages, reducing equipment investment and operating costs. Furthermore, the leaching agent dosage is controllable, making it environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, and particularly relates to a method for efficient copper-zinc synergistic leaching of copper oxide ore. Background Technology

[0002] Copper resources mainly include three categories: copper oxide ores, copper sulfide ores, and mixed copper ores. In recent years, with the continuous mining and utilization of high-quality copper sulfide and copper oxide ores, the development and utilization of complex and difficult-to-process copper oxide ores has attracted much attention, and the research and development of related technologies is now urgent.

[0003] However, copper oxide ores are characterized by high binding rates, fine particle size, severe mudification, and complex mineral composition, making recovery difficult and resulting in low resource utilization. Copper oxide ores are generally enriched through flotation, which is further divided into direct flotation and sulfide flotation. However, direct flotation suffers from poor selective separation between copper oxide minerals and gangue minerals, making it unsuitable for copper oxide ores with complex mineral compositions. Sulfide flotation involves pre-modifying the mineral surface with a sulfiding agent before adding a collector. Through sulfidation, highly reactive copper sulfide components or even a thin film of copper sulfide are generated on the hydrophilic surface of the copper oxide minerals. Then, a flotation process similar to that used for separating copper sulfide ores is employed for recovery and utilization.

[0004] Traditional single flotation or gravity separation processes are difficult to adapt to complex mineral compositions. For example, in raw ore, copper and zinc are associated and there are multiple phases such as free copper oxide, bound copper oxide, and zinc sulfide. Moreover, the ore is severely muddy. In the flotation test, the zinc recovery rate was only 1.21% and the copper recovery rate was 1.47%, which could not achieve effective separation.

[0005] Although the gravity-flotation-leaching combined process has been attempted, the process is complex and lacks specificity. When tin is selected by shaking table, the concentrate grade is only 1.53% and the recovery rate is less than 11%, with a large amount of valuable elements remaining in the middlings and tailings. Summary of the Invention

[0006] This invention provides a method for efficient copper-zinc leaching of copper oxide ore. Through a two-stage leaching design, the first stage of leaching prioritizes the dissolution of easily leached copper oxide and zinc oxide, while the second stage involves grinding the ore to -165μm and then leaching it to dissolve the difficult-to-leach sulfides by utilizing the oxidizing properties of ferric sulfate. This significantly improves the copper and zinc leaching rates, with a total copper leaching rate of 79.09% and a total zinc leaching rate of 93.14%.

[0007] The copper-zinc synergistic high-efficiency leaching method for copper oxide ore according to the present invention includes the following steps: (1) Pretreatment of mineral samples: Take raw copper oxide ore, crush it, and the final mineral particle size is -2mm to obtain pretreated mineral samples; (2) First stage leaching: Construct an acidic leaching system and leach the pretreated mineral sample by stirring for 3-4 hours under the condition of liquid-solid ratio of 4.5-5:1 to obtain first stage leaching residue; (3) Grind the first leaching residue using a ball mill to achieve a grinding concentration of 60-70% and a grinding fineness of -165μm to obtain the ground slurry; (4) Two-stage leaching: The ore slurry after grinding is stirred and leached for 4-5 hours under the condition of sulfuric acid-ferric sulfate oxidation leaching system with a liquid-solid ratio of 5:1.

[0008] Preferably, in the copper oxide ore raw material described in step (1), the Cu content is 0.5-1.0% and the Zn content is 1.5-1.7%.

[0009] Preferably, the acidic leaching system in step (2) is a sulfuric acid solution with a sulfuric acid concentration of 90-95 g / L.

[0010] Preferably, the temperature of the stirring leaching in step (2) is 50-55℃ and the stirring speed is 400-450r / min.

[0011] Preferably, the concentration of sulfuric acid in the sulfuric acid-ferric sulfate oxidative leaching system in step (4) is 74-80 g / L, and the amount of ferric sulfate is added according to the molar ratio of Fe3+ to Cu of 4:1.

[0012] Preferably, the temperature of the stirring leaching in step (4) is 45-50℃ and the stirring speed is 400-450r / min.

[0013] The beneficial effects of this invention are: This invention employs a two-stage leaching design. The first stage prioritizes the dissolution of easily leached copper oxide and zinc oxide, while the second stage involves grinding the ore to -74μm before leaching, utilizing the oxidizing properties of ferric sulfate to dissolve difficult-to-leach sulfides. This significantly improves the copper and zinc leaching rates, achieving a total copper leaching rate of 79.09% and a total zinc leaching rate of 93.14%. This invention features strong process stability, adapting to the processing needs of copper oxide ores of varying grades. The process flow is simple, eliminating the need for complex gravity separation and flotation stages, reducing equipment investment and operating costs. Furthermore, the leaching agent dosage is controllable, making it environmentally friendly. Detailed Implementation

[0014] This invention provides a highly efficient copper-zinc synergistic leaching method for copper oxide ore. In a specific embodiment, the copper oxide ore used is analyzed to determine the distribution of the main phases, including free copper oxide, bound copper oxide, and zinc oxide. The main metallic minerals in this copper oxide ore are limonite and pyrrhotite, with small amounts of chalcopyrite, pyrite, sphalerite, and galena. The gangue minerals are mainly composed of rock fragments, followed by single-element quartz, feldspar, calcite, and pyroxene. The copper oxide ore is taken, air-dried, crushed to -2mm, and after mixing, the composition is determined to be Cu 0.57%, Zn 1.52%, Sn 0.143%, with free copper oxide accounting for 43.86%, bound copper oxide accounting for 47.37%, and zinc oxide accounting for 95.77%.

[0015] The results of multi-element grade analysis of the raw ore are shown in Table 1, and the results of copper phase analysis are shown in Table 2.

[0016] Table 1

[0017] Table 2

[0018] Example 1 A highly efficient copper-zinc synergistic leaching process for copper oxide ore comprises the following steps: (1) Sample pretreatment: 300g of raw copper oxide ore was taken to obtain a pretreated sample with a final mineral particle size of -2mm. 100g of the pretreated sample was taken for water analysis test. The distribution rate of +74μm was 43.62% and the distribution rate of -19μm was 33.19%. (2) First-stage leaching: Take 50g of pretreated ore sample, add sulfuric acid solution, control the liquid-to-solid ratio at 4.7:1, sulfuric acid concentration at 94.28g / L, temperature at 50.83℃, stirring intensity at 420r / min, and leach for 4h; after leaching, filter to obtain 44.25g of first-stage leaching residue, with copper leaching rate of 65.22% and zinc leaching rate of 87.02%; the leaching results are shown in Table 3: Table 3

[0019] (3) Grind the first leaching residue using a ball mill with a grinding concentration of 65% and a grinding fineness of -165μm to obtain the ground slurry; (4) Two-stage leaching: Take 40g of the ground slurry, add a sulfuric acid-ferric sulfate mixed solution, control the liquid-solid ratio at 5:1, the sulfuric acid concentration at 76g / L, m(Fe3+):m(Cu) = 4:1, the temperature at 48℃, the stirring intensity at 420r / min, and leach for 5h; after leaching, filter to obtain 37.06g of leaching residue, with a total copper leaching rate of 79.09% and a total zinc leaching rate of 93.14%. The leaching results are shown in Table 4: Table 4

[0020] Leachate treatment: ICP analysis was performed on the second-stage leachate, and the Cu concentration was 0.0646 g / L and the Zn concentration was 0.033 g / L.

[0021] In this invention, I. Synergistic dissociation mechanism of mineral sample pretreatment Crushing principle: The crusher uses four main forces—compression, impact, shearing, and grinding—to break down the ore's crystal lattice and structural bonds, crushing large pieces of raw ore into particles as small as -2mm. Particle size classification mechanism: Water analysis test showed that copper and zinc are mainly concentrated in the +74μm and -19μm particle size. By separating them, the leaching blind zone caused by fine particle agglomeration and coarse particle undissociation is avoided, thereby improving the reaction efficiency between the target mineral and the leaching agent.

[0022] II. Dissolution Mechanism of Easily Leachable Phases in a Single Leaching Stage Acidic system dissolution: Using sulfuric acid as a leaching agent, an acidic environment is constructed, and the crystal structure of free copper oxide (43.86%), bound copper oxide (47.37%) and zinc oxide (95.77%) is destroyed through protonation, generating soluble sulfates that enter the liquid phase.

[0023] Multi-factor synergistic effect mechanism: Through orthogonal experiments and response surface optimization, the interaction law of sulfuric acid concentration, liquid-solid ratio and temperature was clarified. Sulfuric acid concentration dominates the reaction driving force, liquid-solid ratio ensures mass transfer efficiency, and temperature accelerates ion diffusion. The three factors work together to enable the rapid dissolution of easily leached phases, with copper leaching rate reaching 65.22% and zinc leaching rate reaching 87.02%.

[0024] Grinding principle: Grinding dissociation: By using 65% concentration and grinding fineness of -165μm, the intergrowth structure of limonite, pyrrhotite and chalcopyrite and cuprite is broken, exposing the active sites on the surface of copper and zinc minerals, creating contact conditions for subsequent leaching reactions.

[0025] III. Oxidation and Dissolution Mechanism of Difficult-to-Leach Phases in Two-Stage Leaching The role of the sulfuric acid-ferric sulfate oxidation system: Fe3+ acts as a strong oxidant, preferentially oxidizing secondary copper sulfide and other difficult-to-leach phases in the first stage of leaching residue. It destroys the sulfide lattice through electron transfer, and the reaction formula is (CuFeS2+4Fe3+=Cu2++5Fe2++2S). At the same time, Fe3+ is reduced to Fe2+, maintaining the stability of the redox potential of the system.

[0026] Impurity interference suppression mechanism: By precisely controlling the liquid-to-solid ratio of 5:1, the temperature of 48℃, and the sulfuric acid concentration of 76g / L, the consumption of reagents by galena and sphalerite is reduced, avoiding the formation of lead sulfate precipitates covering the mineral surface; controlling the solution pH value inhibits the Fe3+ hydrolysis reaction (Fe... 3+ +3H₂O=Fe(OH)₃+3H + ), to ensure its oxidation capacity.

[0027] Extended leaching time enhances reaction mechanism: The second-stage leaching is extended to 5 hours to ensure that the difficult-to-leach phases react fully, while avoiding the reaction of malachite with sulfuric acid to form silica gel that hinders mass transfer, further increasing the total copper leaching rate to 79.09%.

[0028] IV. Selective Separation Mechanism of Co-recovery of Copper and Zinc Selective dissolution of phases: The first stage of leaching preferentially dissolves easily leached copper oxide and zinc oxide, while the second stage of leaching specifically oxidizes difficult-to-leach copper sulfide, achieving stepwise and efficient dissolution of copper and zinc phases and avoiding mutual interference.

[0029] Liquid phase enrichment and separation: Copper in the leachate as Cu 2+ Zinc (Zn) 2+ The form exists, and the elemental concentration can be determined by ICP full scan.

[0030] Example 2 A high-efficiency copper-zinc synergistic leaching process for copper oxide ore is proposed. The steps are the same as in Example 1, except that the first-stage leaching time is adjusted to 3 hours and the second-stage leaching temperature is adjusted to 50°C. The final total copper leaching rate is 78.32% and the total zinc leaching rate is 92.57%, which meets the requirements for industrial recycling.

[0031] Example 3 A high-efficiency copper-zinc synergistic leaching process for copper oxide ore is proposed. The steps are the same as in Example 1, except that the sulfuric acid concentration is adjusted to 90 g / L and the liquid-solid ratio is adjusted to 5:1. The final total copper leaching rate is 77.89% and the total zinc leaching rate is 91.83%, with good process stability.

[0032] Comparative Example 1 The copper oxide ore was subjected to flotation using a single flotation process: Process parameters: 300g of raw ore, zinc separation, no pretreatment or parameter optimization, the specific steps are as follows: (1) 300g of raw ore was weighed as flotation raw material and pretreated according to the method of step (1) in Example 1 to obtain slurry; (2) Add 30g / t of No. 2 oil (pine oil) to the slurry in preparation for desliming treatment; stir for 2 minutes to ensure uniform dispersion of the agent, promote the attachment of fine mud particles to air bubbles, and then turn on the aeration system and adjust the aeration volume to 0.2-0.3m. 3 / (m2 ·min), continue scraping the foam until the foam layer becomes thin and the color becomes lighter (no obvious fine mud floats to the surface), stop aeration and scraping the foam, the desliming operation is over, and after the foam layer stabilizes, slowly scrape off the upper foam product with a scraper, which is the deslimed product (fine mud); the remaining material enters the next stage of flotation process; (3) For the remaining material after the first separation, adjust the stirring speed to 1800~2000 r / min and the temperature to 23℃. First, add 60g / t of butyl xanthate and stir for 3min. Then, add 20g / t of No. 2 oil (pine oil) and stir for 1min. Start skimming the foam and continue skimming until the foam layer becomes thin to enhance the floatability of the target mineral and enable the material to complete the final flotation separation, obtaining concentrate (target product) and tailings (remaining waste components). The leaching results are shown in Table 5: Table 5

[0033] Key findings: Copper recovery rate was only 1.47%, and zinc recovery rate was only 1.21%.

[0034] The copper and zinc grades in the tailings were 0.60% and 1.52%, respectively, indicating that almost no effective separation and recovery was achieved.

[0035] Comparative Example 2 The copper oxide ore was flotated using a single gravity separation shaking table process: Process parameters: 1000g of raw ore is separated by shaking table gravity separation, without subsequent leaching or particle size classification. The specific steps are as follows: Using 1000g of ore as the initial material, the first step is to perform a grinding operation, adding 552ml of distilled water to grind the material to a particle size of -74μm, with 70% of the particles reaching this size. This ensures that the mineral particles reach a suitable liberation particle size, creating conditions for subsequent shaking table separation.

[0036] After grinding, the material is fed into a shaking table. Under the synergistic effect of the shaking table, mineral particles of different densities and sizes are separated into layers and zones according to their specific gravity differences, thus achieving physical separation.

[0037] After separation on a shaking table, three typical products are produced based on differences in mineral enrichment and density: Shaking table concentrate: yield 1.00%, Sn grade 1.53%, recovery rate 10.70%; Mid-minerals from shaking table: yield 43.56%, Sn grade 0.13%, recovery rate 38.99%; Shaking table tailings: yield 55.45%, Sn grade 0.13%, recovery rate 50.31%.

[0038] The separation results are shown in Table 6: Table 6

[0039] Key findings: Tin concentrate grade was 1.53%, but recovery rate was only 10.70%.

[0040] The copper recovery rate was 0.99%, with a large amount of copper and tin remaining in the middlings (copper recovery rate 31.87%) and tailings (copper recovery rate 67.14%), resulting in serious waste of resources.

[0041] Comparative Example 3 The copper oxide ore was subjected to flotation using a combined gravity separation-leaching process: Process parameters: 500g of raw ore, using a combined "shaking table-suspension vibration-leaching" process, without optimizing key parameters such as leaching temperature and reagent concentration. The specific steps are as follows: (1) Take 500g of raw ore for grinding, add 276ml of distilled water, grind the material to 70% of the -74μm mesh size, so that the mineral particles can be effectively liberated, providing a suitable particle size for subsequent sorting; (2) After grinding, the ore enters the shaking table equipment for separation. The first shaking table separates the concentrate, middlings and tailings into the second shaking table. The concentrate from the second shaking table merges with the concentrate from the first shaking table, and the tailings from the second shaking table enter the suspension vibration.

[0042] The enriched product from the two-stage shaking table is fed into a suspension sluice (such as a suspension chute) with a vibration frequency of 17.5 Hz and a vibration amplitude of 3.75 mm. This allows for precise selection of fine-grained minerals and effective separation of fine gangue, ultimately yielding a higher-grade suspension concentrate. The suspension tailings are then leached. The experimental results are shown in Tables 7 (shaking table experiment) and 8 (suspension experiment). Table 7

[0043] Table 8

[0044] Key results: Total copper recovery was 30.53% (2.52% from shaking concentrate + 27.25% from suspension concentrate + no additional improvement from leaching), and total tin recovery was 30.56%.

[0045] Comparative Example 4 A single-stage, long-term leaching process at room temperature, with the same mineral sample pretreatment method as in Example 1. (1) Single-stage leaching: Take 50g of pretreated ore sample, add sulfuric acid solution, control the liquid-solid ratio at 4:1, temperature at 23℃, stirring intensity at 420r / min, and leach for 4h; after leaching, filter to obtain 45.59g of leaching residue, with a copper leaching rate of 46.89%; (2) Single-stage leaching: Take 50g of pretreated ore sample, add sulfuric acid solution, control the liquid-solid ratio at 4:1, temperature at 23℃, stirring intensity at 420r / min, and leach for 6h; after leaching, filter to obtain 45.59g of leaching residue, with a copper leaching rate of 52.81%; the leaching results are shown in Table 9: Table 9

[0046] Leaching process parameters: liquid-to-solid ratio 4:1, temperature 23℃, sulfuric acid concentration 80g / L, leaching time 6h, no segmented leaching or temperature control.

[0047] Key results: Copper leaching rate was 52.81%. Although the leaching time was extended, the leaching efficiency was still far lower than the 79.09% achieved by the two-stage leaching method of this invention due to the low temperature.

[0048] Comparative Example 5 A hydrogen peroxide leaching process (using hydrogen peroxide to replace ferric sulfate in Example 1). (1) First stage leaching: Take 50g of pretreated ore sample, add sulfuric acid solution, control the liquid-solid ratio at 4:1, temperature at 40℃, stirring intensity at 420r / min, and leach for 4h; after leaching, filter to obtain 46.54g of first stage leaching residue, with a copper leaching rate of 52.15%; (2) Two-stage leaching: Take 44.1g of the first-stage leaching residue, add sulfuric acid-hydrogen peroxide mixed solution, control the liquid-solid ratio to be 4:1, m(H2O2):m(Cu) = 4:1, temperature 40℃, stirring intensity 420r / min, leaching for 4h; after leaching, filter to obtain 42.07g of leaching residue, copper leaching rate 27.21%.

[0049] (3) Three-stage leaching: Take 40.86g of the first-stage leaching residue, add sulfuric acid-hydrogen peroxide mixed solution, control the liquid-solid ratio at 4:1, m(H2O2):m(Cu) = 4:1, temperature at 40℃, stirring intensity at 420r / min, and leach for 4h; after leaching, filter to obtain 37.91g of leaching residue, copper leaching rate at 17.05%, and total copper leaching rate at 71.11%. The leaching results are shown in Table 10: Table 10

[0050] Key results: The total copper leaching rate was 71.11%, which is lower than the 75.51% of the ferric sulfate oxidation system of this invention.

[0051] Hydrogen peroxide is easily consumed by galena and sphalerite and decomposes easily when heated, resulting in a rapid decrease in effective concentration and poor process stability.

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for efficient copper-zinc synergistic leaching of copper oxide ore, characterized in that, Includes the following steps: (1) Pretreatment of mineral samples: Take raw copper oxide ore, crush it, and control the final mineral particle size to -2mm to obtain pretreated mineral samples; (2) First stage leaching: Construct an acidic leaching system and leach the pretreated mineral sample by stirring for 3-4 hours under the condition of liquid-solid ratio of 4.5-5:1 to obtain first stage leaching residue; (3) Grind the first leaching residue using a ball mill to achieve a grinding concentration of 60-70% and a grinding fineness of -165μm to obtain the ground slurry; (4) Two-stage leaching: The ore slurry after grinding is stirred and leached for 4-5 hours under the condition of sulfuric acid-ferric sulfate oxidation leaching system with a liquid-solid ratio of 5:

1.

2. The method for efficient copper-zinc synergistic leaching of copper oxide ore according to claim 1, characterized in that, In the copper oxide ore described in step (1), the Cu content is 0.5-1.0% and the Zn content is 1.5-1.7%.

3. The method for efficient copper-zinc synergistic leaching of copper oxide ore according to claim 1, characterized in that, The acidic leaching system in step (2) is a sulfuric acid solution with a sulfuric acid concentration of 90-95 g / L.

4. The method for efficient copper-zinc synergistic leaching of copper oxide ore according to claim 1, characterized in that, The temperature of the stirring leaching in step (2) is 50-55℃, and the stirring speed is 400-450r / min.

5. The method for efficient copper-zinc synergistic leaching of copper oxide ore according to claim 1, characterized in that, In step (4), the concentration of sulfuric acid in the sulfuric acid-ferric sulfate oxidative leaching system is 74-80 g / L, and the amount of ferric sulfate used is based on Fe... 3+ It is added at a molar ratio of 4:1 to Cu.

6. The method for efficient copper-zinc synergistic leaching of copper oxide ore according to claim 1, characterized in that, The temperature of the stirring leaching in step (4) is 45-50℃, and the stirring speed is 400-450r / min.

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