Method for improving extraction efficiency of copper and zinc in zinc leaching residues through cooperation of ultrasonic waves and manganese dioxide

Abstract

The invention relates to the technical field of hydrometallurgy, and discloses a method for improving the extraction efficiency of copper and zinc in zinc leaching residues through cooperation of ultrasonic waves and manganese dioxide, and the method comprises the following steps: mixing the zinc leaching residues with manganese dioxide and dilute sulphuric acid, and carrying out ultrasonic leaching to obtain a leaching solution containing copper and zinc. According to the method, a passivation layer on the surface of the copper ore is effectively removed through the cavitation effect and the micro-jet effect of ultrasonic waves, and the reaction contact between leaching liquid and the ore is enhanced; high-valence manganese ions generated by manganese dioxide in an acid medium can oxidize copper sulfide and spinel type zinc ferrite, and synchronous and efficient dissolution of copper and zinc is achieved. According to the method, the leaching rate of copper can be remarkably increased under the mild condition, zinc recycling is taken into account, energy consumption is low, and environment friendliness is achieved.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and more specifically, to a method for improving the extraction efficiency of copper and zinc from zinc leaching residue by synergistic use of ultrasonic waves and manganese dioxide. Background Technology

[0002] Copper and zinc are important non-ferrous metal resources. Copper has excellent electrical and thermal conductivity and corrosion resistance, and is widely used in power, electronics, transportation, and machinery manufacturing. Zinc plays an important role in anti-corrosion coatings, alloy manufacturing, and chemical production. With the decreasing availability of high-grade copper and zinc ore resources, the comprehensive recovery of valuable metals from smelting process byproducts has become an important way to obtain these resources.

[0003] In the hydrometallurgical zinc refining process, zinc concentrate is roasted and acid-leached to obtain zinc sulfate solution, which is then purified and electrolyzed to produce metallic zinc. The acid leaching step generates a large amount of zinc leaching residue, a solid waste containing not only residual zinc but also valuable metals such as copper. Copper exists primarily as sulfides (such as CuS and Cu2S), complex sulfides formed with iron, and encapsulated phases associated with oxides or silicates. These minerals have a dense and stable structure, making them difficult to decompose under conventional acid leaching conditions. Simultaneously, iron readily forms precipitates or encapsulation layers with copper during leaching, further reducing copper release efficiency. In contrast, zinc in the residue exists in the form of oxides or spinel-type zinc ferrite (ZnFe2O4), which, while also possessing high chemical stability, reacts slightly less readily under acidic conditions than copper sulfide.

[0004] To improve the leaching rates of copper and zinc in zinc leaching residue, existing technologies often employ high-temperature roasting, chlorination roasting, or the addition of reducing agents (such as hydrogen, carbon monoxide, hydrogen sulfide, ferrous sulfate, etc.) to the acid leaching system to disrupt the structure of insoluble minerals. However, these methods have significant drawbacks: high-temperature oxidation or chlorination roasting consumes a lot of energy and requires large equipment investments, and may result in some copper phases being difficult to recover in subsequent acid leaching; the reduction reaction conditions of hydrogen and carbon monoxide are harsh, posing safety and environmental problems related to the emission of flammable or harmful gases; hydrogen sulfide is highly toxic and corrosive, requiring stringent tail gas treatment; and ferrous sulfate has a slow reaction rate, generating a large amount of iron precipitate, increasing the burden of solid waste treatment. Therefore, a new enhanced leaching technology is needed that operates under mild conditions, achieves high copper leaching rates, and also considers zinc recovery, effectively disrupting the structure of insoluble minerals such as copper sulfide and spinel-type zinc ferrite, thereby achieving efficient recovery of valuable metals from zinc leaching residue. Summary of the Invention

[0005] In view of this, the present invention proposes a method for improving the extraction efficiency of copper and zinc in zinc leaching residue by ultrasound synergistic with manganese dioxide, aiming to solve the problem that the extraction of high-value metal elements in zinc leaching residue in the current technology requires the use of high temperature and other conditions to destroy the insoluble mineral structures such as copper sulfide and spinel-type zinc ferrite on the surface of zinc leaching residue.

[0006] This invention proposes a method for improving the extraction efficiency of copper and zinc from zinc leaching residue using ultrasound-assisted manganese dioxide, comprising the following steps: The zinc leaching residue was mixed with manganese dioxide and dilute sulfuric acid and then ultrasonically leached to obtain a leachate containing copper and zinc.

[0007] Preferably, the amount of manganese dioxide added is 10% to 23% of the mass of the zinc leaching residue.

[0008] Preferably, the solid-liquid ratio of the dilute sulfuric acid to the zinc leaching residue is 5~9 mL:1 g.

[0009] Preferably, the concentration of the dilute sulfuric acid is 1.8~2.2 mol / L.

[0010] Preferably, the ultrasonic leaching time is 120~240 min, and the ultrasonic leaching temperature is 55~95℃.

[0011] Preferably, the power of the ultrasonic leaching is 240~480W.

[0012] Preferably, the zinc leaching residue is a neutral or acidic leaching residue produced during the hydrometallurgical zinc process.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The leaching temperature of this invention is lower than that of traditional oxidative leaching processes, effectively reducing energy consumption and equipment corrosion risks. Avoid using oxidants such as SO2 and H2O2 that are prone to secondary pollution; process wastewater is easy to treat.

[0014] Ultrasonic cavitation and MnO2 chemical oxidation form a synergistic effect. The former promotes mineral dissociation and oxidant diffusion, while the latter provides continuous oxidation capacity. Under the conditions described in this invention, the copper leaching rate can reach more than 90%, and the zinc leaching rate can be increased to more than 75% simultaneously.

[0015] It can effectively treat hydrometallurgical solid waste from different sources, including complex materials such as zinc leaching slag and copper smelting tailings. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the process flow of the method for improving the extraction efficiency of copper and zinc in zinc leaching residue by ultrasound-assisted manganese dioxide as described in this invention. Figure 2The image shows the XRD pattern of the zinc leaching residue raw material used in the embodiments of the present invention. Figure 3 This is a SEM-EDS image of the zinc leaching residue raw material used in the embodiments of the present invention; Figure 4 For the comparison of SEM images of the leaching residues of Comparative Example 1 and Example 1, in which, Figure 4 Images (a), (b), and (c) in the figure are SEM images of Comparative Example 1. Figure 4 In the figure, (d), (e), and (f) are SEM images of Example 1; Figure 5 EDS image and elemental distribution of the leaching residue of Comparative Example 1; Figure 6 EDS image and elemental distribution of the leaching residue from Example 1; Figure 7 XRD patterns of the leaching residues of Example 1 and Comparative Example 1; Figure 8 The images show an infrared comparison of the leaching residues from Example 1 and Comparative Example 1. Detailed Implementation

[0017] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0018] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0020] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0021] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0022] This invention proposes a method for improving the extraction efficiency of copper and zinc from zinc leaching residue using ultrasound-assisted manganese dioxide, comprising the following steps: The zinc leaching residue was mixed with manganese dioxide and dilute sulfuric acid and then ultrasonically leached to obtain a leachate containing copper and zinc.

[0023] In this invention, the amount of manganese dioxide added is 10% to 23% of the mass of zinc leaching residue, preferably 12% to 21%, more preferably 15% to 20%, and even more preferably 16% to 18%.

[0024] In this invention, the solid-liquid ratio of the dilute sulfuric acid to the zinc leaching residue is 5~9:1, preferably 6~8:1, and more preferably 7~8:1.

[0025] In this invention, the concentration of the dilute sulfuric acid is 1.8~2.2 mol / L, preferably 1.85~2.15 mol / L, more preferably 1.9~2.1 mol / L, and even more preferably 2.0 mol / L.

[0026] In this invention, the ultrasonic immersion time is 120-240 min, preferably 130-220 min, more preferably 150-200 min, and even more preferably 170-180 min; the ultrasonic immersion temperature is 55-95℃, preferably 60-90℃, more preferably 65-85℃, and even more preferably 70-80℃.

[0027] In this invention, the power of the ultrasonic leaching is 240~480W, preferably 270~450W, more preferably 300~430W, and even more preferably 350~400W.

[0028] In this invention, the zinc leaching residue is a neutral or acidic leaching residue produced during the hydrometallurgical zinc process.

[0029] In this invention, such as Figure 1 As shown, after the ultrasonic leaching is completed, the mixture is further subjected to a solid-liquid separation step, wherein the filter residue can be used for lead smelting and the filtrate can be further used to extract copper and zinc.

[0030] This invention utilizes the cavitation effect and microjets of ultrasound to effectively remove the passivation layer on the surface of copper minerals, enhancing the reaction contact between the leachate and the minerals. High-valence manganese ions generated from manganese dioxide in an acidic medium oxidize copper sulfide and spinel-type zinc ferrite, achieving simultaneous and efficient leaching of copper and zinc. This method significantly improves the copper leaching rate under mild conditions while also ensuring zinc recovery, and it is energy-efficient and environmentally friendly.

[0031] Example 1 Weigh 30g of zinc leaching residue (hereinafter referred to as zinc leaching residue raw material) that has been dried, pulverized, and sieved through a 180-mesh sieve. The XRD pattern of the dried zinc leaching residue raw material is shown below. Figure 2 As shown. SEM-EDS image of zinc leaching residue raw material. Figure 3 As shown. From Figure 3 The main chemical composition of the zinc leaching residue raw material can be seen to be iron, zinc, lead, sulfur, calcium, silicon, copper, and oxygen. The spatial distribution of lead, calcium, sulfur, and oxygen shows a high correlation, confirming the presence of lead sulfate (PbSO4) and calcium sulfate (CaSO4). Furthermore, zinc, oxygen, and silicon also show similar distributions, indicating the presence of compounds such as silicon oxide (SiO2) and zinc silicate (Zn2SiO4).

[0032] A 2.1 mol / L dilute sulfuric acid solution was measured and mixed with the zinc leaching residue at a liquid-to-solid ratio of 8 ml / g. The amount of manganese dioxide added was 10% of the zinc leaching residue mass. Ultrasonic leaching was performed at a constant temperature of 85℃ with an ultrasonic power of 360 W and a stirring speed of 100 r / min for 180 min. After leaching, the mixture was filtered, and the filter residue was dried to obtain 12.59 g of dry filter residue. The XRD pattern of the dry filter residue is shown below. Figure 7 As shown by the blue line, analysis revealed that the zinc and copper contents in the leachate were 17.58 g / L and 120.78 mg / L, respectively, with zinc and copper leaching rates of 80.15% and 96.99%, respectively. The XRD pattern of the dried filter residue is shown below. Figure 7 As shown by the blue line, it is denoted as UOL.

[0033] Comparative Example 1 Except for the absence of ultrasound, the raw materials and experimental conditions in this comparative example were the same as in Example 1. The leached filter residue was thoroughly dried to obtain 17.28 g of dry filter residue. The XRD pattern of the dry filter residue is shown in Figure 1. Figure 7 The orange line is denoted as CL. The zinc and copper contents in the leachate were 17.58 g / L and 120.78 mg / L, respectively, with zinc and copper leaching rates of 57.28% and 71.87%, respectively. The results indicate that without ultrasound, the leaching rates of zinc and copper decrease.

[0034] pass Figure 2 and Figure 7It can be seen that, compared with the leaching residue of Comparative Example 1, the main components of the zinc leaching residue are both PbSO4 and CaSO4, with a small amount of ZnS. Furthermore, in the XRD pattern of the leaching residue after ultrasonic-assisted manganese dioxide treatment (UOL), the characteristic peak intensities of CaSO4 and PbSO4 are significantly higher than those under conventional conditions (CL), indicating that this method promotes the preferential oxidation of copper minerals and the formation of stable sulfates. Simultaneously, the ZnS peak intensity is reduced, indicating that zinc leaching is also improved but some residue remains. These results demonstrate that this invention, through the synergistic effect of ultrasonic cavitation and manganese dioxide oxidation, can effectively disrupt the mineral encapsulation structure, accelerate the preferential leaching of copper, and achieve simultaneous release of zinc, thereby improving the overall metal recovery efficiency. The XRD analysis results strongly prove that the ultrasonic-assisted manganese dioxide leaching method exhibits excellent efficiency in the extraction of zinc and copper.

[0035] Figure 4 SEM images of the leaching residues obtained in Comparative Example 1 and Example 1 are shown. Figure 4 (a), (b), and (c) in the examples are Comparative Example 1. Figure 4 (d), (e), and (f) in the figure represent Example 1. As can be seen from the figure, the surface of the leaching residue in Comparative Example 1 ( Figure 4 Region (a) 1) in the sample is relatively flat and lacks obvious corrosion or pyrolysis characteristics, indicating that the reaction process is limited. However, the surface of the leaching residue from Example 1 ( Figure 4 Region (d) 2) exhibits a rough and irregular morphology, accompanied by obvious erosion marks and porous structures, reflecting a significant increase in surface porosity. This morphological difference mainly stems from the synergistic effect of ultrasound and manganese dioxide. On the one hand, ultrasound promotes the preferential conversion of copper minerals into soluble sulfates through redox reactions; on the other hand, ultrasonic cavitation and microjets enhance physical fracturing and exfoliation of the inclusion layer. (Comparison) Figure 4 (c) and Figure 4 In Example 1 (f), the mineral particle dispersion was significantly improved, while in Comparative Example 1, particle agglomeration was more pronounced, hindering sufficient contact between the leachate and the reaction interface, which is one of the important reasons for its low copper leaching efficiency. This result further verifies the effectiveness of ultrasound-assisted manganese dioxide treatment in improving copper preferential recovery while also ensuring zinc leaching.

[0036] Figure 5 and Figure 6 EDS images and elemental distributions of the leaching residues from Comparative Example 1 and Example 1 are shown, in which... Figure 5 Response ratio 1, Figure 6Corresponding to Example 1. Elemental distribution results showed that lead compounds were present in both samples, and the spatial distribution characteristics of lead, sulfur, and oxygen indicated that they mainly existed in the form of lead sulfate; simultaneously, the synergistic distribution of sulfur, oxygen, and calcium suggested the formation of calcium sulfate. In contrast, the signals of elements such as iron and zinc were significantly weakened in Example 1, while the contents of lead, silicon, sulfur, and calcium were significantly increased. This result is consistent with XRD analysis, further demonstrating that the present invention, through ultrasonic-assisted manganese dioxide treatment, can preferentially leach copper and promote the simultaneous release of zinc, thereby improving the overall leaching efficiency.

[0037] Figure 8 The figures show a comparison of infrared spectroscopy images of the leaching residues from Example 1 and Comparative Example 1. The images clearly show that the ultrasonic-assisted manganese dioxide leaching process (blue line) significantly alters the phase composition of the zinc leaching residue and effectively promotes the leaching of zinc and copper. As shown in the figure, compared to the original zinc leaching residue (black line) and the conventional leaching residue (red line), the residue treated with ultrasonic assisted leaching exhibits the most significant reduction in characteristic absorption peak intensities. Specifically, the absorption peaks at 3420 cm⁻¹ and 1630 cm⁻¹, attributed to the OH stretching vibration and HOH bending vibration, respectively, are sharply reduced, confirming the removal of a large amount of bound water and hydroxyl compounds from the residue. Furthermore, the absorption peaks near 460 cm⁻¹ associated with metal-oxygen bonds (such as Zn-O) are also significantly reduced. The above changes demonstrate that the strong mechanical force generated by ultrasonic cavitation can break the inert layers such as silicates and iron alum that encapsulate the target metal, greatly improving the mass transfer process and creating a continuously renewed reaction interface for the chemical oxidation of manganese dioxide. The two work synergistically to achieve efficient extraction of zinc and copper in encapsulated or insoluble states.

[0038] Example 2 Weigh 30g of dried zinc leaching residue material that has been sieved through a 200-mesh sieve. Control the initial acidity to 2.1 mol / L and the liquid-to-solid ratio to 8 mL / g. Add dilute sulfuric acid and the zinc leaching residue to the reactor. The amount of manganese dioxide added is 13% of the mass of the zinc leaching residue. Under constant temperature stirring at 85℃ and a stirring speed of 80-100 r / min, and under ultrasonic treatment at 420 W, the leaching time is 180 min. After leaching, filter the residue and dry it at 60℃ for 15 h. The zinc and copper contents in the filtrate are 15.1 mg / L and 114.82 mg / L, respectively, and the zinc and copper leaching rates are 69.29% and 93.07%, respectively.

[0039] Example 3 Weigh 30g of dried zinc leaching residue that has been sieved through a 200-mesh sieve. Add manganese dioxide at 13% of the zinc leaching residue mass. Mix the two and place them in a reactor. Then, add sulfuric acid solution to the container, controlling the initial acidity to 2.1 mol / L and the liquid-to-solid ratio to 8 mL / g. Under constant temperature stirring at 85℃ and a stirring speed of 80-100 r / min, and with ultrasonic treatment at 240 W, leaching is carried out for 180 min. After leaching, filter the residue and dry it at 60℃ for 15 h. The zinc and copper leaching rates are 56.21% and 70.05%, respectively.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction, characterized in that, Includes the following steps: The zinc leaching residue was mixed with manganese dioxide and dilute sulfuric acid and then ultrasonically leached to obtain a leachate containing copper and zinc.

2. The method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction according to claim 1, characterized in that, The amount of manganese dioxide added is 10% to 23% of the mass of the zinc leaching residue.

3. The method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction according to claim 2, characterized in that, The solid-liquid ratio of the dilute sulfuric acid to the zinc leaching residue is 5~9 mL:1 g.

4. A method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction according to claim 2 or 3, characterized in that, The concentration of the dilute sulfuric acid is 1.8~2.2 mol / L.

5. The method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction according to claim 4, characterized in that, The ultrasonic leaching time is 120~240 min, and the ultrasonic leaching temperature is 55~95℃.

6. The method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction according to claim 5, characterized in that, The power of the ultrasonic leaching is 240~480W.

7. The method for improving the extraction efficiency of copper and zinc from zinc leaching residue by ultrasound-assisted manganese dioxide extraction according to claim 6, characterized in that, The zinc leaching residue is a neutral or acidic leaching residue produced during the hydrometallurgical zinc process.

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