Method for preparing pleonaste from zinc hydrometallurgy iron slag

Abstract

The invention provides a method for preparing pleonaste from zinc hydrometallurgy iron slag, which comprises the following steps: carrying out first acid leaching on the zinc hydrometallurgy iron slag, then adjusting the pH value, and carrying out solid-liquid separation to obtain first leaching slag; the first leaching residues and a magnesium source are mixed and roasted, and roasted clinker is obtained; the roasting clinker is subjected to second acid leaching, solid-liquid separation is conducted, and second leaching residues are obtained; and the second leaching residues are subjected to magnetic separation, and pleonaste is obtained. According to the method, zinc and calcium elements in the zinc hydrometallurgy iron slag are directionally separated through step-by-step leaching and roasting, the iron element is separated and converted into pleonaste with high magnetism and stability, the requirements of high-value fields such as refractory materials are met, and effective separation of the elements and high-value utilization of the zinc hydrometallurgy iron slag are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste treatment, and relates to a method for treating wet zinc-iron slag, and in particular to a method for preparing magnesia-ferrous spinel from wet zinc-iron slag. Background Art

[0002] Hydrometallurgical zinc smelting is a key method in zinc smelting. It converts zinc from zinc ore into high-purity zinc metal through leaching, purification, extraction, and electrolysis. Compared to traditional pyrometallurgical zinc smelting, this process offers lower energy consumption and better environmental adaptability, making it widely used in the zinc smelting industry.

[0003] During the leaching stage of hydrometallurgical zinc smelting, iron from the raw materials enters the leachate. To prevent iron ions from depositing during the electrolysis process and affecting the quality of the cathode zinc, the leachate must be deironed. Common deironing methods include the goethite method and the jarosite method. This deironing process produces a large amount of iron slag, which contains incompletely recovered zinc and concentrated harmful impurities such as arsenic and antimony. The complex distribution of iron in the slag, particularly the coexistence of zinc and iron, makes it difficult to obtain high-quality iron concentrate using traditional magnetic separation methods. Improper handling can significantly impact resource recovery and environmental protection.

[0004] At present, there are two main methods for treating iron slag: pyroreduction and high-temperature high-acid leaching. The pyroreduction process reduces the iron in the iron slag into iron metal through a high-temperature reduction reaction, which can usually recover a certain amount of zinc. However, this method has high energy consumption and is often accompanied by secondary pollution. Although the high-temperature high-acid leaching process can recover zinc in the iron slag, its process is complicated, the leaching efficiency is low, and as the concentration of impurity ions in the leachate increases, the subsequent purification cost increases significantly. In addition, although the existing treatment technology can recover some valuable metals, the treatment of iron slag is mostly concentrated on low-value-added products, such as cement, and its potential value has not been fully realized.

[0005] CN109796049A discloses a method for preparing iron red using iron precipitate slag from the hydrometallurgical zinc smelting process. Fine-grained iron red pigment is prepared through processes such as high-temperature leaching with dilute sulfuric acid, flotation separation of lead and silver, and hydrothermal treatment. The leachate is then recycled to the hydrometallurgical zinc smelting system. Although this process achieves waste slag resource utilization, it has problems such as complex procedures, low conversion efficiency, and high production costs. In addition, the lack of systematic assessment of the zinc and cadmium residues in the goethite slag may lead to excessive heavy metal residues in the iron red product, and there is still an environmental risk.

[0006] CN116287713A discloses a method for treating iron-removing slag from hydrometallurgical zinc smelting. This method involves leaching the iron-removing slag and zinc concentrate with sulfuric acid, synergistically leaching the zinc therein and separating the iron from the iron-removing slag. While this method allows for the recovery of zinc from the iron-removing slag, it still fails to address the resource utilization of the iron-removing slag, resulting in low resource utilization.

[0007] Therefore, efficient separation and targeted transformation of metal resources in iron slag remains an important technical challenge facing the hydrometallurgical zinc smelting process. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for preparing magnesia-ferro spinel from hydrometallurgical zinc slag, which can effectively separate the iron and zinc elements in the hydrometallurgical zinc slag and realize high-value resource utilization of the elements.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for preparing magnesia-ferrocene spinel from hydrometallurgical zinc-iron slag, the method comprising the following steps:

[0011] (1) subjecting the hydrometallurgical zinc slag to a first acid leaching, then adjusting the pH, and performing solid-liquid separation to obtain a first leached slag;

[0012] (2) mixing the first leached residue with a magnesium source and roasting the mixture to obtain roasted clinker;

[0013] (3) subjecting the roasted clinker to a second acid leaching, performing solid-liquid separation, and obtaining a second leached residue;

[0014] (4) subjecting the second leached residue to magnetic separation to obtain magnesia-ferrous spinel.

[0015] The composition of wet zinc smelting iron slag includes iron alum, goethite, sodium alum, zinc ferrite, zinc sulfate, calcium sulfate, etc. The physical phase composition is diverse and contains many impurities, especially iron-containing phases, which are complex in type and structure. The method of the present invention first breaks the iron slag structure of wet zinc smelting iron slag through acid leaching, leaches the zinc element therein, converts it into zinc salt (such as zinc sulfate) and enters the leachate, and then precipitates some of the iron elements remaining in the solution by adjusting the pH, thereby purifying the acid leaching solution and achieving the separation of the zinc element. The leached slag is roasted with a magnesium source to directionally generate a magnesia-iron spinel phase with an inverse spinel structure. In this process, the calcium component (such as calcium sulfate) is converted into calcium oxide; then, through a one-step acid leaching, the calcium component in the roasted material is converted into a soluble calcium salt (such as calcium chloride) to separate the calcium element. The strong magnetic property of the magnesia-iron spinel is utilized to separate a high-purity, high-quality magnesia-iron spinel product.

[0016] The method provided by the present invention directionally separates zinc and calcium elements in wet zinc smelting iron slag through step-by-step leaching and roasting, separates the iron element and converts it into magnesia-ferrous spinel with high magnetism and stability, meets the needs of high-value fields such as refractory materials, and realizes effective separation of elements and high-value utilization of wet zinc smelting iron slag.

[0017] In the present invention, the composition of the hydrometallurgical zinc slag includes: 30-50wt% of iron, 5-25wt% of zinc, 1-8wt% of calcium, 5-15wt% of sulfur, and 10-30wt% of oxygen.

[0018] The iron content in the hydrometallurgical zinc slag is 30-50wt%, for example, it can be 30wt%, 32wt%, 34wt%, 35wt%, 36wt%, 38wt%, 40wt%, 42wt%, 44wt%, 45wt%, 46wt%, 48wt% or 50wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] The zinc content in the hydrometallurgical slag is 5-25wt%, for example, 5wt%, 10wt%, 15wt%, 20wt% or 25wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] The calcium content in the hydrometallurgical iron slag is 1-8wt%, for example, it can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt% or 8wt%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0021] The sulfur content in the hydrometallurgical zinc slag is 5-15wt%, for example, 5wt%, 8wt%, 10wt%, 12wt% or 15wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] The oxygen content in the hydrometallurgical zinc slag is 10-30wt%, for example, it can be 10wt%, 15wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the acid used in the first acid leaching in step (1) comprises sulfuric acid.

[0024] Preferably, the concentration of sulfuric acid is 30-100 g / L, for example, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the liquid-to-solid ratio of the first acid leaching in step (1) is 2-10 mL / g, for example, 2 mL / g, 3 mL / g, 4 mL / g, 5 mL / g, 6 mL / g, 7 mL / g, 8 mL / g, 9 mL / g or 10 mL / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the temperature of the first acid leaching in step (1) is 50-90°C, for example, 50°C, 60°C, 70°C, 80°C or 90°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, a calcium source is used to adjust the pH in step (1).

[0028] Preferably, the calcium source includes any one or a combination of at least two of calcium hydroxide, calcium oxide or calcium carbonate. Typical but non-limiting combinations include a combination of calcium hydroxide and calcium oxide, a combination of calcium oxide and calcium carbonate, a combination of calcium hydroxide and calcium carbonate, or a combination of calcium hydroxide, calcium oxide and calcium carbonate.

[0029] Preferably, the endpoint pH of the pH adjustment in step (1) is 3.5-5.5, for example, it can be 3.5, 3.6, 3.8, 4.0, 4.2, 4.4, 4.5, 4.6, 4.8, 5.0, 5.2, 5.4 or 5.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the magnesium source in step (2) comprises any one or a combination of at least two of magnesium oxide, magnesium hydroxide or magnesium chloride. Typical but non-limiting combinations include a combination of magnesium oxide and magnesium hydroxide, a combination of magnesium hydroxide and magnesium chloride, a combination of magnesium oxide and magnesium chloride, or a combination of magnesium oxide, magnesium hydroxide and magnesium chloride.

[0031] Preferably, in step (2), the molar ratio of the iron element in the first leaching residue to the magnesium element in the magnesium source is (2-3):1, for example, it can be 2:1, 2.2:1, 2.4:1, 2.5:1, 2.6:1, 2.8:1 or 3:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the calcination temperature in step (2) is 1000-1500°C, for example, it can be 1000°C, 1100°C, 1200°C, 1300°C, 1400°C or 1500°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the calcination time in step (2) is 60-150 min, for example, 60 min, 80 min, 100 min, 120 min, 140 min or 150 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the acid used in the second acid leaching in step (3) comprises hydrochloric acid.

[0035] Preferably, the concentration of the hydrochloric acid is 30-100 g / L, for example, it can be 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the liquid-to-solid ratio of the second acid leaching in step (3) is 2-10 mL / g, for example, 2 mL / g, 3 mL / g, 4 mL / g, 5 mL / g, 6 mL / g, 7 mL / g, 8 mL / g, 9 mL / g or 10 mL / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the magnetic separation method in step (4) includes wet magnetic separation and / or dry magnetic separation.

[0038] Preferably, the method further comprises: obtaining a first leachate after the solid-liquid separation in step (1).

[0039] Preferably, the first leachate is used to prepare electrolytic zinc.

[0040] Preferably, the method further comprises: obtaining a second leachate after the solid-liquid separation in step (3).

[0041] Preferably, the second leachate is used to prepare calcium chloride.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The method provided by the present invention solves the problem of high impurity content and selective extraction of valuable components in hydrometallurgical slag. The method is simple and energy-efficient, producing high-value-added magnesia-iron spinel materials. Byproducts are recovered as electrolytic zinc and calcium chloride products, achieving the upgrading and transformation of hydrometallurgical slag from hazardous waste to functional materials. This provides an innovative path for the resource utilization of slag in the hydrometallurgical industry, with significant economic, social, and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a process flow chart of the method for preparing magnesia-ferro spinel from hydrometallurgical zinc-iron slag provided in Example 1;

[0045] Figure 2 This is the X-ray diffraction pattern of the magnesia-iron spinel material prepared in Example 1. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] In order to clearly illustrate the technical solution of the present invention, in a specific embodiment, the composition of the hydrometallurgical slag used includes: 40.6wt% of iron, 19.2wt% of zinc, 3.1wt% of calcium, 10.1wt% of sulfur, 18.2wt% of oxygen, and 8.22wt% of others.

[0048] Example 1

[0049] This embodiment provides a Figure 1 The method for preparing magnesia-ferrocene spinel from hydrometallurgical zinc-iron slag shown in the figure comprises the following steps:

[0050] (1) Leaching wet zinc smelting slag with a sulfuric acid solution with a concentration of 50 g / L, controlling the liquid-solid ratio of the leaching to 4 mL / g, the leaching temperature to 90° C., and the leaching time to 60 min. After the leaching is completed, calcium hydroxide and calcium oxide are added to the leaching system to adjust the pH of the leaching system to 5.2, with a mass ratio of calcium hydroxide to calcium oxide being 1:1, and then filtering to obtain a first leaching residue and a first leachate;

[0051] (2) mixing the obtained first leaching residue with magnesium oxide and roasting the mixture, wherein the molar ratio of the iron element in the first leaching residue to the magnesium element in the magnesium oxide is 2.5:1, and roasting the mixture at 1200° C. for 100 min to obtain roasted clinker;

[0052] (3) leaching the obtained roasted clinker in a hydrochloric acid solution with a concentration of 50 g / L, with a liquid-to-solid ratio of 4 mL / g and a leaching time of 60 min. After the leaching is completed, filtering is performed to obtain a second leaching residue and a second leachate;

[0053] (4) The obtained second leaching residue is subjected to wet magnetic separation to obtain magnesia-ferrous spinel material.

[0054] In this embodiment, the first leachate obtained in step (1) is a zinc sulfate solution, which is electrolyzed to obtain electrolytic zinc; the second leachate obtained in step (3) is a calcium chloride solution, which is crystallized to obtain calcium chloride.

[0055] The XRD pattern of the magnesium-iron spinel material obtained in this example is as follows Figure 2As shown, it can be seen that the magnesia-ferrous spinel material prepared in the present invention is a magnesia-ferrous spinel with an inverse spinel structure and high purity.

[0056] Example 2

[0057] This embodiment provides a method for preparing magnesia-ferromagnesium spinel from hydrometallurgical zinc-iron slag, the method comprising the following steps:

[0058] (1) Leaching the wet zinc smelting slag with a sulfuric acid solution having a concentration of 100 g / L, controlling the liquid-to-solid ratio of the leaching to 2 mL / g, the leaching temperature to 50° C., and the leaching time to 60 min. After the leaching is completed, calcium hydroxide and calcium oxide are added to the leaching system to adjust the pH of the leaching system to 3.5, with a mass ratio of calcium hydroxide to calcium oxide being 1:1, and then filtering to obtain a first leaching residue and a first leachate;

[0059] (2) mixing the obtained first leaching residue with magnesium oxide and roasting the mixture, wherein the molar ratio of the iron element in the first leaching residue to the magnesium element in the magnesium oxide is 2:1, and roasting the mixture at 1500° C. for 60 minutes to obtain a roasted clinker;

[0060] (3) leaching the obtained roasted clinker in a hydrochloric acid solution with a concentration of 30 g / L, with a liquid-to-solid ratio of 10 mL / g and a leaching time of 60 min. After the leaching is completed, filtering is performed to obtain a second leaching residue and a second leachate;

[0061] (4) The obtained second leaching residue is subjected to wet magnetic separation to obtain magnesia-ferrous spinel material.

[0062] In this embodiment, the first leachate obtained in step (1) is a zinc sulfate solution, which is electrolyzed to obtain electrolytic zinc; the second leachate obtained in step (3) is a calcium chloride solution, which is crystallized to obtain calcium chloride.

[0063] Example 3

[0064] This embodiment provides a method for preparing magnesia-ferromagnesium spinel from hydrometallurgical zinc-iron slag, the method comprising the following steps:

[0065] (1) Leaching wet zinc smelting slag with a sulfuric acid solution with a concentration of 30 g / L, controlling the liquid-solid ratio of the leaching to 10 mL / g, the leaching temperature to 70° C., and the leaching time to 60 min. After the leaching is completed, calcium hydroxide and calcium oxide are added to the leaching system to adjust the pH of the leaching system to 5.5, with a mass ratio of calcium hydroxide to calcium oxide being 1:1, and then filtering to obtain a first leaching residue and a first leachate;

[0066] (2) mixing the obtained first leaching residue with magnesium oxide and roasting the mixture, wherein the molar ratio of the iron element in the first leaching residue to the magnesium element in the magnesium oxide is 3:1, and roasting the mixture at 1000° C. for 150 min to obtain a roasted clinker;

[0067] (3) leaching the obtained roasted clinker in a hydrochloric acid solution with a concentration of 100 g / L, with a liquid-to-solid ratio of 2 mL / g and a leaching time of 60 min. After the leaching is completed, filtering is performed to obtain a second leaching residue and a second leachate;

[0068] (4) The obtained second leaching residue is subjected to wet magnetic separation to obtain magnesia-ferrous spinel material.

[0069] In this embodiment, the first leachate obtained in step (1) is a zinc sulfate solution, which is electrolyzed to obtain electrolytic zinc; the second leachate obtained in step (3) is a calcium chloride solution, which is crystallized to obtain calcium chloride.

[0070] Example 4

[0071] This embodiment provides a method for preparing magnesia-ferrous spinel from wet zinc-iron slag. Compared with Example 1, the leaching temperature in step (1) is controlled to 40° C., and the rest is the same as Example 1.

[0072] Example 5

[0073] This embodiment provides a method for preparing magnesia-ferrous spinel from wet zinc-iron slag. Compared with Example 1, the leaching temperature in step (1) is controlled to be 100° C., and the rest is the same as Example 1.

[0074] Example 6

[0075] This embodiment provides a method for preparing magnesia-ferrous spinel from wet zinc-iron slag. Compared with Example 1, the pH value in step (1) is adjusted to 3, and the rest is the same as Example 1.

[0076] Example 7

[0077] This embodiment provides a method for preparing magnesia-ferrous spinel from wet zinc-iron slag. Compared with Example 1, the pH value in step (1) is adjusted to 6, and the rest is the same as Example 1.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing magnesia-ferro spinel from wet zinc-metallurgical slag. Compared with Example 1, step (1) is not performed, and the wet zinc-metallurgical slag is directly used for roasting in step (2). The rest is the same as Example 1.

[0080] Comparative Example 2

[0081] This comparative example provides a method for preparing magnesia-ferro spinel from wet zinc-iron smelting slag. Compared with Example 1, step (2) is not performed, and the first leaching residue is directly used for leaching in step (3). The rest is the same as Example 1.

[0082] Comparative Example 3

[0083] This comparative example provides a method for preparing magnesia-ferro spinel from wet zinc-iron smelting slag. Compared with Example 1, step (3) is not performed, and the roasted clinker is directly subjected to wet magnetic separation. The rest is the same as Example 1.

[0084] The purity of the ferromagnesian spinels obtained in the examples and comparative examples was determined, and the recovery rate of each element in the hydrometallurgical zinc slag was calculated. The results are listed in Table 1.

[0085] Table 1

[0086]

[0087] “ / ” in the table means no data.

[0088] As can be seen from Table 1, the method provided by the present invention can utilize wet zinc smelting iron slag as raw material to prepare magnesia spinel material, and can realize the effective separation of iron, magnesium and calcium elements and the high value utilization of wet zinc smelting iron slag. Compared with Example 1, in Examples 4-7, when the temperature or the end pH value of the acid leaching in step (1) is adjusted, the separation of zinc and iron elements is affected, resulting in a slight decrease in the recovery rate of iron or zinc elements. In Comparative Example 1, the first acid leaching is not performed, so the selective separation of zinc elements cannot be achieved. At the same time, during the rear-end roasting process, zinc elements will replace part of the iron elements and enter the spinel lattice, eventually causing the purity of magnesia spinel to drop sharply; in Comparative Example 2, roasting is not performed, and part of the iron elements enter the solution during the second acid leaching process, and the calcium elements are still present in the form of calcium sulfate without roasting. Only a small part of the second acid leaching process is dissolved in the acid leaching solution, so the recovery of iron and calcium elements cannot be achieved; in Comparative Example 3, the second acid leaching is not performed, the impurity residual rate is high, the purity of magnesia spinel is reduced, and the calcium elements enter the slag phase and are not utilized.

[0089] In summary, the method provided by the present invention can achieve the separation and high-value conversion of valuable elements in hydrometallurgical slag, which helps to improve the resource utilization rate of hydrometallurgical slag and has good economic, social and environmental benefits.

[0090] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing magnesia-ferrocene spinel from hydrometallurgical zinc-iron slag, characterized in that: The method comprises the following steps: (1) subjecting the hydrometallurgical zinc slag to a first acid leaching, then adjusting the pH, and performing solid-liquid separation to obtain a first leached slag; (2) mixing the first leached residue with a magnesium source and roasting the mixture to obtain roasted clinker; (3) subjecting the roasted clinker to a second acid leaching, performing solid-liquid separation, and obtaining a second leached residue; (4) subjecting the second leached residue to magnetic separation to obtain magnesia-ferrous spinel.

2. The method according to claim 1, characterized in that The acid used in the first acid leaching in step (1) comprises sulfuric acid; Preferably, the concentration of the sulfuric acid is 30-100 g / L.

3. The method according to claim 1 or 2, characterized in that Step (1) The liquid-to-solid ratio of the first acid leaching is 2-10 mL / g; Preferably, the temperature of the first acid leaching in step (1) is 50-90°C.

4. The method according to any one of claims 1 to 3, characterized in that The pH adjustment in step (1) uses a calcium source; Preferably, the calcium source includes any one of calcium hydroxide, calcium oxide or calcium carbonate, or a combination of at least two of them.

5. The method according to any one of claims 1 to 4, characterized in that The end point pH of the pH adjustment in step (1) is 3.5-5.

5.

6. The method according to any one of claims 1 to 5, characterized in that The magnesium source in step (2) comprises any one of magnesium oxide, magnesium hydroxide or magnesium chloride, or a combination of at least two thereof; Preferably, in step (2), the molar ratio of the iron element in the first leaching residue to the magnesium element in the magnesium source is (2-3):

1.

7. The method according to any one of claims 1 to 6, characterized in that The calcination temperature in step (2) is 1000-1500° C. Preferably, the calcination time in step (2) is 60-150 min.

8. The method according to any one of claims 1 to 7, characterized in that The acid used in the second acid leaching in step (3) comprises hydrochloric acid; Preferably, the concentration of the hydrochloric acid is 30-100 g / L; Preferably, the liquid-to-solid ratio of the second acid leaching in step (3) is 2-10 mL / g.

9. The method according to any one of claims 1 to 8, characterized in that The magnetic separation method in step (4) includes wet magnetic separation and / or dry magnetic separation.

10. The method according to any one of claims 1 to 9, characterized in that The method further comprises: after the solid-liquid separation in step (1), obtaining a first leachate; Preferably, the first leachate is used to prepare electrolytic zinc; Preferably, the method further comprises: obtaining a second leachate after the solid-liquid separation in step (3); Preferably, the second leachate is used to prepare calcium chloride.

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