Method for cooperatively leaching vanadium and lithium from vanadium shale and lithia mica

Abstract

This invention belongs to the field of metal production or refining technology, and discloses a method for co-leaching vanadium and lithium from vanadium shale and lepidolite. The method includes: mechanically activating lepidolite and vanadium shale, and adjusting the carbon content of the vanadium shale; co-calcining the mechanically activated mixture to obtain calcined clinker; and leaching the calcined clinker in an acid solution to obtain a leachate and leaching residue. This invention combines mechanical activation and high-temperature calcination, which improves the leaching rate of lithium and vanadium while reducing acid and energy consumption. Furthermore, the leaching residue has low acidity and does not produce acidic waste residue.

Description

Technical Field

[0001] This invention relates to the field of metal production or refining technology, and in particular to a method for the synergistic leaching of vanadium and lithium from vanadium shale and lithium mica. Background Technology

[0002] Vanadium and lithium are two key elements in the new energy industry. Vanadium shale ore primarily contains vanadium mica, an important mineral for vanadium extraction. For vanadium extraction from vanadium shale, relevant literature often employs methods such as acid roasting and salt roasting, which face problems such as high acid consumption, waste residue (especially acidic waste residue (hazardous waste)) treatment, and the generation of polluting volatile gases. Similarly, lepidolite is an important mineral for lithium extraction. For lithium extraction from lepidolite ore, relevant literature often employs methods such as acid roasting and salt roasting, which also face problems such as high acid consumption and waste residue (especially acidic waste residue (hazardous waste)) treatment.

[0003] Currently, most leaching methods involving vanadium shale and lepidolite involve acid roasting or salt roasting.

[0004] Chinese patent application CN117776231A discloses a method for preparing lithium carbonate by roasting lepidolite composite sulfate. The method involves first mixing lepidolite with sulfate and roasting to obtain a roasted material; then leaching lithium ions from the roasted material in a leaching agent to obtain a lithium-containing leachate; finally, adding a sodium carbonate solution to the lithium-containing leachate and stirring to react, thereby obtaining lithium carbonate. However, this process requires the addition of composite sulfate during roasting, increasing the material flow rate and the amount of lepidolite leaching residue. Furthermore, the roasting process generates fluorine- and sulfide-containing waste gases.

[0005] Chinese patent application CN118639032A discloses a method for low-temperature calcination of spodumene and lepidolite with sulfuric acid to extract lithium. First, lepidolite concentrate and spodumene concentrate are uniformly mixed and then roasted at high temperature to obtain a roasted material. Next, the roasted material is uniformly mixed with sulfuric acid and calcined at a low temperature to obtain an acidified material. Finally, the acidified material is placed in water for leaching and solid-liquid separation to obtain a lithium leachate and lithium leaching tailings. However, this process requires the use of sulfuric acid to calcine the lepidolite, and the leaching residue is acidic waste (hazardous waste).

[0006] Chinese patent application CN110029235A discloses a method for leaching vanadium from vanadium-bearing shale ore. The method involves first mixing vanadium-bearing shale ore powder with concentrated sulfuric acid and then aging it to obtain an aged material. Water is then added to the aged material, and hydrothermal leaching is performed, followed by solid-liquid separation to obtain a vanadium-containing leachate and leaching residue. However, this process involves acidification roasting with concentrated sulfuric acid, resulting in acidic waste residue (hazardous waste). Furthermore, the use of sulfuric acid / concentrated sulfuric acid as an additive requires highly corrosion-resistant equipment, and it generates acidic wastewater and waste residue.

[0007] In summary, the inventors recognize that: salting roasting increases material flow rate and increases the amount of lepidolite leaching residue (lithium loss), and the roasting process generates fluorine- and sulfide-containing waste gas. Using sulfuric acid / concentrated sulfuric acid as a roasting additive requires highly corrosion-resistant equipment and generates acidic wastewater and waste residue (hazardous waste).

[0008] In view of this, the present invention is proposed. Summary of the Invention

[0009] According to one embodiment of the present invention, the objective is to provide a method for the synergistic leaching of vanadium and lithium from vanadium shale and lepidolite. This method combines mechanical activation and high-temperature roasting, and controls the carbon content to cause the lithium-containing mineral crystal structure of lepidolite and the vanadium-containing mineral crystal structure of vanadium shale to break down, thereby increasing the leaching rate of lithium and vanadium while reducing acid and energy consumption.

[0010] The above objective can be achieved through the following technical solutions: According to one aspect of the present invention, a method for co-leaching vanadium and lithium from vanadium shale and lithium mica is provided, comprising: The lepidolite and vanadium shale were mechanically activated, and the carbon content of the vanadium shale was adjusted. The mechanically activated mixture is then co-calcined to obtain calcined clinker; The roasted calcined material is leached in an acidic solution to obtain leachate and leachate residue.

[0011] Preferably, the carbon content of the vanadium shale is controlled to be ≥8%.

[0012] Furthermore, when the carbon content of the vanadium shale is less than 8%, carbon is introduced to make its carbon content ≥ 8%, wherein the carbon is one or more of coke and anthracite.

[0013] Preferably, after mechanical activation, the particle size of the material is less than 50 μm. More preferably, after mechanical activation, the particle size of the material is less than 25 μm.

[0014] Preferably, the mass ratio of lepidolite to vanadium shale in the mixture is 1:5-5:1. More preferably, the mass ratio of lepidolite to vanadium shale in the mixture is 3:5-5:3.

[0015] Preferably, in the step of co-calcining the mechanically activated mixture, the calcination temperature is 850℃-950℃. More preferably, the calcination temperature is 870℃-900℃. Preferably, in the step of co-calcining the mechanically activated mixture, the calcination time is 0.5-3 hours, and more preferably, the calcination time is 1-2 hours.

[0016] Preferably, in the step of leaching the roasted clinker in an acid solution, the acid solution is a low-concentration acid solution, and further, the acid concentration of the acid solution is not higher than 45%.

[0017] Preferably, the acid solution is an inorganic acid or an organic acid.

[0018] Preferably, when the acid solution is an inorganic acid, the concentration of the inorganic acid is 0.5%-45%. More preferably, the concentration of the inorganic acid is 10%-35%.

[0019] Preferably, when the acid solution is an organic acid, the concentration of the organic acid is 0.5%-25%. More preferably, the concentration of the organic acid is 15%-20%.

[0020] Preferably, the inorganic acid is selected from sulfuric acid and nitric acid.

[0021] Preferably, the organic acid is selected from one or more of citric acid, oxalic acid, acetic acid, and formic acid.

[0022] Preferably, in the step of leaching the roasted clinker in an acid solution, the liquid-to-solid ratio of the leaching system is 5:1-10:1.

[0023] Beneficial effects: The method for synergistic leaching of vanadium and lithium from vanadium shale and lepidolite provided by this invention combines mechanical activation and high-temperature roasting to break the crystal structure of lithium-containing minerals in lepidolite and vanadium-containing minerals in vanadium shale, thereby synergistically leaching vanadium and lithium, improving the leaching rate of lithium and vanadium, and reducing acid consumption. This method is simple, produces leaching residue with low acidity, and does not generate acidic waste residue, making it suitable for industrial applications.

[0024] Compared with the prior art, the present invention has the following advantages.

[0025] 1) Mechanical activation is first used to initially disrupt the crystal structure of vanadium shale and vanadium mica. Considering that the carbon content in vanadium shale is usually low and the heat generated is insufficient to meet the process requirements, the carbon content is controlled at a specific value (for example, when the carbon content in vanadium shale is low, only some carbon is added) to obtain higher and more uniform heat in the roasting system, thereby further disrupting the crystal structure of vanadium shale and vanadium mica and improving the subsequent vanadium and lithium leaching rate.

[0026] 2) This method involves high-temperature roasting of mechanically activated materials without the addition of other additives, such as sulfates or sulfuric acid additives. It solves the problems associated with existing salt-based roasting processes, such as the roasting process using compound sulfates (Chinese patent application CN117776231A), which increases material flow, leading to increased lepidolite leaching residue and the generation of fluorine- and sulfide-containing waste gases. It also addresses the issues of high equipment corrosion resistance requirements and hazardous waste generation associated with using sulfuric acid as a roasting additive.

[0027] 3) The acid used in the leaching process is an inorganic or organic acid, and the concentration of the acid in the leaching system is relatively low. This avoids the problems associated with traditional high-concentration sulfuric acid leaching processes, such as high requirements for equipment corrosion resistance and the generation of hazardous waste such as acidic wastewater and waste residue.

[0028] 4) Combining vanadium extraction from vanadium shale with lithium extraction from lepidolite allows for the synergistic extraction of vanadium and lithium by the two minerals. This fully utilizes the calorific value of vanadium shale ore and reduces energy and acid consumption. The interaction between the two minerals is more conducive to the destruction of the crystal structure and the release of vanadium and lithium, which in turn improves the subsequent leaching rate of vanadium and lithium. Attached Figure Description

[0029] Figure 1 This is a schematic flowchart of a method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica in one embodiment of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] The inventors recognized that the salt-roasting process increases material flow and the amount of lepidolite leaching residue, and also generates fluorine- and sulfide-containing waste gas during roasting. Furthermore, using sulfuric acid / concentrated sulfuric acid as a roasting additive requires highly corrosion-resistant equipment and generates acidic wastewater and hazardous waste. Therefore, this invention proposes a method for the synergistic leaching of vanadium and lithium by combining vanadium extraction from vanadium-bearing minerals with lithium extraction from lepidolite. First, mechanical activation is used to initially disrupt the crystal structure of vanadium shale and vanadium mica, and the carbon content of the vanadium shale is controlled. Then, direct high-temperature roasting (without the need for other roasting additives) allows for high and uniform heat distribution within the roasting system, further disrupting the crystal structure of vanadium shale and vanadium mica. By combining mechanical activation and high-temperature roasting, the crystal structures of lithium-bearing minerals in lepidolite and vanadium-bearing minerals in vanadium shale fracture, improving the subsequent leaching rates of lithium and vanadium. Based on the calcined clinker obtained after mechanical activation and high-temperature roasting, the present invention can use low-concentration inorganic or organic acid leaching. The concentration of acid used in the leaching system is low, which reduces acid consumption. The leaching residue has low acidity and will not produce hazardous waste such as acidic waste residue.

[0032] In some embodiments of the present invention, a method for the co-leaching of vanadium and lithium from vanadium shale and lithium mica is provided, such as... Figure 1 As shown, it includes the following steps.

[0033] 1) Mechanically activate the lithium mica and vanadium shale feedstocks and adjust the carbon content of the vanadium shale.

[0034] This invention employs mechanical activation before high-temperature roasting to initially disrupt the crystal structures of vanadium shale and vanadium mica. This is followed by high-temperature roasting, which causes the crystal structures of lithium-containing minerals in lepidolite and vanadium-containing minerals in vanadium shale to fracture, thereby facilitating the subsequent leaching of vanadium and lithium and increasing the leaching rates of vanadium and lithium.

[0035] The purpose of controlling the carbon content in the system is to increase the local temperature within the roasting system, causing the crystal structure of lithium-bearing minerals in lepidolite or vanadium-bearing minerals in vanadium shale to fracture, thus facilitating the subsequent leaching of vanadium and lithium. Furthermore, the carbon content of the vanadium shale ore is controlled to be no less than 8%. Typically, the carbon content of vanadium shale ore ranges from 0.5% to 20%. When the carbon content is below 8%, the heat generated is insufficient to meet the process requirements. By adding an appropriate amount of carbon, such as coke or anthracite, the carbon content of the system is brought to the set value of no less than 8%. This ensures that the roasting system receives higher and more uniform heat during subsequent high-temperature roasting, thereby promoting further disruption of the crystal structure of vanadium shale and vanadium mica.

[0036] To achieve better activation results, after mechanical activation, the particle size of the material is made less than 50 μm, preferably less than 25 μm.

[0037] Furthermore, the two minerals can be mechanically activated separately and then mixed; alternatively, they can be mixed in a specific ratio before mechanical activation. The mixing ratio of the two minerals / mechanically activated material is 1:5-5:1 by mass, preferably 3:5-5:3 by mass, of lepidolite to vanadium shale.

[0038] 2) The mechanically activated mixture is co-calcined to obtain calcined clinker.

[0039] Based on the carbon content-controlled and mechanically activated mixture, high-temperature roasting is employed to fracture the crystal structures of lithium-bearing minerals in lepidolite and vanadium-bearing minerals in vanadium shale, thereby improving the subsequent vanadium and lithium leaching rates and reducing the concentration of acid used in the leaching process. Specifically, the high-temperature roasting temperature is 850℃-950℃, preferably 870℃-900℃; the roasting time is 0.5-3 hours, preferably 1-2 hours. The inventors noted that when the temperature is below 850℃, the leaching rates of vanadium and lithium decrease significantly.

[0040] In this invention, the mixture after carbon content regulation and mechanical activation can be directly roasted at high temperature without the need to add roasting additives such as sulfates or sulfuric acid. This overcomes a series of problems existing in current roasting processes that require the addition of additives such as salts or sulfuric acid. For example, existing processes using sulfuric acid / concentrated sulfuric acid as roasting additives have high requirements for equipment corrosion resistance and generate acidic wastewater and waste residue (hazardous waste). For example, existing salting roasting processes increase the material flow rate, which increases the amount of lithium mica leaching residue, resulting in a decrease in lithium leaching rate. In addition, the roasting process generates fluorine-containing and sulfide-containing waste gas.

[0041] 3) The roasted calcined material is leached in a low-concentration acid solution.

[0042] To further improve the leaching rate of vanadium and lithium, the liquid-solid ratio of the leaching system is controlled to be 5:1-10:1.

[0043] The roasted clinker is leached using a low-concentration acid solution, where the concentration of the acid solution is no higher than 45%. Compared with existing technologies, this invention reduces acid consumption due to the use of mechanical activation and synergistic roasting. The lower concentration of acid used in the leaching system also avoids the adverse effects caused by using high-concentration sulfuric acid / concentrated sulfuric acid, such as equipment corrosion and the generation of hazardous waste such as acidic wastewater and waste residue.

[0044] Furthermore, the acid solution is selected from one or more inorganic acids or organic acids. For example, the acid solution can be an inorganic acid, selected from sulfuric acid solution or nitric acid; or, the acid solution can be an organic acid, selected from one or more citric acid, oxalic acid, acetic acid, and formic acid. For example, when it is a mixture of organic acids, the ratio of citric acid:oxalic acid:acetic acid:formic acid can be (0-1):(0-6):(0-3):(0-1), and the specific amount can be adjusted appropriately according to the properties of the ore.

[0045] When using inorganic acid leaching, the concentration of the inorganic acid is 0.5%-45%, which is lower than that of existing technologies. Preferably, the concentration of the inorganic acid is 10%-35%. This is because mechanical activation and synergistic roasting reduce acid consumption. Furthermore, based on the aforementioned lower concentration of inorganic acid leaching, the problem of high corrosion resistance requirements on equipment due to high-concentration acids is overcome while ensuring the leaching rates of vanadium and lithium.

[0046] When using organic acid leaching, the concentration of the organic acid is 0.5%-25%, preferably 15%-20%. While organic acid leaching achieves slightly lower leaching rates for vanadium or lithium compared to inorganic acid leaching, it is less corrosive to equipment at the same mass concentration. Although existing technologies can achieve good leaching rates using high-concentration acids, they generate acidic wastewater / residue. This invention addresses these problems associated with high-concentration acids while ensuring a high leaching rate.

[0047] The technical solutions and effects of the present invention will be further described and explained below with reference to specific embodiments and comparative examples.

[0048] Example 1

[0049] The following steps are used for the co-leaching of vanadium and lithium from vanadium shale and lithium mica: In the raw ore, lepidolite contains 1.5% Li2O, and vanadium shale contains 12% carbon and 51.7% V2O.

[0050] The materials were mechanically activated separately, with a particle size of less than 25 μm. They were then mixed evenly at a mass ratio of lepidolite to vanadium shale of 1:1. The mixture was then placed in a muffle furnace for calcination at 900℃ for 2 hours. The calcined material was then allowed to cool naturally.

[0051] The clinker was leached in a 35% sulfuric acid solution at a liquid-to-solid ratio of 5 ml: 1 g for 3 hours. The leaching slurry was then filtered to obtain the leachate and leaching tailings.

[0052] Analysis and testing showed that in Example 1, the leaching rate of Li was 94.38% and the leaching rate of V was 91.76%.

[0053] Example 2

[0054] The following steps are used for the co-leaching of vanadium and lithium from vanadium shale and lithium mica: In the raw ore, lepidolite contains 1.5% Li2O, and vanadium shale contains 12% carbon and 51.7% V2O.

[0055] The materials were mechanically activated separately, with a particle size of less than 25 μm. They were then mixed evenly at a mass ratio of lepidolite to vanadium shale of 1:1. The mixture was then placed in a muffle furnace for calcination at 900℃ for 2 hours. The calcined material was then allowed to cool naturally.

[0056] The clinker was leached in a 20% organic acid mixture at a liquid-to-solid ratio of 5 ml: 1 g. The organic acid mixture was a mixture of citric acid, oxalic acid and acetic acid in a ratio of 1:6:3. The leaching time was 3 hours. The leaching slurry was filtered to obtain leachate and leaching tailings.

[0057] Analysis and testing showed that in Example 2, the leaching rate of Li was 91.42% and the leaching rate of V was 88.62%.

[0058] Example 3

[0059] The following steps are used for the co-leaching of vanadium and lithium from vanadium shale and lithium mica: In the raw ore, lepidolite contains 1.4% Li₂O, vanadium shale contains 2.0% carbon, and V₂O₅ contains 1.9%. An appropriate amount of coke is first added to bring the carbon content of the vanadium shale to 15%.

[0060] Lithium mica and vanadium shale were mixed at a mass ratio of 1:1, followed by mechanical activation. The particle size of the mixture after mechanical activation was less than 25 μm. The mixture was then placed in a muffle furnace for calcination at 920℃ for 2 hours. The calcined material was then allowed to cool naturally.

[0061] The clinker was leached in a 30% sulfuric acid solution at a liquid-to-solid ratio of 10 ml: 1 g for 3 hours. The leaching slurry was then filtered to obtain the leachate and leaching tailings.

[0062] Analysis and testing showed that in Example 3, the leaching rate of Li was 94.50% and the leaching rate of V was 92.10%.

[0063] Example 4

[0064] The following steps are used for the co-leaching of vanadium and lithium from vanadium shale and lithium mica: In the raw ore, lepidolite contains 1.5% Li₂O, vanadium shale contains 5% carbon, and V₂O₅ contains 1.7%. An appropriate amount of anthracite is first added to bring the carbon content of the vanadium shale to 8%.

[0065] The materials were mechanically activated separately, with a particle size of less than 25 μm. They were then mixed evenly at a mass ratio of lepidolite to vanadium shale of 1:1. The mixture was then placed in a muffle furnace for calcination at 850℃ for 2 hours. The calcined material was then allowed to cool naturally.

[0066] The clinker was leached in a 40% sulfuric acid solution at a liquid-to-solid ratio of 5 ml: 1 g for 3 hours. The leaching slurry was then filtered to obtain the leachate and leaching tailings.

[0067] Analysis and testing showed that in Example 4, the leaching rate of Li was 94.15% and the leaching rate of V was 91.05%.

[0068] Example 5

[0069] The following steps are used for the co-leaching of vanadium and lithium from vanadium shale and lithium mica: In the raw ore, lepidolite contains 1.6% Li2O, and vanadium shale contains 10% carbon and 1.6% V2O.

[0070] The materials were mechanically activated separately, with a particle size of less than 25 μm. They were then mixed evenly at a mass ratio of 5:1 for lepidolite and vanadium shale. The mixture was then placed in a muffle furnace for calcination at 860℃ for 2 hours. The calcined material was then allowed to cool naturally.

[0071] The clinker was leached in an 18% organic acid mixture at a liquid-to-solid ratio of 8 ml: 1 g. The organic acid mixture was a mixture of citric acid, oxalic acid, acetic acid and formic acid in a ratio of 1:2:1:1. The leaching time was 3 hours. The leaching slurry was then filtered to obtain the leachate and leaching tailings.

[0072] Analysis and testing showed that in Example 5, the leaching rate of Li was 90.01% and the leaching rate of V was 87.89%.

[0073] Comparative Example 1

[0074] This comparative example provides a method for leaching lepidolite and vanadium shale, which differs from the method in Example 1 in that the vanadium shale in the raw ore has a low calorific value and is a low-carbon vanadium shale with a carbon content of only 1.5%.

[0075] Analysis and testing showed that in Comparative Example 1, the leaching rate of Li was 78.19% and the leaching rate of V was 81.62%.

[0076] When the vanadium shale is low-carbon and no carbon content is controlled, the heat generated cannot cause the mineral crystal structure to break more thoroughly / effectively. As a result, the leaching rates of vanadium and lithium are low when leached with the same low-concentration inorganic acid solution.

[0077] By comparing Comparative Example 1 with Example 1 or Example 3, which is also a low-carbon vanadium shale, it can be seen that: by controlling the carbon content of vanadium shale, the present invention can obtain higher and more uniform heat in the roasting system during high-temperature roasting, which is more conducive to the fracture of the lithium-bearing mineral crystal structure of lepidolite and the vanadium-bearing mineral crystal structure of vanadium shale, thereby improving the vanadium and lithium leaching rate.

[0078] Comparative Example 2

[0079] This comparative example provides a method for leaching lepidolite and vanadium shale, which differs from the method in Example 1 in that it does not include a mechanical activation process, but instead involves direct mixing, roasting, and then leaching with sulfuric acid.

[0080] Compared to Example 1, the amount of sulfuric acid used in Comparative Example 1 increased by 35%.

[0081] Analysis showed that in Comparative Example 2, the leaching rate of Li was 82.62% and the leaching rate of V was 85.33%.

[0082] When lepidolite and vanadium shale are not mechanically activated beforehand, the subsequent high-temperature roasting effect will be affected, and the leaching rate of vanadium and lithium will be low after leaching with the same low-concentration inorganic acid solution.

[0083] Comparative Example 3

[0084] This comparative example provides a method for leaching lepidolite and vanadium shale, which differs from the method in Example 1 in that the roasting temperature is 750°C.

[0085] Analysis and testing showed that in Comparative Example 3, the leaching rate of Li was 71.34% and the leaching rate of V was 75.66%.

[0086] When the roasting temperature is below 850℃, it is also impossible to completely break the crystal structure of lithium-containing minerals in lepidolite and vanadium-containing minerals in vanadium shale. After leaching with the same low-concentration inorganic acid solution, the leaching rates of vanadium and lithium are low.

[0087] Comparative Example 4

[0088] This comparative example provides a method for leaching lepidolite and vanadium shale, which differs from the method in Example 2 in that the vanadium shale has a lower calorific value, is a low-carbon vanadium shale, and has a carbon content of 1.5%.

[0089] Analysis and testing showed that in Comparative Example 4, the leaching rate of Li was 74.33% and the leaching rate of V was 76.29%.

[0090] When the vanadium shale is low-carbon and the carbon content is not controlled, the heat generated is insufficient to meet the process requirements, and the crystal structure of lithium-bearing minerals in lepidolite and vanadium-bearing minerals in vanadium shale cannot be completely broken. Therefore, the leaching rate of vanadium and lithium is low after leaching with the same low-concentration organic acid mixed solution.

[0091] Comparative Example 5

[0092] This comparative example provides a method for leaching lepidolite and vanadium shale, which differs from the method in Example 2 in that it does not include a mechanical activation process, but instead involves direct mixing and roasting followed by leaching with organic acids.

[0093] Compared to Example 2, the amount of organic acid used in Comparative Example 2 increased by 40%.

[0094] Analysis and testing showed that in Comparative Example 5, the leaching rate of Li was 77.44% and the leaching rate of V was 73.62%.

[0095] Without prior mechanical activation treatment of lepidolite and vanadium shale, the subsequent high-temperature roasting effect will be affected, resulting in a lower leaching rate of vanadium and lithium after leaching with the same low-concentration organic acid mixed solution.

[0096] Comparative Example 6

[0097] This comparative example provides a method for leaching lepidolite and vanadium shale, which differs from the method in Example 2 in that the roasting temperature is 750°C.

[0098] Analysis and testing showed that in Comparative Example 6, the leaching rate of Li was 62.36% and the leaching rate of V was 71.82%.

[0099] When the roasting temperature is below 850℃, it is also impossible to completely break the crystal structure of lithium-bearing minerals in lepidolite and vanadium-bearing minerals in vanadium shale. After leaching with the same low-concentration organic acid mixed solution, the leaching rates of vanadium and lithium are low.

[0100] Comparative Example 7

[0101] This comparative example provides a method for salt roasting and concentrated sulfuric acid leaching of lepidolite and vanadium shale. In the raw ore, lepidolite contains 2.5% Li2O, and vanadium shale contains 9% carbon and 1.5% V2O.

[0102] The two minerals were mixed in a 1:1 ratio and then appropriately crushed into granules (particle size ~250um). Add 12% sulfate additive (calcium sulfate and sodium sulfate 1:1) to the mixed ore, press into pellets of about 35mm, and calcine at 900℃ for 2 hours in a muffle furnace; Finally, after cooling and ball milling (particle size ~100um), it was leached with 98% concentrated sulfuric acid.

[0103] Analysis and testing showed that in Comparative Example 7, the leaching rate of Li was 84%, and the leaching rate of V was 79%. Furthermore, it was noted that: sulfide waste gas was generated during the roasting process; the acidic wastewater and residue generated after high-concentration sulfuric acid leaching required further treatment; and the equipment showed signs of corrosion after prolonged use.

[0104] In summary, this invention combines vanadium-containing minerals and lepidolite for synergistic leaching of vanadium and lithium. Mechanical activation initially disrupts the crystal structure of vanadium shale and vanadium mica. Controlling the carbon content ensures high and uniform heat distribution within the roasting system during subsequent high-temperature roasting. Based on the carbon-controlled and mechanically activated mixture, high-temperature synergistic roasting is performed directly without additives, further disrupting the crystal structure of vanadium shale and vanadium mica, thus facilitating subsequent vanadium and lithium leaching and increasing the leaching rate. Finally, the cooled roasted clinker is leached with a low-concentration inorganic or organic acid. This increases the vanadium and lithium leaching rate while producing low-acidity leaching residue, eliminating acidic waste and making it suitable for industrial applications. This invention features a simple process that overcomes several problems associated with existing salt-based and acid-based roasting methods.

[0105] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for co-extracting vanadium and lithium from vanadium shale and lithium mica, characterized in that, include: The lepidolite and vanadium shale were mechanically activated, and the carbon content of the vanadium shale was adjusted. The mechanically activated mixture is then co-calcined to obtain calcined clinker; The roasted calcined material is leached in an acidic solution to obtain leachate and leachate residue.

2. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 1, characterized in that, The carbon content of the vanadium shale is adjusted to ≥8%; When the carbon content of the vanadium shale is less than 8%, carbon is added to make the carbon content ≥ 8%, wherein the carbon is one or more of coke and anthracite.

3. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 1, characterized in that, After mechanical activation, the particle size of the material is less than 50 μm, preferably less than 25 μm.

4. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 1, characterized in that, In the mixture, the mass ratio of lepidolite to vanadium shale is 1:5-5:1, preferably 3:5-5:

3.

5. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 1, characterized in that, In the step of co-calcining the mechanically activated mixture... The roasting temperature is 850℃-950℃, preferably 870℃-900℃; The roasting time is 0.5-3 hours, preferably 1-2 hours.

6. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 1, characterized in that, In the step of leaching the roasted clinker in an acid solution, the concentration of the acid solution is not higher than 45%.

7. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 6, characterized in that, The acid solution is an inorganic acid or an organic acid; The concentration of the inorganic acid is 0.5%-45%, preferably 10%-35%. The concentration of the organic acid is 0.5%-25%, preferably 15%-20%.

8. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 7, characterized in that, The inorganic acid is selected from sulfuric acid and nitric acid; The organic acid is selected from one or more of citric acid, oxalic acid, acetic acid, and formic acid.

9. The method for synergistic leaching of vanadium and lithium from vanadium shale and lithium mica according to claim 1, characterized in that, In the step of leaching the roasted clinker in an acid solution, the liquid-to-solid ratio of the leaching system is 5:1-10:1.

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