Method for efficiently leaching vanadium and silver from multi-metal vanadium shale

Abstract

The invention relates to a method for efficiently leaching vanadium and silver from multi-metal vanadium shale. According to the technical scheme, the method comprises the following steps: crushing the polymetallic vanadium shale, and grinding the polymetallic vanadium shale until the polymetallic vanadium shale with the particle size of less than 0.074 mm accounts for 55-75wt% to obtain vanadium-silver A sulfuric acid solution and the vanadium-silver ore powder are mixed according to the liquid-solid ratio of (1.5-3): 1 L / kg, and mixed ore pulp I is obtained; fluoride accounting for 4-8 wt% of the vanadium-silver ore powder is added into the mixed ore pulp I, first stirring is carried out under the conditions of 80-95 DEG C and 100-400 r / min, natural cooling is carried out to 70-80 DEG C, and mixed ore pulp II is obtained; and then an oxidizing agent accounting for 6-10 wt% of the vanadium-silver ore powder and a leaching agent accounting for 60-80 wt% of the vanadium-silver ore powder are added into the mixed ore pulp II, secondary stirring is carried out under the condition of 100-400 r / min, solid-liquid separation is carried out, and leaching liquid containing vanadium and silver is obtained. The method has the advantages of being short in technological process, easy to operate and environmentally friendly, and the leaching rate of vanadium and silver in the obtained leaching solution containing vanadium and silver is high.

Description

Technical Field

[0001] The invention belongs to the technical field of polymetallic vanadium shale leaching solution and relates to a method for efficiently leaching vanadium and silver from polymetallic vanadium shale. Background Art

[0002] Vanadium in polymetallic vanadium shale is mainly found in mica minerals, and the mica lattice needs to be destroyed to release it. Silver in polymetallic vanadium shale is mainly found in pyrite or limonite in the form of fine particles, and a small amount is wrapped by minerals such as dolomite and barite. Its physical phase is complex, and it is mainly dispersed in polymetallic vanadium shale in the form of silver sulfide. This type of resource belongs to high-calcium-magnesium mica-type vanadium shale, and its leaching process will inevitably consume a large amount of acid. In addition, the occurrence of silver is complex and dispersed, making it difficult to select, smelt and recover this type of mineral resources.

[0003] At present, there are many studies on vanadium extraction from vanadium shale, but there are few studies on the comprehensive recovery of vanadium and silver from polymetallic vanadium shale. With the increasing depletion of resources, in order to maximize the utilization of resources, people have begun to explore the development and utilization of such resources. The traditional silver leaching method is cyanidation, but because cyanide is a highly toxic reagent, it has developed in the direction of non-cyanidation in recent years. Therefore, the selection of a suitable non-cyanidation silver extraction process and the vanadium extraction process for coupling the recovery of vanadium and silver from polymetallic vanadium shale has been of concern to those skilled in the art.

[0004] Li Jie (Li Jie. Research on the comprehensive recovery of silver and vanadium from silver-vanadium ore beneficiation [J]. Nonferrous Metals (Smelting Part), 2012, (12): 42-46.) The vanadium and silver in vanadium-silver ore were recovered by reverse flotation decalcification - high temperature and high acid leaching of vanadium - cyanide leaching of leached slag. After reverse flotation decalcification, the vanadium was acid leached. When the amount of sulfuric acid was 48wt%, the amount of calcium fluoride was 3wt%, the liquid-solid ratio was 1.2L / kg, 95°C, and leaching for 24h, the leaching rate of vanadium could reach 81%, and the leaching slag was obtained by solid-liquid separation. The pH of the leaching slag was adjusted to 10.0-10.5 with lime. Under the conditions of room temperature, 4g / L sodium cyanide, and a liquid-solid ratio of 2:1L / kg, the leaching was carried out for 12h, and the leaching rate of silver could reach 85%. This method takes a long time to leach vanadium and silver, and the silver leaching rate is not high. A large amount of lime is needed to adjust the acidic slag to alkaline. The process is relatively long, and the sodium cyanide used is a highly toxic reagent and is not environmentally friendly.

[0005] The patented technology of "Method for comprehensive wet recovery of selenium, vanadium and silver from vanadium-silver-selenium polymetallic ore" (CN 103555962 B) is aimed at vanadium ore containing silver and selenium. The raw ore is ground to a particle size of less than 0.074 mm, accounting for more than 85wt%, and sulfuric acid with an initial concentration of 1 to 5 mol / L is added. An oxidant and fluorite are added. The leaching temperature is 50 to 95°C and the liquid-solid ratio is (8 to 2): 1L / kg. After leaching for 2 to 24 hours, it is filtered to obtain a leaching solution containing vanadium and selenium and a leaching residue containing silver. The obtained vanadium-containing solution is recovered by conventional processes, and the obtained silver-containing leaching residue is recovered by cyanidation process. This technology does not further describe the silver extraction process. The cyanidation leaching method still has the problems of long process and environmental unfriendliness.

[0006] Duan Dongping (Duan Dongping, Zhou E, Chen Siming, et al. Research on Hydroprocessing Technology of Polymetallic Silver Ore [J]. Nonferrous Metals (Smelting Part), 2012, (05): 33-36.) used the method of pressurization-ammonia leaching-cyanidation to extract polymetallic silver ore. Under the conditions of oxygen partial pressure of 0.2MPa, reaction time of 6h, temperature of 85℃, concentrate particle size of -0.043mm accounting for 90%, stirring rate ≥800r / min, and NH3 / CO2 molar ratio of 5:2, the cyanide leaching rate of silver can reach 99%. Although the silver leaching index of this method is high, it uses pressurization and ammonia leaching treatment steps, which is complicated and has a long process.

[0007] The patented technology of "Method for recovering silver from wet zinc smelting waste residue" (CN 104212976A) aims at recovering silver from zinc smelting slag. The waste residue is roasted at 600-700℃ for 0.5-2h, 49-98g / L sulfuric acid is added at a liquid-solid ratio of (3-7): 1L / kg, and the mixture is stirred at room temperature to 60℃ and filtered; 200-390g / L sodium chloride solution is added to the acid leaching residue at a liquid-solid ratio of (3-7): 1L / kg, and then 28wt% sodium chlorate or potassium chlorate of the acid leaching residue is added and stirred thoroughly; 5-35wt% sulfuric acid of the acid leaching residue is added dropwise within 20-40min, the temperature is raised to 70-95℃, the leaching reaction is carried out for 2-5h, and the silver leaching rate is more than 90%. Although the silver leaching rate of this method is relatively high, the method adopts roasting pretreatment, which is complicated to operate, has a long process, and is not environmentally friendly.

[0008] In summary, it is difficult to comprehensively recover vanadium and silver from polymetallic vanadium shale, and its leaching process has the problems of low silver leaching index, long process, complex operation and unfriendly environment. Summary of the invention

[0009] The present invention aims to overcome the defects of the prior art and aims to provide a method for efficiently leaching vanadium and silver from polymetallic vanadium shale with a short process flow, simple operation and environmental friendliness; the vanadium and silver-containing leaching solution obtained by the method has a high vanadium and silver leaching rate.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm accounting for 55-75 wt% to obtain vanadium-silver ore powder.

[0012] The sulfuric acid solution is mixed with the vanadium-silver ore powder at a liquid-to-solid ratio of (1.5-3): 1 L / kg to obtain a mixed ore slurry I.

[0013] Then, fluoride accounting for 4-8 wt% of the vanadium-silver ore powder is added to the mixed slurry I, and the mixture is stirred for the first time at 80-95° C. and 100-400 r / min, and the mixture is naturally cooled to 70-80° C. to obtain mixed slurry II.

[0014] Then, 6-10 wt% of an oxidant and 60-80 wt% of a leaching agent accounting for the vanadium-silver ore powder are added to the mixed slurry II, and a second stirring is performed at 100-400 r / min to separate the solid and liquid to obtain a vanadium and silver-containing leaching solution.

[0015] In the polymetallic vanadium shale, the vanadium grade is 0.56-0.95 wt %; the silver grade is 50-120 g / t; the calcium grade is 2.10-5.90 wt %; and the magnesium grade is 1.50-2.80 wt %.

[0016] The sulfuric acid concentration of the sulfuric acid solution is 200-366 g / L.

[0017] The oxidant is one of sodium chlorate, potassium chlorate, sodium hypochlorite and potassium hypochlorite.

[0018] The leaching agent is one of sodium chloride, calcium chloride and potassium chloride.

[0019] The fluoride is one of calcium fluoride, sodium fluoride, potassium fluoride and ammonium fluoride.

[0020] The first stirring time is 4 to 12 hours.

[0021] The second stirring time is 4 to 8 hours.

[0022] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art:

[0023] 1. The prior art uses sulfuric acid to extract vanadium, and then uses lime to adjust the pH of the leached residue to alkaline before cyanidation to extract silver. The present invention can achieve the simultaneous extraction of vanadium and silver from polymetallic vanadium shale, overcoming the problem that the acidic leached residue needs to be adjusted to alkaline pH before silver leaching after conventional sulfuric acid vanadium extraction. Silver sulfide needs to be at high potential to be converted to Ag +The silver leaching system is formed by adding an oxidant of the same type as sodium chlorate and a leaching agent of the same type as sodium chloride. The acidic environment formed by leaching vanadium is used to ensure that the oxidant is or ClO - Excess Cl - Guaranteed Ag + AgCl x (x-1)- (x=2,3,4) effectively exists in the solution. Compared with the cyanidation method, the oxidation method has a more significant destruction on the structure of silver sulfide and is more beneficial to the subsequent complexation. The present invention can realize the simultaneous leaching of vanadium and silver without adjusting the pH to alkalinity, which greatly reduces the process flow. The leaching rate of vanadium is more than 80%, and the leaching rate of silver is as high as more than 90%. Therefore, the present invention has excellent leaching index and short process flow.

[0024] 2. In order to ensure the silver leaching index, the prior art uses pressurization or roasting for pretreatment; the silver in the polymetallic vanadium shale used in the present invention is mainly present in pyrite in the form of silver sulfide, and a small amount is present in minerals such as dolomite. Thermodynamic calculations show that the standard Gibbs free energy of the reaction between sulfuric acid and silver sulfide is greater than 0, and the reaction will not occur spontaneously. Therefore, sulfuric acid is used to extract vanadium first. This process can partially expose the silver minerals in pyrite and dolomite, which is beneficial for subsequent silver leaching. After reaching the optimal temperature for silver leaching by natural cooling, the oxidizing gas generated during the oxidation process remains in the ore pulp, and the strong oxidation reaction has a significant damage to the structure of silver sulfide. The leaching of vanadium and silver in the present invention is carried out in the same container. The leaching of vanadium has a certain pretreatment effect on the subsequent silver leaching, and there is no need to use complex means such as pressurization or roasting to treat the silver minerals separately, so the present invention is simple to operate.

[0025] 3. The existing technology mostly uses cyanidation method to extract silver or roasting pretreatment. The reagents used in the present invention are all non-toxic reagents. After fluoride destroys muscovite and releases vanadium, F - With Al 3+ form Complex ions in the form of or ClO - With H + The ClO2 or Cl2 generated by the reaction reacts with silver sulfide and reacts with the Cl in the leaching agent. - Together with Ag + The complex is formed in the solution, so the reaction products of the whole process are retained in the solution. The present invention avoids the risk of human poisoning caused by the volatilization of cyanide in the traditional cyanidation process, and is a full wet process, which avoids the generation of harmful gases such as SO2 during the roasting process to affect the environment, so the present invention is environmentally friendly.

[0026] Therefore, the present invention has the characteristics of short process flow, simple operation and environmental friendliness, and the obtained vanadium- and silver-containing leaching solution has high vanadium and silver leaching rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an Eh-pH diagram drawn by the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific implementation methods, which does not limit the scope of protection thereof.

[0029] A method for efficiently leaching vanadium and silver from polymetallic vanadium shale. The specific steps of the method described in this embodiment are:

[0030] The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm accounting for 55-75 wt% to obtain vanadium-silver ore powder.

[0031] The sulfuric acid solution is mixed with the vanadium-silver ore powder at a liquid-to-solid ratio of (1.5-3): 1 L / kg to obtain a mixed ore slurry I.

[0032] Then, fluoride accounting for 4-8 wt% of the vanadium-silver ore powder is added to the mixed slurry I, and the mixture is stirred for the first time at 80-95° C. and 100-400 r / min, and the mixture is naturally cooled to 70-80° C. to obtain mixed slurry II.

[0033] Then, 6-10 wt% of an oxidant and 60-80 wt% of a leaching agent accounting for the vanadium-silver ore powder are added to the mixed slurry II, and a second stirring is performed at 100-400 r / min to separate the solid and liquid to obtain a vanadium and silver-containing leaching solution.

[0034] In the polymetallic vanadium shale, the vanadium grade is 0.56-0.95 wt %; the silver grade is 50-120 g / t; the calcium grade is 2.10-5.90 wt %; and the magnesium grade is 1.50-2.80 wt %.

[0035] The sulfuric acid concentration of the sulfuric acid solution is 200-366 g / L.

[0036] The oxidant is one of sodium chlorate, potassium chlorate, sodium hypochlorite and potassium hypochlorite.

[0037] The leaching agent is one of sodium chloride, calcium chloride and potassium chloride.

[0038] The fluoride is one of calcium fluoride, sodium fluoride, potassium fluoride and ammonium fluoride.

[0039] The first stirring time is 4 to 12 hours.

[0040] The second stirring time is 4 to 8 hours.

[0041] Example 1

[0042] A method for efficiently leaching vanadium and silver from polymetallic vanadium shale. The specific steps of the method described in this embodiment are:

[0043] The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm accounting for 55 wt %, thereby obtaining vanadium-silver ore powder.

[0044] The sulfuric acid solution was mixed with the vanadium-silver ore powder at a liquid-to-solid ratio of 3:1 L / kg to obtain a mixed ore slurry I.

[0045] Then, fluoride accounting for 8 wt% of the vanadium-silver ore powder is added to the mixed slurry I, and the mixture is stirred for the first time at 95° C. and 400 r / min, and the mixture is naturally cooled to 75° C. to obtain mixed slurry II.

[0046] Then, 10 wt% of the oxidant and 80 wt% of the leaching agent of the vanadium-silver ore powder are added to the mixed slurry II, and a second stirring is performed at 400 r / min to separate the solid and liquid to obtain a vanadium- and silver-containing leaching solution.

[0047] In the polymetallic vanadium shale, the vanadium grade is 0.95wt%; the silver grade is 120g / t; the calcium grade is 5.90wt%; and the magnesium grade is 2.80wt%.

[0048] The sulfuric acid concentration of the sulfuric acid solution is 200 g / L.

[0049] The oxidant is sodium chlorate.

[0050] The leaching agent is sodium chloride.

[0051] The fluoride is calcium fluoride.

[0052] The first stirring time is 12 hours.

[0053] The second stirring time is 8 hours.

[0054] In the leaching solution containing vanadium and silver obtained from the polymetallic vanadium shale in this embodiment, the leaching rate of vanadium is 82.5%; and the leaching rate of silver is 92.1%.

[0055] Example 2

[0056] A method for efficiently leaching vanadium and silver from polymetallic vanadium shale. The specific steps of the method described in this embodiment are:

[0057] The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm accounting for 60wt% to obtain vanadium-silver ore powder.

[0058] The sulfuric acid solution was mixed with the vanadium-silver ore powder at a liquid-to-solid ratio of 2:1 L / kg to obtain a mixed ore slurry I.

[0059] Then, fluoride accounting for 4 wt% of the vanadium-silver ore powder is added to the mixed slurry I, and the mixture is stirred for the first time at 90° C. and 300 r / min, and the mixture is naturally cooled to 80° C. to obtain mixed slurry II.

[0060] Then, 6 wt% of the oxidant and 60 wt% of the leaching agent of the vanadium-silver ore powder are added to the mixed slurry II, and a second stirring is performed at 300 r / min to separate the solid and liquid to obtain a vanadium- and silver-containing leaching solution.

[0061] In the polymetallic vanadium shale, the vanadium grade is 0.65wt%; the silver grade is 70g / t; the calcium grade is 3.42wt%; and the magnesium grade is 1.84wt%.

[0062] The sulfuric acid concentration of the sulfuric acid solution is 325 g / L.

[0063] The oxidant is potassium chlorate.

[0064] The leaching agent is calcium chloride.

[0065] The fluoride is sodium fluoride.

[0066] The first stirring time is 8 hours.

[0067] The second stirring time is 4 hours.

[0068] In the leaching solution containing vanadium and silver obtained from the polymetallic vanadium shale in this embodiment, the leaching rate of vanadium is 80.2%; and the leaching rate of silver is 90.1%.

[0069] Example 3

[0070] A method for efficiently leaching vanadium and silver from polymetallic vanadium shale. The specific steps of the method described in this embodiment are:

[0071] The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm accounting for 65wt% to obtain vanadium-silver ore powder.

[0072] The sulfuric acid solution was mixed with the vanadium-silver ore powder at a liquid-to-solid ratio of 2.5:1 L / kg to obtain a mixed ore slurry I.

[0073] Then, fluoride accounting for 5 wt% of the vanadium-silver ore powder is added to the mixed slurry I, and the mixture is stirred for the first time at 85° C. and 200 r / min, and the mixture is naturally cooled to 72° C. to obtain mixed slurry II.

[0074] Then, 7 wt% of the oxidant and 70 wt% of the leaching agent of the vanadium-silver ore powder are added to the mixed slurry II, and a second stirring is performed at 200 r / min to separate the solid and liquid to obtain a vanadium- and silver-containing leaching solution.

[0075] In the polymetallic vanadium shale, the vanadium grade is 0.84wt%; the silver grade is 110g / t; the calcium grade is 4.86wt%; and the magnesium grade is 2.60wt%.

[0076] The sulfuric acid concentration of the sulfuric acid solution is 200 g / L.

[0077] The oxidant is sodium hypochlorite.

[0078] The leaching agent is potassium chloride.

[0079] The fluoride is potassium fluoride.

[0080] The first stirring time is 6 hours.

[0081] The second stirring time is 5h.

[0082] In the leaching solution containing vanadium and silver obtained from the polymetallic vanadium shale in this embodiment, the leaching rate of vanadium is 79.4%; and the leaching rate of silver is 89.4%.

[0083] Example 4

[0084] A method for efficiently leaching vanadium and silver from polymetallic vanadium shale. The specific steps of the method described in this embodiment are:

[0085] The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm accounting for 75 wt % to obtain vanadium-silver ore powder.

[0086] The sulfuric acid solution was mixed with the vanadium-silver ore powder at a liquid-to-solid ratio of 1.5:1 L / kg to obtain a mixed ore slurry I.

[0087] Then, fluoride accounting for 6 wt% of the vanadium-silver ore powder is added to the mixed slurry I, and the mixture is stirred for the first time at 80° C. and 100 r / min, and the mixture is naturally cooled to 70° C. to obtain mixed slurry II.

[0088] Then, 8 wt% of the oxidant and 80 wt% of the leaching agent of the vanadium-silver ore powder are added to the mixed slurry II, and stirred for the second time at 100 r / min to separate the solid and liquid to obtain a vanadium- and silver-containing leaching solution.

[0089] In the polymetallic vanadium shale, the vanadium grade is 0.56wt%; the silver grade is 50g / t; the calcium grade is 2.10wt%; and the magnesium grade is 1.50wt%.

[0090] The sulfuric acid concentration of the sulfuric acid solution is 366 g / L.

[0091] The oxidant is potassium hypochlorite.

[0092] The leaching agent is sodium chloride.

[0093] The fluoride is ammonium fluoride.

[0094] The first stirring time is 4 hours.

[0095] The second stirring time is 6 hours.

[0096] In the leaching solution containing vanadium and silver obtained from the polymetallic vanadium shale in this embodiment, the leaching rate of vanadium is 78.1%; and the leaching rate of silver is 91.5%.

[0097] Compared with the prior art, this specific implementation has the following positive effects:

[0098] 1. The prior art uses sulfuric acid to extract vanadium, and then uses lime to adjust the pH of the leached residue to alkaline before cyanidation to extract silver. This specific implementation method realizes the simultaneous extraction of vanadium and silver in multi-metallic vanadium shale, overcoming the problem that the acidic leached residue after conventional sulfuric acid extraction of vanadium needs to adjust the pH to alkaline before leaching silver. Figure 1 It is an Eh-pH diagram drawn in this specific embodiment; Figure 1 The Eh-pH diagram of this embodiment is drawn under the conditions of 75°C, 0.0001 mol / L silver concentration and 1 mol / L sulfur concentration, which is used to predict the existence form of silver sulfide under different potentials and pH conditions. Figure 1 It can be seen that under this condition, silver sulfide can only be converted into Ag when the potential is greater than 0.47V. + By adding an oxidant of the same type as sodium chlorate and a leaching agent of the same type as sodium chloride to form a silver leaching system, the acidic environment formed by vanadium leaching is used to ensure that the oxidant is or ClO - To play an oxidizing role, thus ensuring a high potential environment for the slurry. To avoid the formation of AgCl precipitation, add excess Cl- to ensure Ag + AgCl x (x-1)- (x=2,3,4) exists in the solution. Compared with the cyanidation method, the oxidation method has a more significant damage to the structure of silver sulfide and is more beneficial to the subsequent complexation. This specific implementation method realizes the simultaneous leaching of vanadium and silver without adjusting the pH to alkaline, which greatly reduces the process flow. The leaching rate of vanadium is more than 80%, and the leaching rate of silver is as high as more than 90%. Therefore, this specific implementation method has excellent leaching indicators and a short process flow.

[0099] 2. In order to ensure the silver leaching index, the prior art uses pressurization or roasting to perform pretreatment; the silver in the polymetallic vanadium shale used in this specific embodiment is mainly present in pyrite in the form of silver sulfide, and a small amount is present in minerals such as dolomite. Thermodynamic calculations show that the standard Gibbs free energy of the reaction between sulfuric acid and silver sulfide is greater than 0, and the reaction will not occur spontaneously. Therefore, sulfuric acid is used to extract vanadium first. This process can partially expose the silver minerals in pyrite and dolomite, which is beneficial for subsequent silver leaching. After reaching the optimal temperature for silver leaching through natural cooling, the oxidizing gas generated during the oxidation process remains in the ore pulp, and the strong oxidation reaction has a more significant damage to the structure of silver sulfide. In this specific embodiment, the leaching of vanadium and silver is carried out in the same container. The leaching of vanadium has a certain pretreatment effect on the subsequent silver leaching, and there is no need to use complex means such as pressurization or roasting to treat the silver minerals separately, so this specific embodiment is simple to operate.

[0100] 3. The existing technology mostly uses cyanidation method to extract silver or roasting pretreatment. The reagents used in this specific implementation are all non-toxic reagents. After fluoride destroys muscovite and releases vanadium, F - With Al 3+ form Complex ions in the form of or ClO - With H + The ClO2 or Cl2 generated by the reaction reacts with silver sulfide and reacts with the Cl in the leaching agent. - Together with Ag + The complex is in the solution, so the reaction products of the whole process are retained in the solution. This specific implementation avoids the risk of cyanide volatilization and poisoning in the traditional cyanidation process, and is a full wet process, which avoids the generation of harmful gases such as SO2 during the roasting process to affect the environment, so this specific implementation is environmentally friendly.

[0101] Therefore, the specific implementation method has the characteristics of short process flow, simple operation and environmental friendliness, and the obtained vanadium and silver-containing leaching solution has high vanadium and silver leaching rates.

Claims

1. A method for efficiently leaching vanadium and silver from polymetallic vanadium shale, characterized in that The method is: The polymetallic vanadium shale is crushed and ground to a particle size of less than 0.074 mm, accounting for 55-75 wt%, to obtain vanadium-silver ore powder; According to the liquid-solid ratio of (1.5-3): 1L / kg, a sulfuric acid solution is mixed with the vanadium-silver ore powder to obtain a mixed slurry I; then, a fluoride accounting for 4-8wt% of the vanadium-silver ore powder is added to the mixed slurry I, and a first stirring is performed at 80-95°C and 100-400r / min, and the mixture is naturally cooled to 70-80°C to obtain a mixed slurry II; then, an oxidant accounting for 6-10wt% of the vanadium-silver ore powder and a leaching agent accounting for 60-80wt% are added to the mixed slurry II, and a second stirring is performed at 100-400r / min, and the solid-liquid separation is performed to obtain a vanadium- and silver-containing leachate.

2. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that In the polymetallic vanadium shale, the vanadium grade is 0.56-0.95 wt %; the silver grade is 50-120 g / t; the calcium grade is 2.10-5.90 wt %; and the magnesium grade is 1.50-2.80 wt %.

3. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that The sulfuric acid concentration of the sulfuric acid solution is 200-366 g / L.

4. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that The oxidant is one of sodium chlorate, potassium chlorate, sodium hypochlorite and potassium hypochlorite.

5. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that The leaching agent is one of sodium chloride, calcium chloride and potassium chloride.

6. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that The fluoride is one of calcium fluoride, sodium fluoride, potassium fluoride and ammonium fluoride.

7. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that The first stirring time is 4 to 12 hours.

8. The method for efficiently leaching vanadium and silver from polymetallic vanadium shale according to claim 1, characterized in that The second stirring time is 4 to 8 hours.

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