Method for extracting vanadium from high-calcium vanadium-containing shale

Abstract

The invention relates to a method for extracting vanadium from high-calcium vanadium-containing shale. After vanadium-containing shale is subjected to ore grinding and size mixing, vanadium-containing concentrate and tailings are obtained through a reverse flotation technology, the vanadium-containing concentrate is conveyed to a spiral chute to be separated and classified into coarse-grain-size and fine-grain-size vanadium-containing concentrate, the coarse-grain-size vanadium-containing concentrate and an activating agent are mixed and then conveyed to a ball mill to be activated, and activated slurry is obtained; and mixing the activated slurry with the fine-fraction vanadium-containing concentrate to obtain mixed slurry, introducing the mixed slurry into a leaching process, and performing solid-liquid separation to obtain the shale vanadium extraction pickle liquor. The vanadium-containing shale is characterized in that the grade of V2O5 is 0.8%-1.1%, the grade of CaO is 6.0%-12.0%, and the grade of MgO is 3.0%-6.0%; the vanadium concentration of shale vanadium extraction pickle liquor is 1.4-2.7 g / L; the method has the characteristics of high vanadium leaching rate, low acid consumption and environmental friendliness.

Description

Technical Field

[0001] The invention relates to the field of vanadium extraction from shale, and in particular to a method for extracting vanadium from high-calcium vanadium-containing shale. Background Art

[0002] At present, it is generally believed that the CaO content in vanadium-containing raw materials is greater than 5%, that is, it belongs to high-calcium vanadium-containing raw materials. The main minerals of such vanadium-containing shale are dolomite, calcite, quartz, illite, and kaolin. Vanadium is mostly present in the form of trivalent in the muscovite mineral lattice, with a stable structure and vanadium is not easy to release. Therefore, it is difficult to directly extract vanadium from such vanadium-containing shale by acid leaching. At the same time, the content of acid-consuming substances such as dolomite and calcite in the ore is relatively high, resulting in a relatively large acid consumption in the leaching process and a large number of impurity ions. The continued use of the sodium roasting process will not only produce toxic and harmful gases, but also vanadium is easy to generate water-insoluble calcium vanadate, resulting in a low water leaching rate. Therefore, it is necessary to remove the acid-consuming substances in the vanadium shale and leaching after mechanical activation to obtain a higher leaching rate.

[0003] The patented technology of "A method for pre-enriching vanadium by flotation from high-calcium mica-type vanadium-containing stone coal" (CN201510287402.9) obtains vanadium concentrate through a beneficiation process of reverse flotation followed by positive flotation. It has the advantages of simple process flow, low vanadium grade in tailings, and less vanadium loss. However, after reverse flotation with anionic collectors under alkaline conditions, acid needs to be added again to adjust the pH of the ore pulp to acidic conditions, and positive flotation with cationic collectors is performed. There are problems such as unreasonable process flow, conflict of reagent system, and large consumption of acid and alkali. The patented technology of "A method for recovering vanadium by flotation of vanadium mica ore" (CN201010528375.7) realizes the separation of vanadium mica and gangue minerals through classification and positive flotation process. However, the technology directly discards the tailings of minerals above 200 mesh, which has the disadvantages of low vanadium recovery rate and large vanadium loss.

[0004] The patented technology of "a method for leaching vanadium from stone coal by activating and leaching at the same time" (CN109112324A) is to treat vanadium-containing stone coal with 20-40wt% sulfuric acid for 5-10 days, then mix it with an oxidant and sulfuric acid, add it to a mill for mechanical activation and leaching for 0.5-48h, and the vanadium leaching reaches 85.1-92.9%. This technology directly leaches vanadium through sulfuric acid activation + mechanical activation to obtain a higher vanadium leaching rate, but both activation stages require the addition of a large amount of sulfuric acid, resulting in high acid consumption. The patented technology of "a method for directly leaching vanadium from vanadium shale" (CN115572842B) uses a vibrating screen to classify vanadium shale, and then regrinds the minerals on the screen. Although it effectively reduces the acid consumption in the leaching process, this technology is difficult to reduce the calcium oxide content in the original ore. After classification and activation, there is still a problem of high leaching acid consumption. At the same time, the vibrating screen has the problem of increasing the weight of the upper part of the screen, reducing the vibration transmission force, and weakening the screening effect.

[0005] In summary, the existing vanadium extraction process from shale has problems such as low vanadium recovery rate, high acid consumption and environmental pollution for high-calcium vanadium-containing shale. Summary of the invention

[0006] In order to solve the above problems, the present invention aims to provide a method for extracting vanadium from high-calcium vanadium-containing shale. The method is simple, has low sulfuric acid consumption, has a good vanadium extraction effect on high-calcium difficult-to-treat vanadium-containing shale, has a high vanadium recovery rate, and avoids the problems of direct acid leaching and high consumption of sulfuric acid and calcium fluoride.

[0007] The technical solution of the present invention is as follows: A method for extracting vanadium from high-calcium vanadium-containing shale, the method comprising the following steps: Step 1: grinding the raw ore to obtain mixed slurry I, and introducing the reverse flotation process to obtain vanadium concentrate and tailings; Step 2: adding water to the vanadium concentrate obtained in step 1 to prepare a slurry, and conveying the vanadium concentrate to a spiral chute through a pump for sorting to obtain a coarse-grained vanadium-containing concentrate and a fine-grained vanadium-containing concentrate; Step 3: Mix the coarse-grained vanadium-containing concentrate and the activator to obtain a mixed material; then add water to the mixed material to adjust the slurry, and feed the mixed slurry into a ball mill for activation to obtain an activated slurry, and mix the activated slurry with the fine-grained vanadium-containing concentrate to obtain a mixed ore slurry II; Step 4: introducing the mixed slurry II into the leaching process, and obtaining shale vanadium extraction acid leaching solution and leaching residue after solid-liquid separation; Complete the extraction of vanadium from high-calcium vanadium-containing shale.

[0008] Preferably, in step 1, the V2O5 grade of the raw ore is 0.8% to 1.1%, the CaO grade is 6.0% to 12.0%, and the MgO grade is 3.0% to 6.0%; The vanadium concentrate has a V2O5 grade of 1.5% to 1.7% and a CaO grade of 3.0% to 4.5%; The mixed slurry I has a particle size of less than 0.074 mm, accounting for 70% to 75%, and a slurry concentration of 20% to 33%.

[0009] Preferably, in step one, the reverse flotation process in step one is decalcified magnesium reverse flotation, and the reverse flotation is a mineral processing process of one roughing selection, one fine selection, and one scavenging selection. The flotation agents added in the roughing selection and the order of addition are respectively: pH adjuster, inhibitor, collector; collector is added in the fine selection; inhibitor and collector are added in the scavenging selection.

[0010] Further preferably, in step 1, the pH adjuster is sodium carbonate, the inhibitor is water glass, and the collector is a fatty acid anion collector; The total amount of reverse flotation reagents added, equivalent to the dry weight of the original ore, is: pH adjuster 1000~3000g / t, inhibitor 800~1500g / t, collector 2000~3000g / t.

[0011] Preferably, in step 2, water is added to the vanadium concentrate obtained in step 1 to adjust the slurry to a concentration of 20% to 25%; The coarse-grained vanadium-containing shale -0.074 mm accounts for 40%, and the fine-grained vanadium-containing shale -0.074 mm accounts for 80%.

[0012] Preferably, the activating agent in step three is one or more of calcium fluoride, sodium fluoride and potassium fluoride.

[0013] Preferably, in step three, the coarse-grained vanadium-containing concentrate and the activator are mixed in a mass ratio of 1: (0.15-0.25) to obtain a mixed material; then water is added to the mixed material at a liquid-to-solid ratio of 0.4-0.6 L / kg, and the slurry is adjusted to obtain a mixed slurry, which is fed into a ball mill for activation for 6-15 minutes to obtain an activated slurry, and the activated slurry is mixed with the fine-grained vanadium-containing concentrate to form mixed ore slurry II.

[0014] Preferably, the vanadium concentration of the shale vanadium extraction acid leaching solution in step 4 is 1.4-2.7 g / L.

[0015] Preferably, in step 4, the leaching process has a leaching temperature of 90-98° C., a leaching liquid-solid ratio of 1.5-2.5 kg / L, an amount of sulfuric acid of 20wt%-40wt% of the dry weight of the leached mineral, and a stirring time of the slurry in the leaching tank of 15-24h.

[0016] Preferably, the outer diameter of the spiral chute is 350-450mm, the pitch-to-diameter ratio is 0.33-0.38, the pitch is 140-150mm, the lateral inclination angle is 7.5-9.5︒, and the number of spiral groove turns is 4-6 turns; further preferably, the outer diameter of the spiral chute is 400mm, the pitch-to-diameter ratio is 0.36, the pitch is 144mm, the lateral inclination angle is 8.5︒, and the number of spiral groove turns is 5 turns.

[0017] The beneficial effects of the present invention are as follows: The vanadium-containing raw material of the present invention belongs to high-calcium vanadium-containing shale, and vanadium is mainly found in muscovite and clay minerals. The acid consumption in the leaching process is reduced by discarding dolomite, calcite and other acid-consuming substances in the vanadium-containing shale before leaching by means of ore dressing. The V2O5 grade of the vanadium concentrate is 1.5 to 1.8 times higher than that of the original ore, the CaO grade is reduced by 60% to 75%, the vanadium recovery rate is greater than or equal to 90%, and the generated ore dressing wastewater can be directly reused in the ore dressing process, which will not cause the concentrate index to decrease, and the recycling of wastewater is realized. It has the characteristics of high vanadium recovery rate and environmental friendliness.

[0018] The present invention adopts the spiral chute gravity selection method to classify the vanadium concentrate, avoids the vibration caused by the accumulation of minerals on the vibrating screen, and mechanically activates the coarse-grained vanadium concentrate, avoids the fine-grained vanadium shale from being too fine due to the activation time process, and then agglomerates in the subsequent leaching process, which is not conducive to the leaching of vanadium. The chemical adsorption of the activator changes the surface activity of the vanadium shale during the mechanical activation process, significantly reduces the mica interface reaction energy barrier in the subsequent leaching process, and is conducive to the destructive effect of hydrogen ions on the mica structure in the subsequent leaching process. At the same time, the activator is activated together with the vanadium shale in advance, so that the mica produces more active sites under the action of mechanical force, which is conducive to the combination of fluorine ions and silicon aluminum to form chemical adsorption, and avoids the problems of hydrofluoric acid volatilization in the subsequent acid leaching process, which is environmentally friendly. It has been determined that the leaching rate of the vanadium concentrate after mechanical activation reaches more than 90%, the vanadium leaching rate is high, and the acid consumption is 350g sulfuric acid per kilogram of ore, compared with 710g sulfuric acid per kilogram of ore in direct acid leaching of the original ore, the acid consumption is reduced by 50%, and the acid consumption is low.

[0019] Therefore, the present invention has the characteristics of high total vanadium recovery rate, low acid consumption and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a process flow chart of extracting vanadium from high-calcium vanadium-containing shale according to the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0022] In the context of this specification, except for the contents explicitly described, any matters or items not mentioned directly use the technology known in the art. Moreover, any embodiment described in this patent can be freely combined with one or more other embodiments described in this patent, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed in this patent, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0023] The data points disclosed in this specification include not only the specific disclosed numerical points, but also the endpoints of each numerical range. Any combination of these data points should be regarded as the disclosed or recorded range of the present invention, regardless of whether these numerical points are disclosed one by one in this article.

[0024] The spiral chute used in the embodiments and comparative examples has an outer diameter of 400 mm, a pitch-to-diameter ratio of 0.36, a pitch of 144 mm, a lateral inclination angle of 8.5°, and 5 spiral groove turns.

[0025] Example 1 A method for extracting vanadium from high-calcium vanadium-containing shale. The steps of the method described in this embodiment are: Step 1, introducing a mixed slurry I with a particle size of less than 0.074 mm accounting for 70% and a slurry concentration of 28% into a reverse flotation process to obtain vanadium concentrate I and tailings, wherein the reverse flotation process is reverse flotation decalcification and magnesium reverse flotation, and the reverse flotation is a mineral processing process of one roughing, one concentrating and one scavenging, and the flotation reagents added in each roughing stage and the order of addition are respectively: pH adjuster sodium carbonate, inhibitor water glass, collector sodium oleate, and the total amount added relative to the dry basis weight of the coarse-grained minerals sorted in the chute is: pH adjuster 2500 g / t, inhibitor 800 g / t, collector 2000 g / t; Step 2: adding water to the vanadium concentrate I obtained in step 1 to adjust the slurry to a concentration of 20%, and pumping the vanadium concentrate to a spiral chute for separation to obtain a coarse-grained vanadium-containing concentrate and a fine-grained vanadium-containing concentrate; Step 3: The coarse-grained vanadium-containing concentrate and calcium fluoride are mixed in a mass ratio of 1:0.18 to obtain a mixed material; water is then added to the mixed material at a liquid-solid ratio of 0.4 L / kg to adjust the slurry to obtain a mixed slurry, which is fed into a ball mill for activation for 8 minutes to obtain an activated slurry, and the activated slurry is mixed with the fine-grained vanadium-containing concentrate to form a mixed ore slurry II; Step 4: adding sulfuric acid to the mixed slurry II obtained in step 4 according to 40wt% of the dry weight of the dry ore, stirring for 20 h at 95°C and a liquid-solid ratio of 1.5 kg / L, and separating the solid and liquid to obtain shale vanadium extraction acid leaching solution and leaching residue; In this embodiment, the V2O5 grade of the original ore is 1.0%, the CaO grade is 10.5%, the V2O5 grade of the vanadium concentrate is 1.5%, the CaO grade is 3.8%, the V2O5 recovery rate is 90.5%, the vanadium concentration of the shale vanadium acid leaching solution is 2.3 g / L, and the vanadium leaching rate is 94.5%.

[0026] Example 2 In order to achieve the above object, the technical solution adopted by the present invention is: Step 1, introducing a mixed slurry I with a particle size of less than 0.074 mm accounting for 75% and a slurry concentration of 33% into a reverse flotation process to obtain vanadium concentrate I and tailings, wherein the reverse flotation process is reverse flotation decalcification and magnesium reverse flotation, and the reverse flotation is a mineral processing process of one roughing, one concentrating and one scavenging, and the flotation reagents added in each roughing stage and the order of addition are respectively: pH adjuster sodium carbonate, inhibitor water glass, collector sodium oleate, and the total amount added relative to the dry basis weight of the coarse-grained minerals sorted in the chute is: pH adjuster 2500 g / t, inhibitor 800 g / t, collector 2000 g / t; Step 2: adding water to the vanadium concentrate I obtained in step 1 to adjust the slurry to a concentration of 20%, and pumping the vanadium concentrate to a spiral chute for separation to obtain a coarse-grained vanadium-containing concentrate and a fine-grained vanadium-containing concentrate; Step 3: The coarse-grained vanadium-containing concentrate and calcium fluoride are mixed at a mass ratio of 1:0.15 to obtain a mixed material; water is then added to the mixed material at a liquid-solid ratio of 0.4 L / kg to adjust the slurry to obtain a mixed slurry, which is fed into a ball mill for activation for 8 minutes to obtain an activated slurry, and the activated slurry is mixed with the fine-grained vanadium-containing concentrate to form a mixed ore slurry II; Step 4: adding sulfuric acid to the mixed slurry II obtained in step 4 according to 40wt% of the dry weight of the dry ore, stirring for 20 h at 95°C and a liquid-solid ratio of 1.5 kg / L, and separating the solid and liquid to obtain shale vanadium extraction acid leaching solution and leaching residue; In this embodiment, the V2O5 grade of the ore is 1.0%, the CaO grade is 10.5%, the V2O5 grade of the vanadium concentrate is 1.6%, the CaO grade is 3.2%, the V2O5 recovery rate is 90.1%, the vanadium concentration of the shale vanadium acid leaching solution is 1.9 g / L, and the vanadium leaching rate is 90.2%. Example 3 In order to achieve the above object, the technical solution adopted by the present invention is: Step 1, introducing a mixed pulp I with a particle size of less than 0.074 mm accounting for 72% and a pulp concentration of 30% into a reverse flotation process to obtain vanadium concentrate I and tailings, wherein the reverse flotation process is reverse flotation decalcification and magnesium reverse flotation, and the reverse flotation is a mineral processing process of one roughing, one concentrating and one scavenging, and the flotation reagents added in each roughing stage and the order of addition are respectively: pH adjuster sodium carbonate, inhibitor water glass, collector sodium oleate, and the total amount added relative to the dry basis weight of the coarse-grained minerals sorted in the chute is: pH adjuster 2500 g / t, inhibitor 800 g / t, collector 2000 g / t; Step 2: adding water to the vanadium concentrate I obtained in step 1 to adjust the slurry to a concentration of 20%, and pumping the vanadium concentrate to a spiral chute for separation to obtain a coarse-grained vanadium-containing concentrate and a fine-grained vanadium-containing concentrate; Step 3: The coarse-grained vanadium-containing concentrate and calcium fluoride are mixed at a mass ratio of 1:0.16 to obtain a mixed material; water is then added to the mixed material at a liquid-solid ratio of 0.4 L / kg to adjust the slurry, and the mixed slurry is fed into a ball mill for activation for 8 minutes to obtain an activated slurry, and the activated slurry is mixed with the fine-grained vanadium-containing concentrate to form a mixed ore slurry II; Step 4: adding sulfuric acid to the mixed slurry II obtained in step 4 according to 40wt% of the dry weight of the dry ore, stirring for 20 h at 95°C and a liquid-solid ratio of 1.5 kg / L, and separating the solid and liquid to obtain shale vanadium extraction acid leaching solution and leaching residue; In this embodiment, the V2O5 grade of the original ore is 1.01%, the CaO grade is 10.1%, the V2O5 grade of the vanadium concentrate is 1.6%, the CaO grade is 4.1%, the V2O5 recovery rate is 91.5%, the vanadium concentration of the shale vanadium acid leaching solution is 2.2 g / L, and the vanadium leaching rate is 93.6%.

[0027] Comparative Example 1 The other conditions are consistent with those in Example 1, except that no activator is added in step 3. In this comparative example, the vanadium concentration of the shale vanadium acid leaching solution is 1.6 g / L, and the vanadium leaching rate is only 73.8%.

[0028] Comparative Example 2 The other conditions are consistent with those in Example 1, except that: without flotation in step 1, vanadium is directly extracted by chute sorting-mechanical activation acid leaching. In this comparative example, the vanadium concentration of the shale vanadium extraction acid leaching solution is 1.4 g / L, and the vanadium leaching rate is only 62.6%.

[0029] Comparative Example 3 The other conditions are consistent with those in Example 1, except that: without activation in step 3, in step 3, the coarse-grained vanadium-containing concentrate and calcium fluoride are mixed at a mass ratio of 1:0.16 to obtain a mixed material; then water is added to the mixed material at a liquid-solid ratio of 0.4 L / kg, and the slurry is adjusted to obtain a mixed slurry and mixed with the fine-grained vanadium-containing concentrate to form mixed slurry 3. In this comparative example, the vanadium concentration of the shale vanadium acid leaching solution is 1.7 g / L, and the vanadium leaching rate is only 80.5%.

[0030] Comparative Example 4 The other conditions are the same as those in Example 1, except that the spiral chute in step 2 is not used for sorting.

[0031] Step 3: Mix the vanadium concentrate I and calcium fluoride obtained in step 1 at a mass ratio of 1:0.16 to obtain a mixed material; then add water to the mixed material at a liquid-solid ratio of 0.4 L / kg, adjust the slurry, and feed the mixed slurry into a ball mill for activation for 8 minutes to obtain an activated slurry. In this comparative example, the vanadium concentration of the shale vanadium acid leaching solution is 1.8g / L, and the vanadium leaching rate is only 83.7%. By comparing Example 3 with Comparative Examples 1-4, it can be seen that the acid-consuming substances in the ore can be effectively removed after flotation, and the coarse-grained mica structure is further destroyed by the spiral chute sorting-mechanical activation process to avoid over-grinding of the fine-grained mica. The addition of the activator enables the mica to produce more active sites under the action of mechanical force, which is beneficial to improving the leaching rate of vanadium in the leaching process.

[0032] Example 4 4-1: Based on Example 1, the activating agent in step 3 is potassium fluoride, and the rest is the same as Example 1.

[0033] 4-2: Based on Example 1, the activating agent in step 3 is sodium fluoride, and the rest is the same as Example 1.

[0034] 4-3: Based on Example 1, the activator in step 3 is sodium fluorosilicate, and the rest is the same as Example 1.

[0035] 4-4: Based on Example 1, the activating agent in step 3 is sodium chloride, and the rest is the same as Example 1.

[0036] Through the above test, the data of vanadium extraction acid leaching solution of shale is as follows: Table 1

[0037] Compared with other activators, fluoride not only has the advantages of high vanadium leaching rate and low price, but also after fluoride enters the leaching system as an activator, the calcium and sodium ions remaining in the leaching solution will not affect the subsequent vanadium precipitation process. Therefore, using fluoride as an activator in the mechanical activation process has a significant promoting effect on the improvement of vanadium leaching rate.

[0038] Example 5 5-1: Based on Example 1, the pH adjuster in step 1 is sodium hydroxide, and the rest is the same as Example 1.

[0039] 5-2: Based on Example 1, the inhibitor in step 1 is causticized starch, and the rest is the same as Example 1.

[0040] 5-3: Based on Example 1, the collector in step 1 is oleic acid, and the rest is the same as Example 1.

[0041] Through the above tests, vanadium concentrate and shale vanadium acid leaching solution were obtained, and the data are as follows: Table 2

[0042] Using sodium carbonate as pH adjuster, water glass as inhibitor, sodium oleate as collector, the calcium oxide removal rate is high. The vanadium pentoxide recovery rate of vanadium concentrate is high. Under the same leaching conditions, the vanadium leaching rate is increased by 1.2~1.5 times. Therefore, using sodium carbonate as a pH adjuster, water glass as an inhibitor, and sodium oleate as a collector to decalcify the original ore for reverse flotation has a better effect of removing calcium oxide.

[0043] The technical solution of the present invention is explained through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above specific embodiments to be implemented. Any improvements made by technicians in the relevant field based on the present invention, or equivalent replacement of the materials selected by the present invention, etc., fall within the scope of protection of the patent.

Claims

1. A method for extracting vanadium from high-calcium vanadium-containing shale, characterized in that: The method comprises the following steps: Step 1: grinding the raw ore to obtain mixed slurry I, and introducing the reverse flotation process to obtain vanadium concentrate and tailings; Step 2: adding water to the vanadium concentrate obtained in step 1 to prepare a slurry, and conveying the vanadium concentrate to a spiral chute through a pump for sorting to obtain a coarse-grained vanadium-containing concentrate and a fine-grained vanadium-containing concentrate; Step 3: Mix the coarse-grained vanadium-containing concentrate and the activator to obtain a mixed material; then add water to the mixed material to adjust the slurry, and feed the mixed slurry into a ball mill for activation to obtain an activated slurry, and mix the activated slurry with the fine-grained vanadium-containing concentrate to obtain a mixed ore slurry II; Step 4: introducing the mixed slurry II into the leaching process, and obtaining shale vanadium extraction acid leaching solution and leaching residue after solid-liquid separation; Complete the extraction of vanadium from high-calcium vanadium-containing shale.

2. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step 1, the grade of V2O5 in the raw ore is 0.8% to 1.1%, the grade of CaO is 6.0% to 12.0%, and the grade of MgO is 3.0% to 6.0%; The vanadium concentrate has a V2O5 grade of 1.5% to 1.7% and a CaO grade of 3.0% to 4.5%; The mixed slurry I has a particle size of less than 0.074 mm, accounting for 70% to 75%, and a slurry concentration of 20% to 33%.

3. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step 1, the reverse flotation process is decalcified magnesium reverse flotation, and the reverse flotation is a mineral processing process of one roughing selection, one fine selection, and one scavenging selection. The flotation agents added in the roughing selection and the order of addition are respectively: pH adjuster, inhibitor, collector; collector is added in the fine selection; inhibitor and collector are added in the scavenging selection.

4. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 3, characterized in that: In the step 1, the pH adjuster is sodium carbonate, the inhibitor is water glass, and the collector is a fatty acid anion collector; The total amount of reverse flotation reagents added, equivalent to the dry weight of the original ore, is: pH adjuster 1000~3000g / t, inhibitor 800~1500g / t, collector 2000~3000g / t.

5. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step 2, water is added to the vanadium concentrate obtained in the step 1 to adjust the slurry to a concentration of 20% to 25%; The coarse-grained vanadium-containing shale -0.074 mm accounts for 40%, and the fine-grained vanadium-containing shale -0.074 mm accounts for 80%.

6. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step 3, the activating agent is one or more of calcium fluoride, sodium fluoride and potassium fluoride.

7. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step three, the coarse-grained vanadium-containing concentrate and the activator are mixed in a mass ratio of 1: (0.15-0.25) to obtain a mixed material; then water is added to the mixed material at a liquid-to-solid ratio of 0.4-0.6 L / kg, and the slurry is adjusted to obtain a mixed slurry, which is fed into a ball mill for activation for 6-15 minutes to obtain an activated slurry, and the activated slurry is mixed with the fine-grained vanadium-containing concentrate to form mixed ore slurry II.

8. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step 4, the vanadium concentration of the shale vanadium extraction acid leaching solution is 1.4-2.7 g / L.

9. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: In the step 4, the leaching process, the leaching temperature is 90-98° C., the leaching liquid-to-solid ratio is 1.5-2.5 kg / L, the amount of sulfuric acid is 20wt%-40wt% of the dry weight of the leached mineral, and the slurry is stirred in the leaching tank for 15-24h.

10. The method for extracting vanadium from high-calcium vanadium-containing shale according to claim 1, characterized in that: The outer diameter of the spiral chute is 350-450mm, the pitch-to-diameter ratio is 0.33-0.38, the pitch is 140-150mm, the lateral inclination angle is 7.5-9.5︒, and the number of spiral groove turns is 4-6; preferably, the outer diameter of the spiral chute is 400mm, the pitch-to-diameter ratio is 0.36, the pitch is 144mm, the lateral inclination angle is 8.5︒, and the number of spiral groove turns is 5.

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