Method for intensifying vanadium extraction through roasting and acid leaching of vanadium shale

Abstract

The invention relates to a method for intensifying vanadium extraction through roasting and acid leaching of vanadium shale. According to the scheme, the method comprises the following steps: crushing, roasting and grinding vanadium shale, and equally dividing to obtain n batches of roasted powder; adding water and concentrated sulfuric acid into the first batch of roasting powder, and then adding a first batch of leaching aid; and leaching, and carrying out solid-liquid separation to obtain a second batch of circulating leaching agent and a first batch of leaching liquid. A second batch of circulating leaching agent, concentrated sulfuric acid and water are added into the second batch of roasting powder to be mixed, and then a second batch of leaching assistant agent is added; and leaching, and carrying out solid-liquid separation to obtain a third batch of circulating leaching agent and a second batch of leaching liquid. ,...; the nth batch of circulating leaching agent and the (n-1) th batch of leaching agent are obtained, and n is a natural number ranging from 3 to 10. Mixing the n batches of lixiviates, adjusting the pH value, and adding sodium sulfite to obtain an extraction stock solution; and carrying out counter-current extraction and vanadium precipitation on the extraction stock solution to prepare vanadium pentoxide. The method is low in acid consumption, low in leaching aid consumption, high in vanadium leaching rate and good in vanadium and impurity separation effect.

Description

Technical Field

[0001] The invention belongs to the technical field of vanadium shale roasting and acid leaching, and specifically relates to a method for enhanced vanadium extraction by roasting and acid leaching of vanadium shale. Background Art

[0002] Vanadium shale is an important vanadium resource, but because vanadium mainly exists in the form of isomorphism in minerals, it is difficult to release the lattice. In order to improve the recovery rate, it is generally necessary to introduce high temperature, high acid and a large amount of leaching aids during the leaching process, which leads to problems such as difficulty in subsequent purification and separation.

[0003] The patented technology of "a method for extracting vanadium from vanadium-containing stone coal by decarburization-crystal breaking roasting" (CN 111304465B) is to suspend and roast stone coal powder at 700-900℃, then decarburize and roast at 500-800℃, then perform oxidation reaction at 750-900℃, and then extract vanadium by acid leaching with sulfuric acid solution. The process flow of the method is simple and the product properties are uniform, but the mass concentration of the sulfuric acid solution used is 25-35%, the acid consumption is large, and the vanadium leaching rate is only 80-90%, which is low.

[0004] The patented technology of "A method for comprehensive utilization of stone coal vanadium ore by oxidation and crystal breaking roasting" (CN 111719054B) is to subject stone coal powder ore to suspended roasting, decarbonization and oxidation, and then to acid aging leaching or direct leaching. The process of this method is simple and solves the problems of incomplete vanadium oxidation in traditional processes. However, the sulfuric acid consumption in the acid aging process of this method is 40-45%wt%, and the sulfuric acid consumption in the direct leaching process is 30-40wt%. The acid consumption is large, and the vanadium leaching rate in the direct leaching process is 75-80%, which is low.

[0005] The patented technology of "A method for extracting valuable elements from vanadium shale" (CN 115807172A) uses a two-stage leaching method to extract valuable elements from vanadium shale. The first stage uses hydrochloric acid leaching to remove impurities such as calcium in the vanadium shale, and the second stage uses a mixed acid of sulfuric acid and hydrochloric acid for leaching, which can extract vanadium, zinc and other elements from the vanadium shale. However, the amount of leaching aid added in this method is 2-6wt% of the original ore powder, which has the problem of large amount of leaching aid.

[0006] The patented technology of "A method for recovering vanadium from primary shale coal" (CN 117327930B) uses acidic substances such as sulfuric acid, hydrochloric acid, bromic acid, oxalic acid, sulfurous acid, phosphoric acid, etc. to alter the coal, and then leach it. This method does not require high-temperature, long-term oxidation roasting or sodiumization. However, this method requires the use of an oxidant to control the potential of the solution, and then a molybdenum-titanium extractant or resin is used to remove molybdenum and titanium to obtain a leaching solution after selective impurity removal. This method cannot directly separate vanadium and impurities from the source, and the vanadium-impurity separation effect is not good.

[0007] In summary, the existing vanadium shale extraction process has problems such as large amount of acid used in the leaching process, large amount of leaching aid consumption, low vanadium leaching rate and poor separation effect of vanadium and impurities. Summary of the invention

[0008] The present invention aims to overcome the defects of the prior art and aims to provide a method for vanadium shale roasting and acid leaching to enhance vanadium extraction, which has small acid dosage, small leaching agent consumption, high vanadium leaching rate and good separation effect of vanadium and impurities in the leaching process.

[0009] To achieve the above object, the steps of the technical solution adopted by the present invention are:

[0010] Step 1: Calcination

[0011] The crushed vanadium shale is roasted and ground to obtain roasted powder.

[0012] Step 2: Roasted powder is leached in batches

[0013] The roasted powder is divided into n equal parts, where n is a natural number of 3 to 10; and the powder is leached in order in n batches.

[0014] The first batch of roasted powder is mixed with water to obtain the first batch of mixed slurry.

[0015] Concentrated sulfuric acid is added to the first batch of mixed slurry and then the slurry is adjusted to obtain the first batch of leached slurry.

[0016] After adding the leaching aid to the first batch of leaching slurry and mixing the slurry, a leaching mixed slurry is obtained.

[0017] The leached slurry is stirred and leached at 80-100° C. for 4-10 hours, and then solid-liquid separation is performed to obtain a leached clear liquid and secondary leached residue. 40-60 vol% of the leached clear liquid is used as a circulating leaching agent for the next batch, and the remaining leached clear liquid is used as a finished leached liquid.

[0018] Starting from batch 2, follow these steps:

[0019] The roasted powder is mixed with the circulating leaching agent produced in the previous batch and then slurried to obtain a mixed slurry.

[0020] Concentrated sulfuric acid and the same volume of water as the finished leaching solution produced in the previous batch are added to the mixed slurry to obtain a leaching slurry.

[0021] A leaching aid is added to the secondary leaching slurry and then the slurry is adjusted to obtain a leaching mixed slurry.

[0022] The leached slurry is stirred and leached at 80-100° C. for 4-10 hours, and then solid-liquid separation is performed to obtain a leached clear liquid and secondary leached residue. 40-60 vol% of the leached clear liquid is used as a circulating leaching agent for the next batch, and the remaining leached clear liquid is used as a finished leached liquid.

[0023] In the nth batch, all the clear leaching liquid is used as the finished leaching liquid.

[0024] In the first batch of leaching, the mass ratio of concentrated sulfuric acid to roasted powder was 0.16-0.22:1; in the remaining batches, the mass ratio of concentrated sulfuric acid to roasted powder was 0.14-0.20:1.

[0025] In the first batch of leaching, the mass ratio of the calcined powder to the leaching aid is 1:0.02-0.05; in the remaining batches, the mass ratio of the calcined powder to the leaching aid is 1:0.015-0.04.

[0026] The leaching aid is a mixture of sodium nitrate or sodium nitrite and fluoride, the content of fluoride in the leaching aid is 70-90wt%, and the fluoride is one or more of calcium fluoride and sodium fluoride.

[0027] Step 3: Adjust the pH value of the leaching solution

[0028] All batches of finished product leachates are mixed, and the pH value is adjusted to 1.6-2.6 to obtain an adjusted leachate.

[0029] Sodium sulfite is added to the adjusted leaching solution, stirred, and filtered to obtain an extract solution and pH-adjusted residue.

[0030] Step 4: Solvent extraction and vanadium precipitation

[0031] The organic phase is mixed with the extraction stock solution, and subjected to countercurrent forward extraction at 10-30° C., and phases are separated to obtain a raffinate and a loaded organic phase.

[0032] The loaded organic phase is mixed with a stripping agent, and countercurrent stripping is performed at 10-30° C. to separate the phases to obtain a vanadium-rich solution and a lean organic phase.

[0033] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0034] Preferably, in step 3, the liquid-to-solid ratio of sodium sulfite added to the adjusted leachate is 1:(2-6) L / g; and the stirring is carried out at 60-80° C. and a rotation speed of 1-10 r / min for 30-60 min.

[0035] Preferably, in step 4, the volume ratio of the organic phase to the extraction solution is 1:(2-3), and the volume ratio of the loaded organic phase to the stripping agent is (4-10):1.

[0036] Preferably, the particle size of the crushed vanadium shale is ≤3 mm; the crushed vanadium shale has a V2O5 content of 0.5-1.5wt%, a CaO content of 1-6wt%, a SiO2 content of 50-90wt%, an Al2O3 content of 2-5wt%, and a Fe2O3 content of 1-4wt%;

[0037] The vanadium content of mica minerals in the crushed vanadium shale accounts for 40-95wt% of the total vanadium content.

[0038] Preferably, the calcination process is as follows: the calcination temperature is 400-700° C.; the calcination time is 30-90 min; and the particle size of the calcined powder is less than 0.074 mm, accounting for 20-50 wt%.

[0039] Preferably, the extractant is one or more of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0040] Preferably, the organic phase is a mixture of 15-25 vol% of an extractant, 5-10 vol% of secondary octanol and 65-80 vol% of sulfonated kerosene.

[0041] Preferably, the stripping agent is a 1-2 mol / L sulfuric acid solution.

[0042] Preferably, the lean organic phase is recycled as the organic phase in step 4 after being regenerated.

[0043] In this technical solution:

[0044] The chemical composition of each batch of leaching aid is the same;

[0045] The volume of each batch of leach slurry is equal;

[0046] Each batch of concentrated sulfuric acid has the same chemical composition, and the concentration of the concentrated sulfuric acid is greater than 98 wt %.

[0047] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0048] (1) The amount of acid used in the leaching process is small and the vanadium leaching rate is high. The present invention adds nitrate / nitrite as a leaching aid on the basis of the prior art adding fluoride as a leaching aid. The mechanism by which the present invention can significantly improve the vanadium leaching rate at a low acid dosage is:

[0049] ① Oxidation

[0050] Vanadium in vanadium shale is usually present in mica in the form of lattice substitution, generally in a low-valent state (such as +3 valence), with high stability and difficult to dissolve. During the leaching process, nitrate ions form nitric acid under acidic conditions, and nitric acid is adsorbed on the leaching reaction interface, which can oxidize the low-valent vanadium in vanadium shale mica into a high-valent state (such as +4, +5 valence). During the oxidation process, the mica lattice is distorted, the chemical activity of vanadium in the lattice is increased, and the binding force with the mica lattice is reduced, which is more conducive to the dissolution of vanadium under low-acid conditions.

[0051] ②Coordination effect

[0052] Nitrate ions can react with vanadium ions, aluminum ions and magnesium ions produced by the decomposition of vanadium-containing mica. During the sulfuric acid leaching process, nitrate ions act as ligands and combine with gradually dissolved vanadium ions, aluminum ions and magnesium ions to form relatively stable coordination compounds. This coordination balance drives the continuous dissolution of mica structural elements, prompting the continuous transfer of vanadium in vanadium-containing mica to the solution system, thereby improving the leaching effect of vanadium.

[0053] (2) Low consumption of leaching aid and high vanadium leaching rate. The present invention leaches the vanadium shale roasted powder in batches, and recycles part of the acid leaching solution of the previous batch as a circulating leaching aid to strengthen the leaching of the next batch of roasted powder. The mechanism of the present invention for improving the vanadium leaching rate at a low dosage of leaching aid is as follows: the circulating leaching agent contains hydrogen ions, sulfate, vanadium ions and other metal ions. Hydrogen ions and sulfate can replenish the acid consumed in the leaching reaction, maintain the acidity, and promote the dissolution of vanadium-containing minerals. In addition, as the number of cycles increases, the concentration of each metal ion in the leaching solution increases accordingly, and the ionic strength gradually increases, which enhances the destruction of vanadium-containing minerals and reduces the consumption of leaching aids in the leaching process.

[0054] (3) Good separation effect of vanadium and impurities. The present invention introduces strongly oxidizing nitrate ions into the roasted powder leaching system. Compared with the prior art, the mechanism of the present invention for achieving selective separation of vanadium and impurities is as follows: nitrate can selectively oxidize ferrous ions in the leachate, oxidizing divalent iron to trivalent iron. In the pH adjustment process, calcium hydroxide or calcium sulfate is generally selected as the pH adjuster. During the addition of calcium hydroxide or calcium sulfate, local overconcentration is prone to occur. When the local pH value in the leachate is too high, trivalent iron is easily co-precipitated with calcium sulfate into the pH adjustment slag, thereby achieving selective removal of iron ions in the leachate. According to measurements, the iron ion content in the original extraction solution can be reduced to below 600 mg / L, and the vanadium ion concentration is greater than 1.6 g / L, thereby achieving separation of vanadium and iron in the leachate.

[0055] Therefore, the present invention has the characteristics of small acid dosage in the leaching process, small leaching aid consumption, high vanadium leaching rate and good separation effect of vanadium and impurities. DETAILED DESCRIPTION

[0056] The present invention is further described below in conjunction with specific implementation modes, but is not intended to limit the protection scope thereof.

[0057] A method for vanadium shale roasting and acid leaching to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0058] Step 1: Calcination

[0059] The crushed vanadium shale is roasted and ground to obtain roasted powder.

[0060] Step 2: Roasted powder is leached in batches

[0061] The roasted powder is divided into n equal parts, where n is a natural number of 3 to 10; and the powder is leached in order in n batches.

[0062] The first batch of roasted powder is mixed with water to obtain the first batch of mixed slurry.

[0063] Concentrated sulfuric acid is added to the first batch of mixed slurry and then the slurry is adjusted to obtain the first batch of leached slurry.

[0064] After adding the leaching aid to the first batch of leaching slurry and mixing the slurry, a leaching mixed slurry is obtained.

[0065] The leached slurry is stirred and leached at 80-100° C. for 4-10 hours, and then solid-liquid separation is performed to obtain a leached clear liquid and secondary leached residue. 40-60 vol% of the leached clear liquid is used as a circulating leaching agent for the next batch, and the remaining leached clear liquid is used as a finished leached liquid.

[0066] Starting from batch 2, follow these steps:

[0067] The roasted powder is mixed with the circulating leaching agent produced in the previous batch and then slurried to obtain a mixed slurry.

[0068] Concentrated sulfuric acid and the same volume of water as the finished leaching solution produced in the previous batch are added to the mixed slurry to obtain a leaching slurry.

[0069] A leaching aid is added to the secondary leaching slurry and then the slurry is adjusted to obtain a leaching mixed slurry.

[0070] The leached slurry is stirred and leached at 80-100° C. for 4-10 hours, and then solid-liquid separation is performed to obtain a leached clear liquid and secondary leached residue. 40-60 vol% of the leached clear liquid is used as a circulating leaching agent for the next batch, and the remaining leached clear liquid is used as a finished leached liquid.

[0071] In the nth batch, all the clear leaching liquid is used as the finished leaching liquid.

[0072] In the first batch of leaching, the mass ratio of concentrated sulfuric acid to roasted powder was 0.16-0.22:1; in the remaining batches, the mass ratio of concentrated sulfuric acid to roasted powder was 0.14-0.20:1.

[0073] In the first batch of leaching, the mass ratio of the calcined powder to the leaching aid is 1:0.02-0.05; in the remaining batches, the mass ratio of the calcined powder to the leaching aid is 1:0.015-0.04.

[0074] The leaching aid is a mixture of sodium nitrate or sodium nitrite and fluoride, the content of fluoride in the leaching aid is 70-90wt%, and the fluoride is one or more of calcium fluoride and sodium fluoride.

[0075] Step 3: Adjust the pH value of the leaching solution

[0076] All batches of finished product leachates are mixed, and the pH value is adjusted to 1.6-2.6 to obtain an adjusted leachate.

[0077] Sodium sulfite is added to the adjusted leaching solution, stirred, and filtered to obtain an extract solution and pH-adjusted residue.

[0078] Step 4: Solvent extraction and vanadium precipitation

[0079] The organic phase is mixed with the extraction stock solution, and subjected to countercurrent forward extraction at 10-30° C., and phases are separated to obtain a raffinate and a loaded organic phase.

[0080] The loaded organic phase is mixed with a stripping agent, and countercurrent stripping is performed at 10-30° C. to separate the phases to obtain a vanadium-rich solution and a lean organic phase.

[0081] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0082] Preferably, in step 3, the liquid-to-solid ratio of sodium sulfite added to the adjusted leachate is 1:(2-6) L / g; and the stirring is carried out at 60-80° C. and a rotation speed of 1-10 r / min for 30-60 min.

[0083] Preferably, in step 4, the volume ratio of the organic phase to the extraction solution is 1:(2-3), and the volume ratio of the loaded organic phase to the stripping agent is (4-10):1.

[0084] Preferably, the particle size of the crushed vanadium shale is ≤3 mm; the crushed vanadium shale has a V2O5 content of 0.5-1.5wt%, a CaO content of 1-6wt%, a SiO2 content of 50-90wt%, an Al2O3 content of 2-5wt%, and a Fe2O3 content of 1-4wt%;

[0085] The vanadium content of mica minerals in the crushed vanadium shale accounts for 40-95wt% of the total vanadium content.

[0086] Preferably, the calcination process is as follows: the calcination temperature is 400-700° C.; the calcination time is 30-90 min; and the particle size of the calcined powder is less than 0.074 mm, accounting for 20-50 wt%.

[0087] Preferably, the extractant is one or more of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0088] Preferably, the organic phase is a mixture of 15-25 vol% of an extractant, 5-10 vol% of secondary octanol and 65-80 vol% of sulfonated kerosene.

[0089] Preferably, the stripping agent is a 1-2 mol / L sulfuric acid solution.

[0090] Preferably, the lean organic phase is recycled as the organic phase in step 4 after being regenerated.

[0091] In this specific implementation mode:

[0092] The chemical composition of each batch of leaching aid is the same;

[0093] The volume of each batch of leach slurry is equal;

[0094] Each batch of concentrated sulfuric acid has the same chemical composition;

[0095] The concentration of concentrated sulfuric acid is greater than 98wt%;

[0096] The lean organic phase is regenerated and recycled as an organic phase in step 4.

[0097] This will not be described in detail in the embodiments.

[0098] Example 1

[0099] A method for vanadium shale roasting and acid leaching to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0100] Step 1: Calcination

[0101] The crushed vanadium shale is roasted, and then the roasted vanadium shale is ground to obtain roasted powder.

[0102] Step 2: n batches of roasted powder leaching

[0103] The roasted powder was divided into three equal parts and leached in three batches in sequence.

[0104] Step 2.1: Leaching of the first batch of roasted powder

[0105] The first batch of calcined powder is mixed with water at a solid-liquid ratio of 1:0.8 Kg / L, and the slurry is adjusted to obtain the first batch of mixed slurry; the first batch of concentrated sulfuric acid is added to the first batch of mixed slurry at a mass ratio of the first batch of concentrated sulfuric acid: the first batch of calcined powder of 0.16:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0106] The first batch of leaching aid is added to the first batch of leaching slurry at a mass ratio of 1:0.02 of the first batch of calcined powder: the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0107] The first batch of leached slurry is stirred and leached at 80° C. for 4 hours, and the solid-liquid separation is performed for the first time to obtain the first batch of leached clear liquid and the first batch of leached residue; wherein: 40 vol% of the first batch of leached clear liquid is used as the second batch of circulating leaching agent, and the remainder of the first batch of leached clear liquid is used as the first batch of leaching liquid.

[0108] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0109] The first batch of leaching aids comprises 70 wt% of fluoride and 30 wt% of sodium nitrate; the fluoride is calcium fluoride.

[0110] Step 2.2: Leaching of the second batch of roasted powder

[0111] The second batch of roasted powder is mixed with the second batch of circulating leaching agent, and slurry is adjusted to obtain the second batch of mixed slurry; the second batch of concentrated sulfuric acid is added to the second batch of mixed slurry at a mass ratio of 0.14:1 of the second batch of concentrated sulfuric acid: the second batch of roasted powder, and water with the same volume as the first batch of leachate is added, and the slurry is adjusted to obtain the second batch of leaching slurry.

[0112] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of calcined powder to the second batch of leaching aid of 1:0.015 to obtain the second batch of leaching slurry.

[0113] The second batch of leached slurry is stirred and leached at 80° C. for 4 hours, and solid-liquid separation is performed for the second time to obtain the second batch of leached clear liquid and the second batch of leached residue; wherein: 40 vol% of the second batch of leached clear liquid is used as the third batch of circulating leaching agent, and the remainder of the second batch of leached clear liquid is used as the second batch of leaching liquid.

[0114] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0115] Step 2.3, leaching of the third batch of roasted powder

[0116] The third batch of roasted powder is mixed with the third batch of circulating leaching agent, and slurry is adjusted to obtain the third batch of mixed slurry; the third batch of concentrated sulfuric acid is added to the third batch of mixed slurry at a mass ratio of 0.14:1 between the third batch of concentrated sulfuric acid and the third batch of roasted powder, and water with the same volume as the second batch of leachate is added, and slurry is adjusted to obtain the third batch of leaching slurry.

[0117] The third batch of leaching aid is added to the third batch of leaching slurry at a mass ratio of the third batch of calcined powder to the third batch of leaching aid of 1:0.015 to obtain the third batch of leaching mixed slurry.

[0118] The third batch of leached slurry was stirred and leached at 80° C. for 4 hours, and solid-liquid separation was performed for the third time to obtain the third batch of leached clear liquid and the third batch of leached residue.

[0119] The clear liquid from the third batch of leaching is all the liquid from the third batch of leaching.

[0120] The third batch of leachate enters the pH adjustment process as the finished leachate.

[0121] Step 3: Adjust the pH value of the leaching solution

[0122] The first batch of leachate, the second batch of leachate and the third batch of leachate are mixed, and a pH adjuster is first added to the mixed leachate, wherein the pH adjuster is calcium hydroxide, and the pH value of the mixed leachate is adjusted to 1.6 to obtain an adjusted leachate; sodium sulfite is then added to the adjusted leachate at a liquid-to-solid ratio of 1:2 L / g; and then the mixture is stirred at 60° C. and a rotation speed of 1 r / min for 30 min, filtered, and an extractant and a pH-adjusted slag are obtained.

[0123] Step 4: Solvent extraction and vanadium precipitation

[0124] The organic phase and the extraction stock solution are mixed in a volume ratio of 1:2, and countercurrent forward extraction is performed at 10°C, and the phases are separated to obtain a raffinate and a loaded organic phase; the loaded organic phase and the stripping agent are mixed in a volume ratio of 4:1, and countercurrent stripping is performed at 10°C, and the phases are separated to obtain a vanadium-rich liquid and a lean organic phase.

[0125] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0126] The crushed vanadium shale has a V2O5 content of 0.5wt%, a CaO content of 1wt%, a SiO2 content of 50wt%, an Al2O3 content of 2wt% and a Fe2O3 content of 1wt%; the vanadium content of mica minerals in the crushed vanadium shale accounts for 40wt% of the total vanadium content.

[0127] The calcination process is as follows: the calcination temperature is 400° C. and the calcination time is 30 minutes.

[0128] The particle size of the calcined powder is less than 0.074 mm, accounting for 20 wt%.

[0129] The extractant is di(2-ethylhexyl)phosphonate.

[0130] The organic phase is a mixture of 15 vol% of an extractant, 5 vol% of secondary octanol and 80 vol% of sulfonated kerosene.

[0131] The stripping agent is 1 mol / L sulfuric acid solution.

[0132] Example 2

[0133] A method for vanadium shale roasting and acid leaching to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0134] Step 1: Calcination

[0135] The crushed vanadium shale is roasted, and then the roasted vanadium shale is ground to obtain roasted powder.

[0136] The roasted powder was divided into 4 equal parts and leached in 4 batches in sequence.

[0137] Step 2: n batches of roasted powder leaching

[0138] Step 2.1: Leaching of the first batch of roasted powder

[0139] The first batch of calcined powder is mixed with water at a solid-liquid ratio of 1:1.1 Kg / L, and the slurry is adjusted to obtain the first batch of mixed slurry; the first batch of concentrated sulfuric acid is added to the first batch of mixed slurry at a mass ratio of the first batch of concentrated sulfuric acid: the first batch of calcined powder of 0.17:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0140] The first batch of leaching aid is added to the first batch of leaching slurry at a mass ratio of 1:0.03 of the first batch of calcined powder to the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0141] The first batch of leached slurry is stirred and leached at 85° C. for 5 hours, and the solid-liquid separation is performed for the first time to obtain the first batch of leached clear liquid and the first batch of leached residue; wherein: 45 vol% of the first batch of leached clear liquid is used as the second batch of circulating leaching agent, and the remainder of the first batch of leached clear liquid is used as the first batch of leaching liquid.

[0142] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0143] The first batch of leaching aids comprises 75 wt % of fluoride and 25 wt % of sodium nitrite; the fluoride is sodium fluoride.

[0144] Step 2.2: Leaching of the second batch of roasted powder

[0145] The second batch of roasted powder is mixed with the second batch of circulating leaching agent, and slurry is adjusted to obtain the second batch of mixed slurry; the second batch of concentrated sulfuric acid is added to the second batch of mixed slurry at a mass ratio of 0.15:1 between the second batch of concentrated sulfuric acid and the second batch of roasted powder, and water with the same volume as that of the first batch of leachate is added, and slurry is adjusted to obtain the second batch of leaching slurry.

[0146] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of calcined powder to the second batch of leaching aid of 1:0.02 to obtain the second batch of leaching slurry.

[0147] The second batch of leached slurry is stirred and leached at 85° C. for 5 hours, and solid-liquid separation is performed for the second time to obtain the second batch of leached clear liquid and the second batch of leached residue; wherein: 45 vol% of the second batch of leached clear liquid is used as the third batch of circulating leaching agent, and the remainder of the second batch of leached clear liquid is used as the second batch of leaching liquid.

[0148] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0149] Step 2.3, leaching of the third batch of roasted powder

[0150] The third batch of roasted powder is mixed with the third batch of circulating leaching agent, and slurry is adjusted to obtain the third batch of mixed slurry; the third batch of concentrated sulfuric acid is added to the third batch of mixed slurry at a mass ratio of 0.15:1 between the third batch of concentrated sulfuric acid and the third batch of roasted powder, and water with the same volume as the second batch of leachate is added, and slurry is adjusted to obtain the third batch of leaching slurry.

[0151] The third batch of leaching aid is added to the third batch of leaching slurry at a mass ratio of the third batch of calcined powder to the third batch of leaching aid of 1:0.02 to obtain the third batch of leaching mixed slurry.

[0152] The third batch of leached slurry is stirred and leached at 85° C. for 5 hours, and the solid-liquid separation is performed for the third time to obtain the third batch of leached clear liquid and the third batch of leached residue; wherein: 45 vol% of the third batch of leached clear liquid is used as the fourth batch of circulating leaching agent, and the remainder of the third batch of leached clear liquid is used as the third batch of leaching liquid.

[0153] The third batch of leachate enters the pH adjustment process as the finished leachate.

[0154] Step 2.4, leaching of the fourth batch of roasted powder

[0155] The fourth batch of roasted powder is mixed with the fourth batch of circulating leaching agent, and slurry is adjusted to obtain the fourth batch of mixed slurry; the fourth batch of concentrated sulfuric acid is added to the fourth batch of mixed slurry at a mass ratio of 0.15:1 between the fourth batch of concentrated sulfuric acid and the fourth batch of roasted powder, and water with the same volume as the third batch of leachate is added, and slurry is adjusted to obtain the fourth batch of leaching slurry.

[0156] The fourth batch of leaching aid is added to the fourth batch of leaching slurry at a mass ratio of the fourth batch of calcined powder to the fourth batch of leaching aid of 1:0.02 to obtain the fourth batch of leaching mixed slurry.

[0157] The fourth batch of leached slurry was stirred and leached at 85° C. for 5 hours, and the solid-liquid separation was performed for the fourth time to obtain the fourth batch of leached clear liquid and the fourth batch of leached residue.

[0158] The clear liquid from the 4th batch of leaching is all the 4th batch of leaching liquid.

[0159] The fourth batch of leachate enters the pH adjustment process as the finished leachate.

[0160] Step 3: Adjust the pH value of the leaching solution

[0161] The first batch of leachate, the second batch of leachate, the third batch of leachate and the fourth batch of leachate are mixed, and a pH regulator is first added to the mixed leachate, wherein the pH regulator is calcium oxide, and the pH value of the mixed leachate is adjusted to 1.8 to obtain an adjusted leachate; sodium sulfite is then added to the adjusted leachate at a liquid-to-solid ratio of 1:3 L / g; and then the mixture is stirred at 65° C. and a rotation speed of 3 r / min for 40 min, filtered, and an extractant and a pH-adjusted slag are obtained.

[0162] Step 4: Solvent extraction and vanadium precipitation

[0163] The organic phase and the extraction stock solution are mixed at a volume ratio of 1:2.3, and countercurrent forward extraction is performed at 15°C, and the phases are separated to obtain a raffinate and a loaded organic phase; the loaded organic phase and the stripping agent are mixed at a volume ratio of 5:1, and countercurrent stripping is performed at 15°C, and the phases are separated to obtain a vanadium-rich liquid and a lean organic phase.

[0164] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0165] The crushed vanadium shale has a V2O5 content of 0.75wt%, a CaO content of 2wt%, a SiO2 content of 60wt%, an Al2O3 content of 3wt%, and a Fe2O3 content of 2wt%; the vanadium content of mica minerals in the crushed vanadium shale accounts for 60wt% of the total vanadium content.

[0166] The calcination process is as follows: the calcination temperature is 500° C. and the calcination time is 45 minutes.

[0167] The particle size of the calcined powder is less than 0.074 mm, accounting for 30 wt%.

[0168] The extractant is 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0169] The organic phase is a mixture of 17.5 vol% of an extractant, 7 vol% of secondary octanol and 75.5 vol% of sulfonated kerosene.

[0170] The stripping agent is a 1.25 mol / L sulfuric acid solution.

[0171] Example 3

[0172] A method for vanadium shale roasting and acid leaching to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0173] Step 1: Calcination

[0174] The crushed vanadium shale is roasted, and then the roasted vanadium shale is ground to obtain roasted powder.

[0175] Step 2: n batches of roasted powder leaching

[0176] The roasted powder was divided into 6 equal parts and leached in 6 batches in sequence.

[0177] Step 2.1: Leaching of the first batch of roasted powder

[0178] The first batch of calcined powder is mixed with water at a solid-liquid ratio of 1:1.4 Kg / L, and the slurry is adjusted to obtain the first batch of mixed slurry; the first batch of concentrated sulfuric acid is added to the first batch of mixed slurry at a mass ratio of the first batch of concentrated sulfuric acid: the first batch of calcined powder of 0.19:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0179] The first batch of leaching aid is added to the first batch of leaching slurry at a mass ratio of 1:0.035 of the first batch of calcined powder to the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0180] The first batch of leached slurry is stirred and leached at 90° C. for 7 hours, and the solid-liquid separation is performed for the first time to obtain the first batch of leached clear liquid and the first batch of leached residue; wherein: 50 vol% of the first batch of leached clear liquid is used as the second batch of circulating leaching agent, and the remainder of the first batch of leached clear liquid is used as the first batch of leaching liquid.

[0181] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0182] The first batch of leaching aids contains 80 wt% of fluoride and 20 wt% of sodium nitrate; the fluoride is a mixture of calcium fluoride and sodium fluoride.

[0183] Step 2.2: Leaching of the second batch of roasted powder

[0184] The second batch of roasted powder is mixed with the second batch of circulating leaching agent, and slurry is adjusted to obtain the second batch of mixed slurry; the second batch of concentrated sulfuric acid is added to the second batch of mixed slurry at a mass ratio of 0.17:1 between the second batch of concentrated sulfuric acid and the second batch of roasted powder, and water with the same volume as that of the first batch of leachate is added, and slurry is adjusted to obtain the second batch of leaching slurry.

[0185] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of calcined powder to the second batch of leaching aid of 1:0.03 to obtain the second batch of leaching mixed slurry.

[0186] The second batch of leached slurry is stirred and leached at 90° C. for 7 hours, and solid-liquid separation is performed for the second time to obtain the second batch of leached clear liquid and the second batch of leached residue; wherein: 50 vol% of the second batch of leached clear liquid is used as the third batch of circulating leaching agent, and the remainder of the second batch of leached clear liquid is used as the second batch of leaching liquid.

[0187] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0188] …….

[0190] The process of leaching the second batch of roasted powder described in step 2.2 is analogous to the process of leaching the fifth batch of roasted powder.

[0191] Step 2.5: Leaching of the fifth batch of roasted powder

[0192] The fifth batch of roasted powder is mixed with the fifth batch of circulating leaching agent, and slurry is adjusted to obtain the fifth batch of mixed slurry; the fifth batch of concentrated sulfuric acid is added to the fifth batch of mixed slurry at a mass ratio of 0.17:1 between the fifth batch of concentrated sulfuric acid and the fifth batch of roasted powder, and water with the same volume as the fourth batch of leachate is added, and slurry is adjusted to obtain the fifth batch of leaching slurry.

[0193] The fifth batch of leaching aid is added to the fifth batch of leaching slurry at a mass ratio of the fifth batch of calcined powder to the fifth batch of leaching aid of 1:0.03 to obtain the fifth batch of leaching mixed slurry.

[0194] The fifth batch of leached slurry is stirred and leached at 90° C. for 7 hours, and the solid-liquid separation is performed for the fifth time to obtain the fifth batch of leached clear liquid and the fifth batch of leached residue; wherein: 50 vol% of the fifth batch of leached clear liquid is used as the sixth batch of circulating leaching agent, and the remainder of the fifth batch of leached clear liquid is used as the fifth batch of leaching liquid.

[0195] The fifth batch of leachate enters the pH adjustment process as the finished leachate.

[0196] Step 2.6, leaching of the sixth batch of roasted powder

[0197] The sixth batch of roasted powder is mixed with the sixth batch of circulating leaching agent, and slurry is adjusted to obtain the sixth batch of mixed slurry; the sixth batch of concentrated sulfuric acid is added to the sixth batch of mixed slurry at a mass ratio of 0.17:1 between the sixth batch of concentrated sulfuric acid and the sixth batch of roasted powder, and water with the same volume as that of the fifth batch of leachate is added, and slurry is adjusted to obtain the sixth batch of leaching slurry.

[0198] The sixth batch of leaching aid is added to the sixth batch of leaching slurry at a mass ratio of the sixth batch of calcined powder to the sixth batch of leaching aid of 1:0.03 to obtain the sixth batch of leaching mixed slurry.

[0199] The sixth batch of leached slurry was stirred and leached at 90° C. for 7 hours, and the sixth batch of leached clear liquid and the sixth batch of leached residue were obtained by solid-liquid separation.

[0200] The clear liquid from the 6th batch of leaching is all the 6th batch of leaching liquid.

[0201] The sixth batch of leachate enters the pH adjustment process as the finished leachate.

[0202] Step 3: Adjust the pH value of the leaching solution

[0203] The first batch of leachate, the second batch of leachate, ..., the fifth batch of leachate and the sixth batch of leachate are mixed, and a pH regulator is first added to the mixed leachate, wherein the pH regulator is calcium hydroxide, and the pH value of the mixed leachate is adjusted to 2.0 to obtain an adjusted leachate; then, sodium sulfite is added to the adjusted leachate at a liquid-to-solid ratio of 1:4 L / g; then, the mixture is stirred at 70° C. and a rotation speed of 5 r / min for 45 min, and filtered to obtain an extract solution and a pH-adjusted slag.

[0204] Step 4: Solvent extraction and vanadium precipitation

[0205] The organic phase and the extraction stock solution are mixed at a volume ratio of 1:2.5, and countercurrent forward extraction is performed at 20°C, and the phases are separated to obtain a raffinate and a loaded organic phase; the loaded organic phase and the stripping agent are mixed at a volume ratio of 7:1, and countercurrent stripping is performed at 20°C, and the phases are separated to obtain a vanadium-rich liquid and a lean organic phase.

[0206] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0207] The crushed vanadium shale has a V2O5 content of 1wt%, a CaO content of 3wt%, a SiO2 content of 70wt%, an Al2O3 content of 3.5wt%, and a Fe2O3 content of 2.5wt%; the vanadium content of mica minerals in the crushed vanadium shale accounts for 70wt% of the total vanadium content.

[0208] The calcination process is as follows: the calcination temperature is 550° C. and the calcination time is 60 minutes.

[0209] The particle size of the calcined powder is less than 0.074 mm, accounting for 35 wt%.

[0210] The extractant is a mixture of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0211] The organic phase is a mixture of 20 vol% of an extractant, 7.5 vol% of secondary octanol and 72.5 vol% of sulfonated kerosene.

[0212] The stripping agent is a 1.5 mol / L sulfuric acid solution.

[0213] Example 4

[0214] A method for vanadium shale roasting and acid leaching to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0215] Step 1: Calcination

[0216] The crushed vanadium shale is roasted, and then the roasted vanadium shale is ground to obtain roasted powder.

[0217] Step 2: n batches of roasted powder leaching

[0218] The roasted powder was divided into 8 equal parts and leached in 8 batches in sequence.

[0219] Step 2.1: Leaching of the first batch of roasted powder

[0220] The first batch of calcined powder is mixed with water at a solid-liquid ratio of 1:1.7 kg / L, and the slurry is adjusted to obtain the first batch of mixed slurry; the first batch of concentrated sulfuric acid is added to the first batch of mixed slurry at a mass ratio of the first batch of concentrated sulfuric acid: the first batch of calcined powder of 0.21:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0221] The first batch of leaching aid is added to the first batch of leaching slurry at a mass ratio of 1:0.04 of the first batch of calcined powder: the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0222] The first batch of leached slurry is stirred and leached at 95° C. for 9 hours, and the solid-liquid separation is performed for the first time to obtain the first batch of leached clear liquid and the first batch of leached residue; wherein: 55 vol% of the first batch of leached clear liquid is used as the second batch of circulating leaching agent, and the remainder of the first batch of leached clear liquid is used as the first batch of leaching liquid.

[0223] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0224] The first batch of leaching aids contains 85 wt% of fluoride and 15 wt% of sodium nitrite; the fluoride is calcium fluoride.

[0225] Step 2.2: Leaching of the second batch of roasted powder

[0226] The second batch of roasted powder is mixed with the second batch of circulating leaching agent, and slurry is adjusted to obtain the second batch of mixed slurry; the second batch of concentrated sulfuric acid is added to the second batch of mixed slurry at a mass ratio of 0.19:1 between the second batch of concentrated sulfuric acid and the second batch of roasted powder, and water with the same volume as that of the first batch of leachate is added, and slurry is adjusted to obtain the second batch of leaching slurry.

[0227] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of calcined powder to the second batch of leaching aid of 1:0.035 to obtain the second batch of leaching mixed slurry.

[0228] The second batch of leached slurry is stirred and leached at 95° C. for 9 hours, and solid-liquid separation is performed for the second time to obtain the second batch of leached clear liquid and the second batch of leached residue; wherein: 55 vol% of the second batch of leached clear liquid is used as the third batch of circulating leaching agent, and the remainder of the second batch of leached clear liquid is used as the second batch of leaching liquid.

[0229] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0230] …….

[0232] The process of leaching the second batch of roasted powder described in step 2.2 is analogous to the process of leaching the seventh batch of roasted powder.

[0233] Step 2.7, leaching of the seventh batch of roasted powder

[0234] The 7th batch of calcined powder is mixed with the 7th batch of circulating leaching agent, and slurry is adjusted to obtain the 7th batch of mixed slurry; the 7th batch of concentrated sulfuric acid is added to the 7th batch of mixed slurry at a mass ratio of 0.19:1 between the 7th batch of concentrated sulfuric acid and the 7th batch of calcined powder, and water with the same volume as the 6th batch of leachate is added to adjust the slurry to obtain the 7th batch of leaching slurry.

[0235] The seventh batch of leaching aid was added to the seventh batch of leaching slurry at a mass ratio of the seventh batch of calcined powder to the seventh batch of leaching aid of 1:0.035 to obtain the seventh batch of leaching mixed slurry.

[0236] The 7th batch of leached slurry was stirred and leached at 95° C. for 9 hours, and the solid-liquid separation was performed for the 7th time to obtain the 7th batch of leached clear liquid and the 7th batch of leached residue; wherein: 55 vol% of the 7th batch of leached clear liquid was used as the 8th batch of circulating leaching agent, and the remainder of the 7th batch of leached clear liquid was used as the 7th batch of leaching liquid.

[0237] The seventh batch of leachate enters the pH adjustment process as the finished leachate.

[0238] Step 2.8, leaching of the eighth batch of roasted powder

[0239] The 8th batch of calcined powder is mixed with the 8th batch of circulating leaching agent, and slurry is adjusted to obtain the 8th batch of mixed slurry; the 8th batch of concentrated sulfuric acid is added to the 8th batch of mixed slurry at a mass ratio of 0.19:1 between the 8th batch of concentrated sulfuric acid and the 8th batch of calcined powder, and then water with the same volume as the 7th batch of leachate is added, and slurry is adjusted to obtain the 8th batch of leaching slurry.

[0240] The eighth batch of leaching aid was added to the eighth batch of leaching slurry at a mass ratio of the eighth batch of calcined powder to the eighth batch of leaching aid of 1:0.035 to obtain the eighth batch of leaching mixed slurry.

[0241] The eighth batch of leached slurry was stirred and leached at 95° C. for 9 hours, and the eighth batch of solid-liquid separation was performed to obtain the eighth batch of leached clear liquid and the eighth batch of leached residue.

[0242] The clear liquid from the 8th batch of leachate is all the 8th batch of leachate.

[0243] The 8th batch of leachate enters the pH adjustment process as the finished leachate.

[0244] Step 3: Adjust the pH value of the leaching solution

[0245] The first batch of leachate, the second batch of leachate, ..., the seventh batch of leachate and the eighth batch of leachate are mixed, and a pH regulator is first added to the mixed leachate, wherein the pH regulator is calcium oxide, and the pH value of the mixed leachate is adjusted to 2.3 to obtain an adjusted leachate; then, sodium sulfite is added to the adjusted leachate at a liquid-to-solid ratio of 1:5 L / g; then, the mixture is stirred at 75° C. and a rotation speed of 7 r / min for 50 min, and filtered to obtain an extract solution and a pH-adjusted slag.

[0246] Step 4: Solvent extraction and vanadium precipitation

[0247] The organic phase and the extraction stock solution are mixed at a volume ratio of 1:2.7, and countercurrent extraction is performed at 25°C, and the phases are separated to obtain a raffinate and a loaded organic phase; the loaded organic phase and the stripping agent are mixed at a volume ratio of 9:1, and countercurrent stripping is performed at 25°C, and the phases are separated to obtain a vanadium-rich liquid and a lean organic phase.

[0248] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0249] The crushed vanadium shale has a V2O5 content of 1.25wt%, a CaO content of 4wt%, a SiO2 content of 80wt%, an Al2O3 content of 4wt%, and a Fe2O3 content of 3wt%; the vanadium content of mica minerals in the crushed vanadium shale accounts for 80wt% of the total vanadium content.

[0250] The calcination process is as follows: the calcination temperature is 600° C. and the calcination time is 75 minutes.

[0251] The particle size of the calcined powder is less than 0.074 mm, accounting for 40 wt%.

[0252] The extractant is di(2-ethylhexyl)phosphonate.

[0253] The organic phase is a mixture of 22.5 vol% of an extractant, 8 vol% of secondary octanol and 69.5 vol% of sulfonated kerosene.

[0254] The stripping agent is a 1.75 mol / L sulfuric acid solution.

[0255] Example 5

[0256] A method for vanadium shale roasting and acid leaching to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0257] Step 1: Calcination

[0258] The crushed vanadium shale is roasted, and then the roasted vanadium shale is ground to obtain roasted powder.

[0259] Step 2: n batches of roasted powder leaching

[0260] The roasted powder was divided into 10 equal parts and leached in 10 batches in sequence.

[0261] Step 2.1: Leaching of the first batch of roasted powder

[0262] The first batch of calcined powder is mixed with water at a solid-liquid ratio of 1:2.0 Kg / L, and the slurry is adjusted to obtain the first batch of mixed slurry; the first batch of concentrated sulfuric acid is added to the first batch of mixed slurry at a mass ratio of the first batch of concentrated sulfuric acid: the first batch of calcined powder of 0.22:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0263] The first batch of leaching aid is added to the first batch of leaching slurry at a mass ratio of 1:0.05 of the first batch of calcined powder to the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0264] The first batch of leached slurry is stirred and leached at 100° C. for 10 hours, and the solid-liquid separation is performed for the first time to obtain the first batch of leached clear liquid and the first batch of leached residue; wherein: 60 vol% of the first batch of leached clear liquid is used as the second batch of circulating leaching agent, and the remainder of the first batch of leached clear liquid is used as the first batch of leaching liquid.

[0265] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0266] The first batch of leaching aids comprises 90 wt % of fluoride and 10 wt % of sodium nitrate; the fluoride is sodium fluoride.

[0267] Step 2.2: Leaching of the second batch of roasted powder

[0268] The second batch of roasted powder is mixed with the second batch of circulating leaching agent, and slurry is adjusted to obtain the second batch of mixed slurry; the second batch of concentrated sulfuric acid is added to the second batch of mixed slurry at a mass ratio of 0.20:1 between the second batch of concentrated sulfuric acid and the second batch of roasted powder, and water with the same volume as that of the first batch of leachate is added, and slurry is adjusted to obtain the second batch of leaching slurry.

[0269] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of calcined powder to the second batch of leaching aid of 1:0.04 to obtain the second batch of leaching slurry.

[0270] The second batch of leached slurry is stirred and leached at 100° C. for 10 hours, and solid-liquid separation is performed for the second time to obtain the second batch of leached clear liquid and the second batch of leached residue; wherein: 60 vol% of the second batch of leached clear liquid is used as the third batch of circulating leaching agent, and the remainder of the second batch of leached clear liquid is used as the second batch of leaching liquid.

[0271] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0272] …….

[0274] The process of leaching the second batch of roasted powder described in step 2.2 is analogous to the process of leaching the ninth batch of roasted powder.

[0275] Step 2.9, leaching of the ninth batch of roasted powder

[0276] The 9th batch of roasted powder is mixed with the 9th batch of circulating leaching agent, and slurry is adjusted to obtain the 9th batch of mixed slurry; the 9th batch of concentrated sulfuric acid is added to the 9th batch of mixed slurry at a mass ratio of 0.20:1 between the 9th batch of concentrated sulfuric acid and the 9th batch of roasted powder, and then water with the same volume as the 8th batch of leachate is added, and slurry is adjusted to obtain the 9th batch of leaching slurry.

[0277] The ninth batch of leaching aid was added to the ninth batch of leaching slurry at a mass ratio of the ninth batch of calcined powder to the ninth batch of leaching aid of 1:0.04 to obtain the ninth batch of leaching mixed slurry.

[0278] The 9th batch of leached slurry is stirred and leached at 100° C. for 10 hours, and the solid-liquid separation is performed for the 9th time to obtain the 9th batch of leached clear liquid and the 9th batch of leached residue; wherein: 60 vol% of the 9th batch of leached clear liquid is used as the 10th batch of circulating leaching agent, and the remainder of the 9th batch of leached clear liquid is used as the 9th batch of leaching liquid.

[0279] The 9th batch of leachate enters the pH adjustment process as the finished leachate.

[0280] Step 2.10, leaching of the 10th batch of roasted powder

[0281] The 10th batch of roasted powder is mixed with the 10th batch of circulating leaching agent, and slurry is adjusted to obtain the 10th batch of mixed slurry; the 10th batch of concentrated sulfuric acid is added to the 10th batch of mixed slurry at a mass ratio of 0.20:1 between the 10th batch of concentrated sulfuric acid and the 10th batch of roasted powder, and water with the same volume as the 9th batch of leachate is added, and slurry is adjusted to obtain the 10th batch of leaching slurry.

[0282] The tenth batch of leaching aid is added to the tenth batch of leaching slurry at a mass ratio of the tenth batch of calcined powder to the tenth batch of leaching aid of 1:0.04 to obtain the tenth batch of leaching mixed slurry.

[0283] The 10th batch of leached slurry was stirred and leached at 100° C. for 10 hours, and the solid-liquid separation was performed for the 10th time to obtain the 10th batch of leached clear liquid and the 10th batch of leached residue.

[0284] The 10th batch of leaching clear liquid is all the 10th batch of leaching liquid.

[0285] The 10th batch of leachate enters the pH adjustment process as the finished leachate.

[0286] Step 3: Adjust the pH value of the leaching solution

[0287] The first batch of leachate, the second batch of leachate, ..., the ninth batch of leachate and the tenth batch of leachate are mixed, and a pH regulator is first added to the mixed leachate, wherein the pH regulator is calcium hydroxide, and the pH value of the mixed leachate is adjusted to 2.6 to obtain an adjusted leachate; then, sodium sulfite is added to the adjusted leachate at a liquid-to-solid ratio of 1:6 L / g; and then, the mixture is stirred at 80° C. and a rotation speed of 10 r / min for 60 min, and filtered to obtain an extract solution and a pH-adjusted slag.

[0288] Step 4: Solvent extraction and vanadium precipitation

[0289] The organic phase and the extraction stock solution are mixed at a volume ratio of 1:3, and countercurrent forward extraction is performed at 30°C, and the phases are separated to obtain a raffinate and a loaded organic phase; the loaded organic phase and the stripping agent are mixed at a volume ratio of 10:1, and countercurrent stripping is performed at 30°C, and the phases are separated to obtain a vanadium-rich liquid and a lean organic phase.

[0290] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0291] The crushed vanadium shale has a V2O5 content of 1.5wt%, a CaO content of 6wt%, a SiO2 content of 90wt%, an Al2O3 content of 5wt%, and a Fe2O3 content of 4wt%; the vanadium content of mica minerals in the crushed vanadium shale accounts for 95wt% of the total vanadium content.

[0292] The calcination process is as follows: the calcination temperature is 700° C. and the calcination time is 90 minutes.

[0293] The particle size of the calcined powder is less than 0.074 mm, accounting for 50 wt%.

[0294] The extractant is 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0295] The organic phase is a mixture of 25 vol% of an extractant, 10 vol% of secondary octanol and 65 vol% of sulfonated kerosene.

[0296] The stripping agent is a 2 mol / L sulfuric acid solution.

[0297] Compared with the prior art, this specific implementation has the following beneficial effects:

[0298] (1) The amount of acid used in the leaching process is small and the vanadium leaching rate is high. In addition to adding fluoride as a leaching aid in the prior art, this specific embodiment also adds nitrate / nitrite as a leaching aid. The mechanism by which this specific embodiment can significantly improve the vanadium leaching rate at a low acid dosage is:

[0299] ① Oxidation

[0300] Vanadium in vanadium shale is usually present in mica in the form of lattice substitution, generally in a low-valent state (such as +3 valence), with high stability and difficult to dissolve. During the leaching process, nitrate ions form nitric acid under acidic conditions, and nitric acid is adsorbed on the leaching reaction interface, which can oxidize the low-valent vanadium in vanadium shale mica into a high-valent state (such as +4, +5 valence). During the oxidation process, the mica lattice is distorted, the chemical activity of vanadium in the lattice is increased, and the binding force with the mica lattice is reduced, which is more conducive to the dissolution of vanadium under low-acid conditions.

[0301] ②Coordination effect

[0302] Nitrate ions can react with vanadium ions, aluminum ions and magnesium ions produced by the decomposition of vanadium-containing mica. During the sulfuric acid leaching process, nitrate ions act as ligands and combine with gradually dissolved vanadium ions, aluminum ions and magnesium ions to form relatively stable coordination compounds. This coordination balance drives the continuous dissolution of mica structural elements, prompting the continuous transfer of vanadium in vanadium-containing mica to the solution system, thereby improving the leaching effect of vanadium.

[0303] (2) Low consumption of leaching aid and high vanadium leaching rate. This specific embodiment leaches the vanadium shale roasted powder in batches, and recycles part of the acid leaching solution of the previous batch as a circulating leaching aid to strengthen the leaching of the next batch of roasted powder. The mechanism of this specific embodiment to improve the vanadium leaching rate at a low dosage of leaching aid is: the circulating leaching agent contains hydrogen ions, sulfate, vanadium ions and other metal ions. Hydrogen ions and sulfates can replenish the acid consumed in the leaching reaction, maintain acidity, and promote the dissolution of vanadium-containing minerals. In addition, as the number of cycles increases, the concentration of each metal ion in the leachate increases accordingly, and the ionic strength gradually increases, which enhances the destruction of vanadium-containing minerals and reduces the consumption of leaching aids in the leaching process.

[0304] (3) Good separation effect of vanadium and impurities. This specific embodiment introduces strongly oxidizing nitrate ions into the roasting powder leaching system. Compared with the prior art, the mechanism of selective separation of vanadium and impurities in this specific embodiment is: nitrate can selectively oxidize ferrous ions in the leachate, oxidizing divalent iron to trivalent iron. In the pH adjustment process, calcium hydroxide or calcium sulfate is generally selected as the pH adjuster. During the addition of calcium hydroxide or calcium sulfate, local overconcentration is prone to occur. When the local pH value in the leachate is too high, trivalent iron is easy to co-precipitate with calcium sulfate into the pH adjustment slag, thereby achieving selective removal of iron ions in the leachate. It has been determined that the iron ion content in the original extraction solution can be reduced to below 600 mg / L, and the vanadium ion concentration is greater than 1.6 g / L, thereby achieving the separation of vanadium and iron in the leachate.

[0305] Therefore, the present specific implementation has the characteristics of small amount of acid used in the leaching process, small amount of leaching aid consumption, high vanadium leaching rate and good separation effect of vanadium and impurities.

Claims

1. A method for intensified vanadium extraction by roasting and acid leaching of vanadium shale, characterized in that: The following steps are involved: Step 1: Calcination The crushed vanadium shale is roasted and ground to obtain roasted powder; Step 2: Roasted powder is leached in batches Divide the roasted powder into n equal parts, where n is a natural number of 3 to 10; and perform leaching in order in n batches; Mixing the first batch of roasted powder with water to obtain the first batch of mixed slurry; Add concentrated sulfuric acid to the first batch of mixed pulp and adjust the pulp to obtain the first batch of leached pulp; Adding a leaching aid to the first batch of leached slurry and then mixing the slurry to obtain a leached mixed slurry; Stirring the leached slurry at 80-100° C. for 4-10 hours, then performing solid-liquid separation to obtain a leached clear liquid and secondary leached residue, using 40-60 vol% of the leached clear liquid as a circulating leaching agent for the next batch, and the remaining leached clear liquid as a finished leached liquid; Starting from batch 2, follow these steps: The roasted powder is mixed with the circulating leaching agent produced in the previous batch and then slurried to obtain a mixed slurry; Adding concentrated sulfuric acid and the same volume of water as the finished leachate produced in the previous batch to the mixed slurry to obtain a leach slurry; Adding a leaching aid to the secondary leaching slurry and then mixing the slurry to obtain a leaching mixed slurry; Stirring the leached slurry at 80-100° C. for 4-10 hours, then performing solid-liquid separation to obtain a leached clear liquid and secondary leached residue, using 40-60 vol% of the leached clear liquid as a circulating leaching agent for the next batch, and the remaining leached clear liquid as a finished leached liquid; In the nth batch, all the leaching clear liquid is used as the finished product leachate; In the first batch of leaching, the mass ratio of concentrated sulfuric acid to roasted powder is 0.16-0.22:1; in the remaining batches, the mass ratio of concentrated sulfuric acid to roasted powder is 0.14-0.20:1; In the first batch of leaching, the mass ratio of the calcined powder to the leaching aid is 1:0.02-0.05; in the remaining batches, the mass ratio of the calcined powder to the leaching aid is 1:0.015-0.04; The leaching aid is a mixture of sodium nitrate or sodium nitrite and fluoride, the content of fluoride in the leaching aid is 70-90wt%, and the fluoride is one or more of calcium fluoride and sodium fluoride; Step 3: Adjust the pH value of the leaching solution Mix all batches of finished product leachate, adjust the pH value to 1.6-2.6, and obtain an adjusted leachate; Adding sodium sulfite to the adjusted leachate, stirring, and filtering to obtain an extract solution and a pH-adjusted residue; Step 4: Solvent extraction and vanadium precipitation The organic phase is mixed with the extraction stock solution, and subjected to countercurrent forward extraction at 10-30° C., and phase separation is performed to obtain a raffinate and a loaded organic phase; The loaded organic phase is mixed with a stripping agent, and countercurrent stripping is performed at 10-30° C. to separate the phases to obtain a vanadium-rich solution and a lean organic phase; The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

2. The method for enhanced vanadium extraction by roasting and acid leaching of vanadium shale according to claim 1, characterized in that: In step 3, sodium sulfite is added to the adjusted leachate at a liquid-to-solid ratio of 1:(2-6) L / g; stirring is performed at 60-80° C. and a rotation speed of 1-10 r / min for 30-60 min.

3. The method for vanadium shale roasting and acid leaching intensified vanadium extraction according to claim 1, characterized in that: In step 4, the volume ratio of the organic phase to the extraction solution is 1:(2-3), and the volume ratio of the loaded organic phase to the stripping agent is (4-10):

1.

4. The method for vanadium shale roasting and acid leaching intensified vanadium extraction according to claim 1, characterized in that: The crushed vanadium shale has a particle size of ≤3 mm; the crushed vanadium shale has a V2O5 content of 0.5-1.5 wt%, a CaO content of 1-6 wt%, a SiO2 content of 50-90 wt%, an Al2O3 content of 2-5 wt%, and a Fe2O3 content of 1-4 wt%; The vanadium content of mica minerals in the crushed vanadium shale accounts for 40-95wt% of the total vanadium content.

5. The method for enhanced vanadium extraction by roasting and acid leaching of vanadium shale according to claim 1, characterized in that: The calcination process is as follows: the calcination temperature is 400-700° C.; the calcination time is 30-90 min; the particle size of the calcined powder is less than 0.074 mm, accounting for 20-50 wt %.

6. The method for vanadium shale roasting and acid leaching intensified vanadium extraction according to claim 1, characterized in that: The extractant is one or more of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

7. The method for enhanced vanadium extraction by roasting and acid leaching of vanadium shale according to claim 1, characterized in that: The organic phase is a mixture of 15-25 vol% of an extractant, 5-10 vol% of secondary octanol and 65-80 vol% of sulfonated kerosene.

8. The method for enhanced vanadium extraction by roasting and acid leaching of vanadium shale according to claim 1, characterized in that: The stripping agent is a 1-2 mol / L sulfuric acid solution.

9. The method for enhanced vanadium extraction by roasting and acid leaching of vanadium shale according to claim 1, characterized in that: The lean organic phase is regenerated and recycled as an organic phase in step 4.