Method for intensifying vanadium extraction through direct acid leaching of vanadium shale

Abstract

The invention relates to a method for intensifying vanadium extraction through direct acid leaching of vanadium shale. According to the scheme, the method comprises the following steps: crushing and levigating vanadium shale, and equally dividing to obtain n batches of raw ore powder; adding water and concentrated sulfuric acid into the first batch of raw ore 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 a second batch of raw ore powder to be mixed, and then a second batch of leaching aid 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 environment-friendly.

Description

Technical Field

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

[0002] Extracting vanadium pentoxide from vanadium shale is an important way to obtain vanadium. Since vanadium is mainly present in the mica lattice in the form of lattice substitution, the extraction process has problems such as difficulty in dissolving vanadium in a low-acid environment and co-dissolving vanadium and impurities in a high-acid environment, resulting in difficulty in subsequent separation. Direct acid leaching process and roasting acid leaching process are the two main methods for vanadium extraction. In order to destroy the lattice structure of vanadium, it is usually necessary to roast or add a large amount of sulfuric acid and leaching agents to enhance leaching during the vanadium extraction process.

[0003] The patented technology of "A method for leaching vanadium from stone coal vanadium ore" (CN 110029235B) uses a sulfuric acid leaching process to extract vanadium from stone coal. The leaching rate of vanadium in the stone coal vanadium ore is improved by subjecting the stone coal vanadium ore to sulfuric acid aging treatment and then hydrothermal leaching. The vanadium leaching rate can reach more than 93%, and no leaching aid is required, which is environmentally friendly. However, the method uses a high consumption of concentrated sulfuric acid of up to 80wt%, which is a large acid consumption.

[0004] The patented technology of "a method for wet extraction of vanadium from stone coal" (CN 108642306B) uses concentrated sulfuric acid to leach stone coal, leaching vanadium and associated metal elements in stages, using concentrated sulfuric acid to destroy the stone coal structure, deeply leaching a variety of impurity metals, and then using dilute sulfuric acid and additives to leach low-valent vanadium to obtain a relatively pure vanadium-containing leachate, avoiding the problem of impurities and vanadium entering the acid leaching solution together in the traditional acid leaching method. This process has a high vanadium leaching rate, a high leaching rate with associated metal elements, and a thorough separation, but the consumption of concentrated sulfuric acid used is as high as 60wt%, and the acid consumption is large.

[0005] The patented technology of "A method for extracting vanadium from high-calcium stone coal" (CN 109136551B) is to wet-grind stone coal ore and directly mix it with concentrated sulfuric acid to leach vanadium, and obtain a leachate for preparing V2O5 products. Although this method has better overcome the problems of complicated process, high cost and environmental pollution in the existing concentrated sulfuric acid aging vanadium extraction technology, the consumption of concentrated sulfuric acid in this method is 38-45wt%, and the acid consumption is large.

[0006] The patented technology of "A method for selectively leaching and separating vanadium and iron from stone coal vanadium ore" (CN 110066920B) uses a two-stage leaching process to selectively leach iron and vanadium. First, dilute sulfuric acid is used to mainly leach iron and other impurity elements, and then concentrated sulfuric acid is used for aging treatment to destroy the mineral structure of aluminum silicate in the stone coal vanadium ore and promote the leaching of vanadium. Although it prevents iron and other impurity elements in the stone coal vanadium ore from entering the vanadium-containing solution in large quantities from the source, the leaching rate of vanadium in this process is low.

[0007] The patented technology of "A method for extracting valuable elements from vanadium shale" (CN115807172A) crushes and grinds vanadium shale to obtain raw ore powder, and then uses hydrochloric acid solution as a leaching agent to leach the raw ore powder through primary hydrochloric acid to obtain primary leaching liquid and primary leaching residue. The primary leaching residue is subjected to secondary leaching using a mixed acid of sulfuric acid and hydrochloric acid as a secondary leaching agent to obtain secondary leaching liquid and secondary leaching residue. After adjusting the pH value of the secondary leaching liquid, vanadium is first extracted with a phosphonic acid extractant, and then zinc is extracted with an amine extractant. After the secondary leaching residue is decarbonized, silicon-rich slag is obtained. Although this process realizes the extraction of multiple valuable elements, the amount of leaching aid added is 2 to 6wt% of the raw ore powder, and the consumption of leaching aid is large.

[0008] The patented technology of "A method for extracting vanadium pentoxide from stone coal" (CN 119020614A) is that after stone coal ore is crushed and ground, an acid, a complexing agent and water are added for mixed leaching. After leaching, a pore-forming agent is added for medium-temperature calcination. After roasting, sulfuric acid solution is added for leaching again. Then, the leaching liquid is purified and enriched by an ion exchange process. After vanadium precipitation, vanadium pentoxide is obtained. Although this method can achieve a higher vanadium leaching rate while reducing acid consumption, it requires roasting the ore, which produces harmful gases and is easy to pollute the environment.

[0009] 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 easy environmental pollution. Summary of the invention

[0010] The present invention aims to overcome the defects of the prior art and aims to provide a method for direct acid leaching of vanadium shale to enhance vanadium extraction, which has small acid consumption, small leaching aid consumption, high vanadium leaching rate and is environmentally friendly.

[0011] To achieve the above object, the steps of the technical solution adopted by the present invention are:

[0012] Step 1: Ore crushing and grinding

[0013] The vanadium shale is crushed and ground to obtain raw ore powder.

[0014] Step 2: Batch leaching of raw ore powder

[0015] The raw ore powder is divided into n equal parts, where n is a natural number of 3 to 10, and leached in n batches in sequence.

[0016] The first batch of raw ore powder is mixed with water to obtain the first batch of mixed slurry.

[0017] Concentrated sulfuric acid is added to the first batch of mixed slurry and then slurried to obtain the first batch of leached slurry.

[0018] After adding the leaching aid to the first batch of leaching slurry and mixing the slurry, a leaching mixed slurry is obtained.

[0019] 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.

[0020] Starting from batch 2, follow these steps:

[0021] The raw ore powder is mixed with the circulating leaching agent produced in the previous batch and then slurried to obtain a mixed slurry.

[0022] 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.

[0023] A leaching aid is added to the secondary leaching slurry and then the slurry is adjusted to obtain a leaching mixed slurry.

[0024] 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.

[0025] In the nth batch, all the clear leaching liquid is used as the finished leaching liquid.

[0026] During the first batch of leaching, the mass ratio of concentrated sulfuric acid to raw ore powder was 0.20-0.25:1; for the remaining batches, the mass ratio of concentrated sulfuric acid to raw ore powder was 0.18-0.22:1.

[0027] In the first batch of leaching, the mass ratio of the raw ore powder to the leaching aid is 1:0.02-0.05; in the remaining batches, the mass ratio of the raw ore powder to the leaching aid is 1:0.015-0.04.

[0028] 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.

[0029] Step 3: Adjust the pH value of the leaching solution

[0030] All batches of finished product leachates are mixed, and the pH value is adjusted to 1.6-2.6 to obtain an adjusted leachate.

[0031] Sodium sulfite is added to the adjusted leaching solution, stirred, and filtered to obtain an extract solution and pH-adjusted residue.

[0032] Step 4: Solvent extraction and vanadium precipitation

[0033] 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.

[0034] 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.

[0035] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0036] 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.

[0037] 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.

[0038] Preferably, the 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%;

[0039] The vanadium content of mica minerals in vanadium shale accounts for 40 to 95 wt% of the total vanadium content.

[0040] Preferably, the particle size of the raw ore powder is less than 0.074 mm and accounts for 20 to 50 wt%.

[0041] Preferably, the extractant is one or more of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0042] 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.

[0043] Preferably, the stripping agent is a 1-2 mol / L sulfuric acid solution.

[0044] Preferably, the lean organic phase is recycled as the organic phase in step 4 after being regenerated.

[0045] In this technical solution:

[0046] The chemical composition of each batch of leaching aid is the same;

[0047] The volume of each batch of leach slurry is equal;

[0048] Each batch of concentrated sulfuric acid has the same chemical composition, and the concentration of the concentrated sulfuric acid is greater than 98 wt %.

[0049] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0050] (1) Small amount of acid used in the leaching process. The present invention uses vanadium shale ore as the leaching raw material, and on the basis of adding fluoride as a leaching aid in the prior art, additionally adds nitrate / nitrite as a leaching aid, which can effectively reduce the amount of acid used in the leaching process. The mechanism is as follows:

[0051] ① Nitrate / nitrite oxidation

[0052] In the leaching process of the present invention, nitrate ions form nitric acid under acidic conditions, and the nitric acid is adsorbed on the leaching reaction interface, which can oxidize low-valent vanadium in the vanadium shale ore mica into high-valent vanadium (such as +4, +5). 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.

[0053] ② Coordination of nitrate ions

[0054] 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, making the vanadium in the original ore easier to dissolve.

[0055] (2) Low consumption of leaching aid. The present invention leaches the vanadium shale ore 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 ore 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.

[0056] (3) High vanadium leaching rate. The present invention achieves the pre-destruction of the vanadium-containing mica structure in the original ore by introducing a nitrate / nitrite and fluoride coupled leaching system; the continuous circulation of beneficial components in the leaching solution in the leaching system strengthens the destructive effect of sulfuric acid and leaching aids on the mineral structure during the leaching process, and ultimately achieves an increase in the vanadium leaching rate.

[0057] (4) Environmentally friendly. The vanadium in the vanadium shale ore is mainly present in mica in the form of lattice substitution, in a low-valent state (such as +3 valence), with high stability and difficult to dissolve. Generally, a pre-roasting operation is required to destroy the mica structure in order to achieve the dissolution of vanadium under low-acid conditions. The present invention adopts a fully wet extraction process, and achieves pre-destruction and lattice distortion of mica minerals through nitrate / nitrite coupling with fluoride, thereby avoiding the generation of harmful gases during the roasting process and having environmentally friendly characteristics.

[0058] Therefore, the present invention has the characteristics of small acid dosage in the leaching process, small leaching aid consumption, high vanadium leaching rate and environmental friendliness. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below in conjunction with specific implementation methods, but is not intended to limit the scope of protection thereof.

[0060] A method for direct acid leaching of vanadium shale to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0061] Step 1: Ore crushing and grinding

[0062] The vanadium shale is crushed and ground to obtain raw ore powder.

[0063] Step 2: Batch leaching of raw ore powder

[0064] The raw ore powder is divided into n equal parts, where n is a natural number of 3 to 10, and leached in n batches in sequence.

[0065] The first batch of raw ore powder is mixed with water to obtain the first batch of mixed slurry.

[0066] Concentrated sulfuric acid is added to the first batch of mixed slurry and then slurried to obtain the first batch of leached slurry.

[0067] After adding the leaching aid to the first batch of leaching slurry and mixing the slurry, a leaching mixed slurry is obtained.

[0068] 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.

[0069] Starting from batch 2, follow these steps:

[0070] The raw ore powder is mixed with the circulating leaching agent produced in the previous batch and then slurried to obtain a mixed slurry.

[0071] 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.

[0072] A leaching aid is added to the secondary leaching slurry and then the slurry is adjusted to obtain a leaching mixed slurry.

[0073] 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.

[0074] In the nth batch, all the clear leaching liquid is used as the finished leaching liquid.

[0075] During the first batch of leaching, the mass ratio of concentrated sulfuric acid to raw ore powder was 0.20-0.25:1; for the remaining batches, the mass ratio of concentrated sulfuric acid to raw ore powder was 0.18-0.22:1.

[0076] In the first batch of leaching, the mass ratio of the raw ore powder to the leaching aid is 1:0.02-0.05; in the remaining batches, the mass ratio of the raw ore powder to the leaching aid is 1:0.015-0.04.

[0077] 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.

[0078] Step 3: Adjust the pH value of the leaching solution

[0079] All batches of finished product leachates are mixed, and the pH value is adjusted to 1.6-2.6 to obtain an adjusted leachate.

[0080] Sodium sulfite is added to the adjusted leaching solution, stirred, and filtered to obtain an extract solution and pH-adjusted residue.

[0081] Step 4: Solvent extraction and vanadium precipitation

[0082] 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.

[0083] 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.

[0084] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0085] 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.

[0086] 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.

[0087] Preferably, the 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%;

[0088] The vanadium content of mica minerals in vanadium shale accounts for 40 to 95 wt% of the total vanadium content.

[0089] Preferably, the particle size of the raw ore powder is less than 0.074 mm and accounts for 20 to 50 wt%.

[0090] Preferably, the extractant is one or more of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0091] 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.

[0092] Preferably, the stripping agent is a 1-2 mol / L sulfuric acid solution.

[0093] Preferably, the lean organic phase is recycled as the organic phase in step 4 after being regenerated.

[0094] In this specific implementation mode:

[0095] The chemical composition of each batch of leaching aid is the same;

[0096] The volume of each batch of leach slurry is equal;

[0097] Each batch of concentrated sulfuric acid has the same chemical composition;

[0098] The concentration of concentrated sulfuric acid is greater than 98wt%;

[0099] The lean organic phase is regenerated and recycled as an organic phase in step 4.

[0100] This will not be described in detail in the embodiments.

[0101] Example 1

[0102] A method for direct acid leaching of vanadium shale to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0103] Step 1: Ore crushing and grinding

[0104] The vanadium shale is crushed and ground to obtain raw ore powder.

[0105] Step 2: leaching of n batches of raw ore powder

[0106] The raw ore powder was divided into three equal parts and leached in three batches in sequence.

[0107] Step 2.1: Leaching of the first batch of raw ore powder

[0108] The first batch of raw ore 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 raw ore powder of 0.20:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0109] 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 raw ore powder: the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0110] 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.

[0111] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0112] The first batch of leaching aids comprises 70 wt% of fluoride and 30 wt% of sodium nitrate; the fluoride is calcium fluoride.

[0113] Step 2.2: Leaching of the second batch of raw ore powder

[0114] The second batch of raw ore 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 0.18:1 between the second batch of concentrated sulfuric acid and the second batch of raw ore 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.

[0115] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of raw ore powder to the second batch of leaching aid of 1:0.015 to obtain the second batch of leaching slurry.

[0116] 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.

[0117] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0118] Step 2.3: Leaching of the third batch of raw ore powder

[0119] The third batch of raw ore 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 0.18:1 between the third batch of concentrated sulfuric acid and the third batch of raw ore powder, and water with the same volume as the second batch of leachate is added to adjust the slurry to obtain the third batch of leaching slurry.

[0120] The third batch of leaching aid is added to the third batch of leaching slurry at a mass ratio of the third batch of raw ore powder to the third batch of leaching aid of 1:0.015 to obtain the third batch of leaching slurry.

[0121] 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.

[0122] The clear liquid from the third batch of leaching is all the liquid from the third batch of leaching.

[0123] The third batch of leachate enters the pH adjustment process as the finished leachate.

[0124] Step 3: Adjust the pH value of the leaching solution

[0125] 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.

[0126] Step 4: Solvent extraction and vanadium precipitation

[0127] 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.

[0128] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0129] The 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%.

[0130] The vanadium content of mica minerals in vanadium shale accounts for 40wt% of the total vanadium content.

[0131] The particle size of the raw ore powder is less than 0.074 mm, accounting for 20 wt%.

[0132] The extractant is di(2-ethylhexyl)phosphonate.

[0133] The organic phase is a mixture of 15 vol% of an extractant, 5 vol% of secondary octanol and 80 vol% of sulfonated kerosene.

[0134] The stripping agent is 1 mol / L sulfuric acid solution.

[0135] Example 2

[0136] A method for direct acid leaching of vanadium shale to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0137] Step 1: Ore crushing and grinding

[0138] The vanadium shale is crushed and ground to obtain raw ore powder.

[0139] Step 2: leaching of n batches of raw ore powder

[0140] The raw ore powder was divided into 4 equal parts and leached in 4 batches in sequence.

[0141] Step 2.1: Leaching of the first batch of raw ore powder

[0142] The first batch of raw ore 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 raw ore powder of 0.21:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0143] According to the mass ratio of the first batch of raw ore powder to the first batch of leaching aid of 1:0.03, the first batch of leaching aid is added to the first batch of leaching slurry, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0144] 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.

[0145] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0146] The first batch of leaching aids contains 75 wt% of fluoride and 25 wt% of sodium nitrite; the fluoride is sodium fluoride.

[0147] Step 2.2: Leaching of the second batch of raw ore powder

[0148] The second batch of raw ore 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 raw ore powder, and water with the same volume as the first batch of leachate is added to adjust the slurry to obtain the second batch of leaching slurry.

[0149] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of raw ore powder to the second batch of leaching aid of 1:0.02 to obtain the second batch of leaching slurry.

[0150] 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.

[0151] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0152] Step 2.3: Leaching of the third batch of raw ore powder

[0153] The third batch of raw ore 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 0.19:1 between the third batch of concentrated sulfuric acid and the third batch of raw ore powder, and water with the same volume as the second batch of leachate is added to adjust the slurry to obtain the third batch of leaching slurry.

[0154] The third batch of leaching aid is added to the third batch of leaching slurry at a mass ratio of 1:0.02 of the third batch of raw ore powder: the third batch of leaching aid to obtain the third batch of leaching mixed slurry.

[0155] 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.

[0156] The third batch of leachate enters the pH adjustment process as the finished leachate.

[0157] Step 2.4, leaching of the fourth batch of raw ore powder

[0158] The fourth batch of raw ore 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 0.19:1 between the fourth batch of concentrated sulfuric acid and the fourth batch of raw ore powder, and water with the same volume as the third batch of leachate is added to adjust the slurry to obtain the fourth batch of leaching slurry.

[0159] The fourth batch of leaching aid is added to the fourth batch of leaching slurry at a mass ratio of 1:0.02 of the fourth batch of raw ore powder: the fourth batch of leaching aid to obtain the fourth batch of leaching mixed slurry.

[0160] 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.

[0161] The clear liquid from the 4th batch of leaching is all the 4th batch of leaching liquid.

[0162] The fourth batch of leachate enters the pH adjustment process as the finished leachate.

[0163] Step 3: Adjust the pH value of the leaching solution

[0164] 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.

[0165] Step 4: Solvent extraction and vanadium precipitation

[0166] 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.

[0167] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0168] The 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%.

[0169] The vanadium content of mica minerals in vanadium shale accounts for 60wt% of the total vanadium content.

[0170] The particle size of the raw ore powder is less than 0.074 mm, accounting for 30 wt%.

[0171] The extractant is 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0172] 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.

[0173] The stripping agent is a 1.25 mol / L sulfuric acid solution.

[0174] Example 3

[0175] A method for direct acid leaching of vanadium shale to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0176] Step 1: Ore crushing and grinding

[0177] The vanadium shale is crushed and ground to obtain raw ore powder.

[0178] Step 2: leaching of n batches of raw ore powder

[0179] The raw ore powder was divided into 6 equal parts and leached in 6 batches in sequence.

[0180] Step 2.1: Leaching of the first batch of raw ore powder

[0181] The first batch of raw ore 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 raw ore powder of 0.22:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0182] According to the mass ratio of the first batch of raw ore powder to the first batch of leaching aid of 1:0.035, the first batch of leaching aid is added to the first batch of leaching slurry, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0183] 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.

[0184] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0185] 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.

[0186] Step 2.2: Leaching of the second batch of raw ore powder

[0187] The second batch of raw ore 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 raw ore powder, and water with the same volume as the first batch of leachate is added to adjust the slurry to obtain the second batch of leaching slurry.

[0188] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of raw ore powder to the second batch of leaching aid of 1:0.03 to obtain the second batch of leaching slurry.

[0189] 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.

[0190] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0191] …….

[0193] The process of leaching the second batch of raw ore powder described in step 2.2 is analogous to the process of leaching the fifth batch of raw ore powder.

[0194] Step 2.5: Leaching of the fifth batch of raw ore powder

[0195] The fifth batch of raw ore 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 0.20:1 between the fifth batch of concentrated sulfuric acid and the fifth batch of raw ore powder, and water with the same volume as the fourth batch of leachate is added to adjust the slurry to obtain the fifth batch of leaching slurry.

[0196] The fifth batch of leaching aid is added to the fifth batch of leaching slurry at a mass ratio of the fifth batch of raw ore powder to the fifth batch of leaching aid of 1:0.03 to obtain the fifth batch of leaching mixed slurry.

[0197] 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.

[0198] The fifth batch of leachate enters the pH adjustment process as the finished leachate.

[0199] Step 2.6, leaching of the sixth batch of raw ore powder

[0200] The sixth batch of raw ore 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 0.20:1 between the sixth batch of concentrated sulfuric acid and the sixth batch of raw ore powder, and water with the same volume as the fifth batch of leachate is added to adjust the slurry to obtain the sixth batch of leaching slurry.

[0201] The sixth batch of leaching aid was added to the sixth batch of leaching slurry at a mass ratio of the sixth batch of raw ore powder to the sixth batch of leaching aid of 1:0.03 to obtain the sixth batch of leaching mixed slurry.

[0202] 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.

[0203] The clear liquid from the 6th batch of leaching is all the 6th batch of leaching liquid.

[0204] The sixth batch of leachate enters the pH adjustment process as the finished leachate.

[0205] Step 3: Adjust the pH value of the leaching solution

[0206] 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.

[0207] Step 4: Solvent extraction and vanadium precipitation

[0208] 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.

[0209] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0210] The 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%.

[0211] The vanadium content of mica minerals in vanadium shale accounts for 70wt% of the total vanadium content.

[0212] The particle size of the raw ore powder is less than 0.074 mm, accounting for 35 wt%.

[0213] The extractant is a mixture of di(2-ethylhexyl)phosphonate and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0214] 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.

[0215] The stripping agent is a 1.5 mol / L sulfuric acid solution.

[0216] Example 4

[0217] A method for direct acid leaching of vanadium shale to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0218] Step 1: Ore crushing and grinding

[0219] The vanadium shale is crushed and ground to obtain raw ore powder.

[0220] Step 2: leaching of n batches of raw ore powder

[0221] The raw ore powder was divided into 8 equal parts and leached in 8 batches in sequence.

[0222] Step 2.1: Leaching of the first batch of raw ore powder

[0223] The first batch of raw ore 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 raw ore powder of 0.23:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0224] 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 raw ore powder: the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0225] 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.

[0226] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0227] The first batch of leaching aids contains 85 wt% of fluoride and 15 wt% of sodium nitrite; the fluoride is calcium fluoride.

[0228] Step 2.2: Leaching of the second batch of raw ore powder

[0229] The second batch of raw ore 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 0.21:1 of the second batch of concentrated sulfuric acid: the second batch of raw ore powder, and then 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.

[0230] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of raw ore powder to the second batch of leaching aid of 1:0.035 to obtain the second batch of leaching slurry.

[0231] 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.

[0232] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0233] …….

[0235] The process of leaching the second batch of raw ore powder described in step 2.2 is analogous to the process of leaching the seventh batch of raw ore powder.

[0236] Step 2.7, leaching of the 7th batch of raw ore powder

[0237] The 7th batch of raw ore powder is mixed with the 7th batch of circulating leaching agent, and the 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 according to the mass ratio of the 7th batch of concentrated sulfuric acid to the 7th batch of raw ore powder of 0.21:1, and then water with the same volume as the 6th batch of leachate is added, and the slurry is adjusted to obtain the 7th batch of leaching slurry.

[0238] The seventh batch of leaching aid was added to the seventh batch of leaching slurry at a mass ratio of the seventh batch of raw ore powder to the seventh batch of leaching aid of 1:0.035 to obtain the seventh batch of leaching mixed slurry.

[0239] 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.

[0240] The seventh batch of leachate enters the pH adjustment process as the finished leachate.

[0241] Step 2.8, leaching of the 8th batch of raw ore powder

[0242] The 8th batch of raw ore powder is mixed with the 8th batch of circulating leaching agent, and the 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 according to the mass ratio of the 8th batch of concentrated sulfuric acid to the 8th batch of raw ore powder of 0.21:1, and then water with the same volume as the 7th batch of leachate is added, and the slurry is adjusted to obtain the 8th batch of leaching slurry.

[0243] The eighth batch of leaching aid was added to the eighth batch of leaching slurry at a mass ratio of the eighth batch of raw ore powder to the eighth batch of leaching aid of 1:0.035 to obtain the eighth batch of leaching mixed slurry.

[0244] 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.

[0245] The clear liquid from the 8th batch of leachate is all the 8th batch of leachate.

[0246] The 8th batch of leachate enters the pH adjustment process as the finished leachate.

[0247] Step 3: Adjust the pH value of the leaching solution

[0248] 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.

[0249] Step 4: Solvent extraction and vanadium precipitation

[0250] 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.

[0251] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0252] The 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%.

[0253] The vanadium content of mica minerals in vanadium shale accounts for 80wt% of the total vanadium content.

[0254] The particle size of the raw ore powder is less than 0.074 mm, accounting for 40wt%.

[0255] The extractant is di(2-ethylhexyl)phosphonate.

[0256] 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.

[0257] The stripping agent is a 1.75 mol / L sulfuric acid solution.

[0258] Example 5

[0259] A method for direct acid leaching of vanadium shale to enhance vanadium extraction. The steps of the method described in this specific embodiment are:

[0260] Step 1: Ore crushing and grinding

[0261] The vanadium shale is crushed and ground to obtain raw ore powder.

[0262] Step 2: leaching of n batches of raw ore powder

[0263] The raw ore powder was divided into 10 equal parts and leached in 10 batches in sequence.

[0264] Step 2.1: Leaching of the first batch of raw ore powder

[0265] The first batch of raw ore 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 raw ore powder of 0.25:1, and the slurry is adjusted to obtain the first batch of leaching slurry.

[0266] 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 raw ore powder to the first batch of leaching aid, and the slurry is adjusted to obtain the first batch of leaching mixed slurry.

[0267] 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.

[0268] The first batch of leachate enters the pH adjustment process as the finished leachate.

[0269] The first batch of leaching aids comprises 90 wt % of fluoride and 10 wt % of sodium nitrate; the fluoride is sodium fluoride.

[0270] Step 2.2: Leaching of the second batch of raw ore powder

[0271] The second batch of raw ore 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 0.22:1 between the second batch of concentrated sulfuric acid and the second batch of raw ore powder, and water with the same volume as the first batch of leachate is added to adjust the slurry to obtain the second batch of leaching slurry.

[0272] The second batch of leaching aid is added to the second batch of leaching slurry at a mass ratio of the second batch of raw ore powder to the second batch of leaching aid of 1:0.04 to obtain the second batch of leaching slurry.

[0273] 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.

[0274] The second batch of leachate enters the pH adjustment process as the finished leachate.

[0275] …….

[0276] The process of leaching the second batch of raw ore powder described in step 2.2 is analogous to the process of leaching the ninth batch of raw ore powder.

[0277] Step 2.9, leaching of the ninth batch of raw ore powder

[0278] The 9th batch of raw ore powder is mixed with the 9th batch of circulating leaching agent, and the 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 according to the mass ratio of the 9th batch of concentrated sulfuric acid to the 9th batch of raw ore powder of 0.22:1, and then water with the same volume as the 8th batch of leachate is added, and the slurry is adjusted to obtain the 9th batch of leaching slurry.

[0279] The ninth batch of leaching aid was added to the ninth batch of leaching slurry at a mass ratio of the ninth batch of raw ore powder to the ninth batch of leaching aid of 1:0.04 to obtain the ninth batch of leaching mixed slurry.

[0280] 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.

[0281] The 9th batch of leachate enters the pH adjustment process as the finished leachate.

[0282] Step 2.10, leaching of the 10th batch of raw ore powder

[0283] The 10th batch of raw ore powder is mixed with the 10th batch of circulating leaching agent, and the 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 0.22:1 between the 10th batch of concentrated sulfuric acid and the 10th batch of raw ore powder, and then water with the same volume as the 9th batch of leachate is added, and the slurry is adjusted to obtain the 10th batch of leaching slurry.

[0284] The tenth batch of leaching aid is added to the tenth batch of leaching slurry at a mass ratio of the tenth batch of raw ore powder to the tenth batch of leaching aid of 1:0.04 to obtain the tenth batch of leaching mixed slurry.

[0285] 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.

[0286] The 10th batch of leaching clear liquid is all the 10th batch of leaching liquid.

[0287] The 10th batch of leachate enters the pH adjustment process as the finished leachate.

[0288] Step 3: Adjust the pH value of the leaching solution

[0289] 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.

[0290] Step 4: Solvent extraction and vanadium precipitation

[0291] 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.

[0292] The vanadium-rich solution is subjected to ammonium salt precipitation and deammoniation to obtain vanadium pentoxide.

[0293] The 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%.

[0294] The vanadium content of mica minerals in vanadium shale accounts for 95wt% of the total vanadium content.

[0295] The particle size of the raw ore powder is less than 0.074 mm, accounting for 50wt%.

[0296] The extractant is 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0297] The organic phase is a mixture of 25 vol% of an extractant, 10 vol% of secondary octanol and 65 vol% of sulfonated kerosene.

[0298] The stripping agent is a 2 mol / L sulfuric acid solution.

[0299] Compared with the prior art, this specific implementation has the following beneficial effects:

[0300] (1) Small amount of acid used in the leaching process. This specific implementation method uses vanadium shale ore as the leaching raw material. On the basis of adding fluoride as a leaching aid in the prior art, nitrate / nitrite is additionally added as a leaching aid, which can effectively reduce the amount of acid used in the leaching process. The mechanism is as follows:

[0301] ① Nitrate / nitrite oxidation

[0302] In the leaching process of this specific embodiment, nitrate ions form nitric acid under acidic conditions, and the nitric acid is adsorbed on the leaching reaction interface, which can oxidize the low-valent vanadium in the vanadium shale ore mica into a high-valent state (such as +4, +5). 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.

[0303] ② Coordination of nitrate ions

[0304] 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, making the vanadium in the original ore easier to dissolve.

[0305] (2) Low consumption of leaching aid. This specific embodiment leaches the vanadium shale ore 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 ore 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 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 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.

[0306] (3) High vanadium leaching rate. This specific implementation method achieves the pre-destruction of the vanadium-containing mica structure in the original ore by introducing a nitrate / nitrite and fluoride coupled leaching system; the continuous circulation of beneficial components in the leaching solution in the leaching system strengthens the destructive effect of sulfuric acid and leaching aids on the mineral structure during the leaching process, and ultimately achieves an increase in the vanadium leaching rate.

[0307] (4) Environmentally friendly. The vanadium in the vanadium shale ore is mainly present in mica in the form of lattice substitution, in a low-valent state (such as +3 valence), with high stability and difficult to dissolve. Generally, a pre-roasting operation is required to destroy the mica structure before vanadium can be dissolved under low-acid conditions. This specific embodiment adopts a fully wet extraction process, and achieves pre-destruction and lattice distortion of mica minerals through nitrate / nitrite coupling with fluoride, avoiding the generation of harmful gases during the roasting process, and is environmentally friendly.

[0308] Therefore, the specific implementation method has the characteristics of small acid dosage in the leaching process, small consumption of leaching aid, high vanadium leaching rate and environmental friendliness.

Claims

1. A method for direct acid leaching of vanadium shale to enhance vanadium extraction, characterized in that The specific steps of the method are: Step 1: Ore crushing and grinding Crushing and grinding the vanadium shale to obtain raw ore powder; Step 2: Batch leaching of raw ore powder The raw ore powder is divided into n equal parts, where n is a natural number of 3 to 10, and leached in n batches in sequence; Mixing the first batch of raw ore 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 raw ore 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 raw ore powder is 0.20-0.25:1; in the remaining batches, the mass ratio of concentrated sulfuric acid to raw ore powder is 0.18-0.22:1; In the first batch of leaching, the mass ratio of the raw ore powder to the leaching aid is 1:0.02-0.05; in the remaining batches, the mass ratio of the raw ore 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 direct 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 direct acid leaching of vanadium shale 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 direct acid leaching of vanadium shale according to claim 1, characterized in that: The 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%; The vanadium content of mica minerals in vanadium shale accounts for 40 to 95 wt% of the total vanadium content.

5. The method for direct acid leaching of vanadium shale according to claim 1, characterized in that: The particle size of the raw ore powder is less than 0.074 mm, accounting for 20-50 wt%.

6. The method for direct acid leaching of vanadium shale 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 direct 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 direct 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 direct 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.