Method for purifying vanadium pentoxide from stone coal with high environmental protection and low energy consumption

Abstract

A method for purifying vanadium pentoxide from stone coal with high environmental protection and low energy consumption is provided, including: tightly mixing vanadium-bearing stone coal particles, herbaceous biomass with multiple size specifications, delignified lignin, fermentation bacterial material and anoxic photoferrous iron-oxidizing bacteria, and naturally fermenting in a summer environment with sunlight exposure at the top of the pile; collecting the fermentation exudate and performing precipitation and filtration treatments, extracting the filtrate with an organic extractant, and then back-extracting with an inorganic extractant to obtain a purified solution, and subjecting the purified solution to spray pyrolysis under an oxidizing atmosphere to obtain vanadium pentoxide. The fermentation bacterial material is mushroom residue or mushroom bacterial solution obtained by mashing and diluting mushrooms; the anoxic photoferrous iron-oxidizing bacteria are Rhodomicrobium vannielii. The content of V2O5 in the vanadium-bearing stone coal particles is ≥0.9%, and the content of Fe2O3 is ≥3.9%.

Description

Technical Field

[0001] The present invention relates to the field of vanadium extraction from vanadium-containing ores, and particularly to a method for extracting high-purity vanadium pentoxide from stone coal mines with high environmental protection and low energy consumption. Background Art

[0002] Vanadium extraction from stone coal mines is an important source for obtaining vanadium pentoxide. In the past, there were methods such as roasting-water leaching, roasting-acid leaching, and direct acid leaching for vanadium extraction from stone coal mines. The roasting was often carried out at a high temperature above 800 °C, with high energy consumption. And the acid leaching mainly used sulfuric acid for leaching, and also involved environmental protection issues of inorganic acids. The reflux ratio and recovery treatment were relatively complex. To a large extent, natural conditions were applied, and there was still a lack of research on purification methods for vanadium pentoxide with environmental protection and low energy consumption. Summary of the Invention

[0003] In view of the above problems, the present invention is developed, and its purpose is to provide a method for purifying vanadium pentoxide from stone coal mines with high environmental protection and low energy consumption.

[0004] The method for purifying vanadium pentoxide from stone coal mines with high environmental protection and low energy consumption provided by the present invention includes: tightly mixing vanadium-containing stone coal particles, grass and wood biomass with multiple size specifications, defibrinated lignin, fermentation bacterial material, and anoxic photoferrous-oxidizing bacteria, and naturally fermenting in a summer environment with sunlight exposure on the pile top; the vanadium-containing stone coal particles are stone coal powders collected from an ore-bearing layer rich in V2O5 and Fe2O3, crushed and ground to a fineness of less than 0.1 mm, and with a particle size greater than 120 mesh ≥ 80%; the grass and wood biomass with multiple size specifications consists of small-size grass and wood biomass obtained by crushing woody biomass into a size specification of 1-10 mm in length, width, and thickness, and large-size grass and wood biomass obtained by cutting herbaceous biomass into a size specification of 100-300 mm in length; the defibrinated lignin is prepared by defibrinating powdery grass and wood biomass with cellulase and hemicellulase. The powdery grass and wood biomass is prepared by coarsely crushing woody biomass and / or herbaceous biomass to a particle size of 2-4 cm and then finely crushing it to a particle size of 0.4-0.7 cm; collecting the fermentation exudate and performing precipitation and filtration treatments, extracting the filtrate with an organic extractant, and then back-extracting it with an inorganic extractant to obtain a purified solution, and subjecting the purified solution to spray pyrolysis in an oxidizing atmosphere to obtain vanadium pentoxide. Wherein the fermentation bacterial material is mushroom residue or mushroom bacterial solution obtained by mashing and diluting mushrooms; the anoxic photoferrous-oxidizing bacteria is Rhodomicrobium vannielii. The content of V2O5 in the vanadium-containing stone coal particles is ≥ 0.9%, and the content of Fe2O3 is ≥ 3.9%.

[0005] It also includes: mixing small-sized herbaceous biomass and defibrinated lignin with fermentation bacterial materials, performing a water balance treatment at a temperature of 45 - 60°C to obtain a moisture content of 6 - 12%; drying or sun-drying large-sized herbaceous biomass and then only performing a spraying treatment with a spraying amount of 0.5 - 3% of the mass of the biomass, or not performing a spraying treatment; mixing and stirring the fermented materials obtained after the water balance treatment with large-sized herbaceous biomass, stacking in multiple layers and dispersedly arranging fermentation bacterial materials and anoxic photosynthetic ferrous-oxidizing bacteria on the surface of each layer, and fermenting in a temperature environment of 30 - 40°C in summer after stacking. Among them, the woody biomass is from wood processing residues, horticultural leftovers, recycled boards, and / or natural wood, and the herbaceous biomass is from wheat straw, rice straw, and / or thin bamboo. The stacking is carried out in multiple layers, preferably 20 - 30 layers, and fermentation bacterial materials and anoxic photosynthetic ferrous-oxidizing bacteria are dispersedly arranged on the surface of each layer. A transparent or semi-transparent heavy object is pressed on the top of the stack to compact the laid materials, and it is left standing for 3 - 5 weeks.

[0006] For every 100 parts by mass of powdered herbaceous biomass, 3 - 5 parts by mass of cellulase and 2 - 4 parts by mass of hemicellulase are used for defibrination treatment. The mass ratio of vanadium-bearing stone coal particles to all plant materials is (1 - 2):10. The mass ratio of large-sized herbaceous biomass, small-sized herbaceous biomass, and defibrinated lignin is 1:(1 - 1.5):(2 - 2.5). The mass ratio of fermentation bacterial materials to all plant materials is (0.15 - 0.2):1000. The mass ratio of anoxic photosynthetic ferrous-oxidizing bacteria to vanadium-bearing stone coal particles is (0.2 - 0.3):100.

[0007] It also includes: allowing the collected exudate to stand for 10 - 30 min, removing the precipitate and then diluting and stirring with deionized water at a volume ratio of 1:5, standing again for 30 - 50 min to remove the precipitate, and then removing organic biomass through a semi-permeable membrane to obtain a purified acid leaching solution; adjusting the pH value of the acid leaching solution to 0.65 with KOH, using a mixed solvent of 40% N263 + 20% TBP + 40% sulfonated kerosene as the extractant, performing extraction for 1 min with a phase ratio O / A = 1:2, and performing six-stage countercurrent extraction to obtain a mixed loaded organic phase; washing the mixed loaded organic phase twice with 0.1 mol / L HCl, using 8 moL / L HCl as the stripping agent, and under the conditions of a phase ratio O / A = 4:1 and a stripping time of 3 min, obtaining a vanadium-rich solution through four-stage countercurrent stripping; spray pyrolyzing the vanadium-rich solution in the air to obtain a vanadium pentoxide product with a product purity of 99.91%.

[0008] According to the present invention, this method does not require overly precise industrial-level control, and can achieve low cost, low energy consumption, high environmental protection, and simple and convenient operation.

[0009] Under appropriate aerobic or anaerobic conditions, grass and wood are fermented by a fermenting agent to produce oxalic acid. The multiple aqueous environments increase the conditions for diluting high-concentration oxalic acid. When a microenvironment with an acidity exceeding 2 appears, leaching of vanadium ore occurs. High-valent vanadium iron will catalyze the formation of oxalic acid. When iron is leached by acid, it will be reduced to low-valent iron by oxalic acid. Since Vannielia microbacteria have the ability to oxidize Fe(II) to Fe(III), the stock of high-valent iron will be continuously restored in a certain microenvironment, thereby promoting the oxidation of cellulose. During the process of leaching vanadium from vanadium ore and reducing vanadium iron, oxalic acid will release H2O and CO2. CO2 can be used as a nutrient for the reproduction of Vannielia microbacteria and promote the formation of an anaerobic environment. As CO2 is released during the process of leaching vanadium iron, the reproduction of Vannielia microbacteria accelerates, and thus a mutually promoting effect is presented within an appropriate range. Detailed implementation mode

[0010] The terms "comprising" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion, so that a process, method, system, product or device comprising a series of units does not have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices. Without special statement, the numerical range "A to B" means above A (greater than or equal to A) and below B (less than or equal to B). When referring to normal temperature or room temperature, it usually means between 22 and 25 °C, and sometimes between 20 and 28 °C according to different processes. When there is no temperature limit for some processes, it is generally considered to be carried out at the said normal temperature or room temperature. In different fields of the actual industry, there are different understandings of normal temperature or room temperature. However, for the implementation and application of the patent law, the specific applicable range should be determined according to the achievement of the invention purpose, and is not limited to the narrow experience of a certain field. Those skilled in the art should also understand that when referring to the actual meaning at a certain temperature, the control of the temperature is not absolutely constant, and there will often be a certain fluctuation. The appropriate degree of this fluctuation should be judged based on the achievement of the experimental purpose.

[0011] The present invention provides a method for extracting vanadium from vanadium-bearing stone coal, especially relating to the purification process of vanadium pentoxide. The following will further elaborate on the present invention in combination with specific embodiments. The technical solution of the present invention is not limited to the specific embodiments listed below, and also includes any possible combinations of the specific embodiments.

[0012] This method first mixes and compresses vanadium-bearing stone coal raw materials, non-dissociated grass and wood biomass, decellulosed lignin, fermenting bacterial liquid, and anoxic photoferrous iron-oxidizing bacteria, and naturally ferments under the light environment on the top layer.

[0013] The vanadium-bearing stone coal raw materials are preferably collected from the ore-bearing layer rich in V2O5 and Fe2O3. The vanadium-bearing raw materials are crushed to a certain particle size by a crusher, and then ground to a certain fineness by a ball mill or a Raymond mill. The grinding fineness is less than 0.1 mm, and the particle size is greater than 120 mesh ≥ 80%.

[0014] A large proportion of vanadium in the stone coal deposit exists in the form of V(IV) in mica minerals, and a small proportion of V(III) exists in the form of isomorphous substitution of A1 in the mica lattice. 3+ It exists in the form of ions. The experimental sampling of the present invention is the Yangjiashan vanadium deposit, which is a typical sedimentary origin. The ore-bearing horizon of the ore body is the black shale series at the bottom of the Hetang Formation of the Cambrian System. The Cambrian black rock series type vanadium deposit is widely distributed in China. Therefore, the present invention has a relatively wide application basis.

[0015] According to the results of the chemical full analysis of the combined samples in the known Yangjiashan vanadium mining area (determined by an iCAP-Q type inductively coupled plasma mass spectrometer (ICP-MS)), the V2O5 content of various ores is 1.185% for carbonaceous-vanadium ore, 1.274% for carbonaceous-vanadium ore, 1.014% for carbonaceous-vanadium-bearing ore, 0.990% for carbonaceous-vanadium-bearing ore, and 1.274% for siliceous-vanadium ore; the Fe2O3 content results are 3.45% for carbonaceous-vanadium ore, 4.29% for carbonaceous-vanadium ore, 3.13% for carbonaceous-vanadium-bearing ore, 2.97% for carbonaceous-vanadium-bearing ore, and 3.82% for siliceous-vanadium ore, which is an ideal stone coal source.

[0016] The herbaceous biological material includes the plant biomass of natural growing woody or other plant types, and also includes the raw materials obtained by certain physical or chemical processing to complete processes such as fragmentation and dissociation. Lignin is contained in the plant cell wall. Due to symbiosis with cellulose and hemicellulose, its content only accounts for 10% - 20% of the vegetation. Lignin can be fermented in the natural environment, but the proportion of lignin in natural plant resources is not high. In this embodiment, 3 - 5 parts by mass of cellulase and 2 - 4 parts by mass of hemicellulase are used to perform defibrination treatment on the herbaceous biological material to obtain defibrinated lignin. In order to achieve good treatment effects, the material is crushed by a coarse crusher to form a material with a particle size of 2 - 4 cm, and after drying in the sun, it is transferred to a fine crusher for secondary crushing, and the particle size of the material is crushed to 0.4 - 0.7 cm.

[0017] To avoid creating a relatively uniform fermentation environment caused by high-purity lignin, non-dissociated herbaceous biomass and defibrinated lignin are simultaneously mixed into the material, and through the voids of the plant biomass itself, a complex atmosphere environment is created during the mixing process and the continuous reaction process.

[0018] More specifically, in the experiment of the present invention, recycled wood such as wood processing waste, gardening leftovers, recycled boards, and / or natural wood are used as the first non-dissociated plant biomass source, and are crushed into a size specification of 1 to 10 mm in length, width and thickness to obtain small-sized non-dissociated biomass; natural plant materials such as wheat straw, rice straw, and thin bamboo are used as the second non-dissociated fiber biomass source, and are cut into a size specification of 100 to 300 mm to obtain large-sized non-dissociated biomass.

[0019] On the other hand, the above-mentioned different cellulose biomasses are subjected to different humidification treatments to create a complex water environment. At the same time, the fermentation performance at different stages is controlled in conjunction with the humidification treatment to create a complex microbial environment.

[0020] In the present invention, small-sized plant biomass and defiberized lignin were mixed with fermentation liquid and subjected to water balance treatment at a temperature of 45-60° C. to obtain a moisture content of 6-12%. At this stage, lignin was degraded by thermophilic fungi naturally contained in the plant.

[0021] The large-sized grass biomass is only sprayed after being dried or sun-dried, and the spraying amount is 0.5-3% of the mass of the biomass raw material, or no spraying is required.

[0022] The fermented materials and large-sized grass biomass after water balance treatment are piled with fermented bacterial liquid. In the summer, at a temperature of 30-40℃, the mesophilic microorganisms such as actinomycetes naturally contained in the plants are active. If the temperature is maintained for a period of time, the mesophilic microorganisms will maintain decomposition activity for a longer period of time, degrading lignin and humus to a greater extent. As the fermentation proceeds, the temperature in the pile rises locally, providing conditions for the degradation of thermophilic fungi.

[0023] In the experiment of the present invention, the fermentation agent can be microorganisms naturally contained in plants, or can be prepared by microorganisms, such as mushroom residue or mushroom powder.

[0024] Anoxic phototrophic ferrous oxidizing bacteria can use light energy to fix CO2 and synthesize organic matter, and the genus is not limited, such as Chlorobium, Rhodovulum, Rhodoricrobium vannielit and Rhodopseudomonas in Proteobacteria. In the experiment of the present invention, Rhodoricrobium vannielit was sampled from the surface of freshwater sediment with light as an inoculum, and Fe(II) was added at a dosage of 8 mmol·L for enrichment culture for 1 hour in a light anoxic environment. The culture medium used was 9K culture medium, and the culture conditions were 28-30°C and pH 7.0-7.5.

[0025] Example 1

[0026] (1) Take 100 kg of carbonaceous - vanadium ore from Yangjiashan vanadium deposit (the measured V2O5 content is 1.23%, and the Fe2O3 content is 4.30%). After crushing and ball - milling processes, vanadium - containing ore powder with a fineness of 0.08 mm and a particle size greater than 120 mesh and containing 92% is obtained.

[0027] (2) Take 2500 kg of wood processing residues, 200 kg of recycled boards, 1000 kg of dried fine bamboo, 800 kg of wheat straw, and 500 kg of poplar wood. Crush them through a coarse crusher to form materials with a particle size of 2 - 4 cm. After drying in the sun, transfer them to a fine crusher for secondary crushing, and crush the particle size of the materials to 0.4 - 0.7 cm. Through 150 kg of cellulase and 100 kg of hemicellulase for defibrination treatment, about 520 kg of defibrinated lignin is obtained.

[0028] (3) Take 150 kg of wood processing residues, 60 kg of recycled boards, and 50 kg of poplar wood and plane them into fragments with a length, width, and thickness of 1 - 10 mm.

[0029] (4) Put (2) and (3) together with 100 g of mushroom residue into a drying room and carry out a water - balance treatment at a temperature of 60 °C until the moisture content reaches 10%.

[0030] (5) Take a total of 250 kg of dried wheat straw, rice straw, and fine bamboo, spray 5 L of water irregularly, and then cut them to an average size of 200 mm.

[0031] (6) After mixing (4) and (5) evenly, lay them in 20 layers in a fermentation tank isolated from the environment. On the surface of each layer of the laid material, disperse 100 g of mushroom residue and 300 g of Rhodomicrobium vannielii.

[0032] (7) Press 200 kg of tempered transparent glass plates on the top of the laid material to compact the laid material. After standing for 4 weeks in a temperature environment of 30 - 40 °C in summer, collect 132.5 L of the exudate at the bottom.

[0033] Example 2

[0034] (1) Take 150 kg of carbonaceous - vanadium ore from Yangjiashan vanadium deposit (the measured V2O5 content is 1.22%, and the Fe2O3 content is 4.20%). After crushing and ball - milling processes, vanadium - containing ore powder with a fineness of 0.07 mm and a particle size greater than 120 mesh and containing 89% is obtained.

[0035] (2) Take 2000 kg of wood processing residues, 400 kg of recycled boards, 800 kg of sun-dried wheat straw, and 800 kg of sun-dried rice straw, and crush them through a coarse crusher to form materials with a particle size of 2 - 4 cm. After drying, transfer them to a fine crusher for secondary crushing to reduce the particle size of the materials to 0.4 - 0.6 cm. Conduct defibration treatment with 150 kg of cellulase and 100 kg of hemicellulase to obtain approximately 430 kg of defibrated lignin.

[0036] (3) Take 100 kg of wood processing residues, 50 kg of recycled boards, and 100 kg of poplar wood, and shred them into fragments with a length, width, and thickness of 1 - 9 mm.

[0037] (4) Place (2) and (3) along with 100 g of mushroom residue in a drying chamber and conduct a water balance treatment at a temperature of 50 °C until the moisture content reaches 8%.

[0038] (5) Take a total of 250 kg of sun-dried wheat straw, rice straw, and thin bamboo, spray 7.5 L of water irregularly, and cut them to an average size of 250 mm.

[0039] (6) After mixing (4) and (5) evenly, lay them in 20 layers in a fermentation tank isolated from the environment. Disperse 100 g of mushroom residue and 200 g of Microbacterium vanneii on the surface of each layer of the laid material.

[0040] (7) Press down 250 kg of tempered transparent glass plates on the top of the laid material to compact the laid material. Let it stand for 4 weeks in a temperature environment of 30 - 40 °C in summer, and collect 128.7 L of the exudate at the bottom.

[0041] Example 3

[0042] (1) Take 200 kg of carbonaceous - vanadium ore from the Yangjiashan vanadium deposit (the measured V2O5 content is 1.24%, and the Fe2O3 content is 4.31%), and obtain vanadium - containing ore powder with a fineness of 0.09 mm, a particle size greater than 120 mesh, and a content of 85% through crushing and ball - milling processes.

[0043] (2) Take 1000 kg of wood processing residues, 2000 kg of recycled boards, 800 kg of sun - dried thin bamboo, and 200 kg of poplar wood, and crush them through a coarse crusher to form materials with a particle size of 2 - 4 cm. After drying, transfer them to a fine crusher for secondary crushing to reduce the particle size of the materials to 0.4 - 0.6 cm. Conduct defibration treatment with 250 kg of cellulase and 200 kg of hemicellulase to obtain approximately 620 kg of defibrated lignin.

[0044] (3) Take 100 kg of wood processing residues, 50 kg of recycled boards, and 100 kg of poplar wood, and shred them into fragments with a length, width, and thickness of 1 - 8 mm.

[0045] (4) Mix (2) and (3) with 50 g of mushroom residue and place them in a drying chamber for water balance treatment at a temperature of 45 °C until the moisture content reaches 6%.

[0046] (5) Take 250 kg of sun-dried wheat straw, rice straw, and thin bamboo without spraying treatment, and cut them to an average size of 150 mm.

[0047] (6) After mixing (4) and (5) evenly, lay them in 30 layers in a fermentation tank isolated from the environment. On the surface of each layer of the laid material, disperse 120 g of mushroom liquid and 100 g of Micrococcus vannielii.

[0048] (7) Press 250 kg of tempered transparent glass plates on the top of the laid material to compact it. After standing for 4 weeks in a temperature environment of 28 - 42 °C in summer, collect 100.7 L of the exudate at the bottom.

[0049] Comparative Example 1

[0050] (1) Take 100 kg of carbonaceous - vanadium ore from the Yangjiashan vanadium deposit (the measured V2O5 content is 1.23% and the Fe2O3 content is 4.30%). After crushing and ball - milling processes, obtain vanadium - containing ore powder with a fineness of 0.08 mm, a particle size greater than 120 mesh, and a content of 92%.

[0051] (2) Crush 2500 kg of wood processing residues, 200 kg of recycled boards, 1000 kg of sun - dried thin bamboo, 800 kg of wheat straw, and 500 kg of poplar wood through a coarse crusher to form materials with a particle size of 2 - 4 cm. After drying, transfer them to a fine crusher for secondary crushing to reduce the particle size of the materials to 0.4 - 0.7 cm. Through treatment with 150 kg of cellulase and 100 kg of hemicellulase, obtain approximately 510 kg of defibrated lignin.

[0052] (3) Shred 150 kg of wood processing residues, 50 kg of recycled boards, and 50 kg of poplar wood into fragments with dimensions of 1 - 10 mm in length, width, and thickness.

[0053] (4) Mix (2) and (3) with 100 g of mushroom residue and place them in a drying chamber for water balance treatment at a temperature of 60 °C until the moisture content reaches 10%.

[0054] (5) Take 250 kg of sun - dried wheat straw, rice straw, and thin bamboo, spray 5 L of water irregularly, and then cut them to an average size of 200 mm.

[0055] (6) After mixing (4) and (5) evenly, lay them in 20 layers in a fermentation tank isolated from the environment. On the surface of each layer of the laid material, only disperse 100 g of mushroom residue.

[0056] (7) Place a 200 kg tempered transparent glass plate on top of the laid material to press the material tightly. After standing for 4 weeks in a temperature environment of 30 - 40 °C in summer, collect 127.5 L of the exudate at the bottom.

[0057] Comparative Example 2

[0058] (1) Take 100 kg of carbonaceous - vanadium ore from the Yangjiashan vanadium deposit (the measured V2O5 content is 1.23% and the Fe2O3 content is 4.30%). After crushing and ball - milling processes, obtain vanadium - containing ore powder with a fineness of 0.08 mm, a particle size greater than 120 mesh, and a content of 92%.

[0059] (2) Crush 5000 kg of wood processing residues, 400 kg of recycled boards, 2000 kg of dried fine bamboo, 1600 kg of wheat straw, and 1000 kg of poplar wood through a coarse crusher to form materials with a particle size of 2 - 4 cm. After drying, transfer them to a fine crusher for secondary crushing, and crush the particle size of the materials to 0.4 - 0.7 cm. Through 300 kg of cellulase and 200 kg of hemicellulase for defibrination treatment, obtain approximately 1200 kg of defibrinated lignin.

[0060] (3) Place (2) and 100 g of mushroom residue in a drying room and conduct a water - balance treatment at a temperature of 60 °C until the moisture content reaches 12%.

[0061] (4) Layer - place (3) 20 times in a fermentation tank isolated from the environment. Disperse 100 g of mushroom residue and 300 g of Rhodomicrobium vannielii on the surface of each layer of the laid material.

[0062] (5) Place a 200 kg tempered transparent glass plate on top of the laid material to press the material tightly. After standing for 4 weeks in a temperature environment of 30 - 40 °C in summer, collect 220.5 L of the exudate at the bottom.

[0063] Detect and analyze the materials and exudate in the fermentation tank after the reaction in each case. The results are shown in Table 1.

[0064] Table 1

[0065] Exudate ions Residual V content V leaching rate Residual Fe content Fe leaching rate Example 1 V(IV), Fe(II,III), Mg, Na, Al 0.86％ 30.11％ 2.96％ 31.16％ Example 2 V(IV), Fe(II,III), Mg, Na, Al 0.87％ 28.92％ 2.90％ 30.88％ Example 3 V(IV), Fe(II,III), Mg, Na, Al 0.89％ 27.53％ 3.07％ 28.60％ Comparative Example 1 V(IV), Fe(II), Mg, Na, Al 0.89％ 27.64％ 3.12％ 27.40％ Comparative Example 2 V(IV), Fe(II,III), Mg, Na, Al 1.21％ 1.62％ 4.23％ 1.63％

[0066] According to the results, the leaching rate of ferrovanadium can reach about 30%. Although it is still lower than the previous acid leaching rate of 60-70%, this method does not require overly precise industrial-level control, and can achieve low cost, low energy consumption, high environmental protection and simple operation. The mechanism of this method cannot be fully quantitatively analyzed, but it is speculated that it is related to the configuration of complex atmosphere environment and water environment, creating opportunities for the synergistic cooperation of the microenvironment within the system. Under appropriate aerobic or anaerobic conditions, grass is fermented by the fermenting agent to produce oxalic acid. Oxalic acid has high hygroscopicity, which can cause different acid concentrations in the local environment. Coupled with the multiple water-containing environments of the system itself, the chance of high-concentration oxalic acid being diluted is increased. When a microenvironment with an acidity exceeding 2 appears, it will have a good leaching effect on vanadium ore. Comparing with Comparative Example 2, when completely using lignin without fibers as the raw material, considering the lack of spatial difference, the moisture content is too low and uniform, and the chance of meeting the metal leaching conditions is small. Comparing with Comparative Example 1, in the case of not configuring Microbacterium vanneilii, the leaching rate of ferrovanadium decreases. It is speculated that high-valent ferrovanadium will catalyze the formation of oxalic acid. When iron is leached by acid, it will be reduced to low-valent iron by oxalic acid. Since Microbacterium vanneilii has the ability to oxidize Fe(II) to Fe(III), the stock of high-valent iron will be continuously restored in a certain microenvironment, thus promoting the oxidation of cellulose. During the process of oxalic acid leaching from vanadium ore and reducing ferrovanadium, H2O and CO2 will be released. CO2 can be used as the breeding nutrient of Microbacterium vanneilii and promote the formation of anaerobic environment. As CO2 is released during the process of leaching ferrovanadium, the reproduction of Microbacterium vanneilii accelerates, showing a mutually promoting effect within an appropriate range. In addition, the effects of light and pressure are also considered. Microbacterium vanneilii can grow under anaerobic, microaerobic to aerobic conditions. By pressing transparent tempered glass on the top of the material, not only can the material be compacted and internal pressure be provided, but also different brightness changes can be created from top to bottom. In addition, the optimal growth temperature of this bacterium is 30 °C, and the fermenting bacterial material also includes medium- and low-temperature bacteria. In this implementation, a simulation test of summer temperature environment is carried out. In actual application, different regions in the north and south can choose the appropriate time for the growth of this bacterium according to the climate conditions, so as to achieve natural fermentation without additional heating to achieve environmental protection effects. In addition, the growth pH of Microbacterium vanneilii is 5.2-7.5, and the optimum is 6.0. Even if oxalic acid is continuously fermented in the material, due to the imbalance of the internal water environment, a large number of opportunities are created for the acid-base growth environment of this bacterium. Especially, the release and utilization process of H2O in the reaction continuously adjusts the microscopic water environment. In order to avoid destroying the unbalanced microenvironment, this test avoids turning and keeps still throughout the process.

[0067] Both Fe(II) and Fe(III) were detected in the collected exudate. It is considered that oxalic acid reduces ferric iron, and the iron-oxidizing bacteria in the exudate lose their breeding environment. Therefore, the collected exudate needs to be left standing for the reduction to complete. In addition, the detected V in the exudate is tetravalent V(IV). It is considered that the excessive presence of oxalic acid affects VO2 +For the reduction effect, V mainly exists as VOC2O4 and VO(C2O4)2 in oxalic acid 2- in the form, and the coordination reaction is as follows.

[0068] VO 2+ + C2O4 2- = VOC2O4

[0069] VOC2O4 + C2O4 2- = VO(C2O4)2 2-

[0070] The leachate also contains other Fe 2+ , Mg, Al, Na, K, P, Si and other ionic impurities, as well as oxalate and organic biomass. Depending on the origin of the vanadium ore, the impurity content often varies greatly, but especially Fe 2+ , Mg, Al, Na are the main impurities. The impurity components and concentrations of the collected liquid in Example 1 were detected as shown in Table 2.

[0071] Table 2

[0072]

[0073] For the separation of Fe 2+ , Mg, Al, Na, K, P, Si, for example, the extraction process in previous studies can be referred to. Here is an example.

[0074] (1) After the leachate collected in Example 1 was left standing for 30 min, the precipitate was removed, and then it was diluted and stirred with deionized water with a volume ratio of 1:5. After standing for 10 min again to remove the precipitate, the organic biomass was removed through a semipermeable membrane to obtain the acid leaching solution for vanadium purification.

[0075] (2) The pH value of the acid leaching solution was adjusted to 0.65 with KOH, and a mixed solvent of 40% N263 + 20% TBP + 40% sulfonated kerosene was used as the extractant. The phase ratio O / A = 1:2 was used for extraction for 1 min. The acid leaching solution was subjected to six-stage countercurrent extraction to obtain a mixed loaded organic phase with a vanadium concentration of 3.27 g / L. The extraction rates of vanadium, iron, aluminum and oxalate were 98.50%, 99.64%, 8.51% and 71.61% respectively. The vanadium-aluminum separation coefficient reached 757.54, and selective extraction separation of vanadium and aluminum was achieved. The vanadium-iron separation coefficient was only 0.25.

[0076] (3) The mixed-loaded organic phase was washed twice with 0.1 mol / L HCl. Using 8 mol / L HCl as the stripping agent, under the conditions of an organic-to-aqueous phase ratio O / A = 4:1 and a stripping time of 3 min, a vanadium-rich solution with V 12.51 g / L, Fe 0.034 g / L, and Al 5.31 g / L was obtained through four-stage countercurrent stripping. The stripping rates of vanadium, iron, aluminum, and oxalate were 99.58%, 0.13%, 99.60%, and 98.82% respectively, and the iron-vanadium separation coefficient was as high as 2050.90, achieving the selective stripping separation of vanadium and iron.

[0077] (4) Using 1.5 mol / L NaOH as the stripping agent for the iron-loaded organic phase, under the conditions of an organic-to-aqueous phase ratio O / A = 11 and a stripping time of 5 min, a iron-rich solution with an iron stripping rate of 99.44% was obtained through three-stage countercurrent stripping. The stripped solution was spray pyrolyzed in air to obtain vanadium pentoxide products with a product purity of 99.91%.

Claims

1. A method for purifying vanadium pentoxide from stone coal with high environmental protection and low energy consumption, It is characterized in that comprising: (1) Mixing vanadium-bearing stone coal particles, herbaceous biological materials of multiple size specifications, decellulosed lignin, fermentation bacterial materials, and anaerobic photosynthetic ferrous oxidizing bacteria tightly, and naturally fermenting in a summer environment with sunlight exposure on the top of the pile. Among them, the vanadium-bearing stone coal particles are stone coal powders collected from ore-bearing layers rich in V2O5 and Fe2O3, crushed and ground to a fineness of less than 0.1 mm, and the particle size is greater than 120 mesh ≥ 80%; the herbaceous biological materials of multiple size specifications are composed of small-sized herbaceous biological materials obtained by crushing woody biological materials into a size specification of 1 - 10 mm in length, width, and thickness, and large-sized herbaceous biological materials obtained by cutting herbaceous biological materials into a size specification of 100 - 300 mm in length; the decellulosed lignin is prepared by subjecting powdered herbaceous biological materials to defibrination treatment with cellulase and hemicellulase. The powdered herbaceous biological materials are obtained by coarsely crushing woody biological materials and / or herbaceous biological materials to a particle size of 2 - 4 cm, and then finely crushing to a particle size of 0.4 - 0.7 cm; (2) Collecting the fermentation exudate and performing precipitation and filtration treatments, extracting the filtrate with an organic extractant, and then back-extracting with an inorganic extractant to obtain a purified solution. Spraying and pyrolyzing the purified solution in an oxidizing atmosphere to obtain vanadium pentoxide.

2. The method according to claim 1, wherein the step (1) includes: Mixing small-sized herbaceous biological materials and decellulosed lignin with fermentation bacterial materials, and performing a water balance treatment at a temperature of 45 - 60 °C to obtain a moisture content of 6 - 12%; Drying or sun-drying the large-sized herbaceous biological materials and only performing a spraying treatment, with the spraying amount being 0.5 - 3% of the mass of the biological materials, or not performing a spraying treatment; Mixing and stirring the fermented materials obtained after the water balance treatment with large-sized herbaceous biomass, stacking in multiple layers, and dispersing and arranging fermentation bacterial materials and anaerobic photosynthetic ferrous oxidizing bacteria on the surface of each layer. After stacking, ferment in a temperature environment of 30 - 40 °C in summer.

3. The method according to claim 2, wherein Pressing a transparent or semi-transparent heavy object on the top of the pile to press the paving material tightly, and standing still for 3 - 5 weeks.

4. The method according to claim 1, wherein the fermentation bacterial materials are mushroom residues or mushroom bacterial liquid obtained by mashing and diluting mushrooms; the anaerobic photosynthetic ferrous oxidizing bacteria are Rhodomicrobium vannielii.

5. The method according to claim 1, wherein the content of V2O5 in the vanadium-bearing stone coal particles ≥ 0.9%, and the content of Fe2O3 ≥ 3.9%.

6. The method according to claim 1, wherein the woody biological materials are from wood processing residues, horticultural leftovers, recycled boards, and / or natural wood, and the herbaceous biological materials are from wheat straw, rice straw, and / or thin bamboo.

7. The method according to claim 1, wherein relative to 100 parts by mass of powdered herbaceous biological materials, 3 - 5 parts by mass of cellulase and 2 - 4 parts by mass of hemicellulase are used for defibrination treatment.

8. The method according to claim 1, wherein the mass ratio of vanadium-bearing stone coal particles to all plant materials is (1 - 2):10; The mass ratio of the large-sized herbaceous biomass, small-sized herbaceous biomass, and delignified lignin is 1:(1-1.5):(2-2.5).

9. The method according to claim 1, wherein the mass ratio of the fermentation bacterial material to all the plant materials is (0.15-0.2):1000; the mass ratio of the anoxic photoferrous oxidizing bacteria to the vanadium-bearing stone coal particles is (0.2-0.3):

100.

10. The method according to claim 1, wherein (2) includes: standing the collected exudate for 10-30 min, removing the precipitate, diluting and stirring with deionized water with a volume ratio of 1:5, standing again for 30-50 min to remove the precipitate, and then removing the organic biomass through a semipermeable membrane to obtain a purified acid leaching solution; adjusting the pH value of the acid leaching solution to 0.65 with KOH, using a mixed solvent of 40% N263 + 20% TBP + 40% sulfonated kerosene as the extractant, performing extraction for 1 min with a phase ratio O / A = 1:2, and performing six-stage countercurrent extraction to obtain a mixed loaded organic phase; washing the mixed loaded organic phase twice with 0.1 mol / L HCI, using 8 moL / L HCI as the stripping agent, and performing four-stage countercurrent stripping under the conditions of a phase ratio O / A = 4:1 and a stripping time of 3 min to obtain a vanadium-rich solution; spray pyrolyzing the vanadium-rich solution in the air to obtain a vanadium pentoxide product.

Images